WorldWideScience

Sample records for fk comae-type coronae

  1. Main: 1FK7 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK7 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...RGQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK7.jpg ...

  2. Main: 1FK5 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK5 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...ALVLLAAATSEAAISCGQVASAIAPCISYARGQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK5.jpg ...

  3. Main: 1FK6 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK6 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...RGQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK6.jpg ...

  4. Main: 1FK4 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK4 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...GQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK4.jpg ...

  5. Main: 1FK0 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK0 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...GQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK0.jpg ...

  6. Main: 1FK2 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK2 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...GQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK2.jpg ...

  7. Main: 1FK3 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK3 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...GQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK3.jpg ...

  8. Main: 1FK1 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1FK1 トウモロコシ Corn Zea mays L. Nonspecific Lipid-Transfer Protein Precursor Zea Mays ...RGQGSGPSAGCCSGVRSLNNAARTTADRRAACNCLKNAAAGVSGLNAGNAASIPSKCGVSIPYTISTSTDCSRVN corn_1FK1.jpg ...

  9. FK/Fpi from BMW

    CERN Document Server

    Ramos, A; Fodor, Z; Hoelbling, C; Katz, S D; Krieg, S; Kurth, T; Lellouch, L; Lippert, T; Szabo, K K

    2011-01-01

    Based on a series of lattice calculations we determine the ratio FK/Fpi in QCD. With experimental data from kaon decay and nuclear double beta decay, we obtain a precise determination of |Vus|. Our simulation includes 2+1 flavours of sea quarks, with three lattice spacings, large volumes and a simulated pion mass reaching down to about 190 MeV for a full control over the systematic uncertainties.

  10. On the rarity of FK Com stars

    Science.gov (United States)

    Hagen, W.; Stencel, R. E.

    1985-01-01

    Very high-dispersion spectra (2.5 A/mm) were obtained of 31 southern late-type stars, predominantly early G giants, in an effort to find new rapidly rotating, active stars which would be FK Com-like. Measurements of linewidths and the strength of chromospheric Ca II K-line emission are presented, but no new star could be added to the class of 'rapid rotators'. Space densities and evolutionary lifetimes for FK Com stars are discussed.

  11. Corona Borealis

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    (the Northern Crown; abbrev. CrB, gen. Coronae Borealis; area 179 sq. deg.) A northern constellation which lies between Boötes and Hercules, and culminates at midnight in mid-May. It represents the crown that in Greek mythology was made by Hephaestus, god of fire, and worn by Princess Ariadne of Crete. Its brightest stars were cataloged by Ptolemy (c. AD 100-175) in the Almagest....

  12. FK228 from Burkholderia thailandensis MSMB43

    Directory of Open Access Journals (Sweden)

    Xiang-Yang Liu

    2012-09-01

    Full Text Available FK228 [systematic name: (1S,4S,7Z,10S,16E,21R-7-ethylidene-4,21-di(propan-2-yl-2-oxa-12,13-dithia-5,8,20,23-tetrazabicyclo[8.7.6]tricos-16-ene-3,6,9,19,22-pentone], C24H36N4O6S2, also known as FR901228, depsipeptide, NSC 630176, romidepsin, and marketed as Istodax by Celgene Corporation, is crystallized from ethyl acetate in P21 as compared to the absolute configuration of FK228, first crystallized from methanol in P212121 [Shigematsu et al. (1994. J. Antibiot. 47, 311–314]. A slight difference is observed between the absolute configuration of FK228 and the present structure. The molecular structure is stabilized by intramolecular N—H...O hydrogen bonds. In the crystal, molecules are linked via N—H...O hydrogen bonds.

  13. Immunomodulation effects of heat-treated Enterococcus faecalis FK-23(FK-23) in mice

    Institute of Scientific and Technical Information of China (English)

    Takashi Shimada; Yunqing Cai; Lei Cheng; Chie Motonaga; Kazutake Fukada; Yoshihisa Kitamura; Jieshu Wu

    2009-01-01

    Objective:The purpose of this study was to evaluate the effects of Enterococcus faecalis FK-23(FK-23) on the immune function in mice. Methods:Mice were treated with three doses of the FK-23(0.05, 0.1, 0.2, 0.6 g/kg body weight) for 30 days. Delayed type hypersensitivity (DTH), monocyte phagocytic function, serum hemolysis antibody and natural killer cell activity were studied. Results: The significant increases in mice treated with 0.6 g/kg bw were found in DTH, phagocytic function of monocyte, serum hemolysis antibody and natural killer cell activity. Conclusion:The results from the present study suggest that FK-23 could improve both specific and nonspecific immune function.

  14. The FK Comae candidate UX Librae

    Science.gov (United States)

    Bopp, B. W.; Goodrich, B. D.; Africano, J. L.; Noah, P. V.; Meredith, R. J.; Palmer, L. H.; Quigley, R. J.

    1984-01-01

    New optical spectroscopic and photometric data are presented for the active chromosphere FK Com candidate UZ Lib. The star is shown to have an extremely large photometric amplitude in V of 0.35 mag, and its rotation period is established as 4.75 + or - 0.01 days. The optical spectrum is that of an early K giant, broadened by a rotation velocity of approximately 65 km/s. H-alpha is visible as a very broad emission feature, with a profile resembling that seen in FK Com. The emission intensity and profile are variable over the rotation period, with the strongest emission present at photometric minimum, in accord with dark starspot models. The photospheric absorption line profiles show variable asymmetries and distortions which are interpreted as due to the effects of the dark starspot rotating across the line of sight. New radial velocity measures are combined with published data to demonstrate the UZ Lib is a member of a binary system in synchronous rotation with a secondary of mass approximately 0.5 solar masses. This information is considered in light of the conflicting models for the origin of the optical and spectral variability of the FK Com stars, as well as their uncertain evolutionary status.

  15. FK228 from Burkholderia thailandensis MSMB43.

    Science.gov (United States)

    Liu, Xiang-Yang; Wang, Cheng; Cheng, Yi-Qiang

    2012-09-01

    FK228 [systematic name: (1S,4S,7Z,10S,16E,21R)-7-ethyl-idene-4,21-di(propan-2-yl)-2-oxa-12,13-dithia-5,8,20,23-tetra-za--bicyclo[8.7.6]tricos-16-ene-3,6,9,19,22-pentone], C(24)H(36)N(4)O(6)S(2), also known as FR901228, depsipeptide, NSC 630176, romidepsin, and marketed as Istodax by Celgene Corporation, is crystallized from ethyl acetate in P2(1) as compared to the absolute configuration of FK228, first crystallized from methanol in P2(1)2(1)2(1) [Shigematsu et al. (1994 ▶). J. Anti-biot.47, 311-314]. A slight difference is observed between the absolute configuration of FK228 and the present structure. The molecular structure is stabilized by intramolecular N-H⋯O hydrogen bonds. In the crystal, molecules are linked via N-H⋯O hydrogen bonds.

  16. Ultrasonic corona sensor study

    Science.gov (United States)

    Harrold, R. T.

    1976-01-01

    The overall objective of this program is to determine the feasibility of using ultrasonic (above 20 kHz) corona detection techniques to detect low order (non-arcing) coronas in varying degrees of vacuum within large high vacuum test chambers, and to design, fabricate, and deliver a prototype ultrasonic corona sensor.

  17. Improvement of FK506 production by synthetic biology approaches.

    Science.gov (United States)

    Fu, Li-Feng; Tao, Yang; Jin, Mei-Ying; Jiang, Hui

    2016-12-01

    Synthetic biology has been applied to direct improvement of valuable metabolite productions. Tacrolimus (FK506), a clinically used immunosuppressive agent isolated from many Streptomyces, is produced by fermentation in industry. Here we chose FK506 as an example to review recent progress in improving FK506 production, including enhancing transcription levels of biosynthetic genes, accelerating post-translational modification levels of biosynthetic enzymes, increasing activities of rate limiting enzymes, and rational supplement of limited precursors. FK506 production was increased from 25 % to sevenfold by these synthetic biology approaches.

  18. FK Comae Berenices, King of Spin

    DEFF Research Database (Denmark)

    Ayres, Thomas R.; Kashyap, V.; Saar, S.

    2016-01-01

    -ray emissions, and proclivity to flare. COCOA-PUFS was carried out with the Hubble Space Telescope in the UV (1200-3000 Å), using mainly its high-performance Cosmic Origins Spectrograph, but also high precision Space Telescope Imaging Spectrograph; Chandra X-ray Observatory in the soft X-rays (0.5-10 ke......V), utilizing its High-Energy Transmission Grating Spectrometer; together with supporting photometry and spectropolarimetry in the visible from the ground. This is an introductory report on the project. FK Com displayed variability on a wide range of timescales over all wavelengths during the week-long main...

  19. Crystal structure of the FK506 binding domain of human FKBP25 in complex with FK506.

    Science.gov (United States)

    Prakash, Ajit; Rajan, Sreekanth; Yoon, Ho Sup

    2016-04-01

    Human FKBP25 (hFKBP25) is a nuclear immunophilin and interacts with several nuclear proteins, hence involving in many nuclear events. Similar to other FKBPs, FK506 binding domain (FKBD) of hFKBP25 also binds to immunosuppressive drugs such as rapamycin and FK506, albeit with a lower affinity for the latter. The molecular basis underlying this difference in affinity could not be addressed due to the lack of the crystal structure of hFKBD25 in complex with FK506. Here, we report the crystal structure of hFKBD25 in complex with FK506 determined at 1.8 Å resolution and its comparison with the hFKBD25-rapamycin complex, bringing out the microheterogeneity in the mode of interaction of these drugs, which could possibly explain the lower affinity for FK506.

  20. Corona helps curb losses

    Energy Technology Data Exchange (ETDEWEB)

    Laasonen, M.; Lahtinen, M.; Lustre, L.

    1996-11-01

    The greatest power losses in electricity transmission arise through a phenomenon called load losses. Corona losses caused by the surface discharge of electricity also constitute a considerable cost item. IVS, the nationwide network company, is investigating corona- induced losses, and has also commissioned similar research from IVO International, the Technical Research Centre of Finland (VTT) and from Tampere University of Technology. The research work strives to gain more in-depth knowledge on the phenomenon of frosting and its impact on corona losses. The correct prediction of frost helps reduce corona losses, while also cutting costs considerably. (orig.)

  1. Corona helps curb losses

    Energy Technology Data Exchange (ETDEWEB)

    Laasonen, M.; Lahtinen, M.; Lustre, L.

    1996-11-01

    The greatest power losses in electricity transmission arise through a phenomenon called load losses. Corona losses caused by the surface discharge of electricity also constitute a considerable cost item. IVS, the nationwide network company, is investigating corona- induced losses, and has also commissioned similar research from IVO International, the Technical Research Centre of Finland (VTT) and from Tampere University of Technology. The research work strives to gain more in-depth knowledge on the phenomenon of frosting and its impact on corona losses. The correct prediction of frost helps reduce corona losses, while also cutting costs considerably. (orig.)

  2. Mixing up the Tropical Pacific (FK150728, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Cruise FK150728 of RV Falkor operated by Schmidt Ocean Institute, departing port Majuro, Marshall Islands on date 2015-07-28 and arriving port Honolulu, Hawaii on...

  3. Disease specific protein corona

    Science.gov (United States)

    Rahman, M.; Mahmoudi, M.

    2015-03-01

    It is now well accepted that upon their entrance into the biological environments, the surface of nanomaterials would be covered by various biomacromolecules (e.g., proteins and lipids). The absorption of these biomolecules, so called `protein corona', onto the surface of (nano)biomaterials confers them a new `biological identity'. Although the formation of protein coronas on the surface of nanoparticles has been widely investigated, there are few reports on the effect of various diseases on the biological identity of nanoparticles. As the type of diseases may tremendously changes the composition of the protein source (e.g., human plasma/serum), one can expect that amount and composition of associated proteins in the corona composition may be varied, in disease type manner. Here, we show that corona coated silica and polystyrene nanoparticles (after interaction with in the plasma of the healthy individuals) could induce unfolding of fibrinogen, which promotes release of the inflammatory cytokines. However, no considerable releases of inflammatory cytokines were observed for corona coated graphene sheets. In contrast, the obtained corona coated silica and polystyrene nanoparticles from the hypofibrinogenemia patients could not induce inflammatory cytokine release where graphene sheets do. Therefore, one can expect that disease-specific protein coronas can provide a novel approach for applying nanomedicine to personalized medicine, improving diagnosis and treatment of different diseases tailored to the specific conditions and circumstances.

  4. Corona SDK hotshot

    CERN Document Server

    Flanagan, Nevin

    2013-01-01

    Using a project based approach you will learn the coolest aspects of Corona SDK development. Each project contains step bystep explanations, diagrams, screenshots, and downloadable materials.This book is for users who already have completed at least one simple app using Corona and are familiar with mobile development using another platform and have done Lua programming in another context. Knowledge of the basic functions of Corona routines, as well as an understanding of the Lua programming language's syntax and common libraries, is assumed throughout.

  5. Rosat observations of FK comae berenices

    Science.gov (United States)

    Welty, Alan D.; Ramsey, Lawrence W.

    1994-01-01

    We obtained ROSAT PSPC observations of FK Com over a period of 24.4 h, or 0.42 rotation. During the observations the x-ray flux increased by a factor of at least 5 before declining toward its previous level. A single temperature Raymond-Smith model is adequate to model the low signal-to-noise ratio spectrum from each observation interval. Initially the spectrum was that of a 8.5 x 10(exp 6) K plasma, with L9sub x)=0.66 x 10(exp 31) erg s(exp -1). When the x-ray flux was greatest, the model plasma temperature rose to 2.5 x 10(exp 7) K, and L(sub x)=3.46 x 10(exp 31) ergs(exp -1). During the post-maximum decline in luminosity the plasma temperature was approximately 12 x 10(exp 6) K. We conclude that the increase of x-ray flux recorded by ROSAT was due to an x-ray flare with a 1.5 h decline time scale.

  6. Rosat observations of FK comae berenices

    Science.gov (United States)

    Welty, Alan D.; Ramsey, Lawrence W.

    1994-01-01

    We obtained ROSAT PSPC observations of FK Com over a period of 24.4 h, or 0.42 rotation. During the observations the x-ray flux increased by a factor of at least 5 before declining toward its previous level. A single temperature Raymond-Smith model is adequate to model the low signal-to-noise ratio spectrum from each observation interval. Initially the spectrum was that of a 8.5 x 10(exp 6) K plasma, with L9sub x)=0.66 x 10(exp 31) erg s(exp -1). When the x-ray flux was greatest, the model plasma temperature rose to 2.5 x 10(exp 7) K, and L(sub x)=3.46 x 10(exp 31) ergs(exp -1). During the post-maximum decline in luminosity the plasma temperature was approximately 12 x 10(exp 6) K. We conclude that the increase of x-ray flux recorded by ROSAT was due to an x-ray flare with a 1.5 h decline time scale.

  7. Stolt's f-k migration for plane wave ultrasound imaging.

    Science.gov (United States)

    Garcia, Damien; Le Tarnec, Louis; Muth, Stéphan; Montagnon, Emmanuel; Porée, Jonathan; Cloutier, Guy

    2013-09-01

    Ultrafast ultrasound is an emerging modality that offers new perspectives and opportunities in medical imaging. Plane wave imaging (PWI) allows one to attain very high frame rates by transmission of planar ultrasound wave-fronts. As a plane wave reaches a given scatterer, the latter becomes a secondary source emitting upward spherical waves and creating a diffraction hyperbola in the received RF signals. To produce an image of the scatterers, all the hyperbolas must be migrated back to their apexes. To perform beamforming of plane wave echo RFs and return high-quality images at high frame rates, we propose a new migration method carried out in the frequency-wavenumber (f-k) domain. The f-k migration for PWI has been adapted from the Stolt migration for seismic imaging. This migration technique is based on the exploding reflector model (ERM), which consists in assuming that all the scatterers explode in concert and become acoustic sources. The classical ERM model, however, is not appropriate for PWI. We showed that the ERM can be made suitable for PWI by a spatial transformation of the hyperbolic traces present in the RF data. In vitro experiments were performed to outline the advantages of PWI with Stolt's f-k migration over the conventional delay-and-sum (DAS) approach. The Stolt's f-k migration was also compared with the Fourier-based method developed by J.-Y. Lu. Our findings show that multi-angle compounded f-k migrated images are of quality similar to those obtained with a stateof- the-art dynamic focusing mode. This remained true even with a very small number of steering angles, thus ensuring a highly competitive frame rate. In addition, the new FFT-based f-k migration provides comparable or better contrast-to-noise ratio and lateral resolution than the Lu's and DAS migration schemes. Matlab codes for the Stolt's f-k migration for PWI are provided.

  8. Experiment Study of Retinal Ultrastructure after Intravitreal FK506

    Institute of Scientific and Technical Information of China (English)

    Shuangnong Li; Shibo Tang; Wei Li; Dongping Li

    2004-01-01

    Purpose:To investigate the retinal toxicity of FK506 by intravitreal administration.Methods :Twenty-two eyes of 14 New Zealand rabbits were investigated. FK506 at con centrations of 5,25 and 50μg/eye was injected into the vitreous cavitiesrespectively.The control eyes were received mixed solution of balanced salt and ethanol. All eyes were examined by tonometry, slit lamp and indirect ophthalmoscopy preoperatively and post operatively at the 1st, 3rd, 7th, and 14th day respectively. In the final examination, all eyes were enucleated and processed for light and electron microscopy. Conclusion: It is safety with intravitreal FK506. There are no irritation and toxicity to the are proved to be toxic to the retina. Eye Science 2004;20:34-38.

  9. Cosine problem in EPRL/FK spinfoam model

    CERN Document Server

    Vojinovic, Marko

    2014-01-01

    We calculate the classical limit effective action of the EPRL/FK spinfoam model of quantum gravity coupled to matter fields. By employing the standard QFT background field method adapted to the spinfoam setting, we find that the model has many different classical effective actions. Most notably, these include the ordinary Einstein-Hilbert action coupled to matter, but also an action which describes antigravity. All those multiple classical limits appear as a consequence of of the fact that the EPRL/FK vertex amplitude has cosine-like large spin asymptotics. We discuss some possible ways to eliminate the unwanted classical limits.

  10. Cosine problem in EPRL/FK spinfoam model

    Science.gov (United States)

    Vojinović, Marko

    2014-01-01

    We calculate the classical limit effective action of the EPRL/FK spinfoam model of quantum gravity coupled to matter fields. By employing the standard QFT background field method adapted to the spinfoam setting, we find that the model has many different classical effective actions. Most notably, these include the ordinary Einstein-Hilbert action coupled to matter, but also an action which describes antigravity. All those multiple classical limits appear as a consequence of the fact that the EPRL/FK vertex amplitude has cosine-like large spin asymptotics. We discuss some possible ways to eliminate the unwanted classical limits.

  11. EST Table: FK250588 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FK250588 EEG176 10/09/28 79 %/125 aa ref|ZP_05092873.1| phage tail tape measure pro...tein, lambda family [Carboxydibrachium pacificum DSM 12653] gb|EEB75267.1| phage tail tape measure protein,

  12. Finiteness of the EPRL/FK spin foam model

    CERN Document Server

    Mikovic, Aleksandar

    2011-01-01

    We show that the EPRL/FK spin foam model of quantum gravity can be made finite by dividing the vertex amplitude with an appropriate power $p$ of the product of dimensions of the vertex spins and intertwiners. This power is independent of the spin foam and we find a lower bound for $p$ which makes the state sum absolutely convergent.

  13. Effective action for EPRL/FK spin foam models

    CERN Document Server

    Mikovic, Aleksandar

    2011-01-01

    We show that a natural modification of the EPRL/FK vertex amplitude gives a finite spin foam model whose effective action gives the Einstein-Hilbert action in the limit of large spins and arbitrarily fine spacetime triangulations. The first-order quantum corrections can be easily computed and we show how to calculate the higher-order corrections.

  14. Corona SDK application design

    CERN Document Server

    Williams, Daniel

    2013-01-01

    A step by step tutorial that focuses on everything from setup to deployment of basic apps.Have you ever wanted to create your own app? Then this book is for you. You will learn how to create apps using Corona SDK and how to publish your app so others can get a glimpse of your creation. This book is aimed at both Android and iOS app developers. The reader must have basic knowledge of app development.

  15. Corona and solar wind

    Science.gov (United States)

    Withbroe, G. L.

    1986-04-01

    The Pinhole/Occulter Facility is a powerful tool for studying the physics of the extended corona and origins of the solar wind. Spectroscopic data acquired by the P/OF coronal instruments can greatly expand empirical information about temperatures, densities, flow velocities, magnetic fields, and chemical abundances in the corona out to r or approx. 10 solar radii. Such information is needed to provide tight empirical constraints on critical physical processes involved in the transport and dissipation of energy and momentum, the heating and acceleration of plasma, and the acceleration of energetic particles. Because of its high sensitivity, high spatial and temporal resolutions, and powerful capabilities for plasma diagnostics, P/OF can significantly increase our empirical knowledge about coronal streamers and transients and thereby advance the understanding of the physics of these phenomena. P/OF observations can be used to establish the role in solar wind generation, if any, of small-scale dynamical phenomena, such as spicules, macrospicules and coronal bullets, and the role of the fine-scale structures, such as polar plumes. Finally, simultaneous measurements by the P/OF coronal and hard X-ray instruments can provide critical empirical information concerning nonthermal energy releases and acceleration of energetic particles in the corona.

  16. PET measurement of FK506 concentration in a monkey model of stroke

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Yoshihiro [Medical and Pharmacological Research Center Foundation, Hakui City, Ishikawa 925-0613 (Japan); Analysis and Pharmacokinetics Research Laboratories, Astellas Pharma Inc., Tsukuba, Ibaraki 305-8585 (Japan)], E-mail: murakami@mprcf.or.jp; Takamatsu, Hiroyuki [Medical and Pharmacological Research Center Foundation, Hakui City, Ishikawa 925-0613 (Japan); Noda, Akihiro [Medical and Pharmacological Research Center Foundation, Hakui City, Ishikawa 925-0613 (Japan); Analysis and Pharmacokinetics Research Laboratories, Astellas Pharma Inc., Tsukuba, Ibaraki 305-8585 (Japan); Osoda, Kazuhiko [Chemical Research Laboratories, Astellas Pharma Inc., Tsukuba, Ibaraki 305-8585 (Japan); Nishimura, Shintaro [Medical and Pharmacological Research Center Foundation, Hakui City, Ishikawa 925-0613 (Japan); Analysis and Pharmacokinetics Research Laboratories, Astellas Pharma Inc., Tsukuba, Ibaraki 305-8585 (Japan)

    2007-08-15

    Introduction: The immunosuppressive agent FK506 (tacrolimus) has neuroprotective properties in an experimental model of cerebral ischemia. To improve the accuracy of clinical studies in acute stroke, a clinical dose setting should be based on the brain concentration, but not on the blood concentration of agents in humans. We have already established a measurement method using PET for FK506 concentration in the normal monkey brain, which could be applicable for human study; however, under ischemic conditions, in this study, we aimed to examine the brain concentration of FK506 in a monkey model of stroke. Methods: Studies were performed on six male cynomolgus monkeys (Macaca fascicularis) and a middle cerebral artery (MCA) occlusion model was used. Regional cerebral blood flow (rCBF) was measured by an intravenous injection of [{sup 15}O]H{sub 2}O 165 min after MCA occlusion. FK506 (0.1 mg/kg) containing [{sup 11}C]FK506 was intravenously injected into the monkeys 180 min after MCA occlusion, and dynamic PET images were acquired for 30 min after administration. FK506 concentrations in the brain were calculated in moles per liter (M) units using the specific activity of injected FK506. Results: MCA occlusion produced ischemia, confirmed by rCBF measurement before the administration of [{sup 11}C]FK506. Fifteen minutes after FK506 (0.1 mg/kg) administration, the concentrations in the contralateral and ipsilateral cortex were 22.4{+-}6.4 and 19.7{+-}4.0 ng/g, respectively. Conclusion: We successfully measured the brain concentration of FK506 in a monkey model of stroke. The difference between the contralateral and ipsilateral concentrations of FK506 was not significant. This characteristic that FK506 readily penetrates ischemic tissue as well as normal tissue might explain the neuroprotective effect of FK506 in the ischemic brain and is suitable for the treatment of stroke patients.

  17. Pengaruh Penggunaan Kafein Terhadap Kualitas Tidur Mahasiswa Fk Usu

    OpenAIRE

    Saliimah, Maryam Balqis

    2016-01-01

    Caffeine is a xanthine derivative alkaloid compound (purine bases) in the form of white crystals. Caffeine is a chemical compund that is found naturally in foods example coffee beans, tea, oil seeds, and mate. Caffeine is a psychoactive, used as a central nervous system stimulant, accelerates metabolism and diuretic. The purpose of this study was to determine the effect of caffeine on sleep quality of FK USU students. This study is a clinical trial that is cross-sectional. S...

  18. Test characteristics of two rapid antigen detection tests (SD FK50 and SD FK60 for the diagnosis of malaria in returned travellers

    Directory of Open Access Journals (Sweden)

    Van Esbroeck Marjan

    2009-05-01

    Full Text Available Abstract Background Two malaria rapid diagnostic tests were evaluated in a travel clinic setting: the SD FK50 Malaria Ag Plasmodium falciparum test (a two-band test and the SD FK60 Malaria Ag P. falciparum/Pan test (a three-band test. Methods A panel of stored whole blood samples (n = 452 and n = 614 for FK50 and FK60, respectively from returned travellers was used. The reference method was microscopy with PCR in case of discordant results. Results For both tests, overall sensitivity for the detection of P. falciparum was 93.5%, reaching 97.6% and 100% at parasite densities above 100 and 1,000/μl respectively. Overall sensitivities for Plasmodium vivax, Plasmodium ovale and Plasmodium malariae for the FK60 test were 87.5%, 76.3% and 45.2%, but they reached 92.6% and 90.5% for P. vivax and P. ovale at parasite densities above 500/μl. Specificities were above 95% for all species and both tests when corrected by PCR, with visible histidine-rich protein-2 lines for P. malariae (n = 3 and P. vivax and P. ovale (1 sample each. Line intensities were reproducible and correlated to parasite densities. The FK60 tests provided clues to estimate parasite densities for P. falciparum below or above 1,000/μl. Conclusion Both the FK50 and FK60 performed well for the diagnosis of P. falciparum in the present setting, and the FK60 for the diagnosis of P. vivax and P. ovale at parasite densities > 500/μl. The potential use of the FK60 as a semi-quantitative estimation of parasite density needs to be further explored.

  19. Acute Cerebral Infarction after FK 506 Administration in a Kidney Transplantation Recipient: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Ji Kyung; Byun, Woo Mok; Kim, Jae Woon [Yeungnam University College of Medicine, Daegu (Korea, Republic of)

    2011-02-15

    FK506 is widely used as a potent immunosuppressive agent following organ transplantation. However, the use of FK506 is associated with a wide spectrum of neurotoxicity. FK506-induced cerebral infarctions have rarely been reported. We report here on a case of the acute cerebral infarction caused by vasospasm after FK506 administration in a kidney transplantation recipient. There were areas with increased signal intensity on the diffusion-weighted image. The areas showing increased signal intensity on the diffusion- and T2-weighted images demonstrated decreased signal intensity on the apparent diffusion coefficient mapping. MR angiography showed diffuse stenosis in both the anterior and middle cerebral arteries

  20. A note on magnetized coronae

    CERN Document Server

    Belmont, R

    2008-01-01

    X-ray binaries and AGN show observational evidence for magnetized hot plasmas. Despite years of data, very little is known on these {\\it coronae} especially on the mechanisms responsible for their heating, and most models simply assume their existence. However, understanding its properties has now become a key issue of the AGN and microquasars modelling. Here we consider the effect of a strong vertical magnetic field on the corona AGN and X-ray binaries and show that its modeling (structure, heating) must be reconsidered. As a first step, we present one mechanism that could extract energy from the accretion disks and deposits it in the coronae: the {\\it magnetic pumping

  1. Snowfall induced by corona discharge

    CERN Document Server

    Ju, Jingjing; Li, Ruxin; Du, Shengzhe; Sun, Haiyi; Liu, Yonghong; Tian, Ye; Bai, Yafeng; Liu, Yaoxiang; Chen, Na; Wang, Jingwei; Wang, Cheng; Liu, Jiansheng; Chin, S L; Xu, Zhizhan

    2016-01-01

    We demonstrated for the first time the condensation and precipitation (or snowfall) induced by a corona discharge inside a cloud chamber. Ionic wind was found to have played a more significant role than ions as extra Cloud Condensation Nuclei (CCN). 2.25 g of net snow enhancement was measured after applying a 30 kV corona discharge for 25 min. In comparison with another newly emerging femtosecond laser filamentation method, the snow precipitation induced by the corona discharge has about 4 orders of magnitude higher wall-plug efficiency under similar conditions.

  2. Flare Heating in Stellar Coronae

    CERN Document Server

    Kashyap, V L; Güdel, M; Audard, M; Kashyap, Vinay; Drake, Jeremy; Guedel, Manuel; Audard, Marc

    2002-01-01

    We investigate the contribution of very weak flares to the coronal luminosity of low-mass active stars. We analyze EUVE/DS events data from FK Aqr, V1054 Oph, and AD Leo and conclude that in all these cases the coronal emission is dominated by flares to such an extent that in some cases the entire emission may be ascribed to flare heating. We have developed a new method to directly model for the first time stochastically produced flare emission, including undetectable flares, and their effects on the observed photon arrival times. We find that the index of the power-law distribution of flare energies (dN/dE ~ E^{-alpha}) is 2.6+-0.34, 2.74+-0.35, and 2.03-2.32 for FK Aqr, V1054 Oph, and AD Leo respectively. We also find that the flare component accounts for a large fraction (generally >50 percent) of the total flux.

  3. InterProScan Result: FK250565 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FK250565 FK250565_5_ORF1 5AB37CFF9C7463AA PROSITE PS01079 MOCF_BIOSYNTHESIS_2 NA T ...IPR008284 Molybdenum cofactor biosynthesis, conserved site Biological Process: Mo-molybdopterin cofactor biosynthetic process (GO:0006777) ...

  4. Use of FK506 and bone marrow mesenchymal stem cells for rat hind limb allografts

    Institute of Scientific and Technical Information of China (English)

    Youxin Song; Zhujun Wang; Zhixue Wang; Hong Zhang; Xiaohui Li; Bin Chen

    2012-01-01

    Dark Agouti rat donor hind limbs were orthotopically transplanted into Lewis rat recipients to verify the effects of bone marrow mesenchymal stem cells on neural regeneration and functional recovery of allotransplanted limbs in the microenvironment of immunotolerance. bone marrow mesenchymal stem cells were intramuscularly (gluteus maximus) injected with FK506 (tacrolimus) daily, and were transplanted to the injured nerves. Results indicated that the allograft group not receiving therapy showed severe rejection, with transplanted limbs detaching at 10 days after transplantation with complete necrosis. The number of myelinated axons and Schwann cells in the FK506 and FK506 + bone marrow mesenchymal stem cells groups were significantly increased. We observed a lesser degree of gastrocnemius muscle degeneration, and increased polymorphic fibers along with other pathological changes in the FK506 + bone marrow mesenchymal stem cells group. The FK506 + bone marrow mesenchymal stem cells group showed significantly better recovery than the autograft and FK506 groups. The results demonstrated that FK506 improved the immune microenvironment. FK506 combined with bone marrow mesenchymal stem cells significantly promoted sciatic nerve regeneration, and improved sensory recovery and motor function in hind limb allotransplant.

  5. FK506 regulates pigmentation by maturing the melanosome and facilitating their transfer to keratinocytes.

    Science.gov (United States)

    Jung, Hyejung; Chung, Heesung; Chang, Sung Eun; Kang, Duk-Hee; Oh, Eok-Soo

    2016-03-01

    Despite the clinical ability of topical tacrolimus (FK506) to effectively promote repigmentation in vitiligo, the underlying mechanism through which FK506 regulates melanogenesis was previously unclear. We found that FK506 treatment increased the melanin contents (especially that of eumelanin) in both melanocytes and melanoma cells. This treatment did not affect the transcription levels of tyrosinase, suggesting that FK506 increases melanin synthesis by regulating cellular levels of tyrosinase. Interestingly, FK506 promoted melanosome maturation by increasing melanosomal pH (a marker of melanosome maturation), thereby enhancing the stability of melanosome-localized tyrosinase. In addition, FK506 enhanced UVB-mediated melanosome secretion, the uptake of melanosomes by HaCaT cells, and the transfer of melanosomes to keratinocytes co-cultured with melanocytes. Together, these findings suggest that FK506 contributes to melanin synthesis by regulating the maturation of melanosomes and their transfer to keratinocytes. This offers a novel regulatory mechanism through which FK506 and UVB can have a combined effect on melanogenesis.

  6. Mode of action of FK-506 on protective immunity to Hymenolepis nana in mice.

    Science.gov (United States)

    Asano, K; Taki, M; Matsuo, S; Yamada, K

    1996-01-01

    FK-506 (Tacrolimus) has been shown to block T cell proliferation in vitro by inhibiting the generation of several lymphokines, especially interleukin (IL)-2, but little direct evidence is available to support the view that the immunosuppressive effects of FK-506 in vivo are mediated by a similar inhibition of lymphokine cascade. To investigate the mechanisms of FK-506-induced immunosuppression, the effects of FK-506 on cell-mediated immunity to Hymenolepis nana were examined in mice. FK-506 administration into BALB/c mice daily at a dose of 10.0 mg/kg (but not 5.0 mg/kg) for 5 days caused suppression of protective immunity against H. nana challenge infection. During the infection of mice with H. nana, IL-2 and interferon (IFN)-gama were produced by mesenteric lymph node (MLN) cells with a time course corresponding to that of MLN T cell proliferation. These responses were completely suppressed by repeated administration of FK-506 for 5 days at a dose of 10.0 mg/kg/day (but not 5.0 mg/kg/day). In contrast to the effects of FK-506 on IL-2 and IFN-gamma productions in MLN, IL-1 and tumor necrosis factor-alpha in the intestinal wall, which were enhanced by H. nana infection, were not completely decreased as a result of 10.0 mg/kg FK-506 treatment. The reverse transcriptase-PCR revealed complete inhibition of IL-2 and IFN-gamma mRNA expression on mesenteric L3T4+ cells that were induced by H. nana infection, when mice were given 10.0 mg/kg/day FK-506 for 5 days. These results strongly suggest that FK-506 affects cell-mediated immunity in vivo with mechanisms similar to those observed in vitro.

  7. FK506 biosynthesis is regulated by two positive regulatory elements in Streptomyces tsukubaensis

    Directory of Open Access Journals (Sweden)

    Goranovič Dušan

    2012-10-01

    Full Text Available Abstract Background FK506 (Tacrolimus is an important immunosuppressant, produced by industrial biosynthetic processes using various Streptomyces species. Considering the complex structure of FK506, it is reasonable to expect complex regulatory networks controlling its biosynthesis. Regulatory elements, present in gene clusters can have a profound influence on the final yield of target product and can play an important role in development of industrial bioprocesses. Results Three putative regulatory elements, namely fkbR, belonging to the LysR-type family, fkbN, a large ATP-binding regulator of the LuxR family (LAL-type and allN, a homologue of AsnC family regulatory proteins, were identified in the FK506 gene cluster from Streptomyces tsukubaensis NRRL 18488, a progenitor of industrial strains used for production of FK506. Inactivation of fkbN caused a complete disruption of FK506 biosynthesis, while inactivation of fkbR resulted in about 80% reduction of FK506 yield. No functional role in the regulation of the FK506 gene cluster has been observed for the allN gene. Using RT-PCR and a reporter system based on a chalcone synthase rppA, we demonstrated, that in the wild type as well as in fkbN- and fkbR-inactivated strains, fkbR is transcribed in all stages of cultivation, even before the onset of FK506 production, whereas fkbN expression is initiated approximately with the initiation of FK506 production. Surprisingly, inactivation of fkbN (or fkbR does not abolish the transcription of the genes in the FK506 gene cluster in general, but may reduce expression of some of the tested biosynthetic genes. Finally, introduction of a second copy of the fkbR or fkbN genes under the control of the strong ermE* promoter into the wild type strain resulted in 30% and 55% of yield improvement, respectively. Conclusions Our results clearly demonstrate the positive regulatory role of fkbR and fkbN genes in FK506 biosynthesis in S. tsukubaensis NRRL 18488. We

  8. Inhibition by FK506 of formyl peptide-induced neutrophil activation and associated protein synthesis.

    Science.gov (United States)

    Burnett, D; Adams, D H; Martin, T J; Liu, Q; Grant, R A; Stockley, R A; Lord, J M

    1994-09-15

    The macrolide FK506 inhibited, by up to 50%, neutrophil migration and the production of the superoxide radical in response to the formyl peptide, formyl-methionyl-leucyl-phenylalanine (FMLP). The production of the superoxide radical in response to phorbol 12-myristate 13-acetate (PMA) was unaffected by FK506. The inhibition of neutrophil functions was accompanied by a partial reversal of FMLP-induced synthesis of cellular proteins, despite a rise in intracellular Ca2+. Neutrophils treated with FK506 demonstrated a small (average 23%) though significant decrease in formyl-peptide receptor numbers but receptor binding affinity was unaffected. The effects of FK506 on neutrophil activation appear to be analogous to those in T-lymphocytes. The incomplete inhibition, by FK506, of neutrophil responses suggests further that activation by FMLP is mediated via distinct multiple signalling pathways, including protein kinase activation and protein synthesis. The inability of FK506 to reduce FMLP-induced rises in cellular Ca2+ or PMA-induced activation of neutrophils suggests that its action is distal to Ca2+ mobilization and distinct from pathways relying on PKC activation. Thus the immunosuppressive effects of FK506 in vivo might be mediated through the inhibition of inflammatory cells other than lymphocytes and the drug therefore has therapeutic potential in a variety of inflammatory conditions. The drug also has potential in vitro for the characterization of signalling pathways from the plasma membrane to the nucleus.

  9. FK506 activates BMPR2, rescues endothelial dysfunction, and reverses pulmonary hypertension

    Science.gov (United States)

    Spiekerkoetter, Edda; Tian, Xuefei; Cai, Jie; Hopper, Rachel K.; Sudheendra, Deepti; Li, Caiyun G.; El-Bizri, Nesrine; Sawada, Hirofumi; Haghighat, Roxanna; Chan, Roshelle; Haghighat, Leila; de Jesus Perez, Vinicio; Wang, Lingli; Reddy, Sushma; Zhao, Mingming; Bernstein, Daniel; Solow-Cordero, David E.; Beachy, Philip A.; Wandless, Thomas J.; ten Dijke, Peter; Rabinovitch, Marlene

    2013-01-01

    Dysfunctional bone morphogenetic protein receptor-2 (BMPR2) signaling is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). We used a transcriptional high-throughput luciferase reporter assay to screen 3,756 FDA-approved drugs and bioactive compounds for induction of BMPR2 signaling. The best response was achieved with FK506 (tacrolimus), via a dual mechanism of action as a calcineurin inhibitor that also binds FK-binding protein-12 (FKBP12), a repressor of BMP signaling. FK506 released FKBP12 from type I receptors activin receptor-like kinase 1 (ALK1), ALK2, and ALK3 and activated downstream SMAD1/5 and MAPK signaling and ID1 gene regulation in a manner superior to the calcineurin inhibitor cyclosporine and the FKBP12 ligand rapamycin. In pulmonary artery endothelial cells (ECs) from patients with idiopathic PAH, low-dose FK506 reversed dysfunctional BMPR2 signaling. In mice with conditional Bmpr2 deletion in ECs, low-dose FK506 prevented exaggerated chronic hypoxic PAH associated with induction of EC targets of BMP signaling, such as apelin. Low-dose FK506 also reversed severe PAH in rats with medial hypertrophy following monocrotaline and in rats with neointima formation following VEGF receptor blockade and chronic hypoxia. Our studies indicate that low-dose FK506 could be useful in the treatment of PAH. PMID:23867624

  10. Cool covered sky-splitting spectrum-splitting FK

    Energy Technology Data Exchange (ETDEWEB)

    Mohedano, Rubén; Chaves, Julio; Falicoff, Waqidi; Hernandez, Maikel; Sorgato, Simone [LPI, Altadena, CA, USA and Madrid (Spain); Miñano, Juan C.; Benitez, Pablo [LPI, Altadena, CA, USA and Madrid, Spain and Universidad Politécnica de Madrid (UPM), Madrid (Spain); Buljan, Marina [Universidad Politécnica de Madrid (UPM), Madrid (Spain)

    2014-09-26

    Placing a plane mirror between the primary lens and the receiver in a Fresnel Köhler (FK) concentrator gives birth to a quite different CPV system where all the high-tech components sit on a common plane, that of the primary lens panels. The idea enables not only a thinner device (a half of the original) but also a low cost 1-step manufacturing process for the optics, automatic alignment of primary and secondary lenses, and cell/wiring protection. The concept is also compatible with two different techniques to increase the module efficiency: spectrum splitting between a 3J and a BPC Silicon cell for better usage of Direct Normal Irradiance DNI, and sky splitting to harvest the energy of the diffuse radiation and higher energy production throughout the year. Simple calculations forecast the module would convert 45% of the DNI into electricity.

  11. The H Corona of Mars

    Science.gov (United States)

    Chaffin, Michael Scott

    The atmosphere of every planet is surrounded by a tenuous cloud of hydrogen gas, referred to as a hydrogen corona. At Mars, a substantial fraction of the H present in the corona is moving fast enough to escape the planet's gravity, permanently removing H from the Martian atmosphere. Because this H is ultimately derived from lower atmospheric water, loss of H from Mars is capable of drying and oxidizing the planet over geologic time. Understanding the processes that supply the H corona and control its escape is therefore essential for a complete understanding of the climate history of Mars and for assessing its habitability. In this thesis, I present the most complete analysis of the H corona ever attempted, surveying eight years of data gathered by the ultraviolet spectrograph SPICAM on Mars Express. Using a coupled radiative transfer and physical density model, I interpret brightness measurements of the corona in terms of escape rates of H from the planet, uncovering an order-of-magnitude variability in the H escape rate never before detected. These variations are interpreted using a completely new photochemical model of the atmosphere, demonstrating that newly discovered high altitude water vapor layers are sufficient to produce the observed variation. Finally, I present first results of the SPICAM successor instrument IUVS, an imaging ultraviolet spectrograph carried by NASA's MAVEN spacecraft. IUVS measurements are producing the most complete dataset ever gathered for the Martian H corona, enabling supply and loss processes to be assessed in more complete detail than ever before. This dataset will allow present-day loss rates to be extrapolated into the past, determining the absolute amount of water Mars has lost to space over the course of its history. Planets the size of Mars may be common throughout the universe; the work of this thesis is one step toward assessing the habitability of such planets in general.

  12. [The initial trial of the clinical use of FK-1 glue in surgical interventions].

    Science.gov (United States)

    Abzhueva, O V; Rusanov, V M; Zhidkov, I L

    2000-01-01

    The article presents results of a comparative clinical trial of the preparation "fibrinous glue" (FK-1) and "Beriplast" in operations on the lungs for hermetization of the wound and the lung as well as in reconstructive plastic gynecological operations. Intraoperative hermetization in operations on the lungs was obtained in 67% of the cases when using "FK-1" and in 64% with "Beriplast". In all the cases the lung was spread during 12 hours after operation. The visual intraoperative assessment of using "FK-1" and control laparoscopy on the 4th-5th days after operation showed its good effect in gynecological procedures. Clinical trials of the new domestic fibrinous glue "FK-1" in surgical and gynecological clinics confirmed its high medical effectiveness.

  13. Polychromatic Arm Exponents for the Critical Planar FK-Ising model

    OpenAIRE

    Wu, Hao

    2016-01-01

    We derive the arm exponents of SLE$_{\\kappa}$ for $\\kappa\\in (4,8)$ and explain how to combine them with the convergence of the interface to obtain the arm exponents of critical FK-Ising model. We obtain six different patterns of boundary arm exponents and three different patterns of interior arm exponents of the critical planar FK-Ising model on the square lattice.

  14. Molecular mechanisms of FK506-induced hypertension in solid organ transplantation patients

    Institute of Scientific and Technical Information of China (English)

    Wang Jianglin; Guo Ren; Liu Shikun; Chen Qingjie; Zuo Shanru; Yang Meng; Zuo Xiaocong

    2014-01-01

    Objective Tacrolimus (FK506) is an immunosuppressive drug,which is widely used to prevent rejection of transplanted organs.However,chronic administration of FK506 leads to hypertension in solid organ transplantation patients,and its molecular mechanisms are much more complicated.In this review,we will discuss the above-mentioned molecular mechanisms of FK506-induced hypertension in solid organ transplantation subjects.Data sources The data analyzed in this review were mainly from relevant articles without restriction on the publication date reported in PubMed.The terms "FK506" or "tacrolimus" and "hypertension"were used for the literature search.Study selection Original articles with no limitation of research design and critical reviews containing data relevant to FK506-induced hypertension and its molecular mechanisms were retrieved,reviewed and analyzed.Results There are several molecular mechanisms attributed to FK506-induced hypertension in solid organ transplantation subjects.First,FK506 binds FK506 binding protein 12 and its related isoform 12.6 (FKBP12/12.6) and removes them from intracellular ryanodine receptors that induce a calcium ion leakage from the endoplasmic/sarcoplasmic reticulum.The conventional protein kinase C beta II (cPKCβⅡ)-mediated phosphorylation of endothelial nitric oxide (NO) synthase at Thr495,which reduces the production of NO,was activated by calcium ion leakage.Second,transforming growth factor receptor/SMAD2/3 signaling activation plays an important role in Treg/Th17 cell imbalance in T cells which toget converge to cause inflammation,endothelial dysfunction,and hypertension following tacrolimus treatment.Third,the activation of with-no-K(Lys) kinases/STE20/SPS1-related proline/alanine-rich kinase/thiazide-sensitive sodium chloride co-transporter (WNKs/SPAK/NCC) pathway has a central role in tacrolimus-induced hypertension.Finally,the enhanced activity of renal renin-angiotensin-aldosterone system seems to play a crucial role in

  15. FK866-induced NAMPT inhibition activates AMPK and downregulates mTOR signaling in hepatocarcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Susanne, E-mail: Susanne.Schuster@medizin.uni-leipzig.de [Center for Pediatric Research Leipzig, University Hospital for Children and Adolescents, Faculty of Medicine, University of Leipzig, Liebigstr. 21, 04103 Leipzig (Germany); Penke, Melanie; Gorski, Theresa [Center for Pediatric Research Leipzig, University Hospital for Children and Adolescents, Faculty of Medicine, University of Leipzig, Liebigstr. 21, 04103 Leipzig (Germany); Gebhardt, Rolf [Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Johannisallee 30, 04103 Leipzig (Germany); Weiss, Thomas S. [Children' s University Hospital, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg (Germany); Kiess, Wieland; Garten, Antje [Center for Pediatric Research Leipzig, University Hospital for Children and Adolescents, Faculty of Medicine, University of Leipzig, Liebigstr. 21, 04103 Leipzig (Germany)

    2015-03-06

    Background: Nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme of the NAD salvage pathway starting from nicotinamide. Cancer cells have an increased demand for NAD due to their high proliferation and DNA repair rate. Consequently, NAMPT is considered as a putative target for anti-cancer therapies. There is evidence that AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) become dysregulated during the development of hepatocellular carcinoma (HCC). Here, we investigated the effects of NAMPT inhibition by its specific inhibitor FK866 on the viability of hepatocarcinoma cells and analyzed the effects of FK866 on the nutrient sensor AMPK and mTOR complex1 (mTORC1) signaling. Results: FK866 markedly decreased NAMPT activity and NAD content in hepatocarcinoma cells (Huh7 cells, Hep3B cells) and led to delayed ATP reduction which was associated with increased cell death. These effects could be abrogated by administration of nicotinamide mononucleotide (NMN), the enzyme product of NAMPT. Our results demonstrated a dysregulation of the AMPK/mTOR pathway in hepatocarcinoma cells compared to non-cancerous hepatocytes with a higher expression of mTOR and a lower AMPKα activation in hepatocarcinoma cells. We found that NAMPT inhibition by FK866 significantly activated AMPKα and inhibited the activation of mTOR and its downstream targets p70S6 kinase and 4E-BP1 in hepatocarcinoma cells. Non-cancerous hepatocytes were less sensitive to FK866 and did not show changes in AMPK/mTOR signaling after FK866 treatment. Conclusion: Taken together, these findings reveal an important role of the NAMPT-mediated NAD salvage pathway in the energy homeostasis of hepatocarcinoma cells and suggest NAMPT inhibition as a potential treatment option for HCC. - Highlights: • FK866 increases cell death in p53-deficient hepatocarcinoma cells. • AMPK/mTOR signaling is dysregulated in hepatocarcinoma cells. • FK866-induced NAMPT inhibition activates AMPK

  16. Nebula around R Corona Borealis

    CERN Document Server

    Rao, N Kameswara

    2011-01-01

    The star R Corona Borealis (R CrB) shows forbidden lines of [O II], [N II], and [S II] during the deep minimum when the star is fainter by about 8 to 9 magnitudes from normal brightness, suggesting the presence of nebular material around it. We present low and high spectral resolution observations of these lines during the ongoing deep minimum of R CrB, which started in July 2007. These emission lines show double peaks with a separation of about 170 km/s. The line ratios of [S II] and [O II] suggest an electron density of about 100 cm$^{-3}$. We discuss the physical conditions and possible origins of this low density gas. These forbidden lines have also been seen in other R Coronae Borealis stars during their deep light minima and this is a general characteristic of these stars, which might have some relevance to their origins.

  17. Effects of FK506 on rat thymic epithelial cells; immunohistochemical study.

    Science.gov (United States)

    Takai, K; Tokuda, N; Sawada, T; Fujikura, Y; Jojima, K; Sakatoku, J; Fukumoto, T

    1992-06-01

    The effects of FK506, a new immunosuppressive agent, on the rat thymus were investigated using the immunoperoxidase technique and flow cytofluorometry using monoclonal antibodies. Flow cytometric analysis of the thymus revealed that the proportion of cells labelled positively with OX7 (Thy-1 antigen), OX8 (CD8, T cytotoxic/suppressor cells) and W3/25 (CD4, T helper cells and macrophages) increased following treatment, with FK506, 1 mg/kg body weight for 14 days. A marked reduction of the thymic medulla following treatment was clearly demonstrated by staining with OX18 (MHC class I) and OX6 (MHC class II). Changes produced by FK506 were also observed in the cortical area of the thymus, being especially marked in the subcapsular area and around the blood vessels by staining with OX6, PKK-1 (alpha-cytokeratin), AB-1040 (type IV collagen), and AB-1220 (laminin). Eventually FK506 treatment resulted in patchy reduction of OX-6, PKK-1, AB-1040 and AB-1220 positive area in the cortex. This evidence suggests that FK506 may impair the thymic microenvironment and subsequently disturb the thymocyte maturation.

  18. Synthesis of Orthogonally Reactive FK506 Derivatives via Olefin Cross Metathesis

    Science.gov (United States)

    Marinec, Paul S.; Evans, Christopher G.; Gibbons, Garrett S.; Tarnowski, Malloree A.; Overbeek, Daniel L.; Gestwicki, Jason E.

    2009-01-01

    Chemical inducers of dimerization (CIDs) are employed in a wide range of biological applications, to control protein localization, modulate protein-protein interactions and improve drug lifetimes. These bifunctional chemical probes are assembled from two synthetic modules, which each provide affinity for a distinct protein target. FK506 and its derivatives are often employed as modules in the syntheses of these bifunctional constructs, owing to the abundance and favorable distribution of their target, FK506-binding protein (FKBP). However, the structural complexity of FK506 necessitates multi-step syntheses and/or multiple protection-deprotection schemes prior to installation into CIDs. In this work, we describe an efficient, one-step synthesis of FK506 derivatives through a selective, microwave-accelerated, cross metathesis diversification step of the C39 terminal alkene. Using this approach, FK506 is modified with an array of functional groups, including primary amines and carboxylic acids, which make the resulting derivatives suitable for the modular assembly of CIDs. To illustrate this idea, we report the synthesis of a heterobifunctional HIV protease inhibitor. PMID:19643614

  19. Process optimization by use of design of experiments: Application for liposomalization of FK506.

    Science.gov (United States)

    Toyota, Hiroyasu; Asai, Tomohiro; Oku, Naoto

    2017-03-07

    Design of experiments (DoE) can accelerate the optimization of drug formulations, especially complexed formulas such as those of drugs, using delivery systems. Administration of FK506 encapsulated in liposomes (FK506 liposomes) is an effective approach to treat acute stroke in animal studies. To provide FK506 liposomes as a brain protective agent, it is necessary to manufacture these liposomes with good reproducibility. The objective of this study was to confirm the usefulness of DoE for the process-optimization study of FK506 liposomes. The Box-Behnken design was used to evaluate the effect of the process parameters on the properties of FK506 liposomes. The results of multiple regression analysis showed that there was interaction between the hydration temperature and the freeze-thaw cycle on both the particle size and encapsulation efficiency. An increase in the PBS hydration volume resulted in an increase in encapsulation efficiency. Process parameters had no effect on the ζ-potential. The multiple regression equation showed good predictability of the particle size and the encapsulation efficiency. These results indicated that manufacturing conditions must be taken into consideration to prepare liposomes with desirable properties. DoE would thus be promising approach to optimize the conditions for the manufacturing of liposomes.

  20. EFFECT OF FK224 ON THE BRONCHOCONSTRICTION INDUCED BY ISOCAPNIC HYPERPNEA IN GUINEA PIGS

    Institute of Scientific and Technical Information of China (English)

    陶梦非; 梁永杰

    2005-01-01

    Objective To evaluate effect of Neurokinin receptor antagonist on the prevention from hyperpnea-induced bronchoconstriction using a dual Neurokinin receptor antagonist FK224. Methods 12 pathogenfree Hartley guinea pigs were divided into two groups randomly: Dimethyl sulfoxide (DMSO) control group (n =6)and FK224 group (n =6). Guinea pigs were anesthetized with pentobarbital sodium. A cervical tracheostomy was performed and a polyethylene tube was inserted into the trachea. After measuring baseline value of the lung resistance (RL) and dynamic compliance of respiratory system (Cdyn) , DMSO (0. 3ml/kg) and FK224 ( 1mg/kg) were administered by injection through jugular vein respectively. A rodent respirator with dry 5% CO2-95% O2 mixture at room temperature provided mechanical ventilation ( VT 8ml/animal, 100breaths/min ) for 5min. RL and Cdyn of 2groups were measured after isocapnic hyperpnea challenge. Results In DMSO control group, isocapnic hyperpnea of dry gas elicited a marked increase in RL and decrease in Cdyn. RL and Cdyn of FK224 group did not change significantly. Conclusion FK224 can inhibit the increase in RL and decrease in Cdyn caused by isocapnic hyperpnea in guinea pigs. And antagonists of tachykinins receptors might have effect on prophylaxis and treatment in exercise-induced asthma.

  1. Research on Nanosecond Pulse Corona Discharge Attenuation

    Institute of Scientific and Technical Information of China (English)

    HE Zheng-hao; XU Huai-li; BAI Jing; YU Fu-sheng; HU Feng; LI Jin

    2007-01-01

    A line-to-plate reactor was set-up in the experimental study on the application of nanosecond pulsed corona discharge plasma technology in environmental pollution control.Investigation on the attenuation and distortion of the amplitude of the pulse wave front and the discharge image as well as the waveform along the corona wire was conducted.The results show that the wave front decreases sharply during the corona discharge along the corona wire.The higher the amplitude of the applied pulse is,the more the amplitude of the wave front decreased.The wave attenuation responds in a lower corona discharge inversely.To get a higher efficiency of the line-to-plate reactor a sharp attenuation of the corona has to be considered in practical design.

  2. Spectropolarimetry of Solar Corona during Solar Eclipses

    Science.gov (United States)

    Qu, Zhongquan

    2017-08-01

    We present the results from spectropolarimetry of solar corona. These observations were conducted during solar eclipses in 2008 China, 2013 Gabon, and probably 2017 United States of America respectively. From the former two observations, it is shown that the patterns of linear polarization of radiation from the solar corona are very abundant, and the abundance may be related to the complexity of mass motions and magnetic configuration in the corona. And the spectropolarimetry during solar eclipses may open a new window to probe precisely the physical features of the local corona, especially its magnetic configuration.

  3. Graviton propagator asymptotics and the classical limit of ELPR/FK spin foam models

    CERN Document Server

    Mikovic, Aleksandar

    2011-01-01

    We study the classical limit of ELPR/FK spin foam models by computing the large-distance asymptotics of the spin foam graviton propagator. This is done by analyzing the large-spin asymptotics of the boundary spin-network wavefunction which corresponds to a flat space. By using the stationary phase method we determine the wavefunction asymptotics, which then determines the large-distance asymptotics of the corresponding graviton propagator. We show that the graviton propagator behaves for large distances as the inverse distance to the fourth power, which implies that general relativity is not the classical limit of the ELPR/FK spin foam models. Our result is a direct consequence of the large-spin asymptotics of the ELPR/FK spin-foam vertex amplitude and we show that the vertex amplitude can be modified such that the new amplitude has the desired asymptotics.

  4. FK1706, a novel non-immunosuppressant neurophilin ligand, ameliorates motor dysfunction following spinal cord injury through its neuroregenerative action.

    Science.gov (United States)

    Yamaji, Takayuki; Yamazaki, Shunji; Li, Jiyao; Price, Raymond D; Matsuoka, Nobuya; Mutoh, Seitaro

    2008-09-04

    Injured spinal cord axons fail to regenerate in part due to a lack of trophic support. While various methods for replacing neurotrophins have been pursued, clinical uses of these methods face significant barriers. FK1706, a non-immunosuppressant neurophilin ligand, potentiates nerve growth factor signaling, suggesting therapeutic potential for functional deficits following spinal cord injury. Here, we demonstrate that FK1706 significantly improves behavioral outcomes in animal models of spinal cord hemisection and contusion injuries in rats. Furthermore, we show that FK1706 is effective even if administration is delayed until 1 week after injury, suggesting that FK1706 has a reasonable therapeutic time-window. Morphological analysis of injured axons in the dorsal corticospinal tract showed an increase in the radius and perimeter of stained axons, which were reduced by FK1706 treatment, suggesting that axonal swelling and retraction balls observed in injured spinal cord were improved by the neurotrophic effect of FK1706. Taken together, FK1706 improves both behavioral motor function and the underlying morphological changes, suggesting that FK1706 may have therapeutic potential in meeting the significant unmet needs in spinal cord injury.

  5. Generation of effector T cells in Hymenolepis nana-infected, FK-506-treated BALB/c mice.

    Science.gov (United States)

    Asano, K; Matsuo, S; Okamoto, K

    1995-05-01

    FK-506 administered into mice daily at a dose of 10.0 mg/kg (but not 1.0 and 5.0 mg/kg) caused suppression of protective immunity to Hymenolepis nana, when the agent was injected intraperitoneally during the induction phase of protective immunity. Daily administration of 10.0 mg/kg FK-506, during the course of larval development from challenge, also suppressed protective immunity. Inhibition of protective immunity was only observed in mice that received FK-506 for 6 days at a daily dose of 10.0 mg/kg and were challenged 24 h after the final FK-506 injection. FK-506 did not inhibit formation of effector cells that mediate delayed-type hypersensitivity (DTH) to H. nana egg antigen when the agent was administered intraperitoneally at a dose of 10.0 mg/kg/day for 6 days before cell preparation. However, FK-506 did inhibit DTH effector cell activation when cells prepared from infected, saline-injected mice were transferred into 10.0 mg/kg FK-506-treated recipient mice. These results strongly indicate that FK-506 cannot inhibit the generation of effector cells but will suppress their function in vivo.

  6. Effects of long-term FK506 administration on functional and histopathological outcome after spinal cord injury in adult rat.

    Science.gov (United States)

    Saganová, Kamila; Orendácová, Judita; Sulla, Igor; Filipcík, Peter; Cízková, Dása; Vanický, Ivo

    2009-09-01

    FK506 (tacrolimus), a potent immunosuppressive drug primarily used for reduction of allograft rejection in organ transplantation, also offers neuroprotection after central nervous system injury. FK506-mediated immunosuppression and neuroprotection may occur through different mechanisms that could affect neurological recovery and the severity of spinal lesions where cells transplantation therapy is combined with FK506 application. We assessed effects of long-term FK506 administration using the same dose regiment (1 mg/kg/day for 6 weeks) as is used in spinal cord transplantation studies following a balloon-compression induced spinal cord injury (SCI). Body weight and locomotor recovery quantified by the BBB (Basso-Beattie-Bresnehan) locomotor rating scale were evaluated for up to 42 days post-injury. The area of the preserved spinal cord tissue within a 13 mm segment of the spinal cord (lesion epicenter and 6 mm rostral-caudal) was examined histologically. The results showed no significant effects of FK506 on spinal cord tissue sparing or improvement of locomotor recovery. However, body weight fell significantly (P < 0.05) with FK506 treatment when compared with placebo from day 7 until sacrifice. In our experimental design, long-term FK506 treatment did not affect the parameters of outcome following balloon-compression SCI in the rat; however, multiple effects of FK506 should be taken into account when evaluating the outcomes in transplantation studies.

  7. TRACER STUDY FK UNAND 2008 : PERSEPSI ALUMNI TERHADAP PELAKSANAAN PENDIDIKAN KEDOKTERAN DI FAKULTAS KEDOKTERAN UNIVERSITAS ANDALAS

    Directory of Open Access Journals (Sweden)

    Yulistini Yulistini

    2010-09-01

    Full Text Available AbstrakTracer Study adalah penelitian yang menghimpun informasi tentang sebaran para alumni dan berbagai masukan yang dapat membantu pengembangan kurikulum dan proses pembelajaran di Fakultas Kedokteran Universitas Andalas (FK Unand.Penelitian tracer study di FK Unand 2008 menggunakan pendekatan kuantitatif dengan metode deskriptif analitik. Respondennya adalah alumni FK Unand yang dipilih secara purposive random sampling, yaitu berdasarkan keikutsertaan kegia-tan ilmiah dan kegiatan lainnya di FK Unand tahun 2008.Hasil penelitian menunjukkan persentase responden yang puas dan tidak puas terhadap pelayanan akademik sebanyak 55,5% dan 45,5% dari 124 responden. 61,9% responden merasa puas terhadap pendidikan preklinik dan 50,4% merasa puas terhadap pendidikan klinik. Untuk penilaian kompetensi berdasarkan persepsi responden menunjukkan 66,7% merasa kompeten saat menyelesaikan pendidikan. Uji bivariant menunjukkan hubungan bermakna antara kepuasan terhadap pendidikan preklinik dan klinik, tahun masuk dan jenis kelamin terhadap kompetensi (p<0.05.Kesimpulan adalah sebagian besar responden merasa puas terhadap pelayanan akademik dan pendidikan preklinik. Persentase ketidakpuasan terhadap pen-didikan klinik hanya sedikit lebih tinggi dari pada yang puas. Terdapat hubungan yang bermakna antara kepuasan terhadap pendidikan preklinik, klinik, tahun masuk, dan gender terhadap persepsi responden terhadap kompetensi mereka.Kata kunci :tracer study, alumni, tahun masuk, pre klinik, klinik, kompetensiAbstractTracer Study is a research that gather information about the distribution of the alumni and the various inputs that may help the development of curriculum and learning process in the Faculty of medicine Andalas University (FK Unand Tracer studies FK Unand 2008 using a quantitative approach with a descriptiveARTIKEL PENELITIAN168analytical method. Respondents are FK Unand’s graduates that selected by purposively random sampling, who followed FK Unand

  8. CORONA

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    今年的深圳服交会上,粉红嫩绿大肆张扬,在一片娇嫩中,冷色调的黑白配以热情的红反而特别耀眼却不失深刻,1号馆里,CORONA以“经典与激情的碰撞”为主题,在原有的黑白经典的基础上,加进了红色.

  9. 改性剂FK-316在低盐染色中的应用%Low-salt reactive dyeing of cotton modified with FK-316

    Institute of Scientific and Technical Information of China (English)

    李瀚宇; 王冬生; 齐文玉

    2011-01-01

    The modification is applied to cotton knitted fabric with cationic agent FK-316, and then reactive dyeing with low-salt is carried out. The optimal conditions of modification and low-salt dyeing are settled. The modifying process is modifier FK-316 5%(omf) ,pH value 9.0,holding 20 min at 70℃. The low-salt dyeing process is reactive dye 1 %(omf) .sodium sulfate 20 g/L, liquor ratio 1 :15 ~ 1 :20,dyeing 50 min at 60 ℃.fixing for 50 min with 20 g/L soda ash. When the amount of the dye is equal to or less than 2%, the salt dosage can be reduced to the 1/3 of that in conventional dyeing. The dyeing depth and color fastness are the same with those in conventional dyeing with salt.%对纯棉针织物先采用阳离子改性剂FK-316改性处理,再实施活性染料低盐染色,优化改性处理和低盐染色工艺条件.改性工艺:改性剂FK-316质量分数5%(omf),pH值9.0,70℃保温处理20 min;低盐染色工艺:染料1%(omf),元明粉20 g/L,浴比1∶15~1∶20,染色温度60℃,保温染色50 min,纯碱20 g/L,固色时间50min.阳离子改性剂FK-316应用于活性染料低盐染色时,当染料用量在2%及以下时(中、浅色),盐用量可以降到常规染色盐用量的1/3以下,达到有盐染色相同的染色深度和染色牢度.

  10. Establishment and characterization of a new feline mammary cancer cell line, FkMTp.

    Science.gov (United States)

    Borges, Ana; Adega, Filomena; Chaves, Raquel

    2016-08-01

    Studies on tumours in domestic animals are believed to greatly contribute to a better understanding of similar diseases in humans. Comparative studies have shown that feline mammary carcinomas share important features with human breast cancers, including a similar biological behaviour and histological appearance. In the present study we have established and characterized at different cellular levels one feline mammary cancer cell line, FkMTp, derived from a cat mammary carcinoma. The FkMTp cell line revealed to be a promising resource and tool to study tumour microevolution and all the mechanisms and processes involved in carcinogenesis from the tumour (primary culture) to the immortalized cell line. Several assays were conducted to assess the growth behaviour, differentiated morphology, anchorage independent growth in soft agar, wound-healing invasion and migration of the cell line across time (from the primary culture until the 160th passage). FkMTp revealed increased levels of anchorage independence, migration and invasion according to the course of time as well as different numbers of ploidy. These results demonstrate and validate the in vitro tumorigenicity of the FkMTp cell line. During the cell line establishment, it was cryopreserved approximately every six passages, including the tumour primary culture, allowing now the possibility to access almost any specific momento of the tumour progression.

  11. Effects of tacrolimus (FK506) on sciatic nerve regeneration in rats

    Institute of Scientific and Technical Information of China (English)

    Weiguo Zhang; Decheng Lü; Shouyu Wang; Chongyang Fu

    2009-01-01

    BACKGROUND: Tacrolimus (FK506) protects peripheral nerves located in damaged regions by inhibiting T lymphocyte proliferation and activation.OBJECTIVE: To evaluate the effect of FK506 on promoting regeneration of rat sciatic nerve. DESIGN, TIME AND SETTING: A randomized, controlled, animal study was performed at the Laboratory of the Department of Orthopedic Surgery, Dalian Medical University, China, from September 2007 to September 2008.MATERIALS: A total of 60 adult, male, Sprague-Dawley rats were equally and randomly divided into model, local administration and systemic administration groups. All rats received a neurotomy of bilateral sciatic nerves to establish models of nerve regeneration chambers. The powder and injection of FK506 were supplied by Fujisawa Pharmaceutical, Japan.METHODS: The regeneration chambers of the model group were infused with 0.2 mL saline. The systemic group were injected with 0.2 mL saline, followed by daily subcutaneous injections of FK506 (1 mg/kg), for 14 days. The local administration group was infused with 0.2 mL FK506 (1 μg/mL).MAIN OUTCOME MEASURES: Local immune response was observed using hematoxylin-eosin staining. Myelinated nerve fiber number, myelin sheath and nerve fiber thickness were observed using toluidine blue staining. Wet weight of gastrocnemius was evaluated. Compound muscle action potential amplitude, latency, and conduction time were recorded, and motor nerve conduction velocity was calculated using electrophysiology.RESULTS: The total number of myeiinated nerve fibers in the local and systemic administration groups was significantly higher than in the model group. The density of myelinated nerve fibers, myelin sheath thickness and mean axon diameter were significantly increased in the systemic administration group compared with the model group (P < 0.05). Lymphocyte infiltration was decreased in the local and systemic administration groups compared with the model group. The wet weight of rat gastrocnemius in

  12. The protein corona of circulating PEGylated liposomes.

    Science.gov (United States)

    Palchetti, Sara; Colapicchioni, Valentina; Digiacomo, Luca; Caracciolo, Giulio; Pozzi, Daniela; Capriotti, Anna Laura; La Barbera, Giorgia; Laganà, Aldo

    2016-02-01

    Following systemic administration, liposomes are covered by a 'corona' of proteins, and preserving the surface functionality is challenging. Coating the liposome surface with polyethylene glycol (PEG) is the most widely used anti-opsonization strategy, but it cannot fully preclude protein adsorption. To date, protein binding has been studied following in vitro incubation to predict the fate of liposomes in vivo, while dynamic incubation mimicking in vivo conditions remains largely unexplored. The main aim of this investigation was to determine whether shear stress, produced by physiologically relevant dynamic flow, could influence the liposome-protein corona. The corona of circulating PEGylated liposome was thoroughly compared with that formed by incubation in vitro. Systematic comparison in terms of size, surface charge and quantitative composition was made by dynamic light scattering, microelectrophoresis and nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS). Size of coronas formed under static vs. dynamic incubation did not appreciably differ from each other. On the other side, the corona of circulating liposomes was more negatively charged than its static counterpart. Of note, the variety of protein species in the corona formed in a dynamic flow was significantly wider. Collectively, these results demonstrated that the corona of circulating PEGylated liposomes can be considerably different from that formed in a static fluid. This seems to be a key factor to predict the biological activity of a liposomal formulation in a physiological environment.

  13. Magnetohydrostatic modelling of stellar coronae

    CERN Document Server

    MacTaggart, David; Neukirch, Thomas; Donati, Jean-Francois

    2015-01-01

    We introduce to the stellar physics community a method of modelling stellar coronae that can be considered to be an extension of the potential field. In this approach, the magnetic field is coupled to the background atmosphere. The model is magnetohydrostatic (MHS) and is a balance between the Lorentz force, the pressure gradient and gravity. Analytical solutions are possible and we consider a particular class of equilibria in this paper. The model contains two free parameters and the effects of these on both the geometry and topology of the coronal magnetic field are investigated. A demonstration of the approach is given using a magnetogram derived from Zeeman-Doppler imaging of the 0.75 M$_{\\odot}$ M-dwarf star GJ 182.

  14. A guide to the solar corona

    CERN Document Server

    Billings, Donald E

    1966-01-01

    A Guide to the Solar Corona is specifically directed to the space scientist or engineer who is not a specialist in solar physics, but whose work requires a fairly detailed knowledge of the corona. It is hoped that the material may prove useful to most graduate students in astrophysics, while solar physicists may find some topics of interest and value to them. The book contains 12 chapters and begins with three descriptive chapters that provide the casual reader with a concept of the corona as it is evident through more or less direct observation. Topics covered include the development of coron

  15. Nanoflare heating model for collisionless solar corona

    Indian Academy of Sciences (India)

    U L VISAKH KUMAR; BILIN SUSAN VARGHESE; P J KURIAN

    2017-02-01

    The problem of coronal heating remains one of the greatest unresolved problems in space science. Magnetic reconnection plays a significant role in heating the solar corona. When two oppositely directed magnetic fields come closer to form a current sheet, the current density of the plasma increases due to which magnetic reconnection and conversion of magnetic energy into thermal energy takes place. The present paper deals with a model for reconnection occurring in the solar corona under steady state in collisionless regime. The model predicts that reconnection time in the solar corona varies inversely with the cube of magnetic field and varies directly with the Lindquist number. Our analysis shows that reconnections are occurring within a time interval of600 s in the solar corona, producing nanoflares in the energy range $10^{21}–10^{23}$ erg/s which matches with Yohkoh X-ray observations.

  16. Nanoflare heating model for collisionless solar corona

    Science.gov (United States)

    Visakh Kumar, U. L.; Varghese, Bilin Susan; Kurian, P. J.

    2017-02-01

    The problem of coronal heating remains one of the greatest unresolved problems in space science. Magnetic reconnection plays a significant role in heating the solar corona. When two oppositely directed magnetic fields come closer to form a current sheet, the current density of the plasma increases due to which magnetic reconnection and conversion of magnetic energy into thermal energy takes place. The present paper deals with a model for reconnection occurring in the solar corona under steady state in collisionless regime. The model predicts that reconnection time in the solar corona varies inversely with the cube of magnetic field and varies directly with the Lindquist number. Our analysis shows that reconnections are occurring within a time interval of 600 s in the solar corona, producing nanoflares in the energy range 10 21-10 23 erg /s which matches with Yohkoh X-ray observations.

  17. Global MHD Models of the Solar Corona

    Science.gov (United States)

    Suess, S. T.; Rose, Franklin (Technical Monitor)

    2001-01-01

    Global magnetohydrodynamic (MHD) models of the solar corona are computationally intensive, numerically complex simulations that have produced important new results over the past few years. After a brief overview of how these models usually work, I will address three topics: (1) How these models are now routinely used to predict the morphology of the corona and analyze Earth and space-based remote observations of the Sun; (2) The direct application of these models to the analysis of physical processes in the corona and chromosphere and to the interpretation of in situ solar wind observations; and (3) The use of results from global models to validate the approximations used to make detailed studies of physical processes in the corona that are not otherwise possible using the global models themselves.

  18. Progress of Solar Corona Study in China

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xinhua; SONG Wenbin

    2008-01-01

    Solar corona study is an important aspect of space weather research.In recent years,great achieVements have been acquired on the solar corona study by the space physics group of China.This paper gives a brief outline of these progresses that have been made during 2006--2008.This kind of research includes observational study of the corona,theoretical investigations,statistical analysis based on a large number of data sets,numerical method for MHD modeling,numerical study of space weather events,and prediction methods for the complicated processes originating from the solar corona.Each is given as a separate part in the following.

  19. FK506 “RESCUE” FOR RESISTANT REJECTION OF RENAL ALLOGRAFTS UNDER PRIMARY CYCLOSPORINE IMMUNOSUPPRESSION1

    Science.gov (United States)

    Jordan, Mark L.; Shapiro, Ron; Vivas, Carlos A.; Scantlebury, Velma P.; Rhandhawa, Parmjeet; Carrieri, Giuseppe; McCauley, Jerry; Demetris, A.J.; Tzakis, Andreas; Fung, John J.; Simmons, Richard L.; Hakala, Thomas R.; Starzl, Thomas E.

    2010-01-01

    Seventy-seven patients with ongoing acute rejection on initial CsA therapy were converted to FK506 to attempt graft salvage. Fifty-nine patients had undergone primary transplantation and 18 had been retransplanted; there were 52 cadaveric and 25 living-donor transplants. The indications for conversion to FK506 were ongoing, biopsy-confirmed rejection in all patients, including vascular rejection in 20. The median interval to rescue was 2 months (range 2 weeks to 36 months) after transplantation. Sixty-one of the 77 patients (79%) had already received one or more courses of an antilymphocyte preparation (OKT3: n=33; ALG or ATG: n=l; OKT3+ALG/ATG: n=27). Of the 77 patients, 57 (74%) have been successfully rescued and still have functioning grafts with a mean follow-up of 14 months, with a mean serum creatinine of 2.35±0.97 mg/dl. Eighteen patients were already dialysis-dependent at the time of conversion to FK506; of these, 9 (50%) were successfully salvaged and have a mean serum creatinine of 2.3 mg/dl. Of the 61 patients previously treated with antilymphocyte preparations, 48 (79%) were rescued. In those salvaged, prednisone doses have been lowered from 22.2±7.2 mg/day preconversion to 7.5±5.6 mg/day postconversion, and 12 patients are on FK506 monotherapy. In nondiabetics, mean serum glucose was 101.4±20.5 mg/dl preconversion and 93.2±22 postconversion (P=0.07), uric acid 7.3±2.3 and 7.1±1.5 mg/dl (P=0.53), and triglycerides 199.2±101.6 and 167.2±106.4 mg/dl (P=0.06). Cholesterol levels were significantly lower following FK conversion (207.7±46.5 mg/dl pre. vs. 188.3±39.7 post., P=0.007). FK506 is capable of salvaging renal allografts with ongoing acute rejection on CsA therapy, even when antilymphocyte preparations have been ineffective. PMID:7512293

  20. Dynamics of the Transition Corona

    Science.gov (United States)

    Masson, Sophie; McCauley, Patrick; Golub, Leon; Reeves, Katharine K.; DeLuca, Edward E.

    2014-01-01

    Magnetic reconnection between the open and closed magnetic fields in the corona is believed to play a crucial role in the corona/heliosphere coupling. At large scale, the exchange of open/closed connectivity is expected to occur in pseudo-streamer (PS) structures. However, there is neither clear observational evidence of how such coupling occurs in PSs, nor evidence for how the magnetic reconnection evolves. Using a newly developed technique, we enhance the off-limb magnetic fine structures observed with the Atmospheric Imaging Assembly and identify a PS-like feature located close to the northern coronal hole. We first identify that the magnetic topology associated with the observation is a PS, null-point (NP) related topology bounded by the open field. By comparing the magnetic field configuration with the extreme ultraviolet (EUV) emission regions, we determined that most of the magnetic flux associated with plasma emission are small loops below the PS basic NP and open field bounding the PS topology. In order to interpret the evolution of the PS, we referred to a three-dimensional MHD interchange reconnection modeling the exchange of connectivity between small closed loops and the open field. The observed PS fine structures follow the dynamics of the magnetic field before and after reconnecting at the NP obtained by the interchange model. Moreover, the pattern of the EUV plasma emission is the same as the shape of the expected plasma emission location derived from the simulation. These morphological and dynamical similarities between the PS observations and the results from the simulation strongly suggest that the evolution of the PS, and in particular the opening/closing of the field, occurs via interchange/slipping reconnection at the basic NP of the PS. Besides identifying the mechanism at work in the large-scale coupling between the open and closed fields, our results highlight that interchange reconnection in PSs is a gradual physical process that differs

  1. Effect of Topical FK506 Used alone or Combined with Keratoplasty on Patients with Recurrent Mooren's Corneal Ulcer

    Institute of Scientific and Technical Information of China (English)

    Hanping Xie; Jiaqi Chen; Yueshen Lin; Yongming Liu; Chentian Ye; Shiyou Zhou

    2006-01-01

    Purpose: To evaluate the efficacy of topical 0.1% FK506 used alone or combined with keratoplasty on patients with recurrent Mooren's ulcer.Methods: This is a retrospective interventional consecutive case series. Nine patients(15 eyes) with recurrent Mooren's ulcer were treated with topical 0.1% FK506 alone or combined with keratoplasty. Two eyes with ulcers involving less than half the corneal limbus were treated with topical 0.1% FK506. Of the other 13 eyes with ulcers involving more than half the limbus, twelve were treated with excision of the ulcer and adjacent conjunctiva combined with lamellar keratoplasty. One eye with a central impending corneal perforation was treated with penetrating keratoplasty.Topical0.1% FK506 was given post-operatively to all thirteen eyes after re-epithelia-lisation of the cornea. FK506 levels in the surgically resected cornea and conjunctiva of the operated eyes were measured using enzyme immunoassay procedures. Twelve patients(17 eyes) with recurrent Mooren's ulcer treated with lamellar keratoplasty combined with topical 0.1% dexamethasone were taken as the control. The main measure of the outcome was the recurrence of Mooren's ulcer in the patients.Results: Nine patients (15 eyes) with recurrent Mooren's ulcer were all successfully treated. Vision in 5 eyes improved by two lines or better after treatment. No recurrence was observed during the follow up period of 12 to 22 months. After topical application of 0.1% FK506, concentrations of 30~350 ng/g of FK506 were found in the cornea and conjunctiva. Seven eyes of Mooren's ulcer in the control group recurred during the follow up period. Conclusion: Topical 0.1% FK506 used alone or combined with keratoplasty is a safe and effective therapy for patients with recurrent Mooren's ulcer.

  2. Comparative proteomic and metabolomic analysis of Streptomyces tsukubaensis reveals the metabolic mechanism of FK506 overproduction by feeding soybean oil.

    Science.gov (United States)

    Wang, Jun; Liu, Huanhuan; Huang, Di; Jin, Lina; Wang, Cheng; Wen, Jianping

    2017-03-01

    FK506 (tacrolimus) is a 23-membered polyketide macrolide that possesses powerful immunosuppressant activity. In this study, feeding soybean oil into the fermentation culture of Streptomyces tsukubaensis improved FK506 production by 88.8%. To decipher the overproduction mechanism, comparative proteomic and metabolomic analysis was carried out. A total of 72 protein spots with differential expression in the two-dimensional gel electrophoresis (2-DE) were identified by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF-MS), and 66 intracellular metabolites were measured by gas chromatography-mass spectrometer (GC-MS). The analysis of proteome and metabolome indicated that feeding soybean oil as a supplementary carbon source could not only strengthen the FK506 precursor metabolism and energy metabolism but also tune the pathways related to transcriptional regulation, translation, and stress response, suggesting a better intracellular metabolic environment for the synthesis of FK506. Based on these analyses, 20 key metabolites and precursors of FK506 were supplemented into the soybean oil medium. Among them, lysine, citric acid, shikimic acid, and malonic acid performed excellently for promoting the FK506 production and biomass. Especially, the addition of malonic acid achieved the highest FK506 production, which was 1.56-fold of that in soybean oil medium and 3.05-fold of that in initial medium. This report represented the first comprehensive study on the comparative proteomics and metabolomics applied in S. tsukubaensis, and it would be a rational guidance to further strengthen the FK506 production.

  3. Tacrolimus (FK506 reduces ischemia-induced hippocampal damage in rats: a 7- and 30-day study

    Directory of Open Access Journals (Sweden)

    F. Giordani

    2003-04-01

    Full Text Available The neuroprotective effect of the immunosuppressant agent FK506 was evaluated in rats after brain ischemia induced for 15 min in the 4-vessel occlusion model. In the first experimental series, single doses of 1.0, 3.0 or 6.0 mg FK506/kg were given intravenously (iv immediately after ischemia. In the second series, FK506 (1.0 mg/kg was given iv at the beginning of reperfusion, followed by doses applied intraperitoneally (ip 6, 24, 48, and 72 h post-ischemia. The same protocol was used in the third series except that all 5 doses were given iv. Damage to the hippocampal field CA1 was assessed 7 or 30 days post-ischemia on three different stereotaxic planes along the septotemporal axis of the hippocampus. Ischemia caused marked neurodegeneration on all planes (P<0.001. FK506 failed to provide neuroprotection to CA1 both when applied iv as a single dose of 1.0, 3.0 or 6.0 mg/kg (experiment 1, and after five iv injections of 1.0 mg/kg (experiment 3. In contrast, the repeated administration of FK506 combining iv plus ip administration reduced CA1 cell death on all stereotaxic planes both 7 and 30 days post-ischemia (experiment 2; P<=0.01. Compared to vehicle alone, FK506 reduced rectal temperature in a dose-dependent manner (P<=0.05; however, this effect did not alter normothermia (37ºC. FK506 reduced ischemic brain damage, an effect sustained over time and apparently dependent on repeated doses and on delivery route. The present data extend previous findings on the rat 4-vessel occlusion model, further supporting the possible use of FK506 in the treatment of ischemic brain damage.

  4. Solution structure of FK506-binding protein 12 from Aedes aegypti.

    Science.gov (United States)

    Chakraborty, Goutam; Shin, Joon; Nguyen, Quoc Toan; Harikishore, Amaravadhi; Baek, Kwanghee; Yoon, Ho Sup

    2012-10-01

    Dengue remains one of the major public concerns as the virus eludes the immune response. Currently, no vaccines or antiviral therapeutics are available for dengue prevention or treatment. Immunosuppressive drug FK506 shows an antimalarial activity, and its molecular target, FK506-binding protein (FKBP), was identified in human Plasmodium parasites. Likewise, a conserved FKBP family protein has also been identified in Aedes aegypti (AaFKBP12), which is expected to play a similar role in the life cycle of Aedes aegypti, the primary vector of dengue virus infection. As FKBPs belong to a highly conserved class of immunophilin family and are involved in key biological regulations, they are considered as attractive pharmacological targets. In this study, we have determined the nuclear magnetic resonance solution structure of AaFKBP12, a novel FKBP member from Aedes aegypti, and presented its structural features, which may facilitate the design of potential inhibitory ligands against the dengue-transmitting mosquitoes.

  5. Self-Energy in the Lorentzian ERPL-FK Spin Foam Model of Quantum Gravity

    CERN Document Server

    Riello, Aldo

    2013-01-01

    We calculate the most divergent contribution to the self-energy (or "melonic") graph in the context of the Lorentzian EPRL-FK Spin Foam model of Quantum Gravity. We find that such a contribution is logarithmically divergent in the cut-off over the SU(2)-representation spins when one chooses the face amplitude guaranteeing the face-splitting invariance of the foam.We also find that the dependence on the boundary data is different from that of the bare propagator. This fact has its origin in the non-commutativity of the EPRL-FK Y-map with the projector onto SL(2,C)-invariant states. In the course of the paper, we discuss in detail the approximations used during the calculations, its geometrical interpretation as well as the physical consequences of our result.

  6. Effects of FK506 on Hippocampal CA1 Cells Following Transient Global Ischemia/Reperfusion in Wistar Rat

    Directory of Open Access Journals (Sweden)

    Zahra-Nadia Sharifi

    2012-01-01

    Full Text Available Transient global cerebral ischemia causes loss of pyramidal cells in CA1 region of hippocampus. In this study, we investigated the neurotrophic effect of the immunosuppressant agent FK506 in rat after global cerebral ischemia. Both common carotid arteries were occluded for 20 minutes followed by reperfusion. In experimental group 1, FK506 (6 mg/kg was given as a single dose exactly at the time of reperfusion. In the second group, FK506 was administered at the beginning of reperfusion, followed by its administration intraperitoneally (IP 6, 24, 48, and 72 hours after reperfusion. FK506 failed to show neurotrophic effects on CA1 region when applied as a single dose of 6 mg/kg. The cell number and size of the CA1 pyramidal cells were increased, also the number of cell death decreased in this region when FK506 was administrated 48 h after reperfusion. This work supports the possible use of FK506 in treatment of ischemic brain damage.

  7. Protective effect of cyclosporin A and FK506 from nitric oxide-dependent apoptosis in activated macrophages

    Science.gov (United States)

    Hortelano, Sonsoles; López-Collazo, Eduardo; Boscá, Lisardo

    1999-01-01

    Activation of macrophages with lipopolysaccharide (LPS) and low doses of interferon-γ (IFN-γ) induced apoptotic death through a nitric oxide-dependent pathway. Treatment of cells with the immunosuppressors cyclosporin A (CsA) or FK506 inhibited the activation-dependent apoptosis. These drugs decreased the up-regulation of p53 and Bax characteristic of activated macrophages. Moreover, incubation of activated macrophages with CsA and FK506 contributed to maintain higher levels of Bcl-2 than in LPS/IFN-γ treated cells. The inhibition of apoptosis exerted by CsA and FK506 in macrophages was also observed when cell death was induced by treatment with chemical nitric oxide donors. Incubation of macrophages with LPS/IFN-γ barely affected caspase-1 but promoted an important activation of caspase-3. Both CsA and FK506 inhibited pathways leading to caspase-3 activation. Moreover, the cleavage of poly(ADP-ribose) polymerase, a well established caspase substrate, was reduced by these immunosuppressive drugs. CsA and FK506 reduced the release of cytochrome c to the cytosol and the activation of caspase-3 in cells treated with nitric oxide donors. These results indicate that CsA and FK506 protect macrophages from nitric oxide-dependent apoptosis and suggest a contribution of the macrophage to innate immunity under conditions of immunosuppression of the host. PMID:10205001

  8. Resistance reversal induced by a combination of fluconazole and tacrolimus (FK506) in Candida glabrata.

    Science.gov (United States)

    Li, Hui; Chen, Zuozhong; Zhang, Caiqing; Gao, Yuan; Zhang, Xiang; Sun, Shujuan

    2015-01-01

    There is an increasing concern about Candida glabrata due to its high isolation frequency in candidiasis recently and notorious drug resistance to fluconazole. Drug combination is one effective approach to counteract drug resistance. This study aimed to test whether a combination of fluconazole and tacrolimus (FK506) had a synergistic effect on C. glabrata, and to seek the potential mechanisms underlying the synergistic effects. In vitro effects of fluconazole and FK506 against C. glabrata with different susceptibilities were investigated by a chequerboard method and a time-kill curve method. The mechanistic studies against the resistant C. glabrata were performed from two aspects: quantification of expression levels of fluconazole resistance genes (ERG11, CDR1, PDH1 and SNQ2) by real-time quantitative PCR and functional assays of drug efflux pumps. The addition of FK506 resulted in a decrease in the MIC of fluconazole from 32 to 8 µg ml(-1) against the dose-dependent susceptible C. glabrata, and from 256 to 16 µg ml(-1) against the resistant C. glabrata, respectively. The synergy was further confirmed by the time-kill assay. The expression levels of the ERG11 and SNQ2 genes were significantly downregulated after exposure to the drug combination, whereas that of the CDR1 gene was significantly upregulated, and no significant change in expression of PDH1 gene was observed. Flow cytometric assays showed that FK506 reduced the efflux of fluconazole. Tacrolimus enhanced the susceptibility of fluconazole against resistant C. glabrata by reducing the expression levels of the ERG11 and SNQ2 genes and inhibiting fluconazole efflux.

  9. Hubungan Faktor Keturunan, Lamanya Bekerja Jarak Dekat, Dengan Miopia Pada Mahasiswa FK USU

    OpenAIRE

    Fatika Sari Hasibuan

    2010-01-01

    Tujuan: untuk mengetahui pengaruh genetik dan lamanya bekerja arak dekat dengan miopia. Metode: penelitian ini dilakukan dengan pengumpulan kuesioner dari 93 orang mahasiswa FK USU yang berisi tentang status kelainan refraksi pada mahasiswa, status kelainan refraksi orang tua mahasiswa, lamanya waktu yang dihabiskan untuk melakukan kegiatan jark dekat ( seperti belajar, membaca untuk hobi, menonton TV, menggunakan komputer) dan waktu yang dihabiskan untuk berada di luar rumah selain untuk...

  10. The NAMPT inhibitor FK866 reverts the damage in spinal cord injury

    Directory of Open Access Journals (Sweden)

    Esposito Emanuela

    2012-04-01

    Full Text Available Abstract Background Emerging data implicate nicotinamide phosphoribosyl transferase (NAMPT in the pathogenesis of cancer and inflammation. NAMPT inhibitors have proven beneficial in inflammatory animal models of arthritis and endotoxic shock as well as in autoimmune encephalitis. Given the role of inflammatory responses in spinal cord injury (SCI, the effect of NAMPT inhibitors was examined in this setting. Methods We investigated the effects of the NAMPT inhibitor FK866 in an experimental compression model of SCI. Results Twenty-four hr following induction of SCI, a significant functional deficit accompanied widespread edema, demyelination, neuron loss and a substantial increase in TNF-α, IL-1β, PAR, NAMPT, Bax, MPO activity, NF-κB activation, astrogliosis and microglial activation was observed. Meanwhile, the expression of neurotrophins BDNF, GDNF, NT3 and anti-apoptotic Bcl-2 decreased significantly. Treatment with FK866 (10 mg/kg, the best known and characterized NAMPT inhibitor, at 1 h and 6 h after SCI rescued motor function, preserved perilesional gray and white matter, restored anti-apoptotic and neurotrophic factors, prevented the activation of neutrophils, microglia and astrocytes and inhibited the elevation of NAMPT, PAR, TNF-α, IL-1β, Bax expression and NF-κB activity. We show for the first time that FK866, a specific inhibitor of NAMPT, administered after SCI, is capable of reducing the secondary inflammatory injury and partly reduce permanent damage. We also show that NAMPT protein levels are increased upon SCI in the perilesional area which can be corrected by administration of FK866. Conclusions Our findings suggest that the inflammatory component associated to SCI is the primary target of these inhibitors.

  11. Optimization of liquid fermentation condition for Bacillus natto FK-3%纳豆芽孢杆菌 FK-3液体发酵条件优化

    Institute of Scientific and Technical Information of China (English)

    赵彩春; 区毅垣; 史宝军

    2016-01-01

    文章旨在研究一株纳豆芽孢杆菌(Bacillus natto)FK-3液体发酵的最佳发酵条件及培养基配方。采用单因素试验以及正交试验,对培养条件如温度、转速、装液量、接种量、初始pH值以及培养基配方的碳源、氮源、无机盐等因素进行研究,试验数据通过SPSS 22软件展开单因素方差分析、正交试验极差分析及方差分析。结果表明,该菌株的最适培养条件是初始pH值为7.5,温度33℃,摇床转速190 r/min,装液量为60 ml/250 ml三角瓶,接种量为4%,种龄是20 h,收获时间为20 h。培养基配方为米糠1.0%,玉米粉1.0%,玉米淀粉2.0%,豆粕4%,酵母膏1.0%,磷酸氢二钠0.1%,硫酸镁0.05%,氯化钙0.05%,硫酸锰0.01%。FK-3在15 L发酵罐中发酵活菌量达1.41×1010 cfu/ml,芽孢数为1.37×1010 cfu/ml,芽孢率为97%。%This experiment was conducted to study the optimization of liquid fermentation condition and medium for a Bacillus natto strain FK-3. The single-factor method and orthogonal experimental method were used to optimize the fermentation condition of initial pH, temperature, rotation speed, in⁃oculation amount and the fermentation medium factors of carbon sources, nitrogen sources and inorgan⁃ic salts. ANOVA and orthogonal test range analysis and variance analysis were conducted by SPSS 22. The result showed the optimization condition for Bacillus natto strain FK-3 are as following: initial pH was 7.5, temperature was 33 ℃, rotation speed was 190 r/min, liquid volume was 60 ml/250 ml, inocu⁃lation amount was 4.0%, fermentation time was 20 h. The optimization medium component are as fol⁃lowing : rice bran 1.0%,corn flour 1.0%,corn starch 2.0%, soybean meal 4.0%, yeast extract 1.0%, Na2HPO4 0.1%, MgSO4 0.05%,CaCl2 0.05%,MnSO4 0.01%. The bacteria number of FK-3 was 1.41 × 1010 cfu/ml when fermentation in 15 L fermenter and spores number was 1.37 × 1010 cfu/ml, The spores rate was 97%.

  12. A search for FK Com candidates using Kepler Space Telescope observations: Analogs of HD 199178

    Science.gov (United States)

    Puzin, V. B.; Savanov, I. S.; Dmitrienko, E. S.

    2017-08-01

    Analysis of collected photometric observations obtained with the Kepler Space Telescope were used to select and study 33 objects with parameters corresponding to those of the FK Com starHD199178; these can be considered candidate stars of this type. In this final study, the four objects with the best light curves, which show the properties of their regular rotational modulation most clearly, were selected for detailed studies. The photometric analysis is based on all data currently available in the Kepler archive (covering almost four years). The rotational periods and estimated parameters of the objects' differential rotation are determined, and the longitudes of the dominant active regions on the surfaces found. For all four stars, the spot coverage is approximately 1% of the visible stellar surface area. The rotational periods and data on the stars'masses and radii fromtheMAST catalog are used to determine the rotation velocities projected onto the line of sight, which ranged from 12 to 21 km/s. Further studies will enable definite conclusions about how these stars are related to FK Com stars. If they are ultimately classified as FK Com stars, this will considerably increase the number of this rare type of star and the also number of rapidly rotating, single, late-type giants.

  13. Complementary analysis of the hard and soft protein corona: sample preparation critically effects corona composition

    Science.gov (United States)

    Winzen, S.; Schoettler, S.; Baier, G.; Rosenauer, C.; Mailaender, V.; Landfester, K.; Mohr, K.

    2015-02-01

    Here we demonstrate how a complementary analysis of nanocapsule-protein interactions with and without application media allows gaining insights into the so called hard and soft protein corona. We have investigated how both human plasma and individual proteins (human serum albumin (HSA), apolipoprotein A-I (ApoA-I)) adsorb and interact with hydroxyethyl starch (HES) nanocapsules possessing different functionalities. To analyse the hard protein corona we used sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and a protein quantitation assay. No significant differences were observed with regards to the hard protein corona. For analysis of the soft protein corona we characterized the nanocapsule-protein interaction with isothermal titration calorimetry (ITC) and dynamic light scattering (DLS). DLS and ITC measurements revealed that a high amount of plasma proteins were adsorbed onto the capsules' surface. Although HSA was not detected in the hard protein corona, ITC measurements indicated the adsorption of an HSA amount similar to plasma with a low binding affinity and reaction heat. In contrast, only small amounts of ApoA-I protein adsorb to the capsules with high binding affinities. Through a comparison of these methods we have identified ApoA-I to be a component of the hard protein corona and HSA as a component of the soft corona. We demonstrate a pronounced difference in the protein corona observed depending on the type of characterization technique applied. As the biological identity of a particle is given by the protein corona it is crucial to use complementary characterization techniques to analyse different aspects of the protein corona.Here we demonstrate how a complementary analysis of nanocapsule-protein interactions with and without application media allows gaining insights into the so called hard and soft protein corona. We have investigated how both human plasma and individual proteins (human serum albumin (HSA), apolipoprotein A

  14. Complementary analysis of the hard and soft protein corona: sample preparation critically effects corona composition.

    Science.gov (United States)

    Winzen, S; Schoettler, S; Baier, G; Rosenauer, C; Mailaender, V; Landfester, K; Mohr, K

    2015-02-21

    Here we demonstrate how a complementary analysis of nanocapsule-protein interactions with and without application media allows gaining insights into the so called hard and soft protein corona. We have investigated how both human plasma and individual proteins (human serum albumin (HSA), apolipoprotein A-I (ApoA-I)) adsorb and interact with hydroxyethyl starch (HES) nanocapsules possessing different functionalities. To analyse the hard protein corona we used sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and a protein quantitation assay. No significant differences were observed with regards to the hard protein corona. For analysis of the soft protein corona we characterized the nanocapsule-protein interaction with isothermal titration calorimetry (ITC) and dynamic light scattering (DLS). DLS and ITC measurements revealed that a high amount of plasma proteins were adsorbed onto the capsules' surface. Although HSA was not detected in the hard protein corona, ITC measurements indicated the adsorption of an HSA amount similar to plasma with a low binding affinity and reaction heat. In contrast, only small amounts of ApoA-I protein adsorb to the capsules with high binding affinities. Through a comparison of these methods we have identified ApoA-I to be a component of the hard protein corona and HSA as a component of the soft corona. We demonstrate a pronounced difference in the protein corona observed depending on the type of characterization technique applied. As the biological identity of a particle is given by the protein corona it is crucial to use complementary characterization techniques to analyse different aspects of the protein corona.

  15. Effects of tacrolimus (FK506) on human insulin gene expression, insulin mRNA levels, and insulin secretion in HIT-T15 cells.

    OpenAIRE

    1996-01-01

    FK506 (tacrolimus) is an immunosuppressive drug which interrupts Ca2+-calmodulin-calcineurin signaling pathways in T lymphocytes, thereby blocking antigen activation of T cell early activation genes. Regulation of insulin gene expression in the beta cell may also involve Ca2+-signaling pathways and FK506 has been associated with insulin-requiring diabetes mellitus during clinical use. The purpose of this study was to characterize the effects of FK506 on human insulin gene transcription, insul...

  16. Direct observation of laser guided corona discharges

    CERN Document Server

    Wang, Tie-Jun; Liu, Yaoxiang; Chen, Na; Liu, Yonghong; Ju, Jingjing; Sun, Haiyi; Wang, Cheng; Lu, Haihe; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2015-01-01

    Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. The high voltage corona discharge can be guided along laser plasma filament, and enhanced through the interaction with laser filaments. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This could be advantageous towards laser assisted leader development in the atmosphere.

  17. FK-16 derived from the anticancer peptide LL-37 induces caspase-independent apoptosis and autophagic cell death in colon cancer cells.

    Directory of Open Access Journals (Sweden)

    Shun X Ren

    Full Text Available Host immune peptides, including cathelicidins, have been reported to possess anticancer properties. We previously reported that LL-37, the only cathelicidin in humans, suppresses the development of colon cancer. In this study, the potential anticancer effect of FK-16, a fragment of LL-37 corresponding to residues 17 to 32, on cultured colon cancer cells was evaluated. FK-16 induced a unique pattern of cell death, marked by concurrent activation of caspase-independent apoptosis and autophagy. The former was mediated by the nuclear translocation of AIF and EndoG whereas the latter was characterized by enhanced expression of LC3-I/II, Atg5 and Atg7 and increased formation of LC3-positive autophagosomes. Knockdown of Atg5 or Atg7 attenuated the cytotoxicity of FK-16, indicating FK-16-induced autophagy was pro-death in nature. Mechanistically, FK-16 activated nuclear p53 to upregulate Bax and downregulate Bcl-2. Knockdown of p53, genetic ablation of Bax, or overexpression of Bcl-2 reversed FK-16-induced apoptosis and autophagy. Importantly, abolition of AIF/EndoG-dependent apoptosis enhanced FK-16-induced autophagy while abolition of autophagy augmented FK-16-induced AIF-/EndoG-dependent apoptosis. Collectively, FK-16 induces caspase-independent apoptosis and autophagy through the common p53-Bcl-2/Bax cascade in colon cancer cells. Our study also uncovered previously unknown reciprocal regulation between these two cell death pathways.

  18. TRIANGLE-SHAPED DC CORONA DISCHARGE DEVICE FOR MOLECULAR DECOMPOSITION

    Science.gov (United States)

    The paper discusses the evaluation of electrostatic DC corona discharge devices for the application of molecular decomposition. A point-to-plane geometry corona device with a rectangular cross section demonstrated low decomposition efficiencies in earlier experimental work. The n...

  19. What Can TRAPPIST-1 Tell Us About Radiation From M-Dwarf Chromospheres And Coronae

    Science.gov (United States)

    Linsky, Jeffrey

    2017-05-01

    The recent discovery of 7 planets orbiting the nearby star TRAPPIST-1 (Gillon et al. Nature 2017) and the discovery that this M8 V host star has very weak chromospheric compared to coronal emission (Bourrier et al. A+A 2017) raises the broader question of the relation of chromospheres to coronae in host stars. This question is important because chromospheric emission, primarily in the Lyman-alpha line, controls photochemical reactions in the outer atmospheres of exoplanets, whereas coronal X-ray emission and associated coronal mass ejections play critical roles in atmospheric mass loss. Both chromospheric and coronal emission from the host star can, therefore, determine whether a planet is habitable. I will show that the amount of emission in the Lyman-alpha line is proportional to that in X-rays for F-K dwarf stars, but that chromospheric emission becomes relatively weak in the early M dwarfs and very weak in the late-M dwarfs such as TRAPPIST-1.Stellar emission lines formed in a star's chromosphere and transition region can be separated into narrow and broad Gaussian components with the broad components formed by microflaring events or high speed flows. I will show how the broad component activity indicator depends on stellar effective temperature and age.I will also describe the results concerning star-planet interactions obtained by MUSCLES Treasury Survey team.

  20. Study of Solar Corona in China

    Institute of Scientific and Technical Information of China (English)

    FENG Xueshang; ZHAO Xinhua

    2006-01-01

    Considerable progress for the study of solar corona physics has been achieved by China's space physics community. It involves the theoretical study of coronal process of solar active phenomena, solar wind origin, acceleration of solar wind and coronal mass ejections, observational and numerical study of these problems and prediction methods of solar eruptive activities (such as flares/CMEs). Here is a brief summary of the progress in this area. Main progress is put upon the following three topics: corona and solar wind, numerical method, prediction method.

  1. Probing the Solar Corona with VLBI

    Science.gov (United States)

    Soja, Benedikt; Sun, Jing; Heinkelmann, Robert; Schuh, Harald; Böhm, Johannes

    2013-04-01

    Radio observations close to the Sun are sensitive to the dispersive effects of the Sun corona. This has been used to determine (among other parameters) the electron density in the corona during solar conjunctions with spacecrafts. Although geodetic Very Long Baseline Interferometry (VLBI) observations close to the Sun have already been performed before 2002 (but suspended afterwards) they have not yet been used for calculations of corona electron densities. Almost 10 years later the International VLBI Service for Geodesy and Astrometry (IVS) decided to schedule twelve 24 hours VLBI sessions in 2011 and 2012 including observations closer than 15 degrees to the heliocenter. Both the recent and the earlier sessions are analysed in order to determine electron densities of the Sun corona. Based on the ionospheric delay corrections derived from two-frequency VLBI measurements, other dispersive effects like instrumental biases and, most important of all, the Earth's ionosphere effects are estimated and then eliminated. The residual delays are used to successfully determine power-law parameters of the electron density of the Sun corona for several of these sessions. In some cases, scheduled observations close to the Sun had failed, making it impossible to derive meaningful results from them. Both, the successful and the lost observations were analysed including external information like Sunspot numbers and flare occurrences. The estimated electron densities were compared to previous models of the Sun corona derived by radio measurements to spacecrafts during solar conjunctions. Our investigations show that it is possible to use geodetic VLBI sessions with observations close to the Sun to determine electron densities of the corona. The success depends on the geometry, i.e. the source position with respect to the Sun, and on the schedule, which can be optimized for such investigations. Unpredictable disturbances at the Sun's surface, such as flares, play also a role. So far

  2. Electric Current Equilibrium in the Corona

    CERN Document Server

    Filippov, Boris

    2013-01-01

    A hyperbolic flux-tube configuration containing a null point below the flux rope is considered as a pre-eruptive state of coronal mass ejections that start simultaneously with flares. We demonstrate that this configuration is unstable and cannot exist for a long time in the solar corona. The inference follows from general equilibrium conditions and from analyzing simple models of the flux-rope equilibrium. A direct consequence of the stable flux-rope equilibrium in the corona are separatrices in the horizontal-field distribution in the chromosphere. They can be recognized as specific "herring-bone structures" in a chromospheric fibril pattern.

  3. Electric Current Equilibrium in the Corona

    Science.gov (United States)

    Filippov, Boris

    2013-04-01

    A hyperbolic flux-tube configuration containing a null point below the flux rope is considered as a pre-eruptive state of coronal mass ejections that start simultaneously with flares. We demonstrate that this configuration is unstable and cannot exist for a long time in the solar corona. The inference follows from general equilibrium conditions and from analyzing simple models of the flux-rope equilibrium. A direct consequence of the stable flux-rope equilibrium in the corona are separatrices in the horizontal-field distribution in the chromosphere. They can be recognized as specific "herring-bone structures" in a chromospheric fibril pattern.

  4. Hot Plasma Flows in the Solar Corona

    Science.gov (United States)

    Shibasaki, K.

    2012-12-01

    The Solar Corona is a non-equilibrium open system. Energy and mass are supplied from the lower atmosphere and flow upwards through the corona into the interplanetary space. Steady state could be possible but not equilibrium state. Temperature of the corona varies depending on solar activities. However, even under very quite state, coronal temperature is still kept around million degrees. Coronal heating mechanisms have to work under such condition. Temperature of plasma is an averaged kinetic energy of random motion of particles. Motion of charged particles in magnetic field generates Lorenz force and particles gyrate around magnetic field lines. Gyration of charged particles generates magnetic moment which is directed anti-parallel to the surrounding magnetic field. This is the origin of diamagnetism of plasma. Each particle can be considered as a small magnet directed opposite to the surrounding magnetic field. When these magnets are put in inhomogeneous magnetic field, they are pushed toward weak field region. In case of open magnetic field region in the solar corona, plasma particles are pushed upwards. If this force (diamagnetic or mirror force) exceeds the gravity force, plasma flows upwards. Magnetic moment of each charged particle in thermal plasma is proportional to temperature and inversely proportional to magnetic field strength. The condition for plasma to flow upwards in an open magnetic field is that the scale length of the change of magnetic field strength is shorter than the hydrostatic scale length, which is determined by temperature and the gravity acceleration. This can be a mechanism to regulate the coronal temperature around million degree. The solar corona is filled with magnetic field, which is rooted at the photosphere in the form of flux tubes. Flux tubes connect directly the corona and the sub-photospheric layer where temperature is higher than the photosphere. Hot plasma, trapped in the flux tubes when they are generated around the bottom

  5. Device for generation of pulsed corona discharge

    Science.gov (United States)

    Gutsol, Alexander F [San Ramon, CA; Fridman, Alexander [Marlton, NJ; Blank, Kenneth [Philadelphia, PA; Korobtsev, Sergey [Moscow, RU; Shiryaevsky, Valery [Moscow, RU; Medvedev, Dmitry [Moscow, RU

    2012-05-08

    The invention is a method and system for the generation of high voltage, pulsed, periodic corona discharges capable of being used in the presence of conductive liquid droplets. The method and system can be used, for example, in different devices for cleaning of gaseous or liquid media using pulsed corona discharge. Specially designed electrodes and an inductor increase the efficiency of the system, permit the plasma chemical oxidation of detrimental impurities, and increase the range of stable discharge operations in the presence of droplets of water or other conductive liquids in the discharge chamber.

  6. Surface degradation of silicone rubber exposed to corona discharge

    OpenAIRE

    Zhu, Yong; Haji, Kenichi; Otsubo, Masahisa; Honda, Chikahisa

    2006-01-01

    This paper describes the surface degradation of unfilled high-temperature vulcanized silicone rubber (HTV-SR)###resulting from creeping corona discharges under atmospheric pressure. In this paper, HTV-SR specimens were exposed to corona###stress generated by a parallel needle-plate electrode system; furthermore, physicochemical analyses were conducted on the surface layer of SR before and after corona discharge treatment. The results showed that the plasma impingement from the corona discharg...

  7. Nanoparticle-protein corona in invertebrate in vitro testing

    DEFF Research Database (Denmark)

    Hayashi, Yuya; Miclaus, Teodora; Scavenius, Carsten;

    2013-01-01

    , and the primary cells were thus exposed to silver nanoparticles with pre-formed corona of serum albumin (a major serum protein). Here we have profiled proteins forming the hard corona around silver nanoparticles (OECD reference materials, 15 nm and 75 nm) using gel electrophoresis techniques to identify proteins...... for evaluation of the protein corona in invertebrate in vitro setting....

  8. A Connection Between Corona and Jet

    Science.gov (United States)

    Kohler, Susanna

    2017-03-01

    The structure immediately around a supermassive black hole at the heart of an active galaxy can tell us about how material flows in and out of these monsters but this region is hard to observe! A new study provides us with clues of what might be going on in these active and energetic cores of galaxies.In- and OutflowsIn active galactic nuclei (AGN), matter flows both in and out. As material flows toward the black hole via its surrounding accretion disk, much of this gas and dust can then be expelled from the vicinity via highly collimated jets.Top: The fraction of X-rays that is reflected decreases as jet power increases. Bottom: the distance between the corona and the reflecting part of the disk increases as jet power increases. [Adapted from King et al. 2017]To better understand this symbiosis between accretion and outflows, we examine whats known as the corona the hot, X-ray-emitting gas thats located in the closest regions around the black hole. But because the active centers of galaxies are generally obscured by surrounding gas and dust, its difficult for us to learn about the structure of these inner regions near the black hole.Where are the X-rays of the corona produced: in the inner accretion flow, or at the base of the jet? How far away is this corona from the disk? And how does the coronas behavior relate to that of the jet?Reflected ObservationsTo address some of these questions, a group of scientists led by Ashley King (Einstein Fellow at Stanford University) has analyzed X-ray observations from NuSTAR and XMM-Newton of over 40 AGN. The team examined the reflections of the X-rays off of the accretion disk and used two measurements to learn about the structure around the black hole:the fraction of the coronas X-rays that are reflected by the disk, andthe time lag between the original and reflected X-rays, which reveals the distance from the corona to the reflecting part of the disk.A visualization of the authors model for an AGN. The accretion disk is

  9. CD73 protein as a source of extracellular precursors for sustained NAD+ biosynthesis in FK866-treated tumor cells.

    Science.gov (United States)

    Grozio, Alessia; Sociali, Giovanna; Sturla, Laura; Caffa, Irene; Soncini, Debora; Salis, Annalisa; Raffaelli, Nadia; De Flora, Antonio; Nencioni, Alessio; Bruzzone, Santina

    2013-09-06

    NAD(+) is mainly synthesized in human cells via the "salvage" pathways starting from nicotinamide, nicotinic acid, or nicotinamide riboside (NR). The inhibition with FK866 of the enzyme nicotinamide phosphoribosyltransferase (NAMPT), catalyzing the first reaction in the "salvage" pathway from nicotinamide, showed potent antitumor activity in several preclinical models of solid and hematologic cancers. In the clinical studies performed with FK866, however, no tumor remission was observed. Here we demonstrate that low micromolar concentrations of extracellular NAD(+) or NAD(+) precursors, nicotinamide mononucleotide (NMN) and NR, can reverse the FK866-induced cell death, this representing a plausible explanation for the failure of NAMPT inhibition as an anti-cancer therapy. NMN is a substrate of both ectoenzymes CD38 and CD73, with generation of NAM and NR, respectively. In this study, we investigated the roles of CD38 and CD73 in providing ectocellular NAD(+) precursors for NAD(+) biosynthesis and in modulating cell susceptibility to FK866. By specifically silencing or overexpressing CD38 and CD73, we demonstrated that endogenous CD73 enables, whereas CD38 impairs, the conversion of extracellular NMN to NR as a precursor for intracellular NAD(+) biosynthesis in human cells. Moreover, cell viability in FK866-treated cells supplemented with extracellular NMN was strongly reduced in tumor cells, upon pharmacological inhibition or specific down-regulation of CD73. Thus, our study suggests that genetic or pharmacologic interventions interfering with CD73 activity may prove useful to increase cancer cell sensitivity to NAMPT inhibitors.

  10. Co-stimulation with bone morphogenetic protein-9 and FK506 induces remarkable osteoblastic differentiation in rat dedifferentiated fat cells.

    Science.gov (United States)

    Nakamura, Toshiaki; Shinohara, Yukiya; Momozaki, Sawako; Yoshimoto, Takehiko; Noguchi, Kazuyuki

    2013-10-18

    Dedifferentiated fat (DFAT) cells, which are isolated from mature adipocytes using the ceiling culture method, exhibit similar characteristics to mesenchymal stem cells, and possess adipogenic, osteogenic, chondrogenic, and myogenic potentials. Bone morphogenetic protein (BMP)-2 and -9, members of the transforming growth factor-β superfamily, exhibit the most potent osteogenic activity of this growth factor family. However, the effects of BMP-2 and BMP-9 on the osteogenic differentiation of DFAT remain unknown. Here, we examined the effects of BMP-2 and BMP-9 on osteoblastic differentiation of rat DFAT (rDFAT) cells in the presence or absence of FK506, an immunosuppressive agent. Co-stimulation with BMP-9 and FK506 induced gene expression of runx2, osterix, and bone sialoprotein, and ALP activity compared with BMP-9 alone, BMP-2 alone and BMP-2+FK506 in rDFAT cells. Furthermore, it caused mineralization of cultures and phosphorylation of smad1/5/8, compared with BMP-9 alone. The ALP activity induced by BMP-9+FK506 was not influenced by addition of noggin, a BMP antagonist. Our data suggest that the combination of BMP-9 and FK506 potently induces osteoblastic differentiation of rDFAT cells.

  11. The actions of cyclosporin A and FK506 suggest a novel step in the activation of T lymphocytes.

    Science.gov (United States)

    Mattila, P S; Ullman, K S; Fiering, S; Emmel, E A; McCutcheon, M; Crabtree, G R; Herzenberg, L A

    1990-01-01

    Cyclosporin A and FK506 are immunosuppressive compounds that have similar inhibitory effects on the expression of several lymphokines produced by T lymphocytes. Despite their similar effects the drugs bind to two different cytosolic protein, cyclophilin and FKBP respectively, which raises the possibility that they have different modes of action. Using constructs in which mRNA production controlled by a specific transcription factor could be readily measured we found that both cyclosporin A and FK506 completely inhibited transcription activated by NF-AT, NFIL2 A, NFIL2 B and partially inhibited transcription activated by NF kappa B. Cyclosporin A and FK506 inhibited only transcriptional activation that was dependent on Ca2+ mobilization. However, cyclosporin A and FK506 did not inhibit Ca2+ mobilization dependent expression of c-fos mRNA indicating that only a subset of signalling pathways regulated by Ca2+ is sensitive to these drugs. Furthermore, we did not observe any qualitative differences between the effect of cyclosporin A and FK506 on six different transcription factors which suggests that these drugs may interfere with the activity of a novel Ca2+ dependent step that regulates several transcription factors. Images Fig. 1. Fig. 3. Fig. 4. Fig. 6. Fig. 7. PMID:1702384

  12. FK Comae Berenices, King of Spin: The COCOA-PUFS Project

    Science.gov (United States)

    Ayres, Thomas R.; Kashyap, V.; Saar, S.; Huenemoerder, D.; Korhonen, H.; Drake, J. J.; Testa, P.; Cohen, O.; Garraffo, C.; Granzer, T.; Strassmeier, K.

    2016-03-01

    COCOA-PUFS is an energy-diverse, time-domain study of the ultra-fast spinning, heavily spotted, yellow giant FK Comae Berenices (FK Com: HD117555; G4 III). This single star is thought to be a recent binary merger, and is exceptionally active by measure of its intense ultraviolet (UV) and X-ray emissions, and proclivity to flare. COCOA-PUFS was carried out with the Hubble Space Telescope in the UV (1200-3000 Å), using mainly its high-performance Cosmic Origins Spectrograph, but also high precision Space Telescope Imaging Spectrograph; Chandra X-ray Observatory in the soft X-rays (0.5-10 keV), utilizing its High-Energy Transmission Grating Spectrometer; together with supporting photometry and spectropolarimetry in the visible from the ground. This is an introductory report on the project. FK Com displayed variability on a wide range of timescales over all wavelengths during the week-long main campaign, including a large X-ray flare; “super-rotational broadening” of the far-ultraviolet “hot lines” (e.g., Si iv 1393 Å 8 × 104 K) together with chromospheric Mg ii 2800 Å and C ii 1335 Å (1-3 × 104 K); large Doppler swings suggestive of bright regions alternately on advancing and retreating limbs of the star; and substantial redshifts of the epoch-average emission profiles. These behaviors paint a picture of a highly extended, dynamic, hot (˜10 MK) coronal magnetosphere around the star, threaded by cooler structures perhaps analogous to solar prominences and replenished continually by surface activity and flares. Suppression of angular momentum loss by the confining magnetosphere could temporarily postpone the inevitable stellar spindown, thereby lengthening this highly volatile stage of coronal evolution. COordinated Campaign of Observations and Analysis, Photosphere to Upper Atmosphere, of a Fast-rotating Star.

  13. Persistent C II absorption in the normal type Ia supernova 2002fk

    Energy Technology Data Exchange (ETDEWEB)

    Cartier, Régis; Zelaya, Paula [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hamuy, Mario; Maza, José; González, Luis; Huerta, Leonor [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Pignata, Giuliano [Departamento Ciencias Fisicas, Universidad Andres Bello, Av. República 252, Santiago (Chile); Förster, Francisco [Center for Mathematical Modelling, Universidad de Chile, Avenida Blanco Encalada 2120, Piso 7, Santiago (Chile); Folatelli, Gaston [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Phillips, Mark M.; Morrell, Nidia; Contreras, Carlos; Roth, Miguel; González, Sergio [Carnegie Institution of Washington, Las Campanas Observatory, Colina el Pino s/n, Casilla 601 (Chile); Krisciunas, Kevin; Suntzeff, Nicholas B. [Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843 (United States); Clocchiatti, Alejandro [Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago (Chile); Coppi, Paolo [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Koviak, Kathleen, E-mail: rcartier@das.uchile.cl [Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 911901 (United States)

    2014-07-01

    We present well-sampled UBVRIJHK photometry of SN 2002fk starting 12 days before maximum light through 122 days after peak brightness, along with a series of 15 optical spectra from –4 to +95 days since maximum. Our observations show the presence of C II lines in the early-time spectra of SN 2002fk, expanding at 11,000 km s{sup –1} and persisting until 8 days past maximum light with a velocity of ∼9000 km s{sup –1}. SN 2002fk is characterized by a small velocity gradient of v-dot {sub Si} {sub II}=26 km s{sup –1} day{sup –1}, possibly caused by an off-center explosion with the ignition region oriented toward the observer. The connection between the viewing angle of an off-center explosion and the presence of C II in the early-time spectrum suggests that the observation of C II could be also due to a viewing angle effect. Adopting the Cepheid distance to NGC 1309 we provide the first H {sub 0} value based on near-infrared (near-IR) measurements of a Type Ia supernova (SN) between 63.0 ± 0.8 (±3.4 systematic) and 66.7 ± 1.0 (±3.5 systematic) km s{sup –1} Mpc{sup –1}, depending on the absolute magnitude/decline rate relationship adopted. It appears that the near-IR yields somewhat lower (6%-9%) H {sub 0} values than the optical. It is essential to further examine this issue by (1) expanding the sample of high-quality near-IR light curves of SNe in the Hubble flow, and (2) increasing the number of nearby SNe with near-IR SN light curves and precise Cepheid distances, which affords the promise to deliver a more precise determination of H {sub 0}.

  14. FK COMAE BERENICES, KING OF SPIN: THE COCOA-PUFS PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Ayres, Thomas R. [Center for Astrophysics and Space Astronomy, 389 UCB, University of Colorado, Boulder, CO 80309 (United States); Kashyap, V.; Saar, S.; Drake, J. J.; Testa, P.; Cohen, O.; Garraffo, C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Huenemoerder, D. [Massachusetts Institute of Technology, Cambridge, MA (United States); Korhonen, H. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Piikkiö (Finland); Granzer, T.; Strassmeier, K., E-mail: Thomas.Ayres@Colorado.edu [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)

    2016-03-15

    COCOA-PUFS is an energy-diverse, time-domain study of the ultra-fast spinning, heavily spotted, yellow giant FK Comae Berenices (FK Com: HD117555; G4 III). This single star is thought to be a recent binary merger, and is exceptionally active by measure of its intense ultraviolet (UV) and X-ray emissions, and proclivity to flare. COCOA-PUFS was carried out with the Hubble Space Telescope in the UV (1200–3000 Å), using mainly its high-performance Cosmic Origins Spectrograph, but also high precision Space Telescope Imaging Spectrograph; Chandra X-ray Observatory in the soft X-rays (0.5–10 keV), utilizing its High-Energy Transmission Grating Spectrometer; together with supporting photometry and spectropolarimetry in the visible from the ground. This is an introductory report on the project. FK Com displayed variability on a wide range of timescales over all wavelengths during the week-long main campaign, including a large X-ray flare; “super-rotational broadening” of the far-ultraviolet “hot lines” (e.g., Si iv 1393 Å; 8 × 10{sup 4} K) together with chromospheric Mg ii 2800 Å and C ii 1335 Å (1–3 × 10{sup 4} K); large Doppler swings suggestive of bright regions alternately on advancing and retreating limbs of the star; and substantial redshifts of the epoch-average emission profiles. These behaviors paint a picture of a highly extended, dynamic, hot (∼10 MK) coronal magnetosphere around the star, threaded by cooler structures perhaps analogous to solar prominences and replenished continually by surface activity and flares. Suppression of angular momentum loss by the confining magnetosphere could temporarily postpone the inevitable stellar spindown, thereby lengthening this highly volatile stage of coronal evolution.

  15. Coronas implantosoportadas: ¿individualizar o ferulizar?

    Directory of Open Access Journals (Sweden)

    M Gómez Polo

    Full Text Available Existen diferentes formas de rehabilitación de coronas sobre implantes adyacentes en un tramo edéntulo. Las opciones que pueden encontrarse son la de restaurar con varias coronas unitarias, o bien unir esas coronas en una sola prótesis. Material y Método: Se llevó a cabo una búsqueda bibliográfica a través de bases de datos en revistas especializadas de Odontología. Resultados: En la bibliografía revisada se observa que existen defensores y detractores de cada una de las técnicas, basándose cada autor en distintos estudios y argumentos. Discusión: Se encontraron ventajas e inconvenientes en ambas opciones prostodóncicas, valorando en base a éstos cuándo utilizar cada una de las técnicas propuestas. Conclusiones: Cuando las condiciones son idóneas, se considera adecuada la restauración con coronas individuales; por otro lado cuando existan condiciones adversas (implantes cortos, hueso de mala calidad, carga inmediata o factores oclusales no adecuados, en las que el reparto de fuerzas pueda comprometer el pronóstico de la restauración, la ferulización será el tratamiento de elección.

  16. Positive and negative pulsed corona in argon

    NARCIS (Netherlands)

    Veldhuizen, E.M. van; Rutgers, W.R.; Ebert, U.

    2002-01-01

    Photographs are obtained of corona discharges in argon at atmospheric pressure using a high resolution, intensified CCD camera. Positive and negative polarity is applied at the curved electrode in a point-plane gap and a plane-plane gap with a protruding point. Branching is observed in the positive

  17. Computational insights into the suicide inhibition of Plasmodium falciparum Fk506-binding protein 35.

    Science.gov (United States)

    MacDonald, Corey A; Boyd, Russell J

    2015-08-15

    Malaria is a parasite affecting millions of people worldwide. With the risk of malarial resistance reaching catastrophic levels, novel methods into the inhibition of this disease need to be prioritized. The exploitation of active site differences between parasitic and human peptidyl-prolyl cis/trans isomerases can be used for suicide inhibition, effectively poisoning the parasite without affecting the patient. This method of inhibition was explored using Plasmodium falciparum and Homo sapiens Fk506-binding proteins as templates for quantum mechanics/molecular mechanics calculations. Modification of the natural substrate has shown suicide inhibition is a valid approach for novel anti-malarials with little risk for parasitic resistance.

  18. Rational design and asymmetric synthesis of potent and neurotrophic ligands for FK506-binding proteins (FKBPs).

    Science.gov (United States)

    Pomplun, Sebastian; Wang, Yansong; Kirschner, Alexander; Kozany, Christian; Bracher, Andreas; Hausch, Felix

    2015-01-01

    To create highly efficient inhibitors for FK506-binding proteins, a new asymmetric synthesis for pro-(S)-C(5) -branched [4.3.1] aza-amide bicycles was developed. The key step of the synthesis is an HF-driven N-acyliminium cyclization. Functionalization of the C(5)  moiety resulted in novel protein contacts with the psychiatric risk factor FKBP51, which led to a more than 280-fold enhancement in affinity. The most potent ligands facilitated the differentiation of N2a neuroblastoma cells with low nanomolar potency.

  19. Systematic Review and Metaanalysis of the Efficacy of FK506 in Experimental Stroke%FK506对实验性卒中疗效的系统评价和Meta分析

    Institute of Scientific and Technical Information of China (English)

    Malcolm R Macleod; Tori O'Collins; Laura L Horky; David W Howells; Geoffrey A Donnan; 段建钢; 张世洪

    2006-01-01

    FK506是治疗急性卒中的一种候选用药.决定一种药物是否可以用于临床试验,应当以全面的、无偏倚的动物实验数据的评估为依据,同时还应考虑到这些数据的局限性.这种评估不但应包括药物疗效,而且也应包括药效在体内的特征和局限性.本研究应用系统评价和Meta分析的方法对FK506在卒中动物模型中保护作用的证据进行评价.总共纳入了29个描述了实验步骤的研究,包括1 759只动物.结果显示,FK506疗效的点估计值(结局指标的改善)是31.3%[95%CI(0.272~0.354)].在采用氯胺酮麻醉和短暂性脑缺血的动物实验中,FK506的疗效更高,在使用大鼠,合并其他疾病的动物及仅以梗死面积为疗效指标的实验中,FK506疗效较低.已发表的实验研究质量均接近临床试验标准,但在高质量的研究中,FK506的疗效较低.FK506在实验性脑卒中的研究中,虽然显示出有明显的疗效,但是应注意由于研究质量和可能的发表偏倚等因素的影响,FK506的疗效可能被过高估计.

  20. Inhibition of NAMPT pathway by FK866 activates the function of p53 in HEK293T cells

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Basant Kumar, E-mail: thakur.basant@mh-hannover.de [Department of Pediatrics, Hematology and Oncology, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany); Department of Molecular Hematopoiesis, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany); Dittrich, Tino [Department of Pediatrics, Hematology and Oncology, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany); Department of Molecular Hematopoiesis, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany); Chandra, Prakash [Frankfurt University Medical School, Molecular Biology, Building 57, Theodor-Stern-Kai-7, 60590 Frankfurt (Germany); Becker, Annette [Department of Biology, Technical University of Darmstadt, 64287 Darmstadt (Germany); Lippka, Yannick [Department of Molecular Hematopoiesis, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany); Selvakumar, Divakarvel [Department of Molecular Hematopoiesis, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany); Rutgers, The State University of New Jersey, NJ 08901 (United States); Klusmann, Jan-Henning; Reinhardt, Dirk [Department of Pediatrics, Hematology and Oncology, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany); Welte, Karl, E-mail: Welte.Karl.H@mh-hannover.de [Department of Molecular Hematopoiesis, Hannover Medical School, Carl Neuberg Str-1, 30625 Hannover (Germany)

    2012-08-03

    Highlights: Black-Right-Pointing-Pointer In 293T cells, p53 is considered to be inactive due to its interaction with the large T-antigen. Black-Right-Pointing-Pointer Acetylation of p53 at lysine 382 is important for its functional activation. Black-Right-Pointing-Pointer First evidence to document the presence of a functional p53 in 293T cells. Black-Right-Pointing-Pointer Inhibition of NAMPT/SIRT pathway by FK866 in 293T cells increases the functional activity of p53. Black-Right-Pointing-Pointer This activation of p53 involves reversible acetylation of p53 at lysine 382. -- Abstract: Inactivation of p53 protein by endogenous and exogenous carcinogens is involved in the pathogenesis of different human malignancies. In cancer associated with SV-40 DNA tumor virus, p53 is considered to be non-functional mainly due to its interaction with the large T-antigen. Using the 293T cell line (HEK293 cells transformed with large T antigen) as a model, we provide evidence that p53 is one of the critical downstream targets involved in FK866-mediated killing of 293T cells. A reduced rate of apoptosis and an increased number of cells in S-phase was accompanied after knockdown of p53 in these cells. Inhibition of NAMPT by FK866, or inhibition of SIRT by nicotinamide decreased proliferation and triggered death of 293T cells involving the p53 acetylation pathway. Additionally, knockdown of p53 attenuated the effect of FK866 on cell proliferation, apoptosis, and cell cycle arrest. The data presented here shed light on two important facts: (1) that p53 in 293T cells is active in the presence of FK866, an inhibitor of NAMPT pathway; (2) the apoptosis induced by FK866 in 293T cells is associated with increased acetylation of p53 at Lys382, which is required for the functional activity of p53.

  1. Expression of FK506 binding protein 65 (FKBP65) is decreased in epithelial ovarian cancer cells compared to benign tumor cells and to ovarian epithelium

    DEFF Research Database (Denmark)

    Henriksen, Rudi; Sørensen, Flemming Brandt; Orntoft, Torben Falck;

    2011-01-01

    FK506 binding protein 65 (FKBP65) belongs to a group of proteins termed immunophilins that have a high binding affinity to immunosuppressant drugs as FK506 (tacrolimus) and rapamycin (sirolimus). Treatment of female premenopausal women with tacrolimus, which binds to FKBP65, has been reported...

  2. Study of FK Comae Berenices. I. Surface images for 1994 and 1995

    Science.gov (United States)

    Korhonen, H.; Berdyugina, S. V.; Hackman, T.; Duemmler, R.; Ilyin, I. V.; Tuominen, I.

    1999-06-01

    We present new surface images of FK Com for August 1994 and July 1995. For the 1995 images two different inversion methods, Tikhonov regularization and the Occamian approach, are used to check the dependence on the formal assumptions. The images are found to be very similar when the same local line profiles, models, stellar parameters and observations are used as inputs for both methods. The validity of the maps and their temperature scales are independently checked with photometric observations. The maps for both years show active regions of very similar substructures and latitudes. It seems that the same spot group has survived on the surface of FK Com for the 11 months between the observations; however, during that time it has moved about 0.2 in phase. The movement and evolution of the spot groups seem to cause the photometrically observed ``flip-flop'' phenomenon, which is noticed to be repeated with an average period of 6.5 years, similar to some RS CVn-stars. Based on the observations obtained at the Nordic Optical Telescope, Observatorio Roque de los Muchachos, La Palma, Canary Islands, Spain.

  3. FK Comae Berenices, King of Spin: The COCOA-PUFS Project

    CERN Document Server

    Ayres, Thomas R; Saar, S; Huenemoerder, D; Korhonen, H; Drake, J J; Testa, P; Cohen, O; Garraffo, C; Granzer, T; Strassmeier, K

    2016-01-01

    COCOA-PUFS is an energy-diverse, time-domain study of the ultra-fast spinning, heavily spotted, yellow giant FK Com (HD117555; G4 III). This single star is thought to be a recent binary merger, and is exceptionally active by measure of its intense ultraviolet and X-ray emissions, and proclivity to flare. COCOA-PUFS was carried out with Hubble Space Telescope in the UV (120-300 nm), using mainly its high-performance Cosmic Origins Spectrograph, but also high-precision Space Telescope Imaging Spectrograph; Chandra X-ray Observatory in the soft X-rays (0.5-10 keV), utilizing its High-Energy Transmission Grating Spectrometer; together with supporting photometry and spectropolarimetry in the visible from the ground. This is an introductory report on the project. FK Com displayed variability on a wide range of time scales, over all wavelengths, during the week-long main campaign, including a large X-ray flare; "super-rotational broadening" of the far-ultraviolet "hot-lines" (e.g., Si IV 139 nm (T~80,000 K) together...

  4. Helium corona-assisted air discharge

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Nan; Gao Lei; Ji Ailing; Cao Zexian [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-10-15

    Operation of atmospheric discharge of electronegative gases including air at low voltages yet without consuming any inert gas will enormously promote the application of non-thermal plasmas. By taking advantage of the low onset voltage for helium corona, air discharge was successfully launched at much reduced voltages with a needle-plate system partly contained in a helium-filled glass bulb--for a needle-plate distance of 12 mm, 1.0 kV suffices. Ultraviolet emission from helium corona facilitates the discharging of air, and the discharge current manifests distinct features such as relatively broad Trichel pulses in both half periods. This design allows safe and economic implementation of atmospheric discharge of electronegative gases, which will find a broad palette of applications in surface modification, plasma medicine and gas treatment, etc.

  5. Duality, Tangential Interpolation, and Toeplitz Corona Problems

    CERN Document Server

    Raghupathi, Mrinal

    2009-01-01

    In this paper we extend a method of Arveson and McCullough to prove a tangential interpolation theorem for subalgebras of $H^\\infty$. This tangential interpolation result implies a Toelitz corona theorem. In particular, it is shown that the set of matrix positivity conditions is indexed by cyclic subspaces, which is analogous to the results obtained for the ball and the polydisk algebra by Trent-Wick and Douglas-Sarkar.

  6. Miniature loops in the solar corona

    CERN Document Server

    Barczynski, Krzysztof; Savage, Sabrina L

    2016-01-01

    Magnetic loops filled with hot plasma are the main building blocks of the solar corona. Usually they have lengths of the order of the barometric scale height in the corona that is 50 Mm. Previously it has been suggested that miniature versions of hot loops exist. These would have lengths of only 1 Mm barely protruding from the chromosphere and spanning across just one granule in the photosphere. Such short loops are well established at transition region temperatures (0.1 MK), and we investigate if such miniature loops also exist at coronal temperatures (>1 MK). We used extreme UV imaging (EUV) observations from the High-resolution Coronal Imager (Hi-C) at an unprecedented spatial resolution of 0.3" to 0.4". Together with EUV imaging and magnetogram data from the Solar Dynamics Observatory (SDO) and X-Ray Telescope (XRT) data from Hinode we investigated the spatial, temporal and thermal evolution of small loop-like structures in the solar corona above a plage region close to an active region and compared this ...

  7. FK-DLR properties of a quantum multi-type Bose-gas with a repulsive interaction

    Energy Technology Data Exchange (ETDEWEB)

    Suhov, Y., E-mail: yms@statslab.cam.ac.uk [Statistical Laboratory, DPMMS, University of Cambridge (United Kingdom); Department of Statistics/IME, University of São Paulo (Brazil); IITP, RAS, Moscow (Russian Federation); Stuhl, I., E-mail: izabella@ime.usp.br [University of Debrecen (Hungary); IME, University of São Paulo (Brazil)

    2014-08-01

    The paper extends earlier results from Suhov and Kelbert [“FK-DLR states of a quantum Bose-gas with a hardcore interaction,” http://arxiv.org/abs/arXiv:1304.0782 ] and Suhov et al. [“Shift-invariance for FK-DLR states of a 2D quantum Bose-gas,” http://arxiv.org/abs/arXiv:1304.4177 ] about infinite-volume quantum bosonic states (FK-DLR states) to the case of multi-type particles with non-negative interactions. (An example is a quantum Widom–Rowlinson model.) Following the strategy from Suhov and Kelbert and Suhov et al., we establish that, for the values of fugacity zϵ(0, 1) and inverse temperature β > 0, finite-volume Gibbs states form a compact family in the thermodynamic limit. Next, in dimension two we show that any limit-point state (an FK-DLR state in the terminology adopted in Suhov and Kelbert and Suhov et al.) is translation-invariant.

  8. Calcineurin inhibition with FK506 ameliorates dendritic spine density deficits in plaque-bearing Alzheimer model mice.

    Science.gov (United States)

    Rozkalne, Anete; Hyman, Bradley T; Spires-Jones, Tara L

    2011-03-01

    Synapse loss is the strongest correlate of cognitive decline in Alzheimer's disease, and synapses are an attractive therapeutic target due to their plastic nature that allows for potential recovery with intervention. We have previously demonstrated in transgenic mice that form senile plaques that dendrites surrounding plaques become dystrophic and lose postsynaptic dendritic spines. Furthermore, we found strong evidence that plaque-associated dendritic changes are mediated by calcineurin, a calcium-dependent phosphatase involved in cell signaling, using in vitro models and genetically encoded inhibitors in mouse models. In this study, we pharmacologically inhibited calcineurin with FK506 treatment to test the hypothesis that calcineurin inhibition will allow recovery of plaque-associated synapse loss. We found that in plaque bearing transgenic mice, short term (1 week) FK506 treatment results in an amelioration of dendritic spine loss. We also observe an effect on spine morphology in wild-type mice with FK506 treatment. These data show that systemic FK506 administration, and hence calcineurin inhibition, may be neuroprotective for amyloid beta induced synaptic alterations.

  9. MRI in seven cases of tacrolimus (FK-506) encephalopathy: utility of FLAIR and diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, M. [Dept. of Radiology, Yamaguchi University School of Medicine, Ube (Japan); Dept. of Radiology, Hokkaido University School of Medicine, Sapporo (Japan); Terae, S.; Chu, B.C.; Kaneko, K.; Kamada, H.; Miyasaka, K. [Dept. of Radiology, Hokkaido University School of Medicine, Sapporo (Japan)

    2001-08-01

    We assessed the utility of fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted (DWI) images in investigation of tacrolimus (FK-506) encephalopathy, and to see whether we could predict its cause from clinical and imaging data. In seven patients with presumed FK-506 toxicity the areas involved on MRI were similar to those in cyclosporin A (CsA) toxicity. The abnormal signal was most evident on FLAIR in all cases. In three of four patients who underwent DWI, no diffusion abnormalities were detected; in the remaining patient, increased diffusion was seen in the deep white matter bilaterally on the apparent diffusion coefficient map, consistent with the findings on T2-weighted spin-echo and FLAIR images. Five of the six patients for whom we had clinical data showed sudden changes in electrolyte or fluid equilibrium due to diarrhoea, a polyuria or oliguria one day before or on the day of onset of the central nervous system disturbances. We speculate that FK-506 encephalopathy is triggered by the disturbance of the electrolyte and/or fluid equilibrium, given a certain serum level of FK-506. (orig.)

  10. Hubungan Kejadian Internet Addiction dengan Prestasi Belajar pada Mahasiswa FK Unand

    Directory of Open Access Journals (Sweden)

    Rizky Erizka

    2016-09-01

    Full Text Available AbstrakTeknologi internet berkembang sangat pesat dalam beberapa tahun terakhir dengan berbagai manfaat positif dan negatifnya. Internet addiction merupakan salah satu dampak negatif yang ditimbulkan. Dalam beberapa penelitian disebutkan pengaruh internet addiction terhadap beberapa aspek termasuk pendidikan. Tujuan penelitian ini adalah mengetahui angka kejadian internet addiction dan mempelajari hubungannya dengan prestasi belajar pada mahasiswa Fakultas Kedokteran Unand. Metode studi cross sectional dilakukan terhadap mahasiswa FK Unand angkatan 2011. Hasil penelitian diolah dengan menggunakan uji chi-square. Hasil penelitian menunjukkan kejadian internet addiction mempengaruhi prestasi belajar pada mahasiswa FK Unand. Sebanyak 1,1% subjek mengalami internet addiction berat, 34,4% sedang dan 37,7% ringan. Berdasarkan jenis kelamin perempuan lebih banyak mengalami internet addiction daripada laki laki karena  perempuan yang lebih banyak. Klasifikasi yang terbanyak adalah cyber-relationship dan metode paling banyak yang digunakan untuk mengakses internet adalah dengan menggunakan smartphone. Hasil lain yang didapatkan adalah kebutuhan dasar dan ibadah adalah kegiatan paling dominan yang dapat menghentikan responden dari mengakses internet. Disimpulkan bahwa kejadian internet addiction mempengaruhi prestasi belajar pada mahasiswa FK Unand.Kata kunci: cyber-relationship, internet, internet addiction, prestasi belajar AbstractThe internet technology grow very fast in recent years bringing many positive and negative effects. Internet addiction is one of the negative effect. Several research confirm some negative effect of internet addiction including  academic problem. The objective of this study was to know frequency and it’s relation with academic achievement in Medical Faculty of Andalas university’s students. This was a cross-sectional study on Medical Faculty of Andalas University’s students. The result were analyzed by chi

  11. Radio seismology of the outer solar corona

    Science.gov (United States)

    Zaqarashvili, Teimuraz; Melnik, Valentin; Brazhenko, Anatoliy; Panchenko, Mykhaylo; Konovalenko, Alexander; Dorovskyy, Vladimir; Rucker, Helmut

    2014-05-01

    Observed oscillations of coronal loops in extreme ultraviolet (EUV) lines have been successfully used to estimate plasma parameters in the inner corona ( 0.2R0). We used the large Ukrainian radio telescope URAN-2 to observe type IV radio bursts at the frequency range of 8-32 MHz during the time interval of 09:50-12:30 UT on April 14, 2011. The burst was connected to C2.3 flare, which occurred in AR 11190 during 09:38-09:49 UT. The dynamic spectrum of radio emission shows clear quasi-periodic variations in the emission intensity at almost all frequencies. Wavelet analysis at four different frequencies (29 MHz, 25 MHz, 22 MHz, and 14 MHz) shows the quasi-periodic variation of emission intensity with periods of ~ 34 min and ~ 23 min. The periodic variations can be explained by the first and second harmonics of vertical kink oscillation of transequatorial coronal loops, which were excited by the same flare. The apex of transequatorial loops may reach up to 1.2 R0 altitude. We derive and solve the dispersion relation of trapped magnetohydrodynamic (MHD) oscillations in a longitudinally inhomogeneous magnetic slab. The analysis shows that a thin (with width to length ratio of 0.1), dense (with the ratio of internal and external densities of ≥ 20) magnetic slab with weak longitudinal inhomogeneity may trap the observed oscillations. Seismologically estimated Alfvén speed inside the loop at the height of ~ 1 R0 is ~ 1000 km s-1. The magnetic field strength at this height is estimated as ~ 0.9 G. Extrapolation of magnetic field strength to the inner corona gives ~ 10 G at the height of 0.1 R0. Radio observations can be successfully used for the sounding of the outer solar corona, where EUV observations of coronal loops fail. Therefore, radio seismology of the outer solar corona is complementary to EUV seismology of the inner corona. The research leading to these results has received funding from the Austrian 'Fonds zur Förderung der wissenschaftlichen Forschung' under

  12. Monte Carlo simulation of electrical corona discharge in air

    Energy Technology Data Exchange (ETDEWEB)

    Settaouti, A.; Settaouti, L. [Electrotechnic Department, University of Sciences and Technology, P.O. Box 1505, El-M' naouar, Oran (Algeria)

    2011-01-15

    Electrical discharges play a key role in technologies; there are many industrial applications where the corona discharge is used. Air as insulator is probably the best compromise solution for many applications. All of this reflects on the great importance of the evaluation of the corona performance characteristics. Numerical simulation of the corona discharge helps to better understand the involved phenomena and optimize the corona devices. This paper is aimed at calculating the corona discharge in negative point-plane air gaps. To describe the non-equilibrium behavior of the electronic avalanches and to simulate the development of corona discharge the method of Monte Carlo has been used. This model provides the spatial-temporal local field and particles charged densities variations as well as the ionization front velocity. (author)

  13. Dynamic corona characteristics of water droplets on charged conductor surface

    Science.gov (United States)

    Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

    2017-03-01

    The formation of the Taylor cone of a water droplet on the surface of the conductor in a line-ground electrode system is captured using a high-speed camera, while the corona current is synchronously measured using a current measurement system. Repeated Taylor cone deformation is observed, yielding regular groupings of corona current pulses. The underlying mechanism of this deformation is studied and the correlation between corona discharge characteristics and cone deformation is investigated. Depending on the applied voltage and rate of water supply, the Taylor cone may be stable or unstable and has a significant influence on the characteristics of the corona currents. If the rate of water supply is large enough, the Taylor cone tends to be unstable and generates corona-current pulses of numerous induced current pulses with low amplitudes. In consequence, this difference suggests that large rainfall results in simultaneously lower radio interference and higher corona loss.

  14. Safety and long-term effect of the probiotic FK-23 in patients with hepatitis C virus infection

    Science.gov (United States)

    OO, Khin May; LWIN, Aye Aye; KYAW, Yi Yi; TUN, Win Maw; FUKADA, Kazutake; GOSHIMA, Akiko; SHIMADA, Takashi; OKADA, Shigeru

    2016-01-01

    A clinical trial was conducted on 39 adult HCV-positive subjects to determine the safety and long-term effect of the probiotic FK-23 (heat-treated Enterococcus faecalis strain FK-23). Asymptomatic anti-HCV positive adults who fulfilled the selection criteria and gave voluntary consent were recruited from attendees of the Hepatitis Carrier Clinic, Department of Medical Research (Lower Myanmar). Each subject was given 2,700 mg of FK-23 per day by oral route. Blood samples were taken at enrollment and every 3 months and tested for alanine aminotransferase (ALT) and aspartate transaminase (AST). Viral load, urea, total protein, hemoglobin and platelet count were determined every 6 months. Among the subjects, 23 completed 36 months, 31 completed 24 months, 35 completed 12 months and 37 completed 6 months of probiotic therapy. Significant decreases in mean ALT levels were observed at 3 months (34. 9 ± 15.1 IU/l) as compared with the initial level (64.8 ± 17.5 IU/l) and persisted up to 36 months (43.7 ± 25.2 IU/l). Decrease of AST was detected after 9 months (46.2 ± 21.7 IU/l) of probiotic therapy as compared with the initial level (64.3 ± 28.7 IU/l). FK-23 was safe based on the stable levels of biochemical and hematological parameters and the absence of untoward side effects. The FK-23 preparation was well tolerated and accepted by the subjects. PMID:27508113

  15. Mycophenolate mofetil and FK506 have different effects on kidney allograft fibrosis in rats that underwent chronic allograft nephropathy

    Directory of Open Access Journals (Sweden)

    Luo Lei

    2012-07-01

    Full Text Available Abstract Background Tacrolimus (FK506 is associated with renal fibrosis in long-term use. Mycophenolatemofetil (MMF can also inhibit or attenuate the progression of renal fibrosis. This study aimed to determine the different effects of FK506 and MMF on fibrosis-associated genes in the kidney in rats that underwent chronic allograft nephropathy (CAN. Methods Fisher (F344 kidneys were orthotopically transplanted into Lewis rat recipients. All recipients were given Cyclosporin A (CsA 10 mg/kg-1.d-1 × 10 day and were then randomly divided into three oral treatment groups (n = 9 in each group: (1 the vehicle group was given vehicle orally; (2 the FK506 group was given 0.15 mg/kg-1.d-1 FK506; and (3 the MMF group was given 20 mg/kg-1.d-1 MMF. At 4, 8, and 12 weeks post-transplantation, serum creatinine (SCr, collagen deposition, Connective tissue growth factor (CTGF, alpha smooth muscle actin (α-SMA and E-cadherin expressions were determined and hematoxylin-eosin (HE and Periodic acid-Schiff (PAS stains were performed. Results Renal function progressively deteriorated and showed typical CAN morphology in the vehicle and FK506 groups, while SCr and inflammatory infiltration (Banff score showed a significant decrease in the MMF group after 8 weeks post-transplantation compared with those in the other groups (p α-SMA in the MMF group were significantly reduced, and the down-regulated expression of E-cadherin was abated (p  Conclusions MMF showed favorable effects on renal interstitial fibrosis, thus efficiently retarding the progression of CAN.

  16. FK506-loaded chitosan conduit promotes the regeneration of injured sciatic nerves in the rat through the upregulation of brain-derived neurotrophic factor and TrkB.

    Science.gov (United States)

    Zhao, Jia; Zheng, Xifu; Fu, Chongyang; Qu, Wei; Wei, Guoqiang; Zhang, Weiguo

    2014-09-15

    FK506 has been shown to exert neurotrophic and neuroprotective effects, but its long-term application for nerve regeneration is limited. This study evaluated the potential application of a novel FK506-loaded chitosan conduit for peripheral nerve repair, and explored the underlying mechanism. A sciatic nerve injury model was created in male Wistar rats, which were then randomly divided into three treatment groups (n=40, each): chitosan-only, chitosan+FK506 injection, and FK506-loaded chitosan. We found significant recovery of normal morphology of sciatic nerves and higher density of myelinated nerve fibers in rats treated with FK506-loaded chitosan. Similarly, the total number of myelinated nerve fibers, myelin sheath thickness, and axon diameters were significantly higher in this group compared with the others, and the compound muscle action potentials and motor nerve conduction velocity values of sciatic nerves were significantly higher. BDNF and TrkB levels in motor neurons were highest in rats treated with FK506-loaded chitosan. In conclusion, FK506-loaded chitosan promoted peripheral nerve repair and regeneration in a rat model of sciatic nerve injury. These effects are correlated with increased BDNF and TrkB expression in motor neurons.

  17. The Sun's Corona Observed by the Skylab Mission

    Science.gov (United States)

    1970-01-01

    The Sun's corona stretches far beyond the dense, irner corona seen in x-rays and ultraviolet light, and beyond the limits of what we normally see in the dark sky of a total solar eclipse. Its farthest reaches are delineated by tapered streamers that stretch into interplanetary space, extending the domain of our nearest star much farther than its visible disk. We see the outer corona briefly at total eclipses of the Sun, where it appears white and delicate against the starry background of a temporarily darkened, daytime sky. Even then, Earth's intervening atmosphere is bright enough to limit our view of the outer corona. At Skylab's orbital altitude, where almost no air was left and where the sky was starkly black, the outer corona was at last clearly seen. In the thousands of coronal portraits made by Skylab, in which the corona was observed more extensively than in all the centuries of humanity's interest in the Sun, the corona was constantly altering its form, ever adjusting to the shifting magnetic fields from the Sun's surface that so obviously gave it its distinctive shape. Skylab's coronagraph observations coupled with x-ray pictures of the inner corona helped establish the origin of the corona's varied forms and the important connection between coronal holes and high-speed streams in the solar wind.

  18. Design of the UHVDC Corona Cage in China

    Institute of Scientific and Technical Information of China (English)

    GUO Jian; LU Jiayu; ZHANG Wenliang

    2013-01-01

    For the purpose of testing and analysing the corona characteristics of UHVDC bundle conductors,UHVDC corona cage would be built in China.Corona cage is one of the indispensable equipments for conductor corona performance researches.Tests of conductor cotona characteristics in corona cages can overcome the shortages of those with test lines.The dimensions of several corona cages constructed overseas were introduced in this paper.Based on foreign experiences and the requirement of State Grid Corporation of China,the UHVDC corona cage was designed as double-cage,double-layer,three-seetions,and catenary shape with the size of 70 m×22 m× 13 m.The corona loss measurement system,radio interference measuring system,and the audible noise measuring system are also detailed,including the measurement theory,connection with the cage,the parameters and the designing basis.The UHVDC corona cage has been put into service.It now undergoes a large amount of audible noise and radio frequency interference tests.

  19. The HDAC inhibitor FK228 enhances adenoviral transgene expression by a transduction-independent mechanism but does not increase adenovirus replication.

    Science.gov (United States)

    Danielsson, Angelika; Dzojic, Helena; Rashkova, Victoria; Cheng, Wing-Shing; Essand, Magnus

    2011-02-17

    The histone deacetylase inhibitor FK228 has previously been shown to enhance adenoviral transgene expression when cells are pre-incubated with the drug. Upregulation of the coxsackie adenovirus receptor (CAR), leading to increased viral transduction, has been proposed as the main mechanism. In the present study, we found that the highest increase in transgene expression was achieved when non-toxic concentrations of FK228 were added immediately after transduction, demonstrating that the main effect by which FK228 enhances transgene expression is transduction-independent. FK228 had positive effects both on Ad5 and Ad5/f35 vectors with a variety of transgenes and promoters, indicating that FK228 works mainly by increasing transgene expression at the transcriptional level. In some cases, the effects were dramatic, as demonstrated by an increase in CD40L expression by FK228 from 0.3% to 62% when the murine prostate cancer cell line TRAMP-C2 was transduced with Ad[CD40L]. One unexpected finding was that FK228 decreased the transgene expression of an adenoviral vector with the prostate cell-specific PPT promoter in the human prostate adenocarcinoma cell lines LNCaP and PC-346C. This is probably a consequence of alteration of the adenocarcinoma cell lines towards a neuroendocrine differentiation after FK228 treatment. The observations in this study indicate that FK228 enhances adenoviral therapy by a transduction-independent mechanism. Furthermore, since histone deacetylase inhibitors may affect the differentiation of cells, it is important to keep in mind that the activity and specificity of tissue- and tumor-specific promoters may also be affected.

  20. The HDAC inhibitor FK228 enhances adenoviral transgene expression by a transduction-independent mechanism but does not increase adenovirus replication.

    Directory of Open Access Journals (Sweden)

    Angelika Danielsson

    Full Text Available The histone deacetylase inhibitor FK228 has previously been shown to enhance adenoviral transgene expression when cells are pre-incubated with the drug. Upregulation of the coxsackie adenovirus receptor (CAR, leading to increased viral transduction, has been proposed as the main mechanism. In the present study, we found that the highest increase in transgene expression was achieved when non-toxic concentrations of FK228 were added immediately after transduction, demonstrating that the main effect by which FK228 enhances transgene expression is transduction-independent. FK228 had positive effects both on Ad5 and Ad5/f35 vectors with a variety of transgenes and promoters, indicating that FK228 works mainly by increasing transgene expression at the transcriptional level. In some cases, the effects were dramatic, as demonstrated by an increase in CD40L expression by FK228 from 0.3% to 62% when the murine prostate cancer cell line TRAMP-C2 was transduced with Ad[CD40L]. One unexpected finding was that FK228 decreased the transgene expression of an adenoviral vector with the prostate cell-specific PPT promoter in the human prostate adenocarcinoma cell lines LNCaP and PC-346C. This is probably a consequence of alteration of the adenocarcinoma cell lines towards a neuroendocrine differentiation after FK228 treatment. The observations in this study indicate that FK228 enhances adenoviral therapy by a transduction-independent mechanism. Furthermore, since histone deacetylase inhibitors may affect the differentiation of cells, it is important to keep in mind that the activity and specificity of tissue- and tumor-specific promoters may also be affected.

  1. Reconnection Processes in the Chromosphere and Corona

    Science.gov (United States)

    Shibata, Kazunari

    2012-07-01

    Magnetic reconnection is a fundamental key physical process in magnetized plasmas. Recent space solar observations revealed that magnetic reconnection is ubiquitous in the solar chromospheres and corona. Especially recent Hinode observations has found various types of tiny chromospheric jets, such as chromospheric anemone jets (Shibata et al. 2007), penumbral microjets (Katsukawa et al. 2007), light bridge jets from sunspot umbra (Shimizu et al. 2009), etc. It was also found that the corona is full of tiny X-ray jets (Cirtain et al. 2007). Often they are seen as helical spinning jets (Shimojo et al. 2007, Patsourakos et al. 2008, Pariat et al. 2009, Filippov et al. 2009, Kamio et al. 2010) with Alfvenic waves (Nishizuka et al. 2008, Liu et al. 2009) and there are increasing evidence of magnetic reconnection in these tiny jets. We can now say that as spatial resolution of observations become better and better, smaller and smaller flares and jets have been discovered, which implies that the magnetized solar atmosphere consist of fractal structure and dynamics, i.e., fractal reconnection. Bursty radio and hard X-ray emissions from flares also suggest the fractal reconnection and associated particle acceleration. Since magnetohydrodynamics (MHD) does not contain any characteristic length and time scale, it is natural that MHD structure, dynamics, and reconnection, tend to become fractal in ideal MHD plasmas with large magnetic Reynolds number such as in the solar atmosphere. We would discuss recent observations and theories related to fractal reconnection in the chromospheres and corona, and discuss possible implication to chromospheric and coronal heating.

  2. Plasma Heating of Titan's Exobase and Corona

    Science.gov (United States)

    Karn, M.; Smith, H. T.; Tucker, O. J.; Johnson, R. E.; de La Haye, V.; Waite, J. H.; Young, D. A.

    2007-12-01

    Cassini data have shown that the dominant heating process for Titan's atmospheric corona and exobase region is as yet uncertain (DeLaHaye et al. 2007). We have speculated that the incident plasma, both the slowed and deflected ambient ions and the pick-up ions, may be responsible for all or a significant fraction of the non-thermal component of Titan's corona (De La Haye et al. 2007). Our earlier models of the net incident plasma heating (Michael et al. 2004; 2005) fall short in describing the coronal structure seen by INMS on Ta, Tb and T5. Since heating of the corona and exobase affects atmospheric escape, it is critical for describing the evolution of Titan's atmosphere (Johnson 2004). Here we describe an empirical approach to this problem. INMS data and the preliminary CAPS flux data clearly indicate, not surprisingly, that the heating is spatially non-uniform and is variable, but there is as yet no correlation with the plasma flow models. Therefore, we haev analyzed INMS data for the atmospheric structure near the exobase for a large number of Cassini passes through the exobase region and we have analyzed certain CAPS data for the plasma flow near the exobase. The goal is to develop a model for the spatial variations in the plasma heating near the exobase with the goal of improving our knowledge of atmospheric escape. De La Haye, V.. et al., JGR 112, A07309, doi:10.1029/2006JA012222, 2007 Johnson, R.E. ApJ 609, L99, 2004 Michael, M., and R. E. Johnson. PSS 53, 1510, 2005. Michael, M., et al. Icarus, 175, 263, 2005.

  3. Hydrogen Production from Methanol Using Corona Discharges

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Hydrogen production at room temperature from liquid methanol has been conductedusing corona discharge. The content of water in methanol solution has a significant effect on thisproduction. When water concentration increases from 1.0 % to 16.7 %, the methanol conversionrate changes from 0.196 to 0.284 mol/h. An important finding in this investigation is theformation of ethylene glycol as a major by-product. The yield of ethylene glycol is ranged from0.0045 to 0.0075 mol/h based on the water content.

  4. Fluorine in R Coronae Borealis Stars

    CERN Document Server

    Pandey, Gajendra; Rao, N Kameswara

    2007-01-01

    Neutral fluorine (F I) lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is enriched in some RCBs by factors of 800 to 8000 relative to its likely initial abundance. The overabundances of fluorine are evidence for the synthesis of fluorine. These results are discussed in the light of the scenario that RCBs are formed by accretion of an He white dwarf by a C-O white dwarf. Sakurai's object (V4334 Sgr), a final He-shell flash product, shows no detectable F I lines.

  5. Heating mechanisms of the solar corona

    Science.gov (United States)

    Sakurai, Takashi

    2017-02-01

    The solar corona is a tenuous outer atmosphere of the Sun. Its million-degree temperature was discovered spectroscopically in the 1940s, but its origin has been debated since then without complete convergence. Currently there are two classes of models; the wave theory and the microflare/nanoflare theory. Both models have merits and disadvantages, but the essential issues are nearly pinned down. Recent revival of the wave theory is one of the many contributions from Japanese solar observing satellite Hinode launched in 2006.

  6. Effect of 0.025% FK-506 eyedrops on botulinum toxin B-induced mouse dry eye.

    Science.gov (United States)

    Lin, Bin-wu; Chen, Mei-zhu; Fan, Shu-xian; Chuck, Roy S; Zhou, Shi-you

    2014-12-09

    To investigate the effect of FK-506 eye drops on Botulinum toxin B (BTX-B)-induced mouse dry eye. Forty-five CBA/J mice were followed up for 4 weeks after treatment with 0.025% FK-506, vehicle or 0.9% saline eye drops 3 days after intralacrimal glands injection with 20 milliunits BTX-B. Tear production, corneal fluorescein staining, the mRNA, and protein expression of cytokines were measured. The activation of nuclear factor-κB (NF-κB) was detected by Western blotting. The infiltration of inflammatory cells was examined by immunohistochemistry. After treated with FK-506 eye drops, aqueous tear production in the mice began to recover at week 1, and then increased to the levels of pre-BTX-B injection at week 4 (2.21 ± 0.43 vs. 2.52 ± 0.71 mm, t = 0.84, P > 0.05). The severity of corneal epithelial defects was alleviated at week 2 and further improved at week 4 when compared with those in the vehicle- and saline-treated groups. The gene expression of IL-1β and TNF-α in the FK-506 and vehicle-treated groups were 47.01% and 45.56%, 85.91% and 115.83% of that in the saline-treated group in the ocular surface, while in the lacrimal glands 49.16% and 67.60%, 94.91% and 95.77% of that in the saline-treated group, respectively. The ratio of phosphorylated IκB-α to total IκB-α in the keratoconjunctival tissues was lower in the FK-506-treated group than in the vehicle- and saline-treated groups (both P < 0.05). No inflammatory cells were detected in all groups. Topical application of FK-506 can inhibit NF-κB activation and related inflammatory response and alleviate the signs of dry eye. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  7. Formulation and Characterization of LX-17-2 from new FK 800 binder and WA, ATK, and BAE TATBs

    Energy Technology Data Exchange (ETDEWEB)

    DePiero, S C; Hoffman, D M

    2007-08-03

    Currently LLNL has no Kel-F 800 or wet-aminated TATB reserves for formulation. Although both materials are soon to be commercially available, their synthesis processes have changed and the explosive must be re-evaluated. In 2000 3M phased out the uses of perfluorooctanoyl (C8) derivatives due to environmental persistence and bioaccumulation issues. A C8 derivative was used as an emulsifier for making Kel F-800. In 2001 Kel F-800 was scheduled to be discontinued and the last Kel F-800 run was made in early 2002. LANL ordered 2M$ worth of Kel-F 800 for reserves and Pantex purchased several hundred pounds to satisfy mock needs. After four years, 3M has decided to introduce a Kel-F 800-like polymer based on a new emulsifier using the same chlorotrifluoroethylene and vinylidene fluoride monomers and emulsion polymerization process. They have produced 3 batches and claim the 'new' FK-800 is indistinguishable from the 'old' Kel-F 800 in any of their testing parameters. In June-July 2006 3M scaled up a batch of about 800 pounds and have test quantities available. We have samples of the new FK-800 for evaluation. Neither wet nor dry-aminated TATB has been synthesized in the US in any significant quantity since about 1985 and significant quantities of LX-17-1 has not been formulated since about 1990. Over the last few years as part of a DOD MANTECH, ATK Thiokol and BAE Holston Army Ammunition Plant (HAAP) have produced moderate quantities of TATB ({approx}5 kg batches) with plans to scale up for DOD applications. Thiokol TATB is polycrystalline with an average particle size of about 40 m (similar to WA TATB) but HAAP TATB is only 5-6 {micro}m (similar to ultrafine). We have obtained small quantities of these materials for evaluation. The project (1) compares new FK-800 with old Kel-F 800 and FK-800 lots currently available at LLNL, (2) compares and characterizes new TATB with old TATB, (3) formulates new FK-800 with wet-aminated TATB and new TATBs in

  8. The Corona Limit of Penrose Tilings Is a Regular Decagon

    OpenAIRE

    Akiyama, Shigeki; Imai, Katsunobu

    2016-01-01

    Part 2: Regular Papers; International audience; We define and study the corona limit of a tiling, by investigating the signal propagations on cellular automata (CA) on tilings employing the simple growth CA. In particular, the corona limit of Penrose tilings is the regular decagon.

  9. The nanoparticle biomolecule corona: lessons learned - challenge accepted?

    Science.gov (United States)

    Docter, D; Westmeier, D; Markiewicz, M; Stolte, S; Knauer, S K; Stauber, R H

    2015-10-07

    Besides the wide use of engineered nanomaterials (NMs) in technical products, their applications are not only increasing in biotechnology and biomedicine, but also in the environmental field. While the physico-chemical properties and behaviour of NMs can be characterized accurately under idealized conditions, this is no longer the case in complex physiological or natural environments. Herein, proteins and other biomolecules rapidly bind to NMs, forming a protein/biomolecule corona that critically affects the NMs' (patho)biological and technical identities. As the corona impacts the in vitro and/or in vivo NM applications in humans and ecosystems, a mechanistic understanding of its relevance and of the biophysical forces regulating corona formation is mandatory. Based on recent insights, we here critically review and present an updated concept of corona formation and evolution. We comment on how corona signatures may be linked to effects at the nano-bio interface in physiological and environmental systems. In order to comprehensively analyse corona profiles and to mechanistically understand the coronas' biological/ecological impact, we present a tiered multidisciplinary approach. To stimulate progress in this field, we introduce the potential impact of the corona for NM-microbiome-(human)host interactions and the novel concept of 'nanologicals', i.e., the nanomaterial-specific targeting of molecular machines. We conclude by discussing the relevant challenges that still need to be resolved in this field.

  10. Protein corona – from molecular adsorption to physiological complexity

    Directory of Open Access Journals (Sweden)

    Lennart Treuel

    2015-03-01

    Full Text Available In biological environments, nanoparticles are enshrouded by a layer of biomolecules, predominantly proteins, mediating its subsequent interactions with cells. Detecting this protein corona, understanding its formation with regards to nanoparticle (NP and protein properties, and elucidating its biological implications were central aims of bio-related nano-research throughout the past years. Here, we discuss the mechanistic parameters that are involved in the protein corona formation and the consequences of this corona formation for both, the particle, and the protein. We review consequences of corona formation for colloidal stability and discuss the role of functional groups and NP surface functionalities in shaping NP–protein interactions. We also elaborate the recent advances demonstrating the strong involvement of Coulomb-type interactions between NPs and charged patches on the protein surface. Moreover, we discuss novel aspects related to the complexity of the protein corona forming under physiological conditions in full serum. Specifically, we address the relation between particle size and corona composition and the latest findings that help to shed light on temporal evolution of the full serum corona for the first time. Finally, we discuss the most recent advances regarding the molecular-scale mechanistic role of the protein corona in cellular uptake of NPs.

  11. Personalized protein coronas : a "key" factor at the nanobiointerface

    NARCIS (Netherlands)

    Hajipour, Mohammad J.; Laurent, Sophie; Aghaie, Afsaneh; Rezaee, Farhad; Mahmoudi, Morteza

    2014-01-01

    It is now well known that the primary interactions of biological entities (e. g., tissues and cells) with nano-particles (NPs) are strongly influenced by the protein composition of the "corona" (i. e., the NP surface attached proteins). The composition of the corona strongly depends on the protein s

  12. Protein corona - from molecular adsorption to physiological complexity.

    Science.gov (United States)

    Treuel, Lennart; Docter, Dominic; Maskos, Michael; Stauber, Roland H

    2015-01-01

    In biological environments, nanoparticles are enshrouded by a layer of biomolecules, predominantly proteins, mediating its subsequent interactions with cells. Detecting this protein corona, understanding its formation with regards to nanoparticle (NP) and protein properties, and elucidating its biological implications were central aims of bio-related nano-research throughout the past years. Here, we discuss the mechanistic parameters that are involved in the protein corona formation and the consequences of this corona formation for both, the particle, and the protein. We review consequences of corona formation for colloidal stability and discuss the role of functional groups and NP surface functionalities in shaping NP-protein interactions. We also elaborate the recent advances demonstrating the strong involvement of Coulomb-type interactions between NPs and charged patches on the protein surface. Moreover, we discuss novel aspects related to the complexity of the protein corona forming under physiological conditions in full serum. Specifically, we address the relation between particle size and corona composition and the latest findings that help to shed light on temporal evolution of the full serum corona for the first time. Finally, we discuss the most recent advances regarding the molecular-scale mechanistic role of the protein corona in cellular uptake of NPs.

  13. Time-Dependent Tomographic Reconstruction of the Solar Corona

    CERN Document Server

    Vibert, Didier; Lamy, Philippe; Frazin, Richard A; Wojak, Julien

    2016-01-01

    Solar rotational tomography (SRT) applied to white-light coronal images observed at multiple aspect angles has been the preferred approach for determining the three-dimensional (3D) electron density structure of the solar corona. However, it is seriously hampered by the restrictive assumption that the corona is time-invariant which introduces significant errors in the reconstruction. We first explore several methods to mitigate the temporal variation of the corona by decoupling the "fast-varying" inner corona from the "slow-moving" outer corona using multiple masking (either by juxtaposition or recursive combination) and radial weighting. Weighting with a radial exponential profile provides some improvement over a classical reconstruction but only beyond 3 Rsun. We next consider a full time-dependent tomographic reconstruction involving spatio-temporal regularization and further introduce a co-rotating regularization aimed at preventing concentration of reconstructed density in the plane of the sky. Crucial t...

  14. Constraints on Lithospheric Rheology from Observations of Coronae on Venus

    Science.gov (United States)

    O'Rourke, Joseph G.; Smrekar, Suzanne; Moresi, Louis N.

    2016-10-01

    Coronae are enigmatic, quasi-circular features found in myriad geological environments. They are primarily distinguished as rings of concentric fractures superimposed on various topographic profiles with at least small-scale volcanism. Mantle plumes may produce coronae with interior rises, whereas coronae with central depressions are often attributed to downwellings like Rayleigh-Taylor instabilities. For almost three decades, modelers have attempted to reproduce the topographic and gravity profiles measured at coronae. Until recently, few studies also considered tectonic deformation and melt production. In particular, "Type 2" coronae have complete topographic rims but arcs of fractures extending less than 180°, signifying both brittle and ductile deformation. Only a narrow range of rheological parameters like temperature and volatile content may be compatible with these observations. Ultimately, identifying how lithospheric properties differ between Earth and Venus is critical to understanding what factors permit plate tectonics on rocky, Earth-sized planets.Here we present a hierarchical approach to study the formation of coronae. First, we discuss an observational survey enabled by a new digital elevation model derived from stereo topography for ~20% of the surface of Venus, which offers an order-of-magnitude improvement over the horizontal resolution (10 to 20 kilometers) of altimetry data from NASA's Magellan mission. Next, we search this new dataset for signs of lithospheric flexure around small coronae. Simple, thin-elastic plate models were fit to topographic profiles of larger coronae in previous studies, but data resolution impeded efforts to apply this method to the entire coronae population. Finally, we show simulations of the formation of coronae using Underworld II, an open-source code adaptable to a variety of geodynamical problems. We benchmark our code using models of pure Rayleigh-Taylor instabilities and then investigate the influence of

  15. Prevalensi Ansietas Menjelang Ujian Tulis pada Mahasiswa Kedokteran Fk Unand Tahap Akademik

    Directory of Open Access Journals (Sweden)

    Tomas Apriady

    2016-09-01

    Full Text Available AbstrakAnsietas atau kecemasan adalah perasaan difus, yang sangat tidak menyenangkan dan tidak menentu tentang sesuatu yang akan terjadi. Ujian tulis merupakan salah satu bentuk evaluasi terhadap kemampuan mahasiswa. Hampir semua mahasiswa pendidikan dokter Fakultas Kedokteran Universitas Andalas (FK Unand yang tidak lulus dalam blok yang sedang mereka jalani diakibatkan karena tidak lulus di ujian tulis. Hal ini menyebabkan mahasiswa cenderung merasa cemas ketika akan menghadapi ujian tulis. Tujuan penelitian ini adalah menentukan prevalensi ansietas pada mahasiswa kedokteran menjelang ujiantulis. Penelitian ini bersifat deskriptif terhadap  266 orang yang dipilih secara stratified random sampling. Instrumen yang digunakan adalah kuesioner HARS (Hamilton Anxiety Rating Scale. Hasil yang didapatkan disajikan dalam bentuk tabel distribusi frekuensi. Hasil penelitian ini menunjukkan bahwa prevalensi ansietas pada mahasiswa kedokteran FK Unand tahap akademik menjelang ujian tulis sebesar 46,99%, ansietas ringan prevalensinya sebesar 30,45%, ansietas sedang sebesar 12,78% dan ansietas berat sebesar 3,76%. Pada tingkat angkatan, maka yang terbanyak adalah Angkatan 2012 yaitu sebanyak 57,78%. Berdasarkan jenis kelaminnya, maka terbanyak pada perempuan yaitu 50,81%. Berdasarkan tempat tinggalnya, prevalensi ansietas yang terbanyak adalah yang tinggal bersama orang tua, yaitu 55,17%.Kata kunci: ansietas, ujian tulis, mahasiswa kedokteran AbstractAnxiety is a feeling diffuse, very unpleasant and uncertain about something that will happen. Written test is one form of evaluation of student ability. Almost all medical students of Andalas University who do not pass the blocks which they were living caused by not passed on the written test. This causes students tend to feel anxious when going to face a written test. The objective of this study was to determine the prevalence of anxiety in medical students before the written test. This was a descriptive

  16. An orally active adenosine A1 receptor antagonist, FK838, increases renal excretion and maintains glomerular filtration rate in furosemide-resistant rats

    Science.gov (United States)

    Schnackenberg, Christine G; Merz, Emily; Brooks, David P

    2003-01-01

    Loop and thiazide diuretics are common therapeutic agents for the treatment of sodium retention and oedema. However, resistance to diuretics and decreases in renal function can develop during diuretic therapy. Adenosine causes renal vasoconstriction, sodium reabsorption, and participates in the tubuloglomerular feedback mechanism for the regulation of glomerular filtration rate.We tested the hypothesis that the selective adenosine A1 receptor antagonist FK838 is orally active and causes diuresis and natriuresis, but maintains glomerular filtration rate in normal rats or in rats with furosemide resistance.In normal male Sprague – Dawley rats, FK838 dose-dependently increased urine flow and sodium and chloride excretion while sparing potassium. In combination with furosemide, FK838 enhanced the diuretic and natriuretic actions of furosemide to the same extent as hydrochlorothiazide and did not increase the potassium loss in normal rats. In furosemide-resistant rats, FK838 increased urine flow and electrolyte excretion to a greater extent than hydrochlorothiazide. In addition, hydrochlorothiazide significantly decreased glomerular filtration rate, whereas FK838 maintained glomerular filtration rate in furosemide-resistant rats.This study shows that the adenosine A1 receptor antagonist FK838 is orally active and causes potent diuresis and natriuresis and maintains glomerular filtration rate in normal or furosemide-resistant rats. Adenosine A1 receptor antagonists may be novel therapeutics for the treatment of oedema in normal or otherwise diuretic-resistant patients. PMID:12922924

  17. Marketingový mix FK Pardubice a návrhy na jeho zlepšení

    OpenAIRE

    Šejvl, Martin

    2016-01-01

    Title: Marketing mix of FK Pardubice and proposals for its improvement. Targets: Analysis of various marketing instruments that form the marketing mix sports club. Determine the views of fans for marketing the club and then suggest ways to improve the quality of marketing mix, which would lead to higher customer satisfaction and attendance of matches. Methods: Analysis of literature in the field of sports marketing, implementation and evaluation of the questionnaire, informal interviews, part...

  18. R Coronae Australis: A Cosmic Watercolour

    Science.gov (United States)

    2010-06-01

    This magnificent view of the region around the star R Coronae Australis was created from images taken with the Wide Field Imager (WFI) at ESO's La Silla Observatory in Chile. R Coronae Australis lies at the heart of a nearby star-forming region and is surrounded by a delicate bluish reflection nebula embedded in a huge dust cloud. The image reveals surprising new details in this dramatic area of sky. The star R Coronae Australis lies in one of the nearest and most spectacular star-forming regions. This portrait was taken by the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. The image is a combination of twelve separate pictures taken through red, green and blue filters. This image shows a section of sky that spans roughly the width of the full Moon. This is equivalent to about four light-years at the distance of the nebula, which is located some 420 light-years away in the small constellation of Corona Australis (the Southern Crown). The complex is named after the star R Coronae Australis, which lies at the centre of the image. It is one of several stars in this region that belong to the class of very young stars that vary in brightness and are still surrounded by the clouds of gas and dust from which they formed. The intense radiation given off by these hot young stars interacts with the gas surrounding them and is either reflected or re-emitted at a different wavelength. These complex processes, determined by the physics of the interstellar medium and the properties of the stars, are responsible for the magnificent colours of nebulae. The light blue nebulosity seen in this picture is mostly due to the reflection of starlight off small dust particles. The young stars in the R Coronae Australis complex are similar in mass to the Sun and do not emit enough ultraviolet light to ionise a substantial fraction of the surrounding hydrogen. This means that the cloud does not glow with the characteristic red colour seen in

  19. Immunosuppressive macrolides of the type FK 506: a novel class of topical agents for treatment of skin diseases?

    Science.gov (United States)

    Meingassner, J G; Stütz, A

    1992-06-01

    The immunosuppressive macrolide antibiotics FK 506 and rapamycin were tested for topical activity in experimental allergic contact dermatitis of farm pigs. This species was used because pig skin, in comparison to rodent skin, resembles human skin more closely. For comparison, cyclosporine A (CyA), which is orally but not topically active in patients with skin disease, dexamethasone, and clobetasol propionate were used. Treatment was performed twice, 30 min and 6 h after elicitation of challenge reaction. Topical application of 0.4 to 0.04% FK 506 caused a pronounced inhibition of inflammatory skin reactions of hypersensitivity to dinitrofluorobenzene. The treatment response was similar to the activity of 0.13% clobetasole. Dexamethasone (1.2%) was less active than clobetasol. In contrast, rapamycin and CyA were inactive at concentrations of 1.2 and 10%, respectively. Because the pig data on corticosteroids and cyclosporine A are in agreement with clinical findings, these studies indicate that immunosuppressive macrolides of the type FK 506 may be useful drugs for the topical treatment of human skin diseases that respond to local corticosteroids and oral treatment with cyclosporine A.

  20. Effect of FK506 on Expression of Hepatocyte Growth Factor in Murine Spinal Cord Following Peripheral Nerve Injury

    Institute of Scientific and Technical Information of China (English)

    Feng PAN; Anmin CHEN; Fengjing GUO; Chenliang ZHU; Fenghua TAO

    2008-01-01

    This study is to investigate the effect of FK506 on expression of hepatocyte growth factor (HGF) in rats' spinal cord following peripheral nerve injury and to elucidate the mechanisms for neuroprotective property of FKS06. Fifty male rats were randomly divided into normal group, injury group and treatment group. Models of peripheral nerve injury were established by bilateral transection of sciatic nerve 0.5 cm distal to piriform muscle. Then the treatment group received subcutaneons injection of FK506 (1 mg/kg) at the back of neck, while the injury group was given 0.9% saline. The L4-6 spinal cords were harvested at various time points after the surgery. Western blotting and immunofluorescent staining were used to detect the level and position of HGF in spinal cord. Lm munofluorescent staining showed that HGF-positive neurons were located in anterior horn, interme- diate zone and posterior horn of gray matter in normal spinal cord. Western blotting revealed that there was no significant difference in the expressions of HGF between the injury group and the normal group, while the expression of HGF was significantly higher in the treatment group than in the injury group 7 and 14 days after surgery. It is suggested that peripheral nerve injury does not result in up-regulation of the expression of HGF in spinal cord, while FK506 may induce high expression of endogenous HGF after injury thereby protecting neurons and promoting axonal outgrowth.

  1. Inhibition of Human Immunodeficiency Virus and Growth of Infected T Cells by the Immunosuppressive Drugs Cyclosporin A and FK 506

    Science.gov (United States)

    Karpas, Abraham; Lowdell, Mark; Jacobson, S. Kim; Hill, Fergal

    1992-09-01

    The effects of the immunosuppressive drugs cyclosporin A and FK 506 were studied on cells chronically infected with human immunodeficiency virus type 1 (HIV-1) as well as on uninfected and newly infected cells. When cells chronically infected with HIV-1 or with HIV-2 were cocultivated with uninfected cells in the presence of cyclosporin A or FK 506 there was a delay in the formation of syncytia and of cytopathic effects. This inhibitory effect was not due to decreased membrane expression of CD4. In addition, there was an ≈100-fold reduction in the yield of infectious HIV-1 when the infected cells were grown in the presence of these drugs, a finding consistent with other evidence of decreased HIV expression. Both drugs were found to inhibit the growth of chronically infected cells at concentrations that did not inhibit the growth of the uninfected cells. These results, demonstrating that cyclosporin A and FK 506 interfere with HIV production and selectively inhibit the growth of infected cells, suggest that they may be useful in the treatment of this infection and indicate further cellular targets for antiviral agents.

  2. Study of FK Comae Berenices: VII. Correlating photospheric and chromospheric activity

    CERN Document Server

    Vida, K; Ilyin, I V; Oláh, K; Andersen, M I; Hackman, T

    2015-01-01

    We study the connection between the chromospheric and photospheric behaviour of the active late-type star FK Comae. We use spot temperature modelling, light curve inversion based on narrow- and wide-band photometric measurements, Halpha observations from 1997-2010, and Doppler maps from 2004-2010 to compare the behaviour of chromospheric and photospheric features. Investigating low-resolution Halpha spectra we find that the changes in the chromosphere seem to happen mainly on a time scale longer than a few hours, but shorter variations were also observed. According to the Halpha measurements prominences are often found in the chromosphere that reach to more than a stellar radius and are stable for weeks, and which seem to be often, but not every time connected with dark photospheric spots. The rotational modulation of the Halpha emission seems to typically be anticorrelated with the light curve, but we did not find convincing evidence of a clear connection in the long-term trends of the Halpha emission and th...

  3. Synergistic Antitumor Effect of Doxorubicin and Tacrolimus (FK506 on Hepatocellular Carcinoma Cell Lines

    Directory of Open Access Journals (Sweden)

    Francesca Capone

    2014-01-01

    Full Text Available Hepatocellular carcinoma is the fifth most common cancer worldwide and shows a complex clinical course, poor response to pharmacological treatment, and a severe prognosis. Thus, the aim of this study was to investigate whether tacrolimus (FK506 has synergistic antitumor effects with doxorubicin on two human hepatocellular carcinoma cell lines, Huh7 and HepG2. Cell viability was analyzed by Sulforhodamine B assay and synergic effect was evaluated by the software CalcuSyn. Cell apoptosis was evaluated using Annexin V and Dead Cell assay. Apoptosis-related protein PARP-1 cleaved and autophagy-related protein expressions (Beclin-1 and LC3B were measured by western blotting analysis. Cytokines concentration in cellular supernatants after treatments was studied by Bio-Plex assay. Interestingly the formulation with doxorubicin and tacrolimus induced higher cytotoxicity level on tumor cells than single treatment. Moreover, our results showed that the mechanisms involved were (i a strong cell apoptosis induction, (ii contemporaneous decrease of autophagy activation, understood as prosurvival process, and (iii downregulation of proinflammatory cytokines. In conclusion, future studies could relate to the doxorubicin/tacrolimus combination effects in mice models bearing HCC in order to see if this formulation could be useful in HCC treatment.

  4. Charging of moving surfaces by corona discharges sustained in air

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Chieh, E-mail: junchwan@umich.edu; Kushner, Mark J., E-mail: mjkush@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109-2122 (United States); Zhang, Daihua, E-mail: dhzhang@tju.edu.cn [Tianjin University, Tianjin (China); Leoni, Napoleon, E-mail: napoleon.j.leoni@hp.com; Birecki, Henryk, E-mail: henryk.birecki@hp.com; Gila, Omer, E-mail: omer-gila@hp.com [Hewlett-Packard Research Labs, Palo Alto, California 94304 (United States)

    2014-07-28

    Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.

  5. Charging of moving surfaces by corona discharges sustained in air

    Science.gov (United States)

    Wang, Jun-Chieh; Zhang, Daihua; Leoni, Napoleon; Birecki, Henryk; Gila, Omer; Kushner, Mark J.

    2014-07-01

    Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.

  6. Space matters: meristem expansion triggers corona formation in Passiflora.

    Science.gov (United States)

    Claßen-Bockhoff, Regine; Meyer, Charlotte

    2016-02-01

    Flower meristems differ from vegetative meristems in various aspects. One characteristic is the capacity for ongoing meristem expansion providing space for new structures. Here, corona formation in four species of Passiflora is investigated to understand the spatio-temporal conditions of its formation and to clarify homology of the corona elements. One bird-pollinated species with a single-rowed tubular corona (Passiflora tulae) and three insect-pollinated species with three (P. standleyi Killip), four (P. foetida L. 'Sanctae Martae') and six (P. foetida L. var. hispida) ray-shaped corona rows are chosen as representative examples for the study. Flower development is documented by scanning electron microscopy. Meristem expansion is reconstructed by morphometric data and correlated with the sequential corona element formation. In all species, corona formation starts late in ontogeny after all floral organs have been initiated. It is closely correlated with meristem expansion. The rows appear with increasing space in centripetal or convergent sequence. Based on the concept of fractionation, space induces primordia formation which is a self-regulating process filling the space completely. Correspondingly, the corona is interpreted as a structure of its own, originating from the receptacle. Considering the principle capacity of flower meristems to generate novel structures widens the view and allows new interpretations in combination with molecular, phylogenetic and morphogenetic data. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Understanding the Kinetics of Protein-Nanoparticle Corona Formation.

    Science.gov (United States)

    Vilanova, Oriol; Mittag, Judith J; Kelly, Philip M; Milani, Silvia; Dawson, Kenneth A; Rädler, Joachim O; Franzese, Giancarlo

    2016-12-27

    When a pristine nanoparticle (NP) encounters a biological fluid, biomolecules spontaneously form adsorption layers around the NP, called "protein corona". The corona composition depends on the time-dependent environmental conditions and determines the NP's fate within living organisms. Understanding how the corona evolves is fundamental in nanotoxicology as well as medical applications. However, the process of corona formation is challenging due to the large number of molecules involved and to the large span of relevant time scales ranging from 100 μs, hard to probe in experiments, to hours, out of reach of all-atoms simulations. Here we combine experiments, simulations, and theory to study (i) the corona kinetics (over 10(-3)-10(3) s) and (ii) its final composition for silica NPs in a model plasma made of three blood proteins (human serum albumin, transferrin, and fibrinogen). When computer simulations are calibrated by experimental protein-NP binding affinities measured in single-protein solutions, the theoretical model correctly reproduces competitive protein replacement as proven by independent experiments. When we change the order of administration of the three proteins, we observe a memory effect in the final corona composition that we can explain within our model. Our combined experimental and computational approach is a step toward the development of systematic prediction and control of protein-NP corona composition based on a hierarchy of equilibrium protein binding constants.

  8. Kinetics of the formation of a protein corona around nanoparticles.

    Science.gov (United States)

    Zhdanov, Vladimir P; Cho, Nam-Joon

    2016-12-01

    Interaction of metal or oxide nanoparticles (NPs) with biological soft matter is one of the central phenomena in basic and applied biology-oriented nanoscience. Often, this interaction includes adsorption of suspended proteins on the NP surface, resulting in the formation of the protein corona around NPs. Structurally, the corona contains a "hard" monolayer shell directly contacting a NP and a more distant weakly associated "soft" shell. Chemically, the corona is typically composed of a mixture of distinct proteins. The corresponding experimental and theoretical studies have already clarified many aspects of the corona formation. The process is, however, complex, and its understanding is still incomplete. Herein, we present a kinetic mean-field model of the formation of the "hard" corona with emphasis on the role of (i) protein-diffusion limitations and (ii) interplay between competitive adsorption of distinct proteins and irreversible reconfiguration of their native structure. The former factor is demonstrated to be significant only in the very beginning of the corona formation. The latter factor is predicted to be more important. It may determine the composition of the corona on the time scales comparable or longer than a few hours.

  9. High Energy Particles in the Solar Corona

    CERN Document Server

    Widom, A; Larsen, L

    2008-01-01

    Collective Ampere law interactions producing magnetic flux tubes piercing through sunspots into and then out of the solar corona allow for low energy nuclear reactions in a steady state and high energy particle reactions if a magnetic flux tube explodes in a violent event such as a solar flare. Filamentous flux tubes themselves are vortices of Ampere currents circulating around in a tornado fashion in a roughly cylindrical geometry. The magnetic field lines are parallel to and largely confined within the core of the vortex. The vortices may thereby be viewed as long current carrying coils surrounding magnetic flux and subject to inductive Faraday and Ampere laws. These laws set the energy scales of (i) low energy solar nuclear reactions which may regularly occur and (ii) high energy electro-weak interactions which occur when magnetic flux coils explode into violent episodic events such as solar flares or coronal mass ejections.

  10. Nanoflares and Heating of the Solar Corona

    Indian Academy of Sciences (India)

    U. Narain; K. Pandey

    2006-06-01

    Coronal heating by nanoflares is presented by using observational, analytical, numerical simulation and statistical results. Numerical simulations show the formation of numerous current sheets if the magnetic field is sheared and bipoles have unequal pole strengths. This fact supports the generation of nanoflares and heating by them. The occurrence frequency of transients such as flares, nano/microflares, on the Sun exhibits a power-law distribution with exponent α varying between 1.4 and 3.3. For nanoflares heating must be greater than 2. It is likely that the nanoflare heating can be reproduced by dissipating Alfv´en waves. Only observations from future space missions such as Solar-B, to be launched in 2006, can shed further light on whether Alfvén waves or nanoflares, heat the solar corona.

  11. Nanoflares and Heating of the Solar Corona

    Science.gov (United States)

    Narain, U.; Pandey, K.

    2006-09-01

    Coronal heating by nanoflares is presented by using observational, analytical, numerical simulation and statistical results. Numerical simulations show the formation of numerous current sheets if the magnetic field is sheared and bipoles have unequal pole strengths. This fact supports the generation of nanoflares and heating by them. The occurrence frequency of transients such as flares, nano/microflares, on the Sun exhibits a power-law distribution with exponent α varying between 1.4 and 3.3. For nanoflares heating α must be greater than 2. It is likely that the nanoflare heating can be reproduced by dissipating Alfvén waves. Only observations from future space missions such as Solar-B, to be launched in 2006, can shed further light on whether Alfvén waves or nanoflares, heat the solar corona

  12. Coronae of Stars with Supersolar Elemental Abundances

    Science.gov (United States)

    Peretz, Uria; Behar, Ehud; Drake, Stephen A.

    2015-01-01

    Coronal elemental abundances are known to deviate from the photospheric values of their parent star, with the degree of deviation depending on the first ionization potential (FIP). This study focuses on the coronal composition of stars with supersolar photospheric abundances. We present the coronal abundances of six such stars: 11 LMi, iota Hor, HR 7291, tau Boo, and alpha Cen A and B. These stars all have high-statistics X-ray spectra, three of which are presented for the first time. The abundances we measured were obtained using the line-resolved spectra of the Reflection Grating Spectrometer (RGS) in conjunction with the higher throughput EPIC-pn camera spectra onboard the XMM-Newton observatory. A collisionally ionized plasma model with two or three temperature components is found to represent the spectra well. All elements are found to be consistently depleted in the coronae compared to their respective photospheres. For 11 LMi and tau Boo no FIP effect is present, while iota Hor, HR 7291, and alpha Cen A and B show a clear FIP trend. These conclusions hold whether the comparison is made with solar abundances or the individual stellar abundances. Unlike the solar corona, where low-FIP elements are enriched, in these stars the FIP effect is consistently due to a depletion of high-FIP elements with respect to actual photospheric abundances. A comparison with solar (instead of stellar) abundances yields the same fractionation trend as on the Sun. In both cases, a similar FIP bias is inferred, but different fractionation mechanisms need to be invoked.

  13. Laboratory studies of corona emissions from air terminals

    Science.gov (United States)

    D'Alessandro, F.; Berger, G.

    1999-11-01

    This paper presents some of the results obtained from a systematic series of laboratory investigations into the corona emission characteristics of air terminals. Two particular aspects are considered, namely the effect on corona emission of changing the distance between the tip of the air terminal and the overhead energized electrode, and the relationship between the two fundamental corona parameters (`amplitude coefficient' and onset electric field) and the height of the air terminal above a ground plane. The implications of the results for lightning protection designs are discussed.

  14. Transition region lineshifts and nanoflare heating of the corona.

    Science.gov (United States)

    Hansteen, V. H.

    After briefly reviewing previous data and new observations taken by the SUMER instrument aboard the SOHO spacecraft the author pursues the interpretation that the observed pervasive transition region line shifts are caused by MHD waves propagating along the magnetic field lines down from the corona towards the chromosphere. He argues that a likely source of such coronally generated MHD waves are the episodic magnetic reconection events that are believed to heat the corona. He also presents an alternate method of observation based on densitive sensitive line pairs that may give further evidence of the processes heating the corona.

  15. The TESIS experiment on the CORONAS-PHOTON spacecraft

    Science.gov (United States)

    Kuzin, S. V.; Zhitnik, I. A.; Shestov, S. V.; Bogachev, S. A.; Bugaenko, O. I.; Ignat'ev, A. P.; Pertsov, A. A.; Ulyanov, A. S.; Reva, A. A.; Slemzin, V. A.; Sukhodrev, N. K.; Ivanov, Yu. S.; Goncharov, L. A.; Mitrofanov, A. V.; Popov, S. G.; Shergina, T. A.; Solov'ev, V. A.; Oparin, S. N.; Zykov, A. M.

    2011-04-01

    On February 26, 2009, the first data was obtained in the TESIS experiment on the research of the solar corona using imaging spectroscopy. The TESIS is a part of the scientific equipment of the CORONAS-PHO-TON spacecraft and is designed for imaging the solar corona in soft X-ray and extreme ultraviolet regions of the spectrum with high spatial, spectral, and temporal resolutions at altitudes from the transition region to three solar radii. The article describes the main characteristics of the instrumentation, management features, and operation modes.

  16. The effect of atmospheric corona treatment on AA1050 aluminium

    DEFF Research Database (Denmark)

    Jariyaboon, Manthana; Møller, Per; Dunin-Borkowski, Rafal E.

    2010-01-01

    The effect of atmospheric corona discharge on AM 050 aluminium surface was investigated using electrochemical polarization, SEM-EDX, FIB-SEM. and XPS. The corona treatment was performed with varying time (1, 5, and 15 min) in atmospheric air. A 200 nm oxide layer was generated on AA1050 after...... the 15 min air corona treatment. A significant reduction in anodic and cathodic reactivities was observed starting from 1 min exposure, which further decreased with prolonged exposure (15 min) and after delayed testing (after 30 days). The reduction in surface reactivity is due to the formation...

  17. Studying the corona product of graphs under some graph invariants

    Directory of Open Access Journals (Sweden)

    M. Tavakoli

    2014-09-01

    Full Text Available The corona product $Gcirc H$ of two graphs $G$ and $H$ is obtained by taking one copy of $G$ and $|V(G|$ copies of $H$; and by joining each vertex of the $i$-th copy of $H$ to the $i$-th vertex of $G$, where $1 leq i leq |V(G|$. In this paper, exact formulas for the eccentric distance sum and the edge revised Szeged indices of the corona product of graphs are presented. We also study the conditions under which the corona product of graphs produces a median graph.

  18. Statistical characteristic in time-domain of direct current corona-generated audible noise from conductor in corona cage

    Science.gov (United States)

    Li, Xuebao; Cui, Xiang; Lu, Tiebing; Ma, Wenzuo; Bian, Xingming; Wang, Donglai; Hiziroglu, Huseyin

    2016-03-01

    The corona-generated audible noise (AN) has become one of decisive factors in the design of high voltage direct current (HVDC) transmission lines. The AN from transmission lines can be attributed to sound pressure pulses which are generated by the multiple corona sources formed on the conductor, i.e., transmission lines. In this paper, a detailed time-domain characteristics of the sound pressure pulses, which are generated by the DC corona discharges formed over the surfaces of a stranded conductors, are investigated systematically in a laboratory settings using a corona cage structure. The amplitude of sound pressure pulse and its time intervals are extracted by observing a direct correlation between corona current pulses and corona-generated sound pressure pulses. Based on the statistical characteristics, a stochastic model is presented for simulating the sound pressure pulses due to DC corona discharges occurring on conductors. The proposed stochastic model is validated by comparing the calculated and measured A-weighted sound pressure level (SPL). The proposed model is then used to analyze the influence of the pulse amplitudes and pulse rate on the SPL. Furthermore, a mathematical relationship is found between the SPL and conductor diameter, electric field, and radial distance.

  19. Statistical characteristic in time-domain of direct current corona-generated audible noise from conductor in corona cage

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuebao, E-mail: lxb08357x@ncepu.edu.cn; Cui, Xiang, E-mail: x.cui@ncepu.edu.cn; Ma, Wenzuo; Bian, Xingming; Wang, Donglai [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China); Lu, Tiebing, E-mail: tiebinglu@ncepu.edu.cn [Beijing Key Laboratory of High Voltage and EMC, North China Electric Power University, Beijing 102206 (China); Hiziroglu, Huseyin [Department of Electrical and Computer Engineering, Kettering University, Flint, Michigan 48504 (United States)

    2016-03-15

    The corona-generated audible noise (AN) has become one of decisive factors in the design of high voltage direct current (HVDC) transmission lines. The AN from transmission lines can be attributed to sound pressure pulses which are generated by the multiple corona sources formed on the conductor, i.e., transmission lines. In this paper, a detailed time-domain characteristics of the sound pressure pulses, which are generated by the DC corona discharges formed over the surfaces of a stranded conductors, are investigated systematically in a laboratory settings using a corona cage structure. The amplitude of sound pressure pulse and its time intervals are extracted by observing a direct correlation between corona current pulses and corona-generated sound pressure pulses. Based on the statistical characteristics, a stochastic model is presented for simulating the sound pressure pulses due to DC corona discharges occurring on conductors. The proposed stochastic model is validated by comparing the calculated and measured A-weighted sound pressure level (SPL). The proposed model is then used to analyze the influence of the pulse amplitudes and pulse rate on the SPL. Furthermore, a mathematical relationship is found between the SPL and conductor diameter, electric field, and radial distance.

  20. Inhibition of Calcineurin A by FK506 Suppresses Seizures and Reduces the Expression of GluN2B in Membrane Fraction.

    Science.gov (United States)

    Wen, Yuetao; Fu, Pengfei; Wu, Kunlun; Si, Kaichuang; Xie, Yanfeng; Dan, Wei; Zhan, Yan; Shi, Quanhong

    2017-08-01

    FK506, a calcineurin inhibitor, shows neuroprotective effects and has been associated with neurodegenerative diseases. Calcineurin A (CaNA), a catalytic subunit of calcineurin, mediates the dephosphorylation of various proteins. N-methyl-D-aspartate receptor (GluN) is closely related to epileptogenesis, and various phosphorylation sites of GluN2B, a regulatory subunit of the GluN complex, have different functions. Thus, we hypothesized that one of the potential anti-epileptic mechanisms of FK506 is mediated by its ability to promote the phosphorylation of GluN2B and reduce the expression of GluN2B in membrane fraction by down-regulating CaNA. CaNA expression was increased in the cortex of patients with temporal lobe epilepsy and pentylenetetrazol (PTZ)-induced epileptic models. CaNA was shown to be expressed in neurons using immunofluorescence staining. According to our behavioral observations, epileptic rats exhibited less severe seizures and were less sensitive to PTZ after a systemic injection of FK506. The levels of phosphorylated GluN2B were decreased in epileptic rats but increased after the FK506 treatment. Moreover, there was no difference in the total GluN2B levels before and after FK506 treatment. However, the expression of GluN2B in membrane fraction was suppressed after FK506 treatment. Based on these results, FK506 may reduce the severity and frequency of seizures by reducing the expression of GluN2B in membrane fraction.

  1. Direct observation of silver nanoparticle-ubiquitin corona formation

    CERN Document Server

    Ding, Feng; Choudhary, Poonam; Chen, Ran; Brown, Jared M; Ke, Pu Chun

    2012-01-01

    Upon entering physiological environments, nanoparticles readily assume the form of a nanoparticle-protein corona that dictates their biological identity. Understanding the structure and dynamics of nanoparticle-protein corona is essential for predicting the fate, transport, and toxicity of nanomaterials in living systems and for enabling the vast applications of nanomedicine. We combined multiscale molecular dynamics simulations and complementary experiments to characterize the silver nanoparticle-ubiquitin corona formation. Specifically, ubiquitins competed with citrates for the nanoparticle surface and bound to the particle in a specific manner. Under a high protein/nanoparticle stoichiometry, ubiquitions formed a multi-layer corona on the particle surface. The binding exhibited an unusual stretched-exponential behavior, suggesting a rich kinetics originated from protein-protein, protein-citrate, and protein-nanoparticle interactions. Furthermore, the binding destabilized the {\\alpha}-helices while increasi...

  2. Cyclical Variation of the Quiet Corona and Coronal Holes

    Indian Academy of Sciences (India)

    Takashi Sakurai

    2000-09-01

    Recent advances in the understanding of the quiet corona and coronal holes are reviewed. The review is based on long-term accumulation of data from eclipse observations, coronagraph observations, helium 10830 Å spectroheliograms, and X-ray observations.

  3. Degree distance and Gutman index of corona product of graphs

    Directory of Open Access Journals (Sweden)

    V. Sheeba Agnes

    2015-09-01

    Full Text Available In this paper, the degree distance and the Gutman index of the corona product of two graphs are determined. Using the results obtained, the exact degree distance and Gutman index of certain classes of graphs are computed.

  4. Decomposition characteristics of toluene by a corona radical shower system

    Institute of Scientific and Technical Information of China (English)

    WU Zu-liang; GAO Xiang; LUO Zhong-yang; NI Ming-jiang; CEN Ke-fa

    2004-01-01

    Non-thermal plasma technologies offer an innovative approach to decomposing various volatile organic compounds(VOCs). The decomposition of toluene from simulated flue gas was investigated using a pipe electrode with nozzles for the generation of free radicals. Corona characteristics and decomposition of toluene were investigated experimentally. In addition, the decomposition mechanism of toluene was explored in view of reaction rate. The experimental results showed that the humidity of additional gas has an important effect on corona characteristics and modes and stable streamer corona can be generated through optimizing flow rate and humidity of additional gas. Applied voltage, concentration of toluene, humidity of toluene and resident time are some important factors affecting decomposition efficiency. Under optimizing conditions, the decomposition efficiency of toluene can reach 80%. These results can give a conclusion that the corona radical shower technology is feasible and effective on the removal of toluene in the flue gas.

  5. Protein bio-corona: critical issue in immune nanotoxicology.

    Science.gov (United States)

    Neagu, Monica; Piperigkou, Zoi; Karamanou, Konstantina; Engin, Ayse Basak; Docea, Anca Oana; Constantin, Carolina; Negrei, Carolina; Nikitovic, Dragana; Tsatsakis, Aristidis

    2017-03-01

    With the expansion of the nanomedicine field, the knowledge focusing on the behavior of nanoparticles in the biological milieu has rapidly escalated. Upon introduction to a complex biological system, nanomaterials dynamically interact with all the encountered biomolecules and form the protein "bio-corona." The decoration with these surface biomolecules endows nanoparticles with new properties. The present review will address updates of the protein bio-corona characteristics as influenced by nanoparticle's physicochemical properties and by the particularities of the encountered biological milieu. Undeniably, bio-corona generation influences the efficacy of the nanodrug and guides the actions of innate and adaptive immunity. Exploiting the dynamic process of protein bio-corona development in combination with the new engineered horizons of drugs linked to nanoparticles could lead to innovative functional nanotherapies. Therefore, bio-medical nanotechnologies should focus on the interactions of nanoparticles with the immune system for both safety and efficacy reasons.

  6. Hubungan Kualitas Tidur dengan Prestasi Akademik Mahasiswa Program Studi Pendidikan Dokter Angkatan 2010 FK Universitas Andalas

    Directory of Open Access Journals (Sweden)

    Hanafi Nilifda

    2016-01-01

    Full Text Available AbstrakKualitas tidur seseorang dikatakan baik apabila tidak menunjukkan berbagai tanda kekurangan tidur dan tidak mengalami masalah dalam tidurnya. Gangguan tidur banyak ditemui dikalangan dewasa muda terutama mahasiswa yang nantinya bisa menyebabkan berkurangnya konsentrasi belajar dan gangguan kesehatan. Hal ini bisa menyebabkan tidak tercapainya prestasi akademik secara optimal karena proses belajar menjadi terganggu. Tujuan penelitian ini adalah untuk menentukan hubungan kualitas tidur dengan prestasi akademik mahasiswa pendidikan dokter angkatan 2010 FK Unand. Penelitian ini menggunakan metode analitik dengan rancangan cross sectional. Total responden sebanyak 177 orang yang dipilih dengan teknik random sampling. Data kualitas tidur diambil dengan menggunakan indeks kualitas tidur Pittsburgh (PSQI dan prestasi akademik dari nilai ujian blok 4.2. Pada akhir penelitian dilakukan uji statistik chi square untuk mengetahui hubungan kedua variabel. Hasil penelitian menunjukkan bahwa sebanyak 51 mahasiswa (65% memiliki kualitas tidur dan prestasi akademik yang baik, 27 mahasiswa (35% memiliki kualitas tidur yang baik dengan prestasi akademik yang kurang baik, 43 mahasiswa (43% memiliki kualitas tidur yang buruk dengan prestasi akademik yang baik, dan 56 mahasiswa (57% memiliki kualitas tidur yang buruk dan prestasi akademik yang kurang baik. Berdasarkan uji chi square didapatkan nilai p=0,004 (p<0,05. Penelitian ini menyimpulkan terdapat hubungan antara kualitas tidur dengan prestasi akademik mahasiswa pendidikan dokter angkatan 2010FK Unand.Kata kunci: kualitas tidur, prestasi akademik, mahasiswa kedokteran AbstractThe good quality of sleep is there is no any disturbance in their sleep. The condition of sleep disorders commonly found among young adults, especially college students who can later cause a reduction in the concentration of learning and health problems. This can lead to failure to achieve optimal academic achievement because

  7. Time-dependent tomographic reconstruction of the solar corona

    Science.gov (United States)

    Vibert, D.; Peillon, C.; Lamy, P.; Frazin, R. A.; Wojak, J.

    2016-10-01

    Solar rotational tomography (SRT) applied to white-light coronal images observed at multiple aspect angles has been the preferred approach for determining the three-dimensional (3D) electron density structure of the solar corona. However, it is seriously hampered by the restrictive assumption that the corona is time-invariant which introduces significant errors in the reconstruction. We first explore several methods to mitigate the temporal variation of the corona by decoupling the "fast-varying" inner corona from the "slow-moving" outer corona using multiple masking (either by juxtaposition or recursive combination) and radial weighting. Weighting with a radial exponential profile provides some improvement over a classical reconstruction but only beyond ≈ 3R⊙. We next consider a full time-dependent tomographic reconstruction involving spatio-temporal regularization and further introduce a co-rotating regularization aimed at preventing concentration of reconstructed density in the plane of the sky. Crucial to testing our procedure and properly tuning the regularization parameters is the introduction of a time-dependent MHD model of the corona based on observed magnetograms to build a time-series of synthetic images of the corona. Our procedure, which successfully reproduces the time-varying model corona, is finally applied to a set of 53 LASCO-C2 pB images roughly evenly spaced in time from 15 to 29 March 2009. Our procedure paves the way to a time-dependent tomographic reconstruction of the coronal electron density to the whole set of LASCO-C2 images presently spanning 20 years.

  8. Miniature Dual-Corona Ionizer for Bipolar Charging of Aerosol.

    Science.gov (United States)

    Qi, Chaolong; Kulkarni, Pramod

    2013-01-01

    A corona-based bipolar charger has been developed for use in compact, field-portable mobility size spectrometers. The charger employs an aerosol flow cavity exposed to two corona ionizers producing ions of opposite polarity. Each corona ionizer houses two electrodes in parallel needle-mesh configuration and is operated at the same magnitude of corona current. Experimental measurement of detailed charge distribution of near-monodisperse particles of different diameter in the submicrometer size range showed that the charger is capable of producing well-defined, consistent bipolar charge distributions for flow rates up to 1.5 L/min and aerosol concentration up to 10(7) per cm(3). For particles with preexisting charge of +1, 0, and -1, the measured charge distributions agreed well with the theoretical distributions within the range of experimental and theoretical uncertainties. The transmission efficiency of the charger was measured to be 80% for 10 nm particles (at 0.3 L/min and 5 μA corona current) and increased with increasing diameter beyond this size. Measurement of uncharged fractions at various combinations of positive and negative corona currents showed the charger performance to be insensitive to fluctuations in corona current. Ion concentrations under positive and negative unipolar operation were estimated to be 8.2 × 10(7) and 3.37 × 10(8) cm(-3) for positive and negative ions; the n·t product value under positive corona operation was independently estimated to be 8.5 × 10(5) s/cm(3). The ion concentration estimates indicate the charger to be capable of "neutralizing" typical atmospheric and industrial aerosols in most measurement applications. The miniature size, simple and robust operation makes the charger suitable for portable mobility spectrometers.

  9. Corona development and floral nectaries of Asclepiadeae (Asclepiadoideae, Apocynaceae

    Directory of Open Access Journals (Sweden)

    Mariana Maciel Monteiro

    Full Text Available ABSTRACT Flowers of Asclepiadoideae are notable for possessing numerous nectaries and elaborate coronas, where nectar can accumulate but is not necessarily produced. Given the complexity and importance of these structures for reproduction, this study aimed to analyze the ontogeny of the corona, the structure and position of nectaries and the histochemistry of the nectar of species of Asclepiadeae. Two types of coronas were observed: androecial [C(is] and corolline (Ca. The development of the C(is-type of corona initiates opposite the stamens in all species examined with the exception of Matelea in which it begins to develop as a ring around the filament tube. Despite their morphological variation, coronas typically originate from the androecium. A notable difference among the studied species was the location of the nectaries. Primarily, they are located in the stigmatic chamber, where nectar composed of carbohydrates and lipids is produced. A secondary location of nectaries found in species of Peplonia and Matelea is within the corona, where nectar is produced and stored, composed of carbohydrates and lipids in Peplonia and only carbohydrates in Matelea. The functional role of nectar is related to the location of its production since it is a resource for pollinators and inducers of pollen germination.

  10. Personalized protein corona on nanoparticles and its clinical implications.

    Science.gov (United States)

    Corbo, Claudia; Molinaro, Roberto; Tabatabaei, Mateen; Farokhzad, Omid C; Mahmoudi, Morteza

    2017-02-28

    It is now well understood that once in contact with biological fluids, nanoscale objects lose their original identity and acquire a new biological character, referred to as a protein corona. The protein corona changes many of the physicochemical properties of nanoparticles, including size, surface charge, and aggregation state. These changes, in turn, affect the biological fate of nanoparticles, including their pharmacokinetics, biodistribution, and therapeutic efficacy. It is progressively being accepted that even slight variations in the composition of a protein source (e.g., plasma and serum) can substantially change the composition of the corona formed on the surface of the exact same nanoparticles. Recently it has been shown that the protein corona is strongly affected by the patient's specific disease. Therefore, the same nanomaterial incubated with plasma proteins of patients with different pathologies adsorb protein coronas with different compositions, giving rise to the concept of personalized protein corona. Herein, we review this concept along with recent advances on the topic, with a particular focus on clinical relevance.

  11. Nanoparticle-protein complexes mimicking corona formation in ocular environment.

    Science.gov (United States)

    Jo, Dong Hyun; Kim, Jin Hyoung; Son, Jin Gyeong; Dan, Ki Soon; Song, Sang Hoon; Lee, Tae Geol; Kim, Jeong Hun

    2016-12-01

    Nanoparticles adsorb biomolecules to form corona upon entering the biological environment. In this study, tissue-specific corona formation is provided as a way of controlling protein interaction with nanoparticles in vivo. In the vitreous, the composition of the corona was determined by the electrostatic and hydrophobic properties of the associated proteins, regardless of the material (gold and silica) or size (20- and 100-nm diameter) of the nanoparticles. To control protein adsorption, we pre-incubate 20-nm gold nanoparticles with 5 selectively enriched proteins from the corona, formed in the vitreous, to produce nanoparticle-protein complexes. Compared to bare nanoparticles, nanoparticle-protein complexes demonstrate improved binding to vascular endothelial growth factor (VEGF) in the vitreous. Furthermore, nanoparticle-protein complexes retain in vitro anti-angiogenic properties of bare nanoparticles. In particular, priming the nanoparticles (gold and silica) with tissue-specific corona proteins allows nanoparticle-protein complexes to exert better in vivo therapeutic effects by higher binding to VEGF than bare nanoparticles. These results suggest that controlled corona formation that mimics in vivo processes may be useful in the therapeutic use of nanomaterials in local environment.

  12. Inhibition of calcineurin by FK506 stimulates germinal vesicle breakdown of mouse oocytes in hypoxanthine-supplemented medium

    Science.gov (United States)

    Wang, Li; Zhen, Yan-Hong; Liu, Xiao-Ming; Cao, Jing; Wang, Yan-Ling

    2017-01-01

    Calcineurin (CN) is a serine/threonine phosphatase which plays important roles in meiosis maturation in invertebrate oocytes; however, the role of CN in mouse oocytes is relatively unexplored. In this study, we examined the expression, localization and functional roles of CN in mouse oocytes and granulosa cells. The RT-PCR results showed that the β isoform of calcineurin A subunit (Cn A) expressed significantly higher than α and γ isoforms, and the expression of Cn Aβ mRNA obviously decreased in oocytes in which germinal vesicle breakdown (GVBD) occurred, while only B1 of calcineurin B subunit (Cn B) was detected in oocytes and stably expressed during oocytes maturation. The following fluorescence experiment showed that Cn A was mainly located in the nucleus of germinal vesicle (GV) stage oocytes and gruanlosa cells, and subsequently dispersed into the entire cytoplasm after GVBD. The decline of Cn A in oocytes suggested that it may play an important role in GVBD. To further clarify the role of calcineurin during meiotic maturation, FK506 (a calcineurin inhibitor) was used in the culture medium contained hypoxanthine (HX) which could keep mouse oocytes staying at GV stage. As expected, FK506 could induce a significant elevation of GVBD rate and increase the MPF level of denuded oocytes (DOs). Furthermore, FK506 could also play an induction role of GVBD of oocytes in COCs and follicles, and the process could be counteracted by MAPK kinase inhibitor (U0126). Above all, the results implied that calcineurin might play a crucial role in development of mouse oocytes and MPF and MAPK pathways are involved in this process. PMID:28243539

  13. Pre-Flare Flows in the Corona

    Science.gov (United States)

    Wallace, A. J.; Harra, L. K.; van Driel-Gesztelyi, L.; Green, L. M.; Matthews, S. A.

    2010-12-01

    Solar flares take place in regions of strong magnetic fields and are generally accepted to be the result of a resistive instability leading to magnetic reconnection. When new flux emerges into a pre-existing active region it can act as a flare and coronal mass ejection trigger. In this study we observed active region 10955 after the emergence of small-scale additional flux at the magnetic inversion line. We found that flaring began when additional positive flux levels exceeded 1.38×1020 Mx (maxwell), approximately 7 h after the initial flux emergence. We focussed on the pre-flare activity of one B-class flare that occurred on the following day. The earliest indication of activity was a rise in the non-thermal velocity one hour before the flare. 40 min before flaring began, brightenings and pre-flare flows were observed along two loop systems in the corona, involving the new flux and the pre-existing active region loops. We discuss the possibility that reconnection between the new flux and pre-existing loops before the flare drives the flows by either generating slow mode magnetoacoustic waves or a pressure gradient between the newly reconnected loops. The subsequent B-class flare originated from fast reconnection of the same loop systems as the pre-flare flows.

  14. Measuring the Electron Temperature in the Corona

    Science.gov (United States)

    Davila, Joseph; SaintCyr, Orville C.; Reginald, Nelson

    2008-01-01

    We report on an experiment to demonstrate the feasibility of a new method to obtain the electron temperature and flow speed in the solar corona by observing the visible Kcoronal spectrum during the total solar eclipse on 29 March 2006 in Libya. Results show that this new method is indeed feasible, giving electron temperatures and speeds of 1.10 $\\pm$ 0.05 MK, 103.0 $\\pm$ 92.0 $kmsA{-l}$; 0.98 $\\pm$ 0.12 MK, 0.0 + 10.0 $kmsA{-1)s; 0.70 $\\pm$ 0.08 MK, 0.0 + 10.0 $kmsA{-l)$ at l.l{\\it R)$ {\\odot}$ in the solar north, east and west, respectively, and 0.93 $\\pm$ 0.12 MK, 0.0 + 10.0 $kmsA{-l}$ at 1.2{\\it R}$ {\\odot}$ in the solar east. This new technique could be easily used from a space-based platform in a coronagraph to produce two dimensional maps of the electron temperature and bulk flow speed at the base of the solar wind useful for the study of heliospheric structure and space weather.

  15. Titan's corona: The contribution of exothermic chemistry

    Science.gov (United States)

    De La Haye, V.; Waite, J. H.; Cravens, T. E.; Nagy, A. F.; Johnson, R. E.; Lebonnois, S.; Robertson, I. P.

    2007-11-01

    The contribution of exothermic ion and neutral chemistry to Titan's corona is studied. The production rates for fast neutrals N 2, CH 4, H, H 2, 3CH 2, CH 3, C 2H 4, C 2H 5, C 2H 6, N( 4S), NH, and HCN are determined using a coupled ion and neutral model of Titan's upper atmosphere. After production, the formation of the suprathermal particles is modeled using a two-stream simulation, as they travel simultaneously through a thermal mixture of N 2, CH 4, and H 2. The resulting suprathermal fluxes, hot density profiles, and energy distributions are compared to the N 2 and CH 4 INMS exospheric data presented in [De La Haye, V., Waite Jr., J.H., Johnson, R.E., Yelle, R.V., Cravens, T.E., Luhmann, J.G., Kasprzak, W.T., Gell, D.A., Magee, B., Leblanc, F., Michael, M., Jurac, S., Robertson, I.P., 2007. J. Geophys. Res., doi:10.1029/2006JA012222, in press], and are found insufficient for producing the suprathermal populations measured. Global losses of nitrogen atoms and carbon atoms in all forms due to exothermic chemistry are estimated to be 8.3×10 Ns and 7.2×10 Cs.

  16. Cyclosporine A, FK506, and NIM811 ameliorate prolonged CBF reduction and impaired neurovascular coupling after cortical spreading depression

    DEFF Research Database (Denmark)

    Hansen, Henning Piilgaard; Witgen, Brent Marvin; Rasmussen, Peter

    2011-01-01

    that cyclosporine A (CsA), which blocks both mPTP and CaN, ameliorates the persistent reduction of cerebral blood flow (CBF), impaired vascular reactivity, and a persistent rise in the cerebral metabolic rate of oxygen (CMRO(2)) following CSD. In addition to CsA, we used the specific mPTP blocker NIM811......), and neurovascular and neurometabolic coupling were unaffected by all three drugs under control conditions. NIM811 augmented the rise in CBF observed during CSD. Cyclosporine A and FK506 ameliorated the persistent decrease in CBF after CSD. All three drugs prevented disruption of neurovascular coupling after CSD...

  17. Development of Efficient Models of Corona Discharges Around Tall Structures

    Science.gov (United States)

    Tucker, J.; Pasko, V. P.

    2012-12-01

    This work concerns with numerical modeling of glow corona and sreamer corona discharges that occur near tall ground structures under thunderstorm conditions. Glow corona can occur when ambient electric field reaches modest values on the order of 0.2 kV/cm and when the electric field near sharp points of ground structure rises above a geometry dependent critical field required for ionization of air. Air is continuously ionized in a small region close to the surface of the structure and ions diffuse out into the surrounding air forming a corona. A downward leader approaching from a thundercloud causes a further increase in the electric field at the ground level. If the electric field rises to the point where it can support formation of streamers in air surrounding the tall structure, a streamer corona flash, or series of streamer corona flashes can be formed significantly affecting the space charge configuration formed by the preceding glow corona. The streamer corona can heat the surrounding air enough to form a self-propagating thermalized leader that is launched upward from the tall structure. This leader travels upward towards the thundercloud and connects with the downward approaching leader thus causing a lightning flash. Accurate time-dependent modeling of charge configuration created by the glow and streamer corona discharges around tall structure is an important component for understanding of the sequence of events leading to lightning attachment to the tall structure. The present work builds on principal modeling ideas developed previously in [Aleksandrov et al., J. Phys. D: Appl. Phys., 38, 1225, 2005; Bazelyan et al., Plasma Sources Sci. Technol., 17, 024015, 2008; Kowalski, E. J., Honors Thesis, Penn State Univ., University Park, PA, May 2008; Tucker and Pasko, NSF EE REU Penn State Annual Res. J., 10, 13, 2012]. The non-stationary glow and streamer coronas are modeled in spherical geometry up to the point of initiation of the upward leader. The model

  18. High-resolution spectroscopy of the R Coronae Borealis Star V Coronae Australis

    CERN Document Server

    Rao, N Kameswara

    2007-01-01

    Optical high-resolution spectra of the R Coronae Borealis star V CrA at light maximum and during minimum light arediscussed. Abundance analysis confirms previous results showing that V CrA has the composition of the small subclass of R Coronae Borealis (RCB) stars know as `minority' RCBs, i.e., the Si/Fe and S/Fe ratios are 100 times their solar values. A notable novel result for RCBs is the detection of the 1-0 Swan system $^{12}$C$^{13}$C bandhead indicating that $^{13}$C is abundant: spectrum synthesis shows that $^{12}$C/$^{13}$C is about 3 to 4. Absorption line profiles are variable at maximum light with some lines showing evidence of splitting by about 10 km s$^{-1}$. A spectrum obtained as the star was recovering from a deep minimum shows the presence of cool C$_2$ molecules with a rotational temperature of about 1200K, a temperature suggestive of gas in which carbon is condensing into soot. The presence of rapidly outflowing gas is shown by blue-shifted absorption components of the Na {\\sc i} D and K ...

  19. An XMM-Newton Study of the Coronae of $\\sigma^2$ Coronae Borealis

    CERN Document Server

    Suh, J A; Güdel, M; Paerels, F B S

    2005-01-01

    (Abridged) We present results of XMM-Newton observations of the RS CVn binary $\\sigma^2$ Coronae Borealis. The RGS and EPIC MOS2 spectra were simultaneously fitted with collisional ionization equilibrium plasma models to determine coronal abundances of various elements. Contrary to the solar first ionization potential (FIP) effect in which elements with a low FIP are overabundant in the corona compared to the solar photosphere, and contrary to the ``inverse'' FIP effect observed in several active RS CVn binaries, coronal abundance ratios in $\\sigma^2$ CrB show a complex pattern as supported by similar findings in the Chandra HETGS analysis of $\\sigma^2$ CrB with a different methodology (Osten et al. 2003). Low-FIP elements ($<10$ eV) have their abundance ratios relative to Fe consistent with the solar photospheric ratios, whereas high-FIP elements have their abundance ratios increase with increasing FIP. We find that the coronal Fe abundance is consistent with the stellar photospheric value, indicating tha...

  20. Maya角色动画中IK-FK无缝切换的技术探讨%Discussion on IK-FK Seamless Switching Technology in Maya Character Animation

    Institute of Scientific and Technical Information of China (English)

    卢景峰

    2014-01-01

    This paper describes a theory of the transformation between Ik and FK in the Maya character animation, introducing seamless switching between IK and FK, which focuses on using the method of three sets of bones together with Maya Mel lan-guages to achieve seamless transition of skeletal between IK and FK. The author hopes to inspire and help those who like three di-mensional character animation of Maya design.%该文阐述maya角色动画中IK-FK相互转换的原理,介绍几种IK-FK无缝切换的几种思路,重点探讨利用三套骨骼配合Maya mel语言实现骨骼IK-FK之间无缝转换的实现方法,希望能给喜欢maya三维角色动画设计的朋友有所启发和帮助。

  1. 眼表重建术后局用FK-506及rhEGF临床观察%The priliminary clinical observation of topical use of FK-506 and rhEGF after ocular surface reconstruction

    Institute of Scientific and Technical Information of China (English)

    林跃生; 陈家祺; 刘永民; 王敏华; 周世友; 谢汉平

    2000-01-01

    目的:寻找眼表重建术后主要并发症的有效治疗措施.方法:对32例32只严重化学伤患眼施眼表重建术(板层角膜移植、角膜移植羊膜移植术),按随机方法将研究对象分为治疗组及对照组各16眼;治疗组于术后一周局部应用0.5mg/ml的FK-506及20μg/ml的rhEGF滴眼液,对照组应用1%CsA及Solcoseryl Eye Gel,观察两组移植组织的排斥反应及上皮细胞愈合质量.结果:在随访期内,治疗组的组织排斥反应时间、发生率、预后及上皮愈合质量四个指标均明显优于对照组.结论:FK-506及rhEGF联合应用可有效提高眼表重建术的成功率.

  2. Spatial Mapping and Quantification of Soft and Hard Protein Coronas at Silver Nanocubes

    DEFF Research Database (Denmark)

    Miclaus, Teodora; Bochenkov, Vladimir; Ogaki, Ryosuke;

    2014-01-01

    Protein coronas around silver nanocubes were quantified in serum-containing media using localized surface plasmon resonances. Both soft and hard coronas showed exposure-time and concentration-dependent changes in protein surface density with time-dependent hardening. We observed spatially dependent...... kinetics of the corona-formation at cube edges/corners versus facets at short incubation times, where the polymer stabilization agent delayed corona hardening. The soft corona contained more protein than the hard corona at all time-points (8-fold difference with 10% serum conditions)....

  3. Monitoring Holes in the Sun's Corona

    Science.gov (United States)

    Kohler, Susanna

    2016-09-01

    Coronal holes are where the fast solar wind streams out of the Suns atmosphere, sending charged particles on rapid trajectories out into the solar system. A new study examines how the distribution of coronal holes has changed over the last 40 years.Coronal holes form where magnetic field lines open into space (B) instead of looping back to the solar surface (A). [Sebman81]Source of the Fast Solar WindAs a part of the Suns natural activity cycle, extremely low-density regions sometimes form in the solar corona. These coronal holes manifest themselves as dark patches in X-ray and extreme ultraviolet imaging, since the corona is much hotter than the solar surface that peeks through from underneath it.Coronal holes form when magnetic field lines open into space instead of looping back to the solar surface. In these regions, the solar atmosphere escapes via these field lines, rapidly streaming away from the Suns surface in whats known as the fast solar wind.Coronal Holes Over Space and TimeAutomated detection of coronal holes from image-based analysis is notoriously difficult. Recently, a team of scientists led by Kenichi Fujiki (ISEE, Nagoya University, Japan) has developed an automated prediction technique for coronal holes that relies instead on magnetic-field data for the Sun, obtained at the National Solar Observatorys Kitt Peak between 1975 and 2014. The team used these data to produce a database of 3335 coronal hole predictions over nearly 40 years.Latitude distribution of 2870 coronal holes (each marked by an x; color indicates polarity), overlaid on the magnetic butterfly map of the Sun. The low-latitude coronal holes display a similar butterfly pattern, in which they move closer to the equator over the course of the solar cycle. Polar coronal holes are more frequent during solar minima. [Fujiki et al. 2016]Examining trends in the coronal holes distribution in latitude and time, Fujiki and collaborators find a strong correlation between the total area covered

  4. Sadness of the City “About Edirne History and Architecture” by Rıfkı Melül Meriç

    OpenAIRE

    Ekinci, Neriman

    2014-01-01

    In his research Rıfkı Melül Meriç, wrote about the buildings which are burned,destroyed and sold one by one and also about the conservation and liquidation of the foundation buildings and about the correspondence of the prominent people of that period and shared with us.’’Şehrin Hüznü’’ (The Sadness of the City) is a intensive document for not to repeat the same stumbles which was made in the past. Finally, let's finish by the word of Rıfkı Melul Meric; "Nations, their past, their vaunted...

  5. Posaconazole exhibits in vitro and in vivo synergistic antifungal activity with caspofungin or FK506 against Candida albicans.

    Directory of Open Access Journals (Sweden)

    Ying-Lien Chen

    Full Text Available The object of this study was to test whether posaconazole, a broad-spectrum antifungal agent inhibiting ergosterol biosynthesis, exhibits synergy with the β-1,3 glucan synthase inhibitor caspofungin or the calcineurin inhibitor FK506 against the human fungal pathogen Candida albicans. Although current drug treatments for Candida infection are often efficacious, the available antifungal armamentarium may not be keeping pace with the increasing incidence of drug resistant strains. The development of drug combinations or novel antifungal drugs to address emerging drug resistance is therefore of general importance. Combination drug therapies are employed to treat patients with HIV, cancer, or tuberculosis, and has considerable promise in the treatment of fungal infections like cryptococcal meningitis and C. albicans infections. Our studies reported here demonstrate that posaconazole exhibits in vitro synergy with caspofungin or FK506 against drug susceptible or resistant C. albicans strains. Furthermore, these combinations also show in vivo synergy against C. albicans strain SC5314 and its derived echinocandin-resistant mutants, which harbor an S645Y mutation in the CaFks1 β-1,3 glucan synthase drug target, suggesting potential therapeutic applicability for these combinations in the future.

  6. CORONA DISCHARGE IGNITION FOR ADVANCED STATIONARY NATURAL GAS ENGINES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Paul D. Ronney

    2003-09-12

    An ignition source was constructed that is capable of producing a pulsed corona discharge for the purpose of igniting mixtures in a test chamber. This corona generator is adaptable for use as the ignition source for one cylinder on a test engine. The first tests were performed in a cylindrical shaped chamber to study the characteristics of the corona and analyze various electrode geometries. Next a test chamber was constructed that closely represented the dimensions of the combustion chamber of the test engine at USC. Combustion tests were performed in this chamber and various electrode diameters and geometries were tested. The data acquisition and control system hardware for the USC engine lab was updated with new equipment. New software was also developed to perform the engine control and data acquisition functions. Work is underway to design a corona electrode that will fit in the new test engine and be capable igniting the mixture in one cylinder at first and eventually in all four cylinders. A test engine was purchased for the project that has two spark plug ports per cylinder. With this configuration it will be possible to switch between corona ignition and conventional spark plug ignition without making any mechanical modifications.

  7. Evidence for wave heating in the solar corona.

    Science.gov (United States)

    Hahn, Michael

    2013-07-01

    The temperature of the Sun increases over a short distance from a few thousand degrees in the photosphere to over a million degrees in the corona. To understand coronal heating is one of the major problems in astrophysics. There is general agreement that the energy source is convective motion in and below the photosphere. It remains to determine how this mechanical energy is transported outward into the corona and then deposited as heat. Two classes of models have been proposed, namely those that rely on magnetic reconnection and those that rely on waves, particularly Alfvén waves. There is increasing evidence that waves are ubiquitous in the corona. However, a difficulty for wave-driven models has been that most theories predict Alfvén waves to be undamped in the corona, and therefore they cannot dissipate their energy into heat. Our research has shown unambiguous observational evidence that the waves do damp at sufficiently low heights in the corona to be important for coronal heating.

  8. Low-frequency heliographic observations of the quiet Sun corona

    Science.gov (United States)

    Stanislavsky, A. A.; Koval, A. A.; Konovalenko, A. A.

    2013-12-01

    We present new results of heliographic observations of quiet-Sun radio emission fulfilled by the UTR-2 radio telescope. The solar corona investigations have been made close to the last solar minimum (Cycle 23) in the late August and early September of 2010 by means of the two-dimensional heliograph within 16.5-33 MHz. Moreover, the UTR-2 radio telescope was used also as an 1-D heliograph for one-dimensional scanning of the Sun at the beginning of September 2010 as well as in short-time observational campaigns in April and August of 2012. The average values of integral flux density of the undisturbed Sun continuum emission at different frequencies have been found. Using the data, we have determined the spectral index of quiet-Sun radio emission in the range 16.5-200 MHz. It is equal to -2.1±0.1. The brightness distribution maps of outer solar corona at frequencies 20.0 MHz and 26.0 MHz have been obtained. The angular sizes of radio Sun were estimated. It is found that the solar corona at these frequencies is stretched-out along equatorial direction. The coefficient of corona ellipticity varies slightly during above period. Its mean magnitudes are equal to ≈ 0.75 and ≈ 0.73 at 20.0 MHz and 26.0 MHz, respectively. The presented results for continuum emission of solar corona conform with being ones at higher frequencies.

  9. Inhibitory effect of a novel histone deacetylases inhibitor FK228 on human colon cancer HCT-116 cells in vitro and in vivo%新型组蛋白去乙酰化酶抑制剂FK228对人结肠癌细胞HCT-116的体内外抑制作用

    Institute of Scientific and Technical Information of China (English)

    徐东波; 望运玲; 岳源; 武双婵; 丁虹

    2013-01-01

    Objective To investigate the inhibitory effects of a novel histone deacetylases inhibitor FK228 on human colon cancer HCT-116 cells in vitro and in vivo,and evaluate its toxicity and side effects.Methods The in vitro growth inhibitions of HCT-116 cells by different concentrations of FK228 and 5-Fu for 24,48 and 72 h were assessed by CCK-8 assay.BALB/c nude mouse models of tumor xenografts were prepared by subcutaneous implantation of tumor tissue,and 4 mg/kg FK228 and 50 mg/kg 5-Fu were i.p.injected,respectively.The inhibitory effects on tumor growth,hematology,and liver and kidney function were evaluated.Results CCK-8 assay indicated that FK228 had an obvious growth inhibitory effect on HCT-116 cells in a dose-and time-dependent manner.The IC50 of FK228 in HCT-116 cells was 12.05 ng/ml for48 h,while the IC50 of 5-Fu was 18.92 μg/ml.At 20 days after FK228 and 5-Fu treatment,the tumor volume of the FK228 group was (139.71 ± 44.54)mm3,significantly lower than that of the 5-Fu group [(282.28 ± 58.81) mm3] and that of the model group [(520.65 ± 39.73) mm3,P < 0.01 for both].The average tumor weight was (0.07 ± 0.02) g in the FK228 group,significantly lower than that of the 5-Fu group [(0.20 ± 0.08) g,P < 0.01].The tumor growth inhibition rate of the FK228 group was 73.2%,significantly higher than that of the 5-Fu group (45.8%,P <0.01).The ALT levels of the FK228 and 5-Fu groups were significantly higher than that of the model group (P < 0.01).The BUN of 5-Fu group was significantly higher than that of the model group (P < 0.01),but the BUN of FK228 group was not significantly different from that of the blank and control groups (P > 0.05 for both).Routine blood test showed that WBC,RBC,Hb and PLT of the 5-Fu group were significantly lower than those of the model group (P < 0.05 for all),but only WBC of the FK228 group was significantly lower than that of the model group (P < 0.05).The pathological examination using HE staining revealed that in

  10. Shape parameters of the solar corona from 1991 to 2016

    Science.gov (United States)

    Priyatikanto, Rhorom

    2016-12-01

    The global structure of the solar corona observed in the optical window is governed by the global magnetic field with different characteristics over a solar activity cycle. The Ludendorff flattening index has become a popular measure of global structure of the solar corona as observed during an eclipse. In this study, 15 digital images of the solar corona from 1991 to 2016 were analyzed in order to construct coronal flattening profiles as a function of radius. In most cases, the profile can be modeled with a 2nd order polynomial function so that the radius with maximum flattening index (Rmax) can be determined. Along with this value, Ludendorff index (a + b) was also calculated. Both Ludendorff index and Rmax show anti-correlation with monthly sunspot number, though the Rmax values are more scattered. The variation in Rmax can be regarded as the impact of the changing coronal brightness profile over the equator.

  11. Shape Parameters of 1991 to 2016 Solar Corona

    CERN Document Server

    Priyatikanto, Rhorom

    2016-01-01

    The global structure of solar corona observed in optical window is governed by the global magnetic field with different characteristics over solar activity cycle. Ludendorff flattening index becomes a popular measure of the global structure of solar corona as observed during eclipse. In this study, 15 digital images of solar corona from 1991 to 2016 were analyzed in order to construct the coronal flattening profiles as a function of radius. In most of the cases, the profile can be modeled with 2nd order polynomial function so that the radius with maximum flattening index ($R_{\\text{max}}$) can be determined. Along with this value, Ludendorff index ($a+b$) was also calculated. Both Ludendorff index and $R_{\\text{max}}$ show anti-correlation with monthly sunspot number, though the $R_{\\text{max}}$ values are more scattered. The variation of $R_{\\text{max}}$ can be regarded as the impact of changing coronal brightness profile over equator.

  12. Triggering Excimer Lasers by Photoionization from Corona Discharges

    Science.gov (United States)

    Xiong, Zhongmin; Duffey, Thomas; Brown, Daniel; Kushner, Mark

    2009-10-01

    High repetition rate ArF (192 nm) excimer lasers are used for photolithography sources in microelectronics fabrication. In highly attaching gas mixtures, preionization is critical to obtaining stable, reproducible glow discharges. Photoionization from a separate corona discharge is one technique for preionization which triggers the subsequent electron avalanche between the main electrodes. Photoionization triggering of an ArF excimer laser sustained in multi-atmosphere Ne/Ar/F2/Xe gas mixtures has been investigated using a 2-dimensional plasma hydrodynamics model including radiation transport. Continuity equations for charged and neutral species, and Poisson's equation are solved coincident with the electron temperature with transport coefficients obtained from solutions of Boltzmann's equation. Photoionizing radiation is produced by a surface discharge which propagates along a corona-bar located adjacent to the discharge electrodes. The consequences of pulse power waveform, corona bar location, capacitance and gas mixture on uniformity, symmetry and gain of the avalanche discharge will be discussed.

  13. Influence of corona charging in cellular polyethylene film

    Energy Technology Data Exchange (ETDEWEB)

    Ortega Brana, Gustavo; Magraner, Francisco; Quijano, Alfredo [Instituto Tecnologico de la Energia (ITE), Av. Juan de la Cierva 24, Parque Tecnologico de Valencia, 46980 Paterna-Valencia (Spain); Llovera Segovia, Pedro, E-mail: gustavo.ortega@ite.es [Instituto de TecnologIa Electrica - Universitat Politecnica de Valencia, Camino de Vera s/n 46022-Valencia (Spain)

    2011-06-23

    Cellular polymers have recently attracted attention for their property of exhibiting a piezoelectric constant when they are electrically charged. The electrostatic charge generated in the voids by the internal discharges creates and internal macrodipole which is responsible for the piezoelectric effect. Charging by corona discharge is the most used method for cellular polymers. Many works has been published on polypropylene and polyethylene films mainly focused on the required expansion process or on the results obtained for raw cellular materials electrically activated. Our work is based on commercial polyethylene cellular films which have been physically characterized and electrically activated. The effect of thermal treatment, physical uniaxial or biaxial stretching and corona charging was investigated. The new method of corona charging improved the piezoelectric constant under other activation conditions.

  14. Simulation of low temperature atmospheric pressure corona discharge in helium

    Science.gov (United States)

    Bekasov, Vladimir; Kirsanov, Gennady; Eliseev, Stepan; Kudryavtsev, Anatoly; Sisoev, Sergey

    2015-11-01

    The main objective of this work was to construct a numerical model of corona discharge in helium at atmospheric pressure. The calculation was based on the two-dimensional hybrid model. Two different plasma-chemical models were considered. Models were built for RF corona and negative DC corona discharge. The system of equations is solved by the finite element method in the COMSOL Multiphysics. Main parameters of the discharge (the density of charged and excited particles, the electron temperature) and their dependence on the input parameters of the model (geometry, electrode voltage, power) were calculated. The calculations showed that the shape of the electron distribution near the electrode depends on the discharge power. The neutral gas heating data obtained will allow predicting the temperature of the gases at the designing of atmospheric pressure helium plasma sources.

  15. INDUCED SCATTERING LIMITS ON FAST RADIO BURSTS FROM STELLAR CORONAE

    Energy Technology Data Exchange (ETDEWEB)

    Lyubarsky, Yuri [Physics Department, Ben-Gurion University, P.O.B. 653, Beer-Sheva 84105 (Israel); Ostrovska, Sofiya [Department of Mathematics, Atilim University, Incek 06836, Ankara (Turkey)

    2016-02-10

    The origin of fast radio bursts remains a puzzle. Suggestions have been made that they are produced within the Earth’s atmosphere, in stellar coronae, in other galaxies, or at cosmological distances. If they are extraterrestrial, the implied brightness temperature is very high, and therefore the induced scattering places constraints on possible models. In this paper, constraints are obtained on flares from coronae of nearby stars. It is shown that the radio pulses with the observed power could not be generated if the plasma density within and in the nearest vicinity of the source is as high as is necessary to provide the observed dispersion measure. However, one cannot exclude the possibility that the pulses are generated within a bubble with a very low density and pass through the dense plasma only in the outer corona.

  16. The Structure and Dynamics of the Corona - Heliosphere Connection

    Science.gov (United States)

    Antiochos, Spiro K.; Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav; Zurbuchen, Thomas H.

    2011-01-01

    Determining the source at the Sun of the slow solar wind is one of the major unsolved problems in solar and heliospheric physics. First, we review the existing theories for the slow wind and argue that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory in which the slow wind originates from the continuous opening and closing of narrow open field corridors, the S-Web model, is described. Support for the S-Web model is derived from MHD solutions for the quasisteady corona and wind during the time of the August 1, 2008 eclipse. Additionally, we perform fully dynamic numerical simulations of the corona and heliosphere in order to test the S-Web model as well as the interchange model proposed by Fisk and co-workers. We discuss the implications of our simulations for the competing theories and for understanding the corona - heliosphere connection, in general.

  17. Emergence of magnetic flux from the convection zone into the corona

    DEFF Research Database (Denmark)

    Archontis, Vasilis; Moreno-insertis, F.; Galsgaard, Klaus;

    2004-01-01

    Sun: corona/ Sun: magentic fields/ Sun: interior/ magnetohydrodynamics (MHD)/methods: numerical/ stars: activity......Sun: corona/ Sun: magentic fields/ Sun: interior/ magnetohydrodynamics (MHD)/methods: numerical/ stars: activity...

  18. Optical emission spectroscopy of point-plane corona and back-corona discharges in air

    Science.gov (United States)

    Czech, T.; Sobczyk, A. T.; Jaworek, A.

    2011-12-01

    Results of spectroscopic investigations and current-voltage characteristics of corona discharge and back discharge on fly-ash layer, generated in point-plane electrode geometry in air at atmospheric pressure are presented in the paper. The characteristics of both discharges are similar but differ in the current and voltage ranges of all the discharge forms distinguished during the experiments. Three forms of back discharge, for positive and negative polarity, were investigated: glow, streamer and low-current back-arc. In order to characterize ionisation and excitation processes in back discharge, the emission spectra were measured and compared with those obtained for normal corona discharge generated in the same electrode configuration but with fly ash layer removed. The emission spectra were measured in two discharge zones: near the tip of needle electrode and near the plate. Visual forms of the discharge were recorded with digital camera and referred to current-voltage characteristics and emission spectra. The measurements have shown that spectral lines emitted by back discharge depend on the form of discharge and the discharge current. From the comparison of the spectral lines of back and normal discharges an effect of fly ash layer on the discharge morphology can be determined. The recorded emission spectra formed by ionised gas and plasma near the needle electrode and fly ash layer are different. It should be noted that in back arc emission, spectral lines of fly ash layer components can be distinguished. On the other hand, in needle zone, the emission of high intensity N2 second positive system and NO γ lines can be noticed. Regardless of these gaseous lines, also atomic lines of dust layer were present in the spectrum. The differences in spectra of back discharge for positive and negative polarities of the needle electrode have been explained by considering the kind of ions generated in the crater in fly ash layer. The aim of these studies is to better

  19. The Role of Magnetic Helicity in Structuring the Solar Corona

    Science.gov (United States)

    Knizhnik, K. J.; Antiochos, S. K.; DeVore, C. R.

    2017-01-01

    Two of the most widely observed and striking features of the Sun's magnetic field are coronal loops, which are smooth and laminar, and prominences or filaments, which are strongly sheared. Loops are puzzling because they show little evidence of tangling or braiding, at least on the quiet Sun, despite the chaotic nature of the solar surface convection. Prominences are mysterious because the origin of their underlying magnetic structure—filament channels—is poorly understood at best. These two types of features would seem to be quite unrelated and wholly distinct. We argue that, on the contrary, they are inextricably linked and result from a single process: the injection of magnetic helicity into the corona by photospheric motions and the subsequent evolution of this helicity by coronal reconnection. In this paper, we present numerical simulations of the response of a Parker (1972) corona to photospheric driving motions that have varying degrees of helicity preference. We obtain four main conclusions: (1) in agreement with the helicity condensation model of Antiochos (2013), the inverse cascade of helicity by magnetic reconnection in the corona results in the formation of filament channels localized about polarity inversion lines; (2) this same process removes most complex fine structure from the rest of the corona, resulting in smooth and laminar coronal loops; (3) the amount of remnant tangling in coronal loops is inversely dependent on the net helicity injected by the driving motions; and (4) the structure of the solar corona depends only on the helicity preference of the driving motions and not on their detailed time dependence. We discuss the implications of our results for high-resolution observations of the corona.

  20. Improvement of aluminum/polyethylene adhesion through corona discharge

    Science.gov (United States)

    Popelka, Anton; Krupa, Igor; Novák, Igor; Al-Maadeed, Mariam Ali S. A.; Ouederni, Mabrouk

    2017-01-01

    Polyethylene (PE) is often used in several industrial applications including the building, packaging and transport industries. Aluminum (Al) is widely used in different applications in the automotive, railway, aeronautic, and naval industries because of its excellent mechanical and chemical properties. Laminates prepared from Al and PE lead to an enhancement in physical and mechanical properties. These materials play a main role in the packaging and building sectors, such as in TetraPak containers and aluminum composite panels. The main problem observed is associated with the adhesion between polymers and metals. This research focused on investigating the enhancement in the adhesion of the PE/Al laminate using the corona discharge. The corona treatment of the surfaces led to a significant increase in the adhesion of the PE/Al laminate as a result of improved surface properties confirmed by peel test measurements. Moreover, the positive effect of the corona treatment in combination with a primer on the improvement of adhesion characteristics was observed too. Different analytical techniques were employed to characterize the effect of the corona treatment on the improvement in adhesion of PE/Al. A significant increase in wettability was confirmed by the measurement of contact angles. Changes in the surface morphology of the PE and Al surface, after the corona treatments at different operating conditions, were observed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to analyze changes in chemical composition after the corona discharge effect on PE and Al surfaces.

  1. The Role of Magnetic Helicity in Structuring the Solar Corona

    Science.gov (United States)

    Knizhnik, K. J.; Antiochos, S. K.; DeVore, C. R.

    2017-01-01

    Two of the most widely observed and striking features of the Suns magnetic field are coronal loops, which are smooth and laminar, and prominences or filaments, which are strongly sheared. Loops are puzzling because they show little evidence of tangling or braiding, at least on the quiet Sun, despite the chaotic nature of the solar surface convection. Prominences are mysterious because the origin of their underlying magnetic structure filament channels is poorly understood at best. These two types of features would seem to be quite unrelated and wholly distinct. We argue that, on the contrary, they are inextricably linked and result from a single process: the injection of magnetic helicity into the corona by photospheric motions and the subsequent evolution of this helicity by coronal reconnection. In this paper, we present numerical simulations of the response of a Parker (1972) corona to photospheric driving motions that have varying degrees of helicity preference. We obtain four main conclusions: (1) in agreement with the helicity condensation model of Antiochos (2013), the inverse cascade of helicity by magnetic reconnection in the corona results in the formation of filament channels localized about polarity inversion lines; (2) this same process removes most complex fine structure from the rest of the corona, resulting in smooth and laminar coronal loops; (3) the amount of remnant tangling in coronal loops is inversely dependent on the net helicity injected by the driving motions; and (4) the structure of the solar corona depends only on the helicity preference of the driving motions and not on their detailed time dependence. We discuss the implications of our results for high-resolution observations of the corona.

  2. Modeling Jets in the Corona and Solar Wind

    CERN Document Server

    Torok, T; Titov, V S; Leake, J E; Mikic, Z; Linker, J A; Linton, M G

    2015-01-01

    Coronal jets are transient, collimated eruptions that occur in regions of predominantly open magnetic field in the solar corona. Our understanding of these events has greatly evolved in recent years but several open questions, such as the contribution of coronal jets to the solar wind, remain. Here we present an overview of the observations and numerical modeling of coronal jets, followed by a brief description of "next-generation" simulations that include an advanced description of the energy transfer in the corona ("thermodynamic MHD"), large spherical computational domains, and the solar wind. These new models will allow us to address some of the open questions.

  3. Corona graphs as a model of small-world networks

    Science.gov (United States)

    Lv, Qian; Yi, Yuhao; Zhang, Zhongzhi

    2015-11-01

    We introduce recursive corona graphs as a model of small-world networks. We investigate analytically the critical characteristics of the model, including order and size, degree distribution, average path length, clustering coefficient, and the number of spanning trees, as well as Kirchhoff index. Furthermore, we study the spectra for the adjacency matrix and the Laplacian matrix for the model. We obtain explicit results for all the quantities of the recursive corona graphs, which are similar to those observed in real-life networks.

  4. Branch Structure of Corona Discharge:Experimental Simulation and Chemical Properties

    Institute of Scientific and Technical Information of China (English)

    邹吉军; 刘昌俊

    2004-01-01

    The branch structure of corona discharge has been investigated via C2H2 corona discharge. Carbon filament with excellent branch structure is formed in the discharge. This carbon filament offers a direct mimic of the branch structure of corona discharge. It providesa very useful way to study on the average energy, physical and chemical characteristics of coronadischarge. On this basis, the chemical property of corona discharge for methane conversion is discussed.

  5. Corona Discharges in Atmospheric Air Between a Wire and Two Plates

    OpenAIRE

    Bérard, Philippe; Lacoste, Deanna,; Laux, C.

    2011-01-01

    International audience; The corona discharge obtained in atmospheric air between a wire and two plates is presented. For the configuration studied and the voltage applied, the current is steady for the positive corona and exhibits Trichel pulses in the negative corona. The positive corona produces a homogeneous blue halo around the wire, whereas the negative discharge produces evenly spaced spots on the wire surface. We verified the analytic prediction that the ionic wind varies as the square...

  6. Cyclosporin a, but not FK506, induces osmotic lysis of pancreas zymogen granules, intra-acinar enzyme release, and lysosome instability by activating K+ channel.

    Science.gov (United States)

    Lee, Wing-Kee; Braun, Matthias; Langelüddecke, Christian; Thévenod, Frank

    2012-05-01

    The immunosuppressant tacrolimus (FK506) has improved pancreas allograft survival compared with cyclosporin A (CsA), possibly because of reduced acute pancreatitis following ischemia-reperfusion injury. Ion permeabilities in zymogen granule (ZG) membranes, including a KCNQ1 K channel, promote hormone-stimulated enzyme secretion. We investigated whether a differential modulation of ZG and lysosomal ion permeabilities and enzyme secretion by CsA/FK506 contributes to pancreatitis. Rat ZGs and lysosomes were isolated by gradient centrifugation, ion permeabilities assayed by osmotic lysis, and single-channel currents recorded in a planar lipid bilayer. Amylase release was measured in permeabilized acini and lysosomal cathepsin B release detected by immunoblotting. CsA (1-10 μM), but not FK506, enhanced ZGs osmotic lysis by selectively increasing K permeability up to 5-fold. Zymogen granule membrane K channels showed ∼2-fold increased single-channel open probability with CsA only. Cyclosporin A selectively increased basal (∼2-fold), but not cholecystokinin-octapeptide (1 nM)-induced amylase secretion in K medium only. Cyclosporin A (5 μM), but not FK506, increased cathepsin B release from lysosomes. Cyclosporin A selectively opens the ZG K channel and induces cathepsin B release from lysosomes, which cause increased in situ lysis of ZGs and may aggravate or fuel acute allograft pancreatitis following hypoxia-reperfusion injury.

  7. Signal therapy of breast cancers by the HDAC inhibitor FK228 that blocks the activation of PAK1 and abrogates the tamoxifen-resistance.

    Science.gov (United States)

    Hirokawa, Yumiko; Arnold, Melissa; Nakajima, Hidenori; Zalcberg, John; Maruta, Hiroshi

    2005-09-01

    PAK1, a Rac/CDC42-dependent Ser/Thr kinase, is required for both neurofibromatosis (NF) and RAS transformation in vivo. FK228, a histone deacetylase (HDAC) inhibitor, activates a very specific set of genes such as the tumor suppressor WAF1, an inhibitor of cyclin-dependent kinases (CDKs), and suppresses the growth of these tumors. In addition, this drug downregulates cyclin D1, which is upregulated by RAS through PAK1, in breast cancers. In this study, we demonstrate that FK228 at 0.1-1 nM significantly reduces the kinase activity of PAK1 in these cells, without affecting the protein level of PAK1. Interestingly, estrogen receptor (ER) and PAK1 mutually activate each other in breast cancers. Here we provide an evidence suggesting that breast cancers require PAK1 for their estrogen-dependent growth. Moreover, the treatment with FK228 strongly inhibits the estrogen-dependent growth of human breast cancers (both tamoxifen-sensitive and resistant cell lines) in vivo, suggesting that FK228 and other anti-PAK1 drugs would be useful for the treatment of breast cancers which become resistant to currently used estrogen antagonists such as tamoxifen.

  8. 75 FR 8395 - Bunker Hill Groundwater Basin, Riverside-Corona Feeder Project, San Bernardino and Riverside...

    Science.gov (United States)

    2010-02-24

    ... Bureau of Reclamation Bunker Hill Groundwater Basin, Riverside-Corona Feeder Project, San Bernardino and.../EIR for the proposed Riverside-Corona Feeder Project. The public and agencies are invited to comment..., and construction of the Riverside-Corona Feeder Project including: (i) 20 groundwater wells;...

  9. 76 FR 3655 - Bunker Hill Groundwater Basin, Riverside-Corona Feeder Project, San Bernardino and Riverside...

    Science.gov (United States)

    2011-01-20

    ... Bureau of Reclamation Bunker Hill Groundwater Basin, Riverside-Corona Feeder Project, San Bernardino and.../DEIS) for the proposed Riverside-Corona Feeder (RCF) Project. Interested parties are invited to comment..., 555 West 6th Street, San Bernardino, California 92410 Corona Public Library, 650 South Main...

  10. Off-limb EUV observations of the solar corona and transients with the CORONAS-F/SPIRIT telescope-coronagraph

    Directory of Open Access Journals (Sweden)

    V. Slemzin

    2008-10-01

    Full Text Available The SPIRIT telescope aboard the CORONAS-F satellite (in orbit from 26 July 2001 to 5 December 2005, observed the off-limb solar corona in the 175 Å (Fe IX, X and XI lines and 304 Å (He II and Si XI lines bands. In the coronagraphic mode the mirror was tilted to image the corona at the distance of 1.1...5 Rsun from the solar center, the outer occulter blocked the disk radiation and the detector sensitivity was enhanced. This intermediate region between the fields of view of ordinary extreme-ultraviolet (EUV telescopes and most of the white-light (WL coronagraphs is responsible for forming the streamer belt, acceleration of ejected matter and emergence of slow and fast solar wind. We present here the results of continuous coronagraphic EUV observations of the solar corona carried out during two weeks in June and December 2002. The images showed a "diffuse" (unresolved component of the corona seen in both bands, and non-radial, ray-like structures seen only in the 175 Å band, which can be associated with a streamer base. The correlations between latitudinal distributions of the EUV brightness in the corona and at the limb were found to be high in 304 Å at all distances and in 175 Å only below 1.5 Rsun. The temporal correlation of the coronal brightness along the west radial line, with the brightness at the underlying limb region was significant in both bands, independent of the distance. On 2 February 2003 SPIRIT observed an expansion of a transient associated with a prominence eruption seen only in the 304 Å band. The SPIRIT data have been compared with the corresponding data of the SOHO LASCO, EIT and UVCS instruments.

  11. Polymer micelles with hydrophobic core and ionic amphiphilic corona. 1. Statistical distribution of charged and nonpolar units in corona.

    Science.gov (United States)

    Lysenko, Evgeny A; Kulebyakina, Alevtina I; Chelushkin, Pavel S; Rumyantsev, Artem M; Kramarenko, Elena Yu; Zezin, Alexander B

    2012-12-11

    Polymer micelles with hydrophobic polystyrene (PS) core and ionic amphiphilic corona from charged N-ethyl-4-vinylpyridinium bromide (EVP) and uncharged 4-vinylpyridine (4VP) units spontaneously self-assembled from PS-block-poly(4VP-stat-EVP) macromolecules in mixed dimethylformamide/methanol/water solvent. The fraction of statistically distributed EVP units in corona-forming block is β = [EVP]/([EVP]+[4VP]) = 0.3-1. Micelles were transferred into water via dialysis technique, and pH was adjusted to 9, where 4VP is insoluble. Structural characteristics of micelles were investigated both experimentally and theoretically as a function of corona composition β. Methods of dynamic and static light scattering, electrophoretic mobility measurements, sedimentation velocity, transmission electron microscopy, and UV spectrophotometry were applied. All micelles possessed spherical morphology. The aggregation number, structure, and electrophoretic mobility of micelles changed in a jumplike manner near β ~ 0.6-0.75. Below and above this region, micelle characteristics were constant or insignificantly changed upon β. Theoretical dependencies for micelle aggregation number, corona dimensions, and fraction of small counterions outside corona versus β were derived via minimization the micelle free energy, taking into account surface, volume, electrostatic, and elastic contributions of chain units and translational entropy of mobile counterions. Theoretical estimations also point onto a sharp structural transition at a certain corona composition. The abrupt reorganization of micelle structure at β ~ 0.6-0.75 entails dramatic changes in micelle dispersion stability in the presence of NaCl or in the presence of oppositely charged polymeric (sodium polymethacrylate) or amphiphilic (sodium dodecyl sulfate) complexing agents.

  12. Nanoparticles-cell association predicted by protein corona fingerprints

    Science.gov (United States)

    Palchetti, S.; Digiacomo, L.; Pozzi, D.; Peruzzi, G.; Micarelli, E.; Mahmoudi, M.; Caracciolo, G.

    2016-06-01

    In a physiological environment (e.g., blood and interstitial fluids) nanoparticles (NPs) will bind proteins shaping a ``protein corona'' layer. The long-lived protein layer tightly bound to the NP surface is referred to as the hard corona (HC) and encodes information that controls NP bioactivity (e.g. cellular association, cellular signaling pathways, biodistribution, and toxicity). Decrypting this complex code has become a priority to predict the NP biological outcomes. Here, we use a library of 16 lipid NPs of varying size (Ø ~ 100-250 nm) and surface chemistry (unmodified and PEGylated) to investigate the relationships between NP physicochemical properties (nanoparticle size, aggregation state and surface charge), protein corona fingerprints (PCFs), and NP-cell association. We found out that none of the NPs' physicochemical properties alone was exclusively able to account for association with human cervical cancer cell line (HeLa). For the entire library of NPs, a total of 436 distinct serum proteins were detected. We developed a predictive-validation modeling that provides a means of assessing the relative significance of the identified corona proteins. Interestingly, a minor fraction of the HC, which consists of only 8 PCFs were identified as main promoters of NP association with HeLa cells. Remarkably, identified PCFs have several receptors with high level of expression on the plasma membrane of HeLa cells.In a physiological environment (e.g., blood and interstitial fluids) nanoparticles (NPs) will bind proteins shaping a ``protein corona'' layer. The long-lived protein layer tightly bound to the NP surface is referred to as the hard corona (HC) and encodes information that controls NP bioactivity (e.g. cellular association, cellular signaling pathways, biodistribution, and toxicity). Decrypting this complex code has become a priority to predict the NP biological outcomes. Here, we use a library of 16 lipid NPs of varying size (Ø ~ 100-250 nm) and surface

  13. Simultaneous Observation of High Temperature Plasma of Solar Corona By TESIS CORONAS-PHOTON and XRT Hinode.

    Science.gov (United States)

    Reva, A.; Kuzin, S.; Bogachev, S.; Shestov, S.

    2012-05-01

    The Mg XII spectroheliograph is a part of instrumentation complex TESIS (satellite CORONAS-PHOTON). This instrument builds monochromatic images of hot plasma of the solar corona (λ = 8.42 Å, T>5 MK). The Mg XII spectroheliograph observed hot plasma in the non-flaring active-region NOAA 11019 during nine days. We reconstructed DEM of this active region with the help of genetic algorithm (we used data of the Mg XII spectroheliograph, XRT and EIT). Emission measure of the hot component amounts 1 % of the emission measure of the cool component.

  14. Functional recovery of axoplasmic transport of regenerative peripheral nerve promoted by FK506%FK506缓释剂促进周围神经轴浆运输功能恢复的实验研究

    Institute of Scientific and Technical Information of China (English)

    李强; 伍亚民; 申屠刚; 徐云钦; 王刚

    2011-01-01

    目的 探讨FK506缓释剂对周围神经轴浆运输功能恢复的促进作用.方法 取48只SD大鼠,应用自行研制的梭形双通道桥接管桥接长10 mm的大鼠坐骨神经缺损.根据梭形管的2支管内加入的药物不同将动物随机均分为A组(24只2支管内均加入几丁糖凝胶)、B组[24只,一侧支管内注入几丁糖和FK506(B1组),另一侧支管内注入几丁糖和等渗生理盐水(B2组)].术后12、16周对再生神经行辣根过氧化物酶和核黄逆行示踪,术后16周行再生神经传导速度测定和透射电镜观察.结果 术后12、16周,透射电镜观察到A组2支管内再生纤维无明显差异,B1组较B2组再生纤维数量多,排列整齐,粗细均匀;辣根过氧化物酶和核黄显示:与B2组相比,B1组再生神经示踪后,脊髓内被标记的阳性神经元数目多,分布稠密;B1组神经传导速度为35.62 m/s +3.23 m/s,B2组为22.62 m/s±2.12 m/s,两组比较差异有统计学意义(P<0.05).结论 FK506缓释剂对周围神经再生纤维形态结构和功能的恢复具有促进作用.%Objective To explore the effect of FK506 (tacrolimus) on functional recovery of axoplasmic transport of the regenerative peripheral nerve.Methods Forty-eight Sprague-Dawley rats with 10 mm gap of sciatic nerve were randomly divided into 2 even groups.The nerve defects were bridged with our self-designed double-channel nerve conduits of fusiform shape.In group A,100 μL of chitin for medical use was injected into each of the 2 channels of the conduit; in group B,after 100 μL of chitin was injected into each of the 2 channels,one channel of the conduit was injected with 10 μL of FK506 (subgroup B1 ) and the other with 10 μL of isotonic saline (subgroup B2).At 12 and 16 weeks after operation,we evaluated axoplasmic transport of the regenerative nerve in the 2 channels with horseradish peroxidase(HRP) and nuclear yellow(NY) observations.At 16 weeks regenerative nerve conduction velocity(NCV) was

  15. Corona discharges from a windmill and its lightning protection tower in winter thunderstorms

    Science.gov (United States)

    Wu, Ting; Wang, Daohong; Rison, William; Thomas, Ronald J.; Edens, Harald E.; Takagi, Nobuyuki; Krehbiel, Paul R.

    2017-05-01

    This paper presents lightning mapping array (LMA) observations of corona discharges from a windmill and its lightning protection tower in winter thunderstorms in Japan. Corona discharges from the windmill, called windmill coronas, and those from the tower, called tower coronas, are distinctly different. Windmill coronas occur with periodic bursts, generally radiate larger power, and possibly develop to higher altitudes than tower coronas do. A strong negative electric field is necessary for the frequent production of tower coronas but is not apparently related with windmill coronas. These differences are due to the periodic rotation of the windmill and the moving blades which can escape space charges produced by corona discharges and sustain a large local electric field. The production period of windmill coronas is related with the rotation period of the windmill. Surprisingly, for one rotation of the windmill, only two out of the three blades produce detectable discharges and source powers of discharges from these two blades are different. The reason for this phenomenon is still unclear. For tower coronas, the source rate can get very high only when there is a strong negative electric field, and the source power can get very high only when the source rate is very low. The relationship between corona discharges and lightning flashes is investigated. There is no direct evidence that corona discharges can increase the chance of upward leader initiation, but nearby lightning flashes can increase the source rate of corona discharges right after the flashes. The peak of the source height distribution of corona discharges is about 100 m higher than the top of the windmill and the top of the tower. Possible reasons for this result are discussed.

  16. Semi-analytical modelling of positive corona discharge in air

    Science.gov (United States)

    Pontiga, Francisco; Yanallah, Khelifa; Chen, Junhong

    2013-09-01

    Semianalytical approximate solutions of the spatial distribution of electric field and electron and ion densities have been obtained by solving Poisson's equations and the continuity equations for the charged species along the Laplacian field lines. The need to iterate for the correct value of space charge on the corona electrode has been eliminated by using the corona current distribution over the grounded plane derived by Deutsch, which predicts a cos m θ law similar to Warburg's law. Based on the results of the approximated model, a parametric study of the influence of gas pressure, the corona wire radius, and the inter-electrode wire-plate separation has been carried out. Also, the approximate solutions of the electron number density has been combined with a simplified plasma chemistry model in order to compute the ozone density generated by the corona discharge in the presence of a gas flow. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.

  17. Novel dielectric reduces corona breakdown in ac capacitors

    Science.gov (United States)

    Loehner, J. L.

    1972-01-01

    Dielectric system was developed which consists of two layers of 25-gage paper separated by one layer of 50-gage polypropylene to reduce corona breakdown in ac capacitors. System can be used in any alternating current application where constant voltage does not exceed 400 V rms. With a little research it could probably be increased to 700 to 800 V rms.

  18. Degradation Processes in Corona-Charged Electret Filter-Media

    OpenAIRE

    Warren J. Jasper, Ph.D; Roger Barker, Ph.D.; Anushree Mohan; Juan Hinestroza, Ph.D.

    2007-01-01

    The degradation of filtration performance for coronachargedelectret filter media exposed to ethyl benzenewas assessed. Nonwoven corona-charged polypropylenefiber mats were exposed to ethyl-benzene using acustom made apparatus. Evaluated scenarios includedethyl-benzene vapor and liquid exposures. The filtrationperformance was evaluated using DOP as a testaerosol to measure filtration performance. It was observedthat significant filtration degradation occurredonly when liquid ethyl benzene came...

  19. Inestabilidades electrohidrodinámicas inducidas por efecto corona

    OpenAIRE

    Vega Reyes, Francisco

    2002-01-01

    La Tesis trata del estudio de la inestabilidad "Rosetón", observada en líquidos poco conductores sometidos a descargan corona.El estudio con sta de una parte experimental y una teórica:* En el estudio experimental se describen las propiedades de la corri

  20. Energy distribution of nanoflares in the quiet solar corona

    Science.gov (United States)

    Ulyanov, Artyom

    2012-07-01

    We present a detailed statistical analysis of flare-like events in low layer of solar corona detected with TESIS instrument onboard CORONAS-PHOTON satellite in 171 {Å} during high-cadence (5 sec) time-series. The estimated thermal energies of these small events amount to 10^{23} - 10^{26} erg. According to modern classification flare-like events with such energies are usually referred to as nanoflares. The big number of registered events (above 2000) allowed us to obtain precise distributions of geometric and physical parameters of nanoflares, the most intriguing being energy distribution. Following Aschwanden et al. (2000) and other authors we approximated the calculated energy distribution with a single power law slope: N(E)dE ˜ N^{-α}dE. The power law index was derived to be α = 2.4 ± 0.2, which is very close to the value reported by Krucker & Benz (1998): α ≈ 2.3 - 2.4. The total energy input from registered events constitute about 10^4 erg \\cdot cm^{-2} \\cdot s^{-1}, which is well beyond net losses in quiet corona (3 \\cdot 10^5 erg \\cdot cm^{-2} \\cdot s^{-1}). However, the value of α > 2 indicates that nanoflares with lower energies dominate over nanoflares with bigger energies and could contribute considerably to quiet corona heating.

  1. DBD-Corona Discharge for Degradation of Toxic Gases

    Institute of Scientific and Technical Information of China (English)

    M.PACHECO-PACHECO; J.PACHECO-SOTELO; H.MORENO-SAAVEDRA; J.A.DIAZ-GOMEZ; A.MERCADO-CABRERA; M.YOUSFI

    2007-01-01

    The non-thermal plasma technology is a promising technique to treat SO2 and NOx.Chemical radicals produced with this technology can remove several pollutants at atmospheric pressure in a very short period of time simultaneously.Both theoretical and experimental study on SO2 and NOx removal,by a dielectric barrier discharge (DBD) with corona effect,is presented.

  2. Simulating halos and coronas in their atmospheric environment.

    Science.gov (United States)

    David Gedzelman, Stanley

    2008-12-01

    Models are developed that simulate the light and color of the sky and of circular halos and coronas as a function of atmospheric pressure, cloud height, width, and optical depth, solar zenith angle, aerosol concentration and size, and ozone content. Halos, coronas, and skylight are treated as singly scattered sunbeams that are depleted in their passage through the atmosphere and cloud. Multiple scattering is included only for background cloud light. Halos produced by hexagonal crystal prisms and coronas produced by monodisperse droplets are visible for cloud optical depths in the range 0.0003 coronas can be bright only at smaller cloud optical depths and tend to be faint at their bottoms when produced in high cloud layers but can be bright at the horizon when produced by narrow cloud cells near ground level.

  3. Peculiarities of propagation of charged particles in solar corona

    Science.gov (United States)

    Morozova, E. I.; Pisarenko, N. F.; Mikryukova, N. A.; Klimenko, V. V.; Timofeev, V. E.; Shafer, Y. G.

    1985-01-01

    The influence of boundaries of the large scale unipolar magnetic regions (UMR) on the Sun upon the charged particle propagation in the solar corona and interplanetary space is investigated. Increases of the charged particle fluxes from solar flares on November 4 and 20, 1978 detected by Venera-11 and Prognoz-1 and on December 7, 1982 by Venera-13 and "GMS-2" were analyzed.

  4. Observational Signatures of Magnetic Reconnection in the Extended Corona

    Science.gov (United States)

    Savage, Sabrina; West, Matthew J.; Seaton, Daniel B.; Kobelski, Adam

    2016-01-01

    Observational signatures of reconnection have been studied extensively in the lower corona for decades, successfully providing insight into energy release mechanisms in the region above post-flare arcade loops and below 1.5 solar radii. During large eruptive events, however, energy release continues to occur well beyond the presence of reconnection signatures at these low heights. Supra-Arcade Downflows (SADs) and Supra-Arcade Downflowing Loops (SADLs) are particularly useful measures of continual reconnection in the corona as they may indicate the presence and path of retracting post-reconnection loops. SADs and SADLs have been faintly observed up to 18 hours beyond the passage of coronas mass ejections through the SOHO/LASCO field of view, but a recent event from 2014 October 14 associated with giant arches provides very clear observations of these downflows for days after the initial eruption. We report on this unique event and compare these findings with observational signatures of magnetic reconnection in the extended corona for more typical eruptions.

  5. The formation of corona reception of judo veteran competitive activity

    Directory of Open Access Journals (Sweden)

    Pakulin Serhij

    2016-04-01

    Full Text Available The study is devoted to the substantiation of the algorithm of corona reception of judo veteran competitive activity formation, each of its steps. Purposeful formation of judoka technical actions individual arsenal using the proposed algorithm (7 stages is implemented on the basis of the identification, a subsequent in-depth development and improvement of the best techniques.

  6. Toxicity of silica nanoparticles and the effect of protein corona

    DEFF Research Database (Denmark)

    Foldbjerg, Rasmus; Jespersen, Lars Vesterby; Wang, Jing;

    2010-01-01

      The cytotoxicity of silica nanoparticles (NPs) was investigated in the human lung cell line, A549. Silica NPs of different sizes (DLS size; 16-42 nm) were used to determine appropriate dose metrics whereas the effect of the NP corona was tested by coating the NPs with bovine serum albumin (BSA...

  7. Observational Signatures of Magnetic Reconnection in the Extended Corona

    Science.gov (United States)

    Savage, Sabrina; West, Matthew J.; Seaton, Danial B.; Kobelski, Adam

    2016-01-01

    Observational signatures of reconnection have been studied extensively in the lower corona for decades, successfully providing insight into energy release mechanisms in the region above post-flare arcade loops and below 1.5 solar radii. During large eruptive events, however, energy release continues to occur well beyond the presence of reconnection signatures at these low heights. Supra-Arcade Downflows (SADs) and Supra-Arcade Downflowing Loops (SADLs) are particularly useful measures of continual reconnection in the corona as they may indicate the presence and path of retracting post-reconnection loops. SADs and SADLs have been faintly observed up to 18 hours beyond the passage of corona mass ejections through the SOHO/LASCO field of view, but a recent event from 2014 October 14 associated with giant arches provides very clear observations of these downflows for days after the initial eruption. We report on this unique event and compare these findings with observational signatures of magnetic reconnection in the extended corona for more typical eruptions.

  8. FK506 BINDING PROTEIN 12 DEFICIENCY IN ENDOTHELIAL AND HEMATOPOIETIC CELLS DECREASES REGULATORY T CELLS AND CAUSES HYPERTENSION

    Science.gov (United States)

    Chiasson, Valorie L.; Talreja, Deepa; Young, Kristina J.; Chatterjee, Piyali; Banes-Berceli, Amy K.; Mitchell, Brett M.

    2011-01-01

    Patients treated with the immunosuppressive drug tacrolimus (FK506), which binds FK506 Binding Protein 12 (FKBP12) then inhibits the calcium-dependent phosphatase calcineurin, exhibit decreased regulatory T cells, endothelial dysfunction, and hypertension; however the mechanisms and whether altered T cell polarization play a role are unknown. Tacrolimus treatment of mice for 1 week dose-dependently decreased CD4+/FoxP3+ (regulatory T cells) and increased CD4+/IL-17+ (T helper 17) cells in the spleen, and caused endothelial dysfunction and hypertension. To determine the mechanisms, we crossed floxed FKBP12 mice with Tie2-Cre mice to generate offspring lacking FKBP12 in endothelial and hematopoietic cells only (FKBP12EC KO). Given FKBP12’s role in inhibiting TGF-β receptor activation, Tie2-Cre-mediated deletion of FKBP12 increased TGF-β receptor activation and SMAD2/3 signaling. FKBP12EC KO mice exhibited increased vascular expression of genes and proteins related to endothelial cell activation and inflammation. Serum levels of the pro-inflammatory cytokines IL-2, IL-6, IFNγ, IL-17a, IL-21, and IL-23 were increased significantly suggesting a Th17 cell-mediated inflammatory state. Flow cytometry studies confirmed this as splenocyte levels of CD4+/IL-17+ cells were increased significantly while CD4+/FoxP3+ cells were decreased in FKBP12EC KO mice. Furthermore, spleens from FKBP12EC KO mice showed increased STAT3 activation, involved in Th17 cell induction, and decreased STAT5 activation, involved in regulatory T cell induction. FKBP12EC KO mice also exhibited endothelial dysfunction and hypertension. These data suggest that tacrolimus, through its activation of TGF-β receptors in endothelial and hematopoietic cells, may cause endothelial dysfunction and hypertension by activating endothelial cells, reducing Tregs, and increasing Th17 cell polarization and inflammation. PMID:21518963

  9. Possibilities Concerning Diagnosis of the SSP-FK Aircraft Fire Suppression System in Terms of Determination of Reasons for False Fire Alarms / Możliwości Diagnozowania Lotniczego Systemu Przeciwpożarowego SSP-FK w Aspekcie Określania Przyczyn Fałszywego Sygnalizowania Pożaru

    Directory of Open Access Journals (Sweden)

    Szelmanowski Andrzej

    2015-09-01

    Full Text Available W artykule przedstawiono wybrane wyniki prac realizowanych w Instytucie Technicznym Wojsk Lotniczych (ITWL w zakresie badań instalacji przeciwpożarowej SSP-FK stosowanej na wielu typach wojskowych statków powietrznych eksploatowanych w Siłach Zbrojnych RP. Dla określania warunków fałszywego sygnalizowania pożaru opracowano modele symulacyjne działania bloków wykonawczych SSP-FK. Badania modeli symulacyjnych wykonano w pakietach obliczeniowych Matlab-Simulink i Circuit-Maker. Wyniki tych prac zostały wykorzystane do diagnostyki instalacji SSP-FK w trakcie badania rzeczywistych przypadków fałszywego zadziałania tych urządzeń.

  10. Possibilities Concerning Diagnosis of the SSP-FK Aircraft Fire Suppression System in Terms of Determination of Reasons for False Fire Alarms / Możliwości Diagnozowania Lotniczego Systemu Przeciwpożarowego Ssp-Fk W Aspekcie Określania Przyczyn Fałszywego Sygnalizowania Pożaru

    Directory of Open Access Journals (Sweden)

    Szelmanowski Andrzej

    2014-12-01

    Full Text Available W artykule przedstawiono wybrane wyniki prac realizowanych w Instytucie Technicznym Wojsk Lotniczych (ITWL w zakresie badań instalacji przeciwpożarowej SSP-FK stosowanej na wielu typach wojskowych statków powietrznych eksploatowanych w Siłach Zbrojnych RP. Dla określania warunków fałszywego sygnalizowania pożaru opracowano modele symulacyjne działania bloków wykonawczych SSP-FK. Badania modeli symulacyjnych wykonano w pakietach obliczeniowych Matlab-Simulink i Circuit-Maker. Wyniki tych prac zostały wykorzystane do diagnostyki instalacji SSP-FK w trakcie badania rzeczywistych przypadków fałszywego zadziałania tych urządzeń.

  11. Regulation of Macrophage Recognition through the Interplay of Nanoparticle Surface Functionality and Protein Corona.

    Science.gov (United States)

    Saha, Krishnendu; Rahimi, Mehran; Yazdani, Mahdieh; Kim, Sung Tae; Moyano, Daniel F; Hou, Singyuk; Das, Ridhha; Mout, Rubul; Rezaee, Farhad; Mahmoudi, Morteza; Rotello, Vincent M

    2016-04-26

    Using a family of cationic gold nanoparticles (NPs) with similar size and charge, we demonstrate that proper surface engineering can control the nature and identity of protein corona in physiological serum conditions. The protein coronas were highly dependent on the hydrophobicity and arrangement of chemical motifs on NP surface. The NPs were uptaken in macrophages in a corona-dependent manner, predominantly through recognition of specific complement proteins in the NP corona. Taken together, this study shows that surface functionality can be used to tune the protein corona formed on NP surface, dictating the interaction of NPs with macrophages.

  12. Exploring the prominence-corona connection and its expansion into the outer corona using total solar eclipse observations

    Energy Technology Data Exchange (ETDEWEB)

    Habbal, Shadia Rifai [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Morgan, Huw [Institute of Mathematics, Physics and Computer Science, Aberystwyth University, Ceredigion, Cymru SY23 3BZ (United Kingdom); Druckmüller, Miloslav, E-mail: shadia@ifa.hawaii.edu [Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno (Czech Republic)

    2014-10-01

    Prominences constitute the most complex magnetic structures in the solar corona. The ubiquitous presence of their seemingly confined dense and cool plasma in an otherwise million-degree environment remains a puzzle. Using a decade of white light total solar eclipse observations, we show how these images reveal an intricate relationship between prominences and coronal structures both in their immediate vicinity, known as coronal cavities, and in the extended corona out to several solar radii. Observations of suspended prominences and twisted helical structures spanning several solar radii are central to these findings. The different manifestations of the prominence-corona interface that emerge from this study underscore the fundamental role played by prominences in defining and controlling the complex expansion and dynamic behavior of the solar magnetic field in the neighborhood of magnetic polarity reversal regions. This study suggests that the unraveling of prominences and the outward expansion of the helical twisted field lines linked to them could be the solar origin of twisted magnetic flux ropes detected in interplanetary space, and of the mechanism by which the Sun sheds its magnetic helicity. This work also underscores the likely role of the prominence-corona interface as a source of the slow solar wind.

  13. Corona Characteristic of Power Equipments Used in ± 1 000 kV UHV DC System

    Institute of Scientific and Technical Information of China (English)

    GU Chen; FAN Jianbin; YIN Yu; Deng Tao; Zhang Qiaogen; Wang Qingliang

    2012-01-01

    Corona performance is an important factor should be taken into consideration in power transmission project designs. Power equipments operate in various environments which will affect their corona inception voltages and thus influence the operation safety of transmission systems. In this paper, corona characteristic tests of bus bars, shielding rings, simulated eight-bundled eonductors, and insulators were carried out in areas with different altitudes up to 4 300 m. Simulation tests of environmental factors were carried out in a HVDC corona cage. Based on site tests, it is concluded that corona inception voltages of both bus bar and shielding ball increase with their height to the ground or their dimensions. The influences of water droplet, wind, icing and surface contamination on corona inception voltage were also obtained from the simulation tests. The corona inception voltage of mist is higher than that in saturated water droplets. Conductivity of precipitation has little impact on corona discharges. Corona inception voltage decrease with increasing wind speed. The influence on corona current of glaze is the biggest, and that of hard rime is more than that of soft rime. The impact of pollution material on corona discharge depends on the size of pollution particle. Test results obtained in this paper are solid reference for design of UHV DC transmission projects.

  14. 供体特异输注及FK506对同种异体小鼠心脏移植急性排斥反应的影响%Effects of Donor-Specific Transfusion and FK506 on Cardiac Allo-transplantation in Mice during Acute Rejection

    Institute of Scientific and Technical Information of China (English)

    何强; 杜峻峰; 张洪伟; 王为忠

    2008-01-01

    目的:探讨供体特异输注(donor-specific transfusion,DST)及不同剂量FK506对同种异体小鼠心脏移植的影响.方法:应用显微外科技术制作颈部移植心脏急性排斥反应小鼠模型,将移植受体小鼠分为4组:对照组(单纯移植组,未加DST),DST+移植组,DST+移植+FK506(2meg/(kg·d))组,DST+移植+FK506(0.3mg/(kg·d))组,比较各组移植心脏生存时间,心肌病理改变及外周血血清细胞因子水平:血清IL-2,IL-4,IL-10和IFN-γ水平.结果:术前1天应用DST与连续应用较小剂量FK506可显著延长移植物存活.术后第七天病理检查发现联合应用DST和FK506的两组移植物急性免疫排斥反应明显比其他两组减轻.血清中IL-2和IFN-γ水平在联合应用DST和FK506的两组明显低于其它两组,IL-4和IL-10水平在联合应用DST和FK506的两组高于对照组和DST+移植组.结论:术前DST及持续应用较小剂量FK506可有效抑制同种异体小鼠颈部心脏移植术后急性排斥反应,显著延长移植物的生存时间.

  15. The biomolecular corona of nanoparticles in circulating biological media

    Science.gov (United States)

    Pozzi, D.; Caracciolo, G.; Digiacomo, L.; Colapicchioni, V.; Palchetti, S.; Capriotti, A. L.; Cavaliere, C.; Zenezini Chiozzi, R.; Puglisi, A.; Laganà, A.

    2015-08-01

    When nanoparticles come into contact with biological media, they are covered by a biomolecular `corona', which confers a new identity to the particles. In all the studies reported so far nanoparticles are incubated with isolated plasma or serum that are used as a model for protein adsorption. Anyway, bodily fluids are dynamic in nature so the question arises on whether the incubation protocol, i.e. dynamic vs. static incubation, could affect the composition and structure of the biomolecular corona. Here we let multicomponent liposomes interact with fetal bovine serum (FBS) both statically and dynamically, i.e. in contact with circulating FBS (~40 cm s-1). The structure and composition of the liposome-protein corona, as determined by dynamic light scattering, electrophoretic light scattering and liquid chromatography tandem mass spectrometry, were found to be dependent on the incubation protocol. Specifically, following dynamic exposure to FBS, multicomponent liposomes were less enriched in complement proteins and appreciably more enriched in apolipoproteins and acute phase proteins (e.g. alpha-1-antitrypsin and inter-alpha-trypsin inhibitor heavy chain H3) that are involved in relevant interactions between nanoparticles and living systems. Supported by our results, we speculate that efficient predictive modeling of nanoparticle behavior in vivo will require accurate knowledge of nanoparticle-specific protein fingerprints in circulating biological media.When nanoparticles come into contact with biological media, they are covered by a biomolecular `corona', which confers a new identity to the particles. In all the studies reported so far nanoparticles are incubated with isolated plasma or serum that are used as a model for protein adsorption. Anyway, bodily fluids are dynamic in nature so the question arises on whether the incubation protocol, i.e. dynamic vs. static incubation, could affect the composition and structure of the biomolecular corona. Here we let

  16. Tacrolimus (FK506 suppresses TREM-1 expression at an early but not at a late stage in a murine model of fungal keratitis.

    Directory of Open Access Journals (Sweden)

    Weilan Huang

    Full Text Available To investigate the efficacy and mechanism of tacrolimus(FK506, which is a novel macrolide immunosuppressant, in inhibiting triggering receptor expressed on myeloid cells-1 (TREM-1 expression in a murine keratitis model induced by Aspergillus fumigatus.TREM-1 was detected in 11 fungus-infected human corneas by quantitative real-time PCR (qRT-PCR. RAW264.7 macrophages were divided into four groups, which received treatment with zymosan (100 µg/ml, zymosan (100 µg/ml + mTREM-1/Fc protein (1 µg/ml, or zymosan (100 µg/ml + FK506 (20 µM or negative-control treatment. After this treatment, the expression of TREM-1, interleukin-1β (IL-1β and tumor necrosis factor α (TNFα was assayed using qRT-PCR and ELISA. The mouse model of fungal keratitis was created by intrastromal injection with Aspergillus fumigatus, and the mice were divided into 2 groups: group A received vehicle eye drops 4 times each day, and group B received 4 doses of FK506 eye drops each day. Corneal damage was evaluated by clinical scoring and histologic examination,and myeloperoxidase (MPO protein levels were also detected by ELISA. The expression of TREM-1, IL-1β and TNFα was then determined at different time points using qRT-PCR and ELISA.TREM-1 expression dramatically increased in the human corneas with fungal keratitis. In contrast, FK506 reduced the expression of TREM-1, IL-1β and TNFα in RAW264.7 macrophages stimulated with zymosan. In the mouse model, at day 1 post-infection, the corneal score of the FK506-treated group was lower than that of the control, and polymorphonuclear neutrophil (PMN infiltration was diminished. TREM-1, IL-1β and TNFα expression was significantly reduced at the same time point. However, the statistically significant differences in cytokine expression, clinical scores and infiltration disappeared at 5 days post-infection.FK506 may inhibit the inflammation induced by fungi and alleviate the severity of corneal damage at an early stage of

  17. Monitoring of the Enzymatic Degradation of Protein Corona and Evaluating the Accompanying Cytotoxicity of Nanoparticles.

    Science.gov (United States)

    Ma, Zhifang; Bai, Jing; Jiang, Xiue

    2015-08-19

    Established nanobio interactions face the challenge that the formation of nanoparticle-protein corona complexes shields the inherent properties of the nanoparticles and alters the manner of the interactions between nanoparticles and biological systems. Therefore, many studies have focused on protein corona-mediated nanoparticle binding, internalization, and intracellular transportation. However, there are a few studies to pay attention to if the corona encounters degradation after internalization and how the degradation of the protein corona affects cytotoxicity. To fill this gap, we prepared three types of off/on complexes based on gold nanoparticles (Au NPs) and dye-labeled serum proteins and studied the extracellular and intracellular proteolytic processes of protein coronas as well as their accompanying effects on cytotoxicity through multiple evaluation mechanisms, including cell viability, adenosine triphosphate (ATP) content, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS). The proteolytic process was confirmed by recovery of the fluorescence of the dye-labeled protein molecules that was initially quenched by Au NPs. Our results indicate that the degradation rate of protein corona is dependent on the type of the protein based on systematical evaluation of the extracellular and intracellular degradation processes of the protein coronas formed by human serum albumin (HSA), γ-globulin (HGG), and serum fibrinogen (HSF). Degradation is the fastest for HSA corona and the slowest for HSF corona. Notably, we also find that the Au NP-HSA corona complex induces lower cell viability, slower ATP production, lower MMP, and higher ROS levels. The cytotoxicity of the nanoparticle-protein corona complex may be associated with the protein corona degradation process. All of these results will enrich the database of cytotoxicity induced by nanomaterial-protein corona complexes.

  18. Pulsed Corona Discharges and Their Applications in Toxic VOCs Abatement

    Institute of Scientific and Technical Information of China (English)

    MuhammadArifMalik; SalmanAkbarMalik

    1999-01-01

    plasma processes are among the emerging technologies for volatile organic compounds (VOCs) sbatoment. Both thermal plasmas and non-equil[brimn plasmas (cold plasmas) are being developed for VOCs clesnup. Particularly, pulsed corona discharges offer several edvantages over conventional VOCs abatement tochniqvee, To optimize the existing technology and to developit further, there is need to understand the mechanlsms involved in plasma chemical reacticms, Furthermore, it is strongly desirable to be able to predict the behavior of new VOCs in non-equillbrlum plasma enviromuent from the data known for a few representative oompounds, Pulsed corona discharge technique is introduced here with dtafion of refevant literature, Fundamental principfes,useful for predicting the VOCs' decomposition behavior, have been worked out from the published literature. Latest developments in the area, targeted to minimize the enersy losses, improve the VOCs destruction efficiency and reduce the generation of unwanted organic and inorganic by-products, are presented.

  19. Measuring the IR solar corona during the 2017 eclipse

    Science.gov (United States)

    Bryans, Paul; Hannigan, James; Philip, Judge; Larson, Brandon; Sewell, Scott; McIntire, Lauren

    2016-05-01

    On 21 August 2017 a total solar eclipse will pass across the continental United States, offering a unique opportunity to conduct scientific research of the solar atmosphere. With the light from the Sun eclipsed, the solar corona becomes visible in a way not possible when swamped by the light from the photosphere. The infrared (IR) spectrum of the corona, in particular, is predicted to contain some of the most magnetically sensitive spectral lines. However, no comprehensive survey of this spectral range has been carried out to date. Here, we describe a Fourier Transform Spectrometer, currently under construction at NCAR, to measure the IR spectrum from 2 to 12 microns. We will discuss the operation of the experiment, which will be deployed along the path of totality in Wyoming, and the scientific results we hope to obtain.

  20. Imaging the structure of the low K-corona

    Science.gov (United States)

    Kim, I. S.; Nasonova, L. P.; Lisin, D. V.; Popov, V. V.; Krusanova, N. L.

    2017-01-01

    The first 2-D distributions of the polarization angle and of the relative color index for the K-corona of 29 March 2006 are presented. The distributions illustrate the efficiency of the total solar eclipse approach for high-precision measurements of the K-corona continuum in the range planets are discussed. Calculations of the eclipse magnitude m are carried out to show ideal conditions for total solar eclipse observations in space from Lagrange point L2 for Mars (m ≈ 1.025). The illumination in Mars' shadow is estimated to equal 5.6 × 10-11 for the wavelength of 550 nm. No internal or external occulting coronagraphs are needed. Partial solar eclipses with m > 0.91 can be observed from Lagrange points L2 for Mercury, Venus, and Earth.

  1. Intermittent heating of the solar corona by MHD turbulence

    Directory of Open Access Journals (Sweden)

    É. Buchlin

    2007-10-01

    Full Text Available As the dissipation mechanisms considered for the heating of the solar corona would be sufficiently efficient only in the presence of small scales, turbulence is thought to be a key player in the coronal heating processes: it allows indeed to transfer energy from the large scales to these small scales. While Direct numerical simulations which have been performed to investigate the properties of magnetohydrodynamic turbulence in the corona have provided interesting results, they are limited to small Reynolds numbers. We present here a model of coronal loop turbulence involving shell-models and Alfvén waves propagation, allowing the much faster computation of spectra and turbulence statistics at higher Reynolds numbers. We also present first results of the forward-modelling of spectroscopic observables in the UV.

  2. Detailed characteristics of intermittent current pulses due to positive corona

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: liuyangwuh520@sina.com; Cui, Xiang; Lu, Tiebing; Wang, Zhenguo; Li, Xuebao; Xiang, Yu; Wang, Xiaobo [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China)

    2014-08-15

    In order to get detailed characteristics of intermittent current pulses due to positive corona such as the repetition rate of burst-pulse trains, the peak value ratio of the primary pulse to the secondary pulse, the number of pulses per burst, and the interval of the secondary pulses, a systematic study was carried out in a coaxial conductor-cylinder electrode system with the conductor electrode being set with a discharge point. Empirical formulae for the number of pulses per burst and the interval of the secondary pulses are first presented. A theoretical model based on the motion of the space-charge clouds is proposed. Analysis with the model gives explanations to the experimental results and reveals some new insights into the physical mechanism of positive intermittent corona.

  3. Conversion of Methane to Hydrogen via Pulsed Corona Discharge

    Institute of Scientific and Technical Information of China (English)

    Lekha Nath Mishra; Kanetoshi Shibata; Hiroaki Ito; Noboru Yugami; Yasushi Nishida

    2004-01-01

    Experiments are performed to develop a pulsed corona discharge system for the conversion of methane to hydrogen at atmospheric pressure (≌760 Tort) without using a catalyst. The corona discharge was energized by 10-12 μs wide voltage pulses (≤7 kV) at a repetition rate of about 1.0-1.5 kHz. The residual gases were characterized by mass spectrometry. The conversion of methane is as high as 50.8%producing the 70% yield of hydrogen. The influences of argon on the discharge of methane were studied.This result could be useful for the mass production of hydrogen in both academic and industrial point of view.

  4. Acoustic field effects on a negative corona discharge

    Science.gov (United States)

    Bálek, R.; Červenka, M.; Pekárek, S.

    2014-06-01

    For a negative corona discharge under atmospheric pressure in different regimes, we investigated the effects of an acoustic field both on its electrical parameters and on the change in its visual appearance. We found that the application of an acoustic field on the true corona discharge, for particular currents, decreases the discharge voltage. The application of an acoustic field on the discharge in the filamentary streamer regime substantially extends the range of currents for which the discharge voltage remains more or less constant, i.e. it allows a substantial increase in the power delivered to the discharge. The application of an acoustic field on the discharge causes the discharge to spread within the discharge chamber and consequently, a highly reactive non-equilibrium plasma is created throughout the inter-electrode space. Finally, our experimental apparatus radiates almost no acoustic energy from the discharge chamber.

  5. The Structure and Dynamics of the Solar Corona

    Science.gov (United States)

    Mikic, Zoran

    2000-01-01

    This report covers technical progress during the third year of the NASA Space Physics Theory contract "The Structure and Dynamics of the Solar Corona," between NASA and Science Applications International Corporation, and covers the period June 16, 1998 to August 15, 1999. This is also the final report for this contract. Under this contract SAIC, the University of California, Irvine (UCI), and the Jet Propulsion Laboratory (JPL), have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model. During the three-year duration of this contract we have published 49 articles in the scientific literature. These publications are listed in Section 3 of this report. In the Appendix we have attached reprints of selected articles. We summarize our progress during the third year of the contract. Full descriptions of our work can be found in the cited publications, a few of which are attached to this report.

  6. On the Size of Structures in the Solar Corona

    CERN Document Server

    DeForest, C E

    2006-01-01

    Fine-scale structure in the corona appears not to be well resolved by current imaging instruments. Assuming this to be true offers a simple geometric explanation for several current puzzles in coronal physics, including: the apparent uniform cross-section of bright threadlike structures in the corona; the low EUV contrast (long apparent scale height) between the top and bottom of active region loops; the inconsistency between loop densities derived by spectral and photometric means; the rapid time scale of active region loop evolution; and the presence of tall, cool, FUV-bright loops in active regions and post-flare arcades. Treating coronal loops as a mixture of diffuse background and very dense, unresolved filamentary structures address these problems with a combination of high plasma density within the structures, shortening the radiative time and greatly increasing the emissivity of the structures, and geometric effects that attenuate the apparent brightness of the feature at low altitudes. Using the low-...

  7. Heating of the Solar Corona and its Loops

    Science.gov (United States)

    Klimchuk, James A.

    2009-01-01

    At several million degrees, the solar corona is more than two orders of magnitude hotter than the underlying solar surface. The reason for these extreme conditions has been a puzzle for decades and is considered one of the fundamental problems in astrophysics. Much of the coronal plasma is organized by the magnetic field into arch-like structures called loops. Recent observational and theoretical advances have led to great progress in understanding the nature of these loops. In particular, we now believe they are bundles of unresolved magnetic strands that are heated by storms of impulsive energy bursts called nanoflares. Turbulent convection at the solar surface shuffles the footpoints of the strands and causes them to become tangled. A nanoflare occurs when the magnetic stresses reach a critical threshold, probably by way of a mechanism called the secondary instability. I will describe our current state of knowledge concerning the corona, its loops, and how they are heated.

  8. Effects of Fieldline Topology on Energy Propagation in the Corona

    CERN Document Server

    Candelaresi, Simon; Hornig, Gunnar

    2016-01-01

    We study the effect of photospheric footpoint motions on magnetic field structures containing magnetic nulls. The footpoint motions are prescribed on the photospheric boundary as a velocity field which entangles the magnetic field. We investigate the propagation of the injected energy, the conversion of energy, emergence of current layers and other consequences of the non-trivial magnetic field topology in this situation. These boundary motions lead initially to an increase in magnetic and kinetic energy. Following this, the energy input from the photosphere is partially dissipated and partially transported out of the domain through the Poynting flux. The presence of separatrix layers and magnetic null-points fundamentally alters the propagation behavior of disturbances from the photosphere into the corona. Depending on the field line topology close to the photosphere, the energy is either trapped or free to propagate into the corona.

  9. Air trichloroethylene oxidation in a corona plasma-catalytic reactor

    Science.gov (United States)

    Masoomi-Godarzi, S.; Ranji-Burachaloo, H.; Khodadadi, A. A.; Vesali-Naseh, M.; Mortazavi, Y.

    2014-08-01

    The oxidative decomposition of trichloroethylene (TCE; 300 ppm) by non-thermal corona plasma was investigated in dry air at atmospheric pressure and room temperature, both in the absence and presence of catalysts including MnOx, CoOx. The catalysts were synthesized by a co-precipitation method. The morphology and structure of the catalysts were characterized by BET surface area measurement and Fourier Transform Infrared (FTIR) methods. Decomposition of TCE and distribution of products were evaluated by a gas chromatograph (GC) and an FTIR. In the absence of the catalyst, TCE removal is increased with increases in the applied voltage and current intensity. Higher TCE removal and CO2 selectivity is observed in presence of the corona and catalysts, as compared to those with the plasma alone. The results show that MnOx and CoOx catalysts can dissociate the in-plasma produced ozone to oxygen radicals, which enhances the TCE decomposition.

  10. Improvement of FK506 Production in the High-Yielding Strain Streptomyces sp. RM7011 by Engineering the Supply of Allylmalonyl-CoA Through a Combination of Genetic and Chemical Approach.

    Science.gov (United States)

    Mo, SangJoon; Lee, Sung-Kwon; Jin, Ying-Yu; Suh, Joo-Won

    2016-02-01

    FK506, a widely used immunosuppressant, is a 23-membered polyketide macrolide that is produced by several Streptomyces species. FK506 high-yielding strain Streptomyces sp. RM7011 was developed from the discovered Streptomyces sp. KCCM 11116P by random mutagenesis in our previous study. The results of transcript expression analysis showed that the transcription levels of tcsA, B, C, and D were increased in Streptomyces sp. RM7011 by 2.1-, 3.1-, 3.3-, and 4.1- fold, respectively, compared with Streptomyces sp. KCCM 11116P. The overexpression of tcsABCD genes in Streptomyces sp. RM7011 gave rise to approximately 2.5-fold (238.1 μg/ml) increase in the level of FK506 production compared with that of Streptomyces sp. RM7011. When vinyl pentanoate was added into the culture broth of Streptomyces sp. RM7011, the level of FK506 production was approximately 2.2-fold (207.7 μg/ml) higher than that of the unsupplemented fermentation. Furthermore, supplementing the culture broth of Streptomyces sp. RM7011 expressing tcsABCD genes with vinyl pentanoate resulted in an additional 1.7-fold improvement in the FK506 titer (498.1 μg/ml) compared with that observed under nonsupplemented condition. Overall, the level of FK506 production was increased approximately 5.2-fold by engineering the supply of allylmalonyl-CoA in the high-yielding strain Streptomyces sp. RM7011, using a combination of overexpressing tcsABCD genes and adding vinyl pentanoate, as compared with Streptomyces sp. RM7011 (95.3 μg/ml). Moreover, among the three precursors analyzed, pentanoate was the most effective precursor, supporting the highest titer of FK506 in the FK506 high-yielding strain Streptomyces sp. RM7011.

  11. Mass and Energy Transfer Between the Solar Photosphere and Corona

    Science.gov (United States)

    Peter, H.

    2015-12-01

    The problem of chromospheric and coronal heating is also a problem of mass supply to the corona. On average we see redshifts at transition region temperatures of the order of 10 km/s. If interpreted as downflows, this would quickly empty the corona, and fresh material has to be transported into the corona. Several models have been proposed to understand this mass cycle between the different atmospheric layers. However, as of yet all these proposals have serious shortcomings. On the observational side open questions remain, too. With the new IRIS mission we can observe the transition region at unprecedented spatial and spectral resolution, but the observational results are still puzzling. In particular the finding that the spatial distribution of line widths and Doppler shifts do not change with increasing resolution is against physical intuition. This shows that even with IRIS we still have significant velocity gradients along the line-of-sight, indicating that shocks might play a significant role. Likewise the temporal evolution might be a key for our understanding of the mass cycle. It might well be that the filling and draining of hot plasma occurs on significantly different time scales, which might be part of the difficulty to arrive at a conclusive observational picture. Considering the progress made for the quiet Sun, it seems clear that the processes responsible for the mass exchange are not resolved (yet). Therefore one might wonder to what extent one could use larger and resolved individual events in more active parts of the Sun to understand the details of the mass transport. In particular a common understanding of reconnection events such as Ellerman bombs in the photosphere, explosive events in the transition region and the recently discovered IRIS bombs in-between might provide the key to better understand the mass cycle throughout the atmospheric layers from the photosphere to the corona.

  12. Properties and Distribution of Current Sheets in Accretion Disk Coronae

    Science.gov (United States)

    Salvesen, Greg; Begelman, M. C.; Simon, J. B.; Beckwith, K.

    2013-04-01

    Theoretical models involving the interplay of a geometrically thin, optically thick accretion disk embedded in an extended coronal atmosphere may describe black hole X-ray binaries across all spectral states. Buoyant magnetic field generated in the accretion disk is continuously supplied to the corona by a dynamo process driven by the magnetorotational instability. This rising field leads to the formation of a magnetic pressure-dominated, low-density, geometrically thick corona where substantial accretion energy is dissipated, likely by collisionless magnetic reconnection, perhaps even generating outflows. Despite the potential importance of magnetic reconnection in shaping the energetics and kinematics of the corona, studies of multiple reconnection sites in a large volume are currently prohibited by the computational expense required to properly treat the microphysical nature of reconnection. Under the assumption that coronal structure is determined by ideal magnetohydrodynamics, we analyze local simulations of accretion disks (i.e., shearing boxes) performed with the ATHENA code, where the spatial domains are extended to capture 'mesoscale' structures that are dynamically important in accretion disk evolution. We employ a location routine to identify zones of enhanced current density, which trace likely sites of magnetic reconnection. We describe the positions, orientations, sizes, shapes, strengths, and kinematics of these regions and correlate them with the spatial distribution of numerical dissipation. Statistical distributions of these various properties of current density zones are presented to determine the heights within the corona that contribute most to the dissipation rate, the flow properties associated with reconnection sites, and representative parameters for future large volume reconnection simulations.

  13. Uso de coronas sistema cad-cam en implantes osteointegrados

    Directory of Open Access Journals (Sweden)

    Dr. R. Daniel Bacigalupe

    2014-01-01

    En este trabajo de investigación planteamos la posibilidad de utilizar en forma usual cerámica feldespática pre-sinterizada en presentación de cubo y manejada por sistema asistido por computador (CEREC, elaborándose coronas de forma inmediata sobre pilares metálicos maquinados en implantes oseointegrados. Evaluando si este material es capaz de resistir la fuerza masticatoria.

  14. Estimation of winding insulation resistance to the corona discharges

    Science.gov (United States)

    Leonov, A.; Red'ko, V.; Soldatenko, E.

    2014-10-01

    This article presents test results of enameled winding wires, characterizing an insulation electrical and mechanical strength. Standard and original test methods were used. Note that existing standard test methods do not estimate enamel insulation resistance to the electrical loads under winding operation of variable-speed drive. We show that estimation of wire corona resistance can be done by high frequency electrical impulse testing. Wire insulation plays the main role of reliability of insulation system.

  15. X-ray coronae in simulations of disc galaxy formation

    Science.gov (United States)

    Crain, Robert A.; McCarthy, Ian G.; Frenk, Carlos S.; Theuns, Tom; Schaye, Joop

    2010-09-01

    The existence of X-ray luminous gaseous coronae around massive disc galaxies is a long-standing prediction of galaxy formation theory in the cold dark matter cosmogony. This prediction has garnered little observational support, with non-detections commonplace and detections for only a relatively small number of galaxies which are much less luminous than expected. We investigate the coronal properties of a large sample of bright, disc-dominated galaxies extracted from the GIMIC suite of cosmological hydrodynamic simulations recently presented by Crain et al. Remarkably, the simulations reproduce the observed scalings of X-ray luminosity with K-band luminosity and star formation rate (SFR) and, when account is taken of the density structure of the halo, with disc rotation velocity as well. Most of the star formation in the simulated galaxies (which have realistic stellar mass fractions) is fuelled by gas cooling from a quasi-hydrostatic hot corona. However, these coronae are more diffuse, and of a lower luminosity, than predicted by the analytic models of White & Frenk because of a substantial increase in entropy at z ~ 1-3. Both the removal of low entropy gas by star formation and energy injection from supernovae contribute to this increase in entropy, but the latter is dominant for halo masses M200 <~ 1012.5Msolar. Only a small fraction of the mass of the hot gas is outflowing as a wind but, because of its high density and metallicity, it contributes disproportionally to the X-ray emission. The bulk of the X-ray emission, however, comes from the diffuse quasi-hydrostatic corona which supplies the fuel for ongoing star formation in discs today. Future deep X-ray observations with high spectral resolution (e.g. with NeXT/ASTRO-H or IXO) should be able to map the velocity structure of the hot gas and test this fundamental prediction of current galaxy formation theory.

  16. Kinetic Physics of the Solar Corona and Solar Wind

    Directory of Open Access Journals (Sweden)

    Marsch Eckart

    2006-07-01

    Full Text Available Kinetic plasma physics of the solar corona and solar wind are reviewed with emphasis on the theoretical understanding of the in situ measurements of solar wind particles and waves, as well as on the remote-sensing observations of the solar corona made by means of ultraviolet spectroscopy and imaging. In order to explain coronal and interplanetary heating, the microphysics of the dissipation of various forms of mechanical, electric and magnetic energy at small scales (e.g., contained in plasma waves, turbulences or non-uniform flows must be addressed. We therefore scrutinise the basic assumptions underlying the classical transport theory and the related collisional heating rates, and also describe alternatives associated with wave-particle interactions. We elucidate the kinetic aspects of heating the solar corona and interplanetary plasma through Landau- and cyclotron-resonant damping of plasma waves, and analyse in detail wave absorption and micro instabilities. Important aspects (virtues and limitations of fluid models, either single- and multi-species or magnetohydrodynamic and multi-moment models, for coronal heating and solar wind acceleration are critically discussed. Also, kinetic model results which were recently obtained by numerically solving the Vlasov–Boltzmann equation in a coronal funnel and hole are presented. Promising areas and perspectives for future research are outlined finally.

  17. The 2008 August 1 Eclipse Solar-Minimum Corona Unraveled

    CERN Document Server

    Pasachoff, Jay M; Druckmuller, Miloslav; Aniol, Peter; Saniga, Metod; Minarovjech, Milan

    2009-01-01

    We discuss results stemming from observations of the white-light and [Fe XIV] emission corona during the total eclipse of the Sun of 2008 August 1, in Mongolia (Altaj region) and in Russia (Akademgorodok, Novosibirsk, Siberia). Corresponding to the current extreme solar minimum, the white-light corona, visible up to 20 solar radii, was of a transient type with well-pronounced helmet streamers situated above a chain of prominences at position angles 48, 130, 241 and 322 degrees. A variety of coronal holes, filled with a number of thin polar plumes, were seen around the poles. Furthering an original method of image processing, stars up to 12 magnitude, a Kreutz-group comet (C/2008 O1), and a coronal mass ejection (CME) were also detected, with the smallest resolvable structures being of, and at some places even less than, 1 arcsec. Differences, presumably motions, in the corona and prominences are seen even with the 19-min time difference between our sites. In addition to the high-resolution coronal images, whi...

  18. Hydrogen production from dimethyl ether using corona discharge plasma

    Science.gov (United States)

    Zou, Ji-Jun; Zhang, Yue-Ping; Liu, Chang-Jun

    Dimethyl ether (DME), with its non-toxic character, high H/C ratio and high-energy volumetric density, is an ideal resource for hydrogen production. In this work, hydrogen production from the decomposition of DME using corona discharge has been studied. The corona discharge plasma decomposition was conducted at ambient conditions. The effects of dilution gas (argon), flow rate, frequency and waveforms on the DME decomposition were investigated. The addition of dilution gas can significantly increase the hydrogen production rate. The highest hydrogen production rate with the lowest energy consumption presents at the flow rate of 27.5 Nml min -1. AC voltage is more favored than DC voltage for the production of hydrogen with less energy input. The optimal frequency is 2.0 kHz. The hydrogen production rate is also affected by the input waveform and decreases as following: sinusoid triangular > sinusoid > ramp > square, whereas the sinusoid waveform shows the highest energy efficiency. The corona discharge decomposition of DME is leading to a simple, easy and convenient hydrogen production with no needs of catalyst and external heating.

  19. Model of Ozone Production in the DC Corona Discharge

    Science.gov (United States)

    Chen, Junhong; Davidson, Jane

    2002-10-01

    A comprehensive numerical model of ozone production in clean, dry air by DC corona discharges is presented. This model combines a first-principle corona plasma model with a chemistry and 2-D transport model to obtain the distributions of ozone and other gaseous products in the neighborhood of a corona discharge wire. Electron number density distribution is obtained by solving the continuity equations for electrons and ions and the simplified Maxwell's equation. The non-Maxwellian electron energy distribution is solved from the Boltzmann equation. The chemical kinetics of ozone formation and destruction are based on recent atmospheric chemistry models taking into account the contributions of excited molecules. The transport model includes the conservation equations for total mass, momentum, energy and the mass of individual species and is solved using FLUENT. The predicted ozone production rate agrees well with experimental data. Excited molecules contribute more than 80 percent of the total ozone produced. The effects of discharge polarity, current, wire radius, air temperature, and air velocity (residence time) on the production of ozone are discussed.

  20. Vortex focusing of ions produced in corona discharge.

    Science.gov (United States)

    Kolomiets, Yuri N; Pervukhin, Viktor V

    2013-06-15

    Completeness of the ion transportation into an analytical path defines the efficiency of ionization analysis techniques. This is of particular importance for atmospheric pressure ionization sources like corona discharge, electrospray, ionization with radioactive ((3)H, (63)Ni) isotopes that produce nonuniform spatial distribution of sample ions. The available methods of sample ion focusing are either efficient at reduced pressure (~1Torr) or feature high sample losses. This paper deals with experimental research into atmospheric pressure focusing of unipolar (positive) ions using a highly swirled air stream with a well-defined vortex core. Effects of electrical fields from corona needle and inlet capillary of mass spectrometer on collection efficiency is considered. We used a corona discharge to produce an ionized unipolar sample. It is shown experimentally that with an electrical field barrier efficient transportation and focusing of an ionized sample are possible only when a metal plate restricting the stream and provided with an opening covered with a grid is used. This gives a five-fold increase of the transportation efficiency. It is shown that the electric field barrier in the vortex sampling region reduces the efficiency of remote ionized sample transportation two times. The difference in the efficiency of light ion focusing observed may be explained by a high mobility and a significant effect of the electric field barrier upon them. It is possible to conclude based on the experimental data that the presence of the field barrier narrows considerably (more than by one and half) the region of the vortex sample ion focusing.

  1. Direct Measurements of Magnetic Twist in the Solar Corona

    CERN Document Server

    Malanushenko, A; Longcope, D W

    2012-01-01

    In the present work we study evolution of magnetic helicity in the solar corona. We compare the rate of change of a quantity related to the magnetic helicity in the corona to the flux of magnetic helicity through the photosphere and find that the two rates are similar. This gives observational evidence that helicity flux across the photosphere is indeed what drives helicity changes in solar corona during emergence. For the purposes of estimating coronal helicity we neither assume a strictly linear force-free field, nor attempt to construct a non-linear force-free field. For each coronal loop evident in Extreme Ultraviolet (EUV) we find a best-matching line of a linear force-free field and allow the twist parameter alpha to be different for each line. This method was introduced and its applicability was discussed in Malanushenko et. al. (2009). The object of the study is emerging and rapidly rotating AR 9004 over about 80 hours. As a proxy for coronal helicity we use the quantity averaged over many reconstruc...

  2. Joule heating and anomalous resistivity in the solar corona

    Directory of Open Access Journals (Sweden)

    S. R. Spangler

    2009-06-01

    Full Text Available Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as 2.5×109 Amperes (Spangler, 2007. These estimates of currents are used to develop a model for Joule heating in the corona. It is assumed that the currents are concentrated in thin current sheets, as suggested by theories of two dimensional magnetohydrodynamic turbulence. The Spitzer result for the resistivity is adopted as a lower limit to the true resistivity. The calculated volumetric heating rate is compared with an independent theoretical estimate by Cranmer et al. (2007. This latter estimate accounts for the dynamic and thermodynamic properties of the corona at a heliocentric distance of several solar radii. Our calculated Joule heating rate is less than the Cranmer et al estimate by at least a factor of 3×105. The currents inferred from the observations of Spangler (2007 are not relevant to coronal heating unless the true resistivity is enormously increased relative to the Spitzer value. However, the same model for turbulent current sheets used to calculate the heating rate also gives an electron drift speed which can be comparable to the electron thermal speed, and larger than the ion acoustic speed. It is therefore possible that the coronal current sheets are unstable to current-driven instabilities which produce high levels of waves, enhance the resistivity and thus the heating rate.

  3. The Magnetic Field of the Solar Corona from Pulsar Observations

    CERN Document Server

    Ord, S M; Sarkissian, J

    2007-01-01

    We present a novel experiment with the capacity to independently measure both the electron density and the magnetic field of the solar corona. We achieve this through measurement of the excess Faraday rotation due to propagation of the polarised emission from a number of pulsars through the magnetic field of the solar corona. This method yields independent measures of the integrated electron density, via dispersion of the pulsed signal and the magnetic field, via the amount of Faraday rotation. In principle this allows the determination of the integrated magnetic field through the solar corona along many lines of sight without any assumptions regarding the electron density distribution. We present a detection of an increase in the rotation measure of the pulsar J1801$-$2304 of approximately 160 \\rad at an elongation of 0.95$^\\circ$ from the centre of the solar disk. This corresponds to a lower limit of the magnetic field strength along this line of sight of $> 393\\mu\\mathrm{G}$. The lack of precision in the i...

  4. Numerical Simulations of Helicity Condensation in the Solar Corona

    Science.gov (United States)

    Zhao, L.; DeVore, C. R.; Antiochos, S. K.; Zurbuchen, T. H.

    2015-01-01

    The helicity condensation model has been proposed by Antiochos (2013) to explain the observed smoothness of coronal loops and the observed buildup of magnetic shear at filament channels. The basic hypothesis of the model is that magnetic reconnection in the corona causes the magnetic stress injected by photospheric motions to collect only at those special locations where prominences form. In this work we present the first detailed quantitative MHD simulations of the reconnection evolution proposed by the helicity condensation model. We use the well-known ansatz of modeling the closed corona as an initially uniform field between two horizontal photospheric plates. The system is driven by applying photospheric rotational flows that inject magnetic helicity into the system. The flows are confined to a finite region on the photosphere so as to mimic the finite flux system of, for example, a bipolar active region. The calculations demonstrate that, contrary to common belief, coronal loops having opposite helicity do not reconnect, whereas loops having the same sense of helicity do reconnect. Furthermore, we find that for a given amount of helicity injected into the corona, the evolution of the magnetic shear is insensitive to whether the pattern of driving photospheric motions is fixed or quasi-random. In all cases, the shear propagates via reconnection to the boundary of the flow region while the total magnetic helicity is conserved, as predicted by the model. We discuss the implications of our results for solar observations and for future, more realistic simulations of the helicity condensation process.

  5. Intentional formation of a protein corona on nanoparticles: Serum concentration affects protein corona mass, surface charge, and nanoparticle-cell interaction.

    Science.gov (United States)

    Gräfe, Christine; Weidner, Andreas; Lühe, Moritz V D; Bergemann, Christian; Schacher, Felix H; Clement, Joachim H; Dutz, Silvio

    2016-06-01

    The protein corona, which immediately is formed after contact of nanoparticles and biological systems, plays a crucial role for the biological fate of nanoparticles. In the here presented study we describe a strategy to control the amount of corona proteins which bind on particle surface and the impact of such a protein corona on particle-cell interactions. For corona formation, polyethyleneimine (PEI) coated magnetic nanoparticles (MNP) were incubated in a medium consisting of fetal calf serum (FCS) and cell culture medium. To modulate the amount of proteins bind to particles, the composition of the incubation medium was varied with regard to the FCS content. The protein corona mass was estimated and the size distribution of the participating proteins was determined by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Additionally, the zeta potential of incubated particles was measured. Human blood-brain barrier-representing cell line HBMEC was used for in vitro incubation experiments. To investigate the consequences of the FCS dependent protein corona formation on the interaction of MNP and cells flow cytometry and laser scanning microscopy were used. Zeta potential as well as SDS-PAGE clearly reveal an increase in the amount of corona proteins on MNP with increasing amount of FCS in incubation medium. For MNP incubated with lower FCS concentrations especially medium-sized proteins of molecular weights between 30kDa and 100kDa could be found within the protein corona, whereas for MNP incubated within higher FCS concentrations the fraction of corona proteins of 30kDa and less increased. The presence of the protein corona reduces the interaction of PEI-coated MNP with HBMEC cells within a 30min-incubation.

  6. Two crystal structures of the FK506-binding domain of Plasmodium falciparum FKBP35 in complex with rapamycin at high resolution.

    Science.gov (United States)

    Bianchin, Alessandra; Allemand, Frederic; Bell, Angus; Chubb, Anthony J; Guichou, Jean François

    2015-06-01

    Antimalarial chemotherapy continues to be challenging in view of the emergence of drug resistance, especially artemisinin resistance in Southeast Asia. It is critical that novel antimalarial drugs are identified that inhibit new targets with unexplored mechanisms of action. It has been demonstrated that the immunosuppressive drug rapamycin, which is currently in clinical use to prevent organ-transplant rejection, has antimalarial effects. The Plasmodium falciparum target protein is PfFKBP35, a unique immunophilin FK506-binding protein (FKBP). This protein family binds rapamycin, FK506 and other immunosuppressive and non-immunosuppressive macrolactones. Here, two crystallographic structures of rapamycin in complex with the FK506-binding domain of PfFKBP35 at high resolution, in both its oxidized and reduced forms, are reported. In comparison with the human FKBP12-rapamycin complex reported previously, the structures reveal differences in the β4-β6 segment that lines the rapamycin binding site. Structural differences between the Plasmodium protein and human hFKBP12 include the replacement of Cys106 and Ser109 by His87 and Ile90, respectively. The proximity of Cys106 to the bound rapamycin molecule (4-5 Å) suggests possible routes for the rational design of analogues of rapamycin with specific antiparasitic activity. Comparison of the structures with the PfFKBD-FK506 complex shows that both drugs interact with the same binding-site residues. These two new structures highlight the structural differences and the specific interactions that must be kept in consideration for the rational design of rapamycin analogues with antimalarial activity that specifically bind to PfFKBP35 without immunosuppressive effects.

  7. High-cadence observations of CME initiation and plasma dynamics in the corona with TESIS on board CORONAS-Photon

    Science.gov (United States)

    Bogachev, Sergey; Kuzin, Sergey; Zhitnik, I. A.; Bugaenko, O. I.; Goncharov, A. L.; Ignatyev, A. P.; Krutov, V. V.; Lomkova, V. M.; Mitrofanov, A. V.; Nasonkina, T. P.; Oparin, S. N.; Petzov, A. A.; Shestov, S. V.; Slemzin, V. A.; Soloviev, V. A.; Suhodrev, N. K.; Shergina, T. A.

    The TESIS is an ensemble of space instruments designed in Lebedev Institute of Russian Academy of Sciences for spectroscopic and imaging investigation of the Sun in EUV and soft X-ray spectral range with high spatial, temporal and spectral resolution. From 2009 January, when TESIS was launched onboard the Coronas-Photon satellite, it provided about 200 000 new images and spectra of the Sun, obtained during one of the deepest solar minimum in last century. Because of the wide field of view (4 solar radii) and high sensitivity, TESIS provided high-quality data on the origin and dynamics of eruptive prominences and CMEs in the low and intermediate solar corona. TESIS is also the first EUV instrument which provided high-cadence observations of coronal bright points and solar spicules with temporal resolution of a few seconds. We present first results of TESIS observations and discuss them from a scientific point of view.

  8. Degradation of 2,4-dinitroanisole (DNAN) by metabolic cooperative activity of Pseudomonas sp. strain FK357and Rhodococcus imtechensis strain RKJ300.

    Science.gov (United States)

    Khan, Fazlurrahman; Pal, Deepika; Ghosh, Anuradha; Cameotra, Swaranjit Singh

    2013-11-01

    2,4-Dinitroanisole (DNAN) is an insensitive explosive ingredient used by many defense agencies as a replacement for 2,4,6-trinitrotoluene. Although the biotransformation of DNAN under anaerobic condition has been reported, aerobic microbial degradation pathway has not been elucidated. An n-methyl-4-nitroaniline degrading bacterium Pseudomonas sp. strain FK357 transformed DNAN into 2,4-dinitrophenol (2,4-DNP) as an end product. Interestingly, when strain FK357 was co-cultured with a 2,4-DNP degrading Rhodococcus imtechensis strain RKJ300, complete and high rate of DNAN degradation was observed with no accumulation of intermediates. Enzyme assay using cell extracts of strain FK357 demonstrated that O-demethylation reaction is the first step of DNAN degradation with formation of 2,4-DNP and formaldehyde as intermediates. Subsequently, 2,4-DNP was degraded by strain RKJ300 via the formation of hydride-Meisenheimer complex. The present study clearly demonstrates that complete degradation of DNAN occurs as a result of the metabolic cooperative activity of two members within a bacterial consortium.

  9. Feynman-Kleinert Linearized Path Integral (FK-LPI) Algorithms for Quantum Molecular Dynamics, with Application to Water and He(4).

    Science.gov (United States)

    Poulsen, Jens Aage; Nyman, Gunnar; Rossky, Peter J

    2006-11-01

    The Feynman-Kleinert Linearized Path Integral (FK-LPI) representation of quantum correlation functions is extended in applications and algorithms. Diffusion including quantum effects for a flexible simple point charge model of liquid water is explored, including new tests of internal consistency. An ab initio quantum correction factor (QCF) is also obtained to correct the far-infrared spectrum of water. After correction, a spectrum based on a classical simulation is in good agreement with the experiment. The FK-LPI QCF is shown to be superior to the so-called harmonic QCF. New computational algorithms are introduced so that the quantum Boltzmann Wigner phase-space density, the central object in the implementation, can be obtained for arbitrary potentials. One scheme requires only that the standard classical force routine be replaced when turning from one molecular problem to another. The new algorithms are applied to the calculation of the Van Hove spectrum of liquid He(4) at 27 K. The spectrum moments are in very good agreement with the experiment. These observations indicate that the FK-LPI approach can be broadly effective for molecular problems involving the dynamics of light nuclei.

  10. Effect of FK506 and cyclosporine A on the expression of BDNF, tyrosine kinase B and p75 neurotrophin receptors in astrocytes exposed to simulated ischemia in vitro.

    Science.gov (United States)

    Gabryel, Bozena; Bernacki, Jacek

    2009-07-01

    We investigated whether the immunosuppressive drugs, FK506 and cyclosporine A, increase BDNF protein and/or mRNA expression in ischemic astrocytes and if an increase could be related to changes in the nuclear expression of p-CREB, p-Erk1/2 and p-Akt. The influence of these immunosuppressants on protein and mRNA levels of TrkB and p75(NTR) receptors was also examined. On day 21, cultures of rat astrocytes were subjected to ischemic conditions simulated in vitro (combined oxygen glucose deprivation, OGD) for 8h and exposed to FK506 (10-1000nM) and cyclosporine A (0.25-10microM). FK506 and cyclosporine A (at 1000nM and 0.25microM, respectively) stimulated the expression and release of BDNF in cultured rat cerebral cortical astrocytes exposed to OGD. The immunosuppressants at these doses simultaneously increased p-CREB and p-Erk1/2 expression in the nuclear fraction of astrocytes. The results RT-PCR and Western blot analysis provided further evidence of a modulating influence of the drugs on the expression of trkB and p75(NTR) genes and their protein products in ischemic astrocytes.

  11. Ginkgo biloba extract (EGb761) and FK506 preserve energy metabolites in the striatum during focal cerebral ischemia and reperfusion in gerbils monitored by microdialysis.

    Science.gov (United States)

    Lin, Jing-Ying; Cheng, Fu-Chou; Chung, Shu-Ying; Lin, Ming-Cheng

    2004-01-01

    Cell death after cerebral ischemia is mediated by the accumulation of excitatory amino acids, calcium influx into cells and the generation of free radicals. The aim of this study was to evaluate changes in energy-related metabolites in the striatum of gerbils subjected to focal cerebral ischemia after pretreatment with Ginkgo biloba extract (EGb761), a well-known antioxidant, and FK506, a calcium-dependent phosphatase calcineurin inhibitor. Ischemia was induced by occlusion of the right common carotid artery and the right middle cerebral artery for 60 min. A microdialysis probe was inserted into the right striatum to monitor extracellular glucose, lactate and pyruvate levels. This study showed decreases in glucose (10% of the baseline), pyruvate (20% of the baseline) and lactate (60% of the baseline), and a 5-fold increase in the lactate to pyruvate ratio during ischemia in the control group. Both EGb761 treatment and the combination (EGb761 and FK506) therapy significantly preserved glucose (50% of the baseline) and pyruvate (60% of the baseline) levels during ischemia. The marked increase in the lactate to pyruvate ratio was not observed in the combination group. These results suggest that preservation of cellular energy metabolism during cerebral ischemia and after restoration with reperfusion may contribute to the neuroprotective effects of EGb761 and FK506.

  12. The role of photoionization in negative corona discharge: The influences of temperature, humidity, and air pressure on a corona

    Science.gov (United States)

    Sun, H. Y.; Lu, B. X.; Wang, M.; Guo, Q. F.; Feng, Q. K.

    2017-10-01

    The swarm parameters of the negative corona discharge are improved to calculate the discharge model under different environmental conditions. The effects of temperature, humidity, and air pressure are studied using a conventional needle-to-plane configuration in air. The electron density, electric field, electron generation rate, and photoelectron generation rate are discussed in this paper. The role of photoionization under these conditions is also studied by numerical simulation. The photoelectrons generated in weak ionization region are proved to be dominant.

  13. DC negative corona discharge in atmospheric pressure helium: transition from the corona to the ‘normal’ glow regime

    Science.gov (United States)

    Hasan, Nusair; Antao, Dion S.; Farouk, Bakhtier

    2014-06-01

    Direct current (dc) negative corona discharges in atmospheric pressure helium are simulated via detailed numerical modeling. Simulations are conducted to characterize the discharges in atmospheric helium for a pin plate electrode configuration. A self-consistent two-dimensional hybrid model is developed to simulate the discharges and the model predictions are validated with experimental measurements. The discharge model considered consists of momentum and energy conservation equations for a multi-component (electrons, ions, excited species and neutrals) gas mixture, conservation equations for each component of the mixture and state relations. A drift-diffusion approximation for the electron and the ion fluxes is used. A model for the external circuit driving the discharge is also considered and solved along with the discharge model. Many of the key features of a negative corona discharge, namely non-linear current-voltage characteristics, spatially flat cathode current density and glow-like discharge in the high current regime are displayed in the predictions. A transition to the ‘normal’ glow discharge from the corona discharge regime is also observed. The transition is identified from the calculated current-voltage characteristic curve and is characterized by the radial growth of the negative glow and the engulfment of the cathode wire.

  14. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts

    OpenAIRE

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-01-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging perform...

  15. Potentiation by nitric oxide of cyclosporin A and FK506-induced apoptosis in renal proximal tubule cells.

    Science.gov (United States)

    Hortelano, S; Castilla, M; Torres, A M; Tejedor, A; Boscá, L

    2000-12-01

    Proximal tubular epithelial cells (PTEC) exhibit a high sensitivity to undergo apoptosis in response to proinflammatory stimuli and immunosuppressors and participate in the onset of several renal diseases. This study examined the expression of inducible nitric oxide (NO) synthase after challenge of PTEC with bacterial cell wall molecules and inflammatory cytokines and analyzed the pathways that lead to apoptosis in these cells by measuring changes in the mitochondrial transmembrane potential and caspase activation. The data show that the apoptotic effects of proinflammatory stimuli mainly were due to the expression of inducible NO synthase. Cyclosporin A and FK506 inhibited partially NO synthesis. However, both NO and immunosuppressors induced apoptosis, probably through a common mechanism that involved the irreversible opening of the mitochondrial permeability transition pore. Activation of caspases 3 and 7 was observed in cells treated with high doses of NO and with moderate concentrations of immunosuppressors. The conclusion is that the cooperation between NO and immunosuppressors that induce apoptosis in PTEC might contribute to the renal toxicity observed in the course of immunosuppressive therapy.

  16. Structural basis of nucleic acid recognition by FK506-binding protein 25 (FKBP25), a nuclear immunophilin.

    Science.gov (United States)

    Prakash, Ajit; Shin, Joon; Rajan, Sreekanth; Yoon, Ho Sup

    2016-04-07

    The nuclear immunophilin FKBP25 interacts with chromatin-related proteins and transcription factors and is suggested to interact with nucleic acids. Currently the structural basis of nucleic acid binding by FKBP25 is unknown. Here we determined the nuclear magnetic resonance (NMR) solution structure of full-length human FKBP25 and studied its interaction with DNA. The FKBP25 structure revealed that the N-terminal helix-loop-helix (HLH) domain and C-terminal FK506-binding domain (FKBD) interact with each other and that both of the domains are involved in DNA binding. The HLH domain forms major-groove interactions and the basic FKBD loop cooperates to form interactions with an adjacent minor-groove of DNA. The FKBP25-DNA complex model, supported by NMR and mutational studies, provides structural and mechanistic insights into the nuclear immunophilin-mediated nucleic acid recognition. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  17. Genome-wide identification and analysis of FK506-binding protein family gene family in strawberry (Fragaria × ananassa).

    Science.gov (United States)

    Leng, Xiangpeng; Liu, Dan; Zhao, Mizhen; Sun, Xin; Li, Yu; Mu, Qian; Zhu, Xudong; Li, Pengyu; Fang, Jinggui

    2014-01-25

    The FK506 binding proteins (FKBPs) are abundant and ubiquitous proteins belonging to the large peptidyl-prolylcis-trans isomerase superfamily. FKBPs are known to be involved in many biological processes including hormone signaling, plant growth, and stress responses through a chaperone or an isomerization of proline residues during protein folding. The availability of complete strawberry genome sequences allowed the identification of 23 FKBP genes by HMMER and blast analysis. Chromosome scaffold locations of these FKBP genes in the strawberry genome were determined and the protein domain and motif organization of FaFKBPs analyzed. The phylogenetic relationships between strawberry FKBPs were also assessed. The expression profiles of FaFKBPs genes results revealed that most FaFKBPs were expressed in all tissues, while a few FaFKBPs were specifically expressed in some of the tissues. These data not only contribute to some better understanding of the complex regulation of the strawberry FKBP gene family, but also provide valuable information for further research in strawberry functional genomics.

  18. Mg II h + k emission lines as stellar activity indicators of main sequence F-K stars

    CERN Document Server

    Buccino, Andrea P

    2008-01-01

    The main purpose of this study is to use the IUE spectra in the analysis of magnetic activity of main sequence F-K stars. Combining IUE observations of MgII and optical spectroscopy of Ca II, the registry of ctivity of stars can be extended in time. We retrieved all the high-resolution spectra of F, G, and K main sequence stars observed by IUE (i.e. 1623 spectra of 259 F to K dwarf stars). We obtained the continuum surface flux near the Mg II h+k lines near 2800 \\AA and the MgII line-core surface flux from the IUE spectra. We obtained a relation between the mean continuum flux near the MgII lines with the colour $B-V$ of the star. For a set of 117 nearly simultaneous observations of Mg II and Ca II fluxes of 21 F5 to K3 main sequence stars, we obtained a colour dependent relation between the Mount Wilson CaII S-index and the MgII emission line-core flux. As an application of this calibration, we computed the Mount Wilson index for all the dF to dK stars which have high resolution IUE spectra. For some of the ...

  19. Block copolymer micelle coronas as quasi-two-dimensional dilute or semidilute polymer solutions

    DEFF Research Database (Denmark)

    Svaneborg, C.; Pedersen, J.S.

    2001-01-01

    Chain-chain interactions in a corona of polymers tethered to a spherical core under good solvent conditions are studied using Monte Carlo simulations. The total scattering function of the corona as well as different partial contributions are sampled. By combining the different contributions...... in a self-consistent approach, it is demonstrated that the corona can be regarded as a quasi-two-dimensional polymer solution, with a concentration dependence analogous to that of an ordinary polymer solution. Scattering due to the corona profile and density fluctuation correlations are separated...

  20. Research on Nanosecond Pulse Corona Discharge with Cross Magnetic Field Applied

    Institute of Scientific and Technical Information of China (English)

    HE Zheng-hao; YU Fu-sheng; HU Feng; YUAN Yun; GUO Li-na; LI Jin

    2007-01-01

    An application of magnetic field to the nanosecond pulse corona discharge is investigated.A cylinder reactor with different corona electodes is set up for experimental study.A manetic field with its direction perpendicular to the corona discharge is applied.Different discharge images are taken under single nanosecond pulse with a high sensitive UV-visible light imagine recorder.Experimental results show that with a cross magnetic field the nanosecond out the magnetic field. The results may lead to a possibility to apply a cross magnetic field on nanosecond pulse corona discharge for getting higher desulfurization effciency.

  1. Impact of protein pre-coating on the protein corona composition and nanoparticle cellular uptake.

    Science.gov (United States)

    Mirshafiee, Vahid; Kim, Raehyun; Park, Soyun; Mahmoudi, Morteza; Kraft, Mary L

    2016-01-01

    Nanoparticles (NPs) are functionalized with targeting ligands to enable selectively delivering drugs to desired locations in the body. When these functionalized NPs enter the blood stream, plasma proteins bind to their surfaces, forming a protein corona that affects NP uptake and targeting efficiency. To address this problem, new strategies for directing the formation of a protein corona that has targeting capabilities are emerging. Here, we have investigated the feasibility of directing corona composition to promote targeted NP uptake by specific types of cells. We used the well-characterized process of opsonin-induced phagocytosis by macrophages as a simplified model of corona-mediated NP uptake by a desired cell type. We demonstrate that pre-coating silica NPs with gamma-globulins (γ-globulins) produced a protein corona that was enriched with opsonins, such as immunoglobulins. Although immunoglobulins are ligands that bind to receptors on macrophages and elicit phagocytois, the opsonin-rich protein corona did not increase NP uptake by macrophage RAW 264.7 cells. Immunolabeling experiments indicated that the binding of opsonins to their target cell surface receptors was impeded by other proteins in the corona. Thus, corona-mediated NP targeting strategies must optimize both the recruitment of the desired plasma proteins as well as their accessibility and orientation in the corona layer.

  2. Elastin-based protein polymer nanoparticles carrying drug at both corona and core suppress tumor growth in vivo.

    Science.gov (United States)

    Shi, Pu; Aluri, Suhaas; Lin, Yi-An; Shah, Mihir; Edman, Maria; Dhandhukia, Jugal; Cui, Honggang; MacKay, J Andrew

    2013-11-10

    Numerous nanocarriers of small molecules depend on either non-specific physical encapsulation or direct covalent linkage. In contrast, this manuscript explores an alternative encapsulation strategy based on high-specificity avidity between a small molecule drug and its cognate protein target fused to the corona of protein polymer nanoparticles. With the new strategy, the drug associates tightly to the carrier and releases slowly, which may decrease toxicity and promote tumor accumulation via the enhanced permeability and retention effect. To test this hypothesis, the drug Rapamycin (Rapa) was selected for its potent anti-proliferative properties, which give it immunosuppressant and anti-tumor activity. Despite its potency, Rapa has low solubility, low oral bioavailability, and rapid systemic clearance, which make it an excellent candidate for nanoparticulate drug delivery. To explore this approach, genetically engineered diblock copolymers were constructed from elastin-like polypeptides (ELPs) that assemble small (nanoparticles. ELPs are protein polymers of the sequence (Val-Pro-Gly-Xaa-Gly)n, where the identity of Xaa and n determine their assembly properties. Initially, a screening assay for model drug encapsulation in ELP nanoparticles was developed, which showed that Rose Bengal and Rapa have high non-specific encapsulation in the core of ELP nanoparticles with a sequence where Xaa=Ile or Phe. While excellent at entrapping these drugs, their release was relatively fast (2.2h half-life) compared to their intended mean residence time in the human body. Having determined that Rapa can be non-specifically entrapped in the core of ELP nanoparticles, FK506 binding protein 12 (FKBP), which is the cognate protein target of Rapa, was genetically fused to the surface of these nanoparticles (FSI) to enhance their avidity towards Rapa. The fusion of FKBP to these nanoparticles slowed the terminal half-life of drug release to 57.8h. To determine if this class of drug

  3. Observational capabilities of solar satellite "Coronas-Photon"

    Science.gov (United States)

    Kotov, Yu.

    Coronas-Photon mission is the third satellite of the Russian Coronas program on solar activity observation The main goal of the Coronas-Photon is the study of solar hard electromagnetic radiation in the wide energy range from UV up to high energy gamma-radiation sim 2000MeV Scientific payload for solar radiation observation consists of three type of instruments 1 monitors Natalya-2M Konus-RF RT-2 Penguin-M BRM Phoka Sphin-X Sokol for spectral and timing measurements of full solar disk radiation with timing in flare burst mode up to one msec Instruments Natalya-2M Konus-RF RT-2 will cover the wide energy range of hard X-rays and soft Gamma rays 15keV to 2000MeV and will together constitute the largest area detectors ever used for solar observations Detectors of gamma-ray monitors are based on structured inorganic scintillators with energy resolution sim 5 for nuclear gamma-line band to 35 for GeV-band PSD analysis is used for gamma neutron separation for solar neutron registration T 30MeV Penguin-M has capability to measure linear polarization of hard X-rays using azimuth are measured by Compton scattering asymmetry in case of polarization of an incident flux For X-ray and EUV monitors the scintillation phoswich detectors gas proportional counter CZT assembly and Filter-covered Si-diodes are used 2 Telescope-spectrometer TESIS for imaging solar spectroscopy in X-rays with angular resolution up to 1 in three spectral lines and RT-2 CZT assembly of CZT

  4. Pulsed corona discharge at atmospheric and supercritical conditions

    Science.gov (United States)

    Lock, Evgeniya Hristova

    Pulsed corona discharge is one of the non-equilibrium plasma techniques, by which electrical power is mainly utilized to generate high-energy electrons. These react further with the background gas to produce radicals, which can be further employed in chemically selective reactions. Study of the initiation of pulsed corona discharge in carbon dioxide and air was conducted. Furthermore due to its high removal efficiency, energy yields and good economy, the pulsed corona discharge was employed for removal of methanol and dimethyl sulfide. These compounds are part of the volatile organic compounds (VOC) air pollutants, which are subject of severe environmental regulations due to their toxicity, environmental persistence and intensity of smell. The study provides experimental data for the destruction of methanol and dimethyl sulfide from dry and humid air streams. The effects of the process parameters, including applied voltage, pulse repetition rate, initial concentration of pollutants, temperature and humidity on the destruction and removal efficiency and energy cost are analyzed. Specific consideration is given to the formation of unwanted byproducts. The study on plasma application for pollution control showed that small amounts of dispersed liquid droplets increase the efficiency of the chemical utilization of the high-energy electrons and reduce the required power. So media that could facilitate homogeneous and heterogeneous chemistry at the same time would enhance the efficiency of the removal process. Such medium that has properties intermediate between the gas and liquid phase is the supercritical fluid. Generation of plasma in supercritical fluids is an unexplored area in plasma science. The generation of plasma at elevated pressures usually requires high voltages or small interelectrode distances. The supercritical phase is characterized by extensive cluster formation in the vicinity of the critical point. Typically the clusters have lower ionization

  5. Evaluación estética de seis tipos de coronas para dientes primarios

    Directory of Open Access Journals (Sweden)

    Héctor Alejandro Ramírez Peña

    2017-03-01

    Full Text Available Objetivo: Evaluar las preferencias estéticas en relación con el color y la forma de coronas primarias utilizadas para dientes incisivos superiores primarios, mediante la realización de una encuesta a miembros de la Academia Mexicana de Odontología Pediatrica (AMOP. Material y Métodos: Se establecieron seis grupos de estudio con seis coronas diferentes: grupo 1, coronas de zirconia EZ-Pedo; grupo 2, coronas de zirconia NuSmile Zr; grupo 3, coronas estéticas hechas en el consultorio; grupo 4, coronas de fundas de celuloide; grupo 5, coronas estéticas prefabricadas NuSmile signature; y grupo 6, coronas estéticas fenestradas. Se llevaron a cabo encuestas con la finalidad de conocer las preferencias estéticas de estas diferentes coronas, con la finalidad de conocer cuál es la mejor opción para su uso en el consultorio dental. Resultados: Noventa miembros de la AMOP realizaron una encuesta válida, y se determinó que el grupo 4 fue el mejor evaluado, seguido de los grupos 2, 5, 1, 6 y 3. Se identificaron diferencias significativas entre los diferentes grupos. Conclusiones: Las coronas de fundas de celuloide fueron seleccionadas como mejor alternativa de uso en los dientes primarios anteriores, por parte de los miembros de la AMOP; asimismo, se consideró a las coronas de zirconia como una buena opción terapéutica. Es recomendable que se implemente el tratamiento estético en dientes primarios, para realizar un tratamiento integral.

  6. Modeling of Carbon Monoxide Removal by Corona Plasma

    Institute of Scientific and Technical Information of China (English)

    FENG Jingwei; SUN Yabing; ZHAO Dayong; ZHENG Zheng; XU Yuewu; YANG Haifeng; ZHU Hongbiao; ZHOU Xiaoxia

    2009-01-01

    Modeling of carbon monoxide (CO) removal by a corona plasma was conducted in this study.The purification efficiency of CO was calculated theoretically and the factors affecting the removal of CO were analyzed.The results showed that the main removal mechanisms of CO were direct dissociation by generated high-energy electrons and indirect oxidation by generated hydroxyl radicals.The purification efficiency of CO was dependent on the plasma parameters,indoor air humidity and initial concentration of CO.Good consistency between the theoretical calculation and the experimental results was observed.

  7. Fluorine in R Coronae Borealis and Extreme Helium Stars

    CERN Document Server

    Pandey, Gajendra; Rao, N Kameswara

    2007-01-01

    Neutral fluorine lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is enriched in some RCBs by factors of 800 to 8000 relative to its likely initial abundance. The overabundances of fluorine are evidence for the synthesis of fluorine. These results are discussed in the light of the scenario that RCBs are formed by accretion of an He white dwarf by a C-O white dwarf. Sakurai's object (V4334 Sgr), a final He-shell flash product, shows no detectable neutral fluorine lines.

  8. The prestellar and protostellar population of R Coronae Australis

    CERN Document Server

    Nutter, D J; André, P; Nutter, David J.

    2004-01-01

    We present 450 and 850 um maps of R Coronae Australis. We compare the maps to previous surveys of the region, and shed new light on the previously unknown nature of the protostellar sources at the centre of the cloud. We clarify the nature of two millimetre sources previously discovered in lower resolution data. We identify one new Class 0 protostar that we label SMM 1B, and we measure the envelope masses of a number of more evolved protostars. We identify two new prestellar cores that we call SMM 1A and SMM 6.

  9. Degradation Processes in Corona-Charged Electret Filter-Media

    Directory of Open Access Journals (Sweden)

    Warren J. Jasper, Ph.D

    2007-12-01

    Full Text Available The degradation of filtration performance for coronachargedelectret filter media exposed to ethyl benzenewas assessed. Nonwoven corona-charged polypropylenefiber mats were exposed to ethyl-benzene using acustom made apparatus. Evaluated scenarios includedethyl-benzene vapor and liquid exposures. The filtrationperformance was evaluated using DOP as a testaerosol to measure filtration performance. It was observedthat significant filtration degradation occurredonly when liquid ethyl benzene came into direct contactwith the filter media. No significant changes in thepressure drop or filtration efficiency was observed forany of the exposure scenarios in which the fibers wereonly exposed to ethyl benzene in the vapor phase.

  10. A History of Satellite Reconnaissance. Volume 1. CORONA (REDACTED)

    Science.gov (United States)

    1973-10-01

    recalled some 15 years later, have been summarized in CIA Intelligence Journal , July l973.. 31 Tma-sscasir-- BYE 17017-74 Handle via Byernan/ Taient...professional for an "amateur" perhaps explained much of the implied distrust. BYZ 17017- Handle yet Byeman/ Talent - Keyn• Controls OrTOP -SECRE-T 83 1...used here and not otherwise attributed have been taken from "CORONA, " by Kenneth E. Greer, an article published in the CIA Intelligence Journal of July

  11. Deficiency of FK506-binding protein (FKBP) 51 alters sleep architecture and recovery sleep responses to stress in mice.

    Science.gov (United States)

    Albu, Stefana; Romanowski, Christoph P N; Letizia Curzi, M; Jakubcakova, Vladimira; Flachskamm, Cornelia; Gassen, Nils C; Hartmann, Jakob; Schmidt, Mathias V; Schmidt, Ulrike; Rein, Theo; Holsboer, Florian; Hausch, Felix; Paez-Pereda, Marcelo; Kimura, Mayumi

    2014-04-01

    FK506-binding protein 51 (FKBP51) is a co-chaperone of the glucocorticoid receptor, functionally linked to its activity via an ultra-short negative feedback loop. Thus, FKBP51 plays an important regulatory role in the hypothalamic-pituitary-adrenocortical (HPA) axis necessary for stress adaptation and recovery. Previous investigations illustrated that HPA functionality is influenced by polymorphisms in the gene encoding FKBP51, which are associated with both increased protein levels and depressive episodes. Because FKBP51 is a key molecule in stress responses, we hypothesized that its deletion impacts sleep. To study FKBP51-involved changes in sleep, polysomnograms of FKBP51 knockout (KO) mice and wild-type (WT) littermates were compared at baseline and in the recovery phase after 6-h sleep deprivation (SD) and 1-h restraint stress (RS). Using another set of animals, the 24-h profiles of hippocampal free corticosterone levels were also determined. The most dominant effect of FKBP51 deletion appeared as increased nocturnal wake, where the bout length was significantly extended while non-rapid eye movement sleep (NREMS) and rapid eye movement sleep were rather suppressed. After both SD and RS, FKBP51KO mice exhibited less recovery or rebound sleep than WTs, although slow-wave activity during NREMS was higher in KOs, particularly after SD. Sleep compositions of KOs were nearly opposite to sleep profiles observed in human depression. This might result from lower levels of free corticosterone in FKBP51KO mice, confirming reduced HPA reactivity. The results indicate that an FKBP51 deletion yields a pro-resilience sleep phenotype. FKBP51 could therefore be a therapeutic target for stress-induced mood and sleep disorders.

  12. Aerobic degradation of N-methyl-4-nitroaniline (MNA by Pseudomonas sp. strain FK357 isolated from soil.

    Directory of Open Access Journals (Sweden)

    Fazlurrahman Khan

    Full Text Available N-Methyl-4-nitroaniline (MNA is used as an additive to lower the melting temperature of energetic materials in the synthesis of insensitive explosives. Although the biotransformation of MNA under anaerobic condition has been reported, its aerobic microbial degradation has not been documented yet. A soil microcosms study showed the efficient aerobic degradation of MNA by the inhabitant soil microorganisms. An aerobic bacterium, Pseudomonas sp. strain FK357, able to utilize MNA as the sole carbon, nitrogen, and energy source, was isolated from soil microcosms. HPLC and GC-MS analysis of the samples obtained from growth and resting cell studies showed the formation of 4-nitroaniline (4-NA, 4-aminophenol (4-AP, and 1, 2, 4-benzenetriol (BT as major metabolic intermediates in the MNA degradation pathway. Enzymatic assay carried out on cell-free lysates of MNA grown cells confirmed N-demethylation reaction is the first step of MNA degradation with the formation of 4-NA and formaldehyde products. Flavin-dependent transformation of 4-NA to 4-AP in cell extracts demonstrated that the second step of MNA degradation is a monooxygenation. Furthermore, conversion of 4-AP to BT by MNA grown cells indicates the involvement of oxidative deamination (release of NH2 substituent reaction in third step of MNA degradation. Subsequent degradation of BT occurs by the action of benzenetriol 1, 2-dioxygenase as reported for the degradation of 4-nitrophenol. This is the first report on aerobic degradation of MNA by a single bacterium along with elucidation of metabolic pathway.

  13. N-terminal and Central Segments of the Type 1 Ryanodine Receptor Mediate Its Interaction with FK506-binding Proteins*

    Science.gov (United States)

    Girgenrath, Tanya; Mahalingam, Mohana; Svensson, Bengt; Nitu, Florentin R.; Cornea, Razvan L.; Fessenden, James D.

    2013-01-01

    We used site-directed labeling of the type 1 ryanodine receptor (RyR1) and fluorescence resonance energy transfer (FRET) measurements to map RyR1 sequence elements forming the binding site of the 12-kDa binding protein for the immunosuppressant drug, FK506. This protein, FKBP12, promotes the RyR1 closed state, thereby inhibiting Ca2+ leakage in resting muscle. Although FKBP12 function is well established, its binding determinants within the RyR1 protein sequence remain unresolved. To identify these sequence determinants using FRET, we created five single-Cys FKBP variants labeled with Alexa Fluor 488 (denoted D-FKBP) and then targeted these D-FKBPs to full-length RyR1 constructs containing decahistidine (His10) “tags” placed within N-terminal (amino acid residues 76–619) or central (residues 2157–2777) regions of RyR1. The FRET acceptor Cy3NTA bound specifically and saturably to these His tags, allowing distance analysis of FRET measured from each D-FKBP variant to Cy3NTA bound to each His tag. Results indicate that D-FKBP binds proximal to both N-terminal and central domains of RyR1, thus suggesting that the FKBP binding site is composed of determinants from both regions. These findings further imply that the RyR1 N-terminal and central domains are proximal to one another, a core premise of the domain-switch hypothesis of RyR function. We observed FRET from GFP fused at position 620 within the N-terminal domain to central domain His-tagged sites, thus further supporting this hypothesis. Taken together, these results support the conclusion that N-terminal and central domain elements are closely apposed near the FKBP binding site within the RyR1 three-dimensional structure. PMID:23585572

  14. N-terminal and central segments of the type 1 ryanodine receptor mediate its interaction with FK506-binding proteins.

    Science.gov (United States)

    Girgenrath, Tanya; Mahalingam, Mohana; Svensson, Bengt; Nitu, Florentin R; Cornea, Razvan L; Fessenden, James D

    2013-05-31

    We used site-directed labeling of the type 1 ryanodine receptor (RyR1) and fluorescence resonance energy transfer (FRET) measurements to map RyR1 sequence elements forming the binding site of the 12-kDa binding protein for the immunosuppressant drug, FK506. This protein, FKBP12, promotes the RyR1 closed state, thereby inhibiting Ca(2+) leakage in resting muscle. Although FKBP12 function is well established, its binding determinants within the RyR1 protein sequence remain unresolved. To identify these sequence determinants using FRET, we created five single-Cys FKBP variants labeled with Alexa Fluor 488 (denoted D-FKBP) and then targeted these D-FKBPs to full-length RyR1 constructs containing decahistidine (His10) "tags" placed within N-terminal (amino acid residues 76-619) or central (residues 2157-2777) regions of RyR1. The FRET acceptor Cy3NTA bound specifically and saturably to these His tags, allowing distance analysis of FRET measured from each D-FKBP variant to Cy3NTA bound to each His tag. Results indicate that D-FKBP binds proximal to both N-terminal and central domains of RyR1, thus suggesting that the FKBP binding site is composed of determinants from both regions. These findings further imply that the RyR1 N-terminal and central domains are proximal to one another, a core premise of the domain-switch hypothesis of RyR function. We observed FRET from GFP fused at position 620 within the N-terminal domain to central domain His-tagged sites, thus further supporting this hypothesis. Taken together, these results support the conclusion that N-terminal and central domain elements are closely apposed near the FKBP binding site within the RyR1 three-dimensional structure.

  15. An economic evaluation of rosuvastatin treatment in systolic heart failure : evidence from the CORONA trial

    NARCIS (Netherlands)

    Lorgelly, Paula K.; Briggs, Andrew H.; Wedel, Hans; Dunselman, Peter; Hjalmarson, Ake; Kjekshus, John; Waagstein, Finn; Wikstrand, John; Janosi, Andras; van Veldhuisen, Dirk J.; Barrios, Vivencio; Fonseca, Candida; McMurray, John J. V.

    2010-01-01

    To estimate the cost-effectiveness of 10 mg rosuvastatin daily for older patients with systolic heart failure in the Controlled Rosuvastatin Multinational Study in Heart Failure (CORONA) trial. This within trial analysis of CORONA used major cardiovascular (CV) events as the outcome measure. Resourc

  16. Electron studies of acceleration processes in the corona. [solar probe mission planning

    Science.gov (United States)

    Lin, R. P.

    1978-01-01

    The solar probe mission can obtain unique and crucially important measurements of electron acceleration, storage, and propagation processes in the corona and can probe the magnetic field structure of the corona below the spacecraft. The various energetic electron phenomena which will be sampled by the Solar Probe are described and some new techniques to probe coronal structures are suggested.

  17. Regulation of Macrophage Recognition through the Interplay of Nanoparticle Surface Functionality and Protein Corona

    NARCIS (Netherlands)

    Saha, Krishnendu; Rahimi, Mehran; Yazdani, Mandieh; Kim, Sung Tae; Moyano, Daniel F.; Hou, Singyuk; Das, Ridhha; Mout, Rubul; Rezaee, Farhad; Mahmoudi, Morteza; Rotello, Vincent M.

    Using a family of cationic gold nanoparticles (NPs) with similar size and charge, we demonstrate that proper surface engineering can control the nature and identity of protein corona in physiological serum conditions. The protein coronas were highly dependent on the hydrophobicity and arrangement of

  18. Ex situ evaluation of the composition of protein corona of intravenously injected superparamagnetic nanoparticles in rats

    NARCIS (Netherlands)

    Sakulkhu, Usawadee; Maurizi, Lionel; Mahmoudi, Morteza; Motazacker, Mahdi; de Vries, Marcel; Gramoun, Azza; Beuzelin, Marie-Gabrielle Ollivier; Vallee, Jean-Paul; Rezaee, Farhad; Hofmann, Heinrich

    2014-01-01

    It is now well recognized that the surfaces of nanoparticles (NPs) are coated with biomolecules (e. g., proteins) in a biological medium. Although extensive reports have been published on the protein corona at the surface of NPs in vitro, there are very few on the in vivo protein corona. The main re

  19. Calculation of Spark Breakdown or Corona Starting Voltages in Nonuniform Fields

    DEFF Research Database (Denmark)

    Pedersen, A.

    1967-01-01

    The processes leading to a spark breakdown or corona discharge are discussed very briefly. A quantitative breakdown criterion for use in high-voltage design is derived by which spark breakdown or corona starting voltages in nonuniform fields can be calculated. The criterion is applied to the sphere...

  20. CORONA DESTRUCTION: AN INNOVATIVE CONTROL TECHNOLOGY FOR VOCS AND AIR TOXICS

    Science.gov (United States)

    This paper discusses the work and results to date leading to the demonstration of the corona destruction process at pilot scale. The research effort in corona destruction of volatile organic compounds (VOCs) and air toxics has shown significant promise for providing a valuable co...

  1. A MHD-turbulence model for solar corona

    Science.gov (United States)

    Romeou, Z.; Velli, M.; Einaudi, G.

    2009-02-01

    The disposition of energy in the solar corona has always been a problem of great interest. It remains an open question how the low temperature photosphere supports the occurence of solar extreme phenomena. In this work, a turbulent heating mechanism for the solar corona through the framework of reduced magnetohydrodynamics (RMHD) is proposed. Two-dimensional incompressible long time simulations of the average energy disposition have been carried out with the aim to reveal the characteristics of the long time statistical behavior of a two-dimensional cross-section of a coronal loop and the importance of the photospheric time scales in the understanding of the underlying mechanisms. It was found that for a slow, shear type photospheric driving the magnetic field in the loop self-organizes at large scales via an inverse MHD cascade. The system undergoes three distinct evolutionary phases. The initial forcing conditions are quickly “forgotten” giving way to an inverse cascade accompanied with and ending up to electric current dissipation. Scaling laws are being proposed in order to quantify the nonlinearity of the system response which seems to become more impulsive for decreasing resistivity. It is also shown that few, if any, qualitative changes in the above results occur by increasing spatial resolution.

  2. Impact of Type II Spicules into the Corona

    Science.gov (United States)

    Martinez-Sykora, Juan; De Pontieu, Bart; Carlsson, Mats; Hansteen, Viggo H.; Pereira, Tiago M. D.

    2017-08-01

    In the lower solar atmosphere, the chromosphere is permeated by jets, in which plasma is propelled at speeds of 50-150 km/s into the Sun’s atmosphere or corona. Although these spicules may play a role in heating the million-degree corona and are associated with Alfvén waves that help drive the solar wind, their generation remains mysterious. We implemented in the radiative MHD Bifrost code the effects of partial ionization using the generalized Ohm’s law. This code also solves the full MHD equations with non-grey and non-LTE radiative transfer and thermal conduction along magnetic field lines. The ion-neutral collision frequency is computed using recent studies that improved the estimation of the cross sections under chromospheric conditions (Vranjes & Krstic 2013). Self-consistently driven jets (spicules type II) in magnetohydrodynamic simulations occur ubiquitously when magnetic tension is confined and transported upwards through interactions between ions and neutrals, and impulsively released to drive flows, heat plasma, generate Alfvén waves, and may play an important role in maintaining the substructure of loop fans. This mechanism explains how spicular plasma can be heated to millions of degrees and how Alfvén waves are generated in the chromosphere.

  3. Magnetic tornadoes as energy channels into the solar corona.

    Science.gov (United States)

    Wedemeyer-Böhm, Sven; Scullion, Eamon; Steiner, Oskar; van der Voort, Luc Rouppe; de la Cruz Rodriguez, Jaime; Fedun, Viktor; Erdélyi, Robert

    2012-06-27

    Heating the outer layers of the magnetically quiet solar atmosphere to more than one million kelvin and accelerating the solar wind requires an energy flux of approximately 100 to 300 watts per square metre, but how this energy is transferred and dissipated there is a puzzle and several alternative solutions have been proposed. Braiding and twisting of magnetic field structures, which is caused by the convective flows at the solar surface, was suggested as an efficient mechanism for atmospheric heating. Convectively driven vortex flows that harbour magnetic fields are observed to be abundant in the photosphere (the visible surface of the Sun). Recently, corresponding swirling motions have been discovered in the chromosphere, the atmospheric layer sandwiched between the photosphere and the corona. Here we report the imprints of these chromospheric swirls in the transition region and low corona, and identify them as observational signatures of rapidly rotating magnetic structures. These ubiquitous structures, which resemble super-tornadoes under solar conditions, reach from the convection zone into the upper solar atmosphere and provide an alternative mechanism for channelling energy from the lower into the upper solar atmosphere.

  4. An anatomical study of corona mortis and its clinical significance

    Institute of Scientific and Technical Information of China (English)

    洪华兴; 潘志军; 陈欣; 黄宗坚

    2004-01-01

    Objective: To provide detailed information of corona mortis for ilioinguinal approach as an anterior approach to the acetabulum and pelvis.Methods: The course, branches and distribution of the vascular connection between the obturator system and the external iliac or inferior epigastric systems located over the superior pubic ramus were observed on 50 hemipelvises with intact soft tissues.Results: During the dissections, 72% of the cadaveric sides had at least one communicating vessel between the obturator system and the external iliac or inferior epigastric systems on the superior pubic ramus. The average diameter of the connecting vessel was 2.6 mm (range, 2.0-4.2 mm). It coursed over the superior pubic ramus or iliopubic eminence vertically to enter the obturator foramen and exit the pelvis. The average distance from pubic symphysis to the vascular connections between the obturator and external iliac systems was 52 mm ( range, 38-68 mm).Conclusions: Vascular connections between the obturator system and the external iliac or inferior epigastric systems were found over the superior pubic ramus with a high incidence. They are prone to damage during the ilioinguinal approach as an anterior approach to the acetabulum and pelvis. Thus, corona mortis located over the superior pubic ramus deserves great attention during the ilioinguinal approach.

  5. The global distribution of magnetic helicity in the solar corona

    Science.gov (United States)

    Yeates, A. R.; Hornig, G.

    2016-10-01

    By defining an appropriate field line helicity, we apply the powerful concept of magnetic helicity to the problem of global magnetic field evolution in the Sun's corona. As an ideal-magnetohydrodynamic invariant, the field line helicity is a meaningful measure of how magnetic helicity is distributed within the coronal volume. It may be interpreted, for each magnetic field line, as a magnetic flux linking with that field line. Using magneto-frictional simulations, we investigate how field line helicity evolves in the non-potential corona as a result of shearing by large-scale motions on the solar surface. On open magnetic field lines, the helicity injected by the Sun is largely output to the solar wind, provided that the coronal relaxation is sufficiently fast. But on closed magnetic field lines, helicity is able to build up. We find that the field line helicity is non-uniformly distributed, and is highly concentrated in twisted magnetic flux ropes. Eruption of these flux ropes is shown to lead to sudden bursts of helicity output, in contrast to the steady flux along the open magnetic field lines. Movies are available at http://www.aanda.org

  6. The Role of Magnetic Helicity in Structuring the Solar Corona

    CERN Document Server

    Knizhnik, Kalman J; DeVore, C Richard

    2016-01-01

    Two of the most widely observed and yet most puzzling features of the Sun's magnetic field are coronal loops that are smooth and laminar and prominences/filaments that are strongly sheared. These two features would seem to be quite unrelated in that the loops are near their minimum-energy current-free state, whereas filaments are regions of high magnetic stress and intense electric currents. We argue that, in fact, these two features are inextricably linked in that both are due to a single process: the injection of magnetic helicity into the corona by photospheric motions and the subsequent evolution of this helicity by coronal reconnection. In this paper, we present numerical simulations of the response of a \\citet{Parker72} corona to photospheric driving motions that have varying degrees of helicity preference. We obtain four main conclusions: 1) in agreement with the helicity condensation model of \\citet{Antiochos13}, the inverse cascade of helicity by magnetic reconnection results in the formation of prom...

  7. The EUV Emission in Comet-Solar Corona Interactions

    Science.gov (United States)

    Bryans, Paul; Pesnell, William Dean; Schrijver, Carolus J.; Brown, John C.; Battams, Karl; Saint-Hilaire, Pasal; Liu, Wei; Hudson, Hugh S.

    2011-01-01

    The Atmospheric Imaging Assembly (AlA) on the Solar Dynamics Observatory (SDO) viewed a comet as it passed through the solar corona on 2011 July 5. This was the first sighting of a comet by a EUV telescope. For 20 minutes, enhanced emission in several of the AlA wavelength bands marked the path of the comet. We explain this EUV emission by considering the evolution of the cometary atmosphere as it interacts with the ambient solar atmosphere. Water ice in the comet rapidly sublimates as it approaches the Sun. This water vapor is then photodissociated, primarily by Ly-alpha, by the solar radiation field to create atomic Hand O. Other molecules present in the comet also evaporate and dissociate to give atomic Fe and other metals. Subsequent ionization of these atoms can be achieved by a number of means, including photoionization, electron impact, and charge exchange with coronal protons and other highly-charged species. Finally, particles from the cometary atmosphere are thermalized to the background temperature of the corona. Each step could cause emission in the AlA bandpasses. We will report here on their relative contribution to the emission seen in the AlA telescopes.

  8. Oscillations above sunspots from the temperature minimum to the corona

    CERN Document Server

    Kobanov, N I; Kolobov, D Y

    2013-01-01

    Context. An analysis of the oscillations above sunspots was carried out using simultaneous ground-based and Solar Dynamics Observatory (SDO) observations (SiI 10827A, HeI 10830A, FeI 6173A, 1700A, HeII 304A, FeIX 171A). Aims. Investigation of the spatial distribution of oscillation power in the frequency range 1-8 mHz for the different height levels of the solar atmosphere. Measuring the time lags between the oscillations at the different layers. Methods. We used frequency filtration of the intensity and Doppler velocity variations with Morlet wavelet to trace the wave propagation from the photosphere to the chromosphere and the corona. Results. The 15 min oscillations are concentrated near the outer penumbra in the upper photosphere (1700 A), forming a ring, that expands in the transition zone. These oscillations propagate upward and reach the corona level, where their spatial distribution resembles a fan structure. The spatial distribution of the 5 min oscillation power looks like a circle-shape structure m...

  9. Neutral Hydrogen and Its Emission Lines in the Solar Corona

    Science.gov (United States)

    Vial, Jean-Claude; Chane-Yook, Martine

    2016-12-01

    Since the Lyman-α rocket observations of Gabriel ( Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and that they offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic-equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisional and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun center) in the corona, and the integrated intensities are computed at heights up to five solar radii. We compare our results with previous computations and observations ( e.g. Lα from Ultraviolet Coronal Spectrometer) and find a rough (model-dependent) agreement. Since the Hα line is a possible candidate for ground-based polarimetry, we show that in order to detect its emission in various coronal structures, it is necessary to use a very narrow (less than 2 Å wide) bandpass filter.

  10. The global distribution of magnetic helicity in the solar corona

    CERN Document Server

    Yeates, A R

    2016-01-01

    By defining an appropriate field line helicity, we apply the powerful concept of magnetic helicity to the problem of global magnetic field evolution in the Sun's corona. As an ideal-magnetohydrodynamic invariant, the field line helicity is a meaningful measure of how magnetic helicity is distributed within the coronal volume. It may be interpreted, for each magnetic field line, as a magnetic flux linking with that field line. Using magneto-frictional simulations, we investigate how field line helicity evolves in the non-potential corona as a result of shearing by large-scale motions on the solar surface. On open magnetic field lines, the helicity injected by the Sun is largely output to the solar wind, provided that the coronal relaxation is sufficiently fast. But on closed magnetic field lines, helicity is able to build up. We find that the field line helicity is non-uniformly distributed, and is highly concentrated in twisted magnetic flux ropes. Eruption of these flux ropes is shown to lead to sudden burst...

  11. Differential rotation, flares and coronae in A to M stars

    Science.gov (United States)

    Balona, L. A.; Švanda, M.; Karlický, M.

    2016-08-01

    Kepler data are used to investigate flares in stars of all spectral types. There is a strong tendency across all spectral types for the most energetic flares to occur among the most rapidly rotating stars. Differential rotation could conceivably play an important role in enhancing flare energies. This idea was investigated, but no correlation could be found between rotational shear and the incidence of flares. Inspection of Kepler light curves shows that rotational modulation is very common over the whole spectral type range. Using the rotational light amplitude, the size distribution of starspots was investigated. Our analysis suggests that stars with detectable flares have spots significantly larger than non-flare stars, indicating that flare energies are correlated with the size of the active region. Further evidence of the existence of spots on A stars is shown by the correlation between the photometric period and the projected rotational velocity. The existence of spots indicates the presence of magnetic fields, but the fact that A stars lack coronae implies that surface convection is a necessary condition for the formation of the corona.

  12. Corongraphic Observations and Analyses of The Ultraviolet Solar Corona

    Science.gov (United States)

    Kohl, John L.

    2000-10-01

    The activities supported under NASA Grant NAG5-613 included the following: 1) reduction and scientific analysis of data from three sounding rocket flights of the Rocket Ultraviolet Coronagraph Spectrometer, 2) development of ultraviolet spectroscopic diagnostic techniques to provide a detailed empirical description of the extended solar corona, 3) extensive upgrade of the rocket instrument to become the Ultraviolet Coronal Spectrometer (UVCS) for Spartan 201,4) instrument scientific calibration and characterization, 5) observation planning and mission support for a series of five Spartan 201 missions (fully successful except for STS 87 where the Spartan spacecraft was not successfully deployed and the instruments were not activated), and 6) reduction and scientific analysis of the UVCS/Spartan 201 observational data. The Ultraviolet Coronal Spectrometer for Spartan 201 was one unit of a joint payload and the other unit was a White Light Coronagraph (WLC) provided by the High Altitude Observatory and the Goddard Space Flight Center. The two instruments were used in concert to determine plasma parameters describing structures in the extended solar corona. They provided data that could be used individually or jointly in scientific analyses. The WLC provided electron column densities in high spatial resolution and high time resolution. UVCS/Spartan provided hydrogen velocity distributions, and line of sight hydrogen velocities. The hydrogen intensities from UVCS together with the electron densities from WLC were used to determine hydrogen outflow velocities. The UVCS also provided O VI intensities which were used to develop diagnostics for velocity distributions and outflow velocities of minor ions.

  13. On the low-mass diskless population of Corona Australis

    CERN Document Server

    Martí, Belén López; Merín, Bruno; Morales-Calderón, María; Bouy, Hervé; Barrado, David; Eislöffel, Jochen

    2010-01-01

    We combine published optical and near-infrared photometry to identify new low-mass candidate members in an area of about 0.64 deg^2 in Corona Australis, using the S-parameter method developed by Comer\\'on et al. (2009). Five new candidate members of the region are selected, with estimated ages between 3 and 15 Myr, and masses between 0.05 and 0.15 M_Sun. Using Spitzer photometry, we confirm that these objects are not surrounded by optically thick disks. However, one of them is found to display excess at 24 micron, thus suggesting it harbours a disk with an inner hole. With an estimated mass of 0.07 M_Sun according to the SED fitting, this is one of the lowest-mass objects reported to possess a transitional disk. Including these new members, the fraction of disks is about 50% among the total Corona Australis population selected by the same criteria, lower than the 70% fraction reported by Sicilia-Aguilar et al. (2008) for this region. Even so, we find a ratio of transitional to primordial disks (45%) very simi...

  14. Structure of the Solar Dust Corona and its Interaction with the other Coronal Components

    CERN Document Server

    Shopov, Y Y; Stoitchkova, K; Tsankov, L T; Tanev, A; Burin, Kl; Belchev, St; Rusanov, V; Ivanov, D; Stoev, A; Muglova, P; Iliev, I

    2009-01-01

    We developed a new technique for registration of the far solar corona from ground-based observations at distances comparable to those obtained from space coronagraphs. It makes possible visualization of fine details of studied objects invisible by naked eye. Here we demonstrate that streamers of the electron corona sometimes punch the dust corona and that the shape of the dust corona may vary with time. We obtained several experimental evidences that the far coronal streamers (observed directly only from the space or stratosphere) emit only in discrete regions of the visible spectrum like resonance fluorescence of molecules and ions in comets. We found that interaction of the coronal streamers with the dust corona can produce molecules and radicals, which are known to cause the resonance fluorescence in comets.

  15. The coronas-F space mission key results for solar terrestrial physics

    CERN Document Server

    2014-01-01

    This volume is the updated and extended translation of the Russian original. It presents the results of observations of solar activity and its effects in the Earth space environment carried out from July 2001 to December 2005 on board the CORONAS-F space mission. The general characteristics of the CORONAS-F scientific payload are provided with a description of the principal experiments. The main results focus on the global oscillations of the Sun (p-modes), solar corona, solar flares, solar cosmic rays, Earth’s radiation belts, and upper atmosphere. The book will be welcomed by students, post-graduates, and scientists working in the field of solar and solar-terrestrial physics. This English edition is supplemented by sections presenting new results of the SPIRIT and TESIS experiments under the CORONAS solar program, as well as from the SONG experiment onboard the CORONAS-F satellite.

  16. Positive direct current corona discharges in single wire-duct electrostatic precipitators

    Science.gov (United States)

    Yehia, Ashraf; Abdel-Fattah, E.; Mizuno, Akira

    2016-05-01

    This paper is aimed to study the characteristics of the positive dc corona discharges in single wire-duct electrostatic precipitators. Therefore, the corona discharges were formed inside dry air fed single wire-duct reactor under positive dc voltage at the normal atmospheric conditions. The corona current-voltage characteristics curves have been measured in parallel with the ozone concentration generated inside the reactor under different discharge conditions. The corona current-voltage characteristics curves have agreed with a semi empirical equation derived from the previous studies. The experimental results of the ozone concentration generated inside the reactor were formulated in the form of an empirical equation included the different parameters that were studied experimentally. The obtained equations are valid to expect both the current-voltage characteristics curves and the corresponding ozone concentration that generates with the positive dc corona discharges inside single wire-duct electrostatic precipitators under any operating conditions in the same range of the present study.

  17. Jet magnetically accelerated from disk-corona around a rotating black hole

    CERN Document Server

    Gong, Xiaolong

    2012-01-01

    A jet acceleration model for extracting energy from disk-corona surrounding a rotating black hole is proposed. In the disk-corona scenario, we obtain the ratio of the power dissipated in the corona to the total for such disk-corona system by solving the disk dynamics equations. The analytical expression of the jet power is derived based on the electronic circuit theory of the magnetosphere. It is shown that jet power increases with the increasing black hole (BH) spin, and concentrates in the inner region of the disk-corona. In addition, we use a sample consisting of 37 radio loud quasars to explore their jet production mechanism, and show that our jet formation mechanism can simulate almost all sources with high power jet, that fail to be explained by the Blandford-Znajek (BZ) process.

  18. Intermittent heating in the solar corona employing a 3D MHD model

    CERN Document Server

    Bingert, Sven

    2011-01-01

    We investigate the spatial and temporal evolution of the heating of the corona of a cool star such as our Sun in a three-dimensional magneto-hydrodynamic (3D MHD) model. We solve the 3D MHD problem numerically in a box representing part of the (solar) corona. The energy balance includes Spitzer heat conduction along the magnetic field and optically thin radiative losses. The self-consistent heating mechanism is based on the braiding of magnetic field lines rooted in the convective photosphere. Magnetic stress induced by photospheric motions leads to currents in the atmosphere which heat the corona through Ohmic dissipation. While the horizontally averaged quantities, such as heating rate, temperature or density, are relatively constant in time, the simulated corona is highly variable and dynamic, on average reaching temperatures and densities as found in observations. The strongest heating per particle is found in the transition region from the chromosphere to the corona. The heating is concentrated in curren...

  19. Arrested development - a comparative analysis of multilayer corona textures in high-grade metamorphic rocks

    Science.gov (United States)

    Ogilvie, Paula; Gibson, Roger L.

    2017-02-01

    Coronas, including symplectites, provide vital clues to the presence of arrested reaction and preservation of partial equilibrium in metamorphic and igneous rocks. Compositional zonation across such coronas is common, indicating the persistence of chemical potential gradients and incomplete equilibration. Major controls on corona mineralogy include prevailing pressure (P), temperature (T) and water activity (aH2O) during formation, reaction duration (t) single-stage or sequential corona layer growth; reactant bulk compositions (X) and the extent of metasomatic exchange with the surrounding rock; relative diffusion rates for major components; and/or contemporaneous deformation and strain. High-variance local equilibria in a corona and disequilibrium across the corona as a whole preclude the application of conventional thermobarometry when determining P-T conditions of corona formation, and zonation in phase composition across a corona should not be interpreted as a record of discrete P-T conditions during successive layer growth along the P-T path. Rather, the local equilibria between mineral pairs in corona layers more likely reflect compositional partitioning of the corona domain during steady-state growth at constant P and T. Corona formation in pelitic and mafic rocks requires relatively dry, residual bulk rock compositions. Since most melt is lost along the high-T prograde to peak segment of the P-T path, only a small fraction of melt is generally retained in the residual post-peak assemblage. Reduced melt volumes with cooling limit length scales of diffusion to the extent that diffusion-controlled corona growth occurs. On the prograde path, the low melt (or melt-absent) volumes required for diffusion-controlled corona growth are only commonly realized in mafic igneous rocks, owing to their intrinsic anhydrous bulk composition, and in dry, residual pelitic compositions that have lost melt in an earlier metamorphic event. Experimental work characterizing rate

  20. Monte Carlo simulation of corona discharge in SF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Settaouti, A.; Settaouti, L. [Electrotechnic Department, University of Sciences and Technology, P.O. Box 1505, El-M' naouar, Oran (Algeria)

    2010-09-15

    Sulphur hexafluoride (SF{sub 6}) is one of the most widely used gaseous dielectrics for electric power systems and a number of high-voltage applications. There are many industrial applications where the electric corona discharge is used. In most cases the corona discharge is an inherently dynamic process; all parameters vary in time. Monte Carlo simulation of corona discharges in gas offers several advantages to study fundamental processes. Furthermore, it gives a fair qualitative description of the corona discharge itself as a function of space and time. This paper describes the development of negative coronas in SF{sub 6} in a point-plane gap. Detailed structure of avalanches is presented, the total field distribution, propagation of successive avalanches and ion distribution are studied. (author)

  1. Functionalized O6-Corona[6]arenes: Synthesis, Structure, and Fullerene Complexation Property.

    Science.gov (United States)

    Ren, Wen-Sheng; Zhao, Liang; Wang, Mei-Xiang

    2016-07-01

    The synthesis, structure, and fullerene complexation property of novel and functionalized On-corona[n]arenes were reported. Based on the fragment coupling strategy, ester-containing On-corona[n]arenes (n = 6, 8) were obtained readily starting from 1,4-hydroquinone and diethyl 2,5-difluoroterephthalate. Reduction of esters with LiAlH4 produced almost quantitatively hydroxymethylated On-corona[n]arenes, which underwent etherification with MeI to afford methoxymethyl-substituted On-corona[n]arenes (n = 6, 8) in good yields. The macrocycles adopt unique corona-type conformation with a large cylindroid cavity. They are strong macrocyclic host molecules to form 1:1 complexes with fullerenes C60 and C70 in toluene with an associate constant up to (1.59 ± 0.04) × 10(5) M(-1).

  2. Positive direct current corona discharges in single wire-duct electrostatic precipitators

    Energy Technology Data Exchange (ETDEWEB)

    Yehia, Ashraf, E-mail: yehia30161@yahoo.com [Department of Physics, College of Science and Humanitarian Studies at Alkharj, Prince Sattam bin Abdulaziz University, P.O. Box 83, Alkharj 11942 (Saudi Arabia); Department of Physics, Faculty of Science, Assiut University, Assiut 71516, Arab Republic of Egypt (Egypt); Abdel-Fattah, E. [Department of Physics, College of Science and Humanitarian Studies at Alkharj, Prince Sattam bin Abdulaziz University, P.O. Box 83, Alkharj 11942 (Saudi Arabia); Department of Physics, Faculty of Science, Zagazig University, Zagazig 44519, Arab Republic of Egypt (Egypt); Mizuno, Akira [Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi 441-8580 (Japan)

    2016-05-15

    This paper is aimed to study the characteristics of the positive dc corona discharges in single wire-duct electrostatic precipitators. Therefore, the corona discharges were formed inside dry air fed single wire-duct reactor under positive dc voltage at the normal atmospheric conditions. The corona current-voltage characteristics curves have been measured in parallel with the ozone concentration generated inside the reactor under different discharge conditions. The corona current-voltage characteristics curves have agreed with a semi empirical equation derived from the previous studies. The experimental results of the ozone concentration generated inside the reactor were formulated in the form of an empirical equation included the different parameters that were studied experimentally. The obtained equations are valid to expect both the current-voltage characteristics curves and the corresponding ozone concentration that generates with the positive dc corona discharges inside single wire-duct electrostatic precipitators under any operating conditions in the same range of the present study.

  3. Research Progress of Solar Corona and Interplanetary Physics in China: 2010-2012

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xinhua; XIANG Changqing

    2012-01-01

    The scientific objective of solar corona and interplanetary research is the understanding of the various phenomena related to solar activities and their effects on the space environments of the Earth. Great progress has been made in the study of solar corona and interplanetary physics by the Chinese space physics community during the past years. This paper will give a brief report about the latest progress of the corona and interplanetary research in China during the years of 2010--2012. The paper can be divided into the following parts: solar corona and solar wind, CME- ICME, magnetic reconnection, energetic particles, space plasma, space weather numerical modeling by 3D SIP-CESE MHD model, space weather prediction methods, and proposed missions. They constitute the abundant content of study for the complicated phenomena that originate from the solar corona, propagate in interplanetary space, and produce geomagnetic disturbances. All these progresses are acquired by the Chinese space physicists, either independently or through international collaborations.

  4. Understanding the nanoparticle-protein corona complexes using computational and experimental methods.

    Science.gov (United States)

    Kharazian, B; Hadipour, N L; Ejtehadi, M R

    2016-06-01

    Nanoparticles (NP) have capability to adsorb proteins from biological fluids and form protein layer, which is called protein corona. As the cell sees corona coated NPs, the protein corona can dictate biological response to NPs. The composition of protein corona is varied by physicochemical properties of NPs including size, shape, surface chemistry. Processing of protein adsorption is dynamic phenomena; to that end, a protein may desorb or leave a surface vacancy that is rapidly filled by another protein and cause changes in the corona composition mainly by the Vroman effect. In this review, we discuss the interaction between NP and proteins and the available techniques for identification of NP-bound proteins. Also we review current developed computational methods for understanding the NP-protein complex interactions.

  5. Calibration of excitation function measurement based on corona cage test results.

    Science.gov (United States)

    Lan, Lei; Chen, Xiaoyue; Wen, Xishan; Li, Wei; Xiao, Guozhou

    2016-11-01

    Corona cage approaches are crucial for research on the corona characteristics of conductors. Calibration is an indispensable task for determining excitation functions, which are used to predict corona performance of long transmission lines through extrapolation from measurements of short lines in corona cages. In this paper, the amplification factor G is calculated through a frequently adopted method, propagation analysis of high-frequency corona current along a short line. Another convenient calibration method, based on distributed parameter equivalent circuits, is established. The results for G obtained through propagation analysis and equivalent circuits are compared. To verify the rationality of calculation parameters in propagation analysis and equivalent circuits, a calibration experiment based on the excitation caused by a simulated monopulse current was performed. The results of the proposed calibration method and the calibration experiment are in good agreement.

  6. Nanoparticle corona for proteins: mechanisms of interaction between dendrimers and proteins.

    Science.gov (United States)

    Shcharbin, Dzmitry; Ionov, Maksim; Abashkin, Viktar; Loznikova, Svetlana; Dzmitruk, Volha; Shcharbina, Natallia; Matusevich, Ludmila; Milowska, Katarzyna; Gałęcki, Krystian; Wysocki, Stanisław; Bryszewska, Maria

    2015-10-01

    Protein absorption at the surface of big nanoparticles and formation of 'protein corona' can completely change their biological properties. In contrast, we have studied the binding of small nanoparticles - dendrimers - to proteins and the formation of their 'nanoparticle corona'. Three different types of interactions were observed. (1) If proteins have rigid structure and active site buried deeply inside, the 'nanoparticle corona' is unaffected. (2) If proteins have a flexible structure and their active site is also buried deeply inside, the 'nanoparticle corona' affects protein structure, but not enzymatic activity. (3) The 'nanoparticle corona' changes both the structure and enzymatic activity of flexible proteins that have surface-based active centers. These differences are important in understanding interactions taking place at a bio-nanointerface.

  7. Dimensions of Attention Associated With the Microstructure of Corona Radiata White Matter.

    Science.gov (United States)

    Stave, Elise A; De Bellis, Michael D; Hooper, Steven R; Woolley, Donald P; Chang, Suk Ki; Chen, Steven D

    2017-01-01

    Mirsky proposed a model of attention that included these dimensions: focus/execute, sustain, stabilize, encode, and shift. The neural correlates of these dimensions were investigated within corona radiata subregions in healthy youth. Diffusion tensor imaging and neuropsychological assessments were conducted in 79 healthy, right-handed youth aged 4-17 years. Diffusion tensor imaging maps were analyzed using standardized parcellation methods. Partial Pearson correlations between neuropsychological standardized scores, representing these attention dimensions, and diffusion tensor imaging measures of corona radiata subregions were calculated after adjusting for gender and IQ. Significant correlations were found between the focus/execute, sustain, stabilize, and shift dimensions and imaging metrics in hypothesized corona radiata subregions. Results suggest that greater microstructural white matter integrity of the corona radiata is partly associated with attention across 4 attention dimensions. Findings suggest that white matter microstructure of the corona radiata is a neural correlate of several, but not all, attention dimensions.

  8. The "sweet" side of the protein corona: effects of glycosylation on nanoparticle-cell interactions.

    Science.gov (United States)

    Wan, Sha; Kelly, Philip M; Mahon, Eugene; Stöckmann, Henning; Rudd, Pauline M; Caruso, Frank; Dawson, Kenneth A; Yan, Yan; Monopoli, Marco P

    2015-02-24

    The significance of a protein corona on nanoparticles in modulating particle properties and their biological interactions has been widely acknowledged. The protein corona is derived from proteins in biological fluids, many of which are glycosylated. To date, the glycans on the proteins have been largely overlooked in studies of nanoparticle-cell interactions. In this study, we demonstrate that glycosylation of the protein corona plays an important role in maintaining the colloidal stability of nanoparticles and influences nanoparticle-cell interactions. The removal of glycans from the protein corona enhances cell membrane adhesion and cell uptake of nanoparticles in comparison with the fully glycosylated form, resulting in the generation of a pro-inflammatory milieu by macrophages. This study highlights that the post-translational modification of proteins can significantly impact nanoparticle-cell interactions by modulating the protein corona properties.

  9. Dispersion of Nanoparticles in Different Media Importantly Determines the Composition of Their Protein Corona

    Science.gov (United States)

    Strojan, Klemen; Leonardi, Adrijana; Bregar, Vladimir B.; Križaj, Igor; Svete, Jurij; Pavlin, Mojca

    2017-01-01

    Protein corona of nanoparticles (NPs), which forms when these particles come in to contact with protein-containing fluids, is considered as an overlooked factor in nanomedicine. Through numerous studies it has been becoming increasingly evident that it importantly dictates the interaction of NPs with their surroundings. Several factors that determine the compositions of NPs protein corona have been identified in recent years, but one has remained largely ignored—the composition of media used for dispersion of NPs. Here, we determined the effect of dispersion media on the composition of protein corona of polyacrylic acid-coated cobalt ferrite NPs (PAA NPs) and silica NPs. Our results confirmed some of the basic premises such as NPs type-dependent specificity of the protein corona. But more importantly, we demonstrated the effect of the dispersion media on the protein corona composition. The differences between constituents of the media used for dispersion of NPs, such as divalent ions and macromolecules were responsible for the differences in protein corona composition formed in the presence of fetal bovine serum (FBS). Our results suggest that the protein corona composition is a complex function of the constituents present in the media used for dispersion of NPs. Regardless of the dispersion media and FBS concentration, majority of proteins from either PAA NPs or silica NPs coronas were involved in the process of transport and hemostasis. Interestingly, corona of silica NPs contained three complement system related proteins: complement factor H, complement C3 and complement C4 while PAA NPs bound only one immune system related protein, α-2-glycoprotein. Importantly, relative abundance of complement C3 protein in corona of silica NPs was increased when NPs were dispersed in NaCl, which further implies the relevance of dispersion media used to prepare NPs. PMID:28052135

  10. Dispersion of Nanoparticles in Different Media Importantly Determines the Composition of Their Protein Corona.

    Science.gov (United States)

    Strojan, Klemen; Leonardi, Adrijana; Bregar, Vladimir B; Križaj, Igor; Svete, Jurij; Pavlin, Mojca

    2017-01-01

    Protein corona of nanoparticles (NPs), which forms when these particles come in to contact with protein-containing fluids, is considered as an overlooked factor in nanomedicine. Through numerous studies it has been becoming increasingly evident that it importantly dictates the interaction of NPs with their surroundings. Several factors that determine the compositions of NPs protein corona have been identified in recent years, but one has remained largely ignored-the composition of media used for dispersion of NPs. Here, we determined the effect of dispersion media on the composition of protein corona of polyacrylic acid-coated cobalt ferrite NPs (PAA NPs) and silica NPs. Our results confirmed some of the basic premises such as NPs type-dependent specificity of the protein corona. But more importantly, we demonstrated the effect of the dispersion media on the protein corona composition. The differences between constituents of the media used for dispersion of NPs, such as divalent ions and macromolecules were responsible for the differences in protein corona composition formed in the presence of fetal bovine serum (FBS). Our results suggest that the protein corona composition is a complex function of the constituents present in the media used for dispersion of NPs. Regardless of the dispersion media and FBS concentration, majority of proteins from either PAA NPs or silica NPs coronas were involved in the process of transport and hemostasis. Interestingly, corona of silica NPs contained three complement system related proteins: complement factor H, complement C3 and complement C4 while PAA NPs bound only one immune system related protein, α-2-glycoprotein. Importantly, relative abundance of complement C3 protein in corona of silica NPs was increased when NPs were dispersed in NaCl, which further implies the relevance of dispersion media used to prepare NPs.

  11. Identification of Circulating miRNAs in a Mouse Model of Nerve Allograft Transplantation under FK506 Immunosuppression by Illumina Small RNA Deep Sequencing

    Directory of Open Access Journals (Sweden)

    Shao-Chun Wu

    2015-01-01

    Full Text Available Background. This study aimed to establish the expression profile of circulating microRNAs (miRNAs during nerve allotransplantation in the presence and absence of FK506 immunosuppression. Methods. A 1 cm BALB/c donor sciatic nerve graft was transplanted into the sciatic nerve gaps created in recipient C57BL/6 mice with or without daily FK506 immunosuppression [1 mg/(kg·d]. At 3, 7, and 14 d after nerve allotransplantation, serum samples were collected for miRNA expression analysis by Illumina small RNA deep sequencing. Results. Sequence analysis showed that the dominant size of circulating small RNAs after nerve allotransplantation was 22 nucleotides, followed by 23-nucleotide sequences. Nine upregulated circulating miRNAs (let-7e-5p, miR-101a-3p, miR-151-5p, miR-181a-5p, miR-204-5p, miR-340-5p, miR-381-3p, miR-411-5p, miR-9-5p, and miR-219-2-3p were identified at 3 d, but none was identified at 7 or 14 d. Among them, miR-9-5p had the highest fold-change of >50-fold, followed by miR-340-5p with 38.8-fold. The presence of these nine miRNAs was not significant at 7 and 14 d after nerve allotransplantation with or without immunosuppression, showing that these miRNAs are not ideal biomarkers for monitoring rejection of deep-buried nerve allografts, a response usually observed later. Conclusions. We identified nine upregulated circulating miRNAs, which may have a biological function, particularly during the early stages after nerve allotransplantation under FK506 immunosuppression.

  12. Interaction of N-FK5 and L-BAL35 optical glass with various carbide and other precision glass mold tooling

    Science.gov (United States)

    Koontz, E.; Wachtel, P.; Musgraves, J. David; Richardson, K.; Mourad, S.; Huber, M.; Kunz, A.; Forrer, M.

    2013-09-01

    Precision glass molding (PGM) is an optical manufacturing process used to hot press optical glass into a specified lens shape. This is done by taking the glass to a temperature above Tg and exerting force using an upper and lower mold. These molds will, together, give the pressed lens its shape. This study focuses on the high temperature interactions between the mold tooling material and two optical oxide glasses, Ohara's L-BAL35 and Schott's N-FK5. Flat molds were used to press flat glass work pieces at high temperature and force; key post process parameters such as sample and mold surface contamination using EDS and visible degradation via SEM were catalogued and analyzed. The molds used were bare tungsten carbide (WC) and silicon carbide (SiC) with an amorphous SiC chemical vapor deposition (CVD) coating. The results showed that raw WC molds suffered the most degradation including physical damage as well as chemical adherence and reaction. The Ti binder used in the WC as well as some the tungsten itself transferred to both glasses and caused a white reflective layer to appear on the molded glass surface. Severe damage was evident after only 2 pressing cycles with potassium from N-FK5 being the most prominent chemical contaminant. N-FK5 proved to be the more corrosive of the two glasses in all occasions. The SiC coated molds fared better in terms of degradation than the WC, however sticking of glass to mold was a problem.

  13. Marketingový mix 1. FK Příbram a návrhy na jeho zlepšení

    OpenAIRE

    Molnár, Jakub

    2012-01-01

    Title: Marketing mix of 1. FK Příbram and proposals for its improvement Targets: A thorough analysis of the individual parts of the sports club's marketing mix and then a proposal of suitable measures or processes that would lead to greater satisfaction of fans as a result of improving the marketing mix. Methods: An interview is used to find out information about the marketing mix. There is a case study used to analyze current marketing mix. Analysis of the conditions is carried out with the ...

  14. To the question on efficiency of rehabilitation sick of the chronic ischemic heart trouble with stable stenocardia II-IІІ FK of advanced age.

    Directory of Open Access Journals (Sweden)

    Kotko D.N.

    2010-11-01

    Full Text Available Methodical approaches of rehabilitation the patients of a chronic ischemic heart trouble to stable stenocardia II-IІІ FK are considered at senior 60 years to the chosen standard medical treatment in a combination to physical trainings. It is shown that inclusion of physical trainings in a complex of medical actions of patients increases efficiency of medicamentous treatment. It is defined that training programs should rest upon the general approaches of its implementation with a glance of age of sick.

  15. Concentrations of cyclosporin A and FK506 that inhibit IL-2 induction in human T cells do not affect TGF-beta1 biosynthesis, whereas higher doses of cyclosporin A trigger apoptosis and release of preformed TGF-beta1.

    Science.gov (United States)

    Minguillón, Jordi; Morancho, Beatriz; Kim, Seong-Jin; López-Botet, Miguel; Aramburu, José

    2005-05-01

    Cyclosporin A (CsA) and FK506 suppress T cell activation by inhibiting calcineurin and the calcineurin-dependent transcription factors nuclear factor of activated T cells (NFATc), which are central regulators of T cell function. It was reported that CsA up-regulated the transcription of transforming growth factor-beta1 (TGF-beta1) in lymphocytes and other cells and activated its promoter in A549 lung carcinoma cells, but the mechanisms involved are poorly understood, and it is unclear whether calcineurin plays any role. We have studied the regulation of TGF-beta1 in normal human lymphocytes and cell lines. In Jurkat T cells, the TGF-beta1 promoter was activated by calcineurin and NFATc and inhibited by CsA and FK506. However, the promoter was insensitive to both drugs in A549 cells. In human T cells preactivated with phytohemagglutinin, biosynthesis of TGF-beta1, induced by the T cell receptor (TCR) or the TGF-beta receptor, was not substantially affected by CsA and FK506 concentrations (< or = 1 microM) that effectively inhibited interleukin-2 production. However, pretreatment of fresh lymphocytes with CsA or FK506 during primary TCR stimulation reduced their production of TGF-beta1 during secondary TCR activation. Finally, high concentrations of CsA (10 microM), in the range attained in vivo in experiments in rodents, caused apoptosis in human T cells and the release of preformed, bioactive TGF-beta1. These effects are unlikely to owe to calcineurin inhibition, as they were not observed with FK506. Our results indicate that CsA and FK506 are not general inducers of TGF-beta1 biosynthesis but can cause different effects on TGF-beta1 depending on the cell type and concentrations used.

  16. Ground-based observation of emission lines from the corona of a red-dwarf star.

    Science.gov (United States)

    Schmitt, J H; Wichmann, R

    2001-08-02

    All 'solar-like' stars are surrounded by coronae, which contain magnetically confined plasma at temperatures above 106 K. (Until now, only the Sun's corona could be observed in the optical-as a shimmering envelope during a total solar eclipse.) As the underlying stellar 'surfaces'-the photospheres-are much cooler, some non-radiative process must be responsible for heating the coronae. The heating mechanism is generally thought to be magnetic in origin, but is not yet understood even for the case of the Sun. Ultraviolet emission lines first led to the discovery of the enormous temperature of the Sun's corona, but thermal emission from the coronae of other stars has hitherto been detectable only from space, at X-ray wavelengths. Here we report the detection of emission from highly ionized iron (Fe XIII at 3,388.1 A) in the corona of the red-dwarf star CN Leonis, using a ground-based telescope. The X-ray flux inferred from our data is consistent with previously measured X-ray fluxes, and the non-thermal line width of 18.4 km s-1 indicates great similarities between solar and stellar coronal heating mechanisms. The accessibility and spectral resolution (45,000) of the ground-based instrument are much better than those of X-ray satellites, so a new window to the study of stellar coronae has been opened.

  17. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts

    Science.gov (United States)

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-02-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 1017/m3 orders of magnitude, which is practicable for most discharging applications.

  18. Back corona enhanced organic film deposition inside an Atmospheric Pressure Weakly Ionized Plasma reactor

    Science.gov (United States)

    Islam, Rokibul; Xie, Shuzheng; Englund, Karl; Pedrow, Patrick

    2014-10-01

    A grounded screen with short needle-like protrusions has been designed to generate back corona in an Atmospheric Pressure Weakly Ionized Plasma (APWIP) reactor. The grounded screen with protrusions is placed downstream at a variable gap length from an array of needles that is energized with 60 Hz high voltage. The excitation voltage is in the range 0--10 kV RMS and the feed gas mixture consists of argon and acetylene. A Lecroy 9350AL 500 MHz digital oscilloscope is used to monitor the reactor voltage and current using a resistive voltage divider and a current viewing resistor, respectively. The current signal contains many positive and negative current pulses associated with corona discharge. Analysis of the current signal shows asymmetry between positive and negative corona discharge currents. Photographs show substantial back corona generated near the tips of the protrusions situated at the grounded screen. The back corona activates via bond scission acetylene radicals that are transported downstream to form a plasma-polymerized film on a substrate positioned downstream from the grounded screen. The oscillograms will be used to generate corona mode maps that show the nature of the corona discharge as a function of gap spacing, applied voltage and many other reactor parameters.

  19. Ex situ evaluation of the composition of protein corona of intravenously injected superparamagnetic nanoparticles in rats.

    Science.gov (United States)

    Sakulkhu, Usawadee; Maurizi, Lionel; Mahmoudi, Morteza; Motazacker, Mahdi; Vries, Marcel; Gramoun, Azza; Ollivier Beuzelin, Marie-Gabrielle; Vallée, Jean-Paul; Rezaee, Farhad; Hofmann, Heinrich

    2014-10-01

    It is now well recognized that the surfaces of nanoparticles (NPs) are coated with biomolecules (e.g., proteins) in a biological medium. Although extensive reports have been published on the protein corona at the surface of NPs in vitro, there are very few on the in vivo protein corona. The main reason for having very poor information regarding the protein corona in vivo is that separation of NPs from the in vivo environment has not been possible by using available techniques. Knowledge of the in vivo protein corona could lead to better understanding and prediction of the fate of NPs in vivo. Here, by using the unique magnetic properties of superparamagnetic iron oxide NPs (SPIONs), NPs were extracted from rat sera after in vivo interaction with the rat's physiological system. More specifically, the in vivo protein coronas of polyvinyl-alcohol-coated SPIONs with various surface charges are defined. The compositions of the corona at the surface of various SPIONs and their effects on the biodistribution of SPIONs were examined and compared with the corona composition of particles incubated for the same time in rat serum.

  20. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts.

    Science.gov (United States)

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-12-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 10(17)/m(3) orders of magnitude, which is practicable for most discharging applications.

  1. Predicting Cell Association of Surface-Modified Nanoparticles Using Protein Corona Structure - Activity Relationships (PCSAR).

    Science.gov (United States)

    Kamath, Padmaja; Fernandez, Alberto; Giralt, Francesc; Rallo, Robert

    2015-01-01

    Nanoparticles are likely to interact in real-case application scenarios with mixtures of proteins and biomolecules that will absorb onto their surface forming the so-called protein corona. Information related to the composition of the protein corona and net cell association was collected from literature for a library of surface-modified gold and silver nanoparticles. For each protein in the corona, sequence information was extracted and used to calculate physicochemical properties and statistical descriptors. Data cleaning and preprocessing techniques including statistical analysis and feature selection methods were applied to remove highly correlated, redundant and non-significant features. A weighting technique was applied to construct specific signatures that represent the corona composition for each nanoparticle. Using this basic set of protein descriptors, a new Protein Corona Structure-Activity Relationship (PCSAR) that relates net cell association with the physicochemical descriptors of the proteins that form the corona was developed and validated. The features that resulted from the feature selection were in line with already published literature, and the computational model constructed on these features had a good accuracy (R(2)LOO=0.76 and R(2)LMO(25%)=0.72) and stability, with the advantage that the fingerprints based on physicochemical descriptors were independent of the specific proteins that form the corona.

  2. Protein corona composition does not accurately predict hematocompatibility of colloidal gold nanoparticles.

    Science.gov (United States)

    Dobrovolskaia, Marina A; Neun, Barry W; Man, Sonny; Ye, Xiaoying; Hansen, Matthew; Patri, Anil K; Crist, Rachael M; McNeil, Scott E

    2014-10-01

    Proteins bound to nanoparticle surfaces are known to affect particle clearance by influencing immune cell uptake and distribution to the organs of the mononuclear phagocytic system. The composition of the protein corona has been described for several types of nanomaterials, but the role of the corona in nanoparticle biocompatibility is not well established. In this study we investigate the role of nanoparticle surface properties (PEGylation) and incubation times on the protein coronas of colloidal gold nanoparticles. While neither incubation time nor PEG molecular weight affected the specific proteins in the protein corona, the total amount of protein binding was governed by the molecular weight of PEG coating. Furthermore, the composition of the protein corona did not correlate with nanoparticle hematocompatibility. Specialized hematological tests should be used to deduce nanoparticle hematotoxicity. From the clinical editor: It is overall unclear how the protein corona associated with colloidal gold nanoparticles may influence hematotoxicity. This study warns that PEGylation itself may be insufficient, because composition of the protein corona does not directly correlate with nanoparticle hematocompatibility. The authors suggest that specialized hematological tests must be used to deduce nanoparticle hematotoxicity.

  3. Unveiling the in Vivo Protein Corona of Circulating Leukocyte-like Carriers.

    Science.gov (United States)

    Corbo, Claudia; Molinaro, Roberto; Taraballi, Francesca; Toledano Furman, Naama E; Hartman, Kelly A; Sherman, Michael B; De Rosa, Enrica; Kirui, Dickson K; Salvatore, Francesco; Tasciotti, Ennio

    2017-03-10

    Understanding interactions occurring at the interface between nanoparticles and biological components is an urgent challenge in nanomedicine due to their effect on the biological fate of nanoparticles. After the systemic injection of nanoparticles, a protein corona constructed by blood components surrounds the carrier's surface and modulates its pharmacokinetics and biodistribution. Biomimicry-based approaches in nanotechnology attempt to imitate what happens in nature in order to transfer specific natural functionalities to synthetic nanoparticles. Several biomimetic formulations have been developed, showing superior in vivo features as a result of their cell-like identity. We have recently designed biomimetic liposomes, called leukosomes, which recapitulate the ability of leukocytes to target inflamed endothelium and escape clearance by the immune system. To gain insight into the properties of leukosomes, we decided to investigate their protein corona in vivo. So far, most information about the protein corona has been obtained using in vitro experiments, which have been shown to minimally reproduce in vivo phenomena. Here we directly show a time-dependent quantitative and qualitative analysis of the protein corona adsorbed in vivo on leukosomes and control liposomes. We observed that leukosomes absorb fewer proteins than liposomes, and we identified a group of proteins specifically adsorbed on leukosomes. Moreover, we hypothesize that the presence of macrophage receptors on leukosomes' surface neutralizes their protein corona-meditated uptake by immune cells. This work unveils the protein corona of a biomimetic carrier and is one of the few studies on the corona performed in vivo.

  4. Recent Studies of the Behavior of the Sun's White-Light Corona Over Time

    Science.gov (United States)

    SaintCyr, O. C.; Young, D. E.; Pesnell, W. D.; Lecinski, A.; Eddy, J.

    2008-01-01

    Predictions of upcoming solar cycles are often related to the nature and dynamics of the Sun's polar magnetic field and its influence on the corona. For the past 30 years we have a more-or-less continuous record of the Sun's white-light corona from groundbased and spacebased coronagraphs. Over that interval, the large scale features of the corona have varied in what we now consider a 'predictable' fashion--complex, showing multiple streamers at all latitudes during solar activity maximum; and a simple dipolar shape aligned with the rotational pole during solar minimum. Over the past three decades the white-light corona appears to be a better indicator of 'true' solar minimum than sunspot number since sunspots disappear for months (even years) at solar minimum. Since almost all predictions of the timing of the next solar maximum depend on the timing of solar minimum, the white-light corona is a potentially important observational discriminator for future predictors. In this contribution we describe recent work quantifying the large-scale appearance of the Sun's corona to correlate it with the sunspot record, especially around solar minimum. These three decades can be expanded with the HAO archive of eclipse photographs which, although sparse compared to the coronagraphic coverage, extends back to 1869. A more extensive understanding of this proxy would give researchers confidence in using the white-light corona as an indicator of solar minimum conditions.

  5. Multiphysics simulation of corona discharge induced ionic wind

    CERN Document Server

    Cagnoni, Davide; Christen, Thomas; de Falco, Carlo; Parolini, Nicola; Stevanović, Ivica

    2013-01-01

    Ionic wind devices or electrostatic fluid accelerators are becoming of increasing interest as tools for thermal management, in particular for semiconductor devices. In this work, we present a numerical model for predicting the performance of such devices, whose main benefit is the ability to accurately predict the amount of charge injected at the corona electrode. Our multiphysics numerical model consists of a highly nonlinear strongly coupled set of PDEs including the Navier-Stokes equations for fluid flow, Poisson's equation for electrostatic potential, charge continuity and heat transfer equations. To solve this system we employ a staggered solution algorithm that generalizes Gummel's algorithm for charge transport in semiconductors. Predictions of our simulations are validated by comparison with experimental measurements and are shown to closely match. Finally, our simulation tool is used to estimate the effectiveness of the design of an electrohydrodynamic cooling apparatus for power electronics applicat...

  6. An efficient algorithm for corona simulation with complex chemical models

    Science.gov (United States)

    Villa, Andrea; Barbieri, Luca; Gondola, Marco; Leon-Garzon, Andres R.; Malgesini, Roberto

    2017-05-01

    The simulation of cold plasma discharges is a leading field of applied sciences with many applications ranging from pollutant control to surface treatment. Many of these applications call for the development of novel numerical techniques to implement fully three-dimensional corona solvers that can utilize complex and physically detailed chemical databases. This is a challenging task since it multiplies the difficulties inherent to a three-dimensional approach by the complexity of databases comprising tens of chemical species and hundreds of reactions. In this paper a novel approach, capable of reducing significantly the computational burden, is developed. The proposed method is based on a proper time stepping algorithm capable of decomposing the original problem into simpler ones: each of them has then been tackled with either finite element, finite volume or ordinary differential equations solvers. This last solver deals with the chemical model and its efficient implementation is one of the main contributions of this work.

  7. Plasma compression in magnetic reconnection regions in the solar corona

    CERN Document Server

    Provornikova, Elena; Lukin, Vyacheslav S

    2016-01-01

    It has been proposed that particles bouncing between magnetized flows converging in a reconnection region can be accelerated by the first order Fermi mechanism. Analytical considerations of this mechanism have shown that the spectral index of accelerated particles is related to the total plasma compression within the reconnection region similarly to the case of diffusive shock acceleration mechanism. As a first step to investigate the efficiency of Fermi acceleration in reconnection regions in producing hard energy spectra of particles in the solar corona, we explore the degree of plasma compression that can be achieved at reconnection sites. In particular, we aim to determine the conditions for the strong compressions to form. Using a two-dimensional resistive MHD numerical model we consider a set of magnetic field configurations where magnetic reconnection can occur including a Harris current sheet, a force-free current sheet, and two merging flux ropes. Plasma parameters are taken to be characteristic of t...

  8. Charge dynamic characteristics in corona-charged polytetrafluoroethylene film electrets

    Institute of Scientific and Technical Information of China (English)

    陈钢进; 肖慧明; 朱春凤

    2004-01-01

    In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and thermal stimulating surface-potential decay measurements. The results showed that the initial surface potential, whether positively or negatively charging, is much higher in non-porous PTFE than in porous PTFE. For porous film the value of initial sur-face potentials increases with increase of film thickness. Higher charging temperature can remarkably improve charge stability. The charge dynamics are correlated to materials microstructure according to their scanning electron micrographs.For non-porous PTFE films, polarizability change of C-F bonds is the main origin of electret charges; but for porous PTFE film a large number of bulk and interface type traps are expected because of the greater area of interface and higher crys-tallinity.

  9. Charge dynamic characteristics in corona-charged polytetrafluoroethylene film electrets

    Institute of Scientific and Technical Information of China (English)

    陈钢进; 肖慧明; 朱春凤

    2004-01-01

    In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and thermal stimulating surface-potential decay measurements. The results showed that the initial surface potential, whether positively or negatively charging, is much higher in non-porous PTFE than in porous PTFE. For porous film the value of initial surface potentials increases with increase of film thickness. Higher charging temperature can remarkably improve charge stability. The charge dynamics are correlated to materials microstructure according to their scanning electron micrographs.For non-porous PTFE films, polarizability change of C-F bonds is the main origin of electret charges; but for porous PTFE film a large number of bulk and interface type traps are expected because of the greater area of interface and higher crystallinity.

  10. Characterization of the slow wind in the outer corona

    CERN Document Server

    Abbo, Lucia; Mikić, Zoran; Linker, Jon A; Riley, Pete; Lionello, Roberto; 10.1016/j.asr.2010.08.008

    2010-01-01

    The study concerns the streamer belt observed at high spectral resolution during the minimum of solar cycle 22 with the Ultraviolet Coronagraph Spectrometer (UVCS) onboard SOHO. On the basis of a spectroscopic analysis of the O VI doublet, the solar wind plasma parameters are inferred in the extended corona. The analysis accounts for the coronal magnetic topology, extrapolated through a 3D magneto-hydrodynamic model, in order to define the streamer boundary and to analyse the edges of coronal holes. The results of the analysis allow an accurate identification of the source regions of the slow coronal wind that are confirmed to be along the streamer boundary in the open magnetic field region.

  11. Corona discharge ionization of paracetamol molecule: Peak assignment

    Science.gov (United States)

    Bahrami, H.; Farrokhpour, H.

    2015-01-01

    Ionization of paracetamol was investigated using ion mobility spectrometry equipped with a corona discharge ionization source. The measurements were performed in the positive ion mode and three peaks were observed in the ion mobility spectrum. Experimental evidence and theoretical calculations were used to correlate the peaks to related ionic species of paracetamol. Two peaks were attributed to protonated isomers of paracetamol and the other peak was attributed to paracetamol fragment ions formed by dissociation of the N-C bond after protonation of the nitrogen atom. It was observed that three sites of paracetamol compete for protonation and their relative intensities, depending on the sample concentration. The ratio of ion products could be predicted from the internal proton affinity of the protonation sites at each concentration.

  12. Naphthalene decomposition in a DC corona radical shower discharge

    Institute of Scientific and Technical Information of China (English)

    Ming-jiang NI; Xu SHEN; Xiang GAO; Zu-liang WU; Hao LU; Zhong-shan LI; Zhong-yang LUO; Ke-fa CEN

    2011-01-01

    The naphthalene decomposition in a corona radical shower discharge (CRS) was investigated, with attention paid to the influences of voltage and initial naphthalene density. The OH emission spectra were investigated so as to know the naphthalene decomposing process. The by-products were analyzed and a decomposing theory in discharge was proposed. The results showed that higher voltage and relative humidity were effective on decomposition. The initial concentration affected the decomposing efficiency of naphthalene. When the mitial naphthalene density was 17 mg/m3, the decomposition rate was found to be 70% under 14 kV. The main by-products were carbon dioxide and water. However, a small amount of carbonic oxide, 1, 2-ethanediol and acetaldehyde were found due to the incomplete oxidization.

  13. A corona discharge initiated electrochemical electrospray ionization technique.

    Science.gov (United States)

    Lloyd, John R; Hess, Sonja

    2009-11-01

    We report here the development of a corona discharge (CD) initiated electrochemical (EC) electrospray ionization (ESI) technique using a standard electrospray ion source. This is a new ionization technique distinct from ESI, electrochemistry inherent to ESI, APCI, and techniques using hydroxyl radicals produced under atmospheric pressure conditions. By maximizing the observable CD at the tip of a stainless steel ESI capillary, efficient electrochemical oxidation of electrochemically active compounds is observed. For electrochemical oxidation to be observed, the ionization potential of the analyte must be lower than Fe. Ferrocene labeled compounds were chosen as the electrochemically active moiety. The electrochemical cell in the ESI source was robust, and generated ions with selectivity according to the ionization potential of the analytes and up to zeptomolar sensitivity. Our results indicate that CD initiated electrochemical ionization has the potential to become a powerful technique to increase the dynamic range, sensitivity, and selectivity of ESI experiments.

  14. Partial oxidation of methane by pulsed corona discharges

    Science.gov (United States)

    Hoeben, W. F. L. M.; Boekhoven, W.; Beckers, F. J. C. M.; van Heesch, E. J. M.; Pemen, A. J. M.

    2014-09-01

    Pulsed corona-induced partial oxidation of methane in humid oxygen or carbon dioxide atmospheres has been investigated for future fuel synthesis applications. The obtained product spectrum is wide, i.e. saturated, unsaturated and oxygen-functional hydrocarbons. The generally observed methane conversion levels are 6-20% at a conversion efficiency of about 100-250 nmol J-1. The main products are ethane, ethylene and acetylene. Higher saturated hydrocarbons up to C6 have been detected. The observed oxygen-functional hydrocarbons are methanol, ethanol and lower concentrations of aldehydes, ketones, dimethylether and methylformate. Methanol seems to be exclusively produced with CH4/O2 mixtures at a maximum production efficiency of 0.35 nmol J-1. CH4/CO2 mixtures appear to yield higher hydrocarbons. Carboxylic acids appear to be mainly present in the aqueous reactor phase, possibly together with higher molecular weight species.

  15. Alfvén waves in the structured solar corona

    Science.gov (United States)

    Cally, Paul S.

    2017-04-01

    A simple model of a periodic ensemble of closely packed flux tubes, sitting atop a vertically stratified layer, reveals that an incident fast wave from below preferentially converts almost immediately to Alfvén waves in the flux tubes, with kink waves restricted to at most a very few Fourier modes. This suggests that observations of coronal kink modes in such structured systems may greatly underestimate the net wave-energy flux being transported into and through the corona, much of which may reside in harder-to-observe Alfvén waves. The processes of mode conversion/resonant absorption and Alfvén phase mixing are implicated. It is suggested that the Sun's internal p-mode field - the 5-min oscillations - may contribute substantially to the process by supplying incident fast waves in the chromosphere that scatter and mode-convert in the tube ensemble.

  16. Multiphysics simulation of corona discharge induced ionic wind

    Energy Technology Data Exchange (ETDEWEB)

    Cagnoni, Davide [ABB Switzerland Ltd., Corporate Research, CH-5405 Baden-Dättwil (Switzerland); MOX - Dipartimento di Matematica “F. Brioschi,” Politecnico di Milano, 20133 Milano (Italy); Agostini, Francesco; Christen, Thomas [ABB Switzerland Ltd., Corporate Research, CH-5405 Baden-Dättwil (Switzerland); Parolini, Nicola [MOX - Dipartimento di Matematica “F. Brioschi,” Politecnico di Milano, 20133 Milano (Italy); Stevanović, Ivica [ABB Switzerland Ltd., Corporate Research, CH-5405 Baden-Dättwil (Switzerland); Laboratory of Electromagnetics and Acoustics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Falco, Carlo de [MOX - Dipartimento di Matematica “F. Brioschi,” Politecnico di Milano, 20133 Milano (Italy); CEN - Centro Europeo di Nanomedicina, 20133 Milano (Italy)

    2013-12-21

    Ionic wind devices or electrostatic fluid accelerators are becoming of increasing interest as tools for thermal management, in particular for semiconductor devices. In this work, we present a numerical model for predicting the performance of such devices; its main benefit is the ability to accurately predict the amount of charge injected from the corona electrode. Our multiphysics numerical model consists of a highly nonlinear, strongly coupled set of partial differential equations including the Navier-Stokes equations for fluid flow, Poisson's equation for electrostatic potential, charge continuity, and heat transfer equations. To solve this system we employ a staggered solution algorithm that generalizes Gummel's algorithm for charge transport in semiconductors. Predictions of our simulations are verified and validated by comparison with experimental measurements of integral physical quantities, which are shown to closely match.

  17. Magnetic Jam in the Corona of the Sun

    CERN Document Server

    Chen, F; Bingert, S; Cheung, M C M

    2015-01-01

    The outer solar atmosphere, the corona, contains plasma at temperatures of more than a million K, more than 100 times hotter that solar surface. How this gas is heated is a fundamental question tightly interwoven with the structure of the magnetic field in the upper atmosphere. Conducting numerical experiments based on magnetohydrodynamics we account for both the evolving three-dimensional structure of the atmosphere and the complex interaction of magnetic field and plasma. Together this defines the formation and evolution of coronal loops, the basic building block prominently seen in X-rays and extreme ultraviolet (EUV) images. The structures seen as coronal loops in the EUV can evolve quite differently from the magnetic field. While the magnetic field continuously expands as new magnetic flux emerges through the solar surface, the plasma gets heated on successively emerging fieldlines creating an EUV loop that remains roughly at the same place. For each snapshot the EUV images outline the magnetic field, bu...

  18. Corona-induced electrohydrodynamic instabilities in low conducting liquids

    Energy Technology Data Exchange (ETDEWEB)

    Vega, F.; Perez, A.T. [Depto. Electronica y Electromagnetismo, Facultad de Fisica, Universidad de Sevilla, Avda. Reina Mercedes, s/n. 41012, Sevilla (Spain)

    2003-06-01

    The rose-window electrohydrodynamic (EHD) instability has been observed when a perpendicular field with an additional unipolar ion injection is applied onto a low conducting liquid surface. This instability has a characteristic pattern with cells five to 10 times greater than those observed in volume instabilities caused by unipolar injection. We have used corona discharge from a metallic point to perform some measurements of the rose-window instability in low conducting liquids. The results are compared to the linear theoretical criterion for an ohmic liquid. They confirmed that the minimum voltage for this instability is much lower than that for the interfacial instability in high conducting liquids. This was predicted theoretically in the dependence of the critical voltage as a function of the non-dimensional conductivity. It is shown that in a non-ohmic liquid the rose window appears as a secondary instability after the volume instability. (orig.)

  19. Modeling X-ray emission from stellar coronae

    CERN Document Server

    Gregory, S G; Argiroffi, C; Donati, J -F

    2008-01-01

    By extrapolating from observationally derived surface magnetograms of low-mass stars we construct models of their coronal magnetic fields and compare the 3D field geometry with axial multipoles. AB Dor, which has a radiative core, has a very complex field, whereas V374 Peg, which is completely convective, has a simple dipolar field. We calculate global X-ray emission measures assuming that the plasma trapped along the coronal loops is in hydrostatic equilibrium and compare the differences between assuming isothermal coronae, or by considering a loop temperature profiles. Our preliminary results suggest that the non-isothermal model works well for the complex field of AB Dor, but not for the simple field of V374 Peg.

  20. Experimental optimization of an electric blower by corona wind

    Energy Technology Data Exchange (ETDEWEB)

    Rashkovan, A.; Sher, E.; Kalman, H. [Ben-Gurion University of the Negev, Beer Sheva (Israel). Dept. of Mechanical Engineering

    2002-10-01

    The effect of corona wind produced by stretched steel wire and two copper wings on the heat transfer from a heated horizontal plate was investigated experimentally. Although in such an arrangement the heat transfer augmentation is expected to be lower, some advantages may be postulated. In such a construction, the plate to be cooled is not a part of the wind generation system, it is not charged, the electrical field next to it is negligible, and it may be constructed from non-metallic materials. In the course of the study, optimal geometric parameters of the electric blower together with optimal value of high voltage supply have been established. Under these optimal conditions, augmentation by three times of the heat transfer coefficient over that for the natural convection has been achieved. (author)

  1. Corona discharge ion mobility spectrometry at reduced pressures

    Science.gov (United States)

    Tabrizchi, Mahmoud; Rouholahnejad, Fereshteh

    2004-11-01

    Ion mobility spectrometers (IMSs) normally operate at ambient pressure. In this work an IMS cell has been designed and constructed to allow the pressure to be reduced inside the IMS cell. In this cell, corona discharge was employed as the ionization source. Reducing pressure affected both the discharge and the performance of the IMS. The discharge current was observed to increase with reducing pressure while the ignition potential decreased. The ion current received at the collector plate was also increased about 50 times when the pressure was reduced from ambient pressure to 15 Torr. The higher ion current can lead to an extended dynamic range. IMS spectra were recorded at various pressures and the results show that the drift times shift perfectly linear with pressure. This suggests that unlike temperature, pressure correction for ion mobility spectra is as simple as multiplying the drift times by a factor of 760/P.

  2. Dynamics of nanoparticle-protein corona complex formation: analytical results from population balance equations.

    Directory of Open Access Journals (Sweden)

    Faryad Darabi Sahneh

    Full Text Available BACKGROUND: Nanoparticle-protein corona complex formation involves absorption of protein molecules onto nanoparticle surfaces in a physiological environment. Understanding the corona formation process is crucial in predicting nanoparticle behavior in biological systems, including applications of nanotoxicology and development of nano drug delivery platforms. METHOD: This paper extends the modeling work in to derive a mathematical model describing the dynamics of nanoparticle corona complex formation from population balance equations. We apply nonlinear dynamics techniques to derive analytical results for the composition of nanoparticle-protein corona complex, and validate our results through numerical simulations. RESULTS: The model presented in this paper exhibits two phases of corona complex dynamics. In the first phase, proteins rapidly bind to the free surface of nanoparticles, leading to a metastable composition. During the second phase, continuous association and dissociation of protein molecules with nanoparticles slowly changes the composition of the corona complex. Given sufficient time, composition of the corona complex reaches an equilibrium state of stable composition. We find analytical approximate formulae for metastable and stable compositions of corona complex. Our formulae are very well-structured to clearly identify important parameters determining corona composition. CONCLUSION: The dynamics of biocorona formation constitute vital aspect of interactions between nanoparticles and living organisms. Our results further understanding of these dynamics through quantitation of experimental conditions, modeling results for in vitro systems to better predict behavior for in vivo systems. One potential application would involve a single cell culture medium related to a complex protein medium, such as blood or tissue fluid.

  3. Effect of oxygen on NOx removal in corona discharge field: NOx behavior without a reducing agent

    Energy Technology Data Exchange (ETDEWEB)

    M. Arai; M. Saito; S. Yoshinaga [Gunma University, Gunma (Japan). Department of Mechanical System Engineering

    2004-10-01

    A DeNOx process using a DC corona discharge was investigated experimentally. A mixture system of N{sub 2}/O{sub 2}/NO was used as a test gas. The compositions such as NO, NO{sub 2}, N{sub 2}O and so on were analyzed with Fourier transform infrared spectroscopy and an NOx meter. It was found that the characteristics of NO removal by corona discharge differed remarkably whether or not oxygen exists in the mixture. In regard to the spectrum of light emission from the corona discharge in N{sub 2} atmosphere or N{sub 2}/O{sub 2} mixture, some N{sub 2} bands were detected. N{sub 2} dissociation into atomic N and N{sub 2} radical in the corona discharge field was conjectured. Furthermore, ozone was yielded by the corona discharge in the case of the N{sub 2}/O{sub 2} mixture. Ozone gas from an ozonizer was added into the N{sub 2}/O{sub 2} mixture without corona discharge to investigate the effect of O{sub 3} on the characteristics of NOx removal by corona discharge. In the case of the N{sub 2}/NO mixture, the process of NO reduction was mainly controlled by N{sub 2} radicals excited by the corona discharge. On the other hand, in the case of the N{sub 2}/O{sub 2}/NO mixture, NO was oxidized by ozone generated from the corona discharge and converted to NO{sub 2} and N{sub 2}O{sub 5}.

  4. Centrally Concentrated X-Ray Radiation from an Extended Accreting Corona in Active Galactic Nuclei

    Science.gov (United States)

    Liu, B. F.; Taam, Ronald E.; Qiao, Erlin; Yuan, Weimin

    2017-10-01

    The X-ray emission from bright active galactic nuclei (AGNs) is believed to originate in a hot corona lying above a cold, geometrically thin accretion disk. A highly concentrated corona located within ∼10 gravitational radii above the black hole is inferred from observations. Based on the accretion of interstellar medium/wind, a disk corona model has been proposed in which the corona is well coupled to the disk by radiation, thermal conduction, as well as by mass exchange. Such a model avoids artificial energy input to the corona and has been used to interpret the spectral features observed in AGN. In this work, it is shown that the bulk emission size of the corona is very small for the extended accretion flow in our model. More than 80% of the hard X-ray power is emitted from a small region confined within 10 Schwarzschild radii around a non-spinning black hole, which is expected to be even smaller accordingly for a spinning black hole. Here, the corona emission is more extended at higher Eddington ratios. The compactness parameter of the corona, l=\\tfrac{L}{R}\\tfrac{{σ }{{T}}}{{m}{{e}}{c}3}, is shown to be in the range of 1–33 for Eddington ratios of 0.02–0.1. Combined with the electron temperature in the corona, this indicates that electron–positron pair production is not dominant in this regime. A positive relation between the compactness parameter and photon index is also predicted. By comparing the above model predictions with observational features, we find that the model is in agreement with observations.

  5. Distribution of electric currents in sunspots from photosphere to corona

    Energy Technology Data Exchange (ETDEWEB)

    Gosain, Sanjay [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Démoulin, Pascal [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon Principal Cedex (France); López Fuentes, Marcelo [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC. 67, Suc. 28 Buenos Aires 1428 (Argentina)

    2014-09-20

    We present a study of two regular sunspots that exhibit nearly uniform twist from the photosphere to the corona. We derive the twist parameter in the corona and in the chromosphere by minimizing the difference between the extrapolated linear force-free field model field lines and the observed intensity structures in the extreme-ultraviolet images of the Sun. The chromospheric structures appear more twisted than the coronal structures by a factor of two. Further, we derive the vertical component of electric current density, j{sub z} , using vector magnetograms from the Hinode Solar Optical Telescope (SOT). The spatial distribution of j{sub z} has a zebra pattern of strong positive and negative values owing to the penumbral fibril structure resolved by Hinode/SOT. This zebra pattern is due to the derivative of the horizontal magnetic field across the thin fibrils; therefore, it is strong and masks weaker currents that might be present, for example, as a result of the twist of the sunspot. We decompose j{sub z} into the contribution due to the derivatives along and across the direction of the horizontal field, which follows the fibril orientation closely. The map of the tangential component has more distributed currents that are coherent with the chromospheric and coronal twisted structures. Moreover, it allows us to map and identify the direct and return currents in the sunspots. Finally, this decomposition of j{sub z} is general and can be applied to any vector magnetogram in order to better identify the weaker large-scale currents that are associated with coronal twisted/sheared structures.

  6. Buoyant subduction on Venus: Implications for subduction around coronae

    Science.gov (United States)

    Burt, J. D.; Head, J. W.

    1993-03-01

    Potentially low lithospheric densities, caused by high Venus surface and perhaps mantle temperatures, could inhibit the development of negative buoyancy-driven subduction and a global system of plate tectonics/crustal recycling on that planet. No evidence for a global plate tectonic system was found so far, however, specific features strongly resembling terrestrial subduction zones in planform and topographic cross-section were described, including trenches around large coronae and chasmata in eastern Aphrodite Terra. The cause for the absence, or an altered expression, of plate tectonics on Venus remains to be found. Slab buoyancy may play a role in this difference, with higher lithospheric temperatures and a tendency toward positive buoyancy acting to oppose the descent of slabs and favoring under thrusting instead. The effect of slab buoyancy on subduction was explored and the conditions which would lead to under thrusting versus those allowing the formation of trenches and self-perpetuating subduction were defined. Applying a finite element code to assess the effects of buoyant forces on slabs subducting into a viscous mantle, it was found that mantle flow induced by horizontal motion of the convergent lithosphere greatly influences subduction angle, while buoyancy forces produce a lesser effect. Induced mantle flow tends to decrease subduction angle to near an under thrusting position when the subducting lithosphere converges on a stationary overriding lithosphere. When the overriding lithosphere is in motion, as in the case of an expanding corona, subduction angles are expected to increase. An initial stage involved estimating the changes in slab buoyancy due to slab healing and pressurization over the course of subduction. Modeling a slab, descending at a fixed angle and heated by conduction, radioactivity, and the heat released in phase changes, slab material density changes due to changing temperature, phase, and pressure were derived.

  7. WHAT IS THE SHELL AROUND R CORONAE BOREALIS?

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, Edward J.; Clayton, Geoffrey C.; Marcello, Dominic C. [Dept. of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Lockman, Felix J., E-mail: emonti2@lsu.edu, E-mail: gclayton@fenway.phys.lsu.edu, E-mail: dmarce1@tigers.lsu.edu, E-mail: jlockman@nrao.edu [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States)

    2015-07-15

    The hydrogen-deficient, carbon-rich R Coronae Borealis (RCB) stars are known for being prolific producers of dust which causes their large iconic declines in brightness. Several RCB stars, including R Coronae Borealis (R CrB), itself, have large extended dust shells seen in the far-infrared. The origin of these shells is uncertain but they may give us clues to the evolution of the RCB stars. The shells could form in three possible ways. (1) They are fossil Planetary Nebula (PN) shells, which would exist if RCB stars are the result of a final, helium-shell flash, (2) they are material left over from a white-dwarf (WD) merger event which formed the RCB stars, or (3) they are material lost from the star during the RCB phase. Arecibo 21 cm observations establish an upper limit on the column density of H I in the R CrB shell implying a maximum shell mass of ≲0.3 M{sub ☉}. A low-mass fossil PN shell is still a possible source of the shell although it may not contain enough dust. The mass of gas lost during a WD merger event will not condense enough dust to produce the observed shell, assuming a reasonable gas-to-dust ratio. The third scenario where the shell around R CrB has been produced during the star’s RCB phase seems most likely to produce the observed mass of dust and the observed size of the shell. But this means that R CrB has been in its RCB phase for ∼10{sup 4} years.

  8. Changes in lymphocyte phenotype and increased skin allograft survival after FTY720+FK506 therapy Modificação do fenótipo linfocitário e aumento da sobrevida do enxerto de pele após a terapia com FTY720 + FK506

    Directory of Open Access Journals (Sweden)

    Camila T. Lopes

    2008-01-01

    Full Text Available The development of new drugs to be associated with calcineurin inhibitors and promote additional immunosuppression with fewer side effects is the goal in transplantation. FTY720 is a new synthetic compound which presents immunomodulatory properties which are not fully understood. It has been reported that the main mechanism of action of FTY720 is to reduce the peripheral lymphocyte count by redirecting these cells toward secondary lymphoid organs. Skin allograft transplantation in a fully mismatched strain combination was used to investigate the potential of FTY720 alone or in combination with a calcineurin inhibitor - FK506 - in preventing rejection. The number and phenotype of immune system cells was also evaluated. FTY720 alone or in combination with FK506 provided significant skin allograft survival. FTY720+FK506 therapy was associated with decreases of total lymphocyte numbers in spleen and blood, and increases in apoptosis levels in splenocytes. In FTY720 isolated treatment, a significant decrease in the CD4 expression and significantly lower expressions of MHC II and ICAM-1 molecules were observed in spleen lymphocytes. Despite of allograft survival being the same in both FTY720 and FTY720+FK506 treated groups, the association of drugs was associated with the absence of macroscopic skin necrosis for a longer period than the other treatments (FTY720, FK506 and histology showed less cell infiltration. Our results suggest that a decrease of effector T cells due to elevated levels of apoptosis and impairment in the appearance of antigens were events associated with FTY720+FK506 administration.O objetivo na área dos transplantes é o desenvolvimento de novas drogas que possam ser associadas a inibidores da calcineurina para evitar o processo de rejeição e causar menos efeitos colaterais. FTY720 é um novo composto sintético que apresenta propriedades imunomoduladoras não completamente elucidadas. Foi relatado que o principal mecanismo de

  9. Pseudoscalar meson decay constants f_K, f_D and f_Ds, from Nf=2 twisted mass Lattice QCD

    CERN Document Server

    Blossier, B; Simula, S; Tarantino, C

    2008-01-01

    We present the results of a lattice QCD calculation of the pseudoscalar meson decay constants f_K, f_D and f_Ds, performed with N_f=2 dynamical fermions. The simulation is carried out with the tree-level improved Symanzik gauge action and with the twisted mass fermionic action at maximal twist. With respect to our previous study (0709.4574 [hep-lat]), here we have analysed data at three values of the lattice spacing (a=0.10 fm, 0.09 fm, 0.07 fm) and performed the continuum limit, and we have included at a=0.09 fm data with a lighter quark mass (m_pi = 260 MeV) and a larger volume (L = 2.7 fm), thus having at each lattice spacing L >= 2.4 fm and m_pi*L >= 3.6. Our result for the kaon decay constant is f_K=(157.5 +- 0.8|_{stat.} +- 3.3|_{syst.}) MeV and for the ratio f_K/f_pi=1.205 +- 0.006|_{stat.} +- 0.025|_{syst.}, in good agreement with the other N_f=2 and N_f=2+1 lattice calculations. For the D and D_s meson decay constants we obtain f_D=(205 +- 7|_{stat.} +- 7|_{syst.}) MeV, in good agreement with the CLE...

  10. Large-scale volcanism associated with coronae on Venus - Implications for formation and evolution

    Science.gov (United States)

    Roberts, Kari M.; Head, James W.

    1993-01-01

    Large-scale volcanism, in the form of areally extensive flow fields, is a previously unrecognized important aspect of the evolution of at least 41 percent of all coronae on Venus. The timing and scale of many coronae flow fields is consistent with an origin due to the arrival and pressure-release melting of material in the head of a mantle plume or diapir. The production of voluminous amounts of volcanism at some coronae is proposed to be the result of larger plume size and/or the intersection of mantle upwellings with regions of lithospheric extension and rifting.

  11. Create 2D mobile games with Corona SDK for iOS and Android

    CERN Document Server

    Mekersa, David

    2015-01-01

    Corona SDK is one of the most powerful tools used to create games and apps for mobile devices.The market requires speed; new developers need to operate quickly and efficiently. Create 2D Mobile Games with Corona SDK gives you the tools needed to master Corona - even within the framework of professional constraints. A must-read guide, this book gives you fast, accurate tips to learn the programming language necessary to create games. Read it sequentially or as an FAQ and you will have the tools you need to create any base game before moving on to advanced topics. The tutorial-based format:Conta

  12. Corona Formation and Heat Loss on Venus by Coupled Upwelling and Delamination

    Science.gov (United States)

    Smrekar, Suzanne E.; Stofan, Ellen R.

    1997-01-01

    Coronae are volcanotectonic features that are unique to Venus and are interpreted to be small-scale upwellings. A model in which upwelling causes delamination at the edge of the plume head, along with deformation of a pre-existing depleted mantel Layer, can produce the full range of topographic forms of coronae. If half of the coronae are active, delamination of the lower lithosphere could account for about 10% of venus's heat loss, with another 15% due to upwelling. Delamination may occur in other geologic enviroment and could help account for 'Venus' heat loss 'deficit'.

  13. The antifungal activity of corona treated polyamide and polyester fabrics loaded with silver nanoparticles

    Science.gov (United States)

    Saponjic, Z.; Ilic, V.; Vodnik, V.; Mihailovic, D.; Jovancic, P.; Nedeljkovic, J.; Radetic, M.

    2008-07-01

    This study is aimed to highlight the possibility of using the corona treatment for fiber surface activation that can facilitate the loading of silver nanoparticles from colloids onto the polyester and polyamide fabrics and thus enhance their antifungal activity against Candida albicans. Additionally, the laundering durability of achieved effects was studied. Corona activated polyamide and polyester fabrics loaded with silver nanoparticles showed better antifungal properties compared to untreated fabrics. The positive effect of corona treatment became even more prominent after 5 washing cycles, especially for polyester fabrics.

  14. Nerillidae (Annelida) from the Corona lava tube, Lanzarote, with description of Meganerilla cesari, n. sp

    DEFF Research Database (Denmark)

    Worsaae, Katrine; Martínez, A; Núñez, J

    2009-01-01

    Five species of Nerillidae are previously known from Atlantic cave systems. Another four species of Nerillidae are reported here from the Corona lava tube (Lanzarote, Canary Islands) presenting the first records of Mesonerilla and Meganerilla from anchialine environments. We here describe...... reported. Updated diagnoses are presented for Mesonerilla armoricana, reported here for the first time from the Canary Islands, and Leptonerilla diatomeophaga, the only nerillid previously known from the Corona lava tube. The Corona lava tube holds a large variety of benthic habitats, which may explain...

  15. OH radicals generated by DC corona discharge for improving the pulsed discharge desulfuration efficiency

    Institute of Scientific and Technical Information of China (English)

    LI Jie; LI Guo-feng; WU Yan; WANG Ning-hui; HUANG Qiu-nan

    2004-01-01

    Positive DC corona discharge is formed with needle-plate electrode configuration, in which the water vapor is ejected though the needle points. The purpose is to increase the numbers of the water-based radicals, ionize the water molecule and improve the desulfuration efficiency of pulsed corona reactor. The water ions were determined by four stages molecular beam mass spectrometer and diagnose the water-based radicals by emission spectrograph. A conclusion on formation of ions and radicals with DC corona discharges can be drawn.

  16. Partial Discharge Optical Pulse Signal Characteristics for Corona Defect in Oil Immersed Transformer

    Directory of Open Access Journals (Sweden)

    Jiabin Zhou

    2013-03-01

    Full Text Available Using fluorescent fiber sensor in transformer PD detection is a new method, based on the experimental platform for corona PD defect, the study has been carried out in order to show the typical corona PD defect optical pulse signal characteristics, PD single pulse waveform and pulses under industrial frequency cycle were acquired. The test results show that the optical method by using fluorescent fiber is effective in PD detection and corona PD optical pulse signals can accurately reflect the characteristics for this kind defect.

  17. The Temperature of the Corona as Derived from Total Solar Eclipse Observations

    Science.gov (United States)

    Habbal, Shadia R.; Morgan, Huw; Druckmuller, Miloslav; Ding, Adalbert

    2016-05-01

    Multiwavelength imaging observations in a suite of coronal forbidden lines of the corona during total solar eclipses enables the empirical inference of the spatial distribution of temperature in the solar corona up to a few solar radii above the limb. The temperature sensitivity of coronal emission lines is such that temperature differences of 105 K can be detected in the images. Using high resolution multiwavelength and white light eclipse images acquired since 2006, covering almost a solar cycle, we show evidence for (1) how the distribution of the temperature in the corona is bimodal, with closed coronal structures dominated by 2 106 K plasma, while structures streaming away from the Sun are dominated by 106 K emission, (2) prominences are invariably enshrouded by the hottest material in the corona, and (3) that the dominance of one temperature versus the other is solar-cycle dependent.

  18. No king without a crown--impact of the nanomaterial-protein corona on nanobiomedicine.

    Science.gov (United States)

    Docter, Dominic; Strieth, Sebastian; Westmeier, Dana; Hayden, Oliver; Gao, Mingyuan; Knauer, Shirley K; Stauber, Roland H

    2015-02-01

    Besides the wide use of nanomaterials in technical products, their application spectrum in biotechnology and biomedicine is steadily increasing. Whereas the physico-chemical properties and behavior of nanomaterials can be engineered and characterized accurately under idealized conditions, this is no longer the case in complex physiological environments. In biological fluids, proteins rapidly bind to nanomaterials forming the protein corona, critically affecting the nanomaterials' biological identity. As the corona impacts in vitro and/or in vivo nanomaterial applications, we here review the concept of the protein corona and its analytical dissection. We comment on how corona signatures may be linked to effects at the nano-bio interface and conclude how such knowledge is offering novel opportunities for improved nanomedicine.

  19. Co-existence of two plasma phases in solar and AGN coronas

    Directory of Open Access Journals (Sweden)

    Kubičela A.

    1998-01-01

    Full Text Available Here we have juxtaposed two distant cosmic locations of the Sun and AGN where neutral hydrogen appears in a close connection with hot coronas. Besides the solar photosphere, chromosphere and prominences where the presence of neutral hydrogen is well established, its emission quite high in hot solar corona is still puzzling. Some of earlier observations where Hα emission in solar corona was detected in eclipse and in daily coronagraphic observations are reviewed. A proper theoretical explanation of this cold chromospheric-type emission in the hot corona does not exist yet. On the other side, a similar emission of hydrogen lines is present in Active Galactic Nuclei (AGNs. Much research work is currently being done in this field. We outline some of the concepts of the AGN structure prevailing in the astrophysics today.

  20. Detection of Corona virus antigen by ELISA from diarrhoeic cow calves in Mathura, India

    Directory of Open Access Journals (Sweden)

    S K Dash

    2012-06-01

    Full Text Available Neonatal diarrhoea is one of the most important conditions of calves, associated with morbidity and mortalities. Diarrhoeal diseases have an adverse effect on calf health status, survival and productive performances. Corona virus is one of the etiological agents responsible for calf diarrhea worldwide. However there is paucity of literature stating the disease status in India. The present study was carried out to determine the prevalence of corona virus infection among cow calves in Mathura and adjacent regions. During the present study 63 diarrhoeic stool samples collected from cow calves were screened for corona virus. Of the 63 diarrhoeic samples 3 samples (4.76% were found to be positive for corona virus by ELISA. [Vet. World 2012; 5(3.000: 166-168

  1. Sterilisation of Hydroponic Culture Solution Contaminated by Fungi using an Atmospheric Pressure Corona Discharge

    Science.gov (United States)

    Mizukami, Kohji; Satoh, Kohki; Kanayama, Hiroshi; Itoh, Hidenori; Tagashira, Hiroaki; Shimozuma, Mitsuo; Okamoto, Hiroyuki; Takasaki, Satoko; Kinoshita, Muneshige

    The hydroponic culture solution contaminated by fungi is sterilised by a DC corona discharge, and the sterilisation characteristics are investigated in this work. A DC streamer corona discharge is generated at atmospheric pressure in air between needle clusters and a water bath containing contaminated solution by fungus such as Fusarium oxysporum f. sp. spinaciae or Fusarium sp.. It is found that the fungi are killed by the exposure of the corona discharge, and that the death rates of the fungi chiefly depend on the concentration of the hydroponic culture solutions. It is also found that the number densities of the fungi decrease exponentially with the energy expenditure of the corona discharge, and that damping coefficients of the fungi densities depend on the concentration of the hydroponic culture solutions. This suggests that the fungi are chiefly inactivated by electroporation.

  2. Numerical simulation of corona-induced vibration of high voltage conductor

    Institute of Scientific and Technical Information of China (English)

    A. GOURBI; M. BRAHAMI; A. TILMATINE; P. PIROTTE

    2009-01-01

    When it rains, electric power transmission lines start vibrating due to corona effect. This type of vibration is known as "corona-induced vibration". The aim of this paper is to elaborate a mathematical model for numerical simulation of the corona-induced vibration, with consid-eration of the influence of the magnitude and the polarity of the electric field on the conductor surface. Finite element method was employed to develop the numerical model,and the finite difference method was used for the time discretisation. The moment of application of the corona-induced force is evaluated using the resultant vertical force applied to a water drop, suspended under a high voltage conductor. Some experimental results of other authors are exploited to evaluate the precision of the simulation and the validation of numerical results.

  3. More than mass proportional heating of heavy ions by supercritical collisionless shocks in the solar corona

    CERN Document Server

    Zimbardo, Gaetano

    2009-01-01

    We propose a new model for explaining the observations of more than mass proportional heating of heavy ions in the polar solar corona. We point out that a large number of small scale intermittent shock waves can be present in the solar corona. The energization mechanism is, essentially, the ion reflection off supercritical quasi-perpendicular collisionless shocks in the corona and the subsequent acceleration by the motional electric field ${\\bf E} = - (1/c) {\\bf V} \\times {\\bf B}$. The acceleration due to ${\\bf E}$ is perpendicular to the magnetic field, in agreement with observations, and is more than mass proportional with respect to protons, because the heavy ion orbit is mostly upstream of the quasi-perpendicular shock foot. The observed temperature ratios between O$^{5+}$ ions and protons in the polar corona, and between $\\alpha$ particles and protons in the solar wind are easily recovered.

  4. Formation of Novae and Coronae on Venus. Tectonophysical Modeling Using Gravity Models

    Science.gov (United States)

    Krassilnikov, A. S.

    2001-03-01

    Novae and coronae formation was simulated using caoutchouc as a model of lower ductile part of lithosphere and dry flour as a model of upper brittle part of it. Distribution and character of the deformational structures is described.

  5. Jet magnetically accelerated from disk-corona around a rotating black hole

    Institute of Scientific and Technical Information of China (English)

    GONG XiaoLong; LI LiXin

    2012-01-01

    A jet acceleration model for extracting energy from disk-corona surrounding a rotating black hole (BH) is proposed.In the diskcorona scenario,we obtain the ratio of the power dissipated in the corona to the total for such disk-corona system by solving the disk dynamics equations.The analytical expression of the jet power is derived based on the electronic circuit theory of the magnetosphere.It is shown that jet power increases with the increasing BH spin,and concentrates in the inner region of the disk-corona.In addition,we use a sample consisting of 37 radio loud quasars to explore their jet production mechanism,and show that our jet formation mechanism can simulate almost all sources with high power jet,which fails to be explained by the Blandford-Znajek (BZ) process.

  6. The Corona Factorization Property, Stability, and the Cuntz Semigroup of a C*-algebra

    DEFF Research Database (Denmark)

    Esparza, Eduardo Ortega; Perera, F.; Rordam, M.

    2012-01-01

    The Corona Factorization Property, originally invented to study extensions of C*-algebras, conveys essential information about the intrinsic structure of the C*-algebra. We show that the Corona Factorization Property of a Sigma-unital C*-algebra is completely captured by its Cuntz semigroup (of...... equivalence classes of positive elements in the stabilization of A). The corresponding condition in the Cuntz semigroup is a very weak comparability property termed the Corona Factorization Property for semigroups. Using this result, one can, for example, show that all unital C*-algebras with a finite...... decomposition rank have the Corona Factorization Property. Applying similar techniques, we study the related question of when C*-algebras are stable. We give an intrinsic characterization, that we term property (S), of C*-algebras that have no nonzero unital quotients and no nonzero bounded 2-quasitraces. We...

  7. Plasma Using a Simulated Gas Mixture: A Case Study on the Effect of Corona Electrodes

    Institute of Scientific and Technical Information of China (English)

    K. YOSHIDA; B. S. RAJANIKANTH; M. OKUBO

    2009-01-01

    In this study, reduction and desorption of oxides of nitrogen (NOx) were conducted using an electrical discharge plasma technique. The study was carried out using a simulated gas mixture to explore the possibility of re-generation of used adsorbents by a nonthermal plasma desorption technique. Three different types of corona electrodes, namely, pipe, helical wire, and straight wire, were used for analyzing their effectiveness in NOx reduction/desorption. The pipe-type corona electrode exhibited a nitric oxide (NO) conversion of 50%, which is 1.5 times that of the straight-wire-type electrode at an energy density of 175 J/L. The helical-wire-type corona electrode exhibited a NOx desorption efficiency almost 4 times that of the pipe-type electrode, indicating the possibility that corona-generated species play a crucial role in desorption.

  8. Genetic control of orange hilum corona of carioca beans (Phaseolus vulgaris

    Directory of Open Access Journals (Sweden)

    Juarez Pires Tomaz

    2007-01-01

    Full Text Available The purpose of this research was to elucidate the genetic control of orange corona color in carioca common beans (Phaseolus vulgaris. We made four crosses between carioca group cultivars that differed in respect to the presence or absence of an orange hilum corona color. The F2, F3, F1BC11, F1BC21, F2BC11 and F2BC21 phenotypic segregations were evaluated with a chi-square test which fitted with the hypothesis that one gene with a dominant allele is responsible for the orange corona color. All generations resulting from the four different crosses showed segregation patterns which agreed with the expected proportions. Our results show that the dominant G allele controls orange corona color in the carioca bean group.

  9. A Space Weather mission concept: Observatories of the Solar Corona and Active Regions (OSCAR)

    DEFF Research Database (Denmark)

    Strugarek, Antoine; Janitzek, Nils; Lee, Arrow

    2015-01-01

    Coronal Mass Ejections (CMEs) and Corotating Interaction Regions (CIRs) are major sources of magnetic storms on Earth and are therefore considered to be the most dangerous space weather events. The Observatories of Solar Corona and Active Regions (OSCAR) mission is designed to identify the 3D str....... The spacecraft will be separated by an angle of 68 degrees to provide optimum stereoscopic view of the solar corona. We study the feasibility of such a mission and propose a preliminary design for OSCAR....

  10. Hi-C Observations of an Active Region Corona, and Investigation of the Underlying Magnetic Structure

    Science.gov (United States)

    Tiwari, S. K.; Alexander, C. E.; Winebarger, A.; Moore, R. L.

    2014-01-01

    The solar corona is much hotter (>=10(exp 6) K) than its surface (approx 6000 K), puzzling astrophysicists for several decades. Active region (AR) corona is again hotter than the quiet Sun (QS) corona by a factor of 4-10. The most widely accepted mechanism that could heat the active region corona is the energy release by current dissipation via reconnection of braided magnetic field structure, first proposed by E. N. Parker three decades ago. The first observational evidence for this mechanism has only recently been presented by Cirtain et al. by using High-resolution Coronal Imager (Hi-C) observations of an AR corona at a spatial resolution of 0.2 arcsec, which is required to resolve the coronal loops, and was not available before the rocket flight of Hi-C in July 2012. The Hi-C project is led by NASA/MSFC. In the case of the QS, work done by convection/granulation on the inter-granular feet of the coronal field lines translates into the heat observed in the corona. In the case of the AR, as here, there could be flux emergence, cancellation/submergence, or shear flows generating large stress and tension in coronal field loops which is released as heat in the corona. We are currently investigating the changes taking place in photospheric feet of the magnetic field involved with brightenings in the Hi-C AR corona. For this purpose, we are also using SDO/AIA data of +/- 2 hours around the 5 minutes Hi-C flight. In the present talk, I will first summarize some of the results of the Hi-C observations and then present some results from our recent analysis on what photospheric processes feed the magnetic energy that dissipates into heat in coronal loops.

  11. Experimental study on the onset of positive corona in atmospheric air

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, George C; Bregnsbo, E.

    1979-01-01

    This paper reports the findings of a study into the gas physical processes which lead to the inception of the positive corona discharge in atmospheric air. A multiple avalanche process is observed to be a basic feature, and correlation with the works reported in the literature suggests...... that at corona onset the physical phenomena are independent of electrode radius of curvature rho in the range 0.04...

  12. Shock Formation Height in the Solar Corona Estimated from SDO and Radio Observations

    Science.gov (United States)

    Gopalswamy, N.; Nitta, N.

    2011-01-01

    Wave transients at EUV wavelengths and type II radio bursts are good indicators of shock formation in the solar corona. We use recent EUV wave observations from SDO and combine them with metric type II radio data to estimate the height in the corona where the shocks form. We compare the results with those obtained from other methods. We also estimate the shock formation heights independently using white-light observations of coronal mass ejections that ultimately drive the shocks.

  13. Observations of the temperature, density and velocity structure of the solar corona

    Science.gov (United States)

    Osterman, Steven Neil

    1994-01-01

    The solar corona exists at a temperature of over 106 K while the underlying visible surface, the photosphere, is much cooler, about 6,000K. How this tenuous outer layer can be many orders of magnitude hotter than the photosphere is one of the principal enigmas of solar physics. Various mechanisms have been proposed to explain coronal heating, but none have been completely successful in accounting for its observed characteristics. It is the purpose of this thesis to present observations of both the large scale velocity structure and the small scale density and temperature structure of the quiet corona which will constrain theories of coronal heating. Spatially resolved spectra of the solar corona were obtained in the extreme ultraviolet during a sounding rocket experiment on June 20, 1989. In order to obtain an accurate photometric calibration of the spectrometer, we developed a new technique using a synchrotron radiation source operated by the National Institute for Standards and Technology. With this calibration, along with the high spectral resolution and on-board wavelength calibration capability of the payload, we were able to develop a detailed picture of the density and velocity structure of a portion of the solar corona. Data from the sounding rocket experiment were then compared to white light observations made by the Mk-3 coronagraph operated by the High Altitude Observatory at Mauna Loa. The white light continuum intensity of the solar corona is proportional to the mean electron density along the line of sight, whereas the emission line intensity is proportional to the average value of the electron density squared. By comparing these two data sets, we find that the density irregularity factor is close to unity for the quiet corona. The irregularity analysis in this thesis is the first to consider the possibility of a non-isothermal corona. We also find that the systematic velocity structure seen in the transition region is not present in the solar corona.

  14. Absolute Free Energy of Binding and Entropy of the FKBP12-FK506 Complex: Effects of the Force Field.

    Science.gov (United States)

    General, Ignacio J; Meirovitch, Hagai

    2013-10-08

    The hypothetical scanning molecular dynamics (HSMD) method combined with thermodynamic integration (HSMD-TI) has been extended recently for calculating ΔA(0)-the absolute free energy of binding of a ligand to a protein. With HSMD-TI, ΔA(0) is obtained in a new way as a sum of several components, among them is ΔSligand-the change in the conformational entropy as the ligand is transferred from the bulk solvent to the active site-this entropy is obtained by a specific reconstruction procedure. This unique aspect of HSMD (which is useful in rational drug design) is in particular important for treating large ligands, where ΔSligand might be significant. Technically, one should verify that the results for ΔSligand converge-a property that might become more difficult for large ligands; therefore, studying ligands of increasing size would define the range of applicability of HSMD-TI for binding. In this paper, we check the performance of HSMD-TI by applying it to the relatively large ligand FK506 (126 atoms) complexed with the protein FKBP12, where ΔA(0) = -12.8 kcal/mol is known experimentally as well as the crystal structure of the complex. This structure was initially equilibrated by carrying out a 100 ns molecular dynamics trajectory, where the system is modeled by the AMBER force field, TIP3P water, and Particle Mesh Ewald. HSMD-TI calculations were carried out in three conformational regions defined by the intervals [0.2,2], [2,5], and [5,100] ns along the trajectory, where local equilibration of the total energy has been observed; we obtained ΔA(0) = -13.6 ± 1.1, -16.6 ± 1.4, and -16.7 ± 1.4 kcal/mol, respectively indicating the following: (1) The second and third regions belong to the same conformational subspace of the complex, which is different from the [0.2,2] ns subspace. (2) The unsatisfactory result for ΔA(0) obtained in the well equilibrated (hence theoretically preferred) latter regions reflects the nonperfect modeling used, which however (3

  15. Characterisation of corona-generated ions used in a Neutral cluster and Air Ion Spectrometer (NAIS

    Directory of Open Access Journals (Sweden)

    H. E. Manninen

    2011-04-01

    Full Text Available We characterized size and chemical composition of ions generated by a corona-needle charger of a Neutral cluster and Air Ion Spectrometer (NAIS by using a high resolution differential mobility analyzer and a time-of-flight mass spectrometer. Our study is crucial to verify the role of corona-generated ions in the particle size spectra measured with the NAIS, in which a corona charger is used to charge aerosol particles down to the size range overlapping with the size of generated ions. The size and concentration of ions produced by the corona discharging process depend both on corona voltage and on properties and composition of carrier gas. Negative ions were <1.6 nm (0.8 cm2 V−1 s−1 in mobility in all tested gas mixtures (nitrogen, air with variable mixing ratios of water vapour, whereas positive ions were <1.7 nm (0.7 cm2 V−1 s−1. Electrical filtering of the corona-generated ions and not removing all charged particles plays an important role in determining the lowest detection limit. Based on our experiments, the lowest detection limit for the NAIS in the particle mode is between 2 and 3 nm.

  16. Characterisation of corona-generated ions used in a Neutral cluster and Air Ion Spectrometer (NAIS

    Directory of Open Access Journals (Sweden)

    H. E. Manninen

    2011-12-01

    Full Text Available We characterized size and chemical composition of ions generated by a corona-needle charger of a Neutral cluster and Air Ion Spectrometer (NAIS by using a high resolution differential mobility analyzer and a time-of-flight mass spectrometer. Our study is crucial to verify the role of corona-generated ions in the particle size spectra measured with the NAIS, in which a corona charger is used to charge aerosol particles down to the size range overlapping with the size of generated ions. The size and concentration of ions produced by the corona discharging process depend both on corona voltage and on properties and composition of carrier gas. Negative ions were <1.6 nm (0.8 cm2 V−1 s−1 in mobility in all tested gas mixtures (nitrogen, air with variable mixing ratios of water vapour, whereas positive ions were <1.7 nm (0.7 cm2 V−1 s−1. Electrical filtering of the corona generated ions and not removing all charged particles plays an important role in determining the lowest detection limit. Based on our experiments, the lowest detection limit for the NAIS in the particle mode is between 2 and 3 nm.

  17. Minimizing Corona on Power Distribution Lines Using Optimization by Graphical Method

    Directory of Open Access Journals (Sweden)

    Osita Oputa

    2015-11-01

    Full Text Available Each time Corona phenomenon occur in a transmission or distribution line, it result a high power loss, hence reducing transmission efficiency and profitability in electricity business. It may be practically impossible to eradicate these corona losses, however, efforts must be made towards minimizing its occurrences. Research has proven that increasing the spacing of the three phase in power transmission lines reduce the effect of corona. However, increasing the phase spacing increases the line inductance and hence the reactive power loss along the line which may cause low voltage (or voltage instability at load centers. This paper will find the exact spacing between conductors of the three phases at which the corona losses will be minimal and at the same time the reactive power lost due to the inductance caused by the spacing will not exceed recognized standard. A cable/conductor sizes of 150mm2 will be analyzed will be used in the analysis; on using a 150mm2 size of cable for transmitting 7.5MVA, a conductor spacing of 87cm was found to be the best with corona loss of 2.80kVA/km and a corresponding reactive power loss of 5.28kVA/km. Further increase in conductor spacing will although reduce corona lost, the corresponding reactive power lost will be beyond the acceptable limit

  18. Swords into Ploughshares: Archaeological Applications of CORONA Satellite Imagery in the Near East

    Directory of Open Access Journals (Sweden)

    Jesse Casana

    2012-09-01

    Full Text Available Since their declassification in 1995, CORONA satellite images collected by the United States military from 1960-1972 have proved to be an invaluable resource in the archaeology of the Near East. Because CORONA images pre-date the widespread construction of reservoirs, urban expansion, and agricultural intensification the region has undergone in recent decades, these high-resolution, stereo images preserve a picture of archaeological sites and landscapes that have often been destroyed or obscured by modern development. Despite its widely recognised value, the application of CORONA imagery in archaeological research has remained limited to a small group of specialists, largely because of the challenges involved in correcting spatial distortions produced by the satellites' unusual panoramic cameras. This article presents results of an effort to develop new methods of efficiently orthorectifying CORONA imagery and to use these methods to produce geographically corrected images across the Near East, now freely available through an online database. Following an overview of our methods, we present examples of how recent development has affected the archaeological record, new discoveries that analysis of our CORONA imagery database has already made possible, and emerging applications of CORONA including stereo analysis and DEM extraction.

  19. The existence of warm and optically thick dissipative coronae above accretion disks

    CERN Document Server

    Rozanska, A; Belmont, R; Czerny, B; Petrucci, P -O

    2015-01-01

    In the past years, several observations of AGN and X-ray binaries have suggested the existence of a warm T around 0.5-1 keV and optically thick, \\tau ~ 10-20, corona covering the inner parts of the accretion disk. These properties are directly derived from spectral fitting in UV to soft-X-rays using Comptonization models. However, whether such a medium can be both in radiative and hydrostatic equilibrium with an accretion disk is still uncertain. We investigate the properties of such warm, optically thick coronae and put constraints on their existence. We solve the radiative transfer equation for grey atmosphere analytically in a pure scattering medium, including local dissipation as an additional heating term in the warm corona. The temperature profile of the warm corona is calculated assuming it is cooled by Compton scattering, with the underlying dissipative disk providing photons to the corona. Our analytic calculations show that a dissipative thick, (\\tau_{cor} ~ 10-12) corona on the top of a standard ac...

  20. Diagnostics of the solar corona from comparison between Faraday rotation measurements and magnetohydrodynamic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Le Chat, G.; Cohen, O. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Kasper, J. C. [Atmospheric, Oceanic and Space Sciences Department, University of Michigan, Ann Arbor, MI (United States); Spangler, S. R., E-mail: gaetan.lechat@obspm.fr [Department of Physics and Astronomy, University of Iowa, Iowa City, IA (United States)

    2014-07-10

    Polarized natural radio sources passing behind the Sun experience Faraday rotation as a consequence of the electron density and magnetic field strength in coronal plasma. Since Faraday rotation is proportional to the product of the density and the component of the magnetic field along the line of sight of the observer, a model is required to interpret the observations and infer coronal structures. Faraday rotation observations have been compared with relatively ad hoc models of the corona. Here for the first time we compare these observations with magnetohydrodynamic (MHD) models of the solar corona driven by measurements of the photospheric magnetic field. We use observations made with the NRAO Very Large Array of 34 polarized radio sources occulted by the solar corona between 5 and 14 solar radii. The measurements were made during 1997 May, and 2005 March and April. We compare the observed Faraday rotation values with values extracted from MHD steady-state simulations of the solar corona. We find that (1) using a synoptic map of the solar magnetic field just one Carrington rotation off produces poorer agreements, meaning that the outer corona changes in the course of one month, even in solar minimum; (2) global MHD models of the solar corona driven by photospheric magnetic field measurements are generally able to reproduce Faraday rotation observations; and (3) some sources show significant disagreement between the model and the observations, which appears to be a function of the proximity of the line of sight to the large-scale heliospheric current sheet.

  1. Analysis and Identification of Corona Parameters on Overhead Power Lines in Case of Direct Lightning Strikes

    Institute of Scientific and Technical Information of China (English)

    Bajorek J; Maslowski G; Ziemba R

    2013-01-01

    This paper presents a method for determining specific models of overhead power lines with presence of corona phenomenon.The obtained models provide stable numerical solutions for computer simulation of transients caused by direct lightning strikes.The corona nonlinear charge-voltage characteristics obtained from experimental tests are used for identification of the corona parameters based on System Identification Toolbox implemented in Matlab package.Different transfer functions,which give the same waveshapes of overvoltages are determined using two parametric models.A circuit representation of the obtained transfer functions is proposed and the corona model is implemented in the EMTP-RV as a hierarchical structure composed of a overhead power line divided into sections with corona branches.Some computer simulations of lightning overvoltages propagated in a typical 220 kV power line due to direct lightning strikes to a line tower are presented.The proposed method and the model implemented in EMTP-RV are still valid for multi-conductor lines and for higher voltages of power lines but new corona nonlinear charge-voltage characteristics are required as an input parameter for the identification procedure.

  2. Core-corona PSt/P(BA-AA) composite particles by two-stage emulsion polymerization

    Science.gov (United States)

    Xie, Delong; Ren, Xiaolin; Zhang, Xinya; Liao, Shijun

    2016-03-01

    Raspberry-shaped composite particles with polystyrene (PSt) as core and poly(n-butyl acrylate-co-acrylic acid) (P(BA-AA)) as corona were synthesized via emulsion polymerization. The random copolymer, P(BA-AA), was pre-prepared and used as a polymeric surfactant, its emulsifying properties adjusted by changing the mass ratio of BA and AA. The morphology of the resulting core-corona composite particles, P(St/P(BA-AA)), could be regulated and controlled by varying the concentrations of P(BA-AA) or the mass ratio of BA:AA in P(BA-AA). The experimental results indicate that 3.0-6.0 wt% of P(BA-AA) is required to obtain stable composite emulsions, and P(BA-AA) with a mass ratio of BA:AA = 1:2 is able to generate distinct core-corona structures. A mechanism of composite particle formation is proposed based on the high affinity between the PSt core and the hydrophobic segments of P(BA-A). The regular morphology of the colloidal film is expected to facilitate potential application of core-corona particles in the field of light scattering. Furthermore, the diversity of core-corona particles can be expanded by replacing P(BA-AA) corona particles with other amphiphilic particles.

  3. Corona noise model of high-voltage AC transmission lines and engineering applications

    Institute of Scientific and Technical Information of China (English)

    Wu Jiuhui; Di Zelong

    2013-01-01

    In order to predict the levels of corona noise from high-voltage alternating current (AC) transmission lines,the mechanism of corona noise and the corresponding theoretical prediction model are investigated.On the basis of Drude model,the motion of positive and negative ions produced by high-voltage corona is analyzed,and the mechanism of corona noise is discovered.The theoretical prediction model is put forward by using Kirchhoff formula,which is verified by the well agreement between our result and others',considering the case of three-phase single lines.Moreover,the calculation results show that for both single and bundled lines,the sound pressure level of the typical frequency,i.e.twice the power frequency,attenuates slowly and leads to an obviously interferential phenomenon near the transmission lines,but the level of the bundled lines is smaller than that of the single ones under the same transmission voltage.Based on the mechanism of corona noise and the prediction model,it is obvious that bundled lines and/or increased line radius can be adopted to reduce corona noise in the practical engineering applications effectively.This model can also provide a theoretical guidance for the high-volt-age AC transmission line design.

  4. Modification of the protein corona-nanoparticle complex by physiological factors.

    Science.gov (United States)

    Braun, Nicholas J; DeBrosse, Madeleine C; Hussain, Saber M; Comfort, Kristen K

    2016-07-01

    Nanoparticle (NP) effects in a biological system are driven through the formation and structure of the protein corona-NP complex, which is dynamic by nature and dependent upon factors from both the local environment and NP physicochemical parameters. To date, considerable data has been gathered regarding the structure and behavior of the protein corona in blood, plasma, and traditional cell culture medium. However, there exists a knowledge gap pertaining to the protein corona in additional biological fluids and following incubation in a dynamic environment. Using 13nm gold NPs (AuNPs), functionalized with either polyethylene glycol or tannic acid, we demonstrated that both particle characteristics and the associated protein corona were altered when exposed to artificial physiological fluids and under dynamic flow. Furthermore, the magnitude of observed behavioral shifts were dependent upon AuNP surface chemistry. Lastly, we revealed that exposure to interstitial fluid produced protein corona modifications, reshaping of the nano-cellular interface, modified AuNP dosimetry, and induction of previously unseen cytotoxicity. This study highlights the need to elucidate both NP and protein corona behavior in biologically representative environments in an effort to increase accurate interpretation of data and transfer of this knowledge to efficacy, behavior, and safety of nano-based applications.

  5. The effect of protein corona composition on the interaction of carbon nanotubes with human blood platelets.

    Science.gov (United States)

    De Paoli, Silvia H; Diduch, Lukas L; Tegegn, Tseday Z; Orecna, Martina; Strader, Michael B; Karnaukhova, Elena; Bonevich, John E; Holada, Karel; Simak, Jan

    2014-08-01

    Carbon nanotubes (CNT) are one of the most promising nanomaterials for use in medicine. The blood biocompatibility of CNT is a critical safety issue. In the bloodstream, proteins bind to CNT through non-covalent interactions to form a protein corona, thereby largely defining the biological properties of the CNT. Here, we characterize the interactions of carboxylated-multiwalled carbon nanotubes (CNTCOOH) with common human proteins and investigate the effect of the different protein coronas on the interaction of CNTCOOH with human blood platelets (PLT). Molecular modeling and different photophysical techniques were employed to characterize the binding of albumin (HSA), fibrinogen (FBG), γ-globulins (IgG) and histone H1 (H1) on CNTCOOH. We found that the identity of protein forming the corona greatly affects the outcome of CNTCOOH's interaction with blood PLT. Bare CNTCOOH-induced PLT aggregation and the release of platelet membrane microparticles (PMP). HSA corona attenuated the PLT aggregating activity of CNTCOOH, while FBG caused the agglomeration of CNTCOOH nanomaterial, thereby diminishing the effect of CNTCOOH on PLT. In contrast, the IgG corona caused PLT fragmentation, and the H1 corona induced a strong PLT aggregation, thus potentiating the release of PMP.

  6. Controlling the Properties of Solvent-free Fe3O4 Nanofluids by Corona Structure

    Institute of Scientific and Technical Information of China (English)

    Yumo Tan; Yaping Zheng∗; Nan Wang; Aibo Zhang

    2012-01-01

    We studied the relationship between corona structure and properties of solvent-free Fe3O4 nanoflu-ids. We proposed a series of corona structures with different branched chains and synthesize different solvent-free nanofluids in order to show the effect of corona structure on the phase behavior, dispersion, as well as rheol-ogy properties. Results demonstrate novel liquid-like behaviors without solvent at room temperature. Fe3O4 magnetic nanoparticles content is bigger than 8%and its size is about 2∼3 nm. For the solvent-free nanofluids, the long chain corona has the internal plasticization, which can decrease the loss modulus of system, while the short chain of corona results in the high viscosity of nanofluids. Long alkyl chains of modifiers lead to lower viscosity and better flowability of nanofluids. The rheology and viscosity of the nanofluids are correlated to the microscopic structure of the corona, which provide an in-depth insight into the preparing nanofluids with promising applications based on their tunable and controllable physical properties.

  7. Protein Corona Influences Cell-Biomaterial Interactions in Nanostructured Tissue Engineering Scaffolds.

    Science.gov (United States)

    Serpooshan, Vahid; Mahmoudi, Morteza; Zhao, Mingming; Wei, Ke; Sivanesan, Senthilkumar; Motamedchaboki, Khatereh; Malkovskiy, Andrey V; Gladstone, Andrew B; Cohen, Jeffrey E; Yang, Phillip C; Rajadas, Jayakumar; Bernstein, Daniel; Woo, Y Joseph; Ruiz-Lozano, Pilar

    2015-07-22

    Biomaterials are extensively used to restore damaged tissues, in the forms of implants (e.g. tissue engineered scaffolds) or biomedical devices (e.g. pacemakers). Once in contact with the physiological environment, nanostructured biomaterials undergo modifications as a result of endogenous proteins binding to their surface. The formation of this macromolecular coating complex, known as 'protein corona', onto the surface of nanoparticles and its effect on cell-particle interactions are currently under intense investigation. In striking contrast, protein corona constructs within nanostructured porous tissue engineering scaffolds remain poorly characterized. As organismal systems are highly dynamic, it is conceivable that the formation of distinct protein corona on implanted scaffolds might itself modulate cell-extracellular matrix interactions. Here, we report that corona complexes formed onto the fibrils of engineered collagen scaffolds display specific, distinct, and reproducible compositions that are a signature of the tissue microenvironment as well as being indicative of the subject's health condition. Protein corona formed on collagen matrices modulated cellular secretome in a context-specific manner ex-vivo, demonstrating their role in regulating scaffold-cellular interactions. Together, these findings underscore the importance of custom-designing personalized nanostructured biomaterials, according to the biological milieu and disease state. We propose the use of protein corona as in situ biosensor of temporal and local biomarkers.

  8. Solar Corona and plasma effects on Radio Frequency waves

    Science.gov (United States)

    Nkono, C.; Rosenblatt, P.; Dehant, V. M.

    2009-12-01

    Solar corona (plasma) effects on radio signal waves for three different frequency bands S (2.3 GHz), X (8.4 GHz), and Ka (32 GHz), currently used to track probes in the solar system, have been computed using different models of the total electron content (TEC) along the propagation path between the Earth and Mars. The Earth-Mars-Sun configuration has been obtained from the planetary ephemerides DE421 (using SPICE kernels) for the period from September 2004 to September 2006. This configuration is expressed as a function of the Sun-Earth-Probe (SEP) angles (the probe being in close orbit to Mars). We used the TEC values provided by the different models proposed in the literature in order to estimate the TEC along the propagation path (STEC, for Slant TEC). From these model-dependent STEC estimates, the time delay on the wave propagation as well as the associated frequency shift with a 10 seconds sampling time have been obtained for each of the three frequency bands. For the X-band mostly used in radio science, we have obtained estimates differing by up to several orders of magnitude due to the different STEC values derived from different models of TEC. For example, if the propagation path passes near the Sun such that SEP angle is 1.55° the STEC is ranging from 4.6x1020 electron/m2 to 6.07x1016 electron/m2, which corresponds to a time delay range between 0.87 μs and 1.15x10-4 μs, respectively. For SEP angles between 2° and 8°, the range of the different time delay values reduces to 2.8x10-1 μs and becomes as small as 1.6x10-2 μs for SEP angles larger than 8° (1x10-2 μs is about the order of magnitude of the radioscience instrument precision). These results show that the correction of the solar corona effect on radio frequency waves can be reliably done on usual X-band tracking data of spacecraft for SEP angles >12°, but should be use with caution for lower SEP angles, especially lower than 2°.

  9. Influência do imunossupressor tacrolimus (FK-506 na resistência à flexão de fêmures: estudo em ratos Influence of the immunosuppressant tacrolimus (FK-506 on the flexural strength of femur: a study in rats

    Directory of Open Access Journals (Sweden)

    Matheus Melo Pithon

    2010-06-01

    Full Text Available OBJETIVO: Avaliar a resistência à fratura de fêmures de ratos tratados com o imunossupressor tacrolimus FK-506 e compará-los a ratos tratados com placebo e não tratados. MÉTODOS: Foram utilizados 90 ratos da linhagem Wistar machos. Os animais tinham nove semanas de idade e peso entre 220 e 280g. O medicamento utilizado neste estudo foi o agente imunossupressor tacrolimus administrado por via oral, 2mg/kg/dia. A suspensão foi administrada com auxílio de seringa de insulina, sendo a dose terapêutica de manutenção suficiente para manter a atividade imunossupressora. Os animais foram divididos aleatoriamente em três grupos (n = 30: grupo 1, nenhuma substância administrada; grupo 2, administração do imunossupressor tacrolimus FK-506; e grupo 3, administrado apenas veículo. O tratamento com FK-506 foi realizado por 28 dias. Foram avaliadas as contagens totais de leucócitos e diferencial (linfócitos, monócitos, eosinófilos e neutrófilos, com objetivo de monitoramento do efeito imunossupressor. Uma outra análise realizada foi a da densitometria óssea por absorção de raios-X de dupla energia (DXA antes e após administração do fármaco. Para avaliar a resistência à flexão, desenvolveu-se dispositivo que serviu de apoio para realização dos ensaios mecânicos em máquina universal de ensaios mecânicos EMIC. RESULTADOS: Os resultados da resistência à flexão demonstraram diferenças estatísticas entre os grupo 1 e 2 (p = 0,001 e 2 e 3 (p = 0,001. Não foram encontradas diferenças estatísticas entre os grupos 1 e 3 (p = 0,995. CONCLUSÕES: Os fêmures de ratos tratados com o imunossupressor apresentam menor resistência mecânica que os de ratos normais e os que utilizaram placebo.OBJECTIVE: To evaluate the resistance to femur fractures in rats treated with the immunosuppressant tacrolimus FK-506 and compare them to untreated rats and rats treated with placebo. METHODS: We used 90 male Wistar rats. The animals were 9

  10. The effect of FK506 on kinetic activity of IFN-γ, IL-2 and parasite load in liver in mice with Toxoplasmosis%FK506对弓形虫感染后小鼠IFN-γ、IL-2和肝虫负荷的影响

    Institute of Scientific and Technical Information of China (English)

    郑顺利; 杨庆生; 马小红

    2006-01-01

    目的 探讨免疫抑制剂FK506(他克莫司,Tacrolimus)对弓形虫急性感染后小鼠干扰素γ(IFN-γ)和白介素2(IL-2)的活性以及对肝虫负荷的影响.方法 用102个RH株弓形虫速殖子腹腔接种昆明小鼠120只,然后随机分为FK506组[A组,每d用FK506 1mg/(kg·d)灌胃]和对照组(B组,每d用等量生理盐水灌胃),每组60只,雌雄各半;分别于感染后第2、4、6、7、9 d随机取8只小鼠外周血,用ELISA法测定血清IFN-γ和IL-2的活性,同时取肝脏用荧光定量PCR法检测肝脏的虫荷.另外检测8只健康小鼠的IFN-γ和IL-2数值,作为正常值.结果 A组小鼠于感染后第8d全部死亡,B组小鼠于感染后第10d全部死亡.感染后第2、4、6、7 d A组小鼠血清IFN-γ活性明显低于B组(P<0.05或P<0.01).IL-2活性除感染后第2d两组在统计学上无显著性差异外,从感染后第4 d开始,A组的IL-2水平显著低于B组,而且差别越来越显著(P<0.05或P<0.01).在感染后第4和第7 d A组的肝平均虫荷显著高于B组(P<0.01).结论 FK506对T淋巴细胞免疫有显著的抑制作用,导致机体的免疫力下降,加剧弓形虫的感染.

  11. Neutral Hydrogen and its Emission Lines in the Solar Corona

    CERN Document Server

    Vial, Jean-Claude

    2016-01-01

    Since the Lalpha rocket observations of (Gabriel, Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisionnal and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun cente...

  12. Molecular exchange in block copolymer micelles: when corona chains overlap

    Science.gov (United States)

    Lu, Jie; Lodge, Timothy; Bates, Frank; Choi, Soohyung

    2013-03-01

    The chain exchange kinetics of poly(styrene-b-ethylenepropylene) (PS-PEP) diblock copolymer micelles in squalane (C30H62) was investigated using time-resolved small angle neutron scattering (TR-SANS). The solvent is a mixture of h-squalane and d-squalane that contrast-matches a mixed 50/50 h/d PS micelle core. As isotope labeled chains exchange, the core contrast decreases, leading to a reduction in scattering intensity. This strategy therefore allows direct probing of the chain exchange rate. Separate copolymer micellar solutions containing either deuterium labeled (dPS) or normal (hPS) poly(styrene) core blocks were prepared and mixed at room temperature, below the core glass transition temperature. The samples were heated to several temperatures (around 100 °C) and monitored by TR-SANS every 5 min. As polymer concentration was increased from 1% to 15% by volume, we observed a significant slowing down of chain exchange rate. Similar retarded kinetics was found when part of the solvent in the 1% solution was replaced by homopolymer PEP (comparable size as corona block). Furthermore, if all the solvent is replaced with PEP, no exchange was detected for up to 3hr at 200 °C. These results will be discussed in terms of a molecular model for chain exchange Infineum, Iprime, NIST, ORNL

  13. Catalytic oxidation of benzene using DBD corona discharges.

    Science.gov (United States)

    Lu, B; Zhang, X; Yu, X; Feng, T; Yao, S

    2006-09-01

    Plasma oxidation of benzene (C(6)H(6)) in oxygen and nitrogen was investigated using a dielectric barrier discharge (DBD) reactor with or without MnO2 or TiO2 at atmospheric pressure and without external heating except plasma heating. An alternative current power supply was used to generate corona discharges for the plasma oxidation. The energy density was controlled under 200 J/L to keep an increase in gas temperature less than 167 K. C(6)H(6) was oxidized to carbon monoxide (CO) and dioxide (CO(2)). Typically, the energy efficiency at an energy density of 92J/L was about 0.052, 0.039, and 0.024 mol/kWh with MnO2, TiO2, and without MnO2 and TiO2, respectively. Benzene oxidation mechanism was mentioned. A comparison on energy efficiency as a function of initial concentration of hydrocarbons, inorganic sulphur compounds, and chloro (fluoro and bromo) carbons was given.

  14. Food waste management using an electrostatic separator with corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Koonchun; Teh, Pehchiong [Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman (Malaysia); Lim, Sooking [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman (Malaysia)

    2015-05-15

    In Malaysia, municipal solid waste contains a high portion of organic matters, typically contributed by food waste. It is estimated that about 45% of the municipal waste are food waste, followed by the non-food waste such as plastics, metals, glass and others. Food waste, while being properly sorted and contamination free from non-food waste, can be reused (e.g. fertiliser) instead of being landfilled. Therefore, recycling of food waste is crucial not only from the view point of waste management, but also with respect to the reduction of resource losses and greenhouse gases emission. A new waste separation process involved food particles, non-food particles and electrostatic discharge was investigated in this study. The empirical results reveal that the corona electrostatic separation is an environmental-friendly way in recovering foods from municipal waste. The efficiency of the separator, under same operating conditions, varies with the particle size of the food and non-food particles. The highest efficiency of 82% is recorded for the particle sizes between 1.5 and 3.0 mm.

  15. Food waste management using an electrostatic separator with corona discharge

    Science.gov (United States)

    Lai, Koonchun; Lim, Sooking; Teh, Pehchiong

    2015-05-01

    In Malaysia, municipal solid waste contains a high portion of organic matters, typically contributed by food waste. It is estimated that about 45% of the municipal waste are food waste, followed by the non-food waste such as plastics, metals, glass and others. Food waste, while being properly sorted and contamination free from non-food waste, can be reused (e.g. fertiliser) instead of being landfilled. Therefore, recycling of food waste is crucial not only from the view point of waste management, but also with respect to the reduction of resource losses and greenhouse gases emission. A new waste separation process involved food particles, non-food particles and electrostatic discharge was investigated in this study. The empirical results reveal that the corona electrostatic separation is an environmental-friendly way in recovering foods from municipal waste. The efficiency of the separator, under same operating conditions, varies with the particle size of the food and non-food particles. The highest efficiency of 82% is recorded for the particle sizes between 1.5 and 3.0 mm.

  16. What is the Shell Around R Coronae Borealis?

    CERN Document Server

    Montiel, Edward J; Marcello, Dominic C; Lockman, Felix J

    2015-01-01

    The hydrogen-deficient, carbon-rich R Coronae Borealis (RCB) stars are known for being prolific producers of dust which causes their large iconic declines in brightness. Several RCB stars, including R CrB, itself, have large extended dust shells seen in the far-infrared. The origin of these shells is uncertain but they may give us clues to the evolution of the RCB stars. The shells could form in three possible ways. 1) they are fossil Planetary Nebula (PN) shells, which would exist if RCB stars are the result of a final, helium-shell flash, 2) they are material left over from a white-dwarf merger event which formed the RCB stars, or 3) they are material lost from the star during the RCB phase. Arecibo 21-cm observations establish an upper limit on the column density of H I in the R CrB shell implying a maximum shell mass of $\\lesssim$0.3 M$_{\\odot}$. A low-mass fossil PN shell is still a possible source of the shell although it may not contain enough dust. The mass of gas lost during a white-dwarf merger even...

  17. Energy Input Flux in the Global Quiet-Sun Corona

    Science.gov (United States)

    Mac Cormack, Cecilia; Vásquez, Alberto M.; López Fuentes, Marcelo; Nuevo, Federico A.; Landi, Enrico; Frazin, Richard A.

    2017-07-01

    We present first results of a novel technique that provides, for the first time, constraints on the energy input flux at the coronal base (r ˜ 1.025 R ⊙) of the quiet Sun at a global scale. By combining differential emission measure tomography of EUV images, with global models of the coronal magnetic field, we estimate the energy input flux at the coronal base that is required to maintain thermodynamically stable structures. The technique is described in detail and first applied to data provided by the Extreme Ultraviolet Imager instrument, on board the Solar TErrestrial RElations Observatory mission, and the Atmospheric Imaging Assembly instrument, on board the Solar Dynamics Observatory mission, for two solar rotations with different levels of activity. Our analysis indicates that the typical energy input flux at the coronal base of magnetic loops in the quiet Sun is in the range ˜0.5-2.0 × 105 (erg s-1 cm-2), depending on the structure size and level of activity. A large fraction of this energy input, or even its totality, could be accounted for by Alfvén waves, as shown by recent independent observational estimates derived from determinations of the non-thermal broadening of spectral lines in the coronal base of quiet-Sun regions. This new tomography product will be useful for the validation of coronal heating models in magnetohydrodinamic simulations of the global corona.

  18. Towards metals analysis using corona discharge ionization ion mobility spectrometry.

    Science.gov (United States)

    Jafari, Mohammad T; Saraji, Mohammad; Sherafatmand, Hossein

    2016-02-25

    For the first time, the capability of corona discharge ionization ion mobility spectrometry (CD-IMS) in the determination of metal complex was evaluated. The extreme simplicity of dispersive liquid-liquid microextraction (DLLME) coupled to the high sensitivity of CD-IMS measurement could make this combination really useful for simple, rapid, and sensitive determination of metals in different samples. In this regard, mercury, as a model metal, was complexed with diethyldithiocarbamate (DEDTC), and then extracted into the carbon tetrachloride using DLLME. Some parameters affecting the extraction efficiency, including the type and volume of the extraction solvent, the type and volume of the disperser solvent, the concentration of the chelating agent, salt addition and, pH were exhaustively investigated. Under the optimized condition, the enrichment factor was obtained to be 142. The linear range of 0.035-10.0 μg mL(-1) with r(2) = 0.997 and the detection limit of 0.010 μg mL(-1) were obtained. The relative standard deviation values were calculated to be lower than 4% and 8% for intra-day and inter-day, respectively. Finally, the developed method was successfully applied for the extraction and determination of mercury in various real samples. The satisfactory results revealed the capability of the proposed method in trace analysis without tedious derivatization or hydride generation.

  19. Magnetic jam in the corona of the Sun

    Science.gov (United States)

    Chen, F.; Peter, H.; Bingert, S.; Cheung, M. C. M.

    2015-06-01

    The outer solar atmosphere, the corona, contains plasma at temperatures of more than a million kelvin--more than 100 times hotter than the solar surface. How this gas is heated is a fundamental question tightly interwoven with the structure of the magnetic field. Together this governs the evolution of coronal loops, the basic building block prominently seen in X-rays and extreme ultraviolet (EUV) images. Here we present numerical experiments accounting for both the evolving three-dimensional structure of the magnetic field and its complex interaction with the plasma. Although the magnetic field continuously expands as new magnetic flux emerges through the solar surface, plasma on successive field lines is heated in succession, giving the illusion that an EUV loop remains roughly at the same place. For each snapshot the EUV images outline the magnetic field. However, in contrast to the traditional view, the temporal evolution of the magnetic field and the EUV loops can be quite different. This indicates that the thermal and the magnetic evolution in the outer atmosphere of a cool star should be treated together, and should not be simply separated as predominantly done so far.

  20. The Origins of Magnetic Structure in the Corona and Wind

    Science.gov (United States)

    Antiochos, Spiro K.

    2010-01-01

    One of the most important and most puzzling features of the coronal magnetic field is that it appears to have smooth magnetic structure with little evidence for non-potentiality except at two special locations: photospheric polarity inversions lines. (non-potentiality observed as a filament channel) and coronal hole boundaries, (observed as the slow solar wind). This characteristic feature of the closed-field corona is highly unexpected given that its magnetic field is continuously tangled by photospheric motions. Although reconnection can eliminate some of the injected structure, it cannot destroy the helicity, which should build up to produce observable complexity. I propose that an inverse cascade process transports the injected helicity from the interior of closed flux regions to their boundaries inversion lines and coronal holes, creating both filament channels and the slow wind. We describe how the helicity is injected and transported and calculate the relevant rates. I argue that one process, helicity transport, can explain both the observed lack and presence of structure in the coronal magnetic field. This work has been supported by the NASA HTP, SR&T, and LWS programs.

  1. Absolute velocity measurements in the solar transition region and corona

    Science.gov (United States)

    Hassler, D. M.; Rottman, G. J.; Orrall, F. Q.

    An experimental technique is presented to measure absolute velocities of minor ions formed in the solar transition region and corona. A sounding rocket experiment July 27 1987 obtained high resolution EUV spectra along a solar diameter with spatial resolution of 20 x 20 arcsec. The wavelengths of the 1533 Si II, 1548 C IV, and 770 Ne VIII emission lines were directly compared with wavelengths of known platinum lines generated by an inflight calibration lamp. On the assumption that horisontal motions cancel statistically so that the line-of-sight velocity approaches zero at the limb, a net radial downflow of approximately 7.5 + or - 1.0 km/s was found for C IV and upper limits were found on the radial flow for Si II and Ne VIII. This assumption was tested by direct comparison to the on-board wavelength reference using recently published laboratory rest wavelengths of the solar emission lines. Agreement was found within the published uncertainties of the laboratory wavelengths + or - 2 km/s in the case of C IV. It is suggested that improved laboratory wavelength measurements (+ or - 1 km/s) in conjunction with inflight wavelength calibration would improve constraints on models of transition region and coronal dynamics.

  2. Errores sistemáticos del Catálogo Fundamental FK5, deducidos de las observaciones con Astrolabio Fotoeléctrico PAII, en el Hemisferio Sur

    Science.gov (United States)

    Manrique, W. T.; Podestá, R. C.; Alonso, E.; Actis, E. V.; Pacheco, A. M.; Bustos, G.; Lizhi, L.; Zezhi, W.; Fanmiao, Z.; Hongqi, W.; Perdomo, R.; González, A.; Gómez, G.

    Se dan los resultados obtenidos de los Errores Sistemáticos del Catálogo Fundamental FK5, Δ α δ, Δ α α, Δ δ α y Δ δ δ, derivados de las observaciones estelares con el Astrolabio Fotoeléctrico PAII del Observatorio de Beijing instalado en el Observatorio Astronómico ``Félix Aguilar'' de San Juan, de acuerdo al Proyecto de Colaboración entre los observatorios de San Juan, Beijing y La Plata. Se han usado los residuos seleccionados de 11000 estrellas aproximadamente, derivados de más de 400000 pasajes estelares en 1550 días, desde Febrero de 1992 a Marzo de 1997. La precisión media de los residuos es de 0,"043.

  3. Orally administered lactoperoxidase increases expression of the FK506 binding protein 5 gene in epithelial cells of the small intestine of mice: a DNA microarray study.

    Science.gov (United States)

    Wakabayashi, Hiroyuki; Miyauchi, Hirofumi; Shin, Kouichirou; Yamauchi, Koji; Matsumoto, Ichiro; Abe, Keiko; Takase, Mitsunori

    2007-09-01

    Lactoperoxidase (LPO) is a component of milk and other external secretions. To study the influence of ingested LPO on the digestive tract, we performed DNA microarray analysis of the small intestine of mice administered LPO. LPO administration upregulated 78 genes, including genes involved in metabolism, immunity, apoptosis, and the cell cycle, and downregulated nine genes, including immunity-related genes. The most upregulated gene was FK506 binding protein 5 (FKBP5), a glucocorticoid regulating immunophilin. The upregulation of this gene was confirmed by quantitative RT-PCR in other samples. In situ hybridization revealed that expression of the FKBP5 gene in the crypt epithelial cells of the small intestine was enhanced by LPO. These results suggest that ingested LPO modulates gene expression in the small intestine and especially increases FKBP5 gene expression in the epithelial cells of the intestine.

  4. Corona cell RNA sequencing from individual oocytes revealed transcripts and pathways linked to euploid oocyte competence and live birth.

    Science.gov (United States)

    Parks, Jason C; Patton, Alyssa L; McCallie, Blair R; Griffin, Darren K; Schoolcraft, William B; Katz-Jaffe, Mandy G

    2016-05-01

    Corona cells surround the oocyte and maintain a close relationship through transzonal processes and gap junctions, and may be used to assess oocyte competence. In this study, the corona cell transcriptome of individual cumulus oocyte complexes (COCs) was investigated. Isolated corona cells were collected from COCs that developed into euploid blastocysts and were transferred in a subsequent frozen embryo transfer. Ten corona cell samples underwent RNA-sequencing to generate unique gene expression profiles. Live birth was compared with negative implantation after the transfer of a euploid blastocyst using bioinformatics and statistical analysis. Individual corona cell samples produced a mean of 21.2 million sequence reads, and 307 differentially expressed transcrpits (P corona cell transcriptome was successfully generated using RNA-sequencing. Key genes and signalling pathways were identified in association with implantation outcome after the transfer of a euploid blastocyst in a frozen embryo transfer. These data could provide novel biomarkers for the non-invasive assessment of embryo viability.

  5. Imp2, the PSTPIP homolog in fission yeast, affects sensitivity to the immunosuppressant FK506 and membrane trafficking in fission yeast

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Ayako; Higa, Mari [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan); Doi, Akira [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan); Japan Society for the Promotion of Science, 1-8 Chiyoda-ku, Tokyo 102-8472 (Japan); Satoh, Ryosuke [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan); Sugiura, Reiko, E-mail: sugiurar@phar.kindai.ac.jp [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan)

    2015-02-13

    Cytokinesis is a highly ordered process that divides one cell into two cells, which is functionally linked to the dynamic remodeling of the plasma membrane coordinately with various events such as membrane trafficking. Calcineurin is a highly conserved serine/threonine protein phosphatase, which regulates multiple biological functions, such as membrane trafficking and cytokinesis. Here, we isolated imp2-c3, a mutant allele of the imp2{sup +} gene, encoding a homolog of the mouse PSTPIP1 (proline-serine-threonine phosphatase interacting protein 1), using a genetic screen for mutations that are synthetically lethal with calcineurin deletion in fission yeast. The imp2-c3 mutants showed a defect in cytokinesis with multi-septated phenotypes, which was further enhanced upon treatment with the calcineurin inhibitor FK506. Notably, electron micrographs revealed that the imp2-c3 mutant cells accumulated aberrant multi-lamella Golgi structures and putative post-Golgi secretory vesicles, and exhibited fragmented vacuoles in addition to thickened septa. Consistently, imp2-c3 mutants showed a reduced secretion of acid phosphatase and defects in vacuole fusion. The imp2-c3 mutant cells exhibited a weakened cell wall, similar to the membrane trafficking mutants identified in the same genetic screen such as ypt3-i5. These findings implicate the PSTPIP1 homolog Imp2 in Golgi/vacuole function, thereby affecting various cellular processes, including cytokinesis and cell integrity. - Highlights: • We isolated imp2-c3, in a synthetic lethal screen with calcineurin in fission yeast. • The imp2{sup +} gene encodes a component of the actin contractile ring similar to Cdc15. • The imp2-c3 mutants showed defects in cytokinesis, which were exacerbated by FK506. • The imp2-c3 mutants were defective in membrane trafficking and cell wall integrity. • Our study revealed a novel role for Imp2 in the Golgi/vacuolar membrane trafficking.

  6. High Performance Computing Application: Solar Dynamo Model Project II, Corona and Heliosphere Component Initialization, Integration and Validation

    Science.gov (United States)

    2015-06-24

    allocate solar heating into any location of the corona . Its total contribution depended on the integration of the unsigned magnetic flux at 1 Rs...AFRL-RD-PS- TR-2015-0028 AFRL-RD-PS- TR-2015-0028 HIGH PERFORMANCE COMPUTING APPLICATION: SOLAR DYNAMO MODEL PROJECT II; CORONA AND HELIOSPHERE...Dynamo Model Project II, Corona and Heliosphere Component Initialization, Integration and Validation 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  7. Numerical modelling of ozone production in a wire-cylinder corona discharge and comparison with a wire-plate corona discharge

    Science.gov (United States)

    Wang, Pengxiang; Chen, Junhong

    2009-02-01

    The effect of electrode configuration on ozone production in the direct-current corona discharge of dry and humid air is studied by a numerical model that combines the electron distribution in the corona plasma, plasma chemistry and transport phenomena. Two electrode configurations are considered: wire-cylinder discharge with air flowing along the wire axis and wire-plate discharge with air flowing transverse to the wire. The ozone distributions in both types of discharges are compared. For both electrode configurations, the ozone production rate is higher in the negative corona than in the positive corona and it decreases with an increase in relative humidity. More importantly, the detailed ozone distribution in the neighbourhood of the discharge wire, together with the ozone kinetics, reveals the possible difference in the ozone production from the two discharges. With the same operating conditions and sufficiently short flow residence time, the ozone production rate is nearly the same for both electrode configurations. When the flow residence time is longer than the characteristic time for homogeneous ozone destruction, the net ozone production is higher in the wire-cylinder discharge than in the wire-plate discharge due to relatively less ozone destruction.

  8. The Effects of Corona on Current Surges Induced on Conducting Lines by EMP (Electromagnetic Pulse): A Comparison of Experiment Data with Results of Analytic Corona Models

    Science.gov (United States)

    1987-09-01

    265-281. 18. Rogers , S.R., and R.A. Perala, "The Effects of Corona and Angle of Arrival on the EMP Response of Cables Lying on the Surface of the...Survivability Organization, Boeing Aerospace COmpany, P. 0. Box 399, Seattle, WA 98124 74. V. L. Chartier , Bonneville Power Administration, P. 0. Box

  9. Preparation of Core-Shell Hybrid Materials by Producing a Protein Corona Around Magnetic Nanoparticles

    Science.gov (United States)

    Weidner, A.; Gräfe, C.; von der Lühe, M.; Remmer, H.; Clement, J. H.; Eberbeck, D.; Ludwig, F.; Müller, R.; Schacher, F. H.; Dutz, S.

    2015-07-01

    Nanoparticles experience increasing interest for a variety of medical and pharmaceutical applications. When exposing nanomaterials, e.g., magnetic iron oxide nanoparticles (MNP), to human blood, a protein corona consisting of various components is formed immediately. The composition of the corona as well as its amount bound to the particle surface is dependent on different factors, e.g., particle size and surface charge. The actual composition of the formed protein corona might be of major importance for cellular uptake of magnetic nanoparticles. The aim of the present study was to analyze the formation of the protein corona during in vitro serum incubation in dependency of incubation time and temperature. For this, MNP with different shells were incubated in fetal calf serum (FCS, serving as protein source) within a water bath for a defined time and at a defined temperature. Before and after incubation the particles were characterized by a variety of methods. It was found that immediately (seconds) after contact of MNP and FCS, a protein corona is formed on the surface of MNP. This formation led to an increase of particle size and a slight agglomeration of the particles, which was relatively constant during the first minutes of incubation. A longer incubation (from hours to days) resulted in a stronger agglomeration of the FCS incubated MNP. Quantitative analysis (gel electrophoresis) of serum-incubated particles revealed a relatively constant amount of bound proteins during the first minutes of serum incubation. After a longer incubation (>20 min), a considerably higher amount of surface proteins was determined for incubation temperatures below 40 °C. For incubation temperatures above 50 °C, the influence of time was less significant which might be attributed to denaturation of proteins during incubation. Overall, analysis of the molecular weight distribution of proteins found in the corona revealed a clear influence of incubation time and temperature on corona

  10. The fate of a designed protein corona on nanoparticles in vitro and in vivo

    Directory of Open Access Journals (Sweden)

    Denise Bargheer

    2015-01-01

    Full Text Available A variety of monodisperse superparamagnetic iron oxide particles (SPIOs was designed in which the surface was modified by PEGylation with mono- or bifunctional poly(ethylene oxideamines (PEG. Using 125I-labeled test proteins (transferrin, albumin, the binding and exchange of corona proteins was studied first in vitro. Incubation with 125I-transferrin showed that with increasing grade of PEGylation the binding was substantially diminished without a difference between simply adsorbed and covalently bound protein. However, after incubation with excess albumin and subsequently whole plasma, transferrin from the preformed transferrin corona was more and more lost from SPIOs in the case of adsorbed proteins. If non-labeled transferrin was used as preformed corona and excess 125I-labeled albumin was added to the reaction mixtures with different SPIOs, a substantial amount of label was bound to the particles with initially adsorbed transferrin but little or even zero with covalently bound transferrin. These in vitro experiments show a clear difference in the stability of a preformed hard corona with adsorbed or covalently bound protein. This difference seems, however, to be of minor importance in vivo when polymer-coated 59Fe-SPIOs with adsorbed or covalently bound 125I-labeled mouse transferrin were injected intravenously in mice. With both protein coronae the 59Fe/125I-labelled particles were cleared from the blood stream within 30 min and appeared in the liver and spleen to a large extent (>90%. In addition, after 2 h already half of the 125I-labeled transferrin from both nanodevices was recycled back into the plasma and into tissue. This study confirms that adsorbed transferrin from a preformed protein corona is efficiently taken up by cells. It is also highlighted that a radiolabelling technique described in this study may be of value to investigate the role of protein corona formation in vivo for the respective nanoparticle uptake.

  11. Preliminary protein corona formation stabilizes gold nanoparticles and improves deposition efficiency

    Science.gov (United States)

    Luby, Alexandra O.; Breitner, Emily K.; Comfort, Kristen K.

    2016-08-01

    Due to their advantageous characteristics, gold nanoparticles (AuNPs) are being increasingly utilized in a vast array of biomedical applications. However, the efficacy of these procedures are highly dependent upon strong interactions between AuNPs and the surrounding environment. While the field of nanotechnology has grown exponentially, there is still much to be discovered with regards to the complex interactions between NPs and biological systems. One area of particular interest is the generation of a protein corona, which instantaneously forms when NPs encounter a protein-rich environment. Currently, the corona is viewed as an obstacle and has been identified as the cause for loss of application efficiency in physiological systems. To date, however, no study has explored if the protein corona could be designed and advantageously utilized to improve both NP behavior and application efficacy. Therefore, we sought to identify if the formation of a preliminary protein corona could modify both AuNP characteristics and association with the HaCaT cell model. In this study, a corona comprised solely of epidermal growth factor (EGF) was successfully formed around 10-nm AuNPs. These EGF-AuNPs demonstrated augmented particle stability, a modified corona composition, and increased deposition over stock AuNPs, while remaining biocompatible. Analysis of AuNP dosimetry was repeated under dynamic conditions, with lateral flow significantly disrupting deposition and the nano-cellular interface. Taken together, this study demonstrated the plausibility and potential of utilizing the protein corona as a means to influence NP behavior; however, fluid dynamics remains a major challenge to progressing NP dosimetry.

  12. Revisiting the Structure and Spectrum of the Magnetic-reconnection-heated Corona in Luminous AGNs

    Science.gov (United States)

    Liu, J. Y.; Qiao, E. L.; Liu, B. F.

    2016-12-01

    It is believed that the hard X-ray emission in the luminous active galactic nuclei (AGNs) is from the hot corona above the cool accretion disk. However, the formation of the corona is still debated. Liu et al. investigated the spectrum of the corona heated by the reconnection of the magnetic field generated by dynamo action in the thin disk and emerging into the corona as a result of buoyancy instability. In the present paper, we improve this model to interpret the observed relation of the hard X-ray spectrum becoming softer at higher accretion rate in luminous AGNs. The magnetic field is characterized by {β }0, i.e., the ratio of the sum of gas pressure and radiation pressure to the magnetic pressure in the disk ({β }0=({P}g,d+{P}r,d)/{P}B). Besides, both the intrinsic disk photons and reprocessed photons by the disk are included as the seed photons for inverse Compton scattering. These improvements are crucial for investigating the effect of magnetic field on the accretion disk corona when it is not clear whether the radiation pressure or gas pressure dominates in the thin disk. We change the value of {β }0 in order to constrain the magnetic field in the accretion disk in luminous AGNs. We find that the energy fraction released in the corona (f) gradually increases with the decrease of {β }0 for the same accretion rate. When {β }0 decreases to less than 50, the structure and spectrum of the disk corona are independent of accretion rate, which is similar to the hard spectrum found in Liu et al. Comparing with the observational results of the hard X-ray bolometric correction factor in a sample of luminous AGNs, we suggest that the value of {β }0 is about 100-200 for α = 0.3, and the energy fraction f should be larger than 30% for hard X-ray emission.

  13. Preparation of Core-Shell Hybrid Materials by Producing a Protein Corona Around Magnetic Nanoparticles.

    Science.gov (United States)

    Weidner, A; Gräfe, C; von der Lühe, M; Remmer, H; Clement, J H; Eberbeck, D; Ludwig, F; Müller, R; Schacher, F H; Dutz, S

    2015-12-01

    Nanoparticles experience increasing interest for a variety of medical and pharmaceutical applications. When exposing nanomaterials, e.g., magnetic iron oxide nanoparticles (MNP), to human blood, a protein corona consisting of various components is formed immediately. The composition of the corona as well as its amount bound to the particle surface is dependent on different factors, e.g., particle size and surface charge. The actual composition of the formed protein corona might be of major importance for cellular uptake of magnetic nanoparticles. The aim of the present study was to analyze the formation of the protein corona during in vitro serum incubation in dependency of incubation time and temperature. For this, MNP with different shells were incubated in fetal calf serum (FCS, serving as protein source) within a water bath for a defined time and at a defined temperature. Before and after incubation the particles were characterized by a variety of methods. It was found that immediately (seconds) after contact of MNP and FCS, a protein corona is formed on the surface of MNP. This formation led to an increase of particle size and a slight agglomeration of the particles, which was relatively constant during the first minutes of incubation. A longer incubation (from hours to days) resulted in a stronger agglomeration of the FCS incubated MNP. Quantitative analysis (gel electrophoresis) of serum-incubated particles revealed a relatively constant amount of bound proteins during the first minutes of serum incubation. After a longer incubation (>20 min), a considerably higher amount of surface proteins was determined for incubation temperatures below 40 °C. For incubation temperatures above 50 °C, the influence of time was less significant which might be attributed to denaturation of proteins during incubation. Overall, analysis of the molecular weight distribution of proteins found in the corona revealed a clear influence of incubation time and temperature on

  14. The fate of a designed protein corona on nanoparticles in vitro and in vivo.

    Science.gov (United States)

    Bargheer, Denise; Nielsen, Julius; Gébel, Gabriella; Heine, Markus; Salmen, Sunhild C; Stauber, Roland; Weller, Horst; Heeren, Joerg; Nielsen, Peter

    2015-01-01

    A variety of monodisperse superparamagnetic iron oxide particles (SPIOs) was designed in which the surface was modified by PEGylation with mono- or bifunctional poly(ethylene oxide)amines (PEG). Using (125)I-labeled test proteins (transferrin, albumin), the binding and exchange of corona proteins was studied first in vitro. Incubation with (125)I-transferrin showed that with increasing grade of PEGylation the binding was substantially diminished without a difference between simply adsorbed and covalently bound protein. However, after incubation with excess albumin and subsequently whole plasma, transferrin from the preformed transferrin corona was more and more lost from SPIOs in the case of adsorbed proteins. If non-labeled transferrin was used as preformed corona and excess (125)I-labeled albumin was added to the reaction mixtures with different SPIOs, a substantial amount of label was bound to the particles with initially adsorbed transferrin but little or even zero with covalently bound transferrin. These in vitro experiments show a clear difference in the stability of a preformed hard corona with adsorbed or covalently bound protein. This difference seems, however, to be of minor importance in vivo when polymer-coated (59)Fe-SPIOs with adsorbed or covalently bound (125)I-labeled mouse transferrin were injected intravenously in mice. With both protein coronae the (59)Fe/(125)I-labelled particles were cleared from the blood stream within 30 min and appeared in the liver and spleen to a large extent (>90%). In addition, after 2 h already half of the (125)I-labeled transferrin from both nanodevices was recycled back into the plasma and into tissue. This study confirms that adsorbed transferrin from a preformed protein corona is efficiently taken up by cells. It is also highlighted that a radiolabelling technique described in this study may be of value to investigate the role of protein corona formation in vivo for the respective nanoparticle uptake.

  15. Laboratory identification of MHD eruption criteria in the solar corona

    Science.gov (United States)

    Myers, Clayton E.

    2015-11-01

    Ideal magnetohydrodynamic (MHD) instabilities such as the kink and torus instabilities are believed to play an important role in driving ``storage-and-release'' eruptions in the solar corona. These instabilities act on long-lived, arched magnetic flux ropes that are ``line-tied'' to the solar surface. In spite of numerous observational and computational studies, the conditions under which these instabilities produce an eruption remain a subject of intense debate. In this paper, we use a line-tied, arched flux rope experiment to study storage-and-release eruptions in the laboratory. An in situ array of miniature magnetic probes is used to assess the equilibrium and stability of the laboratory flux ropes. Two major results are reported here: First, a new stability regime is identified where torus-unstable flux ropes fail to erupt. In this ``failed torus'' regime, the flux rope is torus-unstable but kink-stable. Under these conditions, a dynamic ``toroidal field tension force'' surges in magnitude, causing the flux rope to contract. This tension force, which is missing from existing eruption models, is the J × B force between self-generated poloidal currents in the flux rope and the toroidal (guide) component of the vacuum field. Secondly, a clear torus instability threshold is observed in the kink-unstable regime. This latter result, which is consistent with existing theoretical and numerical results, verifies the key role of the torus instability in driving solar eruptions. In collaboration with M. Yamada, H. Ji, J. Yoo, W. Fox, J. Jara-Almonte, A. Savcheva, and E. E. DeLuca. This research is supported by DoE Contract No. DE-AC02-09CH11466 and by the NSF/DoE Center for Magnetic Self-Organization (CMSO).

  16. Intensity dependence of electron gas kinetics in a laser corona

    Directory of Open Access Journals (Sweden)

    Mašek Martin

    2013-11-01

    Full Text Available In various experimental situations relevant to the laser fusion, such as plasma near the light entrance holes of hohlraum in the indirect drive experiments or more recently in the shock ignition direct drive a relatively long underdense plasma of corona type is encountered, which is subject to an intense nanosecond laser beam. The plasma is only weakly collisional and thus in the electron phase space a complicated kinetic evolution is going on, which is taking the electron gas fairly far from the thermal equilibrium and contributes to its unstable behaviour. These phenomena impede the absorption and thermalization of the incoming laser energy, create groups of fast electrons and also may lead to a non-linear reflection of the heating laser beam. One of the key processes leading to the electron acceleration is the stimulated Raman scattering (SRS in its non-linear phase. The SRS in the presence of electron-ion collisions requires a certain threshold intensity above which the mentioned non-dissipative phenomena can occur and develop to the stage, where they may become unpleasant for the fusion experiments. To assess this intensity limit a computational model has been developed based on the Vlasov-Maxwell kinetics describing such a plasma in 1D geometry. At a relatively high intensity of 1016 W/cm2 a number of non-linear phenomena are predicted by the code such as a saturation of Landau damping, which is then translated in an unfavourable time dependence of the reflected light intensity and formation of accelerated electron groups due to the electron trapping. The purpose of the present contribution is to map the intensity dependence of this non-linear development with the aim of assessing its weight in fusion relevant situations.

  17. Analysis of non-thermal velocities in the solar corona

    Directory of Open Access Journals (Sweden)

    L. Contesse

    2004-09-01

    Full Text Available We describe new ground-based spectroscopic observations made using a 40-cm aperture coronagraph over a whole range of radial distances (up to heights of 12' above the limb and along four different heliocentric directions N, E, S and W. The analysis is limited to the study of the brightest forbidden emission line of Fe XIV at 530.3nm, in order to reach the best possible signal-to-noise ratio. To make the results statistically more significant, the extracted parameters are averaged over the whole length of the slit, and measurements are repeated fives times at each position; the corresponding dispersions in the results obtained along the slit are given. Central line profile intensities and full line widths (FWHM are plotted and compared to measurements published by other authors closer to the limb. We found widths and turbulent (non-thermal velocities of significantly higher values above the polar regions, especially when a coronal hole is present along the line of sight. We do not see a definitely decreasing behaviour of widths and turbulent velocities in equatorial directions for larger radial distances, as reported in the literature, although lower values are measured compared to the values in polar regions. The variation in the high corona is rather flat and a correlation diagram indicates that it is different for different regions and different radial distances. This seems to be the first analysis of the profiles of this coronal line, up to large heights above the limb for both equatorial and polar regions.

  18. The Writhe of Helical Structures in the Solar Corona

    Science.gov (United States)

    Toeroek, T.; Berger, M. A.; Kliem, B.

    2010-01-01

    Context. Helicity is a fundamental property of magnetic fields, conserved in ideal MHD. In flux rope topology, it consists of twist and writhe helicity. Despite the common occurrence of helical structures in the solar atmosphere, little is known about how their shape relates to the writhe, which fraction of helicity is contained in writhe, and how much helicity is exchanged between twist and writhe when they erupt. Aims. Here we perform a quantitative investigation of these questions relevant for coronal flux ropes. Methods. The decomposition of the writhe of a curve into local and nonlocal components greatly facilitates its computation. We use it to study the relation between writhe and projected S shape of helical curves and to measure writhe and twist in numerical simulations of flux rope instabilities. The results are discussed with regard to filament eruptions and coronal mass ejections (CMEs). Results. (1) We demonstrate that the relation between writhe and projected S shape is not unique in principle, but that the ambiguity does not affect low-lying structures, thus supporting the established empirical rule which associates stable forward (reverse) S shaped structures low in the corona with positive (negative) helicity. (2) Kink-unstable erupting flux ropes are found to transform a far smaller fraction of their twist helicity into writhe helicity than often assumed. (3) Confined flux rope eruptions tend to show stronger writhe at low heights than ejective eruptions (CMEs). This argues against suggestions that the writhing facilitates the rise of the rope through the overlying field. (4) Erupting filaments which are S shaped already before the eruption and keep the sign of their axis writhe (which is expected if field of one chirality dominates the source volume of the eruption), must reverse their S shape in the course of the rise. Implications for the occurrence of the helical kink instability in such events are discussed.

  19. Multiscale simulation of DC corona discharge and ozone generation from nanostructures

    Science.gov (United States)

    Wang, Pengxiang

    Atmospheric direct current (dc) corona discharge from micro-sized objects has been widely used as an ion source in many devices, such as photocopiers, laser printers, and electronic air cleaners. Shrinking the size of the discharge electrode to the nanometer range (e.g., through the use of carbon nanotubes or CNTs) is expected to lead to a significant reduction in power consumption and detrimental ozone production in these devices. The objectives of this study are to unveil the fundamental physics of the nanoscale corona discharge and to evaluate its performance and ozone production through numerical models. The extremely small size of CNTs presents considerable complexity and challenges in modeling CNT corona discharges. A hybrid multiscale model, which combines a kinetic particle-in-cell plus Monte Carlo collision (PIC-MCC) model and a continuum model, is developed to simulate the corona discharge from nanostructures. The multiscale model is developed in several steps. First, a pure PIC-MCC model is developed and PIC-MCC simulations of corona plasma from micro-sized electrode with same boundary conditions as prior model are performed to validate the PIC-MCC scheme. The agreement between the PIC-MCC model and the prior continuum model indicates the validity of the PIC-MCC scheme. The validated PIC-MCC scheme is then coupled with a continuum model to simulate the corona discharge from a micro-sized electrode. Unlike the prior continuum model which only predicts the corona plasma region, the hybrid model successfully predicts the self-consistent discharge process in the entire corona discharge gap that includes both corona plasma region and unipolar ion region. The voltage-current density curves obtained by the hybrid model agree well with analytical prediction and experimental results. The hybrid modeling approach, which combines the accuracy of a kinetic model and the efficiency of a continuum model, is thus validated for modeling dc corona discharges. For

  20. A semi-analytical study of positive corona discharge in wire-plane electrode configuration

    Science.gov (United States)

    Yanallah, K.; Pontiga, F.; Chen, J. H.

    2013-08-01

    Wire-to-plane positive corona discharge in air has been studied using an analytical model of two species (electrons and positive ions). The spatial distributions of electric field and charged species are obtained by integrating Gauss's law and the continuity equations of species along the Laplacian field lines. The experimental values of corona current intensity and applied voltage, together with Warburg's law, have been used to formulate the boundary condition for the electron density on the corona wire. To test the accuracy of the model, the approximate electric field distribution has been compared with the exact numerical solution obtained from a finite element analysis. A parametrical study of wire-to-plane corona discharge has then been undertaken using the approximate semi-analytical solutions. Thus, the spatial distributions of electric field and charged particles have been computed for different values of the gas pressure, wire radius and electrode separation. Also, the two dimensional distribution of ozone density has been obtained using a simplified plasma chemistry model. The approximate semi-analytical solutions can be evaluated in a negligible computational time, yet provide precise estimates of corona discharge variables.

  1. Positive direct current corona discharges in single wire-duct electrostatic precipitators

    Directory of Open Access Journals (Sweden)

    Ashraf Yehia

    2016-05-01

    Full Text Available This paper is aimed to study the characteristics of the positive dc corona discharges in single wire-duct electrostatic precipitators. Therefore, the corona discharges were formed inside dry air fed single wire-duct reactor under positive dc voltage at the normal atmospheric conditions. The corona current-voltage characteristics curves have been measured in parallel with the ozone concentration generated inside the reactor under different discharge conditions. The corona current-voltage characteristics curves have agreed with a semi empirical equation derived from the previous studies. The experimental results of the ozone concentration generated inside the reactor were formulated in the form of an empirical equation included the different parameters that were studied experimentally. The obtained equations are valid to expect both the current-voltage characteristics curves and the corresponding ozone concentration that generates with the positive dc corona discharges inside single wire-duct electrostatic precipitators under any operating conditions in the same range of the present study.

  2. [Research on electron density in DC needle-plate corona discharge at atmospheric pressure].

    Science.gov (United States)

    Liu, Zhi-Qiang; Guo, Wei; Liu, Tao-Tao; Wu, Wen-Shuo; Liu, Shu-Min

    2013-11-01

    Using needle-plate discharge device, corona discharge experiment was done in the atmosphere. Through photo of spot size of light-emitting area, the relationship between the voltage and thickness of corona layer was discussed. When the distance between tip and plate is fixed, the thickness of corona layer increases with the increase in voltage; when the voltage is fixed, the thickness of corona layer decreases with the increase in the distance between tip and plate. As spectral intensity of N2 (C3pi(u)) (337.1 nm)reflects high energy electron density, it was measured with emission spectrometry. The results show that high energy electron density is the biggest near the needle tip and the relationship between high energy electron density and voltage is basically linear increasing. Fixing voltage, high energy electron density decreases with the increase in the distance between tip and plate. When the voltage and the distance between tip and plate are fixed, the high energy electron density increases with the decrease in the curvature radius of needle tip. These results are of great importance for the study of plasma parameters of corona discharge.

  3. Experimental Investigation of the Corona Discharge in Electrical Transmission due to AC/DC Electric Fields

    Directory of Open Access Journals (Sweden)

    Fuangpian Phanupong

    2016-01-01

    Full Text Available Nowadays, using of High Voltage Direct Current (HVDC transmission to maximize the transmission efficiency, bulk power transmission, connection of renewable power source from wind farm to the grid is of prime concern for the utility. However, due to the high electric field stress from Direct Current (DC line, the corona discharge can easily be occurred at the conductor surface leading to transmission loss. Therefore, the polarity effect of DC lines on corona inception and breakdown voltage should be investigated. In this work, the effect of DC polarity and Alternating Current (AC field stress on corona inception voltage and corona discharge is investigated on various test objects, such as High Voltage (HV needle, needle at ground plane, internal defect, surface discharge, underground cable without cable termination, cable termination with simulated defect and bare overhead conductor. The corona discharge is measured by partial discharge measurement device with high-frequency current transformer. Finally, the relationship between supply voltage and discharge intensity on each DC polarity and AC field stress can be successfully determined.

  4. Effects of the corona pretreatment of PET substrates on the properties of flexible transparent CNT electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sang-Hoon; Kim, Bu-Jong; Park, Jin-Seok

    2014-12-01

    In this study, the effects of substrate pretreatment on the properties of carbon nanotubes (CNTs), which are used as flexible transparent electrodes, were investigated. CNTs were deposited on PET (polyethylene terephthalate) substrates using a spray coating method. Prior to the deposition of the CNTs, the PET substrates were corona-treated by varying the feeding directions of the PET substrate and the number of treatments. The variation in the surface morphology and roughness of the PET substrates due to the corona pretreatment were characterized via atomic force microscopy (AFM). The contact angles of the PET substrates were measured using polar and dispersive liquids, and the surface energies were estimated. Also, the sheet resistance of the CNTs deposited on the PET substrates was measured before and after the bending test. The experiment results provided strong evidence that the adhesive forces between the CNTs and the PET substrate can be substantially enhanced by corona pretreatment. - Highlights: • The surfaces of PET substrates have been treated via corona plasma. • The surface roughness and contact angle of PET substrate have been measured. • The effects of corona-treatment on the surface energy of PETs have been analyzed. • CNTs have been deposited on PET substrates using a spray coating method. • The variation in the sheet resistance of CNTs due to bending has been examined.

  5. Efficiency of gas cooling and accretion at the disc-corona interface

    Science.gov (United States)

    Armillotta, L.; Fraternali, F.; Marinacci, F.

    2016-11-01

    In star-forming galaxies, stellar feedback can have a dual effect on the circumgalactic medium both suppressing and stimulating gas accretion. The trigger of gas accretion can be caused by disc material ejected into the halo in the form of fountain clouds and by its interaction with the surrounding hot corona. Indeed, at the disc-corona interface, the mixing between the cold/metal-rich disc gas (T ≲ 104 K) and the hot coronal gas (T ≳ 106 K) can dramatically reduce the cooling time of a portion of the corona and produce its condensation and accretion. We studied the interaction between fountain clouds and corona in different galactic environments through parsec-scale hydrodynamical simulations, including the presence of thermal conduction, a key mechanism that influences gas condensation. Our simulations showed that the coronal gas condensation strongly depends on the galactic environment, in particular it is less efficient for increasing virial temperature/mass of the haloes where galaxies reside and it is fully ineffective for objects with virial masses larger than 1013 M⊙. This result implies that the coronal gas cools down quickly in haloes with low-intermediate virial mass (Mvir ≲ 3 × 1012 M⊙) but the ability to cool the corona decreases going from late-type to early-type disc galaxies, potentially leading to the switching off of accretion and the quenching of star formation in massive systems.

  6. Modeling the time evolution of the nanoparticle-protein corona in a body fluid.

    Directory of Open Access Journals (Sweden)

    Daniele Dell'Orco

    Full Text Available BACKGROUND: Nanoparticles in contact with biological fluids interact with proteins and other biomolecules, thus forming a dynamic corona whose composition varies over time due to continuous protein association and dissociation events. Eventually equilibrium is reached, at which point the continued exchange will not affect the composition of the corona. RESULTS: We developed a simple and effective dynamic model of the nanoparticle protein corona in a body fluid, namely human plasma. The model predicts the time evolution and equilibrium composition of the corona based on affinities, stoichiometries and rate constants. An application to the interaction of human serum albumin, high density lipoprotein (HDL and fibrinogen with 70 nm N-iso-propylacrylamide/N-tert-butylacrylamide copolymer nanoparticles is presented, including novel experimental data for HDL. CONCLUSIONS: The simple model presented here can easily be modified to mimic the interaction of the nanoparticle protein corona with a novel biological fluid or compartment once new data will be available, thus opening novel applications in nanotoxicity and nanomedicine.

  7. Outflow structure of the quiet sun corona probed by spacecraft radio scintillations in strong scattering

    Energy Technology Data Exchange (ETDEWEB)

    Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki; Nakamura, Masato [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Tokumaru, Munetoshi; Shiota, Daikou [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 484-8601 (Japan); Isobe, Hiroaki; Asai, Ayumi [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto 607-8471, Japan. (Japan); Miyamoto, Mayu [Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Häusler, Bernd [Institut für Raumfahrttechnik, Universität der Bundeswehr München, D-85577 Neubiberg (Germany); Pätzold, Martin [Rheinisches Institut für Umweltforschung, Department Planetenforschung, Universität zu Köln, Aachener Strasse 209, D-50931 Köln (Germany); Nabatov, Alexander [The Institute of Radio Astronomy, National Academy of Science of Ukraine, Chervonoprapornaya, Strasse 4, Kharkov 61002 (Ukraine); Yaji, Kentaro [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Yamada, Manabu, E-mail: imamura.takeshi@jaxa.jp [Planetary Exploration Research Center, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016 (Japan)

    2014-06-20

    Radio scintillation observations have been unable to probe flow speeds in the low corona where the scattering of radio waves is exceedingly strong. Here we estimate outflow speeds continuously from the vicinity of the Sun to the outer corona (heliocentric distances of 1.5-20.5 solar radii) by applying the strong scattering theory to radio scintillations for the first time, using the Akatsuki spacecraft as the radio source. Small, nonzero outflow speeds were observed over a wide latitudinal range in the quiet-Sun low corona, suggesting that the supply of plasma from closed loops to the solar wind occurs over an extended area. The existence of power-law density fluctuations down to the scale of 100 m was suggested, which is indicative of well-developed turbulence which can play a key role in heating the corona. At higher altitudes, a rapid acceleration typical of radial open fields is observed, and the temperatures derived from the speed profile show a distinct maximum in the outer corona. This study opened up a possibility of observing detailed flow structures near the Sun from a vast amount of existing interplanetary scintillation data.

  8. Variation of protein corona composition of gold nanoparticles following plasmonic heating.

    Science.gov (United States)

    Mahmoudi, Morteza; Lohse, Samuel E; Murphy, Catherine J; Fathizadeh, Arman; Montazeri, Abbas; Suslick, Kenneth S

    2014-01-08

    It is well recognized that the primary interaction of most biological environments with nanoparticles (NPs) is strongly influenced by a long-lived ("hard") protein corona that surrounds the NP and remains strongly adsorbed to its surface. The amount and composition of associated proteins in the corona adsorbed onto the NPs is related to several important factors, including the physicochemical properties of the NPs and the composition of the protein solution. Here, for the first time, it is shown that plasmonic heat induction (by laser activation) leads to significant changes in the composition of the hard protein corona adsorbed on low aspect ratio gold nanorods. Using mass spectrometry, several proteins in the corona were identified whose concentrations change most substantially as a result of photoinduced (plasmonic) heating versus simple thermal heating. Molecular modeling suggests that the origin of these changes in protein adsorption may be the result of protein conformational changes in response to much higher local temperatures that occur near the gold nanorods during photoinduced, plasmonic heating. These results may define new applications in vivo for NPs with hyperthermia capability and better define the likely interactions of cells with NPs after plasmonic heating. Potential changes in the protein corona following hyperthermia treatment may influence the final biological fate of plasmonic NPs in clinical applications and help elucidate safety considerations for hyperthermia applications.

  9. Nanoparticle size matters in the formation of plasma protein coronas on Fe3O4 nanoparticles.

    Science.gov (United States)

    Hu, Zhengyan; Zhang, Hongyan; Zhang, Yi; Wu, Ren'an; Zou, Hanfa

    2014-09-01

    When nanoparticles (NPs) enter into biological systems, proteins would interact with NPs to form the protein corona that can critically impact the biological identity of the nanomaterial. Owing to their fundamental scientific interest and potential applications, Fe3O4 NPs of different sizes have been developed for applications in cell separation and protein separation and as contrast agents in magnetic resonance imaging (MRI), etc. Here, we investigated whether nanoparticle size affects the formation of protein coronas around Fe3O4 NPs. Both the identification and quantification results demonstrated that particle size does play an important role in the formation of plasma protein coronas on Fe3O4 NPs; it not only influenced the protein composition of the formed plasma protein corona but also affected the abundances of the plasma proteins within the coronas. Understanding the different binding profiles of human plasma proteins on Fe3O4 NPs of different sizes would facilitate the exploration of the bio-distributions and biological fates of Fe3O4 NPs in biological systems.

  10. The timeline of corona formation around silica nanocarriers highlights the role of the protein interactome.

    Science.gov (United States)

    Pisani, Cédric; Gaillard, Jean-Charles; Odorico, Michaël; Nyalosaso, Jeff L; Charnay, Clarence; Guari, Yannick; Chopineau, Joël; Devoisselle, Jean-Marie; Armengaud, Jean; Prat, Odette

    2017-02-02

    Magnetic mesoporous silica nanoparticles (M-MSNs) represent promising targeting tools for theranostics. Engineering the interaction of nanoparticles (NPs) with biological systems requires an understanding of protein corona formation around the nanoparticles as this drives the biological fate of nanocarriers. We investigated the behavior of proteins in contact with M-MSNs by high-throughput comparative proteomics, using human and bovine sera as biological fluids, in order to assess the adsorption dynamics of proteins in these media. Using system biology tools, and especially protein-protein interaction databases, we demonstrated how the protein network builds up within the corona over the course of the experiment. Based on these results, we introduce and discuss the role of the "corona interactome" as an important factor influencing protein corona evolution. The concept of the "corona interactome" is an original methodology which could be generalized to all NP candidates. Based on this, pre-coating nanocarriers with specific proteins presenting minimal interactions with opsonins might provide them with properties such as stealth.

  11. Personalized liposome-protein corona in the blood of breast, gastric and pancreatic cancer patients.

    Science.gov (United States)

    Colapicchioni, Valentina; Tilio, Martina; Digiacomo, Luca; Gambini, Valentina; Palchetti, Sara; Marchini, Cristina; Pozzi, Daniela; Occhipinti, Sergio; Amici, Augusto; Caracciolo, Giulio

    2016-06-01

    When nanoparticles (NPs) are dispersed in a biofluid, they are covered by a protein corona the composition of which strongly depends on the protein source. Recent studies demonstrated that the type of disease has a crucial role in the protein composition of the NP corona with relevant implications on personalized medicine. Proteomic variations frequently occur in cancer with the consequence that the bio-identity of NPs in the blood of cancer patients may differ from that acquired after administration to healthy volunteers. In this study we investigated the correlation between alterations of plasma proteins in breast, gastric and pancreatic cancer and the biological identity of clinically approved AmBisome-like liposomes as determined by a combination of dynamic light scattering, zeta potential analysis, one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (1D-SDS-PAGE) and semi-quantitative densitometry. While size of liposome-protein complexes was not significantly different between cancer groups, the hard corona from pancreatic cancer patients was significantly less negatively charged. Of note, the hard corona from pancreatic cancer patients was more enriched than those of other cancer types this enrichment being most likely due to IgA and IgG with possible correlations with the autoantibodies productions in cancer. Given the strict relationship between tumor antigen-specific autoantibodies and early cancer detection, our results could be the basis for the development of novel nanoparticle-corona-based screening tests of cancer.

  12. The Intracellular Destiny of the Protein Corona: A Study on its Cellular Internalization and Evolution.

    Science.gov (United States)

    Bertoli, Filippo; Garry, David; Monopoli, Marco P; Salvati, Anna; Dawson, Kenneth A

    2016-11-22

    It has been well established that the early stages of nanoparticle-cell interactions are governed, at least in part, by the layer of proteins and other biomolecules adsorbed and slowly exchanged with the surrounding biological media (biomolecular corona). Subsequent to membrane interactions, nanoparticles are typically internalized into the cell and trafficked along defined pathways such as, in many cases, the endolysosomal pathway. Indeed, if the original corona is partially retained on the nanoparticle surface, the biomolecules in this layer may play an important role in determining subsequent cellular processing. In this work, using a combination of organelle separation and fluorescence labeling of the initial extracellular corona, we clarify its intracellular evolution as nanoparticles travel within the cell. We show that specific proteins present in the original protein corona are retained on the nanoparticles until they accumulate in lysosomes, and, once there, they are degraded. We also report on how different bare surfaces (amino and carboxyl modified) affect the details of this evolution. One overarching discovery is that the same serum proteins can exhibit different intracellular processing when carried inside cells by nanoparticles, as components of their corona, compared to what is observed when they are transported freely from the extracellular medium.

  13. Effect of the protein corona on nanoparticles for modulating cytotoxicity and immunotoxicity

    Directory of Open Access Journals (Sweden)

    Lee YK

    2014-12-01

    Full Text Available Yeon Kyung Lee,1,* Eun-Ju Choi,2,* Thomas J Webster,3 Sang-Hyun Kim,4 Dongwoo Khang1 1Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, South Korea; 2Division of Sport Science, College of Science and Technology, Konkuk University, Chungju, South Korea; 3Department of Chemical Engineering and Program in Bioengineering, Northeastern University, Boston, MA, USA; 4Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, South Korea *These authors contributed equally to this work Abstract: Although the cytotoxicity of nanoparticles (NPs is greatly influenced by their interactions with blood proteins, toxic effects resulting from blood interactions are often ignored in the development and use of nanostructured biomaterials for in vivo applications. Protein coronas created during the initial reaction with NPs can determine the subsequent immunological cascade, and protein coronas formed on NPs can either stimulate or mitigate the immune response. Along these lines, the understanding of NP-protein corona formation in terms of physiochemical surface properties of the NPs and NP interactions with the immune system components in blood is an essential step for evaluating NP toxicity for in vivo therapeutics. This article reviews the most recent developments in NP-based protein coronas through the modification of NP surface properties and discusses the associated immune responses. Keywords: nanostructured biomaterials, blood response, cytotoxicity, immunotoxicity, protein corona

  14. Effect of the Protein Corona on Antibody-Antigen Binding in Nanoparticle Sandwich Immunoassays.

    Science.gov (United States)

    de Puig, Helena; Bosch, Irene; Carré-Camps, Marc; Hamad-Schifferli, Kimberly

    2017-01-18

    We investigated the effect of the protein corona on the function of nanoparticle (NP) antibody (Ab) conjugates in dipstick sandwich immunoassays. Ab specific for Zika virus nonstructural protein 1 (NS1) were conjugated to gold NPs, and another anti-NS1 Ab was immobilized onto the nitrocellulose membrane. Sandwich immunoassay formation was influenced by whether the strip was run in corona forming conditions, i.e., in human serum. Strips run in buffer or pure solutions of bovine serum albumin exhibited false positives, but those run in human serum did not. Serum pretreatment of the nitrocellulose also eliminated false positives. Corona formation around the NP-Ab in serum was faster than the immunoassay time scale. Langmuir binding analysis determined how the immobilized Ab affinity for the NP-Ab/NS1 was impacted by corona formation conditions, quantified as an effective dissociation constant, KD(eff). Results show that corona formation mediates the specificity and sensitivity of the antibody-antigen interaction of Zika biomarkers in immunoassays, and plays a critical but beneficial role.

  15. Driving extreme variability: The evolving corona and evidence for jet launching in Markarian 335

    CERN Document Server

    Wilkins, D R

    2015-01-01

    Variations in the X-ray emission from the narrow line Seyfert 1 galaxy, Markarian 335 (Mrk 335), are studied on both long and short timescales through observations made between 2006 and 2013 with XMM-Newton, Suzaku and NuSTAR. Changes in the geometry and energetics of the corona that give rise to this variability are inferred through measurements of the relativistically blurred reflection seen from the accretion disc. On long timescales, we find that during the high flux epochs the corona has expanded, covering the inner regions of the accretion disc out to a radius of 26(-7,+10)rg. The corona contracts to within 12rg and 5rg in the intermediate and low flux epochs, respectively. While the earlier high flux observation made in 2006 is consistent with a corona extending over the inner part of the accretion disc, a later high flux observation that year revealed that the X-ray source had become collimated into a vertically-extended jet-like corona and suggested relativistic motion of material upward. On short ti...

  16. Clusterin in the protein corona plays a key role in the stealth effect of nanoparticles against phagocytes.

    Science.gov (United States)

    Aoyama, Michihiko; Hata, Katsutomo; Higashisaka, Kazuma; Nagano, Kazuya; Yoshioka, Yasuo; Tsutsumi, Yasuo

    2016-10-28

    In biological fluids, nanoparticles interact with biological components such as proteins, and a layer called the "protein corona" forms around the nanoparticles. It is believed that the composition of the protein corona affects the cellular uptake and in vivo biodistribution of nanoparticles; however, the key proteins of the protein corona that control the biological fate of nanoparticles remain unclear. Recently, it was reported that clusterin binding to pegylated nanoparticles is important for the stealth effect of pegylated nanoparticles in phagocytes. However, the effect of clusterin on non-pegylated nanoparticles is unknown, although it is known that clusterin is present in the protein corona of non-pegylated nanoparticles. Here, we assessed the stealth effect of clusterin in the corona of non-pegylated silver nanoparticles and silica nanoparticles. We found that serum- and plasma-protein corona inhibited the cellular uptake of silver nanoparticles and silica nanoparticles in phagocytes and that the plasma-protein corona showed a greater stealth effect compared with the serum-protein corona. Clusterin was present in both the serum- and plasma-protein corona, but was present at a higher level in the plasma-protein corona than in the serum-protein corona. Clusterin binding to silver nanoparticles and silica nanoparticles suppressed the cellular uptake of nanoparticles in human macrophage-like cells (THP-1 cells). Although further studies are required to determine how clusterin suppresses non-specific cellular uptake in phagocytes, our data suggest that clusterin plays a key role in the stealth effect of not only pegylated nanoparticles but also non-pegylated nanoparticles.

  17. Broadband Spectroscopy of the Corona during the Total Solar Eclipse of March 29, 2006

    Science.gov (United States)

    Jaeggli, Sarah A.; Habbal, S. R.; Kuhn, J. R.; Nayfeh, M. H.

    2006-12-01

    We present coronal observations from the total solar eclipse of 29 March 2006 taken near Waw al Namus, Libya. During the 4 minutes and 6 seconds of totality, observations were made with a tracking collecting mirror and fiber-fed spectrograph. The spectrograph used is a high quantum efficiency commercial Ocean Optics QE65000 Spectrometer with a wavelength range of 350 to 1100 nm, and spectral resolution of about 0.75 nm. High quantum efficiency allowed for many short exposures of the inner (100 msec) and outer (10,000 msec) corona during the eclipse. Important spectral features, and the difference in color between the inner and outer corona are identified. Atmospheric contributions are discussed. Likely candidates for the nature of dust grains contributing to the F-corona measurements are also presented. These are compared with laboratory spectra of silicon nanoparticles.

  18. Application of Excitation Function to the Prediction of RI Level Caused by Corona Discharge

    Institute of Scientific and Technical Information of China (English)

    ZHU Lingyu; JI Shengchang; HUI Sisi; GUO Jun; LI Yansong; FU Chenzhao

    2012-01-01

    Radio interference (RI), as an aftereffect of corona discharge, is an important research topic in the field of electromagnetic compatibility, where excitation function is applied broadly to the prediction of RI level. This paper presents the theory of excitation function method used in the RI level prediction. Then, some practical problems related to this method are discussed. The propagation procedure of corona current is solved by the phase-modal transformation, and the impedance matrix of multi transmission lines is calculated by a double logarithmic approximate model of Carson's Ground-Return impedance. At the same time, in order to calculate the RI level when total line corona is assumed, an analytical formula is deduced for integral operation. Based on the above solutions, an algorithm is presented and applied to the prediction of RI level of a practical overhead transmission line. Comparison of prediction and measurement results indicates that the algorithm proposed in this paper is effective and feasible.

  19. Dynamic development of the protein corona on silica nanoparticles: composition and role in toxicity

    Science.gov (United States)

    Mortensen, Ninell P.; Hurst, Gregory B.; Wang, Wei; Foster, Carmen M.; Nallathamby, Prakash D.; Retterer, Scott T.

    2013-06-01

    The formation and composition of the protein corona on silica (SiO2) nanoparticles (NP) with different surface chemistries was evaluated over time. Native SiO2, amine (-NH2) and carboxy (-COO-) modified NP were examined following incubation in mammalian growth media containing fetal bovine serum (FBS) for 1, 4, 24 and 48 hours. The protein corona transition from its early dynamic state to the later more stable corona was evaluated using mass spectrometry. The NP diameter was 22.4 +/- 2.2 nm measured by scanning transmission electron microscopy (STEM). Changes in hydrodynamic diameter and agglomeration kinetics were studied using dynamic light scattering (DLS). The initial surface chemistry of the NP played an important role in the development and final composition of the protein corona, impacting agglomeration kinetics and NP toxicity. Particle toxicity, indicated by changes in membrane integrity and mitochondrial activity, was measured by lactate dehydrogenase (LDH) release and tetrazolium reduction (MTT), respectively, in mouse alveolar macrophages (RAW264.7) and mouse lung epithelial cells (C10). SiO2-COO- NP had a slower agglomeration rate, formed smaller aggregates, and exhibited lower cytotoxicity compared to SiO2 and SiO2-NH2. Composition of the protein corona for each of the three NP was unique, indicating a strong dependence of corona development on NP surface chemistry. This work underscores the need to understand all aspects of NP toxicity, particularly the influence of agglomeration on effective dose and particle size. Furthermore, the interplay between materials and local biological environment is emphasized and highlights the need to conduct toxicity profiling under physiologically relevant conditions that provide an appropriate estimation of material modifications that occur during exposure in natural environments.The formation and composition of the protein corona on silica (SiO2) nanoparticles (NP) with different surface chemistries was evaluated

  20. Surface-initiated graft polymerization on multiwalled carbon nanotubes pretreated by corona discharge at atmospheric pressure.

    Science.gov (United States)

    Xu, Lihua; Fang, Zhengping; Song, Ping'an; Peng, Mao

    2010-03-01

    Surface-initiated graft polymerization on multi-walled carbon nanotubes pretreated with a corona discharge at atmospheric pressure was explored. The mechanism of the corona-discharge-induced graft polymerization is discussed. The results indicate that MWCNTs were encapsulated by poly(glycidyl methacrylate) (PGMA), demonstrating the formation of PGMA-grafted MWCNTs (PGMA-g-MWCNTs), with a grafting ratio of about 22 wt%. The solubility of PGMA-g-MWCNTs in ethanol was dramatically improved compared to pristine MWCNTs, which could contribute to fabricating high-performance polymer/MWCNTs nanocomposites in the future. Compared with most plasma processes, which operate at low pressures, corona discharge has the merit of working at atmospheric pressure.

  1. Combined corona discharge and UV photoionization source for ion mobility spectrometry.

    Science.gov (United States)

    Bahrami, Hamed; Tabrizchi, Mahmoud

    2012-08-15

    An ion mobility spectrometer is described which is equipped with two non-radioactive ion sources, namely an atmospheric pressure photoionization and a corona discharge ionization source. The two sources cannot only run individually but are additionally capable of operating simultaneously. For photoionization, a UV lamp was mounted parallel to the axis of the ion mobility cell. The corona discharge electrode was mounted perpendicular to the UV radiation. The total ion current from the photoionization source was verified as a function of lamp current, sample flow rate, and drift field. Simultaneous operation of the two ionization sources was investigated by recording ion mobility spectra of selected samples. The design allows one to observe peaks from either the corona discharge or photoionization individually or simultaneously. This makes it possible to accurately compare peaks in the ion mobility spectra from each individual source. Finally, the instrument's capability for discriminating two peaks appearing in approximately identical drift times using each individual ionization source is demonstrated.

  2. Surface oxide formation during corona discharge treatment of AA 1050 aluminium surfaces

    DEFF Research Database (Denmark)

    Minzari, Daniel; Møller, Per; Kingshott, Peter

    2008-01-01

    Atmospheric plasmas have traditionally been used as a non-chemical etching process for polymers, but the characteristics of these plasmas could very well be exploited for metals for purposes more than surface cleaning that is presently employed. This paper focuses on how the corona discharge...... process modifies aluminium AA 1050 surface, the oxide growth and resulting corrosion properties. The corona treatment is carried out in atmospheric air. Treated surfaces are characterized using XPS, SEM/EDS, and FIB-FESEM and results suggest that an oxide layer is grown, consisting of mixture of oxide...... and hydroxide. The thickness of the oxide layer extends to 150–300 nm after prolonged treatment. Potentiodynamic polarization experiments show that the corona treatment reduces anodic reactivity of the surface significantly and a moderate reduction of the cathodic reactivity....

  3. Chandra Survey of Nearby Highly Inclined Disc Galaxies - III: Comparison with Hydrodynamical Simulations of Circumgalactic Coronae

    CERN Document Server

    Li, Jiang-Tao; Wang, Q Daniel

    2014-01-01

    X-ray observations of circumgalactic coronae provide a valuable means by which to test galaxy formation theories. Two primary mechanisms are thought to be responsible for the establishment of such coronae: accretion of intergalactic gas (IGM) and/or galactic feedback. In this paper, we first compare our Chandra sample of galactic coronae of 53 nearby highly-inclined disc galaxies to an analytical model considering only the accretion of IGM. We confirm the existing conclusion that this pure accretion model substantially over-predicts the coronal emission. We then select 30 field galaxies from our original sample, and correct their coronal luminosities to uniformly compare them to deep X-ray measurements of several massive disc galaxies from the literature, as well as to a comparable sample of simulated galaxies drawn from the Galaxies-Intergalactic Medium Interaction Calculation (GIMIC). These simulations explicitly model both accretion and SNe feedback and yield galaxies exhibit X-ray properties in broad agre...

  4. Heating of the Solar Corona by Alfven Waves: Self-Induced Opacity

    CERN Document Server

    Zahariev, N I

    2011-01-01

    There have been derived equations describing the static distributions of temperature and wind velocity at the transition region within the framework of the magnetohydrodynamics (MHD) of fully ionized hydrogen plasma . We have also calculated the width of the transition between the chromosphere and corona as a self-induced opacity of the high-frequency Alfven waves (AWs). The domain wall is a direct consequence of the self-consistent MHD treatment of AWs propagation. We predict considerable spectral density of the high-frequency AWs in the photosphere. The idea that Alfven waves might heat the solar corona belong to Alfven - we simply derived the corresponding MHD equations. The comparison of the solutions to those equations with the observational/measured data will be crucial for revealing the heating mechanism. The analysis of those solutions will explain how Alfven waves brick unto the corona and dissipate their energy there.

  5. Removal of NO and SO2 in Corona Discharge Plasma Reactor with Water Film

    Institute of Scientific and Technical Information of China (English)

    贺元吉; 董丽敏; 杨嘉祥

    2004-01-01

    In this paper, a novel type of a corona discharge plasma reactor was designed, which consists of needle-plate-combined electrodes, in which a series of needle electrodes are placed in a glass container filled with flue gas, and a plate electrode is immersed in the water. Based on this model, the removal of NO and SO2 was tested experimentally. In addition, the effect of streamer polarity on the reduction of SO2 and NO was investigated in detail. The experimental results show that the corona wind formed between the high-voltage needle electrode and the water by corona discharge enhances the cleaning efficiency of the flue gas because of the presence of water,and the cleaning efficiency will increase with the increase of applied dc voltage within a definite range. The removal efficiency of SO2 up to 98%, and about 85% of NOx removal under suitable conditions is obtained in our experiments.

  6. Controlling the Stealth Effect of Nanocarriers through Understanding the Protein Corona.

    Science.gov (United States)

    Schöttler, Susanne; Landfester, Katharina; Mailänder, Volker

    2016-07-25

    The past decade has seen a significant increase in interest in the use of polymeric nanocarriers in medical applications. In particular, when used as drug vectors in targeted delivery, nanocarriers could overcome many obstacles for drug therapy. Nevertheless, their application is still impeded by the complex composition of the blood proteins covering the particle surface, termed the protein corona. The protein corona complicates any prediction of cell interactions, biodistribution, and toxicity. In particular, the unspecific uptake of nanocarriers is a major obstacle in clinical studies. This Minireview provides an overview of what we currently know about the characteristics of the protein corona of nanocarriers, with a focus on surface functionalization that reduces unspecific uptake (the stealth effect). The ongoing improvement of nanocarriers to allow them to meet all the requirements necessary for successful application, including targeted delivery and stealth, are further discussed.

  7. The concept of bio-corona in modulating the toxicity of engineered nanomaterials (ENM).

    Science.gov (United States)

    Westmeier, Dana; Stauber, Roland H; Docter, Dominic

    2016-05-15

    Besides the wide use of engineered nanomaterials (ENM) in technical products, their application spectrum in biotechnology and biomedicine is steadily increasing. In complex physiological environments the physico-chemical properties and the behavior of nanoparticles (NPs) are challenging to characterize. Biomolecules rapidly adsorb to the nanomaterial, leading to the formation of the protein/biomolecule corona, which critically affects the nanomaterials' (patho)biological and technical identities. This formation can trigger an immune response and affect nanoparticles' toxicity and targeting capabilities. In this review, we provide a survey of recent findings on the (protein)corona-nanoparticle interaction and discuss how the corona modulates both cytotoxicity and the immune response as well as to improve the efficacy of targeted delivery of nanocarriers.

  8. The Role of Magnetic Helicity in the Structure and Heating of the Sun's Corona

    CERN Document Server

    Knizhnik, Kalman J

    2016-01-01

    Two of the most important features of the solar atmosphere are its hot, smooth coronal loops and the concentrations of magnetic shear, known as filament channels, that reside above photospheric polarity inversion lines (PILs). The shear observed in filament channels represents magnetic helicity, while the smoothness of the coronal loops indicates an apparent lack of magnetic helicity in the rest of the corona. At the same time, models that attempt to explain the high temperatures observed in these coronal loops require magnetic energy, in the form of twist, to be injected at the photosphere. In addition to magnetic energy, this twist also represents magnetic helicity. Unlike magnetic energy, magnetic helicity is conserved under reconnection, and is consequently expected to accumulate and be observed in the corona. However, filament channels, rather than the coronal loops, are the locations in the corona where magnetic helicity is observed, and it manifests itself in the form of shear, rather than twist. This ...

  9. Research on dual spectrum solar-blind ultraviolet corona detection system

    Science.gov (United States)

    Yang, Feng; Gu, Yan; Sun, Jianning; Pan, Jingsheng; Zhu, Bo; Wang, Qi; Lu, Xiaoqing

    2015-04-01

    A dual spectrum solar-blind ultraviolet (UV) corona detection system is designed in this paper. A common optical axis using a dichroic mirror is applied to this system in order to make visible light and ultraviolet light spectroscopy to ultraviolet detector and visible detectors. A high speed circuit of image processing based on TMS320DM642 DSP and a circuit that is used into system control and power management based on microcontroller are designed for the presented system. On the basis of the multi-threaded programming ideas, real-time image acquisition of ultraviolet and visible detectors, ultraviolet image noise reduction, image registration, dual spectral integration, Characteristic superimposing, serial communication and image display are achieved by using the DSP image processing circuit. Experimental results show that the dual spectrum solar-blind ultraviolet corona detection system has a good performance of corona detection based on ultraviolet and visible image fusion.

  10. Spectral Line Non-thermal Broadening and MHD Waves in the Solar Corona

    Science.gov (United States)

    Zaqarashvili, T. V.

    2009-04-01

    The rapid temperature rise from the solar surface (6000 K) up to the corona (1 MK) and acceleration of solar wind particles still are unresolved problems in solar physics. The energy source for the coronal heating and the wind acceleration probably lies in the solar photosphere. MHD waves are believed to carry the photospheric energy into the corona. Recent observations from space based telescopes made significant progress in understanding the process of MHD wave propagation from the solar surface towards the corona. Some of MHD wave modes have been observed through intensity variations and Doppler shift oscillations in spectral lines. Another powerful mechanism is to detect the waves through the non-thermal broadening of spectral lines. The lecture gives the basic points of wave induced effects in solar coronal spectral lines and recent progress in wave observations through spectral line non-thermal broadening.

  11. On Spectra Of Variants Of The Corona Of Two Graphs And Some New Equienergetic Graphs

    OpenAIRE

    Adiga Chandrashekar; Rakshith B.R.

    2016-01-01

    Let G and H be two graphs. The join G ∨ H is the graph obtained by joining every vertex of G with every vertex of H. The corona G ○ H is the graph obtained by taking one copy of G and |V (G)| copies of H and joining the i-th vertex of G to every vertex in the i-th copy of H. The neighborhood corona G★H is the graph obtained by taking one copy of G and |V (G)| copies of H and joining the neighbors of the i-th vertex of G to every vertex in the i-th copy of H. The edge corona G ◇ H is the graph...

  12. Towards a Realistic, Data-Driven Thermodynamic MHD Model of the Global Solar Corona

    CERN Document Server

    Downs, Cooper; van der Holst, Bart; Lugaz, Noé; Sokolov, Igor V; Gombosi, Tamas I

    2009-01-01

    In this work we describe our implementation of a thermodynamic energy equation into the global corona model of the Space Weather Modeling Framework (SWMF), and its development into the new Lower Corona (LC) model. This work includes the integration of the additional energy transport terms of coronal heating, electron heat conduction, and optically thin radiative cooling into the governing magnetohydrodynamic (MHD) energy equation. We examine two different boundary conditions using this model; one set in the upper transition region (the Radiative Energy Balance model), as well as a uniform chromospheric condition where the transition region can be modeled in its entirety. Via observation synthesis from model results and the subsequent comparison to full sun extreme ultraviolet (EUV) and soft X-Ray observations of Carrington Rotation (CR) 1913 centered on Aug 27, 1996, we demonstrate the need for these additional considerations when using global MHD models to describe the unique conditions in the low corona. Th...

  13. Nanosilver pathophysiology in earthworms: Transcriptional profiling of secretory proteins and the implication for the protein corona

    DEFF Research Database (Denmark)

    Hayashi, Yuya; Miclaus, Teodora; Engelmann, Péter;

    2016-01-01

    Previously we have identified lysenin as a key protein constituent of the secretome from Eisenia fetida coelomocytes and revealed its critical importance in priming interactions between the cells and the protein corona around nanosilver. As alterations of the protein environment can directly affect...... the corona composition, the extent to which nanoparticles influence the cells’ protein secretion profile is of remarkable interest that has rarely acquired attention. Here, we have probed transcriptional responses of E. fetida coelomocytes to the representative nanosilver NM-300K (15 nm) in a time...... suppressed over time indicating a negative feedback cycle. This may limit further enrichment of lysenin in the corona and thereby decrease the lysenin-assisted uptake of the nanoparticles. Other differentially expressed genes were those involved in metal stress (likewise in AgNO3-stressed cells) and in Toll...

  14. Disk-Corona Model in Active Galactic Nuclei:an Observational Test

    Institute of Scientific and Technical Information of China (English)

    Fang Yang; Chen Hu; Yan-Mei Chen; Jian-Min Wang

    2007-01-01

    We compiled a sample of 98 radio-quiet active galactic nuclei observed by ASCA,Chandra.XMM-Newton,INTEGRAL and Swift with the aim of testing the formation of hot corona and the magnetic shear stress operating in a disk-corona system.We found a strong correlation between the hard X-ray luminosity,bolometric luminosity LBol and Eddington luminosity LEdd.in the sense that the fraction f of hard X-ray to the bolometric luminosity is inversely proportional to the Eddington ratio.This correlation favors the shear stress tensor being of the form of trφ∝ Pgas,with which the disk-corona structure is stable.

  15. Coronae as Consequence of Large Scale Magnetic Fields in Turbulent Accretion Disks

    DEFF Research Database (Denmark)

    G. Blackman, Eric; Pessah, Martin Elias

    2009-01-01

    Non-thermal X-ray emission in compact accretion engines can be interpreted to result from magnetic dissipation in an optically thin magnetized corona above an optically thick accretion disk. If coronal magnetic field originates in the disk and the disk is turbulent, then only magnetic structures...... large enough for their turbulent shredding time to exceed their buoyant rise time survive the journey to the corona. We use this concept and a physical model to constrain the minimum fraction of magnetic energy above the critical scale for buoyancy as a function of the observed coronal to bolometric...... AGN, for which of order 30 per cent of the bolometric flux is in the X-ray band, we find that more than 20 per cent of the magnetic energy must be of large enough scale to rise and dissipate in the corona....

  16. A global galactic dynamo with a corona constrained by relative helicity

    CERN Document Server

    Prasad, A

    2015-01-01

    We present a model for a global axisymmetric turbulent dynamo operating in a galaxy with a corona which treats the supernovae (SNe) and magneto-rotational instability (MRI) driven turbulence parameters under a common formalism. The nonlinear quenching of the dynamo is alleviated by inclusion of small-scale advective and diffusive magnetic helicity fluxes, which allow the gauge invariant magnetic helicity to be transferred outside the disk and consequently build up a corona during the course of dynamo action. The time-dependent dynamo equations are expressed in a separable form and solved through an eigenvector expansion constructed using the steady-state solutions of the dynamo equation. The parametric evolution of the dynamo solution allows us to estimate the final structure of the global magnetic field and the saturated value of the turbulence parameter $\\alpha_m$, even before solving the dynamical equations for evolution of magnetic fields in the disk and the corona, along with $\\alpha$-quenching. We then ...

  17. On ion-cyclotron-resonance heating of the corona and solar wind

    Directory of Open Access Journals (Sweden)

    E. Marsch

    2003-01-01

    Full Text Available This paper concisely summarizes and critically reviews recent work by the authors on models of the heating of the solar corona by resonance of ions with high-frequency waves (up to the proton cyclotron frequency. The quasi-linear theory of pitch angle diffusion is presented in connection with relevant solar wind proton observations. Hybrid fluid-kinetic model equations, which include wave-particle interactions and collisions, are derived. Numerical solutions are discussed, representative of the inner corona and near-Sun solar wind. A semi-kinetic model for reduced velocity distributions is presented, yielding kinetic results for heavy ions in the solar corona. It is concluded that a self-consistent treatment of particle distributions and wave spectra is required, in order to adequately describe coronal physics and to obtain agreement with observations.

  18. Ultra-fine-scale filamentary structures in the Outer Corona and the Solar Magnetic Field

    Science.gov (United States)

    Woo, Richard

    2006-01-01

    Filamentary structures following magnetic field lines pervade the Sun's atmosphere and offer us insight into the solar magnetic field. Radio propagation measurements have shown that the smallest filamentary structures in the solar corona are more than 2 orders of magnitude finer than those seen in solar imaging. Here we use radio Doppler measurements to characterize their transverse density gradient and determine their finest scale in the outer corona at 20-30 R(circled dot operator), where open magnetic fields prevail. Filamentary structures overly active regions have the steepest gradient and finest scale, while those overlying coronal holes have the shallowest gradient and least finest scale. Their organization by the underlying corona implies that these subresolution structures extend radially from the entire Sun, confirming that they trace the coronal magnetic field responsible for the radial expansion of the solar wind. That they are rooted all over the Sun elucidates the association between the magnetic field of the photosphere and that of the corona, as revealed by the similarity between the power spectra of the photospheric field and the coronal density fluctuations. This association along with the persistence of filamentary structures far from the Sun demonstrate that subresolution magnetic fields must play an important role not only in magnetic coupling of the photosphere and corona, but also in coronal heating and solar wind acceleration through the process of small-scale magnetic reconnection. They also explain why current widely used theoretical models that extrapolate photospheric magnetic fields into the corona do not predict the correct source of the solar wind.

  19. Profundidad del surco gingival en dientes primarios restaurados con coronas de acero cromo

    Directory of Open Access Journals (Sweden)

    Rubén Muñoz Delgado

    2015-01-01

    Full Text Available Objetivo: Evaluar la relación entre el ajuste marginal y la profundidad del surco gingival en dientes primarios restaurados con coronas de acero cromo. Métodos: Se midió la profundidad del surco gingival de 114 dientes primarios restaurados con coronas de acero cromo en 67 niños, ambos sexos, de 3 a 6 años de edad de la clínica de Estomatología Pediátrica de la UATx, México. La población en estudio fue dividida en tres grupos: a experimental (n=30, b control (n=8, y c control negativo (n=29. Previo consentimiento informado se tomaron los índices de placa (LöeSilness 1967 e índice gingival en seis superficies; se midió el surco gingival con sonda periodontal y las coronas de acero cromo fueron evaluadas clínica y radiográficamente según su ajuste marginal y longitud cervical. Resultados: Los índices de placa y gingival no mostraron diferencias significativas para los grupos experimental y control negativo. El 34% de las coronas mostraron buen ajuste marginal, 33% un mal ajuste, 10.5% cortas, 7.9% largas y el 14% otro tipo de mal ajuste. La profundidad del surco gingival fue estadísticamente significativa para el primer y segundo molar inferior derechos y en los caninos inferiores (p >0.05; la superficie disto-vestibular presentó la mayor profundidad del surco gingival (2.34 mm, siendo estadísticamente significativa (p>0.05. Conclusiones: La profundidad del surco gingival fue mayor en los dientes rehabilitados con coronas de acero cromo mal ajustadas y sobre contorneadas (largas. La presencia de placa bacteriana y gingivitis estuvo relacionada con las coronas de acero cromo mal ajustadas.

  20. Laboratory Identification of MHD Eruption Criteria in the Solar Corona

    Science.gov (United States)

    Yamada, M.; Myers, C. E.; Ji, H.; Yoo, J.; Fox, W. R., II; Jara-Almonte, J.; Savcheva, A. S.; DeLuca, E. E.

    2015-12-01

    Ideal magnetohydrodynamic (MHD) instabilities such as the kink [1] and torus [2] instabilities are believed to play an important role in driving "storage-and-release" eruptions in the solar corona. These instabilities act on long-lived, arched magnetic flux ropes that are "line-tied" to the solar surface. In spite of numerous observational and computational studies, the conditions under which these instabilities produce an eruption remain a subject of intense debate. In this paper, we use a line-tied, arched flux rope experiment to study storage-and-release eruptions in the laboratory [3]. An in situ array of miniature magnetic probes is used to assess the equilibrium and stability of the laboratory flux ropes. Two major results are reported here: First, a new stability regime is identified where torus-unstable flux ropes fail to erupt. In this "failed torus" regime, the flux rope is torus-unstable but kink-stable. Under these conditions, a dynamic "toroidal field tension force" surges in magnitude and causes the flux rope to contract. This tension force, which is missing from existing eruption models, is the J×B force between self-generated poloidal currents in the flux rope and the toroidal (guide) component of the vacuum field. Secondly, a clear torus instability threshold is observed in the kink-unstable regime. This latter result, which is consistent with existing theoretical [4] and numerical [5] findings, verifies the key role of the torus instability in driving some solar eruptions. This research is supported by DoE Contract No. DE-AC02-09CH11466 and by the NSF/DoE Center for Magnetic Self-Organization (CMSO). [1] Hood & Priest, Geophys. Astrophys. Fluid Dynamics 17, 297 (1981) [2] Kliem & Török, Phys. Rev. Lett. 96, 255002 (2006) [3] Myers, Ph.D. Thesis, Princeton University (2015) [4] Olmedo & Zhang, Astrophys. J. 718, 433 (2010) [5] Török & Kliem, Astrophys. J. 630, L97 (2005)