Science.gov

Sample records for astronautas del gemini

  1. Gemini

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Rear view of rendezvous docking simulator. Francis B. Smith wrote: 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.'

  2. Gemini

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Gemini Rendezvous Docking Simulator suspended from the roof of the Langley Research Center's aircraft hanger closing in on its Agena target. Francis B. Smith wrote in his paper 'Simulators for Manned Space Research,' 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.' This is a photograph of 'the Gemini spacecraft approaching the Agena target in a final docking maneuver.'

  3. Gemini

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Multiple exposure of Gemini rendezvous docking simulator. Francis B. Smith wrote in his paper 'Simulators for Manned Space Research,' 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.' A.W. Vogeley further described the simulator in his paper 'Discussion of Existing and Planned Simulators For Space Research,' 'Docking operations are considered to start when the pilot first can discern vehicle target size and aspect and terminate, of course, when soft contact is made. ... This facility enables simulation of the docking operation from a distance of 200 feet to actual contact with the target. A full-scale mock-up of the target vehicle is suspended near one end of the track. ... On [the Agena target] we have mounted the actual Agena docking mechanism and also various types of visual aids. We have been able to devise visual aids which have made it possible to accomplish nighttime docking with as much success as daytime docking.'

  4. Formación estelar en NGC 6357: viendo a través del polvo con Gemini

    NASA Astrophysics Data System (ADS)

    Bosch, G.; Morrell, N.; Barbá, R.

    Presentamos aquí los primeros resultados de fotometría JHKs obtenidos con Flamingos I en el telescopio Gemini Sur. El mosaico comprendido por tres posiciones adyacentes tomadas a lo largo de varios semestres nos permite caracterizar la población estelar en la zona que presenta una interacción más importante entre las estrellas masivas y la nube molecular que les dió origen. Los diagramas color-magnitud nos permiten identificar numerosas fuentes con exceso infrarrojo, la mayoría de ellas imposible de detectarse en el rango óptico debido a la fuerte absorción del polvo presente en la región. Es altamente probable que la mayoría de estas fuentes con exceso sean protoestrellas, aunque es necesario realizar espectroscopía infrarroja de las mismas para confirmar su naturaleza.

  5. Gemini Space Program emblem

    NASA Technical Reports Server (NTRS)

    1965-01-01

    The insignia of the Gemini space program is a disc of dark blue as a background for a gold Zodiac Gemini symbol. A white star on each of the two vertical curves of the Gemini symbol represent the Gemini twins, Pollux and Castor.

  6. Gemini Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Gemini Rendezvous Docking Simulator suspended from the roof of the Langley Research Center's aircraft hanger. Francis B. Smith wrote: 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.'

  7. Instrumentation at Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Kleinman, S. J.; Boccas, Maxime; Goodsell, Stephen J.; Gomez, Percy; Murowinski, Rick; Chené, André-Nicolas; Henderson, David

    2014-07-01

    Gemini South's instrument suite has been completely transformed since our last biennial update. We commissioned the Gemini Multi-Conjugate Adaptive Optics System (GeMS) and its associated Gemini South Adaptive Optics Imager (GSAOI) as well as Flamingos-2, our long-slit and multi-object infrared imager and spectrograph, and the Gemini Planet Imager (GPI). We upgraded the CCDs in GMOS-S, our multi-object optical imager and spectrograph, with the GMOS-N CCD upgrade scheduled for 2015. Our next instrument, the Gemini High-resolution Optical SpecTrograph (GHOST) is in its preliminary design stage and we are making plans for the instrument to follow:Gen4#3.

  8. Gemini IRAF: Data reduction software for the Gemini telescopes

    NASA Astrophysics Data System (ADS)

    Gemini Observatory; AURA

    2016-08-01

    The Gemini IRAF package processes observational data obtained with the Gemini telescopes. It is an external package layered upon IRAF and supports data from numerous instruments, including FLAMINGOS-2, GMOS-N, GMOS-S, GNIRS, GSAOI, NIFS, and NIRI. The Gemini IRAF package is organized into sub-packages; it contains a generic tools package, "gemtools", along with instrument-specific packages. The raw data from the Gemini facility instruments are stored as Multi-Extension FITS (MEF) files. Therefore, all the tasks in the Gemini IRAF package, intended for processing data from the Gemini facility instruments, are capable of handling MEF files.

  9. Recent advances in gemini surfactants: oleic Acid-based gemini surfactants and polymerizable gemini surfactants.

    PubMed

    Sakai, Kenichi; Sakai, Hideki; Abe, Masahiko

    2011-01-01

    Gemini surfactants recently developed by our research group are introduced from the standpoints of their syntheses, aqueous solution properties, and potential applications. Two series of gemini surfactants are introduced in this short review, the first of which is the oleic acid-based gemini surfactants, and the second is the polymerizable gemini surfactants. These gemini surfactants have been developed not only as environmentally friendly materials (the use of gemini surfactants enables the reduction of the total consumption of surfactants in chemical products owing to their excellent adsorption and micellization capabilities at low concentrations) but also as functional organic materials.

  10. Gemini telescope structure design

    NASA Astrophysics Data System (ADS)

    Raybould, Keith; Gillett, Paul E.; Hatton, Peter; Pentland, Gordon; Sheehan, Mike; Warner, Mark

    1994-06-01

    The Gemini project is an international collaboration to design, fabricate, and assemble two 8 M telescopes, one on Mauna Kea in Hawaii, the other on Cerro Pachon in Chile. The telescopes will be national facilities designed to meet the Gemini Science Requirements (GSR), a document developed by the Gemini Science Committee (GSC) and the national project scientists. The Gemini telescope group, based on Tucson, has developed a telescope structure to meet the GSR. This paper describes the science requirements that have technically driven the design, and the features that have been incorporated to meet these requirements. This is followed by a brief description of the telescope design. Finally, analyses that have been performed and development programs that have been undertaken are described briefly. Only the designs that have been performed by the Gemini Telescope Structure, Building and Enclosure Group are presented here; control, optical systems, acquisition and guiding, active and adaptive optics, Cassegrain rotator and instrumentation issues are designed and managed by others and will not be discussed here, except for a brief description of the telescope configurations to aid subsequent discussions.

  11. Gemini Instrument Upgrade Program

    NASA Astrophysics Data System (ADS)

    Diaz, Ruben; Goodsell, Stephen; Kleinman, Scot

    2016-08-01

    The Gemini Observatory* remains committed to keeping its operational instrumentation competitive and serving the needs of its user community. Currently the observatory operates a 4 instruments + 1 AO system at each site. At Gemini North the GMOS-N, GNIRS, NIFS and NIRI instruments are offered supported by the ALTAIR AO system. In the south, GMOS-S, F-2, GPI and GSAOI are offered instrumentation and GeMS is the provided AO System. This paper reviews our strategy to keep our instrumentation suite competitive, examines both our current funded upgrade projects and our potential future enhancements. We summarize the work done and the results so far obtained within the instrument upgrade program.

  12. Gemini Scout Control Software

    SciTech Connect

    Clinton Hobart, Justin Garretson

    2010-11-23

    The Gemini Scout Control Software consists of two Windows applications that allow the Gemini Scout vehicle to be controlled by an operator. The Embedded application runs on the vehicle's Gemini Scout Control Software onboard computer and controls the vehicle's various motors and sensors. This application reports the vehicle's status and receives vehicle commands overthe local-area-network. The Embedded applicationalso allows the user to control the vehicle using a USB game-pad connected directly to the vehicle. The Operator Control Unit (OCU) application runs on an external PC and communicates with the vehicle via an Ethernet connection. The OCU application sends commands to and receives data from the Embedded application running on the vehicle. The OCU application also communicates directly with the digital video encoders and radios in order to display video from the vehicle's cameras and the status of the radio link. The OCU application has a graphical user interface (GUI) that displays the vehicle's status and allows the user to change various vehicle settings. Finally, the OCU application receives input from a USB game-pad connected to the PC in order to control the vehicle's functions.

  13. The Gemini Planet Imager

    SciTech Connect

    Macintosh, B; al., e

    2006-05-02

    The next major frontier in the study of extrasolar planets is direct imaging detection of the planets themselves. With high-order adaptive optics, careful system design, and advanced coronagraphy, it is possible for an AO system on a 8-m class telescope to achieve contrast levels of 10{sup -7} to 10{sup -8}, sufficient to detect warm self-luminous Jovian planets in the solar neighborhood. Such direct detection is sensitive to planets inaccessible to current radial-velocity surveys and allows spectral characterization of the planets, shedding light on planet formation and the structure of other solar systems. We have begun the construction of such a system for the Gemini Observatory. Dubbed the Gemini Planet Imager (GPI), this instrument should be deployed in 2010 on the Gemini South telescope. It combines a 2000-actuator MEMS-based AO system, an apodized-pupil Lyot coronagraph, a precision infrared interferometer for real-time wavefront calibration at the nanometer level, and a infrared integral field spectrograph for detection and characterization of the target planets. GPI will be able to achieve Strehl ratios > 0.9 at 1.65 microns and to observe a broad sample of science targets with I band magnitudes less than 8. In addition to planet detection, GPI will also be capable of polarimetric imaging of circumstellar dust disks, studies of evolved stars, and high-Strehl imaging spectroscopy of bright targets. We present here an overview of the GPI instrument design, an error budget highlighting key technological challenges, and models of the system performance.

  14. Project Gemini online digital archive

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-01-01

    An archive containing the first high-resolution digital scans of the original flight films from Project Gemini, the second U.S. human spaceflight program, was unveiled by the NASA Johnson Space Center and Arizona State University's (ASU) School of Earth and Space Exploration on 6 January. The archive includes images from 10 flights. Project Gemini, which ran from 1964 to 1966, followed Project Mercury and preceded the Apollo spacecraft. Mercury and Apollo imagery are also available through ASU. For more information, see http://tothemoon.ser.asu.edu/gallery/gemini and http://apollo.sese.asu.edu/index.html.

  15. Janus and Gemini Nanoplates

    NASA Astrophysics Data System (ADS)

    Cheng, Zhengdong; Mejia, Andres; Chang, Ya-Wen; He, Peng; Diaz, Agustin; Clearfield, Abraham

    2011-03-01

    Janus particles were used to make stable Pickering emulsions (emulsions stabilized by particles). Here we demonstrated a novel method to produce high aspect ratio Janus plates with atomic thickness. Gemini plates with only the edges functionalized are also fabricated. These novel nanoplates are observed to have super surface activity. Most importantly, these particles overcome the two opposite effects in the stabilization of Pickering emulsions using spherical particles: stabilization requires particles as small as possible; but smaller particles are easy to escape the interface due to Brownian motion since the adsorption energy to the oil-water interface is proportional to the diameter of the spheres. Our nanoplates have a large aspect ratio due to the extremely thin thickness, which offers extraordinary stability to the liquid film between two emulsions to prevent coalescence. In the meantime, their large lateral surface area offers strong adsorption energy at the oil-water interface.

  16. Gemini 9 spacecraft recovery operations

    NASA Technical Reports Server (NTRS)

    1966-01-01

    The Gemini 9-A spacecraft, with Astronauts Thomas Stafford and Eugene Cernan still inside, in water as the aircraft carrier U.S.S. Wasp, the recovery ship, comes alongside to recover the astronauts and their spaceship.

  17. The Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Graham, James R.; Macintosh, Bruce; Perrin, Marshall D.; Ingraham, Patrick; Konopacky, Quinn M.; Marois, Christian; Poyneer, Lisa; Bauman, Brian; Barman, Travis; Burrows, Adam Seth; Cardwell, Andrew; Chilcote, Jeffrey K.; De Rosa, Robert John J.; Dillon, Daren; Doyon, Rene; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Gavel, Donald; Goodsell, Stephen J.; Hartung, Markus; Hibon, Pascale; Kalas, Paul; Larkin, James E.; Maire, Jerome; Marchis, Franck; Marley, Mark S.; McBride, James; Millar-Blanchaer, Max; Morzinski, Kathleen M.; Nielsen, Eric L.; Norton, Andew; Oppenheimer, Rebecca; Palmer, David; Patience, Jenny; Pueyo, Laurent; Rantakyro, Fredrik; Sadakuni, Naru; Saddlemeyer, Leslie; Savransky, Dmitry; Serio, Andrew W.; Soummer, Remi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wang, Jason; Wiktorowicz, Sloane; Wolff, Schulyer; Gpi/Gpies Team

    2015-01-01

    The Gemini Planet Imager (GPI) is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of GPI has been tuned for maximum sensitivity to faint planets near bright stars. GPI has undergone a year of commissioning, verification, and calibration work. We have achieved an estimated H-band contrast (5-sigma) of 106 at 0.75 arcseconds and 105 at 0.35 arcseconds in spectral mode, and suppression of unpolarized starlight by a factor of 800 in imaging polarimetry mode. Early science observations include study of the spectra of β Pic b and HR 8799, orbital investigations of β Pic b and PZ Tel, and observations of the debris disk systems associated with β Pic, AU Mic, and HR 4796A. An 890-hour exoplanet survey with GPI is scheduled to begin in late 2014. A status report for the campaign will be presented.

  18. Index maps for Gemini earth photography

    NASA Technical Reports Server (NTRS)

    Giddings, L. E.

    1975-01-01

    Index maps for the Gemini missions are presented; these are for the Gemini 3 through Gemini 12 missions. The maps are divided into four sections: the whole earth; the Western Hemisphere and eastern Pacific Ocean; Africa, India, and the Near East; and Asia, Australia, and the Pacific Ocean.

  19. Recovery of Gemini 4 spacecraft and astronauts

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Recovery of Gemini 4 spacecraft and astronauts. Views include Astronaut James A. McDivitt, command pilot of the Gemini 4 space flight, sitting in life raft awaiting pickup by helicopter from the recovery ship, the aircraft carrier U.S.S. Wasp (33490); Navy frogmen stand on the flotation collar of the Gemini 4 spacecraft during recovery operations (33491).

  20. Structure-function study of gemini derivatives with two different side chains at C-20, Gemini-0072 and Gemini-0097.

    PubMed

    Huet, Tiphaine; Maehr, Hubert; Lee, Hong Jin; Uskokovic, Milan R; Suh, Nanjoo; Moras, Dino; Rochel, Natacha

    2011-01-01

    Derivatives of vitamin D(3) containing a second side-chain emanating at C-20 are known as gemini and act as vitamin D receptor agonists. Recently, two of these, namely Gemini-0072 and the epimeric Gemini-0097, were selected for further studies in view of their high biological activities and lack of hypercalcemic effects. We now show that the two analogs recruit coactivator SRC-1 better than the parental gemini and act as VDR superagonists. The crystal structures of complexes of zVDR with Gemini-0072 and Gemini-0097 indicate that these ligands induce an extra cavity within the ligand-binding pocket similar to gemini and that their superagonistic activity is due to an increased stabilization of helix H12.

  1. The Actual Gemini 9 Prime Crew

    NASA Technical Reports Server (NTRS)

    1966-01-01

    The Gemini 9 backup crew members are, Commander, Thomas P. Stafford and pilot Eugene A. Cernan. The back-up crew became the prime crew when on February 28, 1966 the prime crew for the Gemini 9 mission were killed when their twin seat T- 38 trainer jet aircraft crashed into a building during a landing approach in bad weather.

  2. Gemini

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    (the Twins; abbrev. Gem, gen. Geminorum; area 514 sq. deg.) A northern zodiacal constellation which lies between Auriga and Canis Minor, and culminates at midnight in early January. It represents Castor and Pollux, the twin sons of Leda, Queen of Sparta, in Greek mythology, whose brotherly love was rewarded by a place among the stars. Its brightest stars were cataloged by Ptolemy (c. AD 100-175) ...

  3. Gemini Observatory Multi-continental Network

    NASA Astrophysics Data System (ADS)

    Kennedy, James R.

    2002-11-01

    The Gemini Observatory operates two 8-meter IR/optical telescopes: one in Hawaii and the other in Chile. High-speed network connections among all of the mountain telescopes, their sea-level bases, and a support facility in Tucson are essential to their operation, providing video and audio communications, administrative computing systems, remote telescope operation, scientific data management, and many other applications. All the sites have recently been connected via the Abilene network, through collaborations with more than a dozen astronomy facilities near of the various Gemini sites, with Florida International University's AMPATH program, with various providers, and with grant support for the National Science Foundation. While the bandwidth levels required will change over time, Gemini's current objective is a minimum 10 Mbps presence on Internet2 to and from its principal sites. The Gemini North, Gemini South, and Tucson sites are at this level or better. Gemini North has been upgraded to a burst capability up to 155 Mbps to the US Mainland Internet2. Gemini South has burst capability to 10 Mbps, with 6 Mbps guarantied to the US Mainland Internet2.

  4. Gemini surfactants from natural amino acids.

    PubMed

    Pérez, Lourdes; Pinazo, Aurora; Pons, Ramon; Infante, Mrosa

    2014-03-01

    In this review, we report the most important contributions in the structure, synthesis, physicochemical (surface adsorption, aggregation and phase behaviour) and biological properties (toxicity, antimicrobial activity and biodegradation) of Gemini natural amino acid-based surfactants, and some potential applications, with an emphasis on the use of these surfactants as non-viral delivery system agents. Gemini surfactants derived from basic (Arg, Lys), neutral (Ser, Ala, Sar), acid (Asp) and sulphur containing amino acids (Cys) as polar head groups, and Geminis with amino acids/peptides in the spacer chain are reviewed.

  5. Fellow astronauts join Gemini 7 crew for preflight breakfast

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Fellow astronauts join the Gemini 7 prime crew for breakfeast in the Manned Spacecraft Operations Building, Merritt Island, on the day of the Gemini 7 launch. Clockwise around table, starting lower left, are Astronauts James A. Lovell Jr., Gemini 7 prime crew pilot; Walter M. Schirra Jr., Donald K. Slayton, MSC Assistant Director for Flight Crew Operations; Richard F. Gordon Jr., Gemini 8 backup crew pilot; Virgil I. Grissom, Charles Conrad Jr., and Frank Borman, Gemini 7 prime crew command pilot.

  6. Schirra, Stafford and Gemini on Deck

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronaut Walter H. Schirra Jr. (on right), Command pilot, climbs from his Gemini VI spacecraft as he and Astronaut Thomas P. Stafford (not in view) arrive aboard the aircraft carrier U.S.S. Wasp. They are assisted by various McDonell Douglas technicians. The Gemini VI spacecraft splashed down in the western Atlantic recover area at 10:29 a.m. (EST) December 16, 1965, after a successful 25 hr. 52 minute mission in space.

  7. Women Astronomers at Gemini: A Success Story

    NASA Astrophysics Data System (ADS)

    Rodgers, Bernadette; Jorgensen, I.; Barker, N.; Edwards, M.; Trancho, G.

    2010-01-01

    Gemini Observatory has been very successful at attracting, hiring and retaining female Scientists. We present data on the growth of the scientific staff since the start of the Observatory, and science fellow recruiting from 2006-2008. At Gemini 31% of the Science Staff holding PhDs are female compared with 13.9% within the United States. The Science Management is 75% female, as is 50% of the Gemini Directorate. This critical mass of female representation within the science staff and management appears to have had a positive effect on female recruitment and hiring. The science fellow recruitment during the past 3 years has attracted 21-38% female applicants and 57% of new hires during this period have been female scientists. Perhaps even more significant, the retention rate of female science staff at Gemini is 88%, compared to 64% for male science staff. There are likely many factors that contribute to this success, but the conclusion is that Gemini has earned a reputation in the scientific community as a place where female scientists are valued and can be successful.

  8. Antifungal activity of gemini quaternary ammonium salts.

    PubMed

    Obłąk, Ewa; Piecuch, Agata; Krasowska, Anna; Luczyński, Jacek

    2013-12-14

    A series of gemini quaternary ammonium chlorides and bromides with various alkyl chain and spacer lengths was synthesized. The most active compounds against fungi were chlorides with 10 carbon atoms within the hydrophobic chain. Among these compounds were few with no hemolytic activity at minimal inhibitory concentrations. None of the tested compounds were cytotoxic and mutagenic. Cationic gemini surfactants poorly reduced the adhesion of microorganisms to the polystyrene plate, but inhibited the filamentation of Candida albicans. One of the tested compounds eradicated C. albicans and Rodotorula mucilaginosa biofilm, what could be important in overcoming catheter-associated infections. It was also shown that gemini surfactants enhanced the sensitivity of C. albicans to azoles and polyenes, thus they might be potentially used in combined therapy against fungi.

  9. Summary analysis of the Gemini entry aerodynamics

    NASA Technical Reports Server (NTRS)

    Whitnah, A. M.; Howes, D. B.

    1972-01-01

    The aerodynamic data that were derived in 1967 from the analysis of flight-generated data for the Gemini entry module are presented. These data represent the aerodynamic characteristics exhibited by the vehicle during the entry portion of Gemini 2, 3, 5, 8, 10, 11, and 12 missions. For the Gemini, 5, 8, 10, 11, and 12 missions, the flight-generated lift-to-drag ratios and corresponding angles of attack are compared with the wind tunnel data. These comparisons show that the flight generated lift-to-drag ratios are consistently lower than were anticipated from the tunnel data. Numerous data uncertainties are cited that provide an insight into the problems that are related to an analysis of flight data developed from instrumentation systems, the primary functions of which are other than the evaluation of flight aerodynamic performance.

  10. The Original Gemini 9 Prime Crew

    NASA Technical Reports Server (NTRS)

    1966-01-01

    The original Gemini 9 prime crew, astronauts Elliot M. See Jr. (left), command pilot, and Charles A. Bassett II, pilot, in space suits with their helmets on the table in front of them. On February 28, 1966 the prime crew for the Gemini 9 mission were killed when their twin seat T-38 trainer jet aircraft crashed into a building in which the Gemini spacecraft were being manufactured. They were on final approach to Lambert-Saint Louis Municipal Airport when bad weather conditions hampered pilot See's ability to make a good visual contact with the runway. Noticing the building at the last second as he came out of the low cloud cover, See went to full afterburner and attempted to nose-up the aircraft in an attempt to miss the building. He clipped it and his plane crashed.

  11. Innovation without Boundaries: The Gemini. Assistive Technology. Associate Editor's Column.

    ERIC Educational Resources Information Center

    Ashton, Tamarah M.

    2001-01-01

    This article describes Gemini, an augmentative and alternative communication device that is also a full-featured Macintosh computer. The Gemini is designed to help individuals of all ages with learning, communication, or computer access difficulties to lead more independent lives. The benefits of Gemini are highlighted, including its weight of…

  12. Radiation dosimetry for the Gemini program

    NASA Technical Reports Server (NTRS)

    Richmond, R. G.

    1972-01-01

    The principal source of radiation for low-earth-orbit, low inclination space flights is in the area of the South Atlantic magnetic anomaly. None of the Gemini dose measurements reported in the paper are of high enough intensity to be considered hazardous. There is a trend toward larger doses as missions are flown higher and longer. Extended orbital operations between 1400 and 4400 kilometers would encounter high interior radiation levels. Pronounced spacecraft geometry effects have been measured in manned spacecraft. Instrumentation for radiation measurements on Gemini spacecraft is described.

  13. Adsorption of Gemini surfactants onto clathrate hydrates.

    PubMed

    Salako, O; Lo, C; Couzis, A; Somasundaran, P; Lee, J W

    2013-12-15

    This work addresses the adsorption of two Gemini surfactants at the cyclopentane (CP) hydrate-water interface. The Gemini surfactants investigated here are Dowfax C6L and Dowfax 2A1 that have two anionic head groups and one hydrophobic tail group. The adsorption of these surfactants was quantified using adsorption isotherms and the adsorption isotherms were determined using liquid-liquid titrations. Even if the Gemini surfactant adsorption isotherms show multi-layer adsorption, they possess the first Langmuir layer with the second adsorption layer only evident in the 2A1 adsorption isotherm. Zeta potentials of CP hydrate particles in the surfactant solution of various concentrations of Dowfax C6L and Dowfax 2A1 were measured to further explain their adsorption behavior at the CP hydrate-water interface. Zeta potentials of alumina particles as a model particle system in different concentrations of sodium dodecyl sulfate (SDS), Dowfax C6L and Dowfax 2A1 were also measured to confirm the configuration of all the surfactants at the interface. The determination of the isotherms and zeta-potentials provides an understanding framework for the adsorption behavior of the two Gemini surfactants at the hydrate-water interface.

  14. Geo-Engineering through Internet Informatics (GEMINI)

    SciTech Connect

    Doveton, John H.; Watney, W. Lynn

    2003-03-06

    The program, for development and methodologies, was a 3-year interdisciplinary effort to develop an interactive, integrated Internet Website named GEMINI (Geo-Engineering Modeling through Internet Informatics) that would build real-time geo-engineering reservoir models for the Internet using the latest technology in Web applications.

  15. The Gemini online data processing system

    NASA Astrophysics Data System (ADS)

    Walker, Shane; Gillies, Kim; Brighton, Allan

    2004-09-01

    Processing astronomical images is an inherently resource intensive procedure that is typically time consuming as well. At the same time, first order reductions are particularly important during the observing process since they can provide key quality assessment information. To resolve this conflict, the Online Data Processing (OLDP) system being commissioned at the Gemini Observatory automatically maps reduction sequences onto a cluster of servers during observing, taking advantage of available concurrency where possible. The user constructs a visual representation of the sequence for an observation using the Gemini Observing Tool. No constraints are placed upon the series of steps that comprise the sequence. At runtime, the OLDP reads the reduction sequence from the Observing Database and splits it into smaller pieces for simultaneous execution on the cluster. Recipe steps can be implemented in IRAF, shell scripts, or Java, and other types can be plugged into the architecture without modifying the core of the code base. This paper will introduce the Gemini OLDP and demonstrate how it utilizes modern infrastructure technology like Jini and JavaSpaces to achieve its goals.

  16. Gemini 10 prime crew during post flight press conference

    NASA Technical Reports Server (NTRS)

    1966-01-01

    At podium during Gemini 10 press conference are (l-r) Dr. Robert C. Seamans, Astronauts John Young and Michael Collins and Dr. Robert R. Gilruth (39895); Wide angle view of the Manned Spacecraft Center (MSC) News Center during the Gemini 10 prime crew post flight press conference (38786); Astronaut Young draws diagram on chalk board of tethered extravehicular activity accomplished during Gemini 10 flight (39897).

  17. The Transformation of Observatory Newsletters - A Gemini Perspective

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyu

    2015-08-01

    Astronomical observatories publish newsletters to communicate the observatory’s new discoveries and activities with its user communities, funding agencies, and general public. Gemini Observatory started publishing the newsletter in March 1992. Over the years, it transformed from a no-frills black and white publication to a full-color magazine type newsletter with a special name “GeminiFocus”. Since 2012, the contents of GeminiFocus moved from print to digital with an additional print issue of the Year in Review. The newsletter transformation is in sync with the rapid development of the internet technologies. We discuss here the evolvement of Gemini newsletter and the lessons learned.

  18. Experimentos submarinos

    NASA Video Gallery

    NEEMO se lleva a cabo en un laboratorio submarino llamado Aquarius. De la mano del astronauta de la NASA José Hernández conoce alguno de los experimentos que los astronautas (o acuanautas) hacen mi...

  19. Gemini-IFU Spectroscopy of HH 111

    NASA Astrophysics Data System (ADS)

    Cerqueira, A. H.; Vasconcelos, M. J.; Raga, A. C.; Feitosa, J.; Plana, H.

    2015-03-01

    We present new optical observations of the Herbig-Haro (HH) 111 jet using the Gemini Multi Object Spectrograph in its Integral Field Unit mode. Eight fields of 5\\prime\\prime × 3\\buildrel{\\prime\\prime}\\over{.} 5 have been positioned along and across the HH 111 jet, covering the spatial region from knot E to L in HH 111 (namely, knots E, F, G, H, J, K, and L). We present images and velocity channel maps for the [O i] 6300+6360, Hα, [N ii] 6548+6583, and [S ii] 6716+6730 lines, as well as for the [S ii] 6716/6730 line ratio. We find that the HH 111 jet has an inner region with lower excitation and higher radial velocity, surrounded by a broader region of higher excitation and lower radial velocity. Also, we find higher electron densities at lower radial velocities. These results imply that the HH 111 jet has a fast, axial region with lower velocity shocks surrounded by a lower velocity sheath with higher velocity shocks. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  20. Ultraviolet spectrophotometry of Sirius from Gemini 12

    NASA Technical Reports Server (NTRS)

    Spear, G. G.; Kondo, Y.; Henize, K. G.

    1974-01-01

    The spectral energy distribution of Sirius between 2500 and 3700 A at a resolution of 7 A is obtained from plates taken on Gemini 12. The agreement with other observations and the most recent line-blanketed model atmospheres is good. The equivalent width of the Mg II doublet near 2800 A is 6.0 A, if the continuum level is represented by regions near 2650 and 2910 A. This is consistent with expectations for a hot Am star and implies line blocking of up to 15% in this wavelength region.

  1. Solution properties and electrospinning of phosphonium gemini surfactants.

    PubMed

    Hemp, Sean T; Hudson, Amanda G; Allen, Michael H; Pole, Sandeep S; Moore, Robert B; Long, Timothy E

    2014-06-14

    Bis(diphenylphosphino)alkanes quantitatively react with excess 1-bromododecane to prepare novel phosphonium gemini surfactants with spacer lengths ranging from 2 to 4 methylenes (12-2/3/4-12P). Dodecyltriphenylphosphonium bromide (DTPP), a monomeric surfactant analog, was readily water soluble, however, in sharp contrast, phosphonium gemini surfactants were poorly soluble in water due to two hydrophobic tails and relatively hydrophobic cationic head groups containing phenyl substituents. Isothermal titration calorimetry did not reveal a measurable critical micelle concentration for the 12-2-12P phosphonium gemini surfactant in water at 25 °C. Subsequent studies in 50/50 v/v water-methanol at 25 °C showed a CMC of 1.0 mM for 12-2-12P. All phosphonium gemini surfactants effectively complexed nucleic acids, but failed to deliver nucleic acids in vitro to HeLa cells. The solution behavior of phosphonium gemini surfactants was investigated in chloroform, which is an organic solvent where reverse micellar structures are favored. Solution rheology in chloroform explored the solution behavior of the phosphonium gemini surfactants compared to DTPP. The 12-2-12P and 12-3-12P gemini surfactants were successfully electrospun from chloroform to generate uniform fibers while 12-4-12P gemini surfactant and DTPP only electrosprayed to form droplets.

  2. Astronaut Frank Borman looks over the Gemini 7 spacecraft

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronaut Frank Borman, command pilot of the Gemini 7 prime crew, looks over the Gemini 7 spacecraft during weight and balance tests. The tests are conducted in the Pyrotechnic Installation Building, Merritt Island, Kennedy Space Center as part of preflight preparation.

  3. Current and future facility instruments at the Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Jensen, Joseph B.; Kleinman, Scot J.; Simons, Douglas A.; Lazo, Manuel; Rigaut, François; White, John K.

    2008-07-01

    At the present time, several new Gemini instruments are being delivered and commissioned. The Near-Infrared Coronagraph has been extensively tested and commissioned on the Gemini-South telescope, and will soon begin a large survey to discover extrasolar planets. The FLAMINGOS-2 near-IR multi-object spectrograph is nearing completion at the University of Florida, and is expected to be delivered to Gemini-South by the end of 2008. Gemini's Multi-Conjugate Adaptive Optics bench has been successfully integrated and tested in the lab, and now awaits integration with the laser system and the Gemini-South AO Imager on the telescope. We also describe our efforts to repair thermal damage to the Gemini Near-IR Spectrograph that occurred last year. Since the last update, progress has been made on several of Gemini's next generation of ambitious "Aspen" instruments. The Gemini Planet Imager is now in the final design phase, and construction is scheduled to begin shortly. Two competitive conceptual design studies for the Wide-Field Fiber Multi-Object Spectrometer have now started. The Mauna Kea ground layer monitoring campaign has collected data for well over a year in support of the planning process for a future Ground Layer Adaptive Optics system.

  4. Gemini-Titan 3 water landing recovery in Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Navy swimmers are shown attaching a flotation collar to the Gemini 3 spacecraft during recovery operations following the successful Gemini-Titan 3 flight. A helicopter hovers in the background. Astronauts Virgil I. Grissom and John W. Young are still in the spacecraft.

  5. Manned Space-Flight Experiments: Gemini V Mission

    NASA Technical Reports Server (NTRS)

    1966-01-01

    This compilation of papers constitutes an interim report on the results of experiments conducted during the Gemini V manned space flight. The results of experiments conducted on Gemini III and IV manned space flights have been published previously in a similar interim report, "Manned Space Flight Experiments Symposium, Gemini Missions III and IV," which is available upon request from MSC Experiments Program Office, Houston, Texas (Code EX, Attention of R. Kinard). The Gemini V mission provided the greatest opportunity to date for conducting experiments; the increased mission duration of eight days provided this added capability. The total mission experiment complement was seventeen. Five experiments were designed to obtain basic scientific knowledge, five were medical, and seven were technological and engineering in nature. Six of the experiments had flown previously on Gemini IV, and eleven were new. The results of the experiments, including real-time modification to preflight plans made necessary by abnormal spacecraft system operation, are presented.

  6. The Gemini Planet Imager coronagraph testbed

    NASA Astrophysics Data System (ADS)

    Soummer, Rémi; Sivaramakrishnan, Anand; Oppenheimer, Ben R.; Roberts, Robin; Brenner, Douglas; Carlotti, Alexis; Pueyo, Laurent; Macintosh, Bruce; Bauman, Brian; Saddlemyer, Les; Palmer, David; Erickson, Darren; Dorrer, Christophe; Caputa, Kris; Marois, Christian; Wallace, Kent; Griffiths, Emily; Mey, Jacob

    2009-08-01

    The Gemini Planet Imager (GPI) is a new facility instrument to be commissioned at the 8-m Gemini South telescope in early 2011. It combines of several subsystems including a 1500 subaperture Extreme Adaptive Optics system, an Apodized Pupil Lyot Coronagraph, a near-infrared high-accuracy interferometric wavefront sensor, and an Integral Field Unit Spectrograph, which serves as the science instrument. GPI's main scientific goal is to detect and characterize relatively young (<2GYr), self luminous planets with planet-star brightness ratios of <= 10-7 in the near infrared. Here we present an overview of the coronagraph subsystem, which includes a pupil apodization, a hard-edged focal plane mask and a Lyot stop. We discuss designs optimization, masks fabrication and testing. We describe a near infrared testbed, which achieved broadband contrast (H-band) below 10-6 at separations > 5λ/D, without active wavefront control (no deformable mirror). We use Fresnel propagation modeling to analyze the testbed results.

  7. First light of the Gemini Planet Imager

    DOE PAGES

    Macintosh, Bruce; Graham, James R.; Ingraham, Patrick; ...

    2014-05-12

    The Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 106 at 0.75 arcseconds and 105 at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a singlemore » 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of 9.0+0.8–0.4 AU near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. In conclusion, the observations give a 4% probability of a transit of the planet in late 2017.« less

  8. First light of the Gemini Planet Imager

    SciTech Connect

    Macintosh, Bruce; Graham, James R.; Ingraham, Patrick; Konopacky, Quinn; Marois, Christian; Perrin, Marshall; Poyneer, Lisa; Bauman, Brian; Barman, Travis; Burrows, Adam S.; Cardwell, Andrew; Chilcote, Jeffrey; De Rosa, Robert J.; Dillon, Daren; Doyon, Rene; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Gavel, Donald; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Kalas, Paul; Larkin, James; Maire, Jerome; Marchis, Franck; Marley, Mark S.; McBride, James; Millar-Blanchaer, Max; Morzinski, Katie; Norton, Andrew; Oppenheimer, B. R.; Palmer, David; Patience, Jennifer; Pueyo, Laurent; Rantakyro, Fredrik; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Serio, Andrew; Soummer, Remi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wiktorowicz, Stone; Wolff, Schuyler

    2014-05-12

    The Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 106 at 0.75 arcseconds and 105 at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of 9.0+0.8–0.4 AU near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. In conclusion, the observations give a 4% probability of a transit of the planet in late 2017.

  9. Gemini Planet Imager coronagraph testbed results

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, Anand; Soummer, Rémi; Oppenheimer, Ben R.; Carr, G. Lawrence; Mey, Jacob L.; Brenner, Doug; Mandeville, Charles W.; Zimmerman, Neil; Macintosh, Bruce A.; Graham, James R.; Saddlemyer, Les; Bauman, Brian; Carlotti, Alexis; Pueyo, Laurent; Tuthill, Peter G.; Dorrer, Christophe; Roberts, Robin; Greenbaum, Alexandra

    2010-07-01

    The Gemini Planet Imager (GPI) is an extreme AO coronagraphic integral field unit YJHK spectrograph destined for first light on the 8m Gemini South telescope in 2011. GPI fields a 1500 channel AO system feeding an apodized pupil Lyot coronagraph, and a nIR non-common-path slow wavefront sensor. It targets detection and characterizion of relatively young (<2GYr), self luminous planets up to 10 million times as faint as their primary star. We present the coronagraph subsystem's in-lab performance, and describe the studies required to specify and fabricate the coronagraph. Coronagraphic pupil apodization is implemented with metallic half-tone screens on glass, and the focal plane occulters are deep reactive ion etched holes in optically polished silicon mirrors. Our JH testbed achieves H-band contrast below a million at separations above 5 resolution elements, without using an AO system. We present an overview of the coronagraphic masks and our testbed coronagraphic data. We also demonstrate the performance of an astrometric and photometric grid that enables coronagraphic astrometry relative to the primary star in every exposure, a proven technique that has yielded on-sky precision of the order of a milliarsecond.

  10. First light of the Gemini Planet imager.

    PubMed

    Macintosh, Bruce; Graham, James R; Ingraham, Patrick; Konopacky, Quinn; Marois, Christian; Perrin, Marshall; Poyneer, Lisa; Bauman, Brian; Barman, Travis; Burrows, Adam S; Cardwell, Andrew; Chilcote, Jeffrey; De Rosa, Robert J; Dillon, Daren; Doyon, Rene; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P; Gavel, Donald; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Kalas, Paul; Larkin, James; Maire, Jerome; Marchis, Franck; Marley, Mark S; McBride, James; Millar-Blanchaer, Max; Morzinski, Katie; Norton, Andrew; Oppenheimer, B R; Palmer, David; Patience, Jennifer; Pueyo, Laurent; Rantakyro, Fredrik; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Serio, Andrew; Soummer, Remi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J Kent; Wiktorowicz, Sloane; Wolff, Schuyler

    2014-09-02

    The Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 10(6) at 0.75 arcseconds and 10(5) at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of [Formula: see text] near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. The observations give a 4% probability of a transit of the planet in late 2017.

  11. Gemini Planet Imager Coronagraph Testbed Results

    SciTech Connect

    Sivaranmakrishnan, A.; Carr, G.; Soummer, R.; Oppenheimer, B.R.; Mey, J.L.; Brenner, D.; Mandeville, C.W.; Zimmerman, N. Macintosh, B.A.; Graham, J.R.; Saddlemyer, L.; Bauman, B.; Carlotti, A.; Pueyo, L.; Tuthill, P.G.; Dorrer, C.; Roberts, R.; Greenbaum, A.

    2010-12-08

    The Gemini Planet Imager (GPI) is an extreme AO coronagraphic integral field unit YJHK spectrograph destined for first light on the 8m Gemini South telescope in 2011. GPI fields a 1500 channel AO system feeding an apodized pupil Lyot coronagraph, and a nIR non-common-path slow wavefront sensor. It targets detection and characterizion of relatively young (<2GYr), self luminous planets up to 10 million times as faint as their primary star. We present the coronagraph subsystem's in-lab performance, and describe the studies required to specify and fabricate the coronagraph. Coronagraphic pupil apodization is implemented with metallic half-tone screens on glass, and the focal plane occulters are deep reactive ion etched holes in optically polished silicon mirrors. Our JH testbed achieves H-band contrast below a million at separations above 5 resolution elements, without using an AO system. We present an overview of the coronagraphic masks and our testbed coronagraphic data. We also demonstrate the performance of an astrometric and photometric grid that enables coronagraphic astrometry relative to the primary star in every exposure, a proven technique that has yielded on-sky precision of the order of a milliarsecond.

  12. First light of the Gemini Planet Imager

    PubMed Central

    Macintosh, Bruce; Graham, James R.; Ingraham, Patrick; Konopacky, Quinn; Marois, Christian; Perrin, Marshall; Poyneer, Lisa; Bauman, Brian; Barman, Travis; Burrows, Adam S.; Cardwell, Andrew; Chilcote, Jeffrey; De Rosa, Robert J.; Dillon, Daren; Doyon, Rene; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Gavel, Donald; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Kalas, Paul; Larkin, James; Maire, Jerome; Marchis, Franck; Marley, Mark S.; McBride, James; Millar-Blanchaer, Max; Morzinski, Katie; Norton, Andrew; Oppenheimer, B. R.; Palmer, David; Patience, Jennifer; Pueyo, Laurent; Rantakyro, Fredrik; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Serio, Andrew; Soummer, Remi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wiktorowicz, Sloane; Wolff, Schuyler

    2014-01-01

    The Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 106 at 0.75 arcseconds and 105 at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of 9.0−0.4+0.8 AU near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. The observations give a 4% probability of a transit of the planet in late 2017. PMID:24821792

  13. Mechanically selflocked chiral gemini-catenanes

    PubMed Central

    Li, Sheng-Hua; Zhang, Heng-Yi; Xu, Xiufang; Liu, Yu

    2015-01-01

    Mechanically interlocked and entangled molecular architectures represent one of the elaborate topological superstructures engineered at a molecular resolution. Here we report a methodology for fabricating mechanically selflocked molecules (MSMs) through highly efficient one-step amidation of a pseudorotaxane derived from dual functionalized pillar[5]arene (P[5]A) threaded by α,ω-diaminoalkane (DA-n; n=3–12). The monomeric and dimeric pseudo[1]catenanes thus obtained, which are inherently chiral due to the topology of P[5]A used, were isolated and fully characterized by NMR and circular dichroism spectroscopy, X-ray crystallography and DFT calculations. Of particular interest, the dimeric pseudo[1]catenane, named ‘gemini-catenane', contained stereoisomeric meso-erythro and dl-threo isomers, in which two P[5]A moieties are threaded by two DA-n chains in topologically different patterns. This access to chiral pseudo[1]catenanes and gemini-catenanes will greatly promote the practical use of such sophisticated chiral architectures in supramolecular and materials science and technology. PMID:26126502

  14. Astrometric Calibration of the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Tran, Debby; Konopacky, Quinn M.; GPIES Team

    2017-01-01

    The Gemini Planet Imager (GPI), housed on the 8-meter Gemini South telescope in Chile, is an instrument designed to detect Jupiter-like extrasolar planets by direct imaging. It relies on adaptive optics to correct the effects of atmospheric turbulence, along with an advanced coronagraph and calibration system. One of the scientific goals of GPI is to measure the orbital properties of the planets it discovers. Because these orbits have long periods, precise measurements of the relative position between the star and the planet (relative astrometry) are required. In this poster, I will present the astrometric calibration of GPI. We constrain the plate scale and orientation of the camera by observing different binary star systems with both GPI and another well-calibrated instrument, NIRC2, at the Keck telescope in Hawaii. We measure their separations with both instruments and use that information to calibrate the plate scale. By taking these calibration measurements over the course of one year, we have measured the plate scale to 0.05% and shown that it is stable across multiple epochs. We also examined the effects of the point spread function on the positions of the binaries as well as their separations, the results of which I will discuss.

  15. Photometric Calibration of the Gemini South Adaptive Optics Imager

    NASA Astrophysics Data System (ADS)

    Stevenson, Sarah Anne; Rodrigo Carrasco Damele, Eleazar; Thomas-Osip, Joanna

    2017-01-01

    The Gemini South Adaptive Optics Imager (GSAOI) is an instrument available on the Gemini South telescope at Cerro Pachon, Chile, utilizing the Gemini Multi-Conjugate Adaptive Optics System (GeMS). In order to allow users to easily perform photometry with this instrument and to monitor any changes in the instrument in the future, we seek to set up a process for performing photometric calibration with standard star observations taken across the time of the instrument’s operation. We construct a Python-based pipeline that includes IRAF wrappers for reduction and combines the AstroPy photutils package and original Python scripts with the IRAF apphot and photcal packages to carry out photometry and linear regression fitting. Using the pipeline, we examine standard star observations made with GSAOI on 68 nights between 2013 and 2015 in order to determine the nightly photometric zero points in the J, H, Kshort, and K bands. This work is based on observations obtained at the Gemini Observatory, processed using the Gemini IRAF and gemini_python packages, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

  16. Gemini Observatory Operations and Software for the 2020s

    NASA Astrophysics Data System (ADS)

    Miller, Bryan W.; Stephens, Andrew W.; Nunez, Arturo; Schirmer, Mischa

    2017-01-01

    Gemini Observatory is planning several major software upgrades to improve usability and maintenance and to help prepare Gemini for the LSST, ELT, and JWST era. Gemini is currently a leader in target-of-opportunity (ToO) observing (e.g. SNe and GRB follow-up, solar system objects, eclipses, occultations) due to the dominant queue mode of observing. In the era of large transient surveys (e.g. iPTF, Catalina, Pan-STARRS, and especially LSST) and other transient surveys we expect that the follow-up of faint transient sources will become a very significant, if not dominant, use of Gemini. The next Gemini instrument, Gen4#3, is being designed for transient follow-up. However, much of Gemini's software infrastructure is now more than 15 years old is not sufficiently user-friendly, scalable, or maintainable. Therefore, we are embarking on a series of upgrade projects with the goals of making Gemini easier to use, making the system more scalable and flexible, and ensuring that the system is maintainable for the next 15 years. This poster will describe the ongoing projects and future plans to upgrade the real-time control systems, develop a new Observatory Control System (including a potential rewrite of the Observing Tool and an automated scheduling capability), and integrate into future ToO networks. Feedback on requirements for new user software, in particular, is requested.

  17. Geological interpretation of a Gemini photo

    USGS Publications Warehouse

    Hemphill, William R.; Danilchik, Walter

    1968-01-01

    Study of the Gemini V photograph of the Salt Range and Potwar Plateau, West Pakistan, indicates that small-scale orbital photographs permit recognition of the regional continuity of some geologic features, particularly faults and folds that could he easily overlooked on conventional air photographs of larger scale. Some stratigraphic relationships can also be recognized on the orbital photograph, but with only minimal previous geologic knowledge of the area, these interpretations are less conclusive or reliable than the interpretation of structure. It is suggested that improved atmospheric penetration could be achieved through the use of color infrared film. Photographic expression of topography could also be improved by deliberately photographing some areas during periods of low sun angle.

  18. Wavefront control for the Gemini Planet Imager

    SciTech Connect

    Poyneer, L A; Veran, J; Dillon, D; Severson, S; Macintosh, B

    2006-04-14

    The wavefront control strategy for the proposed Gemini Planet Imager, an extreme adaptive optics coronagraph for planet detection, is presented. Two key parts of this strategy are experimentally verified in a testbed at the Laboratory for Adaptive Optics, which features a 32 x 32 MEMS device. Detailed analytic models and algorithms for Shack-Hartmann wavefront sensor alignment and calibration are presented. It is demonstrated that with these procedures, the spatially filtered WFS and the Fourier Transform reconstructor can be used to flatten to the MEMS to 1 nm RMS in the controllable band. Performance is further improved using the technique of modifying the reference slopes using a measurement of the static wavefront error in the science leg.

  19. Gemini: A long-range cargo transport

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The proposed Gemini, a long-range cargo transport, is designed as a high capacity, dedicated cargo transporter of 8'x8'x20' inter-modal containers, and long-range design. These requirements will result in a design that is larger than any existing aircraft. Due to the size, a conventional configuration would result in an aircraft unable to operate economically at existing airports. It is necessary to design for a minimum possible empty weight, wingspan, and landing gear track. After considering both a single fuselage biplane and a double fuselage biplane configuration, the design team choose the double fuselage biplane configuration. Both of these configuration choices result in a reduced wing root bending moment and subsequently in substantial savings in the wing weight. An overall decrease in the weight of the airplane, its systems, and fuel will be a direct result of the wing weight savings.

  20. The Gemini Planet Imager Exoplanet Survey

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce

    The Gemini Planet Imager (GPI) is a next-generation coronagraph constructed for the Gemini Observatory. GPI will see first light this fall. It will be the most advanced planet-imaging system in operation - an order of magnitude more sensitive than any current instrument, capable of detecting and spectroscopically characterizing young Jovian planets 107 times fainter than their parent star at separations of 0.2 arcseconds. GPI was built from the beginning as a facility-class survey instrument, and the observatory will employ it that way. Our team has been selected by Gemini Observatory to carry out an 890-hour program - the GPI Exoplanet Survey (GPIES) campaign from 2014-2017. We will observe 600 stars spanning spectral types A-M. We will use published young association catalogs and a proprietary list in preparation that adds several hundred new young (<100 Myr, <75 pc) and adolescent (<300 Myr, <35 pc) stars. The range of separations studied by GPI is completely inaccessible to Doppler and transit techniques (even with Kepler or TESS)— GPI offers a new window into planet formation. We will use GPI to produce the first-ever robust census of giant planet populations in the 5-50 AU range, allowing us to: 1) illuminate the formation pathways of Jovian planets; 2) reconstruct the early dynamical evolution of systems, including migration mechanisms and the interaction with disks and belts of debris; and 3) bridge the gap between Jupiter and the brown dwarfs with the first examples of cool low- gravity planetary atmospheres. Simulations predict this survey will discover approximately 50 exoplanets, increasing the number of exoplanet images by an order of magnitude, enough for statistical investigation. This Origins of Solar Systems proposal will support the execution of the GPI Exoplanet Survey campaign. We will develop tools needed to execute the survey efficiently. We will refine the existing GPI data pipeline to a final version that robustly removes residual speckle

  1. Response to major earthquakes affecting Gemini twins

    NASA Astrophysics Data System (ADS)

    van der Hoeven, Michiel; Rogers, Rolando; Rippa, Mathew; Perez, Gabriel; Montes, Vanessa; Moreno, Cristian

    2016-07-01

    Both Gemini telescopes, in Hawaii and Chile, are located in highly seismic active areas. That means that the seismic protection is included in the structural design of the telescope, instruments and auxiliary structure. We will describe the specific design features to reduce permanent damage in case of major earthquakes. At this moment both telescopes have been affected by big earthquakes in 2006 and 2015 respectively. There is an opportunity to compare the original design to the effects that are caused by these earthquakes and analyze their effectiveness. The paper describes the way the telescopes responded to these events, the damage that was caused, how we recovered from it, the modifications we have done to avoid some of this damage in future occasions, and lessons learned to face this type of events. Finally we will cover on how we pretend to upgrade the limited monitoring tools we currently have in place to measure the impact of earthquakes.

  2. Maintaining the Telescope Bibliography at Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Zhang, X.

    2010-10-01

    The library profession benefits tremendously from ever-changing web technologies. In maintaining a telescope bibliography, web-publishing revolutionized the way librarians track relevant publications. Thanks to the search abilities provided by the NASA Astrophysics Data System, arXiv, publishers, as well as Google Scholar, and other such resources, online searching for Gemini-based publications has replaced the tedious perusing of print journals. However, we should keep in mind that online searching is neither flawless nor simple — different content providers require different search strategies. Sometimes the retrievals are not as complete as one expects. Information providers should be constantly improving their searching abilities in order to make the task of electronic publication tracking more reliable and efficient.

  3. Geo-Engineering through Internet Informatics (GEMINI)

    SciTech Connect

    Watney, W. Lynn; Doveton, John H.; Victorine, John R.; Bohling, Goeffrey C.; Bhattacharya, Saibal; Byers, Alan P.; Carr, Timothy R.; Dubois, Martin K.; Gagnon, Glen; Guy, Willard J.; Look, Kurt; Magnuson, Mike; Moore, Melissa; Olea, Ricardo; Pakalapadi, Jayprakash; Stalder, Ken; Collins, David R.

    2002-06-25

    GEMINI will resolve reservoir parameters that control well performance; characterize subtle reservoir properties important in understanding and modeling hydrocarbon pore volume and fluid flow; expedite recognition of bypassed, subtle, and complex oil and gas reservoirs at regional and local scale; differentiate commingled reservoirs; build integrated geologic and engineering model based on real-time, iterate solutions to evaluate reservoir management options for improved recovery; provide practical tools to assist the geoscientist, engineer, and petroleum operator in making their tasks more efficient and effective; enable evaluations to be made at different scales, ranging from individual well, through lease, field, to play and region (scalable information infrastructure); and provide training and technology transfer to evaluate capabilities of the client.

  4. First light of the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce; Graham, James R.; Ingraham, Patrick; Konopacky, Quinn; Marois, Christian; Perrin, Marshall; Poyneer, Lisa; Bauman, Brian; Barman, Travis; Burrows, Adam S.; Cardwell, Andrew; Chilcote, Jeffrey; De Rosa, Robert J.; Dillon, Daren; Doyon, Rene; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Gavel, Donald; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Kalas, Paul; Larkin, James; Maire, Jerome; Marchis, Franck; Marley, Mark S.; McBride, James; Millar-Blanchaer, Max; Morzinski, Katie; Norton, Andrew; Oppenheimer, B. R.; Palmer, David; Patience, Jennifer; Pueyo, Laurent; Rantakyro, Fredrik; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Serio, Andrew; Soummer, Remi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wiktorowicz, Sloane; Wolff, Schuyler

    2014-09-01

    The Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 106 at 0.75 arcseconds and 105 at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of 9.0-0.4+0.8AU near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. The observations give a 4% probability of a transit of the planet in late 2017.

  5. Food packets for use on the Gemini 3 flight

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Food packets for use on the Gemini 3 flight including dehydrated beef pot roast, bacon and egg bites, toasted bread cubes, orange juice and a wet wipe. Water is being inserted into the pouch of dehydrated food.

  6. Food packages for use on the Gemini 4 flight

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Food packages for use on the Gemini 4 flight. Packages include beef and gravy, peaches, strawberry cereal cubes and beef sandwiches. Water gun is used to reconstitute dehydrated food. Scissors are used to open the packages.

  7. View of Gemini 11 experiment S-13 Ultraviolet Astronomical Camera

    NASA Technical Reports Server (NTRS)

    1966-01-01

    View of Gemini 11 experiment S-13 Ultraviolet Astronomical Camera before flight. Its object was to obtain data on ultraviolet radiation of hot stars and to develop and evaluate basic techniques for photography of celestial objects from manned spacecraft.

  8. Gemini enclosure and support facility design philosophy and design description

    NASA Astrophysics Data System (ADS)

    Raybould, Keith; Ford, Robert M.; Gillett, Paul E.; Hardash, Steven G.; Pentland, Gordon

    1994-06-01

    The Gemini project is an international collaboration between the USA, United Kingdom, Canada, Chile, Argentina, and Brazil, to design, fabricate and assemble two 8 M telescopes, one on Mauna Kea in Hawaii, the other on Cerro Pachon in Chile. The telescopes will be national facilities designed to meet the Gemini Science Requirements, a document developed by the Gemini Science Committee. This paper describes the design considerations that influence the scientific performance of the enclosure and support facility, and the features that have been incorporated to meet the demanding science requirements, particularly the 0.026 arc sec allowance for `enclosure seeing'. A description of the Gemini enclosure, support facilities and site plans for Mauna Kea is given here together with a brief description of the analysis and testing that has been performed to establish the performance of the facility.

  9. Dicationic alkylammonium bromide gemini surfactants. Membrane perturbation and skin irritation.

    PubMed

    Almeida, João A S; Faneca, Henrique; Carvalho, Rui A; Marques, Eduardo F; Pais, Alberto A C C

    2011-01-01

    Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For this purpose, keratinocyte cells from human skin (NCTC 2544 cell line), frequently used as a model for skin irritation, were employed. The impact of the different gemini surfactants on the permeability and morphology of model vesicles was additionally investigated by measuring the leakage of calcein fluorescent dye and analyzing the NMR spectra of ³¹P, respectively. Detail on the interaction of gemini molecules with model membranes was also provided by a systematic differential scanning calorimetry (DSC) and molecular dynamics (MD) simulation. An irreversible impact on the viability of the NCTC 2544 cell line was observed for gemini concentrations higher than 25 mM, while no cytotoxicity was found for any of the surfactants in a concentration range up to 10 mM. A higher cytotoxicity was also found for gemini surfactants presenting longer spacer and shorter tails. The same trend was obtained in the calorimetric and permeability studies, with the gemini of longest spacer promoting the highest degree of membrane destabilization. Additional structural and dynamical characterization of the various systems, obtained by ³¹P NMR and MD, provide some insight on the relationship between the architecture of gemini surfactants and the respective perturbation mechanism.

  10. Dicationic Alkylammonium Bromide Gemini Surfactants. Membrane Perturbation and Skin Irritation

    PubMed Central

    Almeida, João A. S.; Faneca, Henrique; Carvalho, Rui A.; Marques, Eduardo F.; Pais, Alberto A. C. C.

    2011-01-01

    Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For this purpose, keratinocyte cells from human skin (NCTC 2544 cell line), frequently used as a model for skin irritation, were employed. The impact of the different gemini surfactants on the permeability and morphology of model vesicles was additionally investigated by measuring the leakage of calcein fluorescent dye and analyzing the NMR spectra of 31P, respectively. Detail on the interaction of gemini molecules with model membranes was also provided by a systematic differential scanning calorimetry (DSC) and molecular dynamics (MD) simulation. An irreversible impact on the viability of the NCTC 2544 cell line was observed for gemini concentrations higher than 25 mM, while no cytotoxicity was found for any of the surfactants in a concentration range up to 10 mM. A higher cytotoxicity was also found for gemini surfactants presenting longer spacer and shorter tails. The same trend was obtained in the calorimetric and permeability studies, with the gemini of longest spacer promoting the highest degree of membrane destabilization. Additional structural and dynamical characterization of the various systems, obtained by 31P NMR and MD, provide some insight on the relationship between the architecture of gemini surfactants and the respective perturbation mechanism. PMID:22102870

  11. GEMINI: integrative exploration of genetic variation and genome annotations.

    PubMed

    Paila, Umadevi; Chapman, Brad A; Kirchner, Rory; Quinlan, Aaron R

    2013-01-01

    Modern DNA sequencing technologies enable geneticists to rapidly identify genetic variation among many human genomes. However, isolating the minority of variants underlying disease remains an important, yet formidable challenge for medical genetics. We have developed GEMINI (GEnome MINIng), a flexible software package for exploring all forms of human genetic variation. Unlike existing tools, GEMINI integrates genetic variation with a diverse and adaptable set of genome annotations (e.g., dbSNP, ENCODE, UCSC, ClinVar, KEGG) into a unified database to facilitate interpretation and data exploration. Whereas other methods provide an inflexible set of variant filters or prioritization methods, GEMINI allows researchers to compose complex queries based on sample genotypes, inheritance patterns, and both pre-installed and custom genome annotations. GEMINI also provides methods for ad hoc queries and data exploration, a simple programming interface for custom analyses that leverage the underlying database, and both command line and graphical tools for common analyses. We demonstrate GEMINI's utility for exploring variation in personal genomes and family based genetic studies, and illustrate its ability to scale to studies involving thousands of human samples. GEMINI is designed for reproducibility and flexibility and our goal is to provide researchers with a standard framework for medical genomics.

  12. New serine-derived gemini surfactants as gene delivery systems.

    PubMed

    Cardoso, Ana M; Morais, Catarina M; Cruz, A Rita; Silva, Sandra G; do Vale, M Luísa; Marques, Eduardo F; de Lima, Maria C Pedroso; Jurado, Amália S

    2015-01-01

    Gemini surfactants have been extensively used for in vitro gene delivery. Amino acid-derived gemini surfactants combine the special aggregation properties characteristic of the gemini surfactants with high biocompatibility and biodegradability. In this work, novel serine-derived gemini surfactants, differing in alkyl chain lengths and in the linker group bridging the spacer to the headgroups (amine, amide and ester), were evaluated for their ability to mediate gene delivery either per se or in combination with helper lipids. Gemini surfactant-based DNA complexes were characterized in terms of hydrodynamic diameter, surface charge, stability in aqueous buffer and ability to protect DNA. Efficient formulations, able to transfect up to 50% of the cells without causing toxicity, were found at very low surfactant/DNA charge ratios (1/1-2/1). The most efficient complexes presented sizes suitable for intravenous administration and negative surface charge, a feature known to preclude potentially adverse interactions with serum components. This work brings forward a new family of gemini surfactants with great potential as gene delivery systems.

  13. GEMINI: Integrative Exploration of Genetic Variation and Genome Annotations

    PubMed Central

    Paila, Umadevi; Chapman, Brad A.; Kirchner, Rory; Quinlan, Aaron R.

    2013-01-01

    Modern DNA sequencing technologies enable geneticists to rapidly identify genetic variation among many human genomes. However, isolating the minority of variants underlying disease remains an important, yet formidable challenge for medical genetics. We have developed GEMINI (GEnome MINIng), a flexible software package for exploring all forms of human genetic variation. Unlike existing tools, GEMINI integrates genetic variation with a diverse and adaptable set of genome annotations (e.g., dbSNP, ENCODE, UCSC, ClinVar, KEGG) into a unified database to facilitate interpretation and data exploration. Whereas other methods provide an inflexible set of variant filters or prioritization methods, GEMINI allows researchers to compose complex queries based on sample genotypes, inheritance patterns, and both pre-installed and custom genome annotations. GEMINI also provides methods for ad hoc queries and data exploration, a simple programming interface for custom analyses that leverage the underlying database, and both command line and graphical tools for common analyses. We demonstrate GEMINI's utility for exploring variation in personal genomes and family based genetic studies, and illustrate its ability to scale to studies involving thousands of human samples. GEMINI is designed for reproducibility and flexibility and our goal is to provide researchers with a standard framework for medical genomics. PMID:23874191

  14. The Gemini Deep Planet Survey - GDPS

    SciTech Connect

    Lafreniere, D; Doyon, R; Marois, C; Nadeau, D; Oppenheimer, B R; Roche, P F; Rigaut, F; Graham, J R; Jayawardhana, R; Johnstone, D; Kalas, P G; Macintosh, B; Racine, R

    2007-06-01

    We present the results of the Gemini Deep Planet Survey, a near-infrared adaptive optics search for giant planets and brown dwarfs around nearby young stars. The observations were obtained with the Altair adaptive optics system at the Gemini North telescope and angular differential imaging was used to suppress the speckle noise of the central star. Detection limits for the 85 stars observed are presented, along with a list of all faint point sources detected around them. Typically, the observations are sensitive to angular separations beyond 0.5-inch with 5{sigma} contrast sensitivities in magnitude difference at 1.6 {micro}m of 9.6 at 0.5-inch, 12.9 at 1-inch, 15 at 2-inch, and 16.6 at 5-inch. For the typical target of the survey, a 100 Myr old K0 star located 22 pc from the Sun, the observations are sensitive enough to detect planets more massive than 2 M{sub Jup} with a projected separation in the range 40-200 AU. Depending on the age, spectral type, and distance of the target stars, the minimum mass that could be detected with our observations can be {approx}1 M{sub Jup}. Second epoch observations of 48 stars with candidates (out of 54) have confirmed that all candidates are unrelated background stars. A detailed statistical analysis of the survey results, which provide upper limits on the fractions of stars with giant planet or low mass brown dwarf companions, is presented. Assuming a planet mass distribution dn/dm {proportional_to} m{sup -1.2} and a semi-major axis distribution dn/da {proportional_to} a{sup -1}, the upper limits on the fraction of stars with at least one planet of mass 0.5-13 M{sub Jup} are 0.29 for the range 10-25 AU, 0.13 for 25-50 AU, and 0.09 for 50-250 AU, with a 95% confidence level; this result is weakly dependent on the semi-major axis distribution power-law index. Without making any assumption on the mass and semi-major axis distributions, the fraction of stars with at least one brown dwarf companion having a semi-major axis in the

  15. The Gemini Planet Imager Exoplanet Survey

    NASA Astrophysics Data System (ADS)

    Nielsen, Eric L.; Macintosh, Bruce; Graham, James R.; Barman, Travis S.; Doyon, Rene; Fabrycky, Daniel; Fitzgerald, Michael P.; Kalas, Paul; Konopacky, Quinn M.; Marchis, Franck; Marley, Mark S.; Marois, Christian; Patience, Jenny; Perrin, Marshall D.; Oppenheimer, Rebecca; Song, Inseok; GPIES Team

    2017-01-01

    The Gemini Planet Imager Exoplanet Survey (GPIES) is one of the largest most sensitive direct imaging searches for exoplanets conducted to date, and having observed more than 300 stars the survey is halfway complete. We present highlights from the first half of the survey, including the discovery and characterization of the young exoplanet 51 Eri b and the brown dwarf HR 2562 B, new imaging of multiple disks, and resolving the young stellar binary V343 Nor for the first time. GPI has also provided new spectra and orbits of previous known planets and brown dwarfs and polarization measurements of a wide range of disks. Finally, we discuss the constraints placed by the first half of the GPIES campaign on the population of giant planets at orbital separations beyond that of Jupiter. Supported by NSF grants AST-0909188 and AST-1313718, AST-1411868, AST 141378, NNX11AF74G, and DGE-1232825, and by NASA grants NNX15AD95G/NEXSS and NNX11AD21G.

  16. Testing of the Gemini secondary mirrors

    NASA Astrophysics Data System (ADS)

    Otto, Wolfgang

    1999-09-01

    The first 1-m secondary mirror for the Gemini 8-m telescopes project was delivered by Zeiss in 1998, and 2nd mirror will be delivered in the summer of 1999. For first use during commissioning we produced an extreme lightweight Zerodur solution prefabricated at Schott. To reach the 85 percent weight reduction a novel etching technique was used. INterferometric testing was done performing full aperture measurements using a concave matrix. In progress with the fabrication process of the matrix we applied 3D-mechanical measurements, IR-interferometry, and VIS-interferometry using null lenses to reach the final intrinsic quality of 6 nm rms. For interferometric testing of the secondaries phase shifting interferometry with a tunable laser diode was applied. The optical test results of the secondaries show, that the mirrors are well within specification. The finally achieved intrinsic surface quality is 17 nm rms for Unit 1 and 13 nm rms for Unit 2, dominated by cutting effects which were introduced by removing the oversize at the inner and outer edge of the mirror after the final polishing step.

  17. Gemini-IFU spectroscopy of HH 111

    SciTech Connect

    Cerqueira, A. H.; Vasconcelos, M. J.; Feitosa, J.; Plana, H.; Raga, A. C.

    2015-03-01

    We present new optical observations of the Herbig–Haro (HH) 111 jet using the Gemini Multi Object Spectrograph in its Integral Field Unit mode. Eight fields of 5{sup ′′}×3.{sup ′′}5 have been positioned along and across the HH 111 jet, covering the spatial region from knot E to L in HH 111 (namely, knots E, F, G, H, J, K, and L). We present images and velocity channel maps for the [O i] 6300+6360, Hα, [N ii] 6548+6583, and [S ii] 6716+6730 lines, as well as for the [S ii] 6716/6730 line ratio. We find that the HH 111 jet has an inner region with lower excitation and higher radial velocity, surrounded by a broader region of higher excitation and lower radial velocity. Also, we find higher electron densities at lower radial velocities. These results imply that the HH 111 jet has a fast, axial region with lower velocity shocks surrounded by a lower velocity sheath with higher velocity shocks.

  18. GEO-ENGINEERING MODELING THROUGH INTERNET INFORMATICS (GEMINI)

    SciTech Connect

    W. Lynn Watney; John H. Doveton

    2004-05-13

    GEMINI (Geo-Engineering Modeling through Internet Informatics) is a public-domain web application focused on analysis and modeling of petroleum reservoirs and plays (http://www.kgs.ukans.edu/Gemini/index.html). GEMINI creates a virtual project by ''on-the-fly'' assembly and analysis of on-line data either from the Kansas Geological Survey or uploaded from the user. GEMINI's suite of geological and engineering web applications for reservoir analysis include: (1) petrofacies-based core and log modeling using an interactive relational rock catalog and log analysis modules; (2) a well profile module; (3) interactive cross sections to display ''marked'' wireline logs; (4) deterministic gridding and mapping of petrophysical data; (5) calculation and mapping of layer volumetrics; (6) material balance calculations; (7) PVT calculator; (8) DST analyst, (9) automated hydrocarbon association navigator (KHAN) for database mining, and (10) tutorial and help functions. The Kansas Hydrocarbon Association Navigator (KHAN) utilizes petrophysical databases to estimate hydrocarbon pay or other constituent at a play- or field-scale. Databases analyzed and displayed include digital logs, core analysis and photos, DST, and production data. GEMINI accommodates distant collaborations using secure password protection and authorized access. Assembled data, analyses, charts, and maps can readily be moved to other applications. GEMINI's target audience includes small independents and consultants seeking to find, quantitatively characterize, and develop subtle and bypassed pays by leveraging the growing base of digital data resources. Participating companies involved in the testing and evaluation of GEMINI included Anadarko, BP, Conoco-Phillips, Lario, Mull, Murfin, and Pioneer Resources.

  19. Novel gemini cationic lipids with carbamate groups for gene delivery.

    PubMed

    Zhao, Yi-Nan; Qureshi, Farooq; Zhang, Shu-Biao; Cui, Shao-Hui; Wang, Bing; Chen, Hui-Ying; Lv, Hong-Tao; Zhang, Shu-Fen; Huang, Leaf

    2014-05-21

    To obtain efficient non-viral vectors, a series of Gemini cationic lipids with carbamate linkers between headgroups and hydrophobic tails were synthesized. They have the hydrocarbon chains of 12, 14, 16 and 18 carbon atoms as tails, designated as G12, G14, G16 and G18, respectively. These Gemini cationic lipids were prepared into cationic liposomes for the study of the physicochemical properties and gene delivery. The DNA-bonding ability of these Gemini cationic liposomes was much better than their mono-head counterparts (designated as M12, M14, M16 and M18, respectively). In the same series of liposomes, bonding ability declined with an increase in tail length. They were tested for their gene-transferring capabilities in Hep-2 and A549 cells. They showed higher transfection efficiency than their mono-head counterparts and were comparable or superior in transfection efficiency and cytotoxicity to the commercial liposomes, DOTAP and Lipofectamine 2000. Our results convincingly demonstrate that the gene-transferring capabilities of these cationic lipids depended on hydrocarbon chain length. Gene transfection efficiency was maximal at a chain length of 14, as G14 can silence about 80 % of luciferase in A549 cells. Cell uptake results indicate that Gemini lipid delivery systems could be internalised by cells very efficiently. Thus, the Gemini cationic lipids could be used as synthetic non-viral gene delivery carriers for further study.

  20. Novel gemini cationic lipids with carbamate groups for gene delivery

    PubMed Central

    Zhao, Yi-Nan; Qureshi, Farooq; Zhang, Shu-Biao; Cui, Shao-Hui; Wang, Bing; Chen, Hui-Ying; Lv, Hong-Tao; Zhang, Shu-Fen; Huang, Leaf

    2014-01-01

    To obtain efficient non-viral vectors, a series of Gemini cationic lipids with carbamate linkers between headgroups and hydrophobic tails were synthesized. They have the hydrocarbon chains of 12, 14, 16 and 18 carbon atoms as tails, designated as G12, G14, G16 and G18, respectively. These Gemini cationic lipids were prepared into cationic liposomes for the study of the physicochemical properties and gene delivery. The DNA-bonding ability of these Gemini cationic liposomes was much better than their mono-head counterparts (designated as M12, M14, M16 and M18, respectively). In the same series of liposomes, bonding ability declined with an increase in tail length. They were tested for their gene-transferring capabilities in Hep-2 and A549 cells. They showed higher transfection efficiency than their mono-head counterparts and were comparable or superior in transfection efficiency and cytotoxicity to the commercial liposomes, DOTAP and Lipofectamine 2000. Our results convincingly demonstrate that the gene-transferring capabilities of these cationic lipids depended on hydrocarbon chain length. Gene transfection efficiency was maximal at a chain length of 14, as G14 can silence about 80 % of luciferase in A549 cells. Cell uptake results indicate that Gemini lipid delivery systems could be internalised by cells very efficiently. Thus, the Gemini cationic lipids could be used as synthetic non-viral gene delivery carriers for further study. PMID:25045521

  1. Sky Background Variability Measured on Maunakea at Gemini North Observatory

    NASA Astrophysics Data System (ADS)

    Smith, Adam B.; Roth, Katherine; Stephens, Andrew W.

    2016-01-01

    Gemini North has recently implemented a Quality Assessment Pipeline (QAP) that automatically reduces images in realtime to determine sky condition quantities, including background sky brightness from the optical to near-infrared. Processing archived images through the QAP and mining the results allows us to look for trends and systematic issues with the instruments and optics during the first decade of Gemini.Here we present the results of using the QAP calculated values to quantify how airglow affects the background sky brightness of images taken with Gemini's imaging instruments, GMOS and NIRI, as well as searching for other factors that may cause changes in the sky brightness. By investigating the dependence of measured sky brightness as a function of a variety of variables, including time after twilight, airmass, season, distance from the moon, air temperature, etc., we quantify the effect of sky brightness and its impact on the sensitivity of Gemini optical and near-infrared imaging data. These measurements will be used to determine new sky background relationships for Maunakea, and to improve the Gemini Integration Time Calculators (ITCs).

  2. Gemini imidazolium surfactants: synthesis and their biophysiochemical study.

    PubMed

    Kamboj, Raman; Singh, Sukhprit; Bhadani, Avinash; Kataria, Hardeep; Kaur, Gurcharan

    2012-08-21

    New gemini imidazolium surfactants 9-13 have been synthesized by a regioselective epoxy ring-opening reaction under solvent-free conditions. The surface properties of these new gemini surfactants were evaluated by surface tension and conductivity measurements. These surfactants have been found to have low critical micelle concentration (cmc) values as compared to other categories of gemini cationic surfactants and also showed the tendency to form premicellar aggregates in solution at sufficiently low concentration below their cmc values. The thermal degradation of these surfactants was determined by thermograviometry analysis (TGA). These new cationic surfactants have a good DNA binding capability as determined by agarose gel electrophoresis and ethidium bromide exclusion experiments. They have also been found to have low cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the C6 glioma cell line.

  3. 78 FR 70097 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel GEMINI; Invitation for Public...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Maritime Administration Requested Administrative Waiver of the Coastwise Trade Laws: Vessel GEMINI... of the vessel GEMINI is: Intended Commercial Use Of Vessel: ``S/V Gemini to be used as an...

  4. U.S.S. Intrepid alongside Gemini 3 spacecraft after landing

    NASA Technical Reports Server (NTRS)

    1965-01-01

    The U.S.S. Intrepid pulls up alongside the Gemini 3 spacecraft during recovery operations following the successful Gemini-Titan 3 flight. Navy swimmers stand on the spacecraft's flotation collar waiting to hook a hoist line to the Gemini 3.

  5. Thermal emissivity analysis of a GEMINI 8-meter telescopes design

    NASA Technical Reports Server (NTRS)

    St. Clair Dinger, Ann

    1993-01-01

    The GEMINI 8-meter Telescopes Project is designing twin 8-meter telescopes to be located in Hawaii and Chile. The GEMINI telescopes will have interchangeable secondary mirrors for use in the visible and IR. The APART/PADE program is being used to evaluate the effective IR emissivity of the IR configuration plus enclosure as a function of mirror contamination at three IR wavelengths. The goal is to design a telescope whose effective IR emissivity is no more than 2 percent when the mirrors are clean.

  6. Gemini 4 astronauts relax aboard Navy helicopter after recovery

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Gemini 4 astronauts, James A. McDivitt (right), command pilot, and Edward H. White II, (left), pilot, relax aboard a U.S. Navy helicopter on their way to the aircraft carrier U.S.S. Wasp after recovery from the Gemini 4 spacecraft. They had been picked up out of the Atlantic Ocean following a successful splashdown (33532); White (left) and McDivitt listen to the voice of President Lyndon B. Johnson as he congratulated them by telephone on the successful mission. They are shown aboard the carrier U.S.S. Wasp just after their recovery (33533).

  7. The Gemini Planet Imager: From Science to Design to Construction

    SciTech Connect

    Macintosh, B; Graham, J R; Palmer, D; Doyon, R; Dunn, J; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Sivaramakrishnan, A; Wallace, J K; Bauman, B; Erickson, D; Marois, C; Poyneer, L; Soummer, R

    2008-07-01

    The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. It combines a 1500 subaperture AO system using a MEMS deformable mirror, an apodized-pupil Lyot coronagraph, a high-accuracy IR interferometer calibration system, and a near-infrared integral field spectrograph to allow detection and characterization of self-luminous extrasolar planets at planet/star contrast ratios of 10{sup -7}. I will discuss the evolution from science requirements through modeling to the final detailed design, provide an overview of the subsystems and show models of the instrument's predicted performance.

  8. Performance of the Gemini Planet Imager's adaptive optics system.

    PubMed

    Poyneer, Lisa A; Palmer, David W; Macintosh, Bruce; Savransky, Dmitry; Sadakuni, Naru; Thomas, Sandrine; Véran, Jean-Pierre; Follette, Katherine B; Greenbaum, Alexandra Z; Ammons, S Mark; Bailey, Vanessa P; Bauman, Brian; Cardwell, Andrew; Dillon, Daren; Gavel, Donald; Hartung, Markus; Hibon, Pascale; Perrin, Marshall D; Rantakyrö, Fredrik T; Sivaramakrishnan, Anand; Wang, Jason J

    2016-01-10

    The Gemini Planet Imager's adaptive optics (AO) subsystem was designed specifically to facilitate high-contrast imaging. A definitive description of the system's algorithms and technologies as built is given. 564 AO telemetry measurements from the Gemini Planet Imager Exoplanet Survey campaign are analyzed. The modal gain optimizer tracks changes in atmospheric conditions. Science observations show that image quality can be improved with the use of both the spatially filtered wavefront sensor and linear-quadratic-Gaussian control of vibration. The error budget indicates that for all targets and atmospheric conditions AO bandwidth error is the largest term.

  9. Gemini Observatory base facility operations: systems engineering process and lessons learned

    NASA Astrophysics Data System (ADS)

    Serio, Andrew; Cordova, Martin; Arriagada, Gustavo; Adamson, Andy; Close, Madeline; Coulson, Dolores; Nitta, Atsuko; Nunez, Arturo

    2016-08-01

    Gemini North Observatory successfully began nighttime remote operations from the Hilo Base Facility control room in November 2015. The implementation of the Gemini North Base Facility Operations (BFO) products was a great learning experience for many of our employees, including the author of this paper, the BFO Systems Engineer. In this paper we focus on the tailored Systems Engineering processes used for the project, the various software tools used in project support, and finally discuss the lessons learned from the Gemini North implementation. This experience and the lessons learned will be used both to aid our implementation of the Gemini South BFO in 2016, and in future technical projects at Gemini Observatory.

  10. Gemini Series Experiment Data Reduction and Storage Techniques

    SciTech Connect

    R. A. Berglin

    2011-11-01

    The presentation covers data formats expected from Gemini experiments; data quick look vs. in-depth analysis; iPDV object-oriented data storage; iPDV's traceability of analysis results; optimizing object memory usage in iPDV; and long-term archival of data objects by iPDV.

  11. Designing Scalable PGAS Communication Subsystems on Cray Gemini Interconnect

    SciTech Connect

    Vishnu, Abhinav; Daily, Jeffrey A.; Palmer, Bruce J.

    2012-12-26

    The Cray Gemini Interconnect has been recently introduced as a next generation network architecture for building multi-petaflop supercomputers. Cray XE6 systems including LANL Cielo, NERSC Hopper, ORNL Titan and proposed NCSA BlueWaters leverage the Gemini Interconnect as their primary Interconnection network. At the same time, programming models such as the Message Passing Interface (MPI) and Partitioned Global Address Space (PGAS) models such as Unified Parallel C (UPC) and Co-Array Fortran (CAF) have become available on these systems. Global Arrays is a popular PGAS model used in a variety of application domains including hydrodynamics, chemistry and visualization. Global Arrays uses Aggregate Re- mote Memory Copy Interface (ARMCI) as the communication runtime system for Remote Memory Access communication. This paper presents a design, implementation and performance evaluation of scalable and high performance communication subsystems on Cray Gemini Interconnect using ARMCI. The design space is explored and time-space complexities of commu- nication protocols for one-sided communication primitives such as contiguous and uniformly non-contiguous datatypes, atomic memory operations (AMOs) and memory synchronization is presented. An implementation of the proposed design (referred as ARMCI-Gemini) demonstrates the efficacy on communication primitives, application kernels such as LU decomposition and full applications such as Smooth Particle Hydrodynamics (SPH) application.

  12. Illustration of relative sizes of Mercury, Gemini and Apollo spacecraft

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Artist concept illustrating the relative sizes of the one-man Mercury spacecraft, the two-man Gemini spacecraft, and the three-man Apollo spacecraft. Also shows line drawing of launch vehichles to show their relative size in relation to each other.

  13. Remote Operations of Laser Guide Star Systems: Gemini Observatory.

    NASA Astrophysics Data System (ADS)

    Oram, Richard J.; Fesquet, Vincent; Wyman, Robert; D'Orgeville, Celine

    2011-03-01

    The Gemini North telescope, equipped with a 14W laser, has been providing Laser Guide Star Adaptive Optics (LGS AO) regular science queue observations for worldwide astronomers since February 2007. The new 55W laser system for MCAO was installed on the Gemini South telescope in May 2010. In this paper, we comment on how Gemini Observatory developed regular remote operation of the Laser Guide Star Facility and high-power solid-state laser as routine normal operations. Fully remote operation of the LGSF from the Hilo base facility HBF was initially trialed and then optimized and became the standard operating procedure (SOP) for LGS operation in December 2008. From an engineering perspective remote operation demands stable, well characterized and base-lined equipment sets. In the effort to produce consistent, stable and controlled laser parameters (power, wavelength and beam quality) we completed a failure mode effect analysis of the laser system and sub systems that initiated a campaign of hardware upgrades and procedural improvements to the routine maintenance operations. Finally, we provide an overview of normal operation procedures during LGS runs and present a snapshot of data accumulated over several years that describes the overall LGS AO observing efficiency at the Gemini North telescope.

  14. Gemini 12 crew arrives aboard U.S.S. Wasp

    NASA Technical Reports Server (NTRS)

    1966-01-01

    A happy Gemini 12 prime crew arrives aboard the aircraft carrier, U.S.S. Wasp. Astronauts James A. Lovell Jr. (left), command pilot, and Edwin E. Aldrin Jr., pilot, had just been picked up from the splashdown area by helicopter.

  15. Astronaut David Scott practicing for Gemini 8 EVA

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronaut David R. Scott practicing for Gemini 8 extravehicular acitivity (EVA) in bldg 4 of the Manned Spacecraft Center on the air bearing floor. He is wearing the the Hand-Held Maneuvering Unit which he will use during the EVA.

  16. Gemini photographs of the world: A complete index

    NASA Technical Reports Server (NTRS)

    Giddings, L. E.

    1977-01-01

    The most authoritative catalogs of photographs of all Gemini missions are assembled. Included for all photographs are JSC (Johnson Space Center) identification number, percent cloud cover, geographical area in sight, and miscellaneous information. In addition, details are given on cameras, filters, films, and other technical details.

  17. Overhead view of the Gemini spacecraft during final inspection

    NASA Technical Reports Server (NTRS)

    1965-01-01

    McDonnell Aircraft Corp, technicians can be seen making final adjustments and inspection prior to leaving the white room atop the Titan launch vehicle at Pad 19, Cape Kennedy. The Gemini-Titan 3 spacecraft is being prepared for launch.

  18. Gemini high-resolution optical spectrograph conceptual design

    NASA Astrophysics Data System (ADS)

    Szeto, Kei; McConnachie, Alan; Anthony, André; Bohlender, David; Crampton, David; Desaulniers, Pierre; Dunn, Jennifer; Hardy, Tim; Hill, Alexis; Monin, Dmitry; Pazder, John; Schwab, Christian; Spano, Paola; Starkenburg, Else; Thibault, Simon; Walker, Gordon; Venn, Kim; Zhang, Hu

    2012-09-01

    A multiplexed moderate resolution (R = 34,000) and a single object high resolution (R = 90,000) spectroscopic facility for the entire 340 - 950nm wavelength region has been designed for Gemini. The result is a high throughput, versatile instrument that will enable precision spectroscopy for decades to come. The extended wavelength coverage for these relatively high spectral resolutions is achieved by use of an Echelle grating with VPH cross-dispersers and for the R = 90,000 mode utilization of an image slicer. The design incorporates a fast, efficient, reliable system for acquiring targets over the7 arcmin field of Gemini. This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study.

  19. Classification of 3 DES supernovae by Gemini-North

    NASA Astrophysics Data System (ADS)

    Pan, Y.-C.; Foley, R. J.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Casas, R.; Castander, F. J.; Desai, S.; Paech, K.; Smith, R. C.; Schubnell, M.; Kessler, R.; Lasker, J.; Scolnic, D.; Brout, D. J.; Gladney, L.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.; Childress, M.; D'Andrea, C.; Smith, M.; Sullivan, M.

    2015-11-01

    We report optical spectroscopy of 3 supernovae discovered by the Dark Energy Survey. The spectra (380-820nm) were obtained using GMOS on Gemini-North. Object classification was performed using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) and superfit (Howell et al, 2005, ApJ, 634, 119), the details of which are reported in the table below.

  20. Antibacterial activity and characteristics of modified ferrite powder coated with a gemini pyridinium salt molecule.

    PubMed

    Shirai, Akihiro; Maeda, Takuya; Ohkita, Motoaki; Nagamune, Hideaki; Kourai, Hiroki

    2007-09-01

    This report describes the synthesis of an antibacterial material consisting of a gemini quaternary ammonium salt (gemini-QUAT) immobilized on ferrite powder, and its antibacterial activity. A gemini-QUAT containing two pyridinium residues per molecule, 4,4'-[1,3-(2,2-dihydroxylmethyl-1,3-dithiapropane)]bis (1-octylpyridinium bromide), was immobilized on ferrite powder by a reaction between the hydroxyl group of the QUAT and trimethoxysilane. Immobilization of the gemini-QUAT on ferrite (F-gemini-QUAT) was confirmed when the dye, bromophenol blue, was released from F-gemini-QUAT-dye after contact between ferrite and the dye. Elemental analysis of the QUAT-ferrite determined the molar amount of QUAT on the ferrite. The antibacterial effect of the ferrite was investigated using a batch treatment system, and this effect was compared with that of another QUAT-ferrite (F-mono-QUAT) binding a mono-QUAT, which possesses one pyridinium residue, prepared by the same immobilization method as F-gemini-QUAT. Results indicated the F-gemini QUAT possessed a higher bactericidal potency and broader antibacterial spectrum compared to F-mono-QUAT. In addition, this study suggested that gemini-QUATs possessed high bactericidal potency without being influenced by immobilization to materials, and the antibacterial activity and characteristics of F-gemini-QUAT could be attributed to the unique structure of the immobilized gemini-QUAT.

  1. A novel type of highly effective nonionic gemini alkyl O-glucoside surfactants: a versatile strategy of design.

    PubMed

    Liu, Songbai; Sang, Ruocheng; Hong, Shan; Cai, Yujing; Wang, Hua

    2013-07-09

    A novel type of highly effective gemini alkyl glucosides has been rationally designed and synthesized. The gemini surfactants have been readily prepared by glycosylation of the gemini alkyl chains that are synthesized with regioselective ring-opening of ethylene glycol epoxides by the alkyl alcohols. The new gemini alkyl glucosides exhibit significantly better surface activity than the known results. Then rheological, DLS, and TEM studies have revealed the intriguing self-assembly behavior of the novel gemini surfactants. This study has proved the effectiveness of the design of gemini alkyl glucosides which is modular, extendable, and synthetically simple. The new gemini surfactants have great potential as nano carriers in drug and gene delivery.

  2. Gemini Planet Imager: Preliminary Design Report

    SciTech Connect

    Macintosh, B

    2007-05-10

    For the first time in history, direct and indirect detection techniques have enabled the exploration of the environments of nearby stars on scales comparable to the size of our solar system. Precision Doppler measurements have led to the discovery of the first extrasolar planets, while high-contrast imaging has revealed new classes of objects including dusty circumstellar debris disks and brown dwarfs. The ability to recover spectrophotometry for a handful of transiting exoplanets through secondary-eclipse measurements has allowed us to begin to study exoplanets as individual entities rather than points on a mass/semi-major-axis diagram and led to new models of planetary atmospheres and interiors, even though such measurements are only available at low SNR and for a handful of planets that are automatically those most modified by their parent star. These discoveries have galvanized public interest in science and technology and have led to profound new insights into the formation and evolution of planetary systems, and they have set the stage for the next steps--direct detection and characterization of extrasolar Jovian planets with instruments such as the Gemini Planet Imager (GPI). As discussed in Volume 1, the ability to directly detect Jovian planets opens up new regions of extrasolar planet phase space that in turn will inform our understanding of the processes through which these systems form, while near-IR spectra will advance our understanding of planetary physics. Studies of circumstellar debris disks using GPI's polarimetric mode will trace the presence of otherwise-invisible low-mass planets and measure the build-up and destruction of planetesimals. To accomplish the science mission of GPI will require a dedicated instrument capable of achieving contrast of 10{sup -7} or more. This is vastly better than that delivered by existing astronomical AO systems. Currently achievable contrast, about 10{sup -5} at separations of 1 arc second or larger, is

  3. Novel fluorinated gemini surfactants with γ-butyrolactone segments.

    PubMed

    Kawase, Tokuzo; Okada, Kazuyuki; Oida, Tatsuo

    2015-01-01

    In this work, novel γ-butyrolactone-type monomeric and dimeric (gemini) surfactants with a semifluoroalkyl group [Rf- (CH2)3-; Rf = C4F9, C6F13, C8F17] as the hydrophobic group were successfully synthesized. Dimethyl malonate was dimerized or connected using Br(CH2)sBr (s = 0, 1, 2, 3) to give tetraesters, and they were bis-allylated. Radical addition of fluoroalkyl using Rf-I and an initiator, i.e., 2,2'-azobisisobutyronitrile for C4F9 or di-t-butyl peroxide for C6F13 and C8F17, was perform at high temperature, with prolonged heating, to obtain bis(semifluoroalkyl)-dilactone diesters. These dilactone diesters were hydrolyzed using KOH/EtOH followed by decarboxylation in AcOH to afford γ-butyrolactonetype gemini surfactants. Common 1 + 1 semifluoroalkyl lactone surfactants were synthesized using the same method. Their surfactant properties [critical micelle concentration (CMC), γCMC, pC20, ΓCMC, and AG] were investigated by measuring the surface tension of the γ-hydroxybutyrate form prepared in aqueous tetrabutylammonium hydroxide solution. As expected, the CMC values of the gemini surfactants were more than one order of magnitude smaller than those of the corresponding 1 + 1 surfactants. Other properties also showed the excellent ability of the gemini structure to reduce the surface tension. These surfactants were easily and quantitatively recovered by acidification. The monomeric surfactant was recovered in the γ-hydroxybutyric acid form, and the gemini surfactant as a mixture of γ-butyrolactone and γ-hydroxybutyric acid forms.

  4. Characterizing Dusty Debris Disks with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Chen, Christine; Arriaga, Pauline; Bruzzone, Sebastian; Choquet, Elodie; Debes, John H.; Donaldson, Jessica; Draper, Zachary; Duchene, Gaspard; Esposito, Thomas; Fitzgerald, Michael P.; Golimowski, David A.; Hines, Dean C.; Hinkley, Sasha; Hughes, A. Meredith; Kalas, Paul; Kolokolova, Ludmilla; Lawler, Samantha; Matthews, Brenda C.; Mazoyer, Johan; Metchev, Stanimir A.; Millar-Blanchaer, Max; Moro-Martin, Amaya; Nesvold, Erika; Padgett, Deborah; Patience, Jenny; Perrin, Marshall D.; Pueyo, Laurent; Rantakyro, Fredrik; Rodigas, Timothy; Schneider, Glenn; Soummer, Remi; Song, Inseok; Stark, Chris; Weinberger, Alycia J.; Wilner, David J.

    2017-01-01

    We have been awarded 87 hours of Gemini Observatory time to obtain multi-wavelength observations of HST resolved debris disks using the Gemini Planet Imager. We have executed ~51 hours of telescope time during the 2015B-2016B semesters observing 12 nearby, young debris disks. We have been using the GPI Spec and Pol modes to better constrain the properties of the circumstellar dust, specifically, measuring the near-infrared total intensity and polarization fraction colors, and searching for solid-state spectral features of nearby beta Pic-like disks. We expect that our observations will allow us to break the degeneracy among the particle properties such as composition, size, porosity, and shape. We present some early results from our observations.

  5. Gemini surfactants mediate efficient mitochondrial gene delivery and expression.

    PubMed

    Cardoso, Ana M; Morais, Catarina M; Cruz, A Rita; Cardoso, Ana L; Silva, Sandra G; do Vale, M Luísa; Marques, Eduardo F; Pedroso de Lima, Maria C; Jurado, Amália S

    2015-03-02

    Gene delivery targeting mitochondria has the potential to transform the therapeutic landscape of mitochondrial genetic diseases. Taking advantage of the nonuniversal genetic code used by mitochondria, a plasmid DNA construct able to be specifically expressed in these organelles was designed by including a codon, which codes for an amino acid only if read by the mitochondrial ribosomes. In the present work, gemini surfactants were shown to successfully deliver plasmid DNA to mitochondria. Gemini surfactant-based DNA complexes were taken up by cells through a variety of routes, including endocytic pathways, and showed propensity for inducing membrane destabilization under acidic conditions, thus facilitating cytoplasmic release of DNA. Furthermore, the complexes interacted extensively with lipid membrane models mimicking the composition of the mitochondrial membrane, which predicts a favored interaction of the complexes with mitochondria in the intracellular environment. This work unravels new possibilities for gene therapy toward mitochondrial diseases.

  6. Antibacterial Activity of Alanine-Derived Gemini Quaternary Ammonium Compounds.

    PubMed

    Piecuch, Agata; Obłąk, Ewa; Guz-Regner, Katarzyna

    The antibacterial activity of alanine-derived gemini quaternary ammonium salts (chlorides and bromides) with various spacer and alkyl chain lengths was investigated. The studied compounds exhibited a strong bactericidal effect, especially bromides with 10 and 12 carbon alkyl chains and 3 carbon spacer groups (TMPAL-10 Br and TMPAL-12 Br), with a short contact time. Both salts dislodged biofilms of Pseudomonas aeruginosa and Staphylococcus epidermidis, and were lethal to adherent cells of S. epidermidis. Bromide with 2 carbon spacer groups and 12 carbon alkyl chains (TMEAL-12 Br) effectively reduced microbial adhesion by coating polystyrene and silicone surfaces. The results obtained suggest that, after further studies, gemini QAS might be considered as antimicrobial agents in medicine or industry.

  7. The Gemini Planet Imager Coronagraph Testbed Preliminary Performance Results

    NASA Astrophysics Data System (ADS)

    Roberts, Robin

    2010-01-01

    The Gemini Planet Imager (GPI) is a new science instrument being developed and slated for first light early 2011 on the twin 8m Gemini telescopes. Operating in the near infrared, this ground-based, extreme Adaptive Optics (ExAO) coronographic instrument will provide the ability to detect, characterize and analyze young (< 2GYr), self-luminous, extrasolar planets with brightness contrast ratios ≤ 10-7 when compared to their parent star. The coronagraph subsystem includes a pupil apodization, a hard-edged focal plane mask as well as a Lyot stop. Preliminary results indicate that the testbed is performing at very high contrast, having achieved broadband contrasts (H-band) below 10-6 at separations > 5λ/D. Fraunhoffer and Fresnel propagation modeling were used to analyze the testbed results.

  8. Observations of Beta Pictoris b with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Chilcote, J.; Graham, J.; Barman, T.; Fitzgerald, M.; Larkin, J.; Macintosh, B.; Bauman, B.; Burrows, A.; Cardwell, A.; De Rosa, R.; Dillon, D.; Doyon, R.; Dunn, J.; Erikson, D.; Gavel, D.; Goodsell, S.; Hartung, M.; Hibon, P.; Ingraham, P.; Kalas, P.; Konopacky, Q.; Maire, J.; Marchis, F.; Marley, M.; Mcbride, J.; Millar-Blanchaer, M.; Morzinski, K.; Norton, A.; Oppenheimer, B.; Palmer, D.; Patience, J.; Pueyo, L.; Rantakyro, F.; Sadakuni, N.; Saddlemyer, L.; Savransky, D.; Serio, A.; Soummer, R.; Sivaramakrishnan, A.; Song, I.; Thomas, S.; Wallace, K.; Wiktorowicz, S.; Wolff, S.

    2014-09-01

    Using the recently installed Gemini Planet Imager (GPI), we present measurements of the planetary companion to the nearby young star beta Pic. GPI is a facility class instrument located at Gemini South designed to image and provide low-resolution spectra of Jupiter sized, self-luminous planetary companions around young nearby stars. We present the current imaged spectrum and atmospheric models of the planet based upon GPI's R ˜50 integral field spectrograph. Further, we present a joint analysis of the GPI and NACO astrometry, and the Snellen et al. (2014) radial velocity measurement of beta Pic b that provides the first constraint on the argument of periastron, providing a causal link to the infalling, evaporating bodies.

  9. Kinetics of aqueous lubrication in the hydrophilic hydrogel Gemini interface.

    PubMed

    Dunn, Alison C; Pitenis, Angela A; Urueña, Juan M; Schulze, Kyle D; Angelini, Thomas E; Sawyer, W Gregory

    2015-12-01

    The exquisite sliding interfaces in the human body share the common feature of hydrated dilute polymer mesh networks. These networks, especially when they constitute a sliding interface such as the pre-corneal tear film on the ocular interface, are described by the molecular weight of the polymer chains and a characteristic size of a minimum structural unit, the mesh size, ξ. In a Gemini interface where hydrophilic hydrogels are slid against each other, the aqueous lubrication behavior has been shown to be a function of sliding velocity, introducing a sliding timescale competing against the time scales of polymer fluctuation and relaxation at the surface. In this work, we examine two recent studies and postulate that when the Gemini interface slips faster than the single-chain relaxation time, chains must relax, suppressing the amplitude of the polymer chain thermal fluctuations.

  10. Gemini's instrumentation program: latest results and long-range plan

    NASA Astrophysics Data System (ADS)

    Boccas, Maxime; Kleinman, S. J.; Goodsell, Stephen; Tollestrup, Eric; Adamson, Andrew; Arriagada, Gustavo; Christou, Julian; Gonzalez, Patricio; Hanna, Kevin; Hartung, Markus; Lazo, Manuel; Mason, Rachel; Neichel, Benoît; Perez, Gabriel; Simons, Doug; Walls, Brian; White, John

    2012-09-01

    The Gemini Observatory is going through an extraordinary time with astronomical instrumentation. New powerful capabilities are delivered and are soon entering scientific operations. In parallel, new instruments are being planned and designed to align the strategy with community needs and enhance the competitiveness of the Observatory for the next decade. We will give a broad overview of the instrumentation program, focusing on achievements, challenges and strategies within a scientific, technical and management perspective. In particular we will discuss the following instruments and projects (some will have dedicated detailed papers in this conference): GMOS-CCD refurbishment, FLAMINGOS-2, GeMS (MCAO system and imager GSAOI), GPI, new generation of A&G, GRACES (fiber feed to CFHT ESPaDOnS) and GHOS (Gemini High-resolution Optical Spectrograph), and provide some updates about detector controllers, mid-IR instruments, Altair, GNIRS, GLAO and future workhorse instruments.

  11. Aqueous Gemini Surfactant Self-Assembly into Complex Lyotropic Phases

    NASA Astrophysics Data System (ADS)

    Mahanthappa, Mahesh; Sorenson, Gregory

    2012-02-01

    In spite of the potentially wide-ranging applications of aqueous bicontinuous lyotropic liquid crystals (LLCs), the discovery of amphiphiles that reliably form these non-constant mean curvature morphologies over large phase windows remains largely serendipitous. Recent work has established that cationic gemini surfactants exhibit a pronounced tendency to form bicontinuous cubic (e.g. gyroid) phases as compared to their parent single-tail amphiphiles. The universality of this phenomenon in other surfactant systems remains untested. In this paper, we will report the aqueous LLC phase behavior of a new class of anionic gemini surfactants derived from long chain carboxylic acids. Our studies show that these new surfactants favor the formation of non-constant mean curvature gyroid and primitive (``Plumber's Nightmare'') structures over amphiphile concentration windows up to 20 wt% wide. Based on these observations, we will discuss insights gained into the delicate force balance governing the self-assembly of these surfactants into aqueous bicontinuous LLCs.

  12. Measurements of airglow on Maunakea at Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Roth, Katherine C.; Smith, Adam; Stephens, Andrew; Smirnova, Olesja

    2016-07-01

    Gemini Observatory on Maunakea has been collecting optical and infrared science data for almost 15 years. We have begun a program to analyze imaging data from two of the original facility instruments, GMOS and NIRI, in order to measure sky brightness levels in multiple infrared and optical broad-band filters. The present work includes data from mid-2016 back through late-2008. We present measured background levels as a function of several operational quantities (e.g. moon phase, hours from twilight, season). We find that airglow is a significant contributor to background levels in several filters. Gemini is primarily a queue scheduled telescope, with observations being optimally executed in order to provide the most efficient use of telescope time. We find that while most parameters are well-understood, the atmospheric airglow remains challenging to predict. This makes it difficult to schedule observations which require dark skies in these filters, and we suggest improvements to ensure data quality.

  13. Astrometric Calibration of the Gemini NICI Planet-Finding Campaign

    NASA Astrophysics Data System (ADS)

    Hayward, Thomas L.; Biller, Beth A.; Liu, Michael C.; Nielsen, Eric L.; Wahhaj, Zahed; Chun, Mark; Ftaclas, Christ; Hartung, Markus; Toomey, Douglas W.

    2014-12-01

    We describe the astrometric calibration of the Gemini NICI Planet-Finding Campaign. The Campaign requires a relative astrometric accuracy of $\\approx$ 20 mas across multi-year timescales in order to distinguish true companions from background stars by verifying common proper motion and parallax with their parent stars. The calibration consists of a correction for instrumental optical image distortion, plus on-sky imaging of astrometric fields to determine the pixel scale and image orientation. We achieve an accuracy of $\\lesssim 7$ mas between the center and edge of the 18$''$ NICI field, meeting the 20 mas requirement. Most of the Campaign data in the Gemini Science Archive are accurate to this level but we identify a number of anomalies and present methods to correct the errors.

  14. Gemini Observatory Takes its Local Communities on an Expanding Journey

    NASA Astrophysics Data System (ADS)

    Harvey, Janice; Michaud, Peter

    2012-08-01

    Currently in its 7th year (2011) Hawaii's annual Journey through the Universe (JttU) program is a flagship Gemini Observatory public education/outreach initiative involving a broad cross-section of the local Hawai'i Island astronomical community, the public, educators, businesses, local government officials, and thousands of local students. This paper describes the program, its history, planning, implementation, as well as the program's objectives and philosophy. The success of this program is documented here, as measured by continuous and expanding engagement of educators, the community, and the public, along with formal evaluation feedback and selected informal verbal testimony. The program's success also serves as justification for the planned adaptation of a version of the program in Chile in 2011 (adapted for Chilean educational and cultural differences). Finally, lessons learned are shared which have refined the program for Gemini's host communities but can also apply to any institution wishing to initiate a similar program.

  15. Visible Spectroscopic Observation Of Asteroid 162173 (1999ju3) With The Gemini-s Telescope

    NASA Astrophysics Data System (ADS)

    Sugita, Seiji; Kuroda, D.; Kameda, S.; Hasegawa, S.; Kamata, S.; Abe, M.; Ishiguro, M.; Takato, N.; Yoshikawa, M.

    2012-10-01

    Asteroid 162173 (1999JU3; hereafter JU3) is the target of the Hayabusa-2 mission. Its visible reflectance spectra have been observed a few times [1,2], and obtained spectra exhibit a wide variety of spectral patterns ranging from a spectra with absorption in the UV region (May 1999) to a flat spectrum with a faint broad absorption centered around 0.6 microns (September 2007) and that with UV absorption and strong broad absorption centered around 0.7 micron (July 2007). The apparent large spectral variation may be due to variegation on the asteroid surface. Such variegation would make a large influence on remote sensing strategy for Hayabusa-2 before its sampling operations. In order to better constraint the spectral properties of JU3, we conducted visible spectroscopic observations at the GEMINI-South observatory 8.1-m telescope with the GMOS instrument. We could obtain three different sets of data in June and July 2012. Although the JU3 rotation phases of two of the observation are close to each other, the other is about 120 degrees away from the two. Our preliminary analyses indicate that these three spectra are slightly reddish but generally flat across the observed wavelength range (0.47 - 0.89 microns). The observed flat spectra are most similar to the spectrum obtained in September 2007, which probably has the highest signal-to-noise ratio among the previous three spectra. This result suggests that material with a flat spectrum probably covers a dominant proportion of the JU3 surface and that the other two types of previously obtained spectra may not cover a very large fraction of the JU3 surface. [1] Binzel, R. P. et al. (2001) Icarus, 151, 139-149; [2] Vilas, F. (2008) AJ, 135, 1101-1105.

  16. On the Shoulders of Titans: A History of Project Gemini

    NASA Technical Reports Server (NTRS)

    Hacker, B. C.

    1977-01-01

    Gemini was the intermediate manned space flight program between America's first steps into space with Mercury and the manned lunar expeditions of Apollo. Because of its position between these two other efforts, Gemini is probably less remembered. Still, it more than had its place in man's progress into this new frontier. Gemini accomplishments were manyfold. They included many firsts: first astronaut-controlled maneuvering in space; first rendezvous in space of one spacecraft with another; first docking of one spacecraft with a propulsive stage and use of that stage to transfer man to high altitude; first traverse of man into the earth's radiation belts; first extended manned flights of a week or more in duration; first extended stays of man outside his spacecraft; first controlled reentry and precision landing; and many more. These achievements were significant in ways one cannot truly evaluate even today, but two things stand out: (1) it was the time when America caught up and surpassed the Soviet Union in manned space flight, and (2) these demonstrations of capability were an absolute prerequisite to the phenomenal Apollo accomplishments then yet to come.

  17. Photometric Calibrations of Gemini Images of NGC 6253

    NASA Astrophysics Data System (ADS)

    Pearce, Sean; Jeffery, Elizabeth

    2017-01-01

    We present preliminary results of our analysis of the metal-rich open cluster NGC 6253 using imaging data from GMOS on the Gemini-South Observatory. These data are part of a larger project to observe the effects of high metallicity on white dwarf cooling processes, especially the white dwarf cooling age, which have important implications on the processes of stellar evolution. To standardize the Gemini photometry, we have also secured imaging data of both the cluster and standard star fields using the 0.6-m SARA Observatory at CTIO. By analyzing and comparing the standard star fields of both the SARA data and the published Gemini zero-points of the standard star fields, we will calibrate the data obtained for the cluster. These calibrations are an important part of the project to obtain a standardized deep color-magnitude diagram to analyze the cluster. We present the process of verifying our standardization process. With a standardized CMD, we also present an analysis of the cluster's main sequence turn off age.

  18. Easier Phase IIs: Recent Improvements to the Gemini User Tools

    NASA Astrophysics Data System (ADS)

    Miller, Bryan; Nuñez, A.

    2013-01-01

    During 2011 and 2012 Gemini Observatory undertook a significant project to improve the software tools used by investigators to propose for and prepare observations. The main goal was to make the definition of observation details (the Phase II process) easier and faster. The main initiatives included rewriting the observing proposal tool (Phase I Tool) and making several major improvements to the Observing Tool, including automatic settings for arc and flat exposures, automatic guide star selection for all instruments and wavefront sensors, and more complete initial template observations with capabilities for simultaneous editing of many observations. This poster explains these major changes as well as outlines future development plans. The Gemini Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  19. A Virtual Field Trip to the Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Fisher, R. Scott; Michaud, P. D.

    2010-01-01

    Live from Gemini (LfG) is a virtual field trip using video conferencing technology to connect primary, secondary and post-secondary students with scientists and educators at the Gemini Observatory. As a pilot project, LfG is rapidly becoming one of the observatory's most often-requested educational programs for learners of all ages. The program aligns exceptionally well with national science (and technology) standards, as well as existing school curricula. This combination makes it easy for teachers to justify participation in the program, especially as the necessary video conferencing technology becomes ever more ubiquitous in classrooms and technology learning centers around the world. In developing and testing this pilot project, a programmatic approach and philosophy evolved that includes post-field-trip educational materials, multi-disciplinary subject matter (astronomy, geology, mathematics, meteorology, engineering and even language - the program is offered in Spanish from Gemini South in Chile), and the establishment of a personal connection and rapport with students. The presenters work to create a comfortable interaction despite the perceived technological barriers. The authors’ experiences with the LfG pilot project convince us that this model is viable for almost any astronomical observatory and should be considered by any dynamic, technology- and education-oriented facility.

  20. Gemini surfactants affect the structure, stability, and activity of ribonuclease Sa.

    PubMed

    Amiri, Razieh; Bordbar, Abdol-Khalegh; Laurents, Douglas V

    2014-09-11

    Gemini surfactants have important advantages, e.g., low micromolar CMCs and slow millisecond monomer ↔ micelle kinetics, for membrane mimetics and for delivering nucleic acids for gene therapy or RNA silencing. However, as a prerequisite, it is important to characterize interactions occurring between Gemini surfactants and proteins. Here NMR and CD spectroscopies are employed to investigate the interactions of cationic Gemini surfactants with RNase Sa, a negatively charged ribonuclease. We find that RNase Sa binds Gemini surfactant monomers and micelles at pH values above 4 to form aggregates. Below pH 4, where the protein is positively charged, these aggregates dissolve and interactions are undetectable. Thermal denaturation experiments show that surfactant lowers RNase Sa's conformational stability, suggesting that surfactant binds the protein's denatured state preferentially. Finally, Gemini surfactants were found to bind RNA, leading to the formation of large complexes. Interestingly, Gemini surfactant binding did not prevent RNase Sa from cleaving RNA.

  1. Aggregation behavior of gemini surfactants and their interaction with macromolecules in aqueous solution.

    PubMed

    Han, Yuchun; Wang, Yilin

    2011-02-14

    Gemini surfactants are constructed by two hydrophobic chains and two polar/ionic head groups covalently connected by a spacer group at the level of the head groups. Gemini surfactants possess unique structural variations and display special aggregate transitions. Their aggregation ability and aggregate structures can be more effectively adjusted through changing their molecular structures compared with the corresponding monomeric surfactants. Moreover, gemini surfactants exhibit special and useful properties while interacting with polymers and biomacromolecules. Their strong self-aggregation ability can be applied to effectively influence the aggregation behavior of both polymers and biomacromolecules. This short review is focused on the performances of gemini surfactants in aqueous solutions investigated in the last few years, and summarizes the effects of molecular structures on aggregation behavior of gemini surfactants in aqueous solution as well as the interaction of gemini surfactants with polymers and biomacromolecules respectively.

  2. Gemini 9-A spacecraft touches down in the Atlantic at end of mission

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Gemini 9-A space flight is concluded as the Gemini 9 spacecraft touches down in the Atlantic. In this view its parachute is still deployed as the spacecraft hits the water (34117); Astronauts Thomas Stafford (right) and Eugene Cernan wave to the crowd aboard the aircraft carrier U.S.S. Wasp as they emerge from their Gemini 9 capsule. John C. Stonesifer (far right), with the Manned Spacecraft Center's Landing and Recovery Division, was on board to greet the astronauts (34118).

  3. Gemini 7 prime crew during suiting up procedures at Launch Complex 16

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronaut James A. Lovell Jr. (left), Gemini 7 prime crew pilot, talks with NASA space suit technician Clyde Teague during suiting up procedures at Launch Complex 16, Kennedy Space Center. Lovell wears the new lightweight space suit planned for use during the Gemini 7 mission (61756); Astronaut Frank Borman, comand pilot of the Gemini 7 space flight, undergoes suiting up operations in Launch Complex 16 during prelaunch countdown. Medical biosensors are attached to his scalp (61757).

  4. Novel Synthesis of Anionic Gemini Surfactants from 1, 4-Diol as a Key Block Material.

    PubMed

    Kawase, Tokuzo; Nakagawa, Mami; Higuchi, Yuuya; Oida, Tatsuo

    2015-01-01

    In this study, a series of all-hydrocarbon anionic gemini surfactants containing COOH (adipic acid-type and suberic acid-type), SO3Na, OSO3Na, and OP=O(OH)2 functional groups was developed from 1,4-diol and 1,4-diketone as a key block material. The effect of the surfactant head groups on the surface properties was investigated by surface tension and surface pressure-area (π-A) measurements. We found that the critical micelle concentrations (CMC) of the studied geminis were smaller by one order of magnitude than those of the corresponding 1+l-type surfactants. From π-A measurements, the limiting areas of COOH-type geminis were less than twofold of the area of the corresponding 1+1-type, which indicates that the gemini structure enabled tighter packing than is possible in surfactants of the 1+l-type. In contrast, the limiting area of the OP=O(OH)2-type gemini was larger than those of the COOH-type geminis. Furthermore, the suberic acid-type gemini showed a smaller limiting area than that of adipic acid-type gemini. Therefore, we can conclude that the flexibility of the gemini at the connecting position has a significant effect on formation of the monolayer at the air/water interface.

  5. Impact of phospholipids on plasmid packaging and toxicity of gemini nanoparticles.

    PubMed

    Dong, Chilbert; Badea, Ildiko; Poorghorban, Masoomeh; Verrall, Ronald; Foldvari, Marianna

    2015-12-07

    Understanding the relationship of structural modifications on the assembly and disassembly of synthetic or non-viral gene delivery is crucial with regard to their rational development. This study describes the use of fluorescence correlation spectroscopy (FCS), as a new tool, to investigate the effect of systematic chemical modifications to dicationic N,N-bis(dimethylalkyl)-α,ω-alkanediammonium surfactants (gemini surfactants) on the self-assembly and physical properties of a series of gemini nanoparticles (gemini NPs). A systematic screening of 27 gemini-plasmid (GP) complexes and gemini NPs showed that their final morphology is governed by the pre-compaction of plasmid by the gemini surfactants. The assembly process of gemini-plasmid intermediate complex (GP) and the final gemini NP (or gemini-plasmid-lipid complex, GPL) was monitored by the tracking of the Cy5-labeled plasmid. Based on diffusion properties, GP complexes were larger than gemini NPs (300-500 nm for GP and 200-300 nm for GPLs). Stoichiometric analysis of the raw intensity histograms showed that both GPs and GPLs particles were composed of multiple plasmids. The final GPLs contain fewer plasmids (2-20 per particle) compared to the intermediate GP (5-35 per particle). The addition of phospholipids dispersed and stabilized GPs to form GPL, but the type of phospholipid (DOPE or DD 1:3) had little effect on the final size of the particles. The FCS data were both validated and complemented by the results of studies of dynamic light scattering (DLS), atomic force microscopy (AFM), X-ray scattering and dye-exclusion assays. A model for gemini NP assembly involving supramolecular aggregate intermediates is proposed.

  6. Synergistic adsorption of mixtures of cationic gemini and nonionic sugar-based surfactant on silica.

    PubMed

    Zhou, Qiong; Somasundaran, P

    2009-03-15

    Adsorption behavior of cationic C(12)-C(4)-C(12) gemini surfactant on silica has been investigated, along with that of nonionic surfactant n-dodecyl-beta-D-maltoside (DM). While DM alone shows meager adsorption on silica, because of the lack of any electrostatic adsorption, cationic gemini adsorbs significantly on the oppositely charged silica surface. Due to the electrostatic nature of cationic gemini adsorption on silica, solution pH affects adsorption of C(12)-C(4)-C(12) gemini dramatically. Meanwhile, C(12)-C(4)-C(12) gemini hemimicelle size at silica/water interface does not seem to change with solution pH. For the mixtures of DM and cationic C(12)-C(4)-C(12) gemini, there is a sharp increase of DM adsorption at silica/water interface, up to 100 times more than DM alone. After mixing with DM, saturation adsorption of cationic C(12)-C(4)-C(12) gemini decreases, due to competition for adsorption sites from DM. At the same time, in its mixture with DM, there is an increased adsorption of C(12)-C(4)-C(12) gemini in the rising part of the adsorption isotherm. Hydrophobic chain-chain interactions, especially with two hydrophobic chains in one C(12)-C(4)-C(12) gemini molecule, and adsorbed C(12)-C(4)-C(12) gemini molecule acting as an anchor or nucleation sites for forming mixed aggregates with DM on silica surface, are attributed to the marked adsorption synergy between DM and cationic C(12)-C(4)-C(12) gemini. The adsorption of surfactants and their mixtures has a marked effect on silica surface charge and silica's wettability.

  7. Impact of phospholipids on plasmid packaging and toxicity of gemini nanoparticles

    PubMed Central

    Dong, Chilbert; Badea, Ildiko; Poorghorban, Masoomeh; Verrall, Ronald; Foldvari, Marianna

    2015-01-01

    Understanding the relationship of structural modifications on the assembly and disassembly of synthetic or non-viral gene delivery is crucial with regard to their rational development. This study describes the use of fluorescence correlation spectroscopy (FCS), as a new tool, to investigate the effect of systematic chemical modifications to dicationic N,N-bis(dimethylalkyl)-α,ω-alkanediammonium surfactants (gemini surfactants) on the self-assembly and physical properties of a series of gemini nanoparticles (gemini NPs). A systematic screening of 27 gemini-plasmid (GP) complexes and gemini NPs showed that their final morphology is governed by the pre-compaction of plasmid by the gemini surfactants. The assembly process of gemini-plasmid intermediate complex (GP) and the final gemini NP (or gemini-plasmid-lipid complex, GPL) was monitored by the tracking of the Cy5-labeled plasmid. Based on diffusion properties, GP complexes were larger than gemini NPs (300–500 nm for GP and 200–300 nm for GPLs). Stoichiometric analysis of the raw intensity histograms showed that both GPs and GPLs particles were composed of multiple plasmids. The final GPLs contain fewer plasmids (2–20 per particle) compared to the intermediate GP (5–35 per particle). The addition of phospholipids dispersed and stabilized GPs to form GPL, but the type of phospholipid (DOPE or DD 1:3) had little effect on the final size of the particles. The FCS data were both validated and complemented by the results of studies of dynamic light scattering (DLS), atomic force microscopy (AFM), X-ray scattering and dye-exclusion assays. A model for gemini NP assembly involving supramolecular aggregate intermediates is proposed. PMID:26693021

  8. Organizational transformation to improve operational efficiency at Gemini South

    NASA Astrophysics Data System (ADS)

    van der Hoeven, M.; Maltes, Diego; Rogers, Rolando

    2016-07-01

    In this paper we will describe how the Gemini South Engineering team has been reorganized from different functional units into a cross-disciplinary team while executing a transition plan that imposes several staff reductions, driven by budget reductions. Several factors are of critical importance to the success of any change in organization. Budgetary processes, staff diversity, leadership style, skill sets and planning are all important factors to take into account to achieve a successful outcome. We will analyze the organizational alignment by using some proven management models and concepts.

  9. Post-Coronagraph Wavefront Sensor for Gemini Planet Imager

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Burruss, Rick; Pueyo, Laurent; Soummer, Remi; Shelton, Chris; Bartos, Randall; Fregoso, Felipe; Nemati, Bijan; Best, Paul; Angione, John

    2009-01-01

    The calibration wavefront system for the Gemini Planet Imager (GPI) will measure the complex wavefront at the apodized pupil and provide slow phase errors to the AO system to mitigate against image plane speckles that would cause a loss in contrast. This talk describes both the low-order and high-order sensors in the calibration wavefront sensor and how the information is combined to form the wavefront estimate before the coronagraph. We will show laboratory results from our calibration testbed that demonstrate the subsystem performance at levels commensurate with those required on the final instrument.

  10. Gemini all-sky camera for laser guide star operation

    NASA Astrophysics Data System (ADS)

    Bec, Matthieu; Rigaut, Francois J.; Trancho, Gelys; Boccas, Maxime; Collao, Fabian; Daruich, Felipe; d'Orgeville, Céline; Lazo, Manuel; Maltes, Diego; Perez, Gabriel; Vergara, Vicente; Vucina, Tomislav; Sheehan, Michael P.

    2008-07-01

    As part of its Safe Aircraft Localization and Satellite Acquisition System (SALSA), Gemini is building an All Sky Camera (ASCAM) system to detect aircrafts in order to prevent propagation of the laser that could be a safety hazard for pilots and passengers. ASCAM detections, including trajectory parameters, are made available to neighbor observatories so they may compute impact parameters given their location. We present in this paper an overview of the system architecture, a description of the software solution and detection algorithm, some performance and on-sky result.

  11. Participación argentina en el Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Cellone, S. A.; Faifer, F. R.; Smith-Castelli, A. V.; Ferreiro, D.; Ferrero, G.

    Since the beginning of the present century; Argentina has access to two twin telescopes each 8.1m in diameter. The Observatory covers both celestial hemispheres; and is equipped with modern instrumentation spanning from the optical to the mid-infrared. This paper gives a brief description of present instruments as well as those available in the near future; pointing to their possible impact on different research lines. The present situation of the Argentine participation in Gemini is illustrated with a few relevant statistical data; focusing the attention on the new agreement that should be signed by all the partners in 2015. FULL TEXT IN SPANISH

  12. Sharing the skies: the Gemini Observatory international time allocation process

    NASA Astrophysics Data System (ADS)

    Margheim, Steven J.

    2016-07-01

    Gemini Observatory serves a diverse community of four partner countries (United States, Canada, Brazil, and Argentina), two hosts (Chile and University of Hawaii), and limited-term partnerships (currently Australia and the Republic of Korea). Observing time is available via multiple opportunities including Large and Long Pro- grams, Fast-turnaround programs, and regular semester queue programs. The slate of programs for observation each semester must be created by merging programs from these multiple, conflicting sources. This paper de- scribes the time allocation process used to schedule the overall science program for the semester, with emphasis on the International Time Allocation Committee and the software applications used.

  13. Gemini amphiphiles regulated photopolymerization of diacetylene acid in organized molecular films.

    PubMed

    Zhong, Ling; Jiao, Tifeng; Liu, Minghua

    2009-07-02

    In this paper, we have investigated the photopolymerization of an amphiphilic diacetylene, 10,12-pentacosadiynoic acid (PCDA), in organized molecular films in the presence of a series of gemini amphiphiles with different spacer lengths. It has been found that, when gemini amphiphiles were mixed with the diacetylene, the film-forming properties were greatly improved and the photopolymerization could be regulated by the gemini amphiphiles. Miscibility and Fourier transform infrared spectroscopy (FT-IR) investigations revealed that the polymerization of PCDA in a mixed film was regulated by the mixing ratio and spacer length of the gemini amphiphiles. Although a slight amount of gemini amphiphile did not make the PCDA polymerize into blue films, the increment of the gemini amphiphile with the short spacer length in the mixed film caused the formation of a red film, and the intensity of red phase to blue phase can be modulated by changing the mixing ratios. When gemini amphiphiles with longer spacer lengths were mixed, blue films were predominantly obtained in all mixing ratios. A mechanism including the interaction between the headgroup of the gemini amphiphiles and the diacetylene and the regulation of the spacer was proposed.

  14. Adsorptive removal of naphthalene induced by structurally different Gemini surfactants in a soil-water system.

    PubMed

    Wei, Jia; Li, Jun; Huang, Guohe; Wang, Xiujie; Chen, Guanghui; Zhao, Baihang

    2016-09-01

    A new generation of surfactant, Gemini surfactants, have been synthesized and have attracted the attention of various industrial and academic research groups. This study focused on the use of symmetric and dissymmetric quaternary ammonium Gemini surfactants to immobilize naphthalene onto soil particles, and is used as an example of an innovative application to remove HOC in situ using the surfactant-enhanced sorption zone. The sorption capacity of modified soils by Gemini surfactant and natural soils was compared and the naphthalene sorption efficiency, in the absence and presence of Gemini surfactants with different alkyl chain lengths, was investigated in the soil-water system. The results have shown that the increased added Gemini surfactant formed admicelles at the interface of soil/water having superior capability to retard contaminant. Symmetric and dissymmetric Gemini surfactants have opposite effect on the aspect of removing of PAH attributing to their solubilization and sorption behavior in soil-water system. Compared with the natural soil, sorption of naphthalene by Gemini-modified soil is noticeably enhanced following the order of C12-2-16 < C12-2-12 < C12-2-8. However, the symmetric Gemini surfactant C12-2-12 is the optimized one for in situ barrier remediation, which is not only has relative high retention ability but also low dosage.

  15. 75 FR 14644 - Gemini Investors IV, L.P., Notice Seeking Exemption Under Section 312 of the Small Business...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-26

    ... ADMINISTRATION Gemini Investors IV, L.P., Notice Seeking Exemption Under Section 312 of the Small Business Investment Act, Conflicts of Interest Notice is hereby given that Gemini Investors IV, L.P., 20 William... Business Administration (``SBA'') Rules and Regulations (13 CFR 107.730). Gemini Investors IV,...

  16. Vedolizumab for ulcerative colitis and Crohn's disease: results and implications of GEMINI studies.

    PubMed

    Lam, Mindy Cw; Bressler, Brian

    2014-01-01

    Vedolizumab (VDZ) is a selective antibody against α4β7-integrin, which targets leukocyte trafficking in the gastrointestinal tract. The GEMINI studies are Phase 3, randomized, placebo-controlled trials to assess the efficacy of VDZ in induction and maintenance of moderately to severely active ulcerative colitis (GEMINI 1) and Crohn's disease (GEMINI 2). Included in these studies are patients who have failed TNF-α antagonist therapy. GEMINI 1 showed that VDZ is an effective agent in induction and maintenance of ulcerative colitis. GEMINI 2 met one of two primary end points in the induction phase showing that VDZ is more likely to induce clinical remission compared with placebo. VDZ is an effective agent in the maintenance of Crohn's disease. These studies pave the way to a new class of medications for treatment of inflammatory bowel disease.

  17. Optical contamination evidence from Skylab and Gemini flights

    NASA Technical Reports Server (NTRS)

    Muscari, J. A.; Westcott, P.

    1975-01-01

    Final results from a part of the T027 experiment performed on the first Skylab mission are presented. The sample array system containing 248 optical surfaces and exposed outside the orbital workshop did not collect any significant contaminants. Unfortunate performance compromises and the relative cleanliness of the assembly on the antisolar side placed the amount of available surface contaminants at or below the limiting sensitivity of the ground measuring instruments. Significant contamination was seen near the extravehicular hatch quadrant on the solar side of the orbiting assembly, and some results from returned samples are presented. Optical windows and mirrors exposed on the Gemini 12 mission showed degradation up to 35% in the UV wavelength region and solar absorptance increases up to 1.8 times the clean values. An expression for the attenuation coefficient vs wavelength is presented. The contaminant, a silicone base material, varied in thickness from 22 nm to 88 nm. The postflight scattered luminance of a contaminated Gemini 12 left-hand spacecraft hatch window was used to obtain threshold stellar visibility curves as a function of scattered and incident sunlight angles.

  18. Gemini North Laser Guide Star System: operations and maintenance review

    NASA Astrophysics Data System (ADS)

    Oram, Richard J.; Fesquet, Vincent; Wyman, Robert; d'Orgeville, Celine

    2010-07-01

    The Gemini North telescope has been providing Laser Guide Star Adaptive Optics (LGS AO) regular science queue observations for worldwide astronomers since February 2007. In this paper we comment on the reliability of the Laser Guide Star Facility high-power solid-state laser during normal operations, and discuss progress made on various issues that will enable a "turn-key" operation mode for the laser system. In this effort to produce consistent, stable and controlled laser parameters (power, wavelength and beam quality) we completed a failure mode effect analysis of the laser system and sub systems that initiated a campaign of hardware upgrades and procedural improvements to the routine maintenance operations. These upgrades are discussed, including pump laser diode replacements, as well as sum frequency generation (SFG) crystal degradation along with our detailed plans to improve overall laser reliability, and availability. Finally, we provide an overview of normal operation procedures during LGS runs and present a snapshot of data accumulated over several years that describes the overall LGS AO observing efficiency at the Gemini North telescope.

  19. Optical contamination evidence from Skylab and Gemini flights.

    PubMed

    Muscari, J A; Westcott, P

    1975-12-01

    Final results from a part of the T027 experiment that was performed on the first Skylab mission are presented. The sample array system containing 248 optical surfaces and exposed outside the orbital workshop did not collect any significant contaminants. Unfortunate performance compromises and the relative cleanliness of the assembly on the antisolar side placed the amount of available surface contaminants at or below the limiting sensitivity of the ground measuring instruments. However, significant contamination was seen near the extravehicular hatch quadrant on the solar side of the orbiting assembly, and some results from returned samples are presented. Optical windows and mirrors exposed on the Gemini 12 mission showed degradation up to 35% in the uv wavelength region and solar absorptance increases up to 1.8 times the clean values. An expression for the attenuation coefficient vs wavelength is presented. The contaminant, a silicone base material, varied in thickness from 22 nm to 88 nm. The postflight sca ttered luminance of a contaminated Gemini 12 left-hand spacecraft hatch window was used to obtain threshold stellar visibility curves as a function of scattered and incident sunlight angles.

  20. Science with OCTOCAM: a new workhorse instrument proposed for Gemini

    NASA Astrophysics Data System (ADS)

    Thöne, Christina C.; de Ugarte Postigo, Antonio; van der Horst, Alexander; Roming, Pete

    2016-08-01

    OCTOCAM is an 8-channel VIS-IR (g to K-band) simultaneous imager and medium-resolution spectrograph proposed as new workhorse instrument for the 8m Gemini telescopes. It also offers additional observing modes of high time resolution, integral-field spectroscopy and spectropolarimetry, making it a very versatile instrument for many science cases in the 2020ies. A special focus of OCTOCAM will be the detection and follow-up of transient sources such as gamma-ray bursts, supernovae, magnetars, active galactic nuclei and yet to be discovered new objects, delivered by large-scale surveys like LSST available in the 2020ies. The diverse nature of transients will require the full range of OCTOCAM capabilities allowing more information in very short time about the source than with any other current instrument and adaptable almost in real time. Another main science topic will be to probe the high redshift Universe and the first stars for which OCTOCAM will be highly suited due to its wide wavelength coverage and high sensitivity. However, OCTOCAM is also suited for a large range of other science cases including transneptunian objects, exoplanets, stellar evolution and supermassive black holes. Our science team comprises more than 50 researchers reflecting the large interest of the Gemini community in the capabilities of OCTOCAM. We will highlight a few important science cases demonstrating the different capabilities of OCTOCAM and their need for the scientific community.

  1. Evaluating the Potential of Cray Gemini Interconnect for PGAS Communication Runtime Systems

    SciTech Connect

    Vishnu, Abhinav; ten Bruggencate, Monika; Olson, Ryan M.

    2011-08-24

    The Cray Gemini Interconnect has been recently introduced as the next generation network for building scalable multi-petascale supercomputers. The Cray XE6 systems, which use the Gemini Interconnect are becoming available with Message Passing Interface (MPI) and Partitioned Global Address Space (PGAS) Models such as as Global Arrays, Unified Parallel C, Co-Array Fortran and Cascade High Performance Language. These PGAS models use one-sided communication runtime systems such as MPI-Remote Memory Access, Aggregate Remote Memory Copy Interface and proprietary communication runtime systems. The primary objective of our work is to study the potential of Cray Gemini Interconnect by designing application specific micro-benchmarks using the DMAPP userspace library provided by the Gemini Interconnect. To meet this objective, we design micro-benchmarks to study the performance of simple communication primitives and application specific micro-benchmarks to understand the behavior of Gemini Interconnect at scale. In our experiments, the Gemini Interconnect can achieve a peak bandwidth of 6911 MB/s and a latency of 1us for get communication primitive. Scalability tests for atomic memory operations and shift communication operation up to 65536 processes shows the efficacy of the Gemini Interconnect.

  2. Interactions of gemini surfactants with two model proteins: NMR, CD, and fluorescence spectroscopies.

    PubMed

    Amiri, Razieh; Bordbar, Abdol-Khalegh; García-Mayoral, Ma Flor; Khosropour, Ahmad Reza; Mohammadpoor-Baltork, Iraj; Menéndez, Margarita; Laurents, Douglas V

    2012-03-01

    Gemini surfactants have two polar head groups and two hydrocarbon tails. Compared with conventional surfactants, geminis have much lower (μM vs. mM) critical micelle concentrations and possess slower (ms vs. μs) monomer <-- / --> micelle kinetics. The structure of the gemini surfactants studied is [HOCH(2)CH(2)-, CH(3)-, CH(3)(CH(2))(15)-N(+)-(CH(2))(s)-N(+)-(CH(2))(15)CH(3),-CH(3),-CH(2)CH(2)OH]·2Br(-) where s=4, 5, or 6. Our objective is to reveal the effect of these cationic gemini surfactants on the structure and stability of two model proteins: Ribonuclease A (RNase A) and Hen Egg White Lysozyme (HEWL). 2D (1)H NMR and Circular Dichroism (CD) spectroscopies show that the conformation of RNase A and HEWL is unaffected at low to neutral pH where these proteins are positively charged, although hydrogen exchange shows that RNase A's conformational stability is slightly lowered. At alkaline pH, where these proteins lose their net positive charge, fluorescence and CD spectroscopies and ITC experiments show that they do interact with gemini surfactants, and multiple protein•gemini complexes are observed. Based on the results, we conclude that these cationic gemini surfactants neither interact strongly with nor severely destabilize these well folded proteins in physiological conditions, and we advance that they can serve as useful membrane mimetics for studying the interactions between membrane components and positively charged proteins.

  3. Enhanced gene expression in epithelial cells transfected with amino acid-substituted gemini nanoparticles.

    PubMed

    Yang, Peng; Singh, Jagbir; Wettig, Shawn; Foldvari, Marianna; Verrall, Ronald E; Badea, Ildiko

    2010-08-01

    Gemini surfactants are versatile gene delivery agents because of their ability to bind and compact DNA and their low cellular toxicity. Through modification of the alkyl tail length and the chemical nature of the spacer, new compounds can be generated with the potential to improve the efficiency of gene delivery. Amino acid (glycine and lysine) and dipeptide (glycyl-lysine and lysyl-lysine) substituted spacers of gemini surfactants were synthesized, and their efficiency of gene delivery was assessed in epithelial cells for topical cutaneous and mucosal applications. Three different epithelial cell lines, COS-7, PAM212 and Sf 1Ep cells, were transfected with plasmid DNA encoding for interferon gamma and green fluorescent protein complexed with the amino acid-substituted gemini compounds in the presence of 1,2 dioleyl-sn-glycero-phosphatidyl-ethanolamine as a helper lipid. Gene expression was quantified by ELISA. Size, zeta potential and circular dichroism measurements were used to characterize the plasmid-gemini (PG) and plasmid-gemini surfactant-helper lipid (PGL) complexes. Gene expression was found to increase up to 72h and then declined by the 7th day. In general, the glycine-substituted surfactant showed consistently high gene expression in all three cell lines. Results of physicochemical and spectroscopic studies of the complexes indicate that substitution of the gemini spacer does not interfere with compaction of the DNA. The superior performance of these spacer-substituted gemini surfactants might be attributed to their better biocompatibility compared to the surfactants possessing unsubstituted spacers.

  4. Cationic Gemini surfactant at the air/water interface.

    PubMed

    Qibin, Chen; Xiaodong, Liang; Shaolei, Wang; Shouhong, Xu; Honglai, Liu; Ying, Hu

    2007-10-15

    The surface properties and structures of a cationic Gemini surfactant with a rigid spacer, p-xylyl-bis(dimethyloctadecylammonium bromide) ([C(18)H(37)(CH(3))(2)N(+)CH(2)C(6)H(4)CH(2)N(+)(CH(3))(2)C(18)H(37)],2Br(-), abbreviated as 18-Ar-18,2Br(-1)), at the air/water interface were investigated. It is found that the surface pressure-molecular area isotherms observed at different temperatures do not exhibit a plateau region but display an unusual "kink" before collapse. The range of the corresponding minimum compressibility and maximum compressibility modulus indicates that the monolayer is in the liquid-expanded state. The monolayers were transferred onto mica and quartz plates by the Langmuir-Blodgett (LB) technique. The structures of monolayers at various surface pressures were studied by atomic force microscopy (AFM) and UV-vis spectroscopy, respectively. AFM measurements show that at lower surface pressures, unlike the structures of complex or hybrid films formed by Gemini amphiphiles with DNA, dye, or inorganic materials or the Langmuir film formed by the nonionic Gemini surfactant, in this case network-like labyrinthine interconnected ridges are formed. The formation of the structures can be interpreted in terms of the spinodal decomposition mechanism. With the increase of the surface pressure up to 35 mN/m, surface micelles dispersed in the network-like ridges gradually appear which might be caused by both the spinodal decomposition and dewetting. The UV-vis adsorption shows that over the whole range of surface pressures, the molecules form a J-aggregate in LB films, which implies that the spacers construct a pi-pi aromatic stacking. This pi-pi interaction between spacers and the van der Waals interaction between hydrophobic chains lead to the formation of both networks and micelles. The labyrinthine interconnected ridges are formed first because of the rapid evaporation of solvent during the spreading processes; with increasing surface pressure, some of the

  5. The Gemini Science User Support Department: A community-centered approach to user support

    NASA Astrophysics Data System (ADS)

    Chené, André-Nicolas; Thomas-Osip, Joanna

    2016-01-01

    The Gemini Science User Support Department (SUSD) was formed a little more than a year ago to create a collaborative community of users and staff and to consolidate existing post-observing support throughout the observatory for more efficient use of resources as well as better visibility amongst our user community. This poster is an opportunity to exchange ideas about how Gemini can improve your experience while working with the Observatory and present details about new avenues of post-observing support coming soon. We encourage your feedback at any time.Shortly after its creation, the SUSD conducted a complete revision of the communication cycle between Gemini and its community of researchers. The cycle was then revisited from the perspective of an astronomer interested in using Gemini for their research. This exercise led to a series of proposed changes that are currently under development, and the implementation of a sub-selection is expected in 2016, including the following. (1) Email notifications: Gemini users will receive new forms of email communications that are more instructive and tailored to their program. The objective is to direct the users more efficiently toward the useful links and documentation all along the lifecycle of the program, from phaseII to after the data are completely reduced. (2) HelpDesk system: The HelpDesk will become more user-friendly and transparent. (3) Webpages: The organization of the Gemini webpages will be redesigned to optimize navigation; especially for anything regarding more critical periods likes phaseIs and phaseIIs. (4) Data Reduction User Forum: Following recommendations from Gemini users, new capabilities were added to the forum, like email notifications, and a voting system, in order to make it more practical. This forum's objective is to bring the Gemini community together to exchange their ideas, thoughts, questions and solutions about data reduction, a sort of Reddit, StackOverflow or Slashdot for Gemini data.

  6. Modelling of the Critical Micelle Concentration of Cationic Gemini Surfactants Using Molecular Connectivity Indices.

    PubMed

    Mozrzymas, Anna

    2013-01-01

    Modelling of the critical micelle concentrations (cmc) using the molecular connectivity indices was performed for a set of 21 cationic gemini surfactants with medium-length spacers. The obtained model contains only the second-order Kier and Hall molecular connectivity index. It is suggested that the index (2)χ includes some information about flexibility. The obtained model was used to predict log10 cmc of other cationic gemini surfactants. The agreement between calculated and experimental values of log10 cmc for the gemini surfactants that were not used in the correlation is very good.

  7. Near-infrared Integral-Field Spectrograph (NIFS): An Instrument Proposed for Gemini

    NASA Astrophysics Data System (ADS)

    McGregor, Peter J.; Conroy, Peter; Bloxham, Gabe; van Harmelen, Jan

    1999-12-01

    In late 1998 the International Gemini Project Office identified a need for a low cost, near-infrared spectrograph to be commissioned on the Gemini South telescope on the shortest possible timescale. In response, the Research School of Astronomy and Astrophysics of the Australian National University proposed to design, construct, and commission a near-infrared, integral-field spectrograph on Gemini. The science drivers and novel design of the Near-infrared Integral-Field Spectrograph (NIFS) are described in this paper. NIFS will achieve significant economies in cost and schedule in several ways:

  8. The Gemini Planet Imager Calibration Wavefront Sensor Instrument

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Burruss, Rick S.; Bartos, Randall D.; Trinh, Thang Q.; Pueyo, Laurent A.; Fregoso, Santos F.; Angione, John R.; Shelton, J. Chris

    2010-01-01

    The Gemini Planet Imager is an extreme adaptive optics system that will employ an apodized-pupil coronagraph to make direct detections of faint companions of nearby stars to a contrast level of the 10(exp -7) within a few lambda/D of the parent star. Such high contrasts from the ground require exquisite wavefront sensing and control both for the AO system as well as for the coronagraph. Un-sensed non-common path phase and amplitude errors after the wavefront sensor dichroic but before the coronagraph would lead to speckles which would ultimately limit the contrast. The calibration wavefront system for GPI will measure the complex wavefront at the system pupil before the apodizer and provide slow phase corrections to the AO system to mitigate errors that would cause a loss in contrast. The calibration wavefront sensor instrument for GPI has been built. We will describe the instrument and its performance.

  9. Experiment T001: Entry communication on the Gemini 3 mission

    NASA Technical Reports Server (NTRS)

    Schroeder, L. C.; Sims, T. E.; Cuddihy, W. F.

    1971-01-01

    Water addition to the Gemini 3 exhaust plasma was studied to determine its effectiveness in the establishment of communication links during the entry portion of the flight. Attenuation levels were measured with and without water injection at uhf frequencies of 230.4 and 296.8 megahertz and at the C-band frequency of 5690 megahertz. Ultrahigh frequency signals that had been blacked out were restored to significant levels, during early portions of the water-injection sequence, by the high flow rate injection. The C-band signal was enhanced by medium and high flow rate injections during the latter portion of the injection period. The uhf signal recovered during water injection resulted in an antenna pattern that was beamed in the radial direction of injection from the spacecraft. Postflight analysis showed that the uhf recovery data were consistent with injection-penetration theory.

  10. Fan-In Communications On A Cray Gemini Interconnect

    SciTech Connect

    Jones, Terry R; Settlemyer, Bradley W

    2014-01-01

    Using the Cray Gemini interconnect as our platform, we present a study of an important class of communication operations the fan-in communication pattern. By its nature, fan-in communications form hot spots that present significant challenges for any interconnect fabric and communication software stack. Yet despite the inherent challenges, these communication patterns are common in both applications (which often perform reductions and other collective operations that include fan-in communication such as barriers) and system software (where they assume an important role within parallel file systems and other components requiring high-bandwidth or low-latency I/O). Our study determines the effectiveness of differing clientserver fan-in strategies. We describe fan-in performance in terms of aggregate bandwidth in the presence of varying degrees of congestion, as well as several other key attributes. Comparison numbers are presented for the Cray Aries interconnect. Finally, we provide recommended communication strategies based on our findings.

  11. Gemini 8.2-m primary mirror no. 1 polishing

    NASA Astrophysics Data System (ADS)

    Cayrel, Marc; Beraud, P.; Paseri, Jacques; Dromas, E.

    1998-08-01

    The 8-m class primary mirrors of the GEMINI Telescopes are thin ULE menisci actively supported. The two mirror blanks are produced by CORNING, the optical figuring, manufacturing and assembling of interfaces are done by REOSC. REOSC is as well in charge of the transportation of the mirror blanks from CORNING to REOSC, and of the shipment of the finished optics to Hawaii and to Chile. The mirror assembly requirements are summarized, the manufacturing and testing methods are addressed. REOSC had to design and manufacture a dedicated active supporting system, representative of the one used at the telescope level. Its design and performance are presented. The manufacturing steps undertaken at REOSC and the results achieved are then detailed: mirror blank surface generating and grinding, polishing, testing. The current status of the mirrors is finally presented.

  12. Gemini: Extending Information Management for Real Time Tactical Environments

    DTIC Science & Technology

    2008-03-01

    access to multiple other aircraft and the  Global  Information Grid (GIG). On these  UAS, Gemini may be installed in the form of a small payload or onto an...There are several technologies specifically designed for compressing XML data (for example XGrind,  XML‐ Xpress , and XMill). A general purpose...Future Force Warrior (US Army)  GIG  Global  Information Grid  GNOME  GNU Object Model Environment  GNU  GNU’s Not Unix  IDL  Interface Definition

  13. The Gemini MCAO infrastructure: laser service enclosure and support structure

    NASA Astrophysics Data System (ADS)

    Cavedoni, Charles P.; Bombino, S.; Sheehan, M.; Karewicz, S.; Hardash, S.; Perez, G.; Collins, P.; d'Orgeville, C.; Boccas, M.; Maltes, D.; Gausachs, G.; Rogers, R.

    2008-07-01

    The Laser Service Enclosure (LSE) is an environmentally controlled ISO 7 clean room designed to house, protect and provide environmental control for the Gemini South multi-conjugate adaptive optics laser system. The LSE is 8.0 meters long, 2.5 meters wide and 2.5 meters high with a mass of approximately 5,100 kg. The LSE shall reside on a new telescope Nasmyth platform named the Support Structure (SS). The SS is a three-dimensional beam and frame structure designed to support the LSE and laser system under all loading conditions. This paper will review the system requirements and describe the system hardware including optical, environmental, structural and operational issues as well as the anticipated impact the system will have on the current telescope performance.

  14. Management aspects of Gemini's base facility operations project

    NASA Astrophysics Data System (ADS)

    Arriagada, Gustavo; Nitta, Atsuko; Adamson, A. J.; Nunez, Arturo; Serio, Andrew; Cordova, Martin

    2016-08-01

    Gemini's Base Facilities Operations (BFO) Project provided the capabilities to perform routine nighttime operations without anyone on the summit. The expected benefits were to achieve money savings and to become an enabler of the future development of remote operations. The project was executed using a tailored version of Prince2 project management methodology. It was schedule driven and managing it demanded flexibility and creativity to produce what was needed, taking into consideration all the constraints present at the time: Time available to implement BFO at Gemini North (GN), two years. The project had to be done in a matrix resources environment. There were only three resources assigned exclusively to BFO. The implementation of new capabilities had to be done without disrupting operations. And we needed to succeed, introducing the new operational model that implied Telescope and instrumentation Operators (Science Operations Specialists - SOS) relying on technology to assess summit conditions. To meet schedule we created a large number of concurrent smaller projects called Work Packages (WP). To be reassured that we would successfully implement BFO, we initially spent a good portion of time and effort, collecting and learning about user's needs. This was done through close interaction with SOSs, Observers, Engineers and Technicians. Once we had a clear understanding of the requirements, we took the approach of implementing the "bare minimum" necessary technology that would meet them and that would be maintainable in the long term. Another key element was the introduction of the "gradual descent" concept. In this, we increasingly provided tools to the SOSs and Observers to prevent them from going outside the control room during nighttime operations, giving them the opportunity of familiarizing themselves with the new tools over a time span of several months. Also, by using these tools at an early stage, Engineers and Technicians had more time for debugging

  15. Gemini ester quat surfactants and their biological activity.

    PubMed

    Łuczyński, Jacek; Frąckowiak, Renata; Włoch, Aleksandra; Kleszczyńska, Halina; Witek, Stanisław

    2013-03-01

    Cationic gemini surfactants are an important class of surface-active compounds that exhibit much higher surface activity than their monomeric counterparts. This type of compound architecture lends itself to the compound being easily adsorbed at interfaces and interacting with the cellular membranes of microorganisms. Conventional cationic surfactants have high chemical stability but poor chemical and biological degradability. One of the main approaches to the design of readily biodegradable and environmentally friendly surfactants involves inserting a bond with limited stability into the surfactant molecule to give a cleavable surfactant. The best-known example of such a compound is the family of ester quats, which are cationic surfactants with a labile ester bond inserted into the molecule. As part of this study, a series of gemini ester quat surfactants were synthesized and assayed for their biological activity. Their hemolytic activity and changes in the fluidity and packing order of the lipid polar heads were used as the measures of their biological activity. A clear correlation between the hemolytic activity of the tested compounds and their alkyl chain length was established. It was found that the compounds with a long hydrocarbon chain showed higher activity. Moreover, the compounds with greater spacing between their alkyl chains were more active. This proves that they incorporate more easily into the lipid bilayer of the erythrocyte membrane and affect its properties to a greater extent. A better understanding of the process of cell lysis by surfactants and of their biological activity may assist in developing surfactants with enhanced selectivity and in widening their range of application.

  16. Coacervation with surfactants: From single-chain surfactants to gemini surfactants.

    PubMed

    Zhao, Weiwei; Wang, Yilin

    2017-01-01

    Coacervation is a spontaneous process during which a colloidal dispersion separates into two immiscible liquid phases: a colloid-rich liquid phase in equilibrium with a diluted phase. Coacervation is usually divided into simple coacervation and complex coacervation according to the number of components. Surfactant-based coacervation normally contains traditional single-chain surfactants. With the development of surfactants, gemini surfactants with two amphiphilic moieties have been applied to form coacervation. This review summarizes the development of simple coacervation and complex coacervation in the systems of single-chain surfactants and gemini surfactants. Simple coacervation in surfactant solutions with additives or at elevated temperature and complex coacervation in surfactant/polymer mixtures by changing charge densities, molecular weight, ionic strength, pH, or temperature are reviewed. The comparison between gemini surfactants and corresponding monomeric single-chain surfactants reveals that the unique structures of gemini surfactants endow them with higher propensity to generate coacervation.

  17. Interactions between DNA and Gemini surfactant: impact on gene therapy: part I.

    PubMed

    Ahmed, Taksim; Kamel, Amany O; Wettig, Shawn D

    2016-02-01

    Nonviral gene therapy using gemini surfactants is a unique approach to medicine that can be adapted toward the treatment of various diseases. Recently, gemini surfactants have been utilized as candidates for the formation of nonviral vectors. The chemical structure of the surfactant (variations in the alkyl tail length and spacer/head group) and the resulting physicochemical properties of the lipoplexes are critical parameters for efficient gene transfection. Moreover, studying the interaction of the surfactant with DNA can help in designing an efficient vector and understanding how transfection complexes overcome various cellular barriers. Part I of this review provides an overview of various types of gemini surfactants designed for gene therapy and their transfection efficiency; and Part II will focus on different novel methods utilized to understand the interactions between the gemini and DNA in a lipoplex.

  18. Synthesis and crystal structures of gold nanowires with Gemini surfactants as directing agents.

    PubMed

    Xu, Feng; Hou, Hao; Gao, Zhinong

    2014-12-15

    The preparation of crystalline gold nanowires (NWs) by using gemini surfactants as directing agents through a three-step seed-mediated method is reported. Unlike the nanorods with relatively low aspect ratios (typically below 20) obtained by using cetyltrimethylammonium bromide as a directing agent, the NWs obtained in this investigation can reach up to 4.4 μm, and the largest aspect ratio is calculated to be 210. For this, each of seven different gemini surfactants are utilized as directing agents, and the length and/or aspect ratio of the NWs can be tuned by varying the hydrocarbon chain lengths of the gemini surfactants. Both single and twinned crystalline structures are elucidated by selected-area electron diffraction and high-resolution transmission electron microscopy studies. The use of gemini surfactants not only advances the synthesis of gold nanostructures, but improves the understanding of the growth mechanism for seed-mediated growth.

  19. Gemini 12 crew receive Official welcome aboard U.S.S. Wasp

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronauts James A. Lovell Jr. (left), command pilot, and Edwin E. Aldrin Jr., pilot, receive Official welcome as they arrive aboard the aircraft carrier U.S.S. Wasp after their splashdown at the end of the Gemini 12 mission.

  20. Structure-activity investigation on the gene transfection properties of cardiolipin mimicking gemini lipid analogues.

    PubMed

    Bajaj, Avinash; Paul, Bishwajit; Kondaiah, Paturu; Bhattacharya, Santanu

    2008-06-01

    A structure-activity relationship has been explored on the gene transfection efficiencies of cardiolipin mimicking gemini lipid analogues upon variation of length and hydrophilicity of the spacer between the cationic ammonium headgroups and lipid hydrocarbon chain lengths. All the gemini lipids were found to be highly superior in gene transfer abilities as compared to their monomeric lipid and a related commercially available formulation. Pseudoglyceryl gemini lipids bearing an oxyethylene (-CH2-(CH2-O-CH2)m-CH2-) spacer were found to be superior gene transfecting agents as compared to those bearing polymethylene (-CH2)m-) spacers. The major characteristic feature of the present set of gemini lipids is their serum compatibility, which is most often the major hurdle in liposome-mediated gene delivery.

  1. Astronaut John Young waits for pickup by helicopter after Gemini 3 landing

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronaut John W. Young, pilot of the Gemini-Titan 3 flight, sits in a life raft waiting to be picked up by helicopter during recovery operations following the landing. Navy swimmers can be seen assisting in the recovery operations.

  2. Molecular connectivity indices for modeling the critical micelle concentration of cationic (chloride) Gemini surfactants.

    PubMed

    Mozrzymas, Anna

    2017-01-01

    The molecular connectivity indices were used to derive the simple model relating the critical micelle concentration of cationic (chloride) gemini surfactants to their structure. One index was selected as the best to describe the effect of the structure of investigated compounds on critical micelle concentration consistent with the experimental results. This index encodes the information about molecular size, the branches, and also the information about heteroatoms. The selected model can be helpful in designing novel chloride gemini surfactants.

  3. The Near-Earth Encounter of 2005 YU55: Thermal Infrared Observations from Gemini North

    NASA Technical Reports Server (NTRS)

    Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.; Granvik, Mikael

    2012-01-01

    As part of a multi-observatory campaign to observe 2005 YU55 during its November 2011 encounter with the Earth, thermal infrared photometry and spectroscopy (7.9- 14 and 18-22 micron) were conducted using the Michelle instrument at Gemini North. Reduction of the 8.8 flm photometry and the spectroscopy from UT Nov-IO as well as of all the Gemini data from UT Nov-9 is in progress. Results will be discussed.

  4. Target of Opportunity Observing in Queue Mode at the Gemini North Observatory

    NASA Astrophysics Data System (ADS)

    Roth, Katherine; Price, P.; Gillies, K.; Walker, S.; Miller, B.

    2009-01-01

    The Gemini Observatories primarily operate a multi-instrument queue, with observers selecting observations that are best suited to weather and seeing conditions. Queue operations give higher ranked programs a greater chance for completion than lower ranked programs requesting the same conditions and instrument configuration. Queue observing naturally lends itself to Target of Opportunity (ToO) support since the time required to switch between programs and instruments is very short, and the staff observer is trained to operate all the available instruments and modes. Gemini Observatory has supported pre-approved ToO programs since beginning queue operations, and has implemented a rapid (less than 15 minutes response time) ToO mode since 2005. The rapid response ToO mode has thus far been exclusively utilized by the Gemini community for optical and near-IR follow-up of Gamma Ray Bursts (GRBs), primarily discovered by the Swift satellite. We discuss the ToO implementation at Gemini Observatory including the ToO user interface and the procedures followed by observatory staff astronomers once a ToO trigger is received. We present the statistics of 4 years of rapid ToOs at Gemini North Observatory, and the advances in our understanding of GRBs, their host galaxies and the intergalactic medium that this important mode has enabled. Finally we discuss recent changes in both software and policy to improve standard and rapid ToO support at the Gemini Observatories. The Gemini Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciìncia e Tecnologia (Brazil), and SECYT (Argentina)

  5. Mixed micellization of gemini and conventional surfactant in aqueous solution: a lattice Monte Carlo simulation.

    PubMed

    Gharibi, Hussein; Khodadadi, Zahra; Mousavi-Khoshdel, S Morteza; Hashemianzadeh, S Majid; Javadian, Soheila

    2014-09-01

    In the current study, we have investigated the micellization of pure gemini surfactants and a mixture of gemini and conventional surfactants using a 3D lattice Monte Carlo simulation method. For the pure gemini surfactant system, the effects of tail length on CMC and aggregation number were studied, and the simulation results were found to be in excellent agreement with the experimental results. For a mixture of gemini and conventional surfactants, variations in the mixed CMC, interaction parameter β, and excess Gibbs free energy G(E) with composition revealed synergism in micelle formation. Simulation results were compared to estimations made using regular solution theory to determine the applicability of this theory for non-ideal mixed surfactant systems. A large discrepancy was observed between the behavior of parameters such as the activity coefficients fi and the excess Gibbs free energy G(E) and the expected behavior of these parameters as predicted by regular solution theory. Therefore, we have used the modified version of regular solution theory. This three parameter model contains two parameters in addition to the interaction parameters: the size parameter, ρ, which reflects differences in the size of components, and the packing parameter, P*, which reflects nonrandom mixing in mixed micelles. The proposed model provides a good description of the behavior of gemini and conventional surfactant mixtures. The results indicated that as the chain length of gemini surfactants in mixture is increased, the size parameter remains constant while the interaction and packing parameters increase.

  6. Mixed aggregate formation in gemini surfactant/1,2-dialkyl-sn-glycero-3-phosphoethanolamine systems.

    PubMed

    Akbar, Javed; Tavakoli, Naser; Marangoni, D Gerrard; Wettig, Shawn D

    2012-07-01

    An evaluation of the physical interactions between gemini surfactants, DNA, and 1,2-dialkyl-sn-glycero-3-phosphoethanolamine helper lipid is presented in this work. Complexation between gemini surfactants and DNA was first investigated using surface tensiometry where the surface tension profiles obtained were found to be consistent with those typically observed for mixed surfactant-polymer systems; that is, there is a synergistic lowering of the surface tension, followed by a first (CAC) and second (CMC) break point in the plot. The surfactant alkyl tail length was observed to exhibit a significant effect on the CAC, thus demonstrating the importance of hydrophobic interactions during complexation between gemini surfactants and DNA. The second study presented is an investigation of the mixing interactions between gemini surfactants and DOPE using Clint's, Rubingh's, and Motomura's theories for mixed micellar formation. The mixing interactions between the 16-3-16/16-7-16/16-12-16/16-7NH-16 gemini surfactants and DOPE were observed to be antagonistic, where the strength of antagonism was found to be dependent upon the gemini surfactant spacer group and the solution composition.

  7. Hierarchical Structure from the Self-Assembly of Giant Gemini Surfactants in Condensed State

    NASA Astrophysics Data System (ADS)

    Su, Hao; Wang, Zhao; Li, Yiwen; Cheng, Stephen

    2013-03-01

    In the past a few years, a new class of amphiphiles with both asymmetrical shapes and interactions named ``shape amphiphiles'' has been significantly intensified. Recently, a new kind of shape amphiphiles called ``Giant Gemini Surfactants'' consisting of two hydrophilic carboxylic acid-functionalized polyhedral oligomeric silsesquioxane (APOSS) heads and two hydrophobic polystyrene (PS) tails covalently linked via rigid spacers (p-phenylene versus biphenylene) has been successful behavior of giant gemini surfactants. We currently continue to investigate the spacer effects on the self-assembly behaviors of giant gemini surfactants in condensed state by utilizing DCS, SAXS and TEM. Preliminary results showed that giant gemini surfactants with different spacers have diverse phase behaviors. As we use the same 3.2k PS chains, the giant gemini surfactant with p-phenylene spacer showed double gyroid morphology, while the one with biphenylene spacer revealed cylindrical morphology. This study expands the scope of giant gemini surfactants and contributes a lot to the basic physical principles in self-assembly behavior.

  8. Role of spacer lengths of gemini surfactants in the synthesis of silver nanorods in micellar media.

    PubMed

    Bhattacharya, Santanu; Biswas, Joydeep

    2011-07-01

    In this work, we have prepared Ag-nanorods using biscationic gemini surfactant micelles as the media by a seed-mediated wet synthesis method. Towards this end, we first synthesized Ag-nanoseeds of diameter ~7 nm stabilized by trisodium citrate (as the capping agent). Then these Ag-nanoseeds were used to synthesize Ag-nanorods of different aspect ratios. With decreasing Ag-nanoseed concentration, the aspect ratios of the Ag-nanorods stabilized by these gemini surfactants increased gradually. Various Ag-nanoseeds and Ag-nanospecies were characterized using UV-Vis spectroscopy (to know the surface plasmon bands), transmission electron microscopy (to find out their particle sizes and distribution), energy-dispersive X-ray spectroscopy and X-ray diffraction. When we used micelles derived from gemini surfactants of shorter spacer -(CH(2))(n)- (n = 2 or 4) to stabilize the Ag-nanorods, the λ(max) of the longitudinal band shifted more towards the blue region compared to that of the gemini surfactant micelles with a longer spacer -(CH(2))(n)- (n = 5, 12) at a given amount of the Ag-nanoseed solution. So, the growth of Ag-nanorods in the gemini micellar solutions depends on the spacer-chain length of gemini surfactants employed.

  9. Synthesis and aggregation properties of dissymmetric phytanyl-gemini surfactants for use as improved DNA transfection vectors.

    PubMed

    Wang, Haitang; Wettig, Shawn D

    2011-01-14

    Improvements in transfection efficiency are required in order to make the goal of cellular gene delivery by non-viral vectors realizable. Novel derivatives of gemini surfactants having dissymmetric tail groups have been designed specifically as a means to improve DNA transfection; the micelle and interfacial properties are reported herein. The effect of these substitutions on the aggregation properties of the gemini surfactants is discussed in the context of results for the m-3-m gemini series, previously reported in the literature. Phytanyl substitution results in lower cmc and higher micelle ionization. In addition, the phytanyl substituted gemini surfactants form vesicles at room temperature. Preliminary in vitro transfection assays showed the phytanyl substituted gemini surfactants to be more efficient transfection vectors as compared to symmetric gemini surfactants.

  10. Misión de operaciones en ambientes extremos

    NASA Video Gallery

    ¿En qué lugar del planeta se puede entrenar un astronauta en un entorno similar al espacio? ¿Qué les parece bajo el agua? NEEMO es un proyecto que envía a grupos de astronautas, ingenieros, médicos...

  11. Properties of Ellipticity Correlation with Atmospheric Structure from Gemini South

    SciTech Connect

    Asztalos, S J; Treadway, T; de Vries, W H; Rosenberg, L J; Burke, D; Claver, C; Saha, A; Puxley, P

    2006-12-21

    Cosmic shear holds great promise for a precision independent measurement of {Omega}{sub m}, the mass density of the universe relative to the critical density. The signal is expected to be weak, so a thorough understanding of systematic effects is crucial. An important systematic effect is the atmosphere: shear power introduced by the atmosphere is larger than the expected signal. Algorithms exist to extract the cosmic shear from the atmospheric component, though a measure of their success applied to a range of seeing conditions is lacking. To gain insight into atmospheric shear, Gemini South imaging in conjunction with ground condition and satellite wind data were obtained. We find that under good seeing conditions Point-Spread-Function (PSF) correlations persist well beyond the separation typical of high-latitude stars. Under these conditions, ellipticity residuals based on a simple PSF interpolation can be reduced to within a factor of a few of the shot-noise induced ellipticity floor. We also find that the ellipticity residuals are highly correlated with wind direction. Finally, we correct stellar shapes using a more sophisticated procedure and generate shear statistics from stars. Under all seeing conditions in our data set the residual correlations lie everywhere below the target signal level. For good seeing we find that the systematic error attributable to atmospheric turbulence is comparable in magnitude to the statistical error (shape noise) over angular scales relevant to present lensing surveys.

  12. Properties of Ellipticity Correlation with Atmospheric Structure From Gemini South

    SciTech Connect

    Asztalos, Stephen J.; de Vries, W.H.; Rosenberg, L.J; Treadway, T.; Burke, D.; Claver, C.; Saha, A.; Puxley, P.; /Gemini Observ., La Serena

    2007-01-17

    Cosmic shear holds great promise for a precision independent measurement of {Omega}{sub m}, the mass density of the universe relative to the critical density. The signal is expected to be weak, so a thorough understanding of systematic effects is crucial. An important systematic effect is the atmosphere: shear power introduced by the atmosphere is larger than the expected signal. Algorithms exist to extract the cosmic shear from the atmospheric component, though a measure of their success applied to a range of seeing conditions is lacking. To gain insight into atmospheric shear, Gemini South imaging in conjunction with ground condition and satellite wind data were obtained. We find that under good seeing conditions Point-Spread-Function (PSF) correlations persist well beyond the separation typical of high-latitude stars. Under these conditions, ellipticity residuals based on a simple PSF interpolation can be reduced to within a factor of a few of the shot-noise induced ellipticity floor. We also find that the ellipticity residuals are highly correlated with wind direction. Finally, we correct stellar shapes using a more sophisticated procedure and generate shear statistics from stars. Under all seeing conditions in our data set the residual correlations lie everywhere below the target signal level. For good seeing we find that the systematic error attributable to atmospheric turbulence is comparable in magnitude to the statistical error (shape noise) over angular scales relevant to present lensing surveys.

  13. The Gemini Planet Imager Exoplanet Survey (GPIES) Campaign Initial Results

    NASA Astrophysics Data System (ADS)

    Patience, Jennifer; Macintosh, Bruce; Graham, James R.; Barman, Travis; De Rosa, Robert; Konopacky, Quinn; Marley, Mark; Marois, Christian; Nielsen, Eric Ludwig; Pueyo, Laurent; Rajan, Abhijith; Rameau, Julien; Saumon, Didier; Wang, Jason

    2015-12-01

    The Gemini Planet Imager (GPI) is a next-generation coronagraphic integral field unit with the sensitivity and resolution to detect planetary companions with separations of 0”.2 to 1”.0 around a large set of stars. An 890-hour GPI survey of 600 young, nearby stars commenced in late-2014, and approximately 100 stars have been observed thus far. The central aims of the program are: (1) the discovery of a population of giant planets with orbital radii of 5-50 AU comparable to Solar System gas giant orbits, (2) the characterization of the atmospheric properties of young planetary companions, and (3) the exploration of planet-disk interactions. Initial results from GPI exoplanet observations include the discovery of a new planetary companion to a young F-star; the planet spectrum shows a strong signature of methane absorption, indicating a cooler temperature than previously imaged young planets. An overview of the survey scope, current detection limits, and initial results will be presented.

  14. Gemini/GRACES spectroscopy of stars in Tri II

    NASA Astrophysics Data System (ADS)

    Venn, K. A.; Starkenburg, E.; Malo, L.; Martin, N.; Laevens, B. P. M.

    2017-04-01

    The chemical abundance ratios and radial velocities for two stars in the recently discovered Triangulum II faint dwarf galaxy have been determined from high-resolution, medium signal-to-noise ratio spectra from the Gemini Remote Access to CFHT ESPaDonS Spectrograph facility. These stars have stellar parameters and metallicities similar to those derived from their photometry and medium-resolution Ca II triplet spectra, and supports that Triangulum II has a metallicity spread consistent with chemical evolution in a dwarf galaxy. The elemental abundances show that both stars have typical calcium abundances and barium upper limits for their metallicities, but low magnesium and sodium. This chemical composition resembles some stars in dwarf galaxies, attributed to inhomogeneous mixing in a low star formation environment, and/or yields from only a few supernova events. One of our targets (Star40) has an enhancement in potassium, and resembles some stars in the unusual outer halo star cluster, NGC 2419. Our other target (Star46) appears to be a binary based on a change in its radial velocity (Δvrad = 24.5 ±2.1 km s-1). This is consistent with variations found in binary stars in other dwarf galaxies. While this serves as a reminder of the high binary fraction in these ultrafaint dwarf galaxies, this particular object has had little impact on the previous determination of the velocity dispersion in Triangulum II.

  15. Anionic Gemini Surfactants:. Synthesis and Surface Active Properties

    NASA Astrophysics Data System (ADS)

    Shukla, Dipti; Tyagi, V. K.

    New compounds bearing two phosphate groups and two long chain (dodecyl) were prepared by two-step reaction: (i) phosphorylation of dodecanol with pyrophosphoric acid, (ii) reaction of dodecyl phosphate with N(CH3)4OH and 1,6-dibromo hexane. The effect of reaction variables like time and molar ratio of reactants on yield has also been reported. The 1:2:0.5 molar ratio of reactants (dodecyl phosphate, N(CH3)4OH, and Br(CH2)6 Br, respectively) and 3 h duration resulted to give maximum yield of anionic gemini surfactants. The structure of synthesized surfactant was investigated by modern analytical techniques, viz. FT-IR, 1H NMR, 13C NMR. Amphipathic disodium phosphates were obtained by neutralization of free acids with sodium hydroxide and their surface active properties in aqueous solution were measured. These disodium phosphates possessed 77.3% anionic content and showed good water solubility. Foaming properties and wetting ability were also evaluated.

  16. Results from the Gemini NICI Planet-Finding Campaign

    NASA Astrophysics Data System (ADS)

    Biller, Beth A.; Liu, Michael C.; Wahhaj, Zahed; Nielsen, Eric L.; Hayward, Thomas L.; Chun, Mark R.; Close, Laird M.; Ftaclas, Christ; Males, Jared R.; Hartung, Markus; Reid, I. N.; Shkolnik, Evgenya; Skemer, Andrew J.; Tecza, Matthias; Thatte, Niranjan A.; Clarke, Fraser; Toomey, Douglas

    2014-08-01

    From 2008 December to 2012 September, the NICI (Near-Infrared Coronagraphic Imager at the Gemini-South 8.1-m) Planet-Finding Campaign (Liu et al. 2010) obtained deep, high-contrast AO imaging of a carefully selected sample of over 200 young, nearby stars. In the course of the campaign, we discovered four co-moving brown dwarf companions: PZ Tel B (36+/-6 MJup, 16.4+/-1.0 AU), CD-35 2722B (31+/-8 MJup, 67+/-4 AU), HD 1160B (33+12 -9 MJup, 81+/- AU), and HIP 79797Bb (55+20-19MJup, 3 AU from the previously known brown dwarf companion HIP 79797Ba), as well as numerous stellar binaries. Three survey papers have been published to date, covering: 1) high mass stars (Nielsen et al. 2013), 2) debris disk stars (Wahhaj et al. 2013), and 3) stars which are members of nearby young moving groups (Biller et al. 2013). In addition, the Campaign has yielded new orbital constraints for the ~8-10 MJup planet Pic β (Nielsen et al. 2014) and a high precision measurement of the star-disk offset for the well-known disk around HR 4796A (Wahhaj et al. 2014). Here we discuss constraints placed on the distribution of wide giant exoplanets from the NICI Campaign, new substellar companion discoveries, and characterization both of exoplanets and circumstellar disks.

  17. Gemini planet imager observational calibrations V: astrometry and distortion

    NASA Astrophysics Data System (ADS)

    Konopacky, Quinn M.; Thomas, Sandrine J.; Macintosh, Bruce A.; Dillon, Daren; Sadakuni, Naru; Maire, Jérôme; Fitzgerald, Michael; Hinkley, Sasha; Kalas, Paul; Esposito, Thomas; Marois, Christian; Ingraham, Patrick J.; Marchis, Franck; Perrin, Marshall D.; Graham, James R.; Wang, Jason J.; De Rosa, Robert J.; Morzinski, Katie; Pueyo, Laurent; Chilcote, Jeffrey K.; Larkin, James E.; Fabrycky, Daniel; Goodsell, Stephen J.; Oppenheimer, Ben R.; Patience, Jenny; Saddlemyer, Leslie; Sivaramakrishnan, Anand

    2014-07-01

    We present the results of both laboratory and on sky astrometric characterization of the Gemini Planet Imager (GPI). This characterization includes measurement of the pixel scale* of the integral field spectrograph (IFS), the position of the detector with respect to north, and optical distortion. Two of these three quantities (pixel scale and distortion) were measured in the laboratory using two transparent grids of spots, one with a square pattern and the other with a random pattern. The pixel scale in the laboratory was also estimate using small movements of the artificial star unit (ASU) in the GPI adaptive optics system. On sky, the pixel scale and the north angle are determined using a number of known binary or multiple systems and Solar System objects, a subsample of which had concurrent measurements at Keck Observatory. Our current estimate of the GPI pixel scale is 14.14 +/- 0.01 millarcseconds/pixel, and the north angle is -1.00 +/- 0.03°. Distortion is shown to be small, with an average positional residual of 0.26 pixels over the field of view, and is corrected using a 5th order polynomial. We also present results from Monte Carlo simulations of the GPI Exoplanet Survey (GPIES) assuming GPI achieves ~1 milliarcsecond relative astrometric precision. We find that with this precision, we will be able to constrain the eccentricities of all detected planets, and possibly determine the underlying eccentricity distribution of widely separated Jovians.

  18. Oleic acid-based gemini surfactants with carboxylic acid headgroups.

    PubMed

    Sakai, Kenichi; Umemoto, Naoki; Matsuda, Wataru; Takamatsu, Yuichiro; Matsumoto, Mutsuyoshi; Sakai, Hideki; Abe, Masahiko

    2011-01-01

    Anionic gemini surfactants with carboxylic acid headgroups have been synthesized from oleic acid. The hydrocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via an ester bond, and the carboxylic acid headgroups are introduced to the cis double bond of oleic acid via disuccinyl units. The surfactants exhibit pH-dependent protonation-deprotonation behavior in aqueous solutions. In alkaline solutions (pH 9 in the presence of 10 mmol dm(-3) NaCl as the background electrolyte), the surfactants can lower the surface tension as well as form molecular assemblies, even in the region of low surfactant concentrations. Under acidic (pH 3) or neutral (pH 6-7) conditions, the surfactants are intrinsically insoluble in aqueous media and form a monolayer at the air/water interface. In this study, we have investigated physicochemical properties such as the function of the hydrocarbon chain length by means of static surface tension, pyrene fluorescence, dynamic light scattering, surface pressure-area isotherms, and infrared external reflection measurements.

  19. On the Spacer Group Effect on Critical Micelle Concentration of Cationic Gemini Surfactants Using Molecular Connectivity Indices.

    PubMed

    Mozrzymas, Anna

    2016-01-01

    The important factor which differentiates gemini surfactants from conventional monomeric surfactants is the spacer group. The molecular connectivity method was used to study the effect of the spacer group on critical micelle concentration of cationic gemini surfactants. Two models were derived employing only Kier and Hall molecular connectivity indices. The relationships were developed for a set of 17 gemini surfactants with various spacer groups only. These models can be used to design the structure of the spacer group and in consequence novel cationic gemini surfactants more active in micelle formation.

  20. Antibacterial Activity, in Vitro Cytotoxicity, and Cell Cycle Arrest of Gemini Quaternary Ammonium Surfactants.

    PubMed

    Zhang, Shanshan; Ding, Shiping; Yu, Jing; Chen, Xuerui; Lei, Qunfang; Fang, Wenjun

    2015-11-10

    Twelve gemini quaternary ammonium surfactants have been employed to evaluate the antibacterial activity and in vitro cytotoxicity. The antibacterial effects of the gemini surfactants are performed on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with minimum inhibitory concentrations (MIC) ranging from 2.8 to 167.7 μM. Scanning electron microscopy (SEM) analysis results show that these surfactants interact with the bacterial cell membrane, disrupt the integrity of the membrane, and consequently kill the bacteria. The data recorded on C6 glioma and HEK293 human kidney cell lines using an MTT assay exhibit low half inhibitory concentrations (IC50). The influences of the gemini surfactants on the cell morphology, the cell migration ability, and the cell cycle are observed through hematoxylin-eosin (HE) staining, cell wound healing assay, and flow cytometric analyses, respectively. Both the values of MIC and IC50 decrease against the growth of the alkyl chain length of the gemini surfactants with the same spacer group. In the case of surfactants 12-s-12, the MICs and IC50s are found to decrease slightly with the spacer chain length changing from 2 to 8 and again to increase at higher spacer length (s = 10-12). All of the gemini surfactants show great antibacterial activity and cytotoxicity, and they might exhibit potential applications in medical fields.

  1. Aggregate transitions in aqueous solutions of sodium dodecylsulfate with a "gemini-type" organic salt.

    PubMed

    Yu, Defeng; Tian, Maozhang; Fan, Yaxun; Ji, Gang; Wang, Yilin

    2012-06-07

    Effects of a "gemini-type" organic salt 1,2-bis(2-benzylammoniumethoxy) ethane dichloride (BEO) on the aggregation behavior of sodium dodecylsulfate (SDS) have been investigated by turbidity, surface tension, isothermal titration microcalorimetry, dynamic light scattering, cryogenic transmission electron microscopy, (1)H NMR spectroscopy, and differential scanning microcalorimetry. The aggregation behavior of the SDS/BEO mixed aqueous solution shows strong concentration and ratio dependence. For the SDS/BEO solution with a molar ratio of 5:1, large loose irregular aggregates, vesicles, and long thread-like micelles are formed in succession with the increase of the total SDS and BEO concentration. Because BEO has two positive charges, the SDS/BEO solution may consist of the (SDS)(2)-BEO gemini-type complex, the SDS-BEO complex and extra SDS. The aggregation ability and surface activity of the SDS/BEO mixture exhibit the characteristics of gemini-type surfactants. Along with the results of DSC and (1)H NMR, the (SDS)(2)-BEO gemini-type structure is confirmed to exist in the system. This work provides an approach to construct the surfactant systems with the characteristics of gemini surfactants through intermolecular interaction between a two-charged organic salt and oppositely charged single-chain surfactants.

  2. Self-assembly, DNA binding and cytotoxicity trends of ether functionalized gemini pyridinium amphiphiles.

    PubMed

    Chauhan, Vinay; Singh, Sukhprit; Kamboj, Raman; Mishra, Rachana; Kaur, Gurcharan

    2014-03-01

    Six new ether functionalized gemini pyridinium amphiphiles have been synthesized having dodecyl, tetradecyl alkyl chain lengths and three different spacers (i.e. -(CH2)n-, where n is 4, 5 and 6) and investigated for their self-assembling behavior by state of the art techniques such as tensiometry, conductivity and spectrofluorometry. These new pyridinium gemini surfactants exhibit lower cmc values as compared to other gemini surfactants reported in literature. These amphiphiles form stable complexes with DNA as established by agarose gel electrophoresis and ethidium bromide exclusion experiments. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was carried out in vitro on C6 glioma cell line for cytotoxicity assessment of new pyridinium geminis. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) have been used to measure the micellar size of gemini surfactants. Further, thermal stability of these amphiphiles has been evaluated by thermogravimetric analysis (TGA). The dependence of self-assembly behavior and other properties on spacer as well as alkyl chain length has been established.

  3. Requirements management for Gemini Observatory: a small organization with big development projects

    NASA Astrophysics Data System (ADS)

    Close, Madeline; Serio, Andrew; Cordova, Martin; Hardie, Kayla

    2016-08-01

    Gemini Observatory is an astronomical observatory operating two premier 8m-class telescopes, one in each hemisphere. As an operational facility, a majority of Gemini's resources are spent on operations however the observatory undertakes major development projects as well. Current projects include new facility science instruments, an operational paradigm shift to full remote operations, and new operations tools for planning, configuration and change control. Three years ago, Gemini determined that a specialized requirements management tool was needed. Over the next year, the Gemini Systems Engineering Group investigated several tools, selected one for a trial period and configured it for use. Configuration activities including definition of systems engineering processes, development of a requirements framework, and assignment of project roles to tool roles. Test projects were implemented in the tool. At the conclusion of the trial, the group determined that the Gemini could meet its requirements management needs without use of a specialized requirements management tool, and the group identified a number of lessons learned which are described in the last major section of this paper. These lessons learned include how to conduct an organizational needs analysis prior to pursuing a tool; caveats concerning tool criteria and the selection process; the prerequisites and sequence of activities necessary to achieve an optimum configuration of the tool; the need for adequate staff resources and staff training; and a special note regarding organizations in transition and archiving of requirements.

  4. Synthesis and Monolayer Behaviors of Succinic Acid-Type Gemini Surfactants Containing Semifluoroalkyl Groups.

    PubMed

    Kawase, Tokuzo; Nagase, Youhei; Oida, Tatsuo

    2016-01-01

    In this work, novel succinic acid-type gemini surfactants containing semifluoroalkyl groups, dl- and meso-2,3-bis[Rf-(CH2)n]-succinic acids (Rf = C4F9, C6F13, C8F17; n = 2, 9), were successfully synthesized, and the effects of Rf, methylene chain length (n), and stereochemistry on their monolayer behaviors were studied. Critical micelle concentrations (CMC) of dl- and meso-2,3-bis[C4F9(CH2)9]-succinic acids were one order of magnitude smaller than that of the corresponding 1+1 type surfactant, C4F9(CH2)9COOH. From surface pressure-area (π-A) measurements, the lift-off areas of the geminis were found to decrease in the order C4F9 ≥ C6F13 > C8F17, regardless of methylene chain length and stereochemistry. The zero-pressure molecular areas of the geminis were twice those of the corresponding 1+1 type surfactants. Based on Gibbs compression modulus analysis, it was clarified that 2,3-bis[C8F17(CH2)n]-succinic gemini with short methylene chains (n = 2) would form more rigid monolayers than those having long methylene chains (n = 9). Unlike for 2,3-bis(alkyl)-succinic acids, the effects of stereochemistry on the monolayer behavior of semifluoroalkylated geminis were small.

  5. Solution Properties of Dissymmetric Sulfonate-type Anionic Gemini Surfactants.

    PubMed

    Yoshimura, Tomokazu; Akiba, Kazuki

    2016-01-01

    Dissymmetric and symmetric anionic gemini surfactants, N-alkyl-N'-alkyl-N,N'dipropanesulfonylethylenediamine (CmCnSul, where m and n represent alkyl chain lengths of m-n = 4-16, 6-14, 8-12, 10-10, and 12-12), were synthesized by two- or three-step reactions. Their physicochemical properties were characterized by equilibrium surface tension measurements, steady-state fluorescence spectroscopy of pyrene, and dynamic light scattering. The critical micelle concentration (CMC) of the dissymmetric surfactants C4C16Sul, C6C14Sul, and C8C12Sul was slightly lower than that of the symmetric surfactant C10C10Sul. The occupied area per molecule (A) of C8C12Sul was smaller than that of C10C10Sul, indicating that C8C12Sul has a high surface activity. However, the increase in the degree of dissymmetry from C8C12Sul to C6C14Sul and then to C4C16Sul resulted in high surface tension and large A. Based on the surface tension, the standard free energies of micellization (∆G°mic) and adsorption (∆G°ads), the efficiency of surface adsorption (pC20), and the effectiveness of surface adsorption (CMC/C20) were obtained. These parameters suggested that C8C12Sul formed micelles more readily than the other surfactants. The properties determined from the surface tension indicated that C8C12Sul's ability is intermediate between those of C10C10Sul and C12C12Sul. The pyrene fluorescence and dynamic light scattering results revealed that the micelle size depends on the longer of the two alkyl chains in dissymmetric surfactants.

  6. Ionic Nature of a Gemini Surfactant at the Air/Water Interface.

    PubMed

    Phan, Chi M; Nguyen, Cuong V; Nakahara, Hiromichi; Shibata, Osamu; Nguyen, Thanh V

    2016-12-06

    The ionic state of an adsorbed gemini surfactant at the air/water interface was investigated using a combination of surface potential and surface tension data. The combined model was developed and successfully described the experimental data. The results verified the existence of three ionic states of the gemini surfactant in the interfacial zone. Furthermore, the model can quantify the adsorbed concentrations of these species. At low concentrations, the fully dissociated state dominates the adsorption. At high concentrations, the fully associated state dominates, accounting for up to 80% of the total adsorption. In the middle range, the adsorption is dominated by the partially associated state, which has a maximum percentage of 80% at a critical micelle concentration of 0.5. The variation in the ionic state is a unique characteristic of gemini surfactants, which can be the underlying mechanism for their advantages over conventional surfactants.

  7. A comparison of Gemini and ERTS imagery obtained over southern Morocco

    NASA Technical Reports Server (NTRS)

    Blodget, H. W.; Anderson, A. T.

    1973-01-01

    A mosaic constructed from three ERTS MSS band 5 images enlarged to 1:500,000 compares favorably with a similar scale geologic map of southern Morocco, and a near-similar scale Gemini 5 photo pair. A comparative plot of lineations and generalized geology on the three formats show that a significantly greater number of probable fractures are visible on the ERTS imagery than on the Gemini photography, and that both orbital formats show several times more lineaments than were previously mapped. A plot of mineral occurrences on the structural overlays indicates that definite structure-mineralization relationships exist; this finding is used to define underdeveloped areas which are prospective for mineralization. More detailed mapping is possible using MSS imagery than on Gemini 5 photographs, and in addition, the ERTS format is not restricted to limited coverage.

  8. Differential speckle and wide-field imaging for the Gemini-North and WIYN telescopes

    NASA Astrophysics Data System (ADS)

    Scott, Nicholas J.; Howell, Steve B.; Horch, Elliott P.

    2016-07-01

    Two new instruments are currently being built for the Gemini-North and WIYN telescopes. They are based on the existing DSSI (Differential Speckle Survey Instrument), but the new dual-channel instruments will have both speckle and "wide-field" imaging capabilities. Nearly identical copies of the instrument will be installed as a public access permanent loan at the Gemini-N and WIYN telescopes. Many exoplanet targets will come from the NASA K2 and TESS missions. The faint limiting magnitude, for speckle observations, will remain around 16 to 17th magnitude depending on observing conditions, while wide-field, high speed imaging should be able to go to 21+. For Gemini, the instrument will be remotely operable from either the mid-level facility at Hale Pohaku or the remote operations base in Hilo.

  9. Structural and transfection properties of amine-substituted gemini surfactant-based nanoparticles

    SciTech Connect

    Wettig,S.; Badea, I.; Donkuru, M.; Verrall, R.; Foldvari, M.

    2007-01-01

    Increases in DNA transfection efficiencies for non-viral vectors can be achieved through rational design of novel cationic building blocks. Based on previous results examining DNA condensation by polyamines, novel gemini surfactants have been designed that incorporate aza or imino substituents within the spacer group in order to increase interactions with DNA and potentially improve their DNA transfection ability. Transfection efficiencies and cell toxicity of gemini nanoparticles constructed from plasmid DNA, gemini surfactant, and a neutral lipid were measured in COS7 cells using a luciferase assay. Structural properties of nanoparticles were examined by using circular dichroism, particle size, zeta potential, and small-angle X-ray scattering (SAXS) measurements. The incorporation of aza and imino substituents within the spacer group was observed to enhance the transfection ability of gemini surfactants. Incorporation of an imino group in the structure of the 1,9-bis(dodecyl)-1,1,9,9-tetramethyl-5-imino-1,9-nonanediammonium dibromide surfactant (12-7NH-12) resulted in a statistically significant (p < 0.01) 9-fold increase in transfection compared to an unsubstituted gemini surfactant and a 3-fold increase compared to the corresponding aza-substituted compound. A pH-dependent transition in size and zeta potential was observed to occur at pH 5.5 for complexes formed from the 12-7NH-12 compound. SAXS results show weakly ordered structures and the presence of multiple phases. The incorporation of a pH-active imino group within the spacer of the gemini surfactant results in a significant increase in transfection efficiency that can be related to both pH-induced changes in nanoparticle structure and the formation of multiple phases that more readily allow for membrane fusion that may facilitate DNA release.

  10. Meeting the challenges of bringing a new base facility operation model to Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Nitta, Atsuko; Arriagada, Gustavo; Adamson, A. J.; Cordova, Martin; Nunez, Arturo; Serio, Andrew; Kleinman, Scot

    2016-08-01

    The aim of the Gemini Observatory's Base Facilities Project is to provide the capabilities to perform routine night time operations with both telescopes and their instruments from their respective base facilities without anyone present at the summit. Tightening budget constraints prompted this project as both a means to save money and an opportunity to move toward increasing remote operations in the future. We successfully moved Gemini North nighttime operation to our base facility in Hawaii in Nov., 2015. This is the first 8mclass telescope to completely move night time operations to base facility. We are currently working on implementing BFO to Gemini South. Key challenges for this project include: (1) This is a schedule driven project. We have to implement the new capabilities by the end of 2015 for Gemini North and end of 2016 for Gemini South. (2) The resources are limited and shared with operations which has the higher priority than our project. (3) Managing parallel work within the project. (4) Testing, commissioning and introducing new tools to operational systems without adding significant disruptions to nightly operations. (5) Staff buying to the new operational model. (6) The staff involved in the project are spread on two locations separated by 10,000km, seven time zones away from each other. To overcome these challenges, we applied two principles: "Bare Minimum" and "Gradual Descent". As a result, we successfully completed the project ahead of schedule at Gemini North Telescope. I will discuss how we managed the cultural and human aspects of the project through these concepts. The other management aspects will be presented by Gustavo Arriagada [2], the Project Manager of this project. For technical details, please see presentations from Andrew Serio [3] and Martin Cordova [4].

  11. Gene Transfection in High Serum Levels: Case Studies with New Cholesterol Based Cationic Gemini Lipids

    PubMed Central

    Misra, Santosh K.; Biswas, Joydeep; Kondaiah, Paturu; Bhattacharya, Santanu

    2013-01-01

    Background Six new cationic gemini lipids based on cholesterol possessing different positional combinations of hydroxyethyl (-CH2CH2OH) and oligo-oxyethylene -(CH2CH2O)n- moieties were synthesized. For comparison the corresponding monomeric lipid was also prepared. Each new cationic lipid was found to form stable, clear suspensions in aqueous media. Methodology/Principal Findings To understand the nature of the individual lipid aggregates, we have studied the aggregation properties using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements and X-ray diffraction (XRD). We studied the lipid/DNA complex (lipoplex) formation and the release of the DNA from such lipoplexes using ethidium bromide. These gemini lipids in presence of a helper lipid, 1, 2-dioleoyl phophatidyl ethanol amine (DOPE) showed significant enhancements in the gene transfection compared to several commercially available transfection agents. Cholesterol based gemini having -CH2-CH2-OH groups at the head and one oxyethylene spacer was found to be the most effective lipid, which showed transfection activity even in presence of high serum levels (50%) greater than Effectene, one of the potent commercially available transfecting agents. Most of these geminis protected plasmid DNA remarkably against DNase I in serum, although the degree of stability was found to vary with their structural features. Conclusions/Significance -OH groups present on the cationic headgroups in combination with oxyethylene linkers on cholesterol based geminis, gave an optimized combination of new genera of gemini lipids possessing high transfection efficiency even in presence of very high percentage of serum. This property makes them preferential transfection reagents for possible in vivo studies. PMID:23861884

  12. Reverse micellar extraction of bovine serum albumin - a comparison between the effects of gemini surfactant and its corresponding monomeric surfactant.

    PubMed

    Xiao, Jing; Cai, Juan; Guo, Xia

    2013-01-15

    Gemini surfactant displayed distinct advantages over monomeric surfactant in the liquid-liquid reverse micellar extraction process. First, less amount of gemini surfactant than monomeric surfactant was needed for transferring almost complete bovine serum albumin (BSA) into organic phase from aqueous phase. Second, the loading capacity of gemini surfactant reverse micelle phase was much higher than that of the corresponding monomeric surfactant reverse micelle. Third, efficient backward extraction (75-92%) of BSA could be effected in a wide pH range from 4 to 9 with gemini surfactant reverse micelle while a pH of ca. 4.3 is prerequisite to the recovery of BSA from monomeric surfactant reverse micelle. So far, the reports about the effect of surfactant structure on protein extraction have been limited. This study indicates the important role of the spacer of gemini surfactant in protein extraction process and may provide more knowledge on how to optimise surfactant structure.

  13. Influence of statistical sequential decay on isoscaling and symmetry energy coefficient in a gemini simulation

    SciTech Connect

    Zhou, P.; Tian, W. D.; Ma, Y. G.; Cai, X. Z.; Fang, D. Q.; Wang, H. W.

    2011-09-15

    Extensive calculations on isoscaling behavior with the sequential-decay model gemini are performed for the medium-to-heavy nuclei in the mass range A=60-120 at excitation energies up to 3 MeV/nucleon. The comparison between the products after the first-step decay and the ones after the entire-steps decay demonstrates that there exists a strong sequential decay effect on the final isoscaling parameters and the apparent temperature. Results show that the apparent symmetry energy coefficient {gamma}{sub app} does not reflect the initial symmetry energy coefficient C{sub sym} embedded in the mass calculation in the present gemini model.

  14. An ultra short pulse reconstruction software applied to the GEMINI high power laser system

    NASA Astrophysics Data System (ADS)

    Galletti, Mario; Galimberti, Marco; Hooker, Chris; Chekhlov, Oleg; Tang, Yunxin; Bisesto, Fabrizio Giuseppe; Curcio, Alessandro; Anania, Maria Pia; Giulietti, Danilo

    2016-09-01

    The GRENOUILLE traces of Gemini pulses (15 J, 30 fs, PW, shot per 20 s) were acquired in the Gemini Target Area PetaWatt at the Central Laser Facility (CLF), Rutherford Appleton Laboratory (RAL). A comparison between the characterizations of the laser pulse parameters made using two different types of algorithms: Video Frog and GRenouille/FrOG (GROG), was made. The temporal and spectral parameters came out to be in great agreement for the two kinds of algorithms. In this experimental campaign it has been showed how GROG, the developed algorithm, works as well as VideoFrog algorithm with the PetaWatt pulse class.

  15. Influence of statistical sequential decay on isoscaling and symmetry energy coefficient in a gemini simulation

    NASA Astrophysics Data System (ADS)

    Zhou, P.; Tian, W. D.; Ma, Y. G.; Cai, X. Z.; Fang, D. Q.; Wang, H. W.

    2011-09-01

    Extensive calculations on isoscaling behavior with the sequential-decay model gemini are performed for the medium-to-heavy nuclei in the mass range A=60-120 at excitation energies up to 3 MeV/nucleon. The comparison between the products after the first-step decay and the ones after the entire-steps decay demonstrates that there exists a strong sequential decay effect on the final isoscaling parameters and the apparent temperature. Results show that the apparent symmetry energy coefficient γapp does not reflect the initial symmetry energy coefficient Csym embedded in the mass calculation in the present gemini model.

  16. GEMMA and GEMINI, two dedicated mixed-signal ASICs for Triple-GEM detectors readout

    NASA Astrophysics Data System (ADS)

    Pezzotta, A.; Croci, G.; Costantini, A.; De Matteis, M.; Tagnani, D.; Corradi, G.; Murtas, F.; Gorini, G.; Baschirotto, A.

    2016-03-01

    GEMMA and GEMINI, two integrated-circuit front-ends for the Triple-GEM detector are presented. These two ASICs aim to improve detector readout performance in terms of count rate, adaptability, portability and power consumption. GEMMA target is to embed counting, timing and spectroscopic measurements in a single 8-channel device, managing a detector capacitance up to 15 pF. On the other hand, GEMINI is dedicated to counting measurements, embedding 16 channels with a detector capacitance up to 40 pF. Both prototypes, fabricated in 130 nm and 180 nm CMOS respectively, feature an automatic on-chip calibration circuit, compensating for process/temperature variations.

  17. Modern Gemini-Approach to Technology Development for Human Space Exploration

    NASA Technical Reports Server (NTRS)

    White, Harold

    2010-01-01

    In NASA's plan to put men on the moon, there were three sequential programs: Mercury, Gemini, and Apollo. The Gemini program was used to develop and integrate the technologies that would be necessary for the Apollo program to successfully put men on the moon. We would like to present an analogous modern approach that leverages legacy ISS hardware designs, and integrates developing new technologies into a flexible architecture This new architecture is scalable, sustainable, and can be used to establish human exploration infrastructure beyond low earth orbit and into deep space.

  18. Gemini near-infrared observations of Europa's Hydrated Surface Materials

    NASA Astrophysics Data System (ADS)

    Tsang, C.; Spencer, J. R.; Grundy, W. M.; Dalton, J. B.

    2012-12-01

    Europa is a highly dynamic icy moon of Jupiter. It is thought the moon harbors a subsurface ocean, with the potential to sustain life, with Europa being a key target of ESA's forthcoming Jupiter Icy Moons Orbiter (JUICE) mission. However, much is not known concerning the chemistry of the subsurface ocean. The surface is dominated by water ice, with a hydrated non-ice material component providing the distinctive albedo contrasts seen at visible and near-infrared wavelengths. These non-ice materials are concentrated at disrupted surface regions, providing a diagnostic probe for the chemistry and characteristics of the liquid ocean beneath. Leading but potentially competing theories on the composition of these hydrated non-ice materials suggest either sulfuric acid-water mixtures (Carlson et al., 1999) or hydrated magnesium/sodium salts (McCord et al., 1999). Recent reanalysis of Galileo-NIMS observations suggest a mixture of both - hydrated salts are present at all longitudes but the sulfuric acid hydrates are localized on the trailing side. We present preliminary analysis of new ground-based Gemini disk-resolved spectroscopy of Europa using the Near-Infrared Integrated Field Spectrometer (NIFS), taken in late 2011, at H (1.49 - 1.80 μm) and K bands (1.99 - 2.40 μm) with spectral resolving powers of ~ 5300. At these NIR wavelengths, with spectral resolution much better than Galileo-NIMS, the spectral absorption and continuum characteristics of these ice and non-ice materials can be separated out. In addition, the spatial resolution potentially allows identification of localized materials whose signature would be diluted in disk-integrated spectra. These observations of the trailing hemisphere use Altair adaptive optics to achieve spatial resolutions of 0.1" (~310 km per pixel) or better, potentially leading to better identification of the non-ice materials and their spatial distributions. References Carlson, R.W., R.E. Johnson, and M.S. Anderson 1999. Sulfuric acid

  19. Some results of biomedical studies carried out in the Gemini and Apollo programs

    NASA Technical Reports Server (NTRS)

    Kopanev, V. I.; Yuganov, Y. M.

    1975-01-01

    Biomedical changes in Gemini and Apollo astronauts indicate physiological shifts in the majority of organs and systems of the body during space flight. Weightlessness conditions affected body weight, blood circulation, hematological indices, metabolisms, etc. Prophylactic measures to minimize the various physiological and psychological effects constitute activity and rest cycles, supplementary potassium addition to space food, artificial gravity, etc.

  20. Structural analysis and biological activities of BXL0124, a gemini analog of vitamin D.

    PubMed

    Belorusova, Anna Y; Suh, Nanjoo; Lee, Hong Jin; So, Jae Young; Maehr, Hubert; Rochel, Natacha

    2016-09-17

    Gemini analogs of calcitriol, characterized by the extension of the C21-methyl group of calcitriol with a second chain, act as agonists of the vitamin D receptor (VDR). This second side chain of gemini is accommodated in a new cavity inside the VDR created by the structural rearrangement of the protein core. The resulting conformational change preserves the active state of the receptor and bestows gemini compounds with biological activities that exceed those of calcitriol. Of particular interest are gemini's anti-cancer properties, and in this study we demonstrate anti-proliferative and tumor-reducing abilities of BXL0124 and BXL0097, differing only by the presence or absence, respectively, of the methylene group on the A ring. BXL0124 acts as a more potent VDR agonist than its 19-nor counterpart by activating VDR-mediated transcription at lower concentrations. In a similar manner, BXL0124 is more active than BXL0097 in growth inhibition of breast cancer cells and reduction of tumor volume. Structural comparisons of BXL0097 and BXL0124, as their VDR complexes, explain the elevated activity of the latter.

  1. Interactions between DNA and gemini surfactant: impact on gene therapy: part II.

    PubMed

    Ahmed, Taksim; Kamel, Amany O; Wettig, Shawn D

    2016-02-01

    Nonviral gene delivery, provides distinct treatment modalities for the inherited and acquired diseases, relies upon the encapsulation of a gene of interest, which is then ideally delivered to the target cells. Variations in the chemical structure of gemini surfactants and subsequent physicochemical characteristics of the gemini-based lipoplexes and their impact on efficient gene transfection were assessed in part I, which was published in first March 2016 issue of Nanomedicine (1103). In order to design an efficient vector using gemini surfactants, the interaction of the surfactant with DNA and other components of the delivery system must be characterized, and more critically, well understood. Such studies will help to understand how nonviral transfection complexes, in general, overcome various cellular barriers. The Langmuir-Blodgett monolayer studies, atomic force microscopy, differential scanning calorimetry, isothermal titration calorimetry, small-angle x-ray scattering, are extensively used to evaluate the interaction behavior of gemini surfactants with DNA and other vector components. Part II of this review focuses on the use of these unique techniques to understand their interaction with DNA.

  2. GeMini Plus: A Versatile Gamma-Ray Spectrometer for Planetary Composition Measurements

    NASA Astrophysics Data System (ADS)

    Burks, M. T.; Heffern, L. E.; Lawrence, D. J.; Goldsten, J. O.; Peplowski, P. N.

    2016-10-01

    GeMini Plus is a high-resolution, low-resource, gamma-ray spectrometer for planetary composition measurements. The core of the instrument has a mass of 3 kg and requires 10 watts power, making it well suited for both landed and orbital missions.

  3. Gemini 11 Commander Conrad and Pilot Gordon at post flight press conference

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Gemini 11 Commander Charles Conrad, Jr (left) and Pilot Richard F. Gordon, Jr describe mission activities during their post flight press conference at JSC. Gordon at the microphone talks about the extravehicular activity (EVA) photo projected behind the two crewmembers. During the EVA Gordon attached a tether to the Agena and retrieved a nuclear emulsion experiment package.

  4. Gemini 4 prime crew with Official medical nurse for Astronaut crew members

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Gemini 4 prime crew, Astronauts Edward H. White II, (left), and James A. McDivitt (right) are shown with Lt. Dolores (Dee) O'Hare, US Air Force, Center Medical Office, Flight Medicine Branch, Manned Spaceflight Center (MSC). Lieutenant O'Hare has served during several space flights as Official medical nurse for the astronaut crew members on the missions.

  5. Performance of the Gemini Planet Imager’s adaptive optics system

    DOE PAGES

    Poyneer, Lisa A.; Palmer, David W.; Macintosh, Bruce; ...

    2016-01-07

    The Gemini Planet Imager’s adaptive optics (AO) subsystem was designed specifically to facilitate high-contrast imaging. We give a definitive description of the system’s algorithms and technologies as built. Ultimately, the error budget indicates that for all targets and atmospheric conditions AO bandwidth error is the largest term.

  6. Orienete Province, eastern end of Cuba as seen from Gemini 7 spacecraft

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Oriente Province, eastern end of Cuba is photographed by Astronaut Frank Borman and James A. Lovell during the 14th revolution of the Gemini 7 mission. Guantanamo Bay is in the center of picture on southern coast of Cuba. Santiago de Cuba is located about one inch from the bottom edge of the picture, or about three inches westward down the coast from Guantanamo.

  7. Gemini 12 crew cut cake aboard U.S.S. Wasp

    NASA Technical Reports Server (NTRS)

    1966-01-01

    A happy Gemini 12 prime crew slice a cake made aboard the aircraft carrier, U.S.S. Wasp. Astronauts James A. Lovell Jr. (left), command pilot, and Edwin E. Aldrin Jr., pilot, had just been picked up from the splashdown area by helicopter.

  8. Crewmen of the U.S.S. Wasp watching recovery of Gemini 6 spacecraft

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Crewmen of the aircraft carrier U.S.S. Wasp gather on deck to watch the recovery of the Gemini 6 spacecraft and astronauts. Note the signs hanging from the railings which say 'Seasons Greetings from WASP' and 'Spirit of 76'.

  9. Crewmen of the U.S.S. Wasp watching recovery of Gemini 7 spacecraft

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Crewmen of the aircraft carrier U.S.S. Wasp gather on deck to watch the recovery of the Gemini 7 spacecraft and astronauts. Note the signs hanging from the railings which say 'Seasons Greetings from WASP' and 'Spirit of 76'.

  10. Gemini 9-A astronauts welcomed aboard U.S.S. Wasp

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronauts Thomas Stafford and Eugene Cernan (right) receive a warm welcome as they arrive aboard the prime recovery ship, the aircraft carrier U.S.S. Wasp. John C. Stonesifer, with the Manned Spacecraft Center's Landing and Recovery Division, stands next to microphone at left. The Gemini 9 spacecraft can be seen in the right background of the view.

  11. Close-up view of Hand Held Maneuvering Unit for Gemini 8

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Close-up view of the Hand Held Maneuvering Unit which will be used by Astronaut David R. Scott during the extravehicular activity on the Gemini 8 space flight. High pressure cold gas released through the unit's nozzles produces the required controlled thrust to maneuver in a zero-gravity environment.

  12. Cationic gemini surfactants with cleavable spacer: chemical hydrolysis, biodegradation, and toxicity.

    PubMed

    Tehrani-Bagha, A R; Holmberg, K; van Ginkel, C G; Kean, M

    2015-07-01

    The paper describes synthesis and characterization of a new type of cationic gemini surfactant, which has dodecyl tails and a spacer that contains an ester bond. The nomenclature used to describe the structure is 12Q2OCO1Q12, with Q being a quaternary ammonium group and the numbers indicating the number of methylene or methyl groups. Due to the close proximity to the two quaternary ammonium groups, the ester bond is very stable on the acid side and very labile already at slightly alkaline conditions. The hydrolysis products are two single chain surfactants (i.e. 12Q2OH and 12Q1COOH) which are less surface active than the intact gemini surfactant. 12Q2OCO1Q12 was found to be readily biodegradable, i.e. it gave more than 60% biodegradation after 28 days. This is interesting because similar gemini surfactants but with ester bonds in the tails instead of the spacer, have previously been found not to be readily biodegradable. The gemini surfactant was found to be toxic to aquatic organisms (ErC50 value of 0.27 mg/l), although less toxic than the two hydrolysis products.

  13. Gemini 9-A astronauts talk to reporters at Ellington field at end of mission

    NASA Technical Reports Server (NTRS)

    1966-01-01

    The Gemini 9-A prime crew, Astronauts Thomas Stafford (left), command pilot, and Eugene Cernan (right), pilot, express their feelings about being home to their families, Manned Spacecraft Center (MSC) Officials, newsmen and well-wishers gathered at Ellington Air Force Base to welcome the astronauts home. At right is George M. Low, MSC Deputy Director.

  14. Gemini 11 prime crew during water egress training in Gulf of Mexico

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronauts Charles Conrad Jr. (left) and Richard F. Gordon Jr. (right), prime crew for Gemini 11 space flight, practice water egress procedures in the Gulf of Mexico. Static Article 5 was used in the training exercise. A Manned Spaceflight Center (MSC) swimmer is in the water assisting in the training.

  15. Biodegradability and aquatic toxicity of quaternary ammonium-based gemini surfactants: Effect of the spacer on their ecological properties.

    PubMed

    Garcia, M Teresa; Kaczerewska, Olga; Ribosa, Isabel; Brycki, Bogumił; Materna, Paulina; Drgas, Małgorzata

    2016-07-01

    Aerobic biodegradability and aquatic toxicity of five types of quaternary ammonium-based gemini surfactants have been examined. The effect of the spacer structure and the head group polarity on the ecological properties of a series of dimeric dodecyl ammonium surfactants has been investigated. Standard tests for ready biodegradability assessment (OECD 310) were conducted for C12 alkyl chain gemini surfactants containing oxygen, nitrogen or a benzene ring in the spacer linkage and/or a hydroxyethyl group attached to the nitrogen atom of the head groups. According to the results obtained, the gemini surfactants examined cannot be considered as readily biodegradable compounds. The negligible biotransformation of the gemini surfactants under the standard biodegradation test conditions was found to be due to their toxic effects on the microbial population responsible for aerobic biodegradation. Aquatic toxicity of gemini surfactants was evaluated against Daphnia magna. The acute toxicity values to Daphnia magna, IC50 at 48 h exposure, ranged from 0.6 to 1 mg/L. On the basis of these values, the gemini surfactants tested should be classified as toxic or very toxic to the aquatic environment. However, the dimeric quaternary ammonium-based surfactants examined result to be less toxic than their corresponding monomeric analogs. Nevertheless the aquatic toxicity of these gemini surfactants can be reduced by increasing the molecule hydrophilicity by adding a heteroatom to the spacer or a hydroxyethyl group to the polar head groups.

  16. Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin.

    PubMed

    Vishvakarma, Vijay K; Kumari, Kamlesh; Patel, Rajan; Dixit, V S; Singh, Prashant; Mehrotra, Gopal K; Chandra, Ramesh; Chakrawarty, Anand Kumar

    2015-05-15

    Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation.

  17. Observations Of The LCROSS Impact With NIFS On The Gemini North Telescope

    NASA Astrophysics Data System (ADS)

    Roth, Katherine; Stephens, A. W.; Trujillo, C. A.; McDermid, R. M.; Woodward, C. E.; Walls, B. D.; Coulson, D. M.; Matulonis, A. C.; Ball, J. G.; Wooden, D. H.

    2010-01-01

    The Lunar CRater Observation and Sensing Satellite (LCROSS) Centaur rocket impacted a permanently shadowed crater near the south pole of the Moon at 11:31 UTC 2009 October 09. Gemini, one of several telescopes in a coordinated network observing the impact, conducted observations using NIFS to obtain 3D K-band imaging spectroscopy to detect water ice in the ejected plume of material. The spectral slope of the NIFS data can constrain the grain size and height distribution as the plume evolves, measuring the total mass and the water ice concentration in the plume. These observations provided an engineering challenge for Gemini, including the need to track non-sidereal with constantly changing track rates and guide on small bright moon craters, in order to keep the impact site within the NIFS field-of-view. High quality images taken by GMOS-N, NIRI and the acquisition camera during engineering periods at specific lunar libration and illumination were also used by the LCROSS ground based observing team to supplement slit positioning and offset plans for other ground based observatories. LCROSS mission support and engineering has resulted in improved telescope functionality for non-sidereal targets, including the ability to upload and import target ephemerides directly into the TCS, starting in semester 2010B. In this poster we present the engineering results and observing improvements which will facilitate enhanced user capabilities of the Gemini telescopes arising from the intensive LCROSS support challenge. Gemini Observatory is operated by AURA, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the NSF (United States), the STFC (United Kingdom), the NRC (Canada), CONICYT (Chile), the ARC (Australia), Ministério da Ciência e Tecnologia (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). In part this research was supported by NASA through contracts to SWRI and NSF grant AST-0706980 to the U

  18. Solution properties and emulsification properties of amino acid-based gemini surfactants derived from cysteine.

    PubMed

    Yoshimura, Tomokazu; Sakato, Ayako; Esumi, Kunio

    2013-01-01

    Amino acid-based anionic gemini surfactants (2C(n)diCys, where n represents an alkyl chain with a length of 10, 12, or 14 carbons and "di" and "Cys" indicate adipoyl and cysteine, respectively) were synthesized using the amino acid cysteine. Biodegradability, equilibrium surface tension, and dynamic light scattering were used to characterize the properties of gemini surfactants. Additionally, the effects of alkyl chain length, number of chains, and structure on these properties were evaluated by comparing previously reported gemini surfactants derived from cystine (2C(n)Cys) and monomeric surfactants (C(n)Cys). 2C(n)diCys shows relatively higher biodegradability than does C(n)Cys and previously reported sugar-based gemini surfactants. Both critical micelle concentration (CMC) and surface tension decrease when alkyl chain length is increased from 10 to 12, while a further increase in chain length to 14 results in increased CMC and surface tension. This indicates that long-chain gemini surfactants have a decreased aggregation tendency due to the steric hindrance of the bulky spacer as well as premicelle formation at concentrations below the CMC and are poorly packed at the air/water interface. Formation of micelles (measuring 2 to 5 nm in solution) from 2C(n)diCys shows no dependence on alkyl chain length. Further, shaking the mixtures of aqueous 2C(n)diCys surfactant solutions and squalane results in the formation of oil-in-water type emulsions. The highly stable emulsions are formed using 2C₁₂diCys or 2C₁₄diCys solution and squalane in a 1:1 or 2:1 volume ratio.

  19. Refolding of urea denatured cytochrome c: Role of hydrophobic tail of the cationic gemini surfactants.

    PubMed

    Patel, Rajan; Mir, Muzaffar Ul Hassan; Singh, Upendra Kumar; Beg, Ilyas; Islam, Asimul; Khan, Abbul Bashar

    2016-12-15

    The refolding of urea denatured horse heart cytochrome c (h-cyt-c) under the influence of ester based cationic gemini surfactants [ethane-1, 2-diyl bis(N, N-dimethyl-N-alkylammoniumacetoxy) dichlorides] 16-E2-16, 14-E2-14 and 12-E2-12 (n-E2-n) was performed by using UV-visible, fluorescence and circular dichroism (CD) spectroscopic techniques. We found that n-E2-n geminis promote the formation of molten globule (MG) like state upon addition into the urea denatured h-cyt-c. The comparative study of refolding of denatured h-cyt-c with n-E2-n, cationic gemini surfactant show stabilization of MG-like state influenced by hydrophobic interactions. The formation of MG-like state from the unfolded protein confirms the presence of some regular structures induced by n-E2-n gemini surfactants. Thermodynamic parameters for refolding of h-cyt-c by n-E2-n were also measured and the m-values of all the refolded states of h-cyt-c by n-E2-n show marked difference. The higher m-values correspond to the larger hydrophobic chain length indicates that refolding ability of the n-E2-n depends on the alkyl chain length. The result is related to the stronger hydrophobic forces due to the presence of two head groups and two hydrophobic hydrocarbon tails. This study showed that these cationic gemini surfactants were efficiently utilized in the protein refolding studies.

  20. Tests of Dynamic Scale Model of Gemini Capsule in the Langley 20-Foot Free-Spinning Tunnel

    NASA Technical Reports Server (NTRS)

    1962-01-01

    Tests of Dynamic Scale Model of Gemini Capsule in the Langley 20-Foot Free-Spinning Tunnel. The film shows three spin tunnel tests of a 1/20 scale model of the Gemini capsule. In the first test, the capsule spins freely. In tests 2 and 3, a drogue parachute is attached to the capsule. [Entire movie available on DVD from CASI as Doc ID 20070030989. Contact help@sti.nasa.gov

  1. Modulation of pyridinium cationic lipid-DNA complex properties by pyridinium gemini surfactants and its impact on lipoplex transfection properties.

    PubMed

    Sharma, Vishnu Dutt; Lees, Julia; Hoffman, Nicholas E; Brailoiu, Eugen; Madesh, Muniswamy; Wunder, Stephanie L; Ilies, Marc A

    2014-02-03

    The study presents the effects of blending a cationic gemini surfactant into cationic lipid bilayers and its impact on the plasmid DNA compaction and delivery process. Using nanoDSC, dynamic light scattering, zeta potential, and electrophoretic mobility measurements, together with transfection (2D- and 3D-) and viability assays, we identified the main physicochemical parameters of the lipid bilayers, liposomes, and lipoplexes that are affected by the gemini surfactant addition. We also correlated the cationic bilayer composition with the dynamics of the DNA compaction process and with transfection efficiency, cytotoxicity, and the internalization mechanism of the resultant nucleic acid complexes. We found that the blending of gemini surfactant into the cationic bilayers fluidized the supramolecular assemblies, reduced the amount of positive charge required to fully compact the plasmid DNA and, in certain cases, changed the internalization mechanism of the lipoplexes. The transfection efficiency of select ternary lipoplexes derived from cationic gemini surfactants and lipids was several times superior to the transfection efficiency of corresponding binary lipoplexes, also surpassing standard transfection systems. The overall impact of gemini surfactants into the formation and dynamic of cationic bilayers was found to depend heavily on the presence of colipids, their nature, and amount present in lipoplexes. The study confirmed the possibility of combining the specific properties of pyridinium gemini surfactants and cationic lipids synergistically to obtain efficient synthetic transfection systems with negligible cytotoxicity useful for therapeutic gene delivery.

  2. Membranes of cationic gemini lipids based on cholesterol with hydroxyl headgroups and their interactions with DNA and phospholipid.

    PubMed

    Biswas, Joydeep; Bajaj, Avinash; Bhattacharya, Santanu

    2011-01-27

    Two series of cholesterol-based cationic gemini lipids with and without hydroxyl functions at the headgroups possessing different lengths of polymethylene [-(CH(2))(n)-] (n = 3, 4, 5, 6, 12) spacer have been synthesized. Each gemini lipid formed stable suspension in water. The suspensions of these gemini lipids in water were investigated using transmission electron microscopy, dynamic light scattering, zeta potential measurements and X-ray diffraction to characterize the nature of the individual aggregates formed therein. The aggregation properties of these gemini lipids in water were found to strongly depend upon the length of the spacer and the presence of hydroxyl group at the headgroup region. Lipoplex formation (DNA binding) and the release of the DNA from such lipoplexes were performed to understand the nature of interactions that prevail between these cationic cholesterol aggregates and duplex DNA. The interactions between such gemini lipids and DNA depend both on the presence of OH on the headgroups and the spacer length between the headgroups. Finally, we studied the effect of incorporation of each cationic gemini lipid into dipalmitoyl phosphatidylcholine vesicles using differential scanning calorimetry. The properties of the resulting mixed membranes were found again to depend upon the nature of the headgroup and the spacer chain length.

  3. Efficient improvement of surface activity of tea saponin through Gemini-like modification by straightforward esterification.

    PubMed

    Feng, Jin; Chen, Ying; Liu, Xin; Liu, Songbai

    2015-03-15

    Novel strategy of Gemini-like modification has been applied in development of new nonionic surfactants, tea saponin esters, with enhanced surface activity by simple esterification. Tea saponin was treated with acyl chlorides of different chain length and different ratio of tea saponin and acyl chloride under alkaline condition. The structures of tea saponin esters were analysed and confirmed by FT-IR, NMR and ESI-MS. Surface activity investigation revealed that esterification with the chain length of C12 and C14 and the ratio of 1:4 to 1:6 produced superior surface activity compared with tea saponin. The exceptional surface activity of the new surfactants suggested their great potential application in food industry as green surfactants due to their environmental benign nature as well as simple and inexpensive preparation. The strategy of Gemini-like modification will facilitate development of green surfactants based on natural resources.

  4. Integrating the Galileoscope into Successfully Established as Well as New Outreach Programs at Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Harvey, J.; Michaud, P.; Slater, T.; Slater, S.; Goldstein, J.

    2011-09-01

    The annual Journey through the Universe program is a flagship Gemini public education/outreach event that engages the public, teachers, astronomers, engineers, and thousands of local students and staff from all of the Mauna Kea Observatories. Now going into its seventh year in Hawaii, the 2010 program has integrated the Galileoscope as an integral part of the ten-day program with teacher workshops, classroom telescope kits, and a new teacher resource package developed for the program. Through the generous donation of Galileoscopes from the Ric and Jean Edelman Foundation and the Astronomical Society of the Pacific, each Project/Family Astro site received Galileoscopes. Each family participating in Gemini's Family Astro event and training program will receive a Galileoscope to take home. Workshops will be offered to the Girl and Boy scouts, the Boys and Girls Club of Hawaii, the County of Hawaii's Department of Parks and Recreation's summer programs, and other community organizations.

  5. A new MOS mask cutter facility at Gemini/Cerro Tololo observatories

    NASA Astrophysics Data System (ADS)

    Wyman, Robert T.; Trancho, Gelys; Tighe, Roberto

    2010-07-01

    The installation and commissioning of a new laser cutter facility in La Serena, Chile is a cooperative effort between Gemini Observatory and the Cerro Tololo Inter-American Observatory. This system enables the cutting of aluminum and carbon fiber slit masks for three multi-object spectrographs operating in Chile: GMOS-S, Flamingos-2, and Goodman spectrograph. Selection of the new laser cutter tool was based on slit mask specifications developed for two materials. Prior to the commissioning all slit mask production was performed at Gemini's Northern base facility with a similar laser cutter system. The new facility supports two observatories and enhances the capabilities for both. This paper will discuss the observatory arrangement with respect to mask data tracking and handling. The laser system and facility will be discussed along with mask cutting performance, process development and manufacturing methods.

  6. Large collaboration in observational astronomy: the Gemini Planet Imager exoplanet survey case

    NASA Astrophysics Data System (ADS)

    Marchis, Franck; Kalas, Paul G.; Perrin, Marshall D.; Konopacky, Quinn M.; Savransky, Dmitry; Macintosh, Bruce; Marois, Christian; Graham, James R.

    2016-08-01

    The Gemini Planet Imager (GPI) is a next-generation high-contrast imager built for the Gemini Observatory. The GPI exoplanet survey (GPIES) consortium is made up of 102 researchers from 28 institutions in North and South America and Europe. In November 2014, we launched a search for young Jovian planets and debris disks. In this paper, we discuss how we have coordinated the work done by this large team to improve the technical and scientific productivity of the campaign, and describe lessons we have learned that could be useful for future instrumentation-based astronomical surveys. The success of GPIES lies mostly on its decentralized structure, clear definition of policies that are signed by each member, and the heavy use of modern tools for communicating, exchanging information, and processing data.

  7. The Gemini High-Resolution Optical SpecTrograph (GHOST) bench spectrograph optical design

    NASA Astrophysics Data System (ADS)

    Pazder, John; Burley, Greg; Ireland, Michael J.; Robertson, Gordon; Sheinis, Andrew; Zhelem, Ross

    2016-08-01

    Gemini High-Resolution Optical SpecTrograph (GHOST) is a fiber-fed spectrograph being developed for the Gemini telescope. GHOST is a white pupil échelle spectrograph with high efficiency and a broad continuous wavelength coverage (363-1000nm) with R>50,000 in two-object mode and >75,000 in single-object mode. The design incorporates a novel zero-Petzval sum white pupil relay to eliminate grating aberrations at the cross-dispersers. Cameras are based on non-achromatic designs with tilted detectors to eliminate the need for exotic glasses. This paper outlines the optical design of the bench-mounted spectrograph and the predicted spectrograph resolution and efficiency for the spectrograph.

  8. Arabian Peninsula and northeast Africa as seen from Gemini 11 spacecraft

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Arabian Peninsula (on left) and northeast Africa (on right) as seen from the Gemini 11 spacecraft at an altitude of 340 nautical miles during its 27th revolution of the earth, looking southeast. Saudia Arabia, South Arabia, Yemen and Aden Protectorate are at left. At bottom right is Ethiopia. French Somaliland is in center on right shore. Somali is at upper right. Body of water at bottom is Red Sea. Gulf of Aden is in center; and at top left is Indian Ocean.

  9. Serine-based gemini surfactants with different spacer linkages: from self-assembly to DNA compaction.

    PubMed

    Silva, Sandra G; Oliveira, Isabel S; do Vale, M Luísa C; Marques, Eduardo F

    2014-12-14

    Cationic gemini surfactants have strong potential as compaction agents of nucleic acids for efficient non-viral gene delivery. In this work, we present the aggregation behavior of three novel cationic serine-based gemini surfactants as well as their ability to compact DNA per se and mixed with a helper lipid, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). All the surfactants have a 12-12-12 configuration, i.e. two main 12-carbon alkyl chains linked to the nitrogen atom of the amino acid residue and a 12 methylene spacer, but they differ in the nature of the spacer linkage: for (12Ser)2N12, an amine bond; for (12Ser)2CON12, an amide bond; and for (12Ser)2COO12, an ester bond. Interestingly, while the amine-based gemini aggregates into micelles, the amide and ester ones spontaneously form vesicles, which denotes a strong influence of the type of linkage on the surfactant packing parameter. The size, ζ-potential and stability of the vesicles have been characterized by light microscopy, cryogenic scanning electron microscopy (cryo-SEM) and dynamic light scattering (DLS). The interaction of the gemini aggregates with DNA at different charge ratios and in the absence and presence of DOPE has been studied by DLS, fluorescence spectroscopy and cryo-SEM. All the compounds are found to efficiently compact DNA (complexation > 90%), but relevant differences are obtained in terms of the size, ζ-potential and stability of the lipoplexes formed. Results are rationalized in terms of headgroup differences and the type of aggregates present prior to DNA condensation.

  10. Structural, biocomplexation and gene delivery properties of hydroxyethylated gemini surfactants with varied spacer length.

    PubMed

    Zakharova, Lucia Ya; Gabdrakhmanov, Dinar R; Ibragimova, Alsu R; Vasilieva, Elmira A; Nizameev, Irek R; Kadirov, Marsil K; Ermakova, Elena A; Gogoleva, Natalia E; Faizullin, Dzhigangir A; Pokrovsky, Andrey G; Korobeynikov, Vladislav A; Cheresiz, Sergey V; Zuev, Yuriy F

    2016-04-01

    Gemini surfactants with hexadecyl tails and hydroxyethylated head groups bridged with tetramethylene (G4), hexamethylene (G6) and dodecamethylene (G12) spacers were shown to self-assemble at the lower critical micelle concentration compared to their conventional m-s-m analogs. The lipoplex formation and the plasmid DNA transfer into different kinds of host cells were studied. In the case of eukaryotic cells, high transfection efficacy has been demonstrated for DNA-gemini complexes, which increased as follows: G6G4>G12 has been obtained in the case of transformation of bacterial cells with plasmid DNA-gemini complexes, mediated by electroporation technique. Solely G6 shows transformation efficacy exceeding the control result (uncomplexed DNA), while the inhibitory effect occurs for G4 and G12. Analysis of physico-chemical features of single surfactants and lipoplexes shows that compaction and condensation effects change as follows: G6gemini in the case of transformation of bacterial cells. They are (i) an unfavorable influence of cationic surfactants on the electroporation procedure due to depressing the electrophoretic effect; and (ii) antibacterial activity of cationic surfactants that may cause the disruption of integrity of cell membranes.

  11. Physicochemical properties of oleic acid-based partially fluorinated gemini surfactants.

    PubMed

    Sakai, Kenichi; Umemoto, Naoki; Aburai, Kenichi; Takamatsu, Yuichiro; Endo, Takeshi; Kitiyanan, Boonyarach; Matsumoto, Mutsuyoshi; Sakai, Hideki; Abe, Masahiko

    2014-01-01

    We have developed oleic acid-based partially fluorinated gemini surfactants with carboxylic acid headgroups. The fluorocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via a -CH(2)CH(2)OCO- unit, and the carboxylic acid headgroups are introduced to the cis double bond of oleic acid via -OCOCH(2)CH(2)- units. The aqueous solution properties of these surfactants were studied at pH 9 in the presence of 10 mmol dm–3 NaCl by means of static surface tension, pyrene fluorescence, and dynamic light scattering measurements. The resulting surface tension data demonstrate that the partially fluorinated gemini surfactants exhibit excellent surface activity in their dilute aqueous solutions. In addition, the surfactants are suggested to form micellar aggregates 2–4 nm in diameter. We also studied the aqueous temperature-concentration phase diagrams of the partially fluorinated gemini surfactants (disodium salts) on the basis of visual observations (through a crossed polarizer), polarized optical microscopy, and small angle X-ray scattering measurements. Several phase states including micellar solution phase, hexagonal phase, bicontinuous cubic phase, and lamellar phase were observed along with the coexistence of these phases in certain regions. Assemblies with lesser positive curvature tend to be formed with increasing surfactant concentration, increasing temperature, and increasing fluorocarbon chain length. A comparison of the phase diagrams of the partially fluorinated and hydrogenated surfactant systems suggests that close molecular packing is inhibited within the assemblies of the partially fluorinated surfactants because of the limited miscibility between the fluorocarbon and hydrocarbon units. To the best of our knowledge, this is the first systematic report focusing on the temperature-concentration phase diagrams of (partially) fluorinated gemini surfactants over a wide range of compositions and temperatures.

  12. Questions and Answers for Ken Thomas' "Intra-Extra Vehicular Activity Russian and Gemini Spacesuits" Presentation

    NASA Technical Reports Server (NTRS)

    Thomas, Kenneth S.

    2016-01-01

    Kenneth Thomas will discuss the Intra-Extra Vehicular Activity Russian & Gemini spacesuits. While the United States and Russia adapted to existing launch- and reentry-type suits to allow the first human ventures into the vacuum of space, there were differences in execution and capabilities. Mr. Thomas will discuss the advantages and disadvantages of this approach compared to exclusively intravehicular or extra-vehicular suit systems.

  13. The Gemini NICI Planet-Finding Campaign: The Companion Detection Pipeline

    NASA Astrophysics Data System (ADS)

    Wahhaj, Zahed; Liu, Michael C.; Biller, Beth A.; Nielsen, Eric L.; Close, Laird M.; Hayward, Thomas L.; Hartung, Markus; Chun, Mark; Ftaclas, Christ; Toomey, Douglas W.

    2013-12-01

    We present high-contrast image processing techniques used by the Gemini NICI Planet-Finding Campaign to detect faint companions to bright stars. The Near-Infrared Coronographic Imager (NICI) is an adaptive optics instrument installed on the 8 m Gemini South telescope, capable of angular and spectral difference imaging and specifically designed to image exoplanets. The Campaign data pipeline achieves median contrasts of 12.6 mag at 0.''5 and 14.4 mag at 1'' separation, for a sample of 45 stars (V = 4.3-13.9 mag) from the early phase of the campaign. We also present a novel approach to calculating contrast curves for companion detection based on 95% completeness in the recovery of artificial companions injected into the raw data, while accounting for the false-positive rate. We use this technique to select the image processing algorithms that are more successful at recovering faint simulated point sources. We compare our pipeline to the performance of the Locally Optimized Combination of Images (LOCI) algorithm for NICI data and do not find significant improvement with LOCI. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  14. The opto-mechanical design for GMOX: a next-generation instrument concept for Gemini

    NASA Astrophysics Data System (ADS)

    Smee, Stephen A.; Barkhouser, Robert; Robberto, Massimo; Ninkov, Zoran; Gennaro, Mario; Heckman, Timothy M.

    2016-08-01

    We present the opto-mechanical design of GMOX, the Gemini Multi-Object eXtra-wide-band spectrograph, a potential next-generation (Gen-4 #3) facility-class instrument for Gemini. GMOX is a wide-band, multi-object, spectrograph with spectral coverage spanning 350 nm to 2.4 um with a nominal resolving power of R 5000. Through the use of Digital Micromirror Device (DMD) technology, GMOX will be able to acquire spectra from hundreds of sources simultaneously, offering unparalleled flexibility in target selection. Utilizing this technology, GMOX can rapidly adapt individual slits to either seeing-limited or diffraction-limited conditions. The optical design splits the bandpass into three arms, blue, red, and near infrared, with the near-infrared arm being split into three channels covering the Y+J band, H band, and K band. A slit viewing camera in each arm provides imaging capability for target acquisition and fast-feedback for adaptive optics control with either ALTAIR (Gemini North) or GeMS (Gemini South). Mounted at the Cassegrain focus, GMOX is a large (1.3 m x 2.8 m x 2.0 m) complex instrument, with six dichroics, three DMDs (one per arm), five science cameras, and three acquisition cameras. Roughly half of these optics, including one DMD, operate at cryogenic temperature. To maximize stiffness and simplify assembly and alignment, the opto-mechanics are divided into three main sub-assemblies, including a near-infrared cryostat, each having sub-benches to facilitate ease of alignment and testing of the optics. In this paper we present the conceptual opto-mechanical design of GMOX, with an emphasis on the mounting strategy for the optics and the thermal design details related to the near-infrared cryostat.

  15. Interaction of two imidazolium gemini surfactants with two model proteins BSA and HEWL.

    PubMed

    Gospodarczyk, W; Kozak, M

    Gemini surfactants and their interactions with proteins have gained considerable scientific interest, especially when amyloidogenic proteins are taken into account. In this work, the influence of two selected dicationic (gemini) surfactants (3,3'-[1,8-(2,7-dioxaoctane)]bis(1-dodecylimidazolium) chloride and 3,3'-[1,12-(2,11-dioxadodecane)]bis(1-dodecylimidazolium) chloride) on two model proteins, bovine serum albumin (BSA) and hen egg white lysozyme (HEWL), have been investigated. A pronounced and sophisticated influence on BSA structure has been revealed, including a considerable change of protein radius of gyration as well as substantial alteration of its secondary structure. Radius of gyration has been found to rise significantly with addition of surfactants and to fall down for high surfactants concentration. Similarly, a remarkable fall of secondary structure (α-helix content) has been observed, followed by its partial retrieval for high surfactants concentration. A strong aggregation of BSA has been observed for a confined range of surfactants concentrations as well. In case of HEWL-gemini system, on the other hand, the protein-surfactant interaction was found to be weak. Molecular mechanisms explaining such behaviour of protein-surfactant systems have been proposed. The differences of properties of both studied surfactants have also been discussed.

  16. Design, Synthesis and Biological Activities of Novel Gemini 20S-Hydroxyvitamin D3 Analogs.

    PubMed

    Lin, Zongtao; Marepally, Srinivasa R; Kim, Tae-Kang; Janjetovic, Zorica; Oak, Allen Sw; Postlethwaite, Arnold E; Myers, Linda K; Tuckey, Robert C; Slominski, Andrzej T; Miller, Duane D; Li, Wei

    2016-03-01

    Vitamin D3 (D3) can be metabolized by cytochrome P450scc (CYP11A1) into 20S-hydroxyvitamin D3 (20D3) as a major metabolite. This bioactive metabolite has shown strong antiproliferative, antifibrotic, pro-differentiation and anti-inflammatory effects while being non-toxic (non-calcemic) at high concentrations. Since D3 analogs with two symmetric side chains (Gemini analogs) result in potent activation of the vitamin D receptor (VDR), we hypothesized that the chain length and composition of these types of analogs also containing a 20-hydroxyl group would affect their biological activities. In this study, we designed and synthesized a series of Gemini 20D3 analogs. Biological tests showed that some of these analogs are partial VDR activators and can significantly stimulate the expression of mRNA for VDR and VDR-regulated genes including CYP24A1 and transient receptor potential cation channel V6 (TRPV6). These analogs inhibited the proliferation of melanoma cells with potency comparable to that of 1α,25-dihydroxyvitamin D3. Moreover, these analogs reduced the level of interferon γ and up-regulated the expression of leukocyte associated immunoglobulin-like receptor 1 in splenocytes, indicating that they have potent anti-inflammatory activities. There are no clear correlations between the Gemini chain length and their VDR activation or biological activities, consistent with the high flexibility of the ligand-binding pocket of the VDR.

  17. Design, Synthesis and Biological Activities of Novel Gemini 20S-Hydroxyvitamin D3 Analogs

    PubMed Central

    LIN, ZONGTAO; MAREPALLY, SRINIVASA R.; KIM, TAE-KANG; JANJETOVIC, ZORICA; OAK, ALLEN SW.; POSTLETHWAITE, ARNOLD E.; MYERS, LINDA K.; TUCKEY, ROBERT C.; SLOMINSKI, ANDRZEJ T.; MILLER, DUANE D.; LI, WEI

    2017-01-01

    Vitamin D3 (D3) can be metabolized by cytochrome P450scc (CYP11A1) into 20S-hydroxyvitamin D3 (20D3) as a major metabolite. This bioactive metabolite has shown strong antiproliferative, antifibrotic, pro-differentiation and anti-inflammatory effects while being non-toxic (non-calcemic) at high concentrations. Since D3 analogs with two symmetric side chains (Gemini analogs) result in potent activation of the vitamin D receptor (VDR), we hypothesized that the chain length and composition of these types of analogs also containing a 20-hydroxyl group would affect their biological activities. In this study, we designed and synthesized a series of Gemini 20D3 analogs. Biological tests showed that some of these analogs are partial VDR activators and can significantly stimulate the expression of mRNA for VDR and VDR-regulated genes including CYP24A1 and transient receptor potential cation channel V6 (TRPV6). These analogs inhibited the proliferation of melanoma cells with potency comparable to that of 1α,25-dihydroxyvitamin D3. Moreover, these analogs reduced the level of interferon γ and up-regulated the expression of leukocyte associated immunoglobulin-like receptor 1 in splenocytes, indicating that they have potent anti-inflammatory activities. There are no clear correlations between the Gemini chain length and their VDR activation or biological activities, consistent with the high flexibility of the ligand-binding pocket of the VDR. PMID:26976974

  18. Implementing an Education and Outreach Program for the Gemini Observatory in Chile.

    NASA Astrophysics Data System (ADS)

    Garcia, M. A.

    2006-08-01

    Beginning in 2001, the Gemini Observatory began the development of an innovative and aggressive education and outreach program at its Southern Hemisphere site in northern Chile. A principal focus of this effort is centered on local education and outreach to communities surrounding the observatory and its base facility in La Serena Chile. Programs are now established with local schools using two portable StarLab planetaria, an internet-based teacher exchange called StarTeachers and multiple partnerships with local educational institutions. Other elements include a CD-ROM-based virtual tour that allows students, teachers and the public to experience the observatory's sites in Chile and Hawaii. This virtual environment allows interaction using a variety of immersive scenarios such as a simulated observation using real data from Gemini. Pilot projects like "Live from Gemini" are currently being developed which use internet videoconferencing technologies to bring the observatory's facilities into classrooms at universities and remote institutions. Lessons learned from the implementation of these and other programs will be introduced and the challenges of developing educational programming in a developing country will be shared.

  19. Unexpected role of linker position on ammonium gemini surfactant lyotropic gyroid phase stability.

    PubMed

    Sorenson, Gregory P; Mahanthappa, Mahesh K

    2016-02-28

    Arising from the water-driven self-assembly of amphiphiles over generally narrow temperature and composition phase windows, aqueous lyotropic liquid crystal (LLC) network phases are useful in applications as therapeutic delivery vehicles and templates for mesoporous material syntheses. While a clear set of amphiphile design rules that enables access to these intricate three-dimensional structures has yet to emerge, recent work indicates that bis(ammonium), bis(phosphonium), and dicarboxylate gemini ("twin tail") surfactants enable enhanced access to LLC network phases such as the double gyroid (G). In order to better understand the scope of this amphiphile design strategy, we investigated the synthesis and aqueous LLC self-assembly behaviors of a homologous series of quaternary gemini bis(ammonium) dichloride surfactants, in which we varied the position of the hydrophobic linker that connects the constituent single tail surfactants. These experiments demonstrate that the position of the linker directly impacts the maximum counterion-headgroup hydration capacity and the extent of counterion-headgroup association, all of which contribute to the aqueous lyotropic double gyroid network phase stability. Thus, judicious selection of the linker position in ionic gemini surfactants provides a new molecular design tool for manipulating LLC network phase stability.

  20. The survival of terrestrial microorganisms in space at orbital altitudes during Gemini satellite experiments.

    PubMed

    Hotchin, J; Lorenz, P; Hemenway, C L

    1968-01-01

    In a previous series of rocket- and satellite-borne experiments, microorganisms were exposed to space between altitudes of 60 to 460 km for periods between 3 minutes and 4 months. The results showed that some of the unprotected microorganisms survived the direct exposure for up to 17 hours. Complete survival was found when the microorganisms were shielded from nonpenetrating radiation. These results made it desirable to systematically study the lethal influence of the space environment on a wider spectrum of unprotected microorganisms over various exposure periods. This communication presents the results of exposure experiments on board the Gemini XII satellite. The microorganisms were dried on plastic coated aluminum plates using techniques which will be described elsewhere. During the flight of the Gemini XII space capsule, the microorganisms were directly exposed to space for approximately 6 1/2 hours. After the successful completion of the Gemini XII mission the payload was returned to the laboratory for elution and titration of the microorganisms using techniques described elsewhere. The results showed that again survival of some microorganisms had occurred. An attempt is made to integrate these results with data obtained in previously published experiments.

  1. Effect of amide bonds on the self-assembly of gemini surfactants.

    PubMed

    Hoque, Jiaul; Gonuguntla, Spandhana; Yarlagadda, Venkateswarlu; Aswal, Vinod K; Haldar, Jayanta

    2014-06-21

    This study provides an insight into the micellar aggregation properties in aqueous solutions of various gemini surfactants bearing one or more amide groups at the side chains and/or in the spacer by conductivity and small angle neutron scattering (SANS) studies. The amide functionality was found to enhance the surfactant aggregation properties as compared to the surfactants having no amide bond. Furthermore, the aggregation properties of the gemini surfactants bearing amide groups were found to strongly depend on the position and number of amide bonds. With the increase in the number of amide bonds, the aggregation number (N) and the size of the micelles increased. Additionally, the size and shape of the micelles were also found to depend both on the hydrocarbon chain length and the spacer chain length. It was also found that the aggregation number and the size of the micelles increased with an increase in concentration and decreased with an increase in temperature. The critical micellar concentration (CMC) values of the gemini surfactants obtained by a conductometric method were found to vary greatly with variation in the hydrocarbon chain.

  2. Syntheses, transfection efficacy and cell toxicity properties of novel cholesterol-based gemini lipids having hydroxyethyl head group.

    PubMed

    Biswas, Joydeep; Mishra, Santosh K; Kondaiah, Paturu; Bhattacharya, Santanu

    2011-06-21

    We have synthesized five new cholesterol based gemini cationic lipids possessing hydroxyethyl (-CH(2)CH(2)OH) function on each head group, which differ in the length of the polymethylene spacer chain. These gemini lipids are important for gene delivery processes as they possess pre-optimized molecular features, e.g., cholesterol backbone, ether linkage and a variable spacer chain between both the headgroups of the gemini lipids. Cationic liposomes were prepared from each of these lipids individually and as a mixture of individual cationic gemini lipid and 1,2-dioleoyl phosphatidylethanolamine (DOPE). Each gemini lipid based formulation induced better transfection activity than that of their monomeric counterpart. One such gemini lipid with a -(CH(2))(12)- spacer, HG-12, showed dramatic increase in the mean fluorescence intensity due to the expression of green-fluorescence protein (GFP) in the presence of 10% FBS compared to the conditions where there was no serum. Other gemini lipids retained their gene transfection efficiency without any marked decrease in the presence of serum. The only exception was seen with the gemini with a -(CH(2))(3)- spacer, HG-3, which on gene transfection in the presence of 10% FBS lost ~70% of its transfection efficiency. Overall the gemini lipid with a -(CH(2))(5)- spacer, HG-5, showed the highest transfection activity at N/P (lipid/DNA) ratio of 0.5 and lipid : DOPE molar ratio of 2. Upon comparison of the relevant parameters, e.g., %-transfected cells, the amount of DNA transfected to each cell and %-cell viability all together against Lipofectamine 2000, one of the best commercial transfecting agents, the optimized lipid formulation based on DOPE/HG-5 was found to be comparable. In terms of its ability to induce gene-transfer in the presence of serum and shelf-life DOPE/HG-5 liposome was found to be superior to its commercial counterpart. Confocal imaging analysis confirmed that in the presence of 10% serum using a Lipid : DOPE of 1

  3. D-glucose derived novel gemini surfactants: synthesis and study of their surface properties, interaction with DNA, and cytotoxicity.

    PubMed

    Kumar, Vikash; Chatterjee, Amrita; Kumar, Nupur; Ganguly, Anasuya; Chakraborty, Indranil; Banerjee, Mainak

    2014-10-09

    Four new D-glucose derived m-s-m type gemini surfactants with variable spacer and tail length have been synthesized by a simple and efficient synthetic methodology utilizing the free C-3 hydroxy group of diisopropylidene glucose. The synthetic route to these gemini surfactants with a quaternary ammonium group as polar head group involves a sequence of simple reactions including alkylation, imine formation, quaternization of amine etc. The surface properties of the new geminis were evaluated by surface tension and conductivity measurements. These gemini surfactants showed low cytotoxicity by MTT assay on HeLa cell line. The DNA binding capabilities of these surfactants were determined by agarose gel electrophoresis, fluorescence titration, and DLS experiments. The preliminary studies by agarose gel electrophoresis indicated chain length dependent DNA binding abilities, further supported by ethidium bromide exclusion experiments. Two of the D-glucose derived gemini surfactants showed effective binding with pET-28a plasmid DNA (pDNA) at relatively low N/P ratio (i.e., cationic nitrogen/DNA phosphate molar ratio).

  4. The interactions between cationic cellulose and Gemini surfactant in aqueous solution.

    PubMed

    Zhao, Shaojing; Cheng, Fa; Chen, Yu; Wei, Yuping

    2016-05-05

    Due to the extensive application of cationic cellulose in cosmetic, drug delivery and gene therapy, combining the improvement effect of surfactant-cellulose complexes, to investigate the properties of cellulose in aqueous solution is an important topic from both scientific and technical views. In this study, the phase behavior, solution properties and microstructure of Gemini surfactant sodium 5-nonyl-2-(4-(4-nonyl-2-sulfonatophenoxy)butoxy)phenyl sulfite (9-4-9)/cationic cellulose (JR400, the ammonium groups are directly bonded to the hydroxyethyl substituent with a degree substitution of 0.37) mixture was investigated using turbidity, fluorescence spectrophotometer and shear rheology techniques. As a control, the interaction of corresponding monovalent surfactant, sodium 2-ethoxy-5-nonylbenzenesulfonate (9-2) with JR400 in aqueous solution was also studied. Experimental results showed that 9-4-9/JR400 mixture has lower critical aggregation concentration (CAC) and critical micelle concentration (CMC) (about one order of magnitude) than 9-2/JR400 mixture. A low concentration of Gemini surfactant 9-4-9 appeared to induce an obvious micropolarity and viscosity value variation of the mixture, while these effects required a high concentration of corresponding monovalent one. Furthermore, dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements illuminated the formation and collapse procedure of network structure of the 9-4-9/JR400 mixture, which resulted in the increase and decrease of viscosity. These results suggest that the molecular structure of the surfactant has a great effect on its interaction with cationic cellulose. Moreover, the Gemini surfactant/cationic cellulose mixture may be used as a potencial stimuli-responsive drug delivery vector which not only load hydrophilic drugs, but also deliver hydrophobic substances.

  5. The optical design of GMOX: a next-generation instrument concept for Gemini

    NASA Astrophysics Data System (ADS)

    Barkhouser, Robert; Robberto, Massimo; Smee, Stephen A.; Ninkov, Zoran; Gennaro, Mario; Heckman, Timothy

    2016-08-01

    We present the optical design of GMOX, the Gemini Multi-Object eXtra-wide-band spectrograph. GMOX was selected as part of the Gemini Instrument Feasibility Study to develop capabilities and requirements for the next facility instrument (Gen4#3) for the observatory. We envision GMOX covering the entire optical/near-IR wavelength range accessible from the ground, from 3500 Å in the U band up to 2.4 μm in the K band, with nominal resolving power R≃5,000. To maximize efficiency, the bandpass is split into three spectrograph arms - blue, red, and near-infrared - with the near-infrared arm further split into three channels covering the Y+J, H, and K bands. At the heart of each arm is a Digital Micromirror Device (DMD) serving as a programmable slit array. This technology will enable GMOX to simultaneously acquire hundreds of spectra of faint sources in crowded fields with unparalleled spatial resolution, optimally adapting to both seeing-limited and diffraction limited conditions provided by ALTAIR and GeMS at Gemini North and South, respectively. Fed by GeMS at f/33, GMOX can synthesize slits as small as 40 mas (corresponding to a single HST/WFC3 CCD pixel) over its entire 85"x45" field of view. With either ALTAIR or the native telescope focal ratio of f/16, both the slit and field sizes double. In this paper we discuss the conceptual optical design of GMOX including, for each arm: the pre-slit optics, DMD slit array, off-axis Schmidt collimator, VPH grating, and refractive spectrograph and slit-viewing cameras.

  6. Cationic gemini surfactant-assisted synthesis of hollow Au nanostructures by stepwise reductions.

    PubMed

    Wang, Wentao; Han, Yuchun; Tian, Maozhang; Fan, Yaxun; Tang, Yongqiang; Gao, Mingyuan; Wang, Yilin

    2013-06-26

    A novel synthetic approach was developed for creating versatile hollow Au nanostructures by stepwise reductions of Au(III) upon the use of cationic gemini surfactant hexamethylene-1,6-bis(dodecyl dimethylammonium bromide) (C12C6C12Br2) as a template agent. It was observed that the Au(I) ions obtained from the reduction of Au(III) by ascorbic acid can assist the gemini surfactant to form vesicles, capsule-like, and tube-like aggregates that subsequently act as soft templates for hollow Au nanostructures upon further reduction of Au(I) to Au(0) by NaBH4. It was demonstrated that the combination of C12C6C12Br2 and Au(I) plays a key role in regulating the structure of the hollow precursors not only because C12C6C12Br2 has a stronger aggregation ability in comparison with its single chain counterpart but also because the electrostatic repulsion between head groups of C12C6C12Br2 is greatly weakened after Au(III) is converted to Au(I), which is in favor of the construction of vesicles, capsule-like, and tube-like aggregates. Compared with solid Au nanospheres, the resultant hollow nanostructures exhibit enhanced electrocatalytic activities in methanol oxidation, following the order of elongated nanocapsule > nanocapsule > nanosphere. Benefiting from balanced interactions between the gemini surfactant and Au(I), this soft-template method may present a facile and versatile approach for the controlled synthesis of Au nanostructures potentially useful for fuel cells and other Au nanodevices.

  7. Vesicles from pH-regulated reversible gemini amino-acid surfactants as nanocapsules for delivery.

    PubMed

    Lv, Jing; Qiao, Weihong; Li, Zongshi

    2016-10-01

    Reversible transition from micelles to vesicles by regulating pH were realized by gemini amino-acid surfactants N,N'-dialkyl-N,N'-diacetate ethylenediamine. Measurement results of ζ-potential at different pH and DLS at varying solvents revealed that the protonation between H(+) and double NCH2COO(-) groups (generating NH(+)CH2COO(-)), expressed as pKa1 and pKa2, is the key driving force to control the aggregation behaviors of gemini surfactant molecule. Effect of pH on the bilayer structure was studied in detail by using steady-state fluorescence spectroscopy of hydrophobic pyrene and Coumarin 153 (C153) respectively and fluorescence resonance energy transfer (FRET) from C153 to Rhodamine 6G (R6G). Various pH-regulated and pH-reversible self-assemblies were obtained in one surfactant system. Vitamin D3 was encapsulated in vesicle bilayers to form nano-VD3-capsules as VD3 supplement agent for health care products. By using the electrostatic attraction between Ca(2+) and double -COO(-) groups, nano-VD3-capsules with Ca(2+) coated outermost layers were prepared as a formulation for VD3 and calcium co-supplement agent. DLS and TEM were performed to check stability and morphology of the nano-capsules. It is concluded that the pH-regulated gemini amino-acid surfactants can be used to construct colloidal systems for delivering hydrophobic drugs or nutritions without lipids at human physiological pH level.

  8. Ultra-deep GEMINI Near-infrared Observations of the Bulge Globular Cluster NGC 6624.

    NASA Astrophysics Data System (ADS)

    Saracino, S.; Dalessandro, E.; Ferraro, F. R.; Geisler, D.; Mauro, F.; Lanzoni, B.; Origlia, L.; Miocchi, P.; Cohen, R. E.; Villanova, S.; Moni Bidin, C.

    2016-11-01

    We used ultra-deep J and K s images secured with the near-infrared (NIR) GSAOI camera assisted by the multi-conjugate adaptive optics system GeMS at the GEMINI South Telescope in Chile, to obtain a (K s , J - K s ) color-magnitude diagram (CMD) for the bulge globular cluster NGC 6624. We obtained the deepest and most accurate NIR CMD from the ground for this cluster, by reaching K s ˜ 21.5, approximately 8 mag below the horizontal branch level. The entire extension of the Main Sequence (MS) is nicely sampled and at K s ˜ 20 we detected the so-called MS “knee” in a purely NIR CMD. By taking advantage of the exquisite quality of the data, we estimated the absolute age of NGC 6624 (t age = 12.0 ± 0.5 Gyr), which turns out to be in good agreement with previous studies in the literature. We also analyzed the luminosity and mass functions of MS stars down to M ˜ 0.45 M⊙, finding evidence of a significant increase of low-mass stars at increasing distances from the cluster center. This is a clear signature of mass segregation, confirming that NGC 6624 is in an advanced stage of dynamical evolution. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). Based on observations gathered with ESO-VISTA telescope (program ID 179.B-2002).

  9. The use of a high-order MEMS deformable mirror in the Gemini Planet Imager

    SciTech Connect

    Poyneer, L A; Bauman, B; Cornelissen, S; Jones, S; Macintosh, B; Palmer, D; Isaacs, J

    2010-12-17

    We briefly review the development history of the Gemini Planet Imager's 4K Boston Micromachines MEMS deformable mirror. We discuss essential calibration steps and algorithms to control the MEMS with nanometer precision, including voltage-phase calibration and influence function characterization. We discuss the integration of the MEMS into GPI's Adaptive Optics system at Lawrence Livermore and present experimental results of 1.5 kHz closed-loop control. We detail mitigation strategies in the coronagraph to reduce the impact of abnormal actuators on final image contrast.

  10. α-Gel formation by amino acid-based gemini surfactants.

    PubMed

    Sakai, Kenichi; Ohno, Kiyomi; Nomura, Kazuyuki; Endo, Takeshi; Sakamoto, Kazutami; Sakai, Hideki; Abe, Masahiko

    2014-07-08

    Ternary mixtures being composed of surfactant, long-chain alcohol, and water sometimes form a highly viscous lamellar gel with a hexagonal packing arrangement of their crystalline hydrocarbon chains. This molecular assembly is called "α-crystalline phase" or "α-gel". In this study, we have characterized α-gels formed by the ternary mixtures of amino acid-based gemini surfactants, 1-hexadecanol (C16OH), and water. The surfactants used in this study were synthesized by reacting dodecanoylglutamic acid anhydride with alkyl diamines and abbreviated as 12-GsG-12 (s: the spacer chain length of 2, 5, and 8 methylene units). An amino acid-based monomeric surfactant, dodecanoylglutamic acid (12-Glu), was also used for comparison. At a fixed water concentration the melting point of the α-gel increased with increasing C16OH concentration, and then attained a saturation level at the critical mole ratio of 12-GsG-12/C16OH = 1/2 under the normalization by the number of hydrocarbon chains of the surfactants. This indicates that, to obtain the saturated α-gel, a lesser amount of C16OH is required for the gemini surfactants than for the monomeric one (the critical mole ratio of 12-Glu/C16OH = 1/3). Small- and wide-angle X-ray scattering measurements demonstrated an increase in the long-range d-spacing of the saturated α-gels in the order 12-Glu <12-G8G-12 < 12-G5G-12 < 12-G2G-12. In the three gemini surfactant systems, the decreased spacer chain length resulted in the increased maximum viscosity and elastic modulus of the saturated α-gels at a given water concentration. This is caused by the decreased amount of excess water being present outside the α-gel structure (or the increased amount of water incorporated between the surfactant-alcohol bilayers). To the best of our knowledge, this is the first report focusing on the formation of α-gel in gemini surfactant systems.

  11. Validation of a Monte Carlo simulation of the Philips Allegro/GEMINI PET systems using GATE

    NASA Astrophysics Data System (ADS)

    Lamare, F.; Turzo, A.; Bizais, Y.; Cheze LeRest, C.; Visvikis, D.

    2006-02-01

    A newly developed simulation toolkit, GATE (Geant4 Application for Tomographic Emission), was used to develop a Monte Carlo simulation of a fully three-dimensional (3D) clinical PET scanner. The Philips Allegro/GEMINI PET systems were simulated in order to (a) allow a detailed study of the parameters affecting the system's performance under various imaging conditions, (b) study the optimization and quantitative accuracy of emission acquisition protocols for dynamic and static imaging, and (c) further validate the potential of GATE for the simulation of clinical PET systems. A model of the detection system and its geometry was developed. The accuracy of the developed detection model was tested through the comparison of simulated and measured results obtained with the Allegro/GEMINI systems for a number of NEMA NU2-2001 performance protocols including spatial resolution, sensitivity and scatter fraction. In addition, an approximate model of the system's dead time at the level of detected single events and coincidences was developed in an attempt to simulate the count rate related performance characteristics of the scanner. The developed dead-time model was assessed under different imaging conditions using the count rate loss and noise equivalent count rates performance protocols of standard and modified NEMA NU2-2001 (whole body imaging conditions) and NEMA NU2-1994 (brain imaging conditions) comparing simulated with experimental measurements obtained with the Allegro/GEMINI PET systems. Finally, a reconstructed image quality protocol was used to assess the overall performance of the developed model. An agreement of <3% was obtained in scatter fraction, with a difference between 4% and 10% in the true and random coincidence count rates respectively, throughout a range of activity concentrations and under various imaging conditions, resulting in <8% differences between simulated and measured noise equivalent count rates performance. Finally, the image quality

  12. Comparación fotométrica en imágenes Gemini/GMOS:

    NASA Astrophysics Data System (ADS)

    Escudero, C. G.; Sesto, L. A.; González, N. M.; Faifer, F. R.; Smith Castelli, A.; Forte, J. C.

    2015-08-01

    We compare the performance and reliability of PSFEx and daophot ii in the construction and modeling of the Point Spread Function (PSF) on real images. Both methods were applied over photometric catalogs of globular cluster candidates in the elliptical galaxy NGC1395, generated with SExtractor on Gemini/GMOS images in the filters,,,. We use the PSF photometry obtained from both softwares to compare magnitudes, colour-colour and colour-magnitude diagrams. We also analyzed the new parameter spreadmodel used by SExtractor+PSFEx, which allows to separate point sources from extended objects.

  13. Validation of a Monte Carlo simulation of the Philips Allegro/GEMINI PET systems using GATE.

    PubMed

    Lamare, F; Turzo, A; Bizais, Y; Le Rest, C Cheze; Visvikis, D

    2006-02-21

    A newly developed simulation toolkit, GATE (Geant4 Application for Tomographic Emission), was used to develop a Monte Carlo simulation of a fully three-dimensional (3D) clinical PET scanner. The Philips Allegro/GEMINI PET systems were simulated in order to (a) allow a detailed study of the parameters affecting the system's performance under various imaging conditions, (b) study the optimization and quantitative accuracy of emission acquisition protocols for dynamic and static imaging, and (c) further validate the potential of GATE for the simulation of clinical PET systems. A model of the detection system and its geometry was developed. The accuracy of the developed detection model was tested through the comparison of simulated and measured results obtained with the Allegro/GEMINI systems for a number of NEMA NU2-2001 performance protocols including spatial resolution, sensitivity and scatter fraction. In addition, an approximate model of the system's dead time at the level of detected single events and coincidences was developed in an attempt to simulate the count rate related performance characteristics of the scanner. The developed dead-time model was assessed under different imaging conditions using the count rate loss and noise equivalent count rates performance protocols of standard and modified NEMA NU2-2001 (whole body imaging conditions) and NEMA NU2-1994 (brain imaging conditions) comparing simulated with experimental measurements obtained with the Allegro/GEMINI PET systems. Finally, a reconstructed image quality protocol was used to assess the overall performance of the developed model. An agreement of <3% was obtained in scatter fraction, with a difference between 4% and 10% in the true and random coincidence count rates respectively, throughout a range of activity concentrations and under various imaging conditions, resulting in <8% differences between simulated and measured noise equivalent count rates performance. Finally, the image quality

  14. Gemini/GMOS imaging of globular cluster systems in five early-type galaxies

    NASA Astrophysics Data System (ADS)

    Faifer, Favio R.; Forte, Juan C.; Norris, Mark A.; Bridges, Terry; Forbes, Duncan A.; Zepf, Stephen E.; Beasley, Mike; Gebhardt, Karl; Hanes, David A.; Sharples, Ray M.

    2011-09-01

    In this paper, we present deep high-quality photometry of globular cluster systems (GCSs) belonging to five early-type galaxies, covering a range of mass and environment. Photometric data were obtained with the Gemini North and Gemini South telescopes in the filter passbands g', r' and i'. The combination of these filters with good seeing conditions allows an excellent separation between globular cluster (GC) candidates and unresolved field objects. In fact, our previously published spectroscopic data indicate a contamination level of only ˜10 per cent in our sample of GC candidates. Bimodal GC colour distributions are found in all five galaxies. Most of the GCSs appear bimodal even in the (g'-r') versus (r'-i') plane. A population of resolved/marginally resolved GC and ultracompact dwarf candidates was found in all the galaxies. A search for the so-called 'blue tilt' in the colour-magnitude diagrams reveals that NGC 4649 clearly shows this phenomenon, although no conclusive evidence was found for the other galaxies in the sample. This 'blue tilt' translates into a mass-metallicity relation given by Z∝M0.28 ±0.03. This dependence was found using a new empirical (g'-i') versus [Z/H] relation, which relies on an homogeneous sample of GC colours and metallicities. In this paper, we also explore the radial trends in both colour and surface density for the blue (metal-poor) and red (metal-rich) GC subpopulations. As usual, the red GCs show a steeper radial distribution than the blue GCs. Evidence of galactocentric colour gradients is found in some of the GCSs, which is more significant for the two S0 galaxies in the sample. Red GC subpopulations show similar colours and gradients to the galaxy halo stars in their inner region. A GC mean colour-galaxy luminosity relation, consistent with [Z/H]∝L0.26 ±0.08B, is present for the red GCs. Estimates of the total GC populations and specific frequency SN values are presented for NGC 3115, 3923 and 4649. Based on

  15. GEMINI/GeMS Observations Unveil the Structure of the Heavily Obscured Globular Cluster Liller 1.

    NASA Astrophysics Data System (ADS)

    Saracino, S.; Dalessandro, E.; Ferraro, F. R.; Lanzoni, B.; Geisler, D.; Mauro, F.; Villanova, S.; Moni Bidin, C.; Miocchi, P.; Massari, D.

    2015-06-01

    By exploiting the exceptional high-resolution capabilities of the near-IR camera GSAOI combined with the Gemini Multi-Conjugate Adaptive System at the GEMINI South Telescope, we investigated the structural and physical properties of the heavily obscured globular cluster Liller 1 in the Galactic bulge. We have obtained the deepest and most accurate color-magnitude diagram published so far for this cluster, reaching {{K}s}˜ 19 (below the main-sequence turnoff level). We used these data to redetermine the center of gravity of the system, finding that it is located about 2.″2 southeast from the literature value. We also built new star density and surface brightness profiles for the cluster and rederived its main structural and physical parameters (scale radii, concentration parameter, central mass density, total mass). We find that Liller 1 is significantly less concentrated (concentration parameter c=1.74) and less extended (tidal radius {{r}t}=298\\prime\\prime and core radius {{r}c}=5\\buildrel{\\prime\\prime}\\over{.} 39) than previously thought. By using these newly determined structural parameters, we estimated the mass of Liller 1 to be {{M}tot}=2.3+0.3-0.1× {{10}6} {{M}⊙ } ({{M}tot}=1.5+0.2-0.1× {{10}6} {{M}⊙ } for a Kroupa initial mass function), which is comparable to that of the most massive clusters in the Galaxy (ω Centari and Terzan 5). Also, Liller 1 has the second-highest collision rate (after Terzan 5) among all star clusters in the Galaxy, thus confirming that it is an ideal environment for the formation of collisional objects (such as millisecond pulsars). Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da

  16. Enhancement of soil retention for phenanthrene in binary cationic gemini and nonionic surfactant mixtures: characterizing two-step adsorption and partition processes through experimental and modeling approaches.

    PubMed

    Zhao, Shan; Huang, Gordon; An, Chunjiang; Wei, Jia; Yao, Yao

    2015-04-09

    The enhancement of soil retention for phenanthrene (PHE) through the addition of a binary mixture of cationic gemini (12-2-12) and nonionic surfactants (C12E10) was investigated. The maximum apparent sorption coefficient Kd(*) reached 4247.8 mL/g through the addition of mixed 12-2-12 gemini and C12E10 surfactants, which was markedly higher than the summed individual results in the presence of individual 12-2-12 gemini (1148.6 mL/g) or C12E10 (210.0 mL/g) surfactant. However, the sorption of 12-2-12 gemini was inhibited by the increasing C12E10 dose; and a higher initial 12-2-12 gemini dose showed a higher "desorption" rate. The present study also addressed the sorption behavior of the single 12-2-12 gemini surfactant at the soil/aqueous interface. The sorption isotherm was divided into two steps to elucidate the sorption process; and the sorption schematics were proposed to elaborate the growth of surfactant aggregates corresponding to the various steps of the sorption isotherm. Finally, a two-step adsorption and partition model (TAPM) was developed to simulate the sorption process. Analysis of the equilibrium data indicated that the sorption isotherms of 12-2-12 gemini fitted the TAPM model better. Thermodynamic calculations confirmed that the 12-2-12 gemini sorption at the soil/aqueous interface was spontaneous and exothermic from 288 to 308K.

  17. Synergistic antimicrobial activity based on the combined use of a gemini-quaternary ammonium compound and ultraviolet-A light.

    PubMed

    Shirai, Akihiro; Aihara, Mutsumi; Takahashi, Akira; Maseda, Hideaki; Omasa, Takeshi

    2014-01-05

    This study examined the utility of synergistic disinfection employing a gemini-quaternary ammonium salt (a gemini-QUAT, namely 3,3'-(2,7-dioxaoctane)bis(1-decylpyridinium bromide)), as an organic biocide in combination with irradiation by an ultraviolet-A (UV-A) light-emitting diode (LED) with a peak wavelength of 365nm. The combined system represents a novel disinfection method utilizing facilitated in situ oxidation depending on overproduction of reactive oxygen species (ROS) triggered by the initial action of the gemini-QUAT on the bacterial membrane. We demonstrate that this combination decreased the viability of pathogenic bacteria in a significant and rapid manner, and depended on doses of the gemini-QUAT and the fluence: the viability of Escherichia coli was reduced by greater than 5.0-logs by the combination procedure, but the decrease in viability was only 2.3-logs for exposure to UV at the same fluence dose in the absence of the gemini-QUAT. Adding catalase as a radical scavenger decreased bacterial inactivation by the combined disinfection procedure. Flow cytometric analysis indicated superoxide and hydrogen peroxide overproduction within cells treated with the combined disinfection procedure. The excessive superoxide, detected only in the combined system, appeared to be generated by the action of the gemini-QUAT at the bacterial membrane, leading to excessive and rapid generation of ROS in the system. Our data strongly suggested that this ROS promoted bacterial membrane peroxidation during initial treatment by the combination method, resulting in increased oxidative modification of DNA. These oxidative reactions may play an important role in the efficacy of this disinfection procedure.

  18. Gemini vitamin D analogues inhibit estrogen receptor-positive and estrogen receptor-negative mammary tumorigenesis without hypercalcemic toxicity.

    PubMed

    Lee, Hong Jin; Paul, Shiby; Atalla, Nadi; Thomas, Paul E; Lin, Xinjie; Yang, Ill; Buckley, Brian; Lu, Gang; Zheng, Xi; Lou, You-Rong; Conney, Allan H; Maehr, Hubert; Adorini, Luciano; Uskokovic, Milan; Suh, Nanjoo

    2008-11-01

    Numerous preclinical, epidemiologic, and clinical studies have suggested the benefits of vitamin D and its analogues for the prevention and treatment of cancer. However, the hypercalcemic effects have limited the use of 1alpha,25(OH)(2)D(3), the hormonally active form of vitamin D. To identify vitamin D analogues with better efficacy and low toxicity, we have tested >60 novel Gemini vitamin D analogues with a unique structure of two side chains for growth inhibition of breast cancer cells. Our initial studies found that some Gemini analogues are 5-15 times more active than 1alpha,25(OH)(2)D(3) in growth inhibition assay. In vivo experiments were designed to study the inhibitory effect of selected Gemini vitamin D analogues against mammary carcinogenesis by using (a) an N-methyl-N-nitrosourea-induced estrogen receptor (ER)-positive mammary tumor model and (b) an MCF10DCIS.com xenograft model of ER-negative mammary tumors. Among vitamin D analogues we tested, Gemini 0072 [1alpha,25-dihydroxy-20S-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] and Gemini 0097 [1alpha,25-dihydroxy-20R-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] administration inhibited by 60% the NMU-induced mammary tumor burden compared with the NMU-treated control group, but these compounds were devoid of hypercalcemia toxicity. In an ER-negative xenograft model, Gemini 0097 significantly suppressed tumor growth without hypercalcemia toxicity. We found that the inhibitory effect of Gemini 0097 was associated with an increased level of cyclin-dependent kinase inhibitor p21 and the insulin-like growth factor binding protein 3 in both ER-positive and ER-negative mammary tumors. Our results suggest that Gemini vitamin D analogues may be potent agents for the prevention and treatment of both ER-positive and ER-negative breast cancer without hypercalcemia toxicity.

  19. Role of spacer length in interaction between novel gemini imidazolium surfactants and Rhizopus oryzae lipase.

    PubMed

    Adak, Sunita; Datta, Sougata; Bhattacharya, Santanu; Banerjee, Rintu

    2015-11-01

    An insight into the effects of new ionic liquid-type gemini imidazolium cationic surfactants on the structure and function of the lipases is of prime importance for their potential application. Changes in the activity, stability and structure of Rhizopus oryzae lipase in the presence of novel gemini surfactants, [C16-3-C16im]Br2 and [C16-12-C16im]Br2 were probed in the present study. Surfactant with shorter spacer length, [C16-3-C16im]Br2 was found to be better in improving the hydrolytic activity and thermal stability of the lipase. For both the surfactants, activation was concentration dependent. CD spectroscopy results showed a decrease in α-helix and an increase in β-sheet content in the presence of these surfactants. A higher structural change observed in presence of [C16-12-C16im]Br2 correlated with lower enzyme activity. Isothermal titration calorimetric studies showed the binding to be spontaneous in nature based on sequential two site binding model. The forces involved in binding were found to differ for the two surfactants proving that the spacer length is an important factor which governs the interaction. These surfactants could be used as promising components both in enzyme modification and media engineering for attaining the desired goals in biocatalytic reactions.

  20. GEMINI SPECTROSCOPY OF ULTRACOMPACT DWARFS IN THE FOSSIL GROUP NGC 1132

    SciTech Connect

    Madrid, Juan P.; Donzelli, Carlos J.

    2013-06-20

    A spectroscopic follow-up of ultracompact dwarf (UCD) candidates in the fossil group NGC 1132 is undertaken with the Gemini Multi Object Spectrograph. These new Gemini spectra prove the presence of six UCDs in the fossil group NGC 1132 at a distance of D {approx} 100 Mpc and a recessional velocity of v{sub r} = 6935 {+-} 11 km s{sup -1}. The brightest and largest member of the UCD population is an M32 analog with a size of 77.1 pc and a magnitude of M{sub V} = -14.8 mag with the characteristics in between those of the brightest UCDs and compact elliptical galaxies. The ensemble of UCDs have an average radial velocity of (v{sub r} ) = 6966 {+-} 208 km s{sup -1} and a velocity dispersion of {sigma}{sub v} = 169 {+-} 18 km s{sup -1} similar to the one of poor galaxy groups. This work shows that UCDs can be used as test particles to determine the dynamical properties of galaxy groups. The presence of UCDs in the fossil group environment is confirmed and thus the fact that UCDs can form across diverse evolutionary conditions.

  1. THE INNER ENVELOPE AND DISK OF L1527 REVEALED: GEMINI L'-BAND-SCATTERED LIGHT IMAGING

    SciTech Connect

    Tobin, John J.; Hartmann, Lee; Loinard, Laurent

    2010-10-10

    We present high-resolution L'-band imaging of the inner scattered light structure of Class 0 protostar L1527 IRS (IRAS 04368+2557) taken with the Gemini North telescope. The central point-source-like feature seen in Spitzer Space Telescope IRAC images is resolved in the Gemini image into a compact bipolar structure with a narrow dark lane in the center. Two scattered light lobes are extended {approx}1.''8 (200 AU) perpendicular to the direction of the outflow and {approx}2.''5 (350 AU) along the outflow axis; the narrow dark lane between the scattered light lobes is {approx}0.''45 (60 AU) thick. The observations are consistent with our initial modeling of a bright inner cavity separated by a dark lane due to extinction along the line of sight of the central protostar by the disk. The bright, compact scattered light might be due to complex inner structure generated by the outflow, as suggested in our first paper, or it may more likely be the upper layers of the disk forming from infalling matter.

  2. Interaction of a biosurfactant, Surfactin with a cationic Gemini surfactant in aqueous solution.

    PubMed

    Jin, Lei; Garamus, Vasil M; Liu, Fang; Xiao, Jingwen; Eckerlebe, Helmut; Willumeit-Römer, Regine; Mu, Bozhong; Zou, Aihua

    2016-11-01

    The interaction between biosurfactant Surfactin and cationic Gemini surfactant ethanediyl-1,3-bis(dodecyldimethylammonium bromide) (abbreviated as 12-3-12) was investigated using turbidity, surface tension, dynamic light scattering (DLS) and small angle neutron scattering (SANS). Analysis of critical micelle concentration (CMC) values in Surfactin/12-3-12 mixture indicates that there is synergism in formation of mixed Surfactin/12-3-12 micelles. Although Surfactin and 12-3-12 are oppositely charged in phosphate buffer solution (PBS, pH7.4), there are no precipitates observed at the concentrations below the CMC of Surfactin/12-3-12 system. However, at the concentration above CMC value, the Surfactin/12-3-12 mixture is severely turbid with high 12-3-12 content. DLS and SANS measurements follow the size and shape changes of mixed Surfactin/12-3-12 aggregates from small spherical micelles via elongated aggregates to large bulk complexes with increasing fraction of Gemini surfactant.

  3. Removal of phenol from synthetic waste water using Gemini micellar-enhanced ultrafiltration (GMEUF).

    PubMed

    Zhang, Wenxiang; Huang, Guohe; Wei, Jia; Li, Huiqin; Zheng, Rubing; Zhou, Ya

    2012-10-15

    Comprehensive studies were conducted on the phenol wastewater ultrafiltration (UF) with the help of various concentrations of cationic Gemini surfactant (N1-dodecyl-N1,N1,N2,N2-tetramethyl-N2-octylethane-1,2-diaminium bromide, CG), conventional cationic surfactant (dodecyl trimethyl ammonium bromide, DTAB), anionic surfactant (sodium dodecyl sulfate, SDS) and nonionic surfactant ((dodecyloxy)polyethoxyethanol, Brij35). A flat sheet module with polyethersulfone (PES) membrane was employed in this investigation. The effects of feed concentration (phenol and surfactant) on the retention of phenol and surfactant, permeate flux and membrane fouling by micelles were evaluated. The distribution coefficient (D), the loading of the micelles (L(m)) and the equilibrium distribution constant (K) were also utilized to estimate the micellar-enhanced ultrafiltration ability for phenol. Scanning electron microscope (SEM), Fourier transform infrared spectrometer with attenuated total reflectance accessory (ATR-FTIR) and mercury porosimeter were applied to analyze membrane surface morphology, membrane material characteristics and membrane fouling for the original and fouled membranes. Based on the above analysis, the performance of the selected Gemini surfactant was proved superior in the following aspects: retention of phenol/surfactant (peak value is 95.8% for phenol retention), permeate flux and membrane fouling with respect to other conventional surfactants possessing equal alkyl chain length. These results demonstrated that CG surfactant with exceptional structure has favorable prospects in the treatment of phenol wastewater by the micellar-enhanced ultrafiltration.

  4. Status of the secondary mirrors (M2) for the Gemini 8-m telescopes

    NASA Astrophysics Data System (ADS)

    Knohl, Ernst-Dieter; Schoeppach, Armin; Pickering, Michael A.

    1998-08-01

    The 1-m diameter lightweight secondary mirrors (M2) for the Gemini 8-m telescopes will be the largest CVD-SiC mirrors ever produced. The design and manufacture of these mirrors is a very challenging task. In this paper we will discuss the mirror design, structural and mechanical analysis, and the CVD manufacturing process used to produce the mirror blanks. The lightweight design consist of a thin faceplate (4-mm) and triangular backstructure cells with ribs of varying heights. The main drivers in the design were weight (40 kg) and manufacturing limitations imposed on the backstructure cells and mirror mounts. Finite element modeling predicts that the mirror design will meet all of the Gemini M2 requirements for weight, mechanical integrity, resonances, and optical performance. Special design considerations were necessary to avoid stress concentration in the mounting areas and to meet the requirement that the mirror survive an 8-g earthquake. The highest risk step in the mirror blank manufacturing process is the near-net-shape CVD deposition of the thin, curved faceplate. Special tooling and procedures had to be developed to produce faceplates free of fractures, cracks, and stress during the cool-down from deposition temperature (1350 C) to room temperature. Due to time delay with the CVD manufacturing process in the meantime a backup solution from Zerodur has been started. This mirror is now in the advanced polishing process. Because the design of both mirrors is very similar an excellent comparison of both solutions is possible.

  5. Synthesis and surface activities of a novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants

    NASA Astrophysics Data System (ADS)

    Geng, Xiang F.; Hu, Xing Q.; Xia, Ji J.; Jia, Xue C.

    2013-04-01

    A series of novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants of 1,2-bis[N-ethyl-N-(2-hydroxyl-3-sulfopropyl)-alkylammonium] alkyl betaines (DBAs-n, where s and n represent the spacer length of 2, 4 and 6 and the hydrocarbon chain length of 8, 12, 14, 16 and 18, respectively) were synthesized by reacting alkylamine with sodium 3-chloro-2-hydroxypropanesulfonate (the alternative sulphonated agent), followed by the reactions with а,ω-dibromoalkyl and then ethyl bromide. Their adsorption and aggregation properties were investigated by means of equilibrium surface tension, dynamic light-scattering (DLS) and transmission electron microscopy (TEM). DBAs-n gemini surfactants showed excellent surface activities and packed tightly at the interface. For example, the minimum CMC value for DBAs-n series was of the order of 10-5 M and the surface tension of water can be decreased as low as 22.2 mN/m. It was also found that the aggregates of DBAs-n solutions were significantly dependent on their hydrocarbon chain lengths. The aggregates changed from vesicles to entangled fiber-like micelles as the chain length increased from dodecyl to tetradecyl.

  6. Adsorption of cationic monomeric and gemini surfactants on montmorillonite and adsolubilization of vitamin E.

    PubMed

    Sakai, Kenichi; Nakajima, Erimi; Takamatsu, Yuichiro; Sharma, Suraj C; Torigoe, Kanjiro; Yoshimura, Tomokazu; Esumi, Kunio; Sakai, Hideki; Abe, Masahiko

    2008-01-01

    Adsorption of a cationic gemini surfactant (1,2-bis(dodecyldimethylammonio) ethane dibromide, 12-2-12) and the corresponding monomeric surfactant (dodecyltrimethylammonium bromide, DTAB) on montmorillonite has been characterized with a combination of adsorption isotherm, interlayer spacing and FT-IR spectroscopic data. Adsolubilization of vitamin E into the adsorbed surfactant layers has also been studied. The adsorption isotherm data reveal that the adsorption of the two surfactants is driven by the two factors: one is the cation exchange that occurs on the interlayer basal planes and the other is the hydrophobic interaction between hydrocarbon chains of the surfactants. Although the adsorbed amount measured in the saturation region (in mol g(-1)) is almost identical for the two surfactants, the conformation of the intercalated surfactant molecules differs significantly from each other. The adsorption of DTAB results in a lateral bilayer arrangement in the limited interlayer space, whereas 12-2-12 gives a normal bilayer arrangement in the expanded interlayer space. Adsolubilization of vitamin E takes place into the adsorbed surfactant layers, and interestingly, all the vitamin E molecules added in the montmorillonite suspensions are hybridized at lower surfactant concentrations due to the great specific surface area of the clay material. Since the maximum adsolubilization amount is usually obtained just below the critical micelle concentration, the gemini surfactant is deemed to be more efficient than the corresponding monomeric one to achieve the great adsolubilization amount.

  7. Mode changes associated with oil droplet movement in solutions of gemini cationic surfactants.

    PubMed

    Banno, Taisuke; Miura, Shingo; Kuroha, Rie; Toyota, Taro

    2013-06-25

    Micrometer-sized self-propelled oil droplets in nonequilibrium systems have attracted much attention, since they form stable emulsions composed of oil, water, and surfactant which represent a primitive type of inanimate chemical machinery. In this work, we examined means of controlling the movement of oil droplets by studying the dynamics of n-heptyloxybenzaldehyde droplets in phosphate buffers containing alkanediyl-α,ω-bis(N-dodecyl-N,N-dimethylammonium bromide) (nG12) with either tetramethylene (4G12), octaethylene (8G12), or dodecamethylene (12G12) chains in the linker moiety. Significant differences in droplet dynamics were observed to be induced by changes in the linker structure of these gemini cationic surfactants. In a phosphate buffer containing 30 mM 4G12, self-propelled motion of droplets concurrent with the formation of molecular aggregates on their surfaces was observed, whereas the fusion of oil droplets was evident in both 8G12 and 12G12 solutions. We also determined that the surface activities and the extent of molecular self-assembly of the surfactants in phosphate buffer were strongly influenced by the alkyl chain length in the linker moiety. We therefore conclude that the surface activities of the gemini cationic surfactant have important effects on the oil-water interfacial tension of oil droplets and the formation of molecular aggregates and that both of these factors induce the unique movement of the droplets.

  8. GeMS: Gemini Mcao System: current status and commissioning plans

    NASA Astrophysics Data System (ADS)

    Boccas, Maxime; Rigaut, François; Gratadour, Damien; d'Orgeville, Céline; Bec, Matthieu; Daruich, Felipe; Perez, Gabriel; Arriagada, Gustavo; Bombino, Stacy; Carter, Chris; Cavedoni, Chas; Collao, Fabian; Collins, Paul; Diaz, Pablo; Ebbers, Angelic; Galvez, Ramon; Gausachs, Gaston; Hardash, Steve; James, Eric; Karewicz, Stan; Lazo, Manuel; Maltes, Diego; Mouser, Ron; Rogers, Rolando; Rojas, Roberto; Sheehan, Michael; Trancho, Gelys; Vergara, Vicente; Vucina, Tomislav

    2008-07-01

    The Gemini Multi-Conjugate Adaptive Optics project was launched in April 1999 to become the Gemini South AO facility in Chile. The system includes 5 laser guide stars, 3 natural guide stars and 3 deformable mirrors optically conjugated at 0, 4.5 and 9km to achieve near-uniform atmospheric compensation over a 1 arc minute square field of view. Sub-contracted systems with vendors were started as early as October 2001 and were all delivered by July 2007, but for the 50W laser (due around September 2008). The in-house development began in January 2006, and is expected to be completed by the end of 2008 to continue with integration and testing (I&T) on the telescope. The on-sky commissioning phase is scheduled to start during the first half of 2009. In this general overview, we will first describe the status of each subsystem with their major requirements, risk areas and achieved performance. Next we will present our plan to complete the project by reviewing the remaining steps through I&T and commissioning on the telescope, both during day-time and at night-time. Finally, we will summarize some management activities like schedules, resources and conclude with some lessons learned.

  9. Gemini J-band observations of RX J0806.4-4123

    NASA Astrophysics Data System (ADS)

    Posselt, B.; Luhman, K. L.

    2016-07-01

    The detection of near-infrared (NIR) excess at the position of a star can indicate either a substellar companion or a disk around the respective star. In this work we probed whether a 2.5σ H-band flux enhancement at the position of the isolated neutron star RX J0806.4-4123 can be confirmed at another NIR wavelength. We observed RX J0806.4-4123 in the J-band with Gemini South equipped with FLAMINGOS-2. There was no significant detection of a J-band source at the neutron star position. However, similarly to the H-band we found a very faint (1.4σ) flux enhancement with a nominal magnitude of J=24.8 ± 0.5. The overall NIR-detection significance is 3.1σ. If real, this emission is too bright to come from the neutron star alone. Deeper near-infrared observations are necessary to confirm or refute the potential NIR excess. The confirmation of such NIR excess could imply that there is a substellar companion or a disk around RX J0806.4-4123. Based on observations obtained at the Gemini Observatory (Program ID: GS-2014B-Q-60) and ESO Paranal Observatory (Program ID: 74.C-0596)

  10. The Gemini NICI planet-finding campaign: The companion detection pipeline

    SciTech Connect

    Wahhaj, Zahed; Liu, Michael C.; Nielsen, Eric L.; Chun, Mark; Ftaclas, Christ; Biller, Beth A.; Close, Laird M.; Hayward, Thomas L.; Hartung, Markus

    2013-12-10

    We present high-contrast image processing techniques used by the Gemini NICI Planet-Finding Campaign to detect faint companions to bright stars. The Near-Infrared Coronographic Imager (NICI) is an adaptive optics instrument installed on the 8 m Gemini South telescope, capable of angular and spectral difference imaging and specifically designed to image exoplanets. The Campaign data pipeline achieves median contrasts of 12.6 mag at 0.''5 and 14.4 mag at 1'' separation, for a sample of 45 stars (V = 4.3-13.9 mag) from the early phase of the campaign. We also present a novel approach to calculating contrast curves for companion detection based on 95% completeness in the recovery of artificial companions injected into the raw data, while accounting for the false-positive rate. We use this technique to select the image processing algorithms that are more successful at recovering faint simulated point sources. We compare our pipeline to the performance of the Locally Optimized Combination of Images (LOCI) algorithm for NICI data and do not find significant improvement with LOCI.

  11. Development of silver coating options for the Gemini 8-m telescopes project

    NASA Astrophysics Data System (ADS)

    Jacobson, Michael R.; Kneale, Ruth C.; Gillett, Fred C.; Raybould, Keith; Filhaber, John M.; Carniglia, Charles K.; Laird, Ronald; Kitchens, Dennis; Shimshock, Ric P.; Booth, Donald C.

    1998-08-01

    Acting as a prime contractor to the Gemini Project, the Optical Data Associates (ODA), with its major subcontractors, BOC Coating Technologies (BOCCT) and Deposition Sciences, Inc. (DSI), developed options for depositing protected silver coatings on the 8-M primary mirrors. The project began with a study that identified sputtering as the preferred deposition technique, defined a set of candidate adhesor and protective coatings for the silver layer, and simulated stack performance. The next phase involved pilot magnetron sputtering studies by BOCCT and DSI of designs involving silicon nitride and hafnia, respectively. ODA also developed mid-IR reflectance standards at (lambda) equals 10.6 micrometers to control the silver coating measurements in the critical 8 - 12 micrometers atmospheric window. The study results were successful, with both BOCCT and DSI producing Ag coatings with R equals 0.9920 +/- 0.0001 and protected Ag coatings with R equals 0.9910 +/- 0.0001. The Gemini Project coating plants are designed to sputter bare and protected Al and Ag coatings.

  12. The Gemini Planet Imager view of the HD 32297 debris disk system

    NASA Astrophysics Data System (ADS)

    Rice, Malena; Hom, Justin; Zalesky, Joe; Duchene, Gaspard; Millar-Blanchaer, Max; Esposito, Thomas; Kalas, Paul; Fitzgerald, Michael P.; GPIES Team

    2017-01-01

    The Gemini Planet Imager (GPI) is a near-infrared imaging instrument used with the Gemini South Telescope in Chile to provide direct imaging and integral field spectroscopy of exoplanetary systems. One of the central goals of the GPI mission is to gain an improved understanding of debris disks, which are remnants of the planet formation process. In this investigation, we present GPI polarimetric observations of the debris disk around the star HD 32297. Previous imaging of the system revealed a nearly edge-on disk that extends into a fan-shaped nebulosity on scales of hundreds of AU. The exquisite quality of total intensity GPI observations, which focus on the inner 150 AU of the disk system, allows us to precisely establish the disk geometry, including evidence for eccentricity in the parent body ring as seen in other such disks. Furthermore, taking advantage of the polarimetric capabilities of GPI, we measure the linear polarization fraction induced by dust scattering. We combine these observations with radiative transfer modeling based on the MCFOST code and using a Markov Chain Monte Carlo (MCMC) method for a thorough and efficient exploration of the parameter space. By simultaneously modeling the GPI scattered light total intensity image, the corresponding polarization fraction map, and the spectral energy distribution of the system, we place constraints on the composition and density structure of the disk. This case study will contribute to an improved understanding of debris disks for the purpose of characterizing planetary system formation and evolution.

  13. GeMini: The Next-Generation Mechanically-Cooled Germanium Spectrometer

    SciTech Connect

    Burks, M

    2008-11-12

    The next-generation mechanically-cooled germanium spectrometer has been developed. GeMini (MINIature GErmanium spectrometer) has been designed to bring high-resolution gamma-ray spectroscopy to a range of demanding field environments. Intended applications include short-notice inspections, border patrol, port monitoring and emergency response, where positive nuclide identification of radioactive materials is required but power and liquid cryogen are not easily available. GeMini weighs 2.75 kg for the basic instrument and 4.5 kg for the full instrument including user interface and ruggedized hermetic packaging. It is very low power allowing it to operate for 10 hours on a single set of rechargeable batteries. This instrument employs technology adapted from the gamma-ray spectrometer currently flying on NASA's Mercury MESSENGER spacecraft. Specifically, infrared shielding techniques allow for a vast reduction of thermal load. This in turn allows for a smaller, lighter-weight design, well-suited for a hand-held instrument. Three working prototypes have been built and tested in the lab. The measured energy resolution is 3 keV fwhm at 662 keV gamma-rays. This paper will focus on the design and performance of the instrument.

  14. GeMini: The Next Generation Mechanically-Cooled Germanium Spectrometer

    SciTech Connect

    Burks, M

    2008-06-13

    The next-generation mechanically-cooled germanium spectrometer has been developed. GeMini (GErmanium MINIature spectrometer) has been designed to bring high-resolution gamma-ray spectroscopy to a range of demanding field environments. Intended applications include short-notice and surprise inspections where positive nuclide identification of radioactive materials is required. GeMini weighs 2.75 kg (6 lbs) total including the detector, cryostat, cryocooler, batteries, electronics and readout. It is very low power allowing it to operate for 10 hours on a single set of rechargeable batteries. This instrument employs technology adapted from the gamma-ray spectrometer currently flying on NASA's Mercury MESSENGER spacecraft. Specifically, infrared shielding techniques allow for a vast reduction of thermal load. This in turn allows for a smaller, lighter-weight design, well-suited for a hand-held instrument. Two working prototypes have been built and tested in the lab. The target energy resolution is 3 keV fwhm or better for 1332 keV gamma-rays. The detectors currently achieve around 4.5 keV resolution, which is slightly higher than our goal due to microphonic noise. Our present work focuses on improving the resolution through mechanical and electronic means of reducing the microphonic noise. This paper will focus on the performance of the instrument and its applicability for inspectors in the field.

  15. The Ages, Metallicities, and Alpha Element Enhancements of Globular Clusters in the Elliptical NGC 5128: A Homogeneous Spectroscopic Study with Gemini/Gemini Multi-Object Spectrograph

    NASA Astrophysics Data System (ADS)

    Woodley, Kristin A.; Harris, William E.; Puzia, Thomas H.; Gómez, Matías; Harris, Gretchen L. H.; Geisler, Doug

    2010-01-01

    We present new integrated light spectroscopy of globular clusters (GCs) in NGC 5128, a nearby giant elliptical galaxy less than 4 Mpc away, in order to measure radial velocities and derive ages, metallicities, and alpha-element abundance ratios. Using the Gemini South 8 meter telescope with the instrument Gemini Multi-Object Spectrograph, we obtained spectroscopy in the range of ~3400-5700 Å for 72 GCs with a signal-to-noise ratio greater than 30 Å-1 and we have also discovered 35 new GCs within NGC 5128 from our radial velocity measurements. We measured and compared the Lick indices from Hδ A through Fe5406 with the single stellar population models of Thomas et al. in order to derive age, metallicity, and [α/Fe] values. We also measure Lick indices for 41 Milky Way GCs from Puzia et al. and Schiavon et al. with the same methodology for direct comparison. Our results show that 68% of the NGC 5128 GCs have old ages (>8 Gyr), 14% have intermediate ages (5-8 Gyr), and 18% have young ages (<5 Gyr). However, when we look at the metallicity of the GCs as a function of age, we find 92% of metal-poor GCs and 56% of metal-rich GCs in NGC 5128 have ages >8 Gyr, indicating that the majority of both metallicity subpopulations of GCs formed earlier, with a significant population of young and metal-rich GCs forming later. Our metallicity distribution function generated directly from spectroscopic Lick indices is clearly bimodal, as is the color distribution of the same set of GCs. Thus, the metallicity bimodality is real and not an artifact of the color to metallicity conversion. However, the metallicity distribution function obtained from comparison with the single stellar population models is consistent with a unimodal, bimodal, or multimodal shape. The [α/Fe] values are supersolar with a mean value of 0.14 ± 0.04, indicating a fast formation timescale. However, the GCs in NGC 5128 are not as [α/Fe] enhanced as the Milky Way GCs also examined in this study. Our measured

  16. Tuning the surface activity of gemini amphiphile by the host-guest interaction of cucurbit[7]uril.

    PubMed

    Wang, Guangtong; Kang, Yuetong; Tang, Bohan; Zhang, Xi

    2015-01-13

    This research is aimed to develop an effective supramolecular route for tuning the surface activity of the surfactant. To this end, cationic gemini amphiphiles and cucurbit[7]uril (CB[7]) were complexed in water, and each hydrophobic chain of the gemini amphiphiles was bound with a CB[7]. The steric hindrance of CB[7] prevented the two hydrophobic chains from getting closed to each other, leading a significant change of surface activity. Before supramolecular complexation, the surface activity of the gemini amphiphile is relatively high, which can generate the foams easily. However, the foam generated by gemini amphiphile can be destructed by adding CB[7], suggesting that the suface activity is lowed after the supramolecular complexation. The surface activity can recover after adding 1-adamantanamine hydrochloride, which has a stronger ability to bind CB[7]. Therefore, a controllable foaming and defoaming process can be realized. It is highly anticipated that supramolecular chemistry for tuning amphiphilicity of surfactants may find application in the fields that fast foaming and defoaming are needed.

  17. Coarse-grained molecular dynamics study on the self-assembly of Gemini surfactants: the effect of spacer length.

    PubMed

    Wang, Pan; Pei, Shuai; Wang, Muhan; Yan, Youguo; Sun, Xiaoli; Zhang, Jun

    2017-02-08

    Gemini surfactants cause a lot of concerns owing to their unusual aggregation morphologies and superior physicochemical properties over the conventional surfactants. Research shows that the unique structure of Gemini surfactants, especially the spacer group, has a great impact on the self-assembly behaviors. To understand the determinants of this behavior on the molecular level, we carried out coarse-grained molecular dynamics (CGMD) simulations on aqueous solutions of alkanediyl-a,w-bis (dimethylcetylammonium bromide)-based surfactants with different spacer group lengths. Our simulation results demonstrated that the self-assembled morphologies of Gemini changed from spherical micelles, wormlike micelles to vesicles with the decrease in the spacer length, which were qualitatively consistent with the experimental observations. Both the microscopic dynamics processes and the self-assembly mechanisms for the formation of spherical micelles, wormlike micelles and vesicles were systematically studied through the CGMD simulations. In addition, based on the microscopic analysis, a strategy was proposed to predict the self-assembled morphology of surfactant-based systems based on simulation. This work shed light on new views in the understanding of the self-assembly of Gemini surfactants at a molecular-level and the proposed predicting strategy showed promise for practical applications.

  18. The influence of novel gemini surfactants containing cycloalkyl side-chains on the structural phases of DNA in solution.

    PubMed

    Pietralik, Zuzanna; Kumita, Janet R; Dobson, Christopher M; Kozak, Maciej

    2015-07-01

    Very important to gene therapy is the delivery system of the nucleic acids (called a vector), which will enhance the efficiency of the transport of new DNA into cells whilst protecting against damage. A promising alternative to the currently used viral vectors are the systems based on amphiphilic compounds - lipoplexes. Among them, gemini surfactants, which consist of two hydrophobic chains and two cationic heads connected by a linker - spacer group, appear to be promising candidates. The subject of this study involves two gemini surfactants, alkoxy derivatives of bis-imidazolium quaternary salts, differing in the length of their spacer groups and how they interact with two types of salmon sperm DNA (low and high molecular weight (MW)) or plasmid DNA (pDNA). The mixtures of gemini surfactants with nucleic acids of differing p/n ratios (positive-to-negative charge ratio) were characterised by small angle X-ray scattering (SAXS) of synchrotron radiation, dynamic light scattering (DLS), circular dichroism (CD) spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and gel electrophoresis techniques. This analysis allows for the selection of the most suitable and promising candidates for non-viral vectors in gene therapy, determination of the conditions needed to form stable complexes, identification of conformational changes in the DNA molecules upon interactions with gemini surfactants and in some cases, determination of the structures formed in these lipoplexes.

  19. Experimenting with Synthesis and Analysis of Cationic Gemini Surfactants in a Second-Semester General Chemistry Laboratory

    ERIC Educational Resources Information Center

    Anzovino, Mary E.; Greenberg, Andrew E.; Moore, John W.

    2015-01-01

    A laboratory experiment is described in which students synthesize a variety of cationic gemini surfactants and analyze their efficacy as fabric softeners. Students perform a simple organic synthesis reaction and two analytical tests (one qualitative and one quantitative), and use the class data to assess the synthesized products. The experiment…

  20. Photoluminescence of CdSe/ZnS core-shell quantum dots stabilized in water with a pseudopeptidic gemini surfactant.

    PubMed

    Rubio, Jenifer; Izquierdo, M Angeles; Burguete, M Isabel; Galindo, Francisco; Luis, Santiago V

    2011-09-01

    The use of pseudopeptidic gemini surfactants as stabilizers of hydrophobic quantum dots in water is discussed. Compound 1a acts as an intercalator with hydrophobic ligands of QDs transferring them from toluene to pure water yielding a fluorescent nanoparticle resistant to quenching by chloride anion (up to 0.1 M).

  1. Surface properties, aggregation behavior and micellization thermodynamics of a class of gemini surfactants with ethyl ammonium headgroups.

    PubMed

    Lu, Ting; Lan, Yuru; Liu, Chenjiang; Huang, Jianbin; Wang, Yilin

    2012-07-01

    Cationic gemini surfactant homologues alkanediyl-α,ω-bis(dodecyldiethylammonium bromide), [C(12)H(25)(CH(3)CH(2))(2)N(CH(2))(S)N(CH(2)CH(3))(2)C(12)H(25)]Br(2) (where S=2, 4, 6, 8, 10, 12, 16, 20), referred to as C(12)C(S)C(12)(Et) were synthesized systematically. This paper focused on various properties of the above gemini surfactants in order to give a full understanding of this series of surfactants. The following points are covered: (1) surface properties, which include (i) effect of the spacer carbon number on the general properties and (ii) the effect of added NaBr on the general surface properties; (2) aggregation behavior in bulk solution, including (i) morphologies of above gemini surfactants classed as having short spacers, middle-length spacers and long spacers and (ii) superior vesicle stability against high NaBr concentration for the long spacer gemini surfactants; (3) thermodynamic properties during micellization and the effect of spacer carbon number on them; and (4) perspectives for the further use and application of these compounds.

  2. 78 FR 40541 - GDT Tek, Inc., Gemini Explorations, Inc., Genetic Vectors, Inc., and Global Gate Property Corp...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-05

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION GDT Tek, Inc., Gemini Explorations, Inc., Genetic Vectors, Inc., and Global Gate Property Corp... accurate information concerning the securities of Genetic Vectors, Inc. because it has not filed...

  3. The 12-3-12 cationic gemini surfactant as a novel gastrointestinal bioadhesive material for improving the oral bioavailability of coenzyme Q10 naked nanocrystals.

    PubMed

    Song, Yanzhi; Han, Jie; Feng, Rui; Wang, Mengjing; Tian, Qingjing; Zhang, Ting; Liu, Xinrong; Cheng, Xiaobo; Deng, Yihui

    2016-12-01

    To improve the oral bioavailability of nanocrystalline drug preparations, the cationic 12-3-12 quaternary ammonium surfactant gemini was introduced into nanocrystals as a novel gastrointestinal bioadhesive material. Coenzyme Q10 (CoQ10), a typical Biopharmaceutics Classification System (BCS) class II drug, was used as a model drug. The 12-3-12 gemini surfactant was added to the preparation at a low concentration and imbued the particles with abundant positive charges. In vitro and in vivo gastrointestinal adhesion tests confirmed that the gemini-modified nanocrystals were prone to adhere to the upper gastrointestinal tract (GIT), thereby prolonging retention time in the GIT and enhancing absorption. In the distribution study in rats, the use of nanocrystals modified with gemini led to greater drug distribution to the heart and the liver than that achieved with the naked nanocrystals. A pharmacokinetic study in beagle dogs showed that the gemini-modified CoQ10 nanocrystals improved the oral bioavailability of CoQ10 in a dose-dependent manner, and the smaller size produced a much better effect with the same gemini modification. These results demonstrate that the cationic surfactant gemini is a promising oral bioadhesive material with applications in nanoscale drug delivery systems.

  4. Triply Periodic Multiply Continuous Lyotropic Liquid Crystals Derived from Gemini Surfactants

    NASA Astrophysics Data System (ADS)

    Sorenson, Gregory P.

    A subtle balance of non-covalent interactions directs the self-assembly of small molecule amphiphiles in aqueous media into supramolecular assemblies known as aqueous lyotropic liquid crystals (LLCs). Aqueous LLCs form many intricate, ordered nanoscale morphologies comprising distinct and structurally periodic hydrophobic and hydrophilic domains. Triply periodic multiply continuous (TPMC) LLC morphologies, which exhibit continuous hydrophobic and aqueous domains that percolate in three-dimensions, are of particular interest by virtue of their potentially wide ranging technological applications including advanced membranes for electrical energy storage and utilization, therapeutic delivery, and templates for new organic and inorganic mesoporous materials. However, robust molecular design criteria for amphiphiles that readily form TMPC morphologies are notably lacking in the literature. Recent reports have described the increased propensity for quaternary ammonium and phosphonium gemini surfactants, derived from dimerization of traditional single-tail surfactants at or near the hydrophilic headgroups through a hydrophobic linker, to stabilize TMPC mesophases. The generality of this surfactant design strategy remains untested in other amphiphiles classes bearing different headgroup chemistries. In this thesis, we describe the unusual aqueous LLC phase behavior of series of gemini dicarboxylate amphiphiles as a function of the alkyl tail length, hydrophobic linker length, and the charge-compensating counterion. These dicarboxylate surfactants unexpectedly exhibit a strong propensity to form TPMC LLCs over amphiphile concentration windows as wide as 20 wt% over a temperature range T = 25--100 °C. Through systematic modifications of the length of the hydrophobic linker and alkyl tails, we use small-angle X-ray scattering to demonstrate that these surfactants adopt new LLC mesophases including the first report of a single-gyroid phase (I4132 symmetry) and a new

  5. SUBARU AND GEMINI OBSERVATIONS OF SS 433: NEW CONSTRAINT ON THE MASS OF THE COMPACT OBJECT

    SciTech Connect

    Kubota, K.; Ueda, Y.; Fabrika, S.; Barsukova, E. A.; Sholukhova, O.; Medvedev, A.; Goranskij, V. P.

    2010-02-01

    We present results of optical spectroscopic observations of the mass donor star in SS 433 with Subaru and Gemini, with an aim to best constrain the mass of the compact object. Subaru/Faint Object Camera and Spectrograph observations were performed on four nights of 2007 October 6-8 and 10, covering the orbital phase of phi = 0.96 - 0.26. We first calculate the cross-correlation function (CCF) of these spectra with that of the reference star HD 9233 in the wavelength range of 4740-4840 A. This region is selected to avoid 'strong' absorption lines accompanied with contaminating emission components, which most probably originate from the surroundings of the donor star, such as the wind and gas stream. The same analysis is applied to archive data of Gemini/GMOS taken at phi = 0.84 - 0.30 by Hillwig and Gies. From the Subaru and Gemini CCF results, the amplitude of the radial velocity curve of the donor star is determined to be 58.3 +- 3.8 km s{sup -1} with a systemic velocity of 59.2 +- 2.5 km s{sup -1}. Together with the radial velocity curve of the compact object, we derive the mass of the donor star and compact object to be M{sub O} = 12.4 +- 1.9 M{sub sun} and M{sub X} = 4.3 +- 0.6 M{sub sun}, respectively. We conclude, however, that these values should be taken as upper limits. From the analysis of the averaged absorption line profiles of strong lines (mostly ions) and weak lines (mostly neutrals) observed with Subaru, we find evidence for heating effects from the compact object. Using a simple model, we find that the true radial velocity amplitude of the donor star could be as low as 40 +- 5 km s{sup -1} in order to produce the observed absorption-line profiles. Taking into account the heating of the donor star may lower the derived masses to M{sub O} = 10.4{sup +2.3}{sub -1.9} M{sub sun} and M{sub X} = 2.5{sup +0.7}{sub -0.6} M{sub sun}. Our final constraint, 1.9 M{sub sun} <=M{sub X}<= 4.9 M{sub sun}, indicates that the compact object in SS 433 is most likely a

  6. The Gemini NICI planet-finding campaign: The offset ring of HR 4796 A

    NASA Astrophysics Data System (ADS)

    Wahhaj, Zahed; Liu, Michael C.; Biller, Beth A.; Nielsen, Eric L.; Hayward, Thomas L.; Kuchner, Marc; Close, Laird M.; Chun, Mark; Ftaclas, Christ; Toomey, Douglas W.

    2014-07-01

    We present J,H, CH4 short (1.578 μm), CH4 long (1.652 μm) and Ks-band images of the dust ring around the 10 Myr old star HR 4796 A obtained using the Near Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1 m Telescope. Our images clearly show for the first time the position of the star relative to its circumstellar ring thanks to NICI's translucent focal plane occulting mask. We employ a Bayesian Markov chain Monte Carlo method to constrain the offset vector between the two. The resulting probability distribution shows that the ring center is offset from the star by 16.7 ± 1.3 milliarcseconds along a position angle of 26 ± 3°, along the PA of the ring, 26.47 ± 0.04°. We find that the size of this offset is not large enough to explain the brightness asymmetry of the ring. The ring is measured to have mostly red reflectivity across the JHKs filters, which seems to indicate micron-sized grains. Just like Neptune's 3:2 and 2:1 mean-motion resonances delineate the inner and outer edges of the classical Kuiper belt, we find that the radial extent of the HR 4796 A and the Fomalhaut rings could correspond to the 3:2 and 2:1 mean-motion resonances of hypothetical planets at 54.7 AU and 97.7 AU in the two systems, respectively. A planet orbiting HR 4796 A at 54.7 AU would have to be less massive than 1.6 MJup so as not to widen the ring too much by stirring. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).Tables 5 and 6 are available in electronic form at

  7. Spontaneous formation of nanocubic particles and spherical vesicles in catanionic mixtures of ester-containing gemini surfactants and sodium dodecyl sulfate in the presence of electrolyte.

    PubMed

    Aghdastinat, Hasti; Javadian, Soheila; Tehrani-Bagha, Alireza; Gharibi, Hussein

    2014-03-20

    Self-assembly of pure ester-containing cationic gemini surfactants, dodecyl esterquat, and dodecyl betainate geminis, and cation-rich catanionic mixtures of them with sodium dodecyl sulfate (SDS) were investigated using surface tension, electrical conductivity, dynamic light scattering (DLS), transmission electron microscopy (TEM) and cyclic voltammetry (CV) measurements in the absence and presence of KCl. Different physicochemical properties such as the critical micelle concentration (CMC), degree of counterion dissociation (αdiss), interfacial properties, morphology of aggregates, and interparticle interaction parameters were determined. Both geminis formed micelles in the absence of KCl, and mixing with SDS did not change the morphology; just a growth in micelle size was observed. However, the aggregation behavior of these geminis with respect to the position of the ester bond in the alkyl chain appeared completely different in the presence of KCl. Esterquat gemini formed cubic nanoparticles (or cobosomes) in the presence of [KCl] = 0.05 M and transformed into spherical micelles upon increasing the surfactant concentration. By contrast, betainate gemini formed vesicles in the presence of [KCl] = 0.05 M and subsequently converted to micelles as the surfactant concentration increased. The morphology of esterquat gemini (in the presence of 0.05 M KCl) after mixing with SDS changed from cubic nanoparticles (or cobosomes) to cylindrical nanoparticles coexistent with cobosomes. Betainate gemini remained vesicular upon mixing with SDS, and no dramatic structural change of aggregates took place. The morphology changes of aggregates upon mixing with SDS were explained from calculating the interactions between two gemini surfactants and SDS on the basis of regular solution theory.

  8. Efficacious gene silencing in serum and significant apoptotic activity induction by survivin downregulation mediated by new cationic gemini tocopheryl lipids.

    PubMed

    Kumar, Krishan; Maiti, Bappa; Kondaiah, Paturu; Bhattacharya, Santanu

    2015-02-02

    Nonviral gene delivery offers cationic liposomes as promising instruments for the delivery of double-stranded RNA (ds RNA) molecules for successful sequence-specific gene silencing (RNA interference). The efficient delivery of siRNA (small interfering RNA) to cells while avoiding unexpected side effects is an important prerequisite for the exploitation of the power of this excellent tool. We present here six new tocopherol based cationic gemini lipids, which induce substantial gene knockdown without any obvious cytotoxicity. All the efficient coliposomal formulations derived from each of these geminis and a helper lipid, dioleoylphosphatidylethanolamine (DOPE), were well characterized using physical methods such as atomic force microscopy (AFM) and dynamic light scattering (DLS). Zeta potential measurements were conducted to estimate the surface charge of these formulations. Flow cytometric analysis showed that the optimized coliposomal formulations could transfect anti-GFP siRNA efficiently in three different GFP expressing cell lines, viz., HEK 293T, HeLa, and Caco-2, significantly better than a potent commercial standard Lipofectamine 2000 (L2K) both in the absence and in the presence of serum (FBS). Notably, the knockdown activity of coliposomes of gemini lipids was not affected even in the presence of serum (10% and 50% FBS) while it dropped down for L2K significantly. Observations under a fluorescence microscope, RT-PCR, and Western blot analysis substantiated the flow cytometry results. The efficient cellular entry of labeled siRNA in GFP expressing cells as evidenced from confocal microscopy put forward these gemini lipids among the potent lipidic carriers for siRNA. The efficient transfection capabilities were also profiled in a more relevant fashion while performing siRNA transfections against survivin (an anti-apoptotic protein) which induced substantial apoptosis. Furthermore, the survivin downregulation improved the therapeutic efficacy levels of an

  9. Rejecting harmonic vibrations at Gemini with real-time vibration tracking

    NASA Astrophysics Data System (ADS)

    Rippa, Mathew J.; Bonnet, Henri; Hayward, Thomas L.; Trujillo, Chadwick; Cavedoni, Chas P.; Cumming, Tom; Yamasaki, Chris; Masuda, Neal; Bagano, Cy; Hardash, Steve

    2016-08-01

    Fighting vibrations on large telescopes is an arduous task. At Gemini, vibrations originating from cryogenic coolers have been shown to degrade the optical wavefront, in certain cases by as much as 40%. This paper discusses a general solution to vibration compensation by tracking the real time vibration state of the telescope and using M2 to apply corrections. Two approaches are then presented: an open loop compensation at M2 based on the signal of accelerometers at the M1 glass, and a closed loop compensation at M2 based on optical measurements from the wave front sensor. The paper elaborates on the pros and cons of each approach and the challenges faced during commissioning. A conclusion is presented with the final results of vibration tracking integrated with operations.

  10. The first two years of the Gemini Fast Turnaround Proposal Program

    NASA Astrophysics Data System (ADS)

    Andersen, Morten; Mason, Rachel; Geballe, Thomas R.; Chiboucas, Kristin; Salinas, Ricardo; Lundquist, Michael J.; scharwaechter, Julia; Schirmer, Mischa; silva, Karleyene

    2017-01-01

    Gemini Observatory has since February 2015 offered telescope time monthly through the Fast Turnaround observing route. A fast review process by the proposers themselves coupled with rapid scheduling allow the proposals to go from submission to part of the queue in a month and the observations are then active for 3 months, much faster than the traditional semester based proposal scheme.Both telescopes are included and around 10% of the available telescope time is allocated each month.Here we present the early results and lessons learned from the program. We discuss the over-subscription, the review process and the selection of proposals as well as the scheduling. The completion rates is further discussed. Finally we highlight some of the science results coming out of the program.

  11. UNVEILING THE NEW GENERATION OF STARS IN NGC 604 WITH GEMINI-NIRI

    SciTech Connect

    Farina, Cecilia; Bosch, Guillermo L.

    2012-02-15

    We present a near-infrared study focused on the detection and characterization of the youngest stellar component of the NGC 604 giant star-forming region in the Triangulum galaxy (M 33). By means of color-color diagrams derived from the photometry of JHK{sub s} images taken with the Gemini Near Infrared Imaging and Spectrometer (NIRI), we have found 68 candidate massive young stellar objects. The spatial distribution of these sources matches the areas where previous studies suggested that star formation might be taking place, and the high spatial resolution of our deep NIRI imaging allows us to pinpoint the star-forming knots. An analysis of the fraction of objects that show infrared excess suggests that the star formation is still active, supporting the presence of a second generation of stars being born, although the evidence for or against sequential star formation does not seem to be conclusive.

  12. Gemini H-band spectroscopy of the Galactic microquasar GRS 1915+105

    NASA Astrophysics Data System (ADS)

    McConnell, O.; Callanan, P.; Reynolds, M.

    2014-07-01

    Since its discovery in 1994 (Castro-Tirado 1994) GRS 1915+105 has become one of the most intensely studied of all the X-ray binaries in the Galaxy. This Galactic microquasar system is unique in that it has remained in outburst for the past 20 years: furthermore, initial measurements suggested a relatively high black hole mass of 14 ± 4 M_{⊙} (Greiner et al. 2001), outside the predicted mass range for such transients (Ozel et al. 2010). Here we present new Gemini H-band observations, and discuss the degree to which they can be used to refine the black hole mass in comparison to more recent estimates (Hurley et al 2013, Steeghs et al 2013). In addition, previous work found phase dependent emission of the CO bandheads in the K-band, and we present evidence of double peaked emission lines, indicative of ongoing mass transfer via the accretion disk.

  13. Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager

    SciTech Connect

    Macintosh, B.; Graham, J. R.; Barman, T.; De Rosa, R. J.; Konopacky, Q.; Marley, M. S.; Marois, C.; Nielsen, E. L.; Pueyo, L.; Rajan, A.; Rameau, J.; Saumon, D.; Wang, J. J.; Patience, J.; Ammons, M.; Arriaga, P.; Artigau, E.; Beckwith, S.; Brewster, J.; Bruzzone, S.; Bulger, J.; Burningham, B.; Burrows, A. S.; Chen, C.; Chiang, E.; Chilcote, J. K.; Dawson, R. I.; Dong, R.; Doyon, R.; Draper, Z. H.; Duchene, G.; Esposito, T. M.; Fabrycky, D.; Fitzgerald, M. P.; Follette, K. B.; Fortney, J. J.; Gerard, B.; Goodsell, S.; Greenbaum, A. Z.; Hibon, P.; Hinkley, S.; Cotten, T. H.; Hung, L. -W.; Ingraham, P.; Johnson-Groh, M.; Kalas, P.; Lafreniere, D.; Larkin, J. E.; Lee, J.; Line, M.; Long, D.; Maire, J.; Marchis, F.; Matthews, B. C.; Max, C. E.; Metchev, S.; Millar-Blanchaer, M. A.; Mittal, T.; Morley, C. V.; Morzinski, K. M.; Murray-Clay, R.; Oppenheimer, R.; Palmer, D. W.; Patel, R.; Perrin, M. D.; Poyneer, L. A.; Rafikov, R. R.; Rantakyro, F. T.; Rice, E. L.; Rojo, P.; Rudy, A. R.; Ruffio, J. -B.; Ruiz, M. T.; Sadakuni, N.; Saddlemyer, L.; Salama, M.; Savransky, D.; Schneider, A. C.; Sivaramakrishnan, A.; Song, I.; Soummer, R.; Thomas, S.; Vasisht, G.; Wallace, J. K.; Ward-Duong, K.; Wiktorowicz, S. J.; Wolff, S. G.; Zuckerman, B.

    2015-10-02

    Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10–6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, “hot-start” formation models indicate a mass twice that of Jupiter. As a result, this planet also has a sufficiently low luminosity to be consistent with the “cold-start” core-accretion process that may have formed Jupiter.

  14. Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager

    DOE PAGES

    Macintosh, B.; Graham, J. R.; Barman, T.; ...

    2015-10-02

    Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10–6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, “hot-start” formation models indicate a mass twicemore » that of Jupiter. As a result, this planet also has a sufficiently low luminosity to be consistent with the “cold-start” core-accretion process that may have formed Jupiter.« less

  15. Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager.

    PubMed

    Macintosh, B; Graham, J R; Barman, T; De Rosa, R J; Konopacky, Q; Marley, M S; Marois, C; Nielsen, E L; Pueyo, L; Rajan, A; Rameau, J; Saumon, D; Wang, J J; Patience, J; Ammons, M; Arriaga, P; Artigau, E; Beckwith, S; Brewster, J; Bruzzone, S; Bulger, J; Burningham, B; Burrows, A S; Chen, C; Chiang, E; Chilcote, J K; Dawson, R I; Dong, R; Doyon, R; Draper, Z H; Duchêne, G; Esposito, T M; Fabrycky, D; Fitzgerald, M P; Follette, K B; Fortney, J J; Gerard, B; Goodsell, S; Greenbaum, A Z; Hibon, P; Hinkley, S; Cotten, T H; Hung, L-W; Ingraham, P; Johnson-Groh, M; Kalas, P; Lafreniere, D; Larkin, J E; Lee, J; Line, M; Long, D; Maire, J; Marchis, F; Matthews, B C; Max, C E; Metchev, S; Millar-Blanchaer, M A; Mittal, T; Morley, C V; Morzinski, K M; Murray-Clay, R; Oppenheimer, R; Palmer, D W; Patel, R; Perrin, M D; Poyneer, L A; Rafikov, R R; Rantakyrö, F T; Rice, E L; Rojo, P; Rudy, A R; Ruffio, J-B; Ruiz, M T; Sadakuni, N; Saddlemyer, L; Salama, M; Savransky, D; Schneider, A C; Sivaramakrishnan, A; Song, I; Soummer, R; Thomas, S; Vasisht, G; Wallace, J K; Ward-Duong, K; Wiktorowicz, S J; Wolff, S G; Zuckerman, B

    2015-10-02

    Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10(-6) and an effective temperature of 600 to 750 kelvin. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold-start" core-accretion process that may have formed Jupiter.

  16. Gemini Planet Imager Spectroscopy of the HR 8799 Planets c and d

    DOE PAGES

    Ingraham, Patrick; Marley, Mark S.; Saumon, Didier; ...

    2014-09-30

    During the first-light run of the Gemini Planet Imager we obtained K-band spectra of exoplanets HR 8799 c and d. Analysis of the spectra indicates that planet d may be warmer than planet c. Comparisons to recent patchy cloud models and previously obtained observations over multiple wavelengths confirm that thick clouds combined with horizontal variation in the cloud cover generally reproduce the planets’ spectral energy distributions.When combined with the 3 to 4μm photometric data points, the observations provide strong constraints on the atmospheric methane content for both planets. Lastly, the data also provide further evidence that future modeling efforts mustmore » include cloud opacity, possibly including cloud holes, disequilibrium chemistry, and super-solar metallicity.« less

  17. GE-mini: a mobile APP for large-scale gene expression visualization.

    PubMed

    Tang, Zefang; Li, Chenwei; Zhang, Karena; Yang, Mingyu; Hu, Xueda

    2017-01-08

    The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) projects produced large-scale RNA sequencing data, which provides an opportunity for performing integrated expression analysis for all genes across tens of thousands of tumor and normal tissue specimens. Rapid access to and easy visualization of such valuable data could facilitate research in a wide biological area. Here, we present the GE-mini APP for smart phones, a mobile visualization tool for integrated gene expression data based on both TCGA and GTEx. This gene-centric expression viewer provides a convenient method for displaying expression profiles of all available tumor and tissue types, while allowing drilling down to detailed views for specific tissue types.

  18. Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Macintosh, B.; Graham, J. R.; Barman, T.; De Rosa, R. J.; Konopacky, Q.; Marley, M. S.; Marois, C.; Nielsen, E. L.; Pueyo, L.; Rajan, A.; Rameau, J.; Saumon, D.; Wang, J. J.; Patience, J.; Ammons, M.; Arriaga, P.; Artigau, E.; Beckwith, S.; Brewster, J.; Bruzzone, S.; Bulger, J.; Burningham, B.; Burrows, A. S.; Chen, C.; Chiang, E.; Chilcote, J. K.; Dawson, R. I.; Dong, R.; Doyon, R.; Draper, Z. H.; Duchêne, G.; Esposito, T. M.; Fabrycky, D.; Fitzgerald, M. P.; Follette, K. B.; Fortney, J. J.; Gerard, B.; Goodsell, S.; Greenbaum, A. Z.; Hibon, P.; Hinkley, S.; Cotten, T. H.; Hung, L.-W.; Ingraham, P.; Johnson-Groh, M.; Kalas, P.; Lafreniere, D.; Larkin, J. E.; Lee, J.; Line, M.; Long, D.; Maire, J.; Marchis, F.; Matthews, B. C.; Max, C. E.; Metchev, S.; Millar-Blanchaer, M. A.; Mittal, T.; Morley, C. V.; Morzinski, K. M.; Murray-Clay, R.; Oppenheimer, R.; Palmer, D. W.; Patel, R.; Perrin, M. D.; Poyneer, L. A.; Rafikov, R. R.; Rantakyrö, F. T.; Rice, E. L.; Rojo, P.; Rudy, A. R.; Ruffio, J.-B.; Ruiz, M. T.; Sadakuni, N.; Saddlemyer, L.; Salama, M.; Savransky, D.; Schneider, A. C.; Sivaramakrishnan, A.; Song, I.; Soummer, R.; Thomas, S.; Vasisht, G.; Wallace, J. K.; Ward-Duong, K.; Wiktorowicz, S. J.; Wolff, S. G.; Zuckerman, B.

    2015-10-01

    Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10-6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, “hot-start” formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the “cold-start” core-accretion process that may have formed Jupiter.

  19. Tracking Publications Based on Telescope Sharing among Gemini, Subaru, and Keck: An Update

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Tsang, E.; Kamisato, P.

    2015-04-01

    Gemini Observatory, Subaru Telescope, and Keck Observatory collectively operate five 8-10 meters telescopes on the summit of Mauna Kea on the Island of Hawaii and at Cerro Pachon in Chile. The three institutions began a telescope exchange program in 2005 to expand the range of backend instruments available to their respective users. A participating observatory's users can apply for telescope time from the other two observatories through the time exchange program. To measure the success of the program, we collected publications that resulted from the exchange program for the period from 2005 to 2013. Bibliometric analysis was performed on these publications to measure the productivity and impact of the exchange program. This is an enhanced and updated version of the paper presented at the IAU Commission 5 working Group Libraries session in Beijing, 2012.

  20. Gemini Planet Imager Spectroscopy of the HR 8799 Planets c and d

    NASA Astrophysics Data System (ADS)

    Ingraham, Patrick; Marley, Mark S.; Saumon, Didier; Marois, Christian; Macintosh, Bruce; Barman, Travis; Bauman, Brian; Burrows, Adam; Chilcote, Jeffrey K.; De Rosa, Robert J.; Dillon, Daren; Doyon, René; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Gavel, Donald; Goodsell, Stephen J.; Graham, James R.; Hartung, Markus; Hibon, Pascale; Kalas, Paul G.; Konopacky, Quinn; Larkin, James A.; Maire, Jérôme; Marchis, Franck; McBride, James; Millar-Blanchaer, Max; Morzinski, Katie M.; Norton, Andrew; Oppenheimer, Rebecca; Palmer, Dave W.; Patience, Jenny; Perrin, Marshall D.; Poyneer, Lisa A.; Pueyo, Laurent; Rantakyrö, Fredrik; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Soummer, Rémi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2014-10-01

    During the first-light run of the Gemini Planet Imager we obtained K-band spectra of exoplanets HR 8799 c and d. Analysis of the spectra indicates that planet d may be warmer than planet c. Comparisons to recent patchy cloud models and previously obtained observations over multiple wavelengths confirm that thick clouds combined with horizontal variation in the cloud cover generally reproduce the planets' spectral energy distributions. When combined with the 3 to 4 μm photometric data points, the observations provide strong constraints on the atmospheric methane content for both planets. The data also provide further evidence that future modeling efforts must include cloud opacity, possibly including cloud holes, disequilibrium chemistry, and super-solar metallicity.

  1. Gemini Planet Imager Spectroscopy of the HR 8799 Planets c and d

    SciTech Connect

    Ingraham, Patrick; Marley, Mark S.; Saumon, Didier; Marois, Christian; Macintosh, Bruce; Barman, Travis; Bauman, Brian; Burrows, Adam; Chilcote, Jeffrey K.; De Rosa, Robert J.; Dillon, Daren; Doyon, René; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Gavel, Donald; Goodsell, Stephen J.; Graham, James R.; Hartung, Markus; Hibon, Pascale; Kalas, Paul G.; Konopacky, Quinn; Larkin, James A.; Marchis, Franck; McBride, James; Millar-Blanchaer, Max; Morzinski, Katie M.; Norton, Andrew; Oppenheimer, Rebecca; Palmer, Dave W.; Patience, Jenny; Perrin, Marshall D.; Poyneer, Lisa A.; Pueyo, Laurent; Rantakyrö, Fredrik; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Soummer, Rémi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Kent Wallace, J.; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2014-09-30

    During the first-light run of the Gemini Planet Imager we obtained K-band spectra of exoplanets HR 8799 c and d. Analysis of the spectra indicates that planet d may be warmer than planet c. Comparisons to recent patchy cloud models and previously obtained observations over multiple wavelengths confirm that thick clouds combined with horizontal variation in the cloud cover generally reproduce the planets’ spectral energy distributions.When combined with the 3 to 4μm photometric data points, the observations provide strong constraints on the atmospheric methane content for both planets. Lastly, the data also provide further evidence that future modeling efforts must include cloud opacity, possibly including cloud holes, disequilibrium chemistry, and super-solar metallicity.

  2. GEMINI PLANET IMAGER SPECTROSCOPY OF THE HR 8799 PLANETS c AND d

    SciTech Connect

    Ingraham, Patrick; Macintosh, Bruce; Marley, Mark S.; Saumon, Didier; Marois, Christian; Dunn, Jennifer; Erikson, Darren; Barman, Travis; Bauman, Brian; Burrows, Adam; Chilcote, Jeffrey K.; Fitzgerald, Michael P.; De Rosa, Robert J.; Dillon, Daren; Gavel, Donald; Doyon, René; Goodsell, Stephen J.; Hartung, Markus; Hibon, Pascale; Graham, James R.; and others

    2014-10-10

    During the first-light run of the Gemini Planet Imager we obtained K-band spectra of exoplanets HR 8799 c and d. Analysis of the spectra indicates that planet d may be warmer than planet c. Comparisons to recent patchy cloud models and previously obtained observations over multiple wavelengths confirm that thick clouds combined with horizontal variation in the cloud cover generally reproduce the planets' spectral energy distributions. When combined with the 3 to 4 μm photometric data points, the observations provide strong constraints on the atmospheric methane content for both planets. The data also provide further evidence that future modeling efforts must include cloud opacity, possibly including cloud holes, disequilibrium chemistry, and super-solar metallicity.

  3. Direct observation of extrasolar planets and the development of the gemini planet imager integral field spectrograph

    NASA Astrophysics Data System (ADS)

    Chilcote, Jeffrey Kaplan

    This thesis is focused on the development and testing of a new instrument capable of finding and characterizing recently-formed Jupiter-sized planets orbiting other stars. To observe these planets, I present the design, construction and testing of the Gemini Planet Imager (GPI) Integral Field Spectrograph (IFS). GPI is a facility class instrument for the Gemini Observatory with the primary goal of directly detecting young Jovian planets. The GPI IFS utilizes an infrared transmissive lenslet array to sample a rectangular 2.7 x 2.7 arcsecond field of view and provide low-resolution spectra across five bands between 1 and 2.5 mum. The dispersing element can be replaced with a Wollaston prism to provide broadband polarimetry across the same five filter bands. The IFS construction was based at the University of California, Los Angeles in collaboration with the Universite de Montreal, Immervision and Lawrence Livermore National Laboratory. I will present performance results, from in-lab testing, of the Integral Field Spectrograph (IFS) for the Gemini Planet Imager (GPI). The IFS is a large, complex, cryogenic, optical system requiring several years of development and testing. I will present the design and integration of the mechanical and optical performance of the spectrograph optics. The IFS passed its pre-ship review in 2011 and was shipped to University of California, Santa Cruz for integration with the remaining sub-systems of GPI. The UCLA built GPI IFS was integrated with the rest of GPI and is delivering high quality spectral datacubes of GPI's coronagraphic field. Using the NIRC2 instrument located at the Keck Observatory, my collaborators and I observed the planetary companion to beta Pictoris in L' (3.5--4.1mum). Observations taken in the fall of 2009 and 2012 are used to find the location and inclination of the planet relative to the massive debris disk orbiting beta Pictoris. We find that the planet's orbit has a position angle on the sky of 211

  4. Tracking Publications Based on Telescope Sharing Among Gemini, Subaru, and Keck

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Tsang, E.; Kamisato, P.

    2012-08-01

    Gemini Observatory, Subaru Telescope and Keck Observatory operate five 8-10 meters telescopes on the summit of Mauna Kea on the Island of Hawaii and Cerro Pachon in Chile. To expand the range of backend instruments available to each observatory, the three institutions began an exchange program in 2005, whereby each observatory provides a fraction of its telescope time to users of the other two observatories in exchange for telescope time on these telescopes for its own user community. Publications resulted from such collaborations would be a good measure of the success of the program. However, identifying these publications can be a challenge as explicit acknowledgement of the exchange programs are often lacking in some publications. We discuss procedures in identifying exchange publications and also perform bibliometric analysis with the resulting publications as a way to measure the productivity and impact of the exchange programs.

  5. Monomeric and gemini surfactants as antimicrobial agents - influence on environmental and reference strains.

    PubMed

    Koziróg, Anna; Brycki, Bogumił

    2015-01-01

    Quaternary ammonium salts (QAS) belong to surfactant commonly used both, in the household and in different branches of industry, primarily in the process of cleaning and disinfection. They have several positive features inter alia effectively limiting the development of microorganisms on many surfaces. In the present work, two compounds were used as biocides: hexamethylene-1,6-bis-(N,N-dimethyl-N-dodecylammonium bromide) that belongs to the gemini surfactant (GS), and its single analogue - dodecyl(trimethyl)ammonium bromide (DTAB). Two fold dilution method was used to determine the minimum concentration of compounds (MIC) which inhibit the growth of bacteria: Staphylococcus aureus (ATCC 6538 and an environmental strain), Pseudomonas aeruginosa (ATCC 85327 and an environmental strain), and yeast Candida albicans (ATCC 11509 and an environmental strain). The viability of cells in liquid cultures with addition of these substances at ¼ MIC, ½ MIC and MIC concentrations were also determined. The obtained results show that DTAB inhibits the growth of bacteria at the concentration of 0.126-1.010 µM/ml, and gemini surfactant is active at 0.036-0.029 µM/ml. Therefore, GS is active at more than 17-70-fold lower concentrations than its monomeric analogue. Strains isolated from natural environment are less sensitive upon testing biocides than the references strains. Both compounds at the MIC value reduced the number of cells of all strains. The use of too low concentration of biocides can limit the growth of microorganisms, but often only for a short period of time in case of special environmental strains. Later on, they can adapt to adverse environmental conditions and begin to evolve defence mechanisms.

  6. Aqueous Two-Phase System (ATPS) Containing Gemini (12-3-12,2Br-)and SDS 1: Phase Diagram and Properties of ATPS

    SciTech Connect

    Shang, Yazhuo; Liu, Honglai; Hu, Ying; Prausnitz, John M.

    2005-07-21

    Two phases coexist in an aqueous system that contains the two surfactants cationic gemini 12-3-12,2Br- and anionic SDS. An aqueous two-phase system (ATPS) is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic-anionic surfactant systems. In that region, the molar ratio of gemini to SDS varies with the total concentration of surfactants. ATPS not only has higher stability but also has longer phase separation time for the new systems than that of the traditional system. Furthermore, the optical properties of ATPS are different at different total concentrations. All of these experimental observations can be attributed to the unique properties of gemini surfactant and the synergy between the cationic gemini surfactant and the anionic surfactant SDS.

  7. Thiol-responsive gemini poly(ethylene glycol)-poly(lactide) with a cystine disulfide spacer as an intracellular drug delivery nanocarrier.

    PubMed

    Kim, Hyun-Chul; Kim, Eunjoo; Ha, Tae-Lin; Jeong, Sang Won; Lee, Se Guen; Lee, Sung Jun; Lee, Boram

    2015-03-01

    Thiol-responsive gemini micelles consisting of hydrophilic poly(ethylene glycol) (PEG) blocks and hydrophobic polylactide (PLA) blocks with a cystine disulfide spacer were reported as effective intracellular nanocarriers of drugs. In the presence of cellular glutathione (GSH) as a reducing agent, gemini micelles gradually destabilize into monomeric micelles through cleavage of the cystine linkage. This destabilization of the gemini micelles changed their size distribution, with the appearance of small aggregates, and led to the enhanced release of encapsulated doxorubicin (DOX). The results obtained from cell culture via confocal laser scanning microscopy (CLSM) for cellular uptake, as well as cell viability measurements for anticancer efficacy suggest the potential of disulfide-based gemini polymeric micelles as controlled drug delivery carriers.

  8. Interplay between hydrophilic and hydrophobic interactions in the self-assembly of a gemini amphiphilic pseudopeptide: from nano-spheres to hydrogels.

    PubMed

    Rubio, Jenifer; Alfonso, Ignacio; Burguete, M Isabel; Luis, Santiago V

    2012-02-21

    The formation of soluble nano-spheres or stable hydrogels through the self-assembling of a simple gemini amphiphilic pseudopeptide can be controlled by the tuning of the hydrophilic/hydrophobic interactions in aqueous medium.

  9. A DSC investigation on the influence of gemini surfactant stereochemistry on the organization of lipoplexes and on their interaction with model membranes.

    PubMed

    Aleandri, S; Bonicelli, M G; Giansanti, L; Giuliani, C; Ierino, M; Mancini, G; Martino, A; Scipioni, A

    2012-12-01

    Previous investigations showed that the extent of DNA condensation and the efficiency in the transfection of liposomes formulated with 1,2-dimyristoyl-sn-glycero-phosphocholine and cationic stereomeric gemini surfactants depend heavily on the stereochemistry of the gemini. The influence of the stereochemistry on the interaction of lipoplexes with zwitterionic and anionic cell membrane models was investigated by differential scanning calorimetry to rationalize their different biological behavior. Further, the thermotropic behavior of the corresponding liposomes and of the spontaneous self-assemblies of gemini surfactants in the presence and in the absence of DNA was evaluated to correlate the physicochemical properties of lipoplexes and the stereochemistry of the cationic component. The obtained results show that the stereochemistry of the gemini surfactant controls lipoplexes organization and their mode and kinetic of interaction with different cell membrane models.

  10. Tandem mass spectrometric analysis of novel diquaternary ammonium gemini surfactants and their bromide adducts in electrospray-positive ion mode ionization.

    PubMed

    Buse, Joshua; Badea, Ildiko; Verrall, Ronald E; El-Aneed, Anas

    2011-10-01

    Gemini surfactants are cationic lipids which are utilized for both in vitro and in vivo gene delivery. Structurally, they are comprised of two hydrophobic tail regions with polar head termini that are attached to one another through a spacer region. Structural elucidation and characterization of 29 novel diquaternary ammonium gemini surfactant molecules were achieved using a quadrupole time-of-flight mass spectrometer (QqToF-MS) and a quadrupole-hexapole-quadrupole mass spectrometer (QhQ-MS). The tested compounds were categorized into four distinct structural families based upon the composition of the spacer region. Single stage (MS), tandem stage (MS/MS) and quasimulti-stage (quasi MS(3)) mass spectrometric analysis allowed for confirmation of each gemini surfactant's molecular composition and structure through the identification of common and unique product ions. Identification of similarities in the gemini surfactants' fragmentation behaviour resulted in the production of a universal fragmentation pathway that can assist in the future MS/MS analysis of novel quaternary ammonium gemini surfactants, with unique product ions being indicative of specific structural elements. Furthermore, evidence for the association of agemini surfactant with bromine counter ion was confirmed during MS analysis of tested gemini surfactants regardless of their chemical composition; previously, evidence for bromine and gemini surfactant association was only observed with compounds bearing short alkyl spacer regions. MS/MS analysis of the bromine adducts was also confirmatory to the molecular structure.Understanding the ionization and fragmentation behaviour of gemini surfactants, including bromine adducts, will allow for future qualitative and quantitative identification of these novel drug delivery agents within biological samples.

  11. [Results obtained from more intensive antenatal and intranatal attention to gemini pregnancy at gynaecological hospital of Karl-Marx-Stadt region (author's transl)].

    PubMed

    Schmidt, J; Cimutta, B; Müller, K

    1979-01-01

    Studies undertaken into gemini births between 1968 and 1977 have shown that reduction in perinatal mortality has been obtainable from high-intensity programmes of antenatal and intranatal attention to multiparae. Perinatal mortality had accounted for 13.4 per cent, between 1968 and 1974, and dropped to 7.4 per cent, between 1975 and 1977. This achievement is analysed and discussed. More improvement may best be expected from earlier detection of gemini pregnancy and earlier action of intensive care.

  12. Solvation dynamics and rotational relaxation of coumarin 153 in mixed micelles of Triton X-100 and cationic gemini surfactants: effect of composition and spacer chain length of gemini surfactants.

    PubMed

    Sonu; Kumari, Sunita; Saha, Subit K

    2016-01-21

    Solvation dynamics and rotational relaxation of coumarin 153 (C-153) in mixed micelles of non-ionic surfactant, Triton X-100 and a series of cationic gemini surfactants, 12-s-12, 2Br with varying polymethylene spacer chain length (s = 3, 6, 8, 12) at different bulk mole fractions of a surfactant were studied. Studies were carried out by means of UV-Vis absorption, steady-state fluorescence and fluorescence anisotropy, time-resolved fluorescence and fluorescence anisotropy, and dynamic light scattering measurements. While micropolarity of the environment around C-153 in mixed micelles increased, the microviscosity decreased with increasing amount of a gemini surfactant. This is because the thickness of the Stern layer of micelles increases as a result of greater extent of penetration of water molecules. Solvation dynamics and rotational relaxation of C-153 become faster with increasing mole fraction of a gemini surfactant in the mixed micelles. Increasing the thickness of the Stern layer leads to an increase in the number of water molecules hydrogen bonded among themselves, resulting in an increase in polarity and microfluidity of the environment. At a given bulk mole fraction of a surfactant, the microviscosity of micelles decreases with increasing the spacer chain length of the gemini surfactant resulting in an increase in the rate of the rotational relaxation process. However, at a given bulk mole fraction of a surfactant, solvation dynamics becomes slower with increasing spacer chain length from s = 3 to 8 because of the increasing degree of counter ion dissociation. The slow rotational relaxation process is mainly due to the lateral diffusion of C-153 along the surface of the micelles. Rotationalmotion of the micelle as a whole is much slower than the lateral diffusion of C-153.

  13. The effect of the head-group spacer length of 12-s-12 gemini surfactants in the host-guest association with β-cyclodextrin.

    PubMed

    Carvalho, R A; Correia, H A; Valente, A J M; Söderman, O; Nilsson, M

    2011-02-15

    NMR spectroscopy has been used to study and characterize the interactions in solution between β-CD and alkyl-α,ω-bis(dodecyldimethyl ammonium bromide) gemini surfactants with the following head-group spacer lengths: 2, 4, 6, 8, and 10. The application of the method of continuous variation gives as a result that 1:1 and 2:1 (β-cyclodextrin-gemini) complexes are formed; the association stoichiometry is dependent on the spacer chain length, varying from 1.5 (for s=2) to 1.8 (for s=10). Assuming a two-step mechanism, the binding constants have been computed. In general, the overall binding constant slightly increases with an increase of the number of methylene groups in the spacer. The (1)H NMR spectra of the N-(CH(3))(2) groups in β-cyclodextrin/gemini mixed solutions are split into two peaks for 12-10-12, suggesting that the gemini spacer can thread the β-cyclodextrin so that the latter is positioned between the gemini head-groups. Inspection of the ROESY spectra allowed the establishment of several spatial proximities between the protons from the β-CD and the gemini and for a spacer length of 10, the data indeed indicate that complexes are formed with the CD molecule positioned between the two charged head groups with the spacer passing through the CD molecule.

  14. Structural studies of the formation of lipoplexes between siRNA and selected bis-imidazolium gemini surfactants.

    PubMed

    Andrzejewska, W; Pietralik, Z; Skupin, M; Kozak, M

    2016-10-01

    Dicationic (gemini) surfactants are agents that can be used for the preparation of stable complexes of nucleic acids, particularly siRNA for therapeutic purposes. In this study, we demonstrated that bis-imidazolium gemini surfactants with variable lengths of dioxyalkyl linker groups (from dioxyethyl to dioxydodecyl) and dodecyl side chains are excellent for the complexation of siRNA. All of these compounds effectively complexed siRNA in a charge ratio range (p/n) of 1.5-10. The low resolution structure of siRNA oligomers was characterised by small angle scattering of synchrotron radiation (SR-SAXS) and ab initio modelling. The structures of the formed complexes were also analysed using SR-SAXS, circular dichroism studies and electrophoretic mobility tests. The most promising agents for complexation with siRNA were the surfactants that contained dioxyethyl and dioxyhexyl spacer groups.

  15. Preparation of gemini-type amphiphiles bearing cyclitol head groups and their application as high-performance modifiers for lipases.

    PubMed

    Mine, Yurie; Fukunaga, Kimitoshi; Samejima, Ken-ichi; Yoshimoto, Makoto; Nakao, Katsumi; Sugimura, Yoshiaki

    2004-02-25

    Five gemini-type amphiphiles bearing cyclitol head groups, which have abundance of axial hydroxy groups, are newly synthesized. The syntheses are based on a common mixed anhydride method utilizing N,N'-[iminobis(trimethylene)]bisquinamide, prepared from iminobispropylamine and quino-1,5-lactone, and dialkyl N-(3-carboxypropanoyl)-L-glutamates as polar and hydrophobic components, respectively. Candida rugosa lipase (CRL) and Pseudomonas cepacia lipase (PCL) are co-lyophilized with these synthesized gemini-type amphiphiles, and their transesterification activities in organic solvents are evaluated. The modified PCL and CRL prepared by using each amphiphile showed highly enhanced and moderately enhanced enzyme activity, respectively. These results are discussed in terms of the increased preferential exclusion of the hydrophilic heads of the amphiphile and of the topological view of the amphiphile.

  16. Photoluminescence of CdSe/ZnS core-shell quantum dots stabilized in water with a pseudopeptidic gemini surfactant

    NASA Astrophysics Data System (ADS)

    Rubio, Jenifer; Izquierdo, M. Angeles; Burguete, M. Isabel; Galindo, Francisco; Luis, Santiago V.

    2011-09-01

    The use of pseudopeptidic gemini surfactants as stabilizers of hydrophobic quantum dots in water is discussed. Compound 1a acts as an intercalator with hydrophobic ligands of QDs transferring them from toluene to pure water yielding a fluorescent nanoparticle resistant to quenching by chloride anion (up to 0.1 M).The use of pseudopeptidic gemini surfactants as stabilizers of hydrophobic quantum dots in water is discussed. Compound 1a acts as an intercalator with hydrophobic ligands of QDs transferring them from toluene to pure water yielding a fluorescent nanoparticle resistant to quenching by chloride anion (up to 0.1 M). Electronic supplementary information (ESI) available: General experimental and synthetic procedures; NMR, ESI-MS spectra; FTIR, TEM and stability studies of water soluble QDs, fluorescent decay curves, effect of chloride, effect of concentration of 1a, and calculation of cmc. See DOI: 10.1039/c1nr10680e

  17. Processing requirements of secure C3/I and battle management systems - Development of Gemini trusted multiple microcomputer base

    NASA Astrophysics Data System (ADS)

    Tao, T. F.; Schell, R. R.

    The present investigation is concerned with the potential applications of trusted computer system technologies in space. It is suggested that the rapidly expanding roles of new space defense missions will require space-borne command, control, communication, intelligence, and battle management (C2/I-BM) systems. The trusted computer system technology can be extended to develop new computer architectures which are able to support the broader requirements of C3/I-BM processing. The Gemini Trusted Multiple Microcomputer Base product is being developed to meet the demanding requirements and to support simultaneously the multiple capabilities. Attention is given to recent important events of trusted computer system developments, and to the Gemini system architecture.

  18. EPICS and VxWorks for real-time motion control of the Altair adaptive optics instrument for Gemini

    NASA Astrophysics Data System (ADS)

    Ebbers, Angelic W.; Dunn, Jennifer

    2002-12-01

    The Instrument Group in the National Research Council of Canada's Herzberg Institute of Astrophysics develops instrumentation for large Astronomical telescopes including Altair (Gemini's ALTitude conjugate Adaptive optics for the InfraRed). This paper discusses how we responded to a need for adaptive intelligence and complex choreography and sequencing of mechanisms in the design of Altair's motion control systems. Our primary goal has been to maximize code reusability without sacrificing performance or flexibility.

  19. Characterization and monitoring of Flamingos-II, a near-IR imager and spectrograph at Gemini South

    NASA Astrophysics Data System (ADS)

    Krogsrud, David; Diaz, Ruben; Ferrero, Gabriel; Mora, Marcelo; Navarete, Felipe; Schirmer, Mischa

    2015-01-01

    We present results of the characterization and continual monitoring of the Flamingos-II instrument. Currently installed at Gemini South Observatory, Flamingos-II is a near-IR imager and longslit/multi-object spectrograph. In addition to the characterization of the detector, methodologies and results of the Science Verification pipeline, Telluric corrections, and Multi-Object Spectrograph (MOS) mask design software are presented.

  20. The Gemini Planet-finding Campaign: The Frequency Of Giant Planets around Debris Disk Stars

    NASA Astrophysics Data System (ADS)

    Wahhaj, Zahed; Liu, Michael C.; Nielsen, Eric L.; Biller, Beth A.; Hayward, Thomas L.; Close, Laird M.; Males, Jared R.; Skemer, Andrew; Ftaclas, Christ; Chun, Mark; Thatte, Niranjan; Tecza, Matthias; Shkolnik, Evgenya L.; Kuchner, Marc; Reid, I. Neill; de Gouveia Dal Pino, Elisabete M.; Alencar, Silvia H. P.; Gregorio-Hetem, Jane; Boss, Alan; Lin, Douglas N. C.; Toomey, Douglas W.

    2013-08-01

    We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.''5 and 14.1 mag at 1'' separation. Follow-up observations of the 66 candidates with projected separation <500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known β Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a >=5 M Jup planet beyond 80 AU, and <21% of debris disk stars have a >=3 M Jup planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly imaged planets as d 2 N/dMdavpropm α a β, where m is planet mass and a is orbital semi-major axis (with a maximum value of a max). We find that β < -0.8 and/or α > 1.7. Likewise, we find that β < -0.8 and/or a max < 200 AU. For the case where the planet frequency rises sharply with mass (α > 1.7), this occurs because all the planets detected to date have masses above 5 M Jup, but planets of lower mass could easily have been detected by our search. If we ignore the β Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that <20% of debris disk stars have a >=3 M Jup planet beyond 10 AU, and β < -0.8 and/or α < -1.5. Likewise, β < -0.8 and/or a max < 125 AU. Our Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet

  1. Enhanced aqueous solubility of polycyclic aromatic hydrocarbons by green diester-linked cationic gemini surfactants and their binary solutions

    NASA Astrophysics Data System (ADS)

    Panda, Manorama; Fatma, Nazish; Kabir-ud-Din

    2016-07-01

    Three homologues of a novel biodegradable diester-linked cationic gemini surfactant series, CmH2m+1 (CH3)2N+(CH2COOCH2)2N+(CH3)2CmH2m+1.2Cl- (m-E2-m; m = 12, 14, 16), were used for investigation of the solubilization of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, anthracene and pyrene in single as well as binary surfactant solutions. Physicochemical parameters of the pure/mixed systems were derived by conductivity and surface tension measurements. Dissolution capacity of the equimolar binary surfactant solutions towards the PAHs was studied from the molar solubilization ratio (MSR), micelle-water partition coefficient (Km) and free energy of solubilization (ΔGs0) of the solubilizates. Influence of hydrophobic chain length of the dimeric surfactants on solubilization was characterized. Aqueous solubility of the PAHs was enhanced linearly with concentration of the surfactant in all the pure and mixed gemini-gemini surfactant systems.

  2. Effect of gemini surfactant (16-6-16) on the synthesis of silver nanoparticles: A facile approach for antibacterial application.

    PubMed

    Siddiq, A Mohammed; Parandhaman, Thanusu; Begam, A Farzana; Das, Sujoy K; Alam, Md Sayem

    2016-12-01

    In this report, we describe the effect of Gemini surfactants1, 6-Bis (N, N-hexadecyldimethylammonium) adipate (16-6-16) on synthesis, stability and antibacterial activity of silver nanoparticles (AgNPs). The stabilizing effect of Gemini surfactant and aggregation behavior of AgNPs was evaluated by plasmonic property and morphology of the AgNPs were characterized by UV-vis spectroscopy, Dynamic Light Scattering (DLS), X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM) and Energy dispersive X-ray analysis (EDX) techniques. Interestingly, the formation of quite mono-dispersed spherical particles was found. Apart from the stabilizing role, the Gemini surfactant has promoted the agglomeration of individual AgNPs in small assemblies whose Plasmon band features differed from those of the individual nanoparticles. The antibacterial activity of the synthesized AgNPs on Gram-negative and Gram-positive bacterium viz., E. coli and S. aureus was carried out by plate count, growth kinetics and cell viability assay. Furthermore, the mechanism of antibacterial activity of AgNPs was tested by Zeta potential and DLS analysis, to conclude that surface charge of AgNPs disrupts the cells causing cell death.

  3. Near-Infrared Observations of GQ Lup b Using the Gemini Integral Field Spectrograph NIFS

    NASA Astrophysics Data System (ADS)

    Lavigne, Jean-François; Doyon, René; Lafrenière, David; Marois, Christian; Barman, Travis

    2009-10-01

    We present new JHK spectroscopy (R ~ 5000) of GQ Lup b, acquired with the Near-Infrared Integral Field Spectrograph and the adaptive optics system ALTAIR at the Gemini North telescope. Angular differential imaging was used in the J and H bands to suppress the speckle noise from GQ Lup A; we show that this approach can provide improvements in signal-to-noise ratio (S/N) by a factor of 2-6 for companions located at subarcsecond separations. Based on high-quality observations and Global Astrometric lnterferometer for Astrophysics synthetic spectra, we estimate the companion effective temperature to T eff = 2400 ± 100 K, its gravity to log g = 4.0 ± 0.5, and its luminosity to log(L/L sun) = -2.47 ± 0.28. Comparisons with the predictions of the DUSTY evolutionary tracks allow us to constrain the mass of GQ Lup b to 8-60 M Jup, most likely in the brown dwarf regime. Compared with the spectra published by Seifahrt and collaborators, our spectra of GQ Lup b are significantly redder (by 15%-50%) and do not show important Paβ emission. Our spectra are in excellent agreement with the lower S/N spectra previously published by McElwain and collaborators.

  4. OCTOCAM: a fast multi-channel imager and spectrograph proposed for the Gemini Observatory

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, A.; Roming, P.; Thöne, C. C.; van der Horst, A. J.; Pope, S.; García Vargas, M. L.; Sánchez-Blanco, E.; Maldonado Medina, M.; Content, R.; Snik, F.; Killough, R.; Winters, G.; Persson, K.; Jeffers, S.; Riva, A.; Bianco, A.; Zanutta, A.

    2016-08-01

    OCTOCAM has been proposed to the Gemini Observatory as a workhorse imager and spectrograph that will fulfill the needs of a large number of research areas in the 2020s. It is based on the use of high-efficiency dichroics to divide the incoming light in eight different channels, four optical and four infrared, each optimized for its wavelength range. In its imaging mode, it will observe a field of 3'x3' simultaneously in g, r, i, z, Y, J, H, and KS bands. It will obtain long-slit spectroscopy covering the range from 3700 to 23500 Å with a resolution of 4000 and a slit length of 3 arcminutes. To avoid slit losses, the instrument it will be equipped with an atmospheric dispersion corrector for the complete spectral range. Thanks to the use of state of the art detectors, OCTOCAM will allow high time-resolution observations and will have negligible overheads in classical observing modes. It will be equipped with a unique integral field unit that will observe in the complete spectral range with an on-sky coverage of 9.7"x6.8", composed of 17 slitlets, 0.4" wide each. Finally, a state-of-the-art polarimetric unit will allow us to obtain simultaneous full Stokes spectropolarimetry of the range between 3700 and 22000 Å.

  5. RADIO GALAXY 3C 230 OBSERVED WITH GEMINI LASER ADAPTIVE-OPTICS INTEGRAL-FIELD SPECTROSCOPY

    SciTech Connect

    Steinbring, Eric

    2011-11-15

    The Altair laser-guide-star adaptive optics facility combined with the near-infrared integral-field spectrometer on Gemini North have been employed to study the morphology and kinematics of 3C 230 at z = 1.5, the first such observations of a high-redshift radio galaxy. These suggest a bi-polar outflow spanning 0.''9 ({approx}16 kpc projected distance for a standard {Lambda} CDM cosmology) reaching a mean relative velocity of 235 km s{sup -1} in redshifted H{alpha} +[N II] and [S II] emission. Structure is resolved to 0.''1 (0.8 kpc), which is well correlated with optical images from the Hubble Space Telescope and Very Large Array radio maps obtained at similar spatial resolution. Line diagnostics suggest that over the 10{sup 7} yr to 10{sup 8} yr duration of its active galactic nucleus activity, gas has been ejected into bright turbulent lobes at rates comparable to star formation, although constituting perhaps only 1% of the baryonic mass in the galaxy.

  6. GEMINI MULTI-OBJECT SPECTROGRAPH SPECTROSCOPY OF EXO 0748-676 (=UY Vol) IN OUTBURST

    SciTech Connect

    Mikles, Valerie J.; Hynes, Robert I. E-mail: rih@phys.lsu.edu

    2012-05-10

    We present a phase-resolved, optical, spectroscopic study of the eclipsing low-mass X-ray binary, EXO 0748-676 = UY Vol. The sensitivity of Gemini, combined with our complete phase coverage, makes for the most detailed blue spectroscopic study of this source obtained during its extended 24 year period of activity. We identify 12 optical emission lines and present trailed spectra, tomograms, and the first modulation maps of this source in outburst. The strongest line emission originates downstream of the stream-impact point, and this component is quite variable from night to night. Underlying this is weaker, more stable axisymmetric emission from the accretion disk. We identify weak, sharp emission components moving in phase with the donor star, from which we measure K{sub em} = 329 {+-} 26 km s{sup -1}. Combining all the available dynamical constraints on the motion of the donor star with our observed accretion disk velocities, we favor a neutron star mass close to canonical (M{sub 1} {approx_equal} 1.5 M{sub Sun }) and a very low mass donor (M{sub 2} {approx_equal} 0.1 M{sub Sun }). We note, however, that there is no evidence for CNO processing, which is often associated with undermassive donor stars. A main-sequence donor would require both a neutron star more massive than 2 M{sub Sun }, and substantially sub-Keplerian disk emission.

  7. The Gemini-Monoceros X-ray enhancement - A giant X-ray ring

    NASA Technical Reports Server (NTRS)

    Nousek, J. A.; Lindblad, C. J.; Garmire, G. P.; Cowie, L. L.; Hu, E.

    1981-01-01

    A 1.5 deg spatial resolution map of the 1/4 KeV diffuse X-ray background enhancement in the Gemini and Monoceros constellations is found to show a circular ring-shaped emission feature with a diameter of 20 deg. The feature and possible X-ray contributions from the Mon OB1 association and neighboring supernova remnants are discussed. From 300 pc, the region has a radius of 50 pc, with an emitting electron density of 0.01 per cu cm. A shell of expanding neutral hydrogen and nonthermal radio spur is observed outside the ring with the X-ray emitting pulsar PSR 0656 + 14 lying close to the center of the ring. Origins of the ring are discussed, ruling out formation by the association Mon OB1. The ring is considered to be a field supernova remnant formed by the progenitor of the central pulsar, and providing constraints on theories of remnant evolution. This conclusion is found to agree with estimated supernova rates, and the absence of additional examples of this stage of evolution is an observational selection effect.

  8. A Deuteration Survey of the Clump Population in the Gemini OB1 Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Henrici, Andrew Scott; Shirley, Yancy L.; Svoboda, Brian E.

    2017-01-01

    Recent maps of dust continuum emission from entire molecular clouds at submillimeter wavelengths have made it possible to survey and study the chemistry of entire core and clump populations within a single cloud. One very strong chemical process in star-forming regions is the fractionation of deuterium in molecules, which results in an increase in the deuterium ratio many orders of magnitude over the ISM [D]/[H] ratio and provides a chemical probe of cold, dense regions. We present a survey of DCO+ 3-2 and N2D+ 3-2 toward the clump population in the high-mass, star-forming Gemini OB1 Molecular Cloud identified from 1.1 mm continuum imaging by the Bolocam Galactic Plane Survey. The peak 1.1 mm continuum positions of 52 clumps in the range 188°≤ l ≤194° were observed with the 10m Heinrich Hertz Submillimeter Telescope. We find that DCO+ emission is detected toward 90% of the clumps with a median deuterium ratio of 0.01 while N2D+ emission is detected toward only 25% of the clumps. The DCO+ fractionation anti-correlates with gas kinetic temperature and linewidth, a measure of the amount of turbulence within the clumps. We compare the deuteration ratios of with physical properties of the clumps and their evolutionary stage.

  9. Adaptive optics imaging of QSO host galaxies with Hokupa'a on the Gemini North telescope

    NASA Astrophysics Data System (ADS)

    Guyon, O.; Sanders, D. B.; Stockton, A.; Baudoz, P.; Potter, D.

    2001-05-01

    We report the initial results of a new near-infrared imaging survey of quasar hosts using the University of Hawaii Hokupa'a Adaptive Optics system on the 8.2m Gemini-North telescope. J,H,K' images of a complete subsample ( 25) of nearby (z <0.3), "bona-fide" optically selected (MB < -23; Ho = 50, qo=0; Schmidt & Green 1983) QSOs are being taken in order to obtain accurate host galaxy magnitudes and colors and to determine two-dimensional structure. In the initial phase of our observations we found that PSF subtraction residuals were severely limiting our ability to characterize the host galaxy. However we were able to obtain a significant increase in stability of the PSF by turning off the Cassegrain rotator during observations (see Roth et al. contribution at this meeting). Our sample of Palomar-Green Bright QSOs includes both radio quiet and radio loud objects plus objects spanning the full range of observed "infrared excess" continuum emission. One of the most surprising results has been the detection of modest scale (3-5" 5 kpc diameter) "bars" and/or circumnuclear "disks" that were not evident in previous one-dimensional profile analyses. These structures may be related to the reservoir of fuel needed to power the QSO and may provide important clues concerning the origin and evolution of QSO hosts.

  10. Adaptive optics for direct detection of extrasolar planets: the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce; Graham, James; Palmer, David; Doyon, Rene; Gavel, Don; Larkin, James; Oppenheimer, Ben; Saddlemyer, Leslie; Wallace, J. Kent; Bauman, Brian; Erikson, Darren; Poyneer, Lisa; Sivaramakrishnan, Anand; Soummer, Rémi; Veran, Jean-Pierre

    2007-04-01

    The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5 50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new, dedicated, high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI). This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10-7 of their parent star, sufficient to observe warm self-luminous planets around a large population of targets. To cite this article: B. Macintosh et al., C. R. Physique 8 (2007).

  11. A Gemini Planet Imager investigation of the atmosphere of the HD 95086b planet

    NASA Astrophysics Data System (ADS)

    De Rosa, Robert J.; Pueyo, Laurent; Patience, Jenny; Graham, James R.; Gemini Planet Imager Team

    2015-01-01

    We present Gemini Planet Imager (GPI) near-infrared observations of the ~5 Mjup companion to the young, dusty A-type star HD 95086, observed during the course of the verification and commissioning of the instrument. By combining binned low-resolution H and K-band IFS spectra from GPI, with literature near and mid-IR photometry, we have undertaken the most comprehensive analysis of the spectral energy distribution of HD 95086 b to-date. Comparing these observational results with atmospheric models, we constrain key parameters such as the effective temperature and surface gravity, and place the results in the context of analyses of other directly imaged planetary-mass companions (e.g. HR 8799 bcde, β Pic b), and other substellar companions at a similar age (e.g. HD 106906 b, GQ Lup b). We also comment on the sensitivity of companions interior and exterior to HD 95086 b. Lastly, we present the color-corrections derived during the course of this study that are required to transform photometry obtained with GPI in the K1 and K2 filters into both the MKO and 2MASS photometric systems, essential for the propoer interpretation of K-band photometry measurements obtained with GPI.

  12. Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts.

    PubMed

    Grirrane, Abdessamad; Álvarez, Eleuterio; García, Hermenegildo; Corma, Avelino

    2017-02-24

    Tremorine and precursors of gemini surfactants were synthesised in a one-pot, three-step, double-catalytic A(3) coupling reaction and characterised by structural and spectroscopic methods. The cationic [Au(I) (L1)]SbF6 complex is a more active catalyst compared to neutral L2- and L3-Au(I) bis(trifluoromethanesulfonyl)imidate complexes (L1, L2=Buchwald-type biaryl phosphane; L3=triphenylphosphine) in promoting the double A(3) coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide-bridged cationic digold(I) L1 and L2 complexes were isolated and characterised by means of single-crystal X-ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the Au(I) catalyst by formation of the less active iodido-bridged cationic digold(I) L1 complex, which was fully characterised by single-crystal X-ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl-bridged Au(I)2 -L intermediates, isolation of which lends support to the proposed double A(3) coupling mechanism.

  13. Determination of nanograms of proteins based on decreased resonance light scattering of zwitterionic gemini surfactant.

    PubMed

    Chen, Zhanguang; Liu, Guoliang; Chen, Maohuai; Peng, Yurui; Wu, Mingyao

    2009-01-15

    A new high-sensitivity detection of protein assay at the nanogram level is proposed based on the decreased resonance light scattering (RLS) signals of zwitterionic gemini surfactant (phosphodiesters quaternary ammonium salt [PQAS]). It was found that PQAS self-assembled into nanometer-scale PQAS aggregates, which induced intense RLS signal in Britton-Robinson (BR) buffer solution (pH 10.5). Under the optimum conditions, the RLS intensity quenching extent of PQAS aggregation was in proportion to the concentration of proteins in the range of 0.0012-1.08 microg/ml for bovine serum albumin, 0.0015-0.95 microg/ml for human serum albumin, and 0.0025-1.3 microg/ml for gamma-globulin. The detection limits were 0.8, 1.2, and 2.0 ng/ml, respectively. The proposed method was successfully applied to determine total protein in human serum samples, and the results were identical to those obtained by the Bradford assay. The mechanism of interaction between PQAS and protein was studied using RLS, fluorescence, and time-resolved fluorescence, which indicated that the new complex formed between them, disaggregating self-aggregation of PQAS, resulted in the dominated quenching of RLS signal of the assay system.

  14. Remote loading of aloe emodin in gemini-based cationic liposomes.

    PubMed

    Giuliani, Chiara; Altieri, Barbara; Bombelli, Cecilia; Galantini, Luciano; Mancini, Giovanna; Stringaro, Annarita

    2015-01-01

    Anthraquinone compound aloe-emodin (AE) has shown antineoplastic, antibacterial, antiviral, and anti-inflammatory properties and scavenging activity on free radicals. Because of these therapeutic features, AE has been attracting increasing interest and could be applied in the curing of many diseases. However, until now the physicochemical features of this compound have not been fully investigated; furthermore, its wide application might be hindered by its scarce solubility in aqueous media (∼19 μM). The inclusion of AE in nanocarriers, such as cationic liposomes, could allow its delivery effectively and selectively to target sites, reducing side effects in the remaining tissues. In this work, the weak acid nature of AE, because of its two phenolic functions, was exploited to load it remotely in the internal aqueous phase of liposomes in response to a difference in pH between the inside and outside of the liposomes, pHin > pHout. The inclusion of AE in gemini-based cationic liposomes by the acetate gradient method was obtained at high AE/lipid ratios (up to 1:30).

  15. Gemini Planet Imager observational calibrations XI: pipeline improvements and enhanced calibrations after two years on sky

    NASA Astrophysics Data System (ADS)

    Perrin, Marshall D.; Ingraham, Patrick; Follette, Katherine B.; Maire, Jérôme; Wang, Jason J.; Savransky, Dmitry; Arriaga, Pauline; Bailey, Vanessa P.; Bruzzone, Sebastian; Chilcote, Jeffrey K.; De Rosa, Robert J.; Draper, Zachary H.; Fitzgerald, Michael P.; Greenbaum, Alexandra Z.; Hung, Li-Wei; Konopacky, Quinn; Macintosh, Bruce; Marchis, Franck; Marois, Christian; Millar-Blanchaer, Maxwell A.; Nielsen, Eric; Rajan, Abhijith; Rameau, Julien; Rantakyro, Fredrik T.; Ruffio, Jean-Baptiste; Ward-Duong, Kimberly; Wolff, Schuyler G.; Zalesky, Joseph

    2016-08-01

    The Gemini Planet Imager has been successfully obtaining images and spectra of exoplanets, brown dwarfs, and debris and protoplanetary circumstellar disks using its integral field spectrograph and polarimeter. GPI observations are transformed from raw data into high-quality astrometrically and photometrically calibrated datacubes using the GPI Data Reduction Pipeline, an open-source software framework continuously developed by our team and available to the community. It uses a flexible system of reduction recipes composed of individual primitive steps, allowing substantial customization of processing depending upon science goals. This paper provides a broad overview of the GPI pipeline, summarizes key lessons learned, and describes improved calibration methods and new capabilities available in the latest version. Enhanced automation better supports observations at the telescope with streamlined and rapid data processing, for instance through real-time assessments of contrast performance and more automated calibration file processing. We have also incorporated the GPI Data Reduction Pipeline as one component in a larger automated data system to support the GPI Exoplanet Survey campaign, while retaining its flexibility and stand-alone capabilities to support the broader GPI observer community. Several accompanying papers describe in more detail specific aspects of the calibration of GPI data in both spectral and polarimetric modes.

  16. Crystalline structures and mesomorphic properties of gemini diammonium surfactants with a pendant hydroxyl group.

    PubMed

    Wei, Zengbin; Wei, Xilian; Sun, Dezhi; Liu, Jiuqiang; Tang, Xiaojuan

    2011-02-15

    A series of homologous crystals of gemini diammonium surfactants (GDAS) containing one hydroxyl substituted methylene spacer are prepared. The crystal structures of these compounds, namely [C(n)H(2)(n)(+1)-N(+) (CH(3))(2)-CH(2)CH(OH)CH(2)-N(+)(CH(3))(2)-C(n)H(2)(n)(+1)], are determined by single-crystal X-ray diffraction techniques, in order to have a better understanding of the structure relation between the solid and the mesophase. The hydroxyl groups enhance the hydrogen bonding interaction between neighboring compounds, and therefore the packing of GDAS in the solid state is arranged to form a herringbone-like mode. To the best of our knowledge, this is the first GDAS crystal with a herringbone-like structure. Their mesomorphic properties are investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray powder diffraction, and rheological measurement. These compounds have relatively low melting points and form thermotropic mesophases over a broad temperature range, as compared to those without a hydroxyl substituted at the spacer. The rheological behavior of the smectic phases clearly reveals that hydrogen bonds exert a significant effect on the high values of moduli and viscosity. Moreover, the melting point and rheological parameters increase, conforming to the length of alkyl chains.

  17. Adaptive Optics for Direct Detection of Extrasolar Planets: The Gemini Planet Imager

    SciTech Connect

    Macintosh, B; Graham, J; Palmer, D; Doyon, R; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Wallace, J K; Bauman, B; Erikson, D; Poyneer, L; Sivaramakrishnan, A; Soummer, R; Veran, J

    2007-04-24

    The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5-50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new dedicated high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI.) This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10{sup -7} of their parent star, sufficient to observe warm self-luminous planets around a large population of targets.

  18. Nonviral gene-delivery by highly fluorinated gemini bispyridinium surfactant-based DNA nanoparticles.

    PubMed

    Fisicaro, Emilia; Compari, Carlotta; Bacciottini, Franco; Contardi, Laura; Pongiluppi, Erika; Barbero, Nadia; Viscardi, Guido; Quagliotto, Pierluigi; Donofrio, Gaetano; Krafft, Marie Pierre

    2017-02-01

    Biological and thermodynamic properties of a new homologous series of highly fluorinated bispyridinium cationic gemini surfactants, differing in the length of the spacer bridging the pyridinium polar heads in 1,1' position, are reported for the first time. Interestingly, gene delivery ability is closely associated with the spacer length due to a structural change of the molecule in solution. This conformation change is allowed when the spacer reaches the right length, and it is suggested by the trends of the apparent and partial molar enthalpies vs molality. To assess the compounds' biological activity, they were tested with an agarose gel electrophoresis mobility shift assay (EMSA), MTT proliferation assay and Transient Transfection assays on a human rhabdomyosarcoma cell line. Data from atomic force microscopy (AFM) allow for morphological characterization of DNA nanoparticles. Dilution enthalpies, measured at 298K, enabled the determination of apparent and partial molar enthalpies vs molality. All tested compounds (except that with the longest spacer), at different levels, can deliver the plasmid when co-formulated with 1,2-dioleyl-sn-glycero-3-phosphoethanolamine (DOPE). The compound with a spacer formed by eight carbon atoms gives rise to a gene delivery ability that is comparable to that of the commercial reagent. The compound with the longest spacer compacts DNA in loosely condensed structures by forming bows, which are not suitable for transfection. Regarding the compounds' hydrogenated counterparts, the tight relationship between the solution thermodynamics data and their biological performance is amazing, making "old" methods the foundation to deeply understanding "new" applications.

  19. Evaluation of β-cyclodextrin-modified gemini surfactant-based delivery systems in melanoma models

    PubMed Central

    Michel, Deborah; Mohammed-Saeid, Waleed; Getson, Heather; Roy, Caitlin; Poorghorban, Masoomeh; Chitanda, Jackson M; Verrall, Ronald; Badea, Ildiko

    2016-01-01

    Novel drug delivery systems are developed to improve the biological behavior of poorly soluble drugs and to improve therapeutic outcomes. In melanoma therapy, the goal is efficient drug delivery and mitigation of drug resistance. Melphalan (Mel), a currently used therapeutic agent for melanoma, requires solvent system for solubilization, leading to poor chemical stability. Moreover, drug resistance often renders the drug inefficient in clinical setting. A novel β-cyclodextrin-modified gemini surfactant (CDgemini) delivery system was developed to incorporate Mel in order to improve its physicochemical and biological behavior. Melphalan nanoparticles (Mel-NP) showed optimal particle size in the 200–250 nm range for endocytosis and induced significantly higher cell death compared with Mel (50% of inhibitory concentration [IC50] of 36 µM for the complexes vs 82 µM for Mel). The CDgemini delivery system did not alter the pathway of the cellular death triggered by Mel and caused no intrinsic toxicity to the cells. The Mel-NP complexes induced significant cell death in melanoma cells that were rendered resistant to Mel. These findings demonstrate in principle the applicability of the CDgemini delivery system as safe and efficient alternative to the current melanoma therapy, especially in chemoresistant cases. PMID:28003746

  20. GEMINI: Initial behavioral results after full severance of the cervical spinal cord in mice

    PubMed Central

    Kim, C-Yoon; Oh, Hanseul; Hwang, In-Kyu; Hong, Ki-Sung

    2016-01-01

    Background: The GEMINI spinal cord fusion protocol has been developed to achieve a successful cephalosomatic anastomosis. Here, we report the preliminary data on the use of a fusogen [polyethylene glycol (PEG)] after full cervical cord transection in mice to facilitate the fusion of both ends of a sharply transected spinal cord. Methods: Cervical laminectomy and a complete, visually confirmed cervical cord (C 5) transection was performed on female albino mice (n = 16). In Group 1 (n = 8), a fusogen, (PEG) was used to bridge the gap between the cut ends of the spinal cord. Group 2 received the same spinal cord transection but was treated with saline. Outcome was assessed daily using a standard scale (modified 22-point Basso-Beattie-Bresnahan scale) and filmed on camera. Results: The PEG group (group 1) showed partial restoration of motor function after 4 weeks of observation; group 2 (placebo) did not recover any useful motor activity. Conclusion: In this preliminary experiment, PEG, but not saline, promoted partial motor recovery in mice submitted to full cervical transection. PMID:27656325

  1. NEAR-INFRARED OBSERVATIONS OF GQ LUP b USING THE GEMINI INTEGRAL FIELD SPECTROGRAPH NIFS

    SciTech Connect

    Lavigne, Jean-Francois; Doyon, Rene; Lafreniere, David; Marois, Christian; Barman, Travis

    2009-10-20

    We present new JHK spectroscopy (R approx 5000) of GQ Lup b, acquired with the Near-Infrared Integral Field Spectrograph and the adaptive optics system ALTAIR at the Gemini North telescope. Angular differential imaging was used in the J and H bands to suppress the speckle noise from GQ Lup A; we show that this approach can provide improvements in signal-to-noise ratio (S/N) by a factor of 2-6 for companions located at subarcsecond separations. Based on high-quality observations and Global Astrometric lnterferometer for Astrophysics synthetic spectra, we estimate the companion effective temperature to T {sub eff} = 2400 +- 100 K, its gravity to log g = 4.0 +- 0.5, and its luminosity to log(L/L {sub sun}) = -2.47 +- 0.28. Comparisons with the predictions of the DUSTY evolutionary tracks allow us to constrain the mass of GQ Lup b to 8-60 M {sub Jup}, most likely in the brown dwarf regime. Compared with the spectra published by Seifahrt and collaborators, our spectra of GQ Lup b are significantly redder (by 15%-50%) and do not show important Pabeta emission. Our spectra are in excellent agreement with the lower S/N spectra previously published by McElwain and collaborators.

  2. THE PDS 66 CIRCUMSTELLAR DISK AS SEEN IN POLARIZED LIGHT WITH THE GEMINI PLANET IMAGER

    SciTech Connect

    Wolff, Schuyler G.; Greenbaum, Alexandra Z.; Perrin, Marshall; Hines, Dean C.; Millar-Blanchaer, Maxwell A.; Nielsen, Eric L.; Wang, Jason; Dong, Ruobing; Duchêne, Gaspard; Graham, James R.; Kalas, Paul; Cardwell, Andrew; Chilcote, Jeffrey; Draper, Zachary H.; Fitzgerald, Michael P.; Hung, Li-Wei; Goodsell, Stephen J.; Grady, Carol A.; Hartung, Markus; Hibon, Pascale; and others

    2016-02-10

    We present H- and K-band imaging polarimetry for the PDS 66 circumstellar disk obtained during the commissioning of the Gemini Planet Imager (GPI). Polarization images reveal a clear detection of the disk in to the 0.″12 inner working angle (IWA) in the H band, almost three times closer to the star than the previous Hubble Space Telescope (HST) observations with NICMOS and STIS (0.″35 effective IWA). The centro-symmetric polarization vectors confirm that the bright inner disk detection is due to circumstellar scattered light. A more diffuse disk extends to a bright outer ring centered at 80 AU. We discuss several physical mechanisms capable of producing the observed ring + gap structure. GPI data confirm enhanced scattering on the east side of the disk that is inferred to be nearer to us. We also detect a lateral asymmetry in the south possibly due to shadowing from material within the IWA. This likely corresponds to a temporally variable azimuthal asymmetry observed in HST/STIS coronagraphic imaging.

  3. The lick-index calibration of the Gemini multi-object spectrographs

    SciTech Connect

    Puzia, Thomas H.; Miller, Bryan W.; Trancho, Gelys; Basarab, Brett; Mirocha, Jordan T.; Butler, Karen E-mail: bmiller@gemini.edu

    2013-06-01

    We present the calibration of the spectroscopic Lick/IDS standard line-index system for measurements obtained with the Gemini Multi-Object Spectrographs known as GMOS-North and GMOS-South. We provide linear correction functions for each of the 25 standard Lick line indices for the B600 grism and two instrumental setups, one with 0.''5 slit width and 1 × 1 CCD pixel binning (corresponding to ∼2.5 Å spectral resolution) and the other with 0.''75 slit width and 2 × 2 binning (∼4 Å). We find small and well-defined correction terms for the set of Balmer indices Hβ, Hγ {sub A}, and Hδ {sub A} along with the metallicity sensitive indices Fe5015, Fe5270, Fe5335, Fe5406, Mg{sub 2}, and Mgb that are widely used for stellar population diagnostics of distant stellar systems. We find other indices that sample molecular absorption bands, such as TiO{sub 1} and TiO{sub 2}, with very wide wavelength coverage or indices that sample very weak molecular and atomic absorption features, such as Mg{sub 1}, as well as indices with particularly narrow passband definitions, such as Fe4384, Ca4455, Fe4531, Ca4227, and Fe5782, which are less robustly calibrated. These indices should be used with caution.

  4. Dynamics of Water in Gemini Surfactant-Based Lyotropic Liquid Crystals

    DOE PAGES

    McDaniel, Jesse G.; Mantha, Sriteja; Yethiraj, Arun

    2016-09-26

    The dynamics of water confined to nanometer-sized domains is important in a variety of applications ranging from proton exchange membranes to crowding effects in biophysics. In this work we study the dynamics of water in gemini surfactant-based lyotropic liquid crystals (LLCs) using molecular dynamics simulations. These systems have well characterized morphologies, e.g., hexagonal, gyroid, and lamellar, and the surfaces of the confining regions can be controlled by modifying the headgroup of the surfactants. This allows one to study the effect of topology, functionalization, and interfacial curvature on the dynamics of confined water. Through analysis of the translational diffusion and rotationalmore » relaxation we conclude that the hydration level and resulting confinement lengthscale is the predominate determiner of the rates of water dynamics, and other effects, namely surface functionality and curvature, are largely secondary. In conclusion, this novel analysis of the water dynamics in these LLC systems provides an important comparison for previous studies of water dynamics in lipid bilayers and reverse micelles.« less

  5. Water Dynamics in Gyroid Phases of Self-Assembled Gemini Surfactants

    SciTech Connect

    Roy, Santanu; Skoff, David; Perroni, Dominic V.; Mondal, Jagannath; Yethiraj, Arun; Mahanthappa, Mahesh K.; Zanni, Martin T.; Skinner, James L.

    2016-02-14

    Water-mediated ion transport through functional nanoporous materials depends on the dynamics of water confined within a given nanostructured morphology. In this study, we investigate hydrogen-bonding dynamics of interfacial water within a ‘normal’ (Type I) lyotropic gyroid phase formed by a gemini dicarboxylate surfactant self-assembly using a combina- tion of 2DIR spectroscopy and molecular dynamics simulations. Experiments and simulations demonstrate that water dynamics in the normal gyroid phase is one order of magnitude slower than that in bulk water, due to specific interactions between water, the ionic surfactant headgroups, and counterions. However, the dynamics of water in the normal gyroid phase are faster than those of water confined in a reverse spherical micelle of a sulfonate surfactant, given that the water pool in the reverse micelle and the water pore in the gyroid phase have roughly the same diameters. This difference in confined water dynamics likely arises from the significantly reduced curvature- induced frustration at the convex interfaces of the normal gyroid, as compared to the concave interfaces of a reverse spherical micelle. These detailed insights into confined water dynamics may guide the future design of artificial membranes that rapidly transport protons and other ions.

  6. Dynamics of Water in Gemini Surfactant-Based Lyotropic Liquid Crystals

    SciTech Connect

    McDaniel, Jesse G.; Mantha, Sriteja; Yethiraj, Arun

    2016-09-26

    The dynamics of water confined to nanometer-sized domains is important in a variety of applications ranging from proton exchange membranes to crowding effects in biophysics. In this work we study the dynamics of water in gemini surfactant-based lyotropic liquid crystals (LLCs) using molecular dynamics simulations. These systems have well characterized morphologies, e.g., hexagonal, gyroid, and lamellar, and the surfaces of the confining regions can be controlled by modifying the headgroup of the surfactants. This allows one to study the effect of topology, functionalization, and interfacial curvature on the dynamics of confined water. Through analysis of the translational diffusion and rotational relaxation we conclude that the hydration level and resulting confinement lengthscale is the predominate determiner of the rates of water dynamics, and other effects, namely surface functionality and curvature, are largely secondary. In conclusion, this novel analysis of the water dynamics in these LLC systems provides an important comparison for previous studies of water dynamics in lipid bilayers and reverse micelles.

  7. Water Dynamics in Gyroid Phases of Self-Assembled Gemini Surfactants

    DOE PAGES

    Roy, Santanu; Skoff, David; Perroni, Dominic V.; ...

    2016-02-14

    Water-mediated ion transport through functional nanoporous materials depends on the dynamics of water confined within a given nanostructured morphology. In this study, we investigate hydrogen-bonding dynamics of interfacial water within a ‘normal’ (Type I) lyotropic gyroid phase formed by a gemini dicarboxylate surfactant self-assembly using a combina- tion of 2DIR spectroscopy and molecular dynamics simulations. Experiments and simulations demonstrate that water dynamics in the normal gyroid phase is one order of magnitude slower than that in bulk water, due to specific interactions between water, the ionic surfactant headgroups, and counterions. However, the dynamics of water in the normal gyroid phasemore » are faster than those of water confined in a reverse spherical micelle of a sulfonate surfactant, given that the water pool in the reverse micelle and the water pore in the gyroid phase have roughly the same diameters. This difference in confined water dynamics likely arises from the significantly reduced curvature- induced frustration at the convex interfaces of the normal gyroid, as compared to the concave interfaces of a reverse spherical micelle. These detailed insights into confined water dynamics may guide the future design of artificial membranes that rapidly transport protons and other ions.« less

  8. Hydrophilic interaction liquid chromatography-tandem mass spectrometry quantitative method for the cellular analysis of varying structures of gemini surfactants designed as nanomaterial drug carriers.

    PubMed

    Donkuru, McDonald; Michel, Deborah; Awad, Hanan; Katselis, George; El-Aneed, Anas

    2016-05-13

    Diquaternary gemini surfactants have successfully been used to form lipid-based nanoparticles that are able to compact, protect, and deliver genetic materials into cells. However, what happens to the gemini surfactants after they have released their therapeutic cargo is unknown. Such knowledge is critical to assess the quality, safety, and efficacy of gemini surfactant nanoparticles. We have developed a simple and rapid liquid chromatography electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the quantitative determination of various structures of gemini surfactants in cells. Hydrophilic interaction liquid chromatography (HILIC) was employed allowing for a short simple isocratic run of only 4min. The lower limit of detection (LLOD) was 3ng/mL. The method was valid to 18 structures of gemini surfactants belonging to two different structural families. A full method validation was performed for two lead compounds according to USFDA guidelines. The HILIC-MS/MS method was compatible with the physicochemical properties of gemini surfactants that bear a permanent positive charge with both hydrophilic and hydrophobic elements within their molecular structure. In addition, an effective liquid-liquid extraction method (98% recovery) was employed surpassing previously used extraction methods. The analysis of nanoparticle-treated cells showed an initial rise in the analyte intracellular concentration followed by a maximum and a somewhat more gradual decrease of the intracellular concentration. The observed intracellular depletion of the gemini surfactants may be attributable to their bio-transformation into metabolites and exocytosis from the host cells. Obtained cellular data showed a pattern that grants additional investigations, evaluating metabolite formation and assessing the subcellular distribution of tested compounds.

  9. Gemini vitamin D analog suppresses ErbB2-positive mammary tumor growth via inhibition of ErbB2/AKT/ERK signaling.

    PubMed

    Lee, Hong Jin; So, Jae-Young; DeCastro, Andrew; Smolarek, Amanda; Paul, Shiby; Maehr, Hubert; Uskokovic, Milan; Suh, Nanjoo

    2010-07-01

    Numerous synthetic vitamin D analogs have been studied for their effects on the prevention and treatment of breast cancer. However, the inhibitory effects of naturally occurring 1alpha,25-dihydroxyvitamin D3 or its synthetic analogs on ErbB2 overexpressing mammary tumorigenesis have not been reported. Gemini vitamin D analogs are novel synthetic vitamin D derivatives with a unique structure of two six-carbon chains at C-20. We have previously shown that Gemini vitamin D analogs significantly inhibited carcinogen-induced estrogen receptor (ER)-positive mammary tumorigenesis and reduced ER-negative MCF10DCIS.com xenograft tumor growth without hypercalcemic toxicity. In the present study, we have determined the inhibitory effect of a potent Gemini vitamin D analog BXL0124 (1alpha,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol) on the ErbB2/Her-2/neu overexpressing mammary tumorigenesis. The Gemini BXL0124 inhibits ErbB2-positive mammary tumor growth and down-regulates the phosphorylation of ErbB2, ERK and AKT in tumors of MMTV-ErbB2/neu transgenic mice. These effects of Gemini BXL0124 in vivo were confirmed by using the ErbB2 overexpressing tumor cells derived from the mammary tumors of MMTV-ErbB2/neu mice. In conclusion, the Gemini vitamin D analog BXL0124 inhibits the growth of ErbB2 overexpressing mammary tumors through regulating the ErbB2/AKT/ERK signaling pathways, suggesting that Gemini vitamin D analog may be considered for translational studies.

  10. SN 1987A after 18 Years: Mid-Infrared GEMINI and SPITZER Observations of the Remnant

    NASA Technical Reports Server (NTRS)

    Bouchet, Patrice; Dwek, Eli; Danziger, John; Arendt, Richard G.; DeBuizer, James M.; Park, Sangwook; Suntzeff, Nicholas B.; Kirshner, Robert P.; Challis, Peter

    2007-01-01

    We present high resolution 11.7 and 18.3 micron mid-IR images of SN 1987A obtained on day 6526 since the explosion with the Thermal-Region Camera and Spectrograph (T-ReCS) attached to the Gemini South 8m telescope. The 11.7 micron flux has increased significantly since our last observations on day 6067. The images clearly show that all the emission arises from the equatorial ring (ER). Nearly contemporaneous spectra obtained on day 6184 with the MIPS at 24 micron, on day 6130 with the IRAC in 3.6- 8 micron region, and on day 6190 with the IRS in the 12-37 micron instruments on board the Spitzer Space Telescope's show that the emission consists of thermal emission from silicate dust that condensed out in the red giant wind of the progenitor star. The dust temperature is 1662(sup +18) (sub -12) K, and the emitting dust mass is (2.6(sup +2.0 (sub -1.4)) x 10 (exp -6) M(solar). Lines of [Ne II] 12.82 micron and [Ne III] 15.56 pm are clearly present in the Spitzer spectrum, as well as a weak [Si II] 3 34.8 micron line. We also detect two lines near 26 micron which we tentatively ascribe to [Fe II] 25.99 pm and [0 IV] 25.91 micron. Comparison of the mid-IR Gemini 11.7 micron image with X-ray images obtained by Chandra, UV-optical images obtained by HST, and radio synchrotron images obtained by the ATCA show generally good correlation of the images across all wavelengths. Because of the limited resolution of the mid-IR images we cannot uniquely determine the location. or heating mechanism of the dust giving rise to the emission. The dust could be collisionally heated by the X-ray emitting plasma, providing a unique diagnostic of plasma conditions. Alternatively, the dust could be radiatively heated in the dense UV-optical knots that are overrun by the advancing supernova blast wave. In either case the dust-to-gas mass ratio in the circumstellar medium around the supernova is significantly lower than that in the general interstellar medium of the LMC, suggesting either a

  11. Large-scale, low-cost synthesis of monodispersed gold nanorods using a gemini surfactant

    NASA Astrophysics Data System (ADS)

    Xu, Yong; Zhao, Yang; Chen, Lei; Wang, Xuchun; Sun, Jianxia; Wu, Haihua; Bao, Feng; Fan, Jian; Zhang, Qiao

    2015-04-01

    In this work, we demonstrate that monodispersed gold nanorods (AuNRs) can be obtained in a large-scale and cost-effective way. By using an industrial grade gemini surfactant (P16-8-16), the cost of the synthesis of high-quality AuNRs can be significantly reduced by 90%. The synthesis can be scaled up to over 4 L. The aspect ratio of AuNRs can be well tuned from ~2.4 to ~6.3, resulting in a wide tunability of the SPR properties. Systematic studies reveal that P16-8-16 could have a dual function: it can not only act as a capping ligand to stabilize AuNRs but also it can pre-reduce Au3+ to Au+ by the unsaturated C&z.dbd;C bond. Furthermore, the shape of AuNRs can be tailored from straight nanorods to ``dog-bones'' by simply varying the concentration of the surfactant. A mechanistic study shows that the shape change can be attributed to the presence of excess bromide ions because of the complex effect between bromide ions and gold ions. This work will not only help to achieve the industrial production of AuNRs, but also promote research into practical applications of various nanomaterials.In this work, we demonstrate that monodispersed gold nanorods (AuNRs) can be obtained in a large-scale and cost-effective way. By using an industrial grade gemini surfactant (P16-8-16), the cost of the synthesis of high-quality AuNRs can be significantly reduced by 90%. The synthesis can be scaled up to over 4 L. The aspect ratio of AuNRs can be well tuned from ~2.4 to ~6.3, resulting in a wide tunability of the SPR properties. Systematic studies reveal that P16-8-16 could have a dual function: it can not only act as a capping ligand to stabilize AuNRs but also it can pre-reduce Au3+ to Au+ by the unsaturated C&z.dbd;C bond. Furthermore, the shape of AuNRs can be tailored from straight nanorods to ``dog-bones'' by simply varying the concentration of the surfactant. A mechanistic study shows that the shape change can be attributed to the presence of excess bromide ions because of the

  12. Unraveling the interaction of hemoglobin with a biocompatible and cleavable oxy-diester-functionalized gemini surfactant.

    PubMed

    Akram, Mohd; Anwar, Sana; Bhat, Imtiyaz Ahmad; Kabir-Ud-Din

    2017-03-01

    Surfactant-protein mixtures have attracted considerable research interest in recent years at the interface of chemical biology and medicinal chemistry. Herein, the interaction between a green gemini surfactant (C16-E2O-C16) and a redox protein hemoglobin was examined through a series of in vitro experimental techniques with an attempt to provide a comprehensive knowledge of the surfactant-protein binding interactions. Quantitative appraisal of the fluorescence/CV data showed that the binding of C16-E2O-C16 to Hb leads to the formation of thermodynamically favorable non-covalent adduct with 1:1 stoichiometry. UV-vis spectra demonstrated that the effect of C16-E2O-C16 on Hb is highly concentration dependent. Far-UV and near-UV CD spectra together elucidated the formation of molten globule state of Hb upon C16-E2O-C16 addition. Temperature dependent CD explicated the effect of C16-E2O-C16 on the thermal stability of Hb. Furthermore, the structural investigation of Hb via pyrene/synchronous/three-dimensional fluorescence and FT-IR spectroscopy provided the complementary information related to its microenvironmental and conformational changes. Computational studies delineated that C16-E2O-C16 binds in the vicinity of β-37 Trp at the α1β2 interface of Hb. Overall, this study is expected to clarify the binding mechanism between Hb/other congeners and surfactant at the molecular level that are known to have immense potential in biomedical and industrial areas.

  13. NEMA NU 2-2001 performance testing of a Philips Gemini GXL PET/CT scanner.

    PubMed

    Sathiakumar, Chithradevi; Som, Seu; Eberl, Stefan; Lin, Peter

    2010-06-01

    Post installation acceptance testing is vital to demonstrate that the equipment meets the vendor's specification and is suitable for clinical studies. The test procedures described in the NEMA NU 2-2001 document form the basis of vendor performance specifications of PET scanners and hence are also appropriate for acceptance testing. Initial installation performance tests of the Philips Gemini GXL PET/CT scanner installed at Liverpool Hospital revealed that the peak noise equivalent count rate (NECR) measurement of 57.5 kcps was substantially lower than the specification of 70 kcps and the scatter fraction of 38.5% was 10% higher than the specification of

  14. Dynamic Model Investigation of a 1/20 Scale Gemini Spacecraft in the Langley Spin Tunnel

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Dynamic Model Investigation of a 1/20 Scale Gemini Spacecraft in the Langley Spin Tunnel. The investigation was conducted in the Langley spin tunnel. The tunnel is an atmospheric wind tunnel with a vertically rising airstream in the test section and a maximum airspeed of approximately 90 feet per second. For this investigation, the model was hand launched into the vertically rising airstream. At times the model, both with and without a drogue parachute, was launched gently with as little disturbance as possible to determine what motions of the spacecraft were self-excited. At other times, the spacecraft with pre-deployed drogue parachute was launched into various spinning motions to determine the effectiveness of the drogue parachute in terminating these spinning motions. During drogue-parachute deployment tests, the spacecraft was launched into various spinning and tumbling motions and the drogue parachute was deployed. The motions of the model were photographed with a motion-picture camera, and some of the film records were read to obtain typical time histories of the model motion. The angles of attack indicated in the time histories presented are believed to be accurate within +/-1 degree. The mass and dimensional characteristics of the dynamic model are believed to be measured to an accuracy of: +/-1 percent for the weight, +/-1 percent for z(sub cg)/d, +/-15 percent for x (sub cg), and +/-5 percent for the moments of inertia. The towline and bridle-line lengths were simulated to an accuracy of +/-1 foot full scale. [Entire movie available on DVD from CASI as Doc ID 20070030985. Contact help@sti.nasa.gov

  15. Calibrating IR optical densities for the Gemini Planet Imager extreme adaptive optics coronagraph apodizers

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, Anand; Soummer, Rémi; Carr, G. Lawrence; Dorrer, Christophe; Bolognesi, Allen; Zimmerman, Neil; Oppenheimer, Ben R.; Roberts, Robin; Greenbaum, Alexandra

    2009-08-01

    High contrast imaging sometimes uses apodized masks in coronagraphs to suppress diffracted starlight from a bright source in order to observe its environs. Continuously graded opacity material and metallic half-tone dots are two possible apodizers fabrication techniques. In the latter approach if dot sizes are comparable to the wavelength of the light, surface plasmon effects can complicate the optical density (OD) vs. superficial dot density relation. OD can also be a complicated function of wavelength. We measured half-tone microdot screens' and continuous materials' transmissions. Our set-up replicated the f/ 64 optical configuration of the Gemini Planet Imager's Apodized Pupil Lyot Coronagraph pupil plane, where we plan to place our pupil plane masks. Our half-tone samples were fabricated with 2, 5, and 10 micron dot sizes, our continuous greyscale was High Energy Electron Beam Sensitive (HEBS) glass (Canyon Materials Inc.). We present optical density (OD) vs. wavelength curves for our half-tone and continuous greyscale samples 1.1 - 2.5 μm wavelength range. Direct measurements of the beam intensity in the far field using a Fourier Transform Infrared Spectrograph on Beamline U4IR at Brookhaven National Laboratory's National Synchrotron Light Source (NSLS) provided transmission spectra of test patches and apodizers. We report the on-axis IR transmission spectra through screens composed of metallic dots that are comparable in size with the wavelength of the light used, over a range of optical densities. We also measured departures from simple theory describing the array of satellite spots created by thin periodic grids in the pupil of the system. Such spots are used for photometry and astrometry in coronagraphic situations. Our results pertain to both ground and space based coronagraphs that use spatially variable attenuation, typically in focal plane or pupil plane masks.

  16. Gemini Planet Imager observations of the AU Microscopii debris disk: Asymmetries within one arcsecond

    SciTech Connect

    Wang, Jason J.; Graham, James R.; Pueyo, Laurent; Nielsen, Eric L.; Millar-Blanchaer, Max; De Rosa, Robert J.; Kalas, Paul; Ammons, S. Mark; Bulger, Joanna; Cardwell, Andrew; Chen, Christine; Chiang, Eugene; Chilcote, Jeffrey K.; Doyon, René; Draper, Zachary H.; Duchêne, Gaspard; Fitzgerald, Michael P.; Goodsell, Stephen J.; Greenbaum, Alexandra Z.; Hartung, Markus; Hibon, Pascale; Hinkley, Sasha; Hung, Li -Wei; Ingraham, Patrick; Larkin, James E.; Macintosh, Bruce; Maire, Jerome; Marchis, Franck; Marois, Christian; Matthews, Brenda C.; Morzinski, Katie M.; Oppenheimer, Rebecca; Patience, Jenny; Perrin, Marshall D.; Rajan, Abhijith; Rantakyrö, Fredrik T.; Sadakuni, Naru; Serio, Andrew; Sivaramakrishnan, Anand; Soummer, Rémi; Thomas, Sandrine; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2015-09-23

    We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1'' (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side at similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1'' when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ~50 mas between 0farcs4 and 1farcs2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ~4 MJup planets at 4 AU. Lastly, we detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.

  17. Gemini Planet Imager observations of the AU Microscopii debris disk: Asymmetries within one arcsecond

    DOE PAGES

    Wang, Jason J.; Graham, James R.; Pueyo, Laurent; ...

    2015-09-23

    We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1'' (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side atmore » similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1'' when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ~50 mas between 0farcs4 and 1farcs2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ~4 MJup planets at 4 AU. Lastly, we detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.« less

  18. DETECTABILITY OF EXOPLANETS IN THE {beta} PIC MOVING GROUP WITH THE GEMINI PLANET IMAGER

    SciTech Connect

    Kataria, Tiffany; Simon, Michal

    2010-07-15

    We model the detectability of exoplanets around stars in the {beta} Pic Moving Group (BPMG) using the Gemini Planet Imager (GPI), a coronagraphic instrument designed to detect companions by imaging. Members of the BPMG are considered promising targets for exoplanet searches because of their youth ({approx}12 Myr) and proximity (median distance {approx}35 pc). We wrote a modeling procedure to generate hypothetical companions of given mass, age, eccentricity, and semi-major axis, and place them around BPMG members that fall within the V-band range of the GPI. We count companions lying within the GPI's field of view and H-band fluxes that have a host-companion flux ratio placing them within its sensitivity as possible detections. The fraction of companions that could be detected depends on their brightness at 12 Myr, and hence formation mechanism, and on their distribution of semi-major axes. We used brightness models for formation by disk instability and core-accretion. We considered the two extreme cases of the semi-major axis distribution-the log-normal distribution of the nearby F- and G-type stars and a power-law distribution indicated by the exoplanets detected by the radial velocity technique. We find that the GPI could detect exoplanets of all the F and G spectral type stars in the BPMG sample with a probability that depends on the brightness model and semi-major axis distribution. At spectral type K-M1, exoplanet detectability depends on brightness and hence distance of the host star. GPI will be able to detect the companions of M stars later than M1 only if they are closer than 10 pc. Of the four A stars in the BPMG sample, only one has a V-band brightness in the range of GPI; the others are too bright.

  19. The Unprecedented Metamorphosis of Supernova 2014C: New Insights from New Observations by HST and Gemini

    NASA Astrophysics Data System (ADS)

    Milisavljevic, Dan; Patnaude, Daniel; Margutti, Raffaella; Kamble, Atish; Raymond, John C.; Bietenholz, Michael; Parrent, Jerod; Kirshner, Robert; Challis, Peter; Fransson, Claes; Fong, Wen-fai; Zauderer, Ashley

    2017-01-01

    Recent observations of major eruptions preluding supernova explosions within one year of core collapse have challenged long held notions of stellar evolution. These eruptions are not easily explained by our current understanding of the physical mechanisms that drive mass loss in evolved massive stars, and may have significant ramifications for fields of research that depend on the predictions of stellar evolution models. Our group recently discovered a remarkable event — SN 2014C — in the nearby spiral galaxy NGC 7331 (D ˜ 15.8 Mpc) whose classification underwent a metamorphosis from a hydrogen-poor type Ib explosion to a hydrogen-rich type IIn. The transformation was the result of a rarely observed delayed interaction between a stripped-envelope supernova and a massive shell of circumstellar material located ˜5x1016 cm from the explosion site. Here we present new observations of SN 2014C obtained with the Hubble Space Telescope and the Gemini-N telescope that are part of a larger multi-wavelength Chandra/NuSTAR/VLA/SMA monitoring campaign. Our late-time ultraviolet/optical/near-infrared spectroscopy probes the composition, density, temperature, and speed of the emitting gas, and our high-resolution ultraviolet/optical images map out the nearby stellar environment. We find that the mass loss experienced by the progenitor system was strongly asymmetric, and that it was potentially driven by interaction between the progenitor star and a close binary companion. Our work supports the view that delays of ˜1000 yr between eruptive mass loss and core collapse are possible in massive stars that have been stripped of their hydrogen envelopes.

  20. Spectroscopic Characterization of HD 95086 b with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    De Rosa, Robert J.; Rameau, Julien; Patience, Jenny; Graham, James R.; Doyon, René; Lafrenière, David; Macintosh, Bruce; Pueyo, Laurent; Rajan, Abhijith; Wang, Jason J.; Ward-Duong, Kimberly; Hung, Li-Wei; Maire, Jérôme; Nielsen, Eric L.; Ammons, S. Mark; Bulger, Joanna; Cardwell, Andrew; Chilcote, Jeffrey K.; Galvez, Ramon L.; Gerard, Benjamin L.; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Ingraham, Patrick; Johnson-Groh, Mara; Kalas, Paul; Konopacky, Quinn M.; Marchis, Franck; Marois, Christian; Metchev, Stanimir; Morzinski, Katie M.; Oppenheimer, Rebecca; Perrin, Marshall D.; Rantakyrö, Fredrik T.; Savransky, Dmitry; Thomas, Sandrine

    2016-06-01

    We present new H (1.5-1.8 μm) photometric and K 1 (1.9-2.2 μm) spectroscopic observations of the young exoplanet HD 95086 b obtained with the Gemini Planet Imager. The H-band magnitude has been significantly improved relative to previous measurements, whereas the low-resolution K 1 (λ /δ λ ≈ 66) spectrum is featureless within the measurement uncertainties and presents a monotonically increasing pseudo-continuum consistent with a cloudy atmosphere. By combining these new measurements with literature L\\prime photometry, we compare the spectral energy distribution (SED) of the planet to other young planetary-mass companions, field brown dwarfs, and to the predictions of grids of model atmospheres. HD 95086 b is over a magnitude redder in {K}1-L\\prime color than 2MASS J12073346-3932539 b and HR 8799 c and d, despite having a similar L\\prime magnitude. Considering only the near-infrared measurements, HD 95086 b is most analogous to the brown dwarfs 2MASS J2244316+204343 and 2MASS J21481633+4003594, both of which are thought to have dusty atmospheres. Morphologically, the SED of HD 95086 b is best fit by low temperature ({T}{{eff}} = 800-1300 K), low surface gravity spectra from models which simulate high photospheric dust content. This range of effective temperatures is consistent with field L/T transition objects, but the spectral type of HD 95086 b is poorly constrained between early L and late T due to its unusual position the color-magnitude diagram, demonstrating the difficulty in spectral typing young, low surface gravity substellar objects. As one of the reddest such objects, HD 95086 b represents an important empirical benchmark against which our current understanding of the atmospheric properties of young extrasolar planets can be tested.

  1. GEMINI PLANET IMAGER OBSERVATIONS OF THE AU MICROSCOPII DEBRIS DISK: ASYMMETRIES WITHIN ONE ARCSECOND

    SciTech Connect

    Wang, Jason J.; Graham, James R.; De Rosa, Robert J.; Kalas, Paul; Chiang, Eugene; Duchêne, Gaspard; Pueyo, Laurent; Chen, Christine; Greenbaum, Alexandra Z.; Nielsen, Eric L.; Millar-Blanchaer, Max; Ammons, S. Mark; Bulger, Joanna; Cardwell, Andrew; Goodsell, Stephen J.; Chilcote, Jeffrey K.; Doyon, René; Draper, Zachary H.; Esposito, Thomas M.; Fitzgerald, Michael P.; and others

    2015-10-01

    We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1″ (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side at similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1″ when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ∼50 mas between 0.″4 and 1.″2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ∼4 M{sub Jup} planets at 4 AU. We detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.

  2. The Gemini NICI planet-finding campaign: the orbit of the young exoplanet β Pictoris b

    SciTech Connect

    Nielsen, Eric L.; Liu, Michael C.; Chun, Mark; Ftaclas, Christ; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.; Kuchner, Marc J.; Rodigas, Timothy J.; Toomey, Douglas W.

    2014-10-20

    We present new astrometry for the young (12-21 Myr) exoplanet β Pictoris b taken with the Gemini/NICI and Magellan/MagAO instruments between 2009 and 2012. The high dynamic range of our observations allows us to measure the relative position of β Pic b with respect to its primary star with greater accuracy than previous observations. Based on a Markov Chain Monte Carlo analysis, we find the planet has an orbital semi-major axis of 9.1{sub −0.5}{sup +5.3} AU and orbital eccentricity <0.15 at 68% confidence (with 95% confidence intervals of 8.2-48 AU and 0.00-0.82 for semi-major axis and eccentricity, respectively, due to a long narrow degenerate tail between the two). We find that the planet has reached its maximum projected elongation, enabling higher precision determination of the orbital parameters than previously possible, and that the planet's projected separation is currently decreasing. With unsaturated data of the entire β Pic system (primary star, planet, and disk) obtained thanks to NICI's semi-transparent focal plane mask, we are able to tightly constrain the relative orientation of the circumstellar components. We find the orbital plane of the planet lies between the inner and outer disks: the position angle (P.A.) of nodes for the planet's orbit (211.8 ± 0.°3) is 7.4σ greater than the P.A. of the spine of the outer disk and 3.2σ less than the warped inner disk P.A., indicating the disk is not collisionally relaxed. Finally, for the first time we are able to dynamically constrain the mass of the primary star β Pic to 1.76{sub −0.17}{sup +0.18} M {sub ☉}.

  3. Application of peptide gemini surfactants as novel solubilization surfactants for photosystems I and II of cyanobacteria.

    PubMed

    Koeda, Shuhei; Umezaki, Katsunari; Noji, Tomoyasu; Ikeda, Atsushi; Kawakami, Keisuke; Kondo, Masaharu; Yamamoto, Yasushi; Shen, Jian-Ren; Taga, Keijiro; Dewa, Takehisa; Ito, Shigeru; Nango, Mamoru; Tanaka, Toshiki; Mizuno, Toshihisa

    2013-09-17

    We designed novel peptide gemini surfactants (PG-surfactants), DKDKC12K and DKDKC12D, which can solubilize Photosystem I (PSI) of Thermosynecoccus elongatus and Photosystem II (PSII) of Thermosynecoccus vulcanus in an aqueous buffer solution. To assess the detailed effects of PG-surfactants on the original supramolecular membrane protein complexes and functions of PSI and PSII, we applied the surfactant exchange method to the isolated PSI and PSII. Spectroscopic properties, light-induced electron transfer activity, and dynamic light scattering measurements showed that PSI and PSII could be solubilized not only with retention of the original supramolecular protein complexes and functions but also without forming aggregates. Furthermore, measurement of the lifetime of light-induced charge-separation state in PSI revealed that both surfactants, especially DKDKC12D, displayed slight improvement against thermal denaturation below 60 °C compared with that using β-DDM. This degree of improvement in thermal resistance still seems low, implying that the peptide moieties did not interact directly with membrane protein surfaces. By conjugating an electron mediator such as methyl viologen (MV(2+)) to DKDKC12K (denoted MV-DKDKC12K), we obtained derivatives that can trap the generated reductive electrons from the light-irradiated PSI. After immobilization onto an indium tin oxide electrode, a cathodic photocurrent from the electrode to the PSI/MV-DKDKC12K conjugate was observed in response to the interval of light irradiation. These findings indicate that the PG-surfactants DKDKC12K and DKDKC12D provide not only a new class of solubilization surfactants but also insights into designing other derivatives that confer new functions on PSI and PSII.

  4. Shocks and star formation in Stephan's Quintet. I. Gemini spectroscopy of Hα-bright knots

    SciTech Connect

    Konstantopoulos, I. S.; Cluver, M. E.; Appleton, P. N.; Guillard, P.; Trancho, G.; Bastian, N.; Charlton, J. C.; Fedotov, K.; Gallagher, S. C.; Smith, L. J.; Struck, C. J.

    2014-03-20

    We present a Gemini-GMOS spectroscopic study of Hubble Space Telescope (HST)-selected Hα-emitting regions in Stephan's Quintet (HCG 92), a nearby compact galaxy group, with the aim of disentangling the processes of shock-induced heating and star formation in its intra-group medium. The ≈40 sources are distributed across the system, but most densely concentrated in the ∼kiloparsec-long shock region. Their spectra neatly divide them into narrow- and broad-line emitters, and we decompose the latter into three or more emission peaks corresponding to spatial elements discernible in HST imaging. The emission-line ratios of the two populations of Hα-emitters confirm their nature as H II regions (90% of the sample) or molecular gas heated by a shock front propagating at ≲300 km s{sup –1}. Their redshift distribution reveals interesting three-dimensional structure with respect to gas-phase baryons, with no H II regions associated with shocked gas, no shocked regions in the intruder galaxy NGC 7318B, and a sharp boundary between shocks and star formation. We conclude that star formation is inhibited substantially, if not entirely, in the shock region. Attributing those H II regions projected against the shock to the intruder, we find a lopsided distribution of star formation in this galaxy, reminiscent of pileup regions in models of interacting galaxies. The Hα luminosities imply mass outputs, star formation rates, and efficiencies similar to nearby star-forming regions. Two large knots are an exception to this, being comparable in stellar output to the prolific 30 Doradus region. We also examine Stephan's Quintet in the context of compact galaxy group evolution, as a paradigm for intermittent star formation histories in the presence of a rich, X-ray-emitting intra-group medium. All spectra are provided as supplemental materials.

  5. Dissolution and regeneration of hide powder/cellulose composite in Gemini imidazolium ionic liquid.

    PubMed

    Wang, Guowei; Guo, Jiarong; Zhuang, Linghua; Wang, Yan; Xu, Bin

    2015-05-01

    Gemini imidazolium ionic liquid, 3,3'-[1,2-ethanediylbis (oxy-2,1-ethanediyl)]-bis[1-methyl-imidazolium]-dibromide ([C6O2(mim)2][Br]2), was used for the dissolution and regeneration of white hide powder (from pigskin), and blend white hide powder with cellulose for the easy production of white hide powder/cellulose composite. Dissolution performance of white hide powder in [C6O2(mim)2][Br]2 was studied. The native white hide powder and [C6O2(mim)2][Br]2 regenerated white hide powder were characterized by FT-IR, XRD, DSC-TG and FE-SEM. The results showed that [C6O2(mim)2][Br]2 was a good solvent to white hide powder. The dissolution time was 55 min when the white hide powder was 8% at 120°C. The dissolution time of [C6O2(mim)2][Br]2 for white hide powder was shorter than those of common ionic liquids. The triple helical structure of white hide powder was partly destroyed during [C6O2(mim)2][Br]2 dissolution. The possible mechanism of white hide powder dissolution in [C6O2(mim)2][Br]2 and the regeneration of white hide powder in methanol had been proposed. White hide powder/cellulose composites were successfully dissolved in [C6O2(mim)2][Br]2. The performance of white hide powder/cellulose film was measured by FT-IR and TG. The tensile strength, and elongation at break of white hide powder/cellulose composite films were tested. This work demonstrated that the white hide powder/cellulose composite exhibited some potential in collagen-based tissue engineering.

  6. The Gemini NICI Planet-Finding Campaign: The Offset Ring of HR 4796 A

    NASA Technical Reports Server (NTRS)

    Wahhaj, Zahed; Liu, Michael C.; Biller, Beth A.; Nielsen, Eric L.; Hayward, Thomas L.; Kuchner, Marc J.; Close, Laird M.; Chun, Mark; Ftaclas, Christ; Toomey, Douglas W.

    2014-01-01

    We present J, H, CH4 short (1.578 micrometers), CH4 long (1.652 micrometers) and K(sub s)-band images of the dust ring around the 10 Myr old star HR 4796 A obtained using the Near Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1 m Telescope. Our images clearly show for the first time the position of the star relative to its circumstellar ring thanks to NICI's translucent focal plane occulting mask. We employ a Bayesian Markov chain Monte Carlo method to constrain the offset vector between the two. The resulting probability distribution shows that the ring center is offset from the star by 16.7 +/- 1.3 milliarcseconds along a position angle of 26 +/- 3deg, along the PA of the ring, 26.47 +/- 0.04deg. We find that the size of this offset is not large enough to explain the brightness asymmetry of the ring. The ring is measured to have mostly red reflectivity across the JHKs filters, which seems to indicate micron-sized grains. Just like Neptune's 3:2 and 2:1 mean-motion resonances delineate the inner and outer edges of the classical Kuiper belt, we find that the radial extent of the HR 4796 A and the Fomalhaut rings could correspond to the 3:2 and 2:1 mean-motion resonances of hypothetical planets at 54.7 AU and 97.7 AU in the two systems, respectively. A planet orbiting HR 4796 A at 54.7 AU would have to be less massive than 1.6 Jup mass so as not to widen the ring too much by stirring.

  7. Gemini planet imager observational calibration XII: photometric calibration in the polarimetry mode

    NASA Astrophysics Data System (ADS)

    Hung, Li-Wei; Bruzzone, Sebastian; Millar-Blanchaer, Maxwell A.; Wang, Jason J.; Arriaga, Pauline; Metchev, Stanimir; Fitzgerald, Michael P.; Sivaramakrishnan, Anand; Perrin, Marshall D.

    2016-08-01

    The Gemini Planet Imager (GPI) is a high-contrast instrument specially designed for direct imaging and spectroscopy of exoplanets and debris disks. GPI can also operate as a dual-channel integral field polarimeter. The instrument primarily operates in a coronagraphic mode which poses an obstacle for traditional photometric calibrations since the majority of on-axis starlight is blocked. To enable accurate photometry relative to the occulted central star, a diffractive grid in a pupil plane is used to create a set of faint copies, named satellite spots, of the occulted star at specified locations and relative intensities in the field of view. We describe the method we developed to perform the photometric calibration of coronagraphic observations in polarimetry mode using these fiducial satellite spots. With the currently available data, we constrain the calibration uncertainty to be <13%, but the actual calibration uncertainty is likely to be lower. We develop the associated calibration scripts in the GPI Data Reduction Pipeline, which is available to the public. For testing, we use it to photometrically calibrate the HD 19467 B and β Pic b data sets taken in the H-band polarimetry mode. We measure the calibrated flux of HD 19467 B and β Pic b to be 0:078+/-0:011 mJy and 4:87+/-0:73 mJy, both agreeing with other measurements found in the literature. Finally, we explore an alternative method which performs the calibration by scaling the photometry in polarimetry mode to the photometrically calibrated response in spectroscopy mode. By comparing the reduced observations in raw units, we find that observations in polarimetry mode are 1:03 0:01 brighter than those in spectroscopy mode.

  8. A new generation of nano-structured supramolecular solvents based on propanol/gemini surfactant for liquid phase microextraction.

    PubMed

    Feizi, Neda; Yamini, Yadollah; Moradi, Morteza; Karimi, Meghdad; Salamat, Qamar; Amanzadeh, Hatam

    2017-02-08

    A new supramolecular solvent (SUPRAS) made up of aggregates of gemini surfactant was introduced. A microextraction method, based on the SUPRAS followed with high performance liquid chromatography-ultraviolet detection, was applied for the determination of parabens in cosmetics, beverages and water samples. A SUPRAS is a nano-structured liquid made up of surfactant aggregates synthesized through a self-assembly process. In the present work, a new gemini-based SUPRAS was introduced. Methyl paraben (MP), ethyl paraben (EP), and propyl paraben (PP) were extracted on the basis of π-cation and Van der Waals interactions into the SUPRAS. The parameter affecting the extraction of target analytes (i.e., the amount of surfactant and volume of propanol as major components comprising the supramolecular solvent, sample solution pH, salt addition, ultrasonic and centrifugation time) were investigated and optimized by one-variable-at-a-time method. Under the optimum conditions, the preconcentration factors of 98, 143 and 156 were obtained for MP, EP and PP, respectively. The linearity ranged from 0.5 to 0.7-200 μg L(-1) with the correlation of determination of (R(2)) ≥ 0.9938. The gemini-based SUPRAS followed by HPLC-UV has been found to have excellent detection sensitivity with a limit of detection (LOD, S/N = 3) of 0.5 μg L(-1) for EP and PP, and 0.7 μg L(-1) for MP. Good recoveries over the range of 92.0-108.3% assured the accuracy of the amount of parabens distinguished in the non-spiked samples.

  9. Reaching the Diffraction Limit - Differential Speckle and Wide-Field Imaging for the Gemini-N Telescope

    NASA Technical Reports Server (NTRS)

    Scott, Nic J.; Howell, Steve; Horch, Elliott

    2016-01-01

    Speckle imaging allows telescopes to achieve di raction limited imaging performance. The technique requires cameras capable of reading out frames at a very fast rate, e ectively `freezing out' atmospheric seeing. The resulting speckles can be correlated and images reconstructed that are at the di raction limit of the telescope. These new instruments are based on the successful performance and design of the Di erential Speckle Survey Instrument (DSSI) [2, 1]. The instruments are being built for the Gemini-N and WIYN telescopes and will be made available to the community via the peer review proposal process. We envision their primary use to be validation and characterization of exoplanet targets from the NASA K2 and TESS missions and RV discovered exoplanets. Such targets will provide excellent follow-up candidates for both the WIYN and Gemini telescopes [3]. Examples of DSSI data are shown in the gures below. We expect similar data quality in speckle imaging mode with the new instruments. Additionally, both cameras will have a wide- eld mode and standard SDSS lters. They will be highly versatile instruments and it is that likely many other science programs will request time on the cameras. The limiting magnitude for speckle observations, will remain around 13-14th at WIYN and 16-17th at Gemini, while wide- eld, normal CCD imaging operation should be able to go to much fainter, providing usual CCD imaging and photometric capabilities. The instruments will also have high utility as scoring cameras for telescope engineering purposes, or other applications where high time resolution is needed. Instrument support will be provided, including a software pipeline that takes raw speckle data to fully reconstructed images.

  10. The Gemini Planet Imager Exoplanet Survey and the discovery of the young Jupiter analog 51 Eridani b

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce; Gemini Planet Imager Exoplanet Survey

    2016-01-01

    The Gemini Planet Imager Exoplanet Survey has been began in November 2014 and has surveyed more than 100 young nearby stars. I will present an updated status of the survey, including instrument performance and completeness limits. We reported our first new exoplanet discovery, the 20 Myr planet 51 Eri b, in August of 2015. J and H band spectra show that it is among the coolest and lowest-luminosity exoplanets yet imaged, with strong methane absorption and a luminosity consistent with low-entropy formation. I will give an overview of the planet's properties, and results from observations in the second half of 2015.

  11. The new Gemini Observatory archive: a fast and low cost observatory data archive running in the cloud

    NASA Astrophysics Data System (ADS)

    Hirst, Paul; Cardenes, Ricardo

    2016-08-01

    We have developed and deployed a new data archive for the Gemini Observatory. Focused on simplicity and ease of use, the archive provides a number of powerful and novel features including automatic association of calibration data with the science data, and the ability to bookmark searches. A simple but powerful API allows programmatic search and download of data. The archive is hosted on Amazon Web Services, which provides us excellent internet connectivity and significant cost savings in both operations and development over more traditional deployment options. The code is written in python, utilizing a PostgreSQL database and Apache web server.

  12. Diester-containing Zwitterionic Gemini Surfactants with Different Spacer and Its Impact on Micellization Properties and Viscosity of Aqueous Micellar Solution.

    PubMed

    Patil, Sachin Vasant; Patil, Sanyukta Arun; Pratap, Amit Prabhakar

    2016-09-01

    A series of diester containing zwitterionic gemini surfactants, N,N-dimethyl-N-alkyl-2-[[hydroxy (alkoxy) phosphinyl]oxy]-alkylammonium designated as C8(-)-S-Cn(+), S = 2 and 3, n = 12, 14 and 16, were synthesized and characterized by instrumental techniques namely FT-IR, (1)H NMR, (13)C NMR, (31)P NMR and Mass spectral studies. These new gemini surfactants further investigated for their various surfactant properties. The critical micelle concentration (cmc) and the effectiveness of surface tension reduction (Πcmc) were determined as a function of surfactant concentration by means of surface tension measurement. Micellization and viscosity properties were investigated by surface tension, electrical conductivity, dye micellization and rheology techniques. The findings of the aqueous surfactant system obtained were impacted by polarity, size and the nature of zwitterions as the surface. The thermodynamic and viscosity properties of these surfactants found to be based on the structures of gemini surfactants.

  13. Di-Peptide-Modified Gemini Surfactants as Gene Delivery Vectors: Exploring the Role of the Alkyl Tail in Their Physicochemical Behavior and Biological Activity.

    PubMed

    Al-Dulaymi, Mays A; Chitanda, Jackson M; Mohammed-Saeid, Waleed; Araghi, Hessamaddin Younesi; Verrall, Ronald E; Grochulski, Pawel; Badea, Ildiko

    2016-09-01

    The aim of this work was to elucidate the structure-activity relationship of new peptide-modified gemini surfactant-based carriers. Glycyl-lysine modified gemini surfactants that differ in the length and degree of unsaturation of their alkyl tail were used to engineer DNA nano-assemblies. To probe the optimal nitrogen to phosphate (N/P) ratio in the presence of helper lipid, in vitro gene expression and cell toxicity measurements were carried out. Characterization of the nano-assemblies was accomplished by measuring the particle size and surface charge. Morphological characteristics and lipid organization were studied by small angle X-ray scattering technique. Lipid monolayers were studied using a Langmuir-Blodgett trough. The highest activity of glycyl-lysine modified gemini surfactants was observed with the 16-carbon tail compound at 2.5 N/P ratio, showing a 5- to 10-fold increase in the level of reporter protein compared to the 12 and 18:1 carbon tail compounds. This ratio is significantly lower compared to the previously studied gemini surfactants with alkyl or amino- spacers. In addition, the 16-carbon tail compound exhibited the highest cell viability (85%). This high efficiency is attributed to the lowest critical micelle concentration of the 16-tail gemini surfactant and a balanced packing of the nanoparticles by mixing a saturated and unsaturated lipid together. At the optimal N/P ratio, all nanoparticles exhibited an inverted hexagonal lipid assembly. The results show that the length and nature of the tail of the gemini surfactants play an important role in determining the transgene efficiency of the delivery system. We demonstrated here that the interplay between the headgroup and the nature of tail is specific to each series, thus in the process of rational design, the contribution of the latter should be assessed in the appropriate context.

  14. Interaction of a cationic gemini surfactant with DNA and with sodium poly(styrene sulphonate) at the air/water interface: a neutron reflectometry study.

    PubMed

    Vongsetskul, T; Taylor, D J F; Zhang, J; Li, P X; Thomas, R K; Penfold, J

    2009-04-07

    The interactions between a dicationic gemini surfactant with a six-hydrocarbon spacer (1,2-bis(dodecyldimethyl-ammonio)hexane dibromide, C12C6C12Br2) and anionic polyelectrolyte DNA or sodium (polystyrene sulfonate) (NaPSS) at the air/solution interface have been studied and compared using neutron reflectometry together with surface tension. In the presence of the dichained cationic gemini surfactant, DNA and NaPSS display very different adsorption behaviors. The DNA/gemini mixtures show adsorption behavior very similar to that of DNA/C12TAB mixtures, with enhanced surfactant adsorption at low concentrations and thick structured layers at higher concentrations. However, for the NaPSS/gemini mixtures the amount of gemini at the surface is reduced relative to that in the absence of NaPSS at concentrations below the cmc. These differences in adsorption behavior are attributed to differences in the molecular structure and flexibility of the two polyanions. NaPSS is relatively hydrophobic and flexible enough to form bulk-phase polymer-micelle complexes with the gemini surfactant at low surfactant concentrations, whereas the adsorption of surface complexes is much less favorable because the dications on the gemini would require adjacent bulky pendant charges on the NaPSS to be oriented toward the surface. This would force the NaPSS to bend significantly whereas it is more favorable for the NaPSS to adopt an extended conformation at the surface. Thus, surfactant is actually removed from the surface to form bulk-phase complexes. In contrast with NaPSS, DNA has a far more rigid structure, and the charges on the backbone are at fixed intervals, factors that make the formation of surface DNA-monomer complexes much more favorable than bulk-phase DNA-micelle complexes. Finally, a short-chain sample of NaPSS consisting of only five to six segments adsorbs very strongly at the surface with the gemini to form more extensive layered structures than have previously been observed

  15. Gemini NorthNIRI Spectra of Pluto and Charon: Simultaneous Analysis of the Surface and Atmosphere

    NASA Technical Reports Server (NTRS)

    Cook, Jason C.; Cruikshank, Dale P.; Young, Leslie A.

    2014-01-01

    94035We report on our analysis of blended Pluto and Charon spectra over the wavelength range 1.4 to 2.5 m as obtained by the NIRI instrument on Gemini North on June 25-28, 2004. The data have a resolving power () around 1500 and a SNR around 200 per pixel. The observed blended spectra are compared to models that combine absorption from the solid ice on the surface using Hapke theory, and absorption from the gaseous atmosphere. We assume the spectrum is a combination of several spatially separate spectral units: a CH4-rich ice unit, a volatile unit (an intimate mixture of N2, CH4 and CO), and a Charon unit (H2O, ammonia hydrate and kaolinite). We test for the presence of hydrocarbons (i.e. C2H6) and nitriles (i.e. HCN) and examine cases where additional ices are present as either pure separate spatial units, mixed with the CH4-rich unit or part of the volatile unit. We conclude that 2-4 of Plutos surface is covered with pure-C2H6 and our identification of C2H6 is significantly strengthened when absorption due to gaseous CH4 is included. The inclusion of Plutos atmosphere demonstrates that low-resolution, high-SNR observations are capable of detecting Plutos atmosphere during a time when Plutos atmosphere may have been undergoing rapid changes (1988-2002) and no high-resolution spectra were obtained. In particular, we identify features at 1.665 and 2.317 m as the Q-branch of the 23 and 3+4 bands of gaseous CH4, respectively. The later band is also evident in many previously published spectra of Pluto. Our analysis finds it is unnecessary to include 13CO to explain the depth of the 2.405 m, which has been previously suggested to be a spectral blended with C2H6, but we cannot definitively rule out its presence. Funding for this work (Cook) has been provided by a NASA-PATM grant.

  16. Gemini and Keck Observations of Slowly Rotating, Bilobate Active Asteroid (300163)

    NASA Astrophysics Data System (ADS)

    Waniak, Waclaw; Drahus, Michal

    2016-10-01

    One of the most puzzling questions regarding Active Asteroids is the mechanism of their activation. While some Active Asteroids show protracted and often recurrent mass loss, consistent with seasonal ice sublimation, some other eject dust impulsively as a result of a catastrophic disruption (e.g. Jewitt et al. 2015, Asteroids IV, 221). It has been suggested that ice can be excavated from the cold near-surface interior by an impact (Hsieh & Jewitt 2006, Science 312, 561) or, for small objects susceptible to YORP torques, by near-critical spin rate (Sheppard & Trujillo 2014, AJ 149, 44). But impact and rapid spin can also cause a catastrophic disruption (e.g. Jewitt et al. 2015, Asteroids IV, 221). It therefore becomes apparent that the different types of mass loss observed in Active Asteroids can be best classified and understood based on the nucleus spin rates (Drahus et al. 2015, ApJL 802, L8), but unfortunately the rotation periods have been measured for a very limited number of these objects. With this in mind we have initiated a survey of light curves of small Active Asteroids on the largest ground-based optical telescopes. Here we present the results for (300163), also known as 288P and 2006 VW139, which is a small 2.6-km sized asteroid that exhibited a comet-like activity over 100 days in the second half of 2011 (Hsieh et al. 2012, ApJL 748, L15; Licandro et al. 2013, A&A 550, A17; Agarwal et al. 2016, AJ 151, 12). Using Keck/DEIMOS and Gemini/GMOS-S working in tandem on UT 2015 May 21-22 we have detected an inactive nucleus and measured a complete, dense, high-S/N rotational light curve. The light curve has a double-peaked period of 16 hours, an amplitude of 0.4 mag, and moderately narrow minima suggesting a bilobate or contact-binary shape. The long rotation period clearly demonstrates a non-rotational origin of activity of this object, consistent with an impact. Furthermore, among the five small Active Asteroids with known rotation periods (300163) is only

  17. THE GEMINI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF GIANT PLANETS AROUND DEBRIS DISK STARS

    SciTech Connect

    Wahhaj, Zahed; Liu, Michael C.; Nielsen, Eric L.; Ftaclas, Christ; Chun, Mark; Biller, Beth A.; Hayward, Thomas L.; Thatte, Niranjan; Tecza, Matthias; Shkolnik, Evgenya L.; Kuchner, Marc; Reid, I. Neill; De Gouveia Dal Pino, Elisabete M.; Gregorio-Hetem, Jane; Boss, Alan; Lin, Douglas N. C.; and others

    2013-08-20

    We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.''5 and 14.1 mag at 1'' separation. Follow-up observations of the 66 candidates with projected separation <500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known {beta} Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a {>=}5 M{sub Jup} planet beyond 80 AU, and <21% of debris disk stars have a {>=}3 M{sub Jup} planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly imaged planets as d {sup 2} N/dMda{proportional_to}m {sup {alpha}} a {sup {beta}}, where m is planet mass and a is orbital semi-major axis (with a maximum value of a{sub max}). We find that {beta} < -0.8 and/or {alpha} > 1.7. Likewise, we find that {beta} < -0.8 and/or a{sub max} < 200 AU. For the case where the planet frequency rises sharply with mass ({alpha} > 1.7), this occurs because all the planets detected to date have masses above 5 M{sub Jup}, but planets of lower mass could easily have been detected by our search. If we ignore the {beta} Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that <20% of debris disk stars have a {>=}3 M{sub Jup} planet beyond 10 AU, and {beta} < -0.8 and/or {alpha} < -1.5. Likewise, {beta} < -0.8 and/or a{sub max} < 125 AU. Our Bayesian constraints are not strong enough to reveal any dependence of the planet

  18. Gemini Planet Imager Exoplanet Survey: Key Results Two Years Into The Survey

    NASA Astrophysics Data System (ADS)

    Marchis, Franck; Rameau, Julien; Nielsen, Eric L.; De Rosa, Robert J.; Esposito, Thomas; Draper, Zachary H.; Macintosh, Bruce; Graham, James R.; GPIES

    2016-10-01

    The Gemini Planet Imager Exoplanet Survey (GPIES) is targeting 600 young, nearby stars using the GPI instrument. We report here on recent results obtained with this instrument from our team.Rameau et al. (ApJL, 822 2, L2, 2016) presented astrometric monitoring of the young exoplanet HD 95086 b obtained with GPI between 2013 and 2016. Efficient Monte Carlo techniques place preliminary constraints on the orbital parameters of HD 95086 b. Under the assumption of a coplanar planet-disk system, the periastron of HD 95086 b is beyond 51 AU. Therefore, HD 95086 b cannot carve the entire gap inferred from the measured infrared excess in the SED of HD 95086. Additional photometric and spectroscopic measurements reported by de Rosa et al. (2016, apJ, in press) showed that the spectral energy distribution of HD 95086 b is best fit by low temperature (T~800-1300 K), low surface gravity spectra from models which simulate high photospheric dust content. Its temperature is typical to L/T transition objects, but the spectral type is poorly constrained. HD 95086 b is an important exoplanet to test our models of atmospheric properties of young extrasolar planets.Direct detections of debris disk are keys to infer the collisional past and understand the formation of planetary systems. Two debris disks were recently studied with GPI:- Draper et al. (submitted to ApJ, 2016) show the resolved circumstellar debris disk around HD 111520 at a projected range of ~30-100 AU using both total and polarized H-band intensity. Structures in the disks such as a large brightness asymmetry and symmetric polarization fraction are seen. Additional data would confirm if a large disruption event from a stellar fly-by or planetary perturbations altered the disk density- Esposito et al. (submitted to ApJ, 2016) combined Keck NIRC2 data taken at 1.2-2.3 microns and GPI 1.6 micron total intensity and polarized light detections that probes down to projected separations less than 10 AU to show that the HD

  19. Thermodynamic properties of micellization of Sulfobetaine-type Zwitterionic Gemini Surfactants in aqueous solutions--a free energy perturbation study.

    PubMed

    Liu, Guoyu; Gu, Daming; Liu, Haiyan; Ding, Wei; Luan, Huoxin; Lou, Yanmin

    2012-06-01

    In this article, the validity and accuracy of the free energy perturbation (FEP) model used in a previous article for ionic liquid-type Gemini imidazolium surfactants (ILGISs) is further evaluated by using it to model the Enthalpy-entropy compensation of Sulfobetaine-type Zwitterionic Gemini Surfactants (SZGSs), with different carbon atoms of the hydrophobic group or the spacer chain length, in aqueous solutions. In the FEP model, the Gibbs free energy contributions to the driving force for micelle formation are computed using hydration data obtained from molecular dynamics simulations. According to the pseudo-phase separation model, the thermodynamic properties of micellization in aqueous solutions for SZGS were discussed. The results show that the micellization of SZGS in aqueous solutions is a spontaneous and entropy-driven process. It is linearly Enthalpy-entropy compensated and different from the micelle formation of ILGIS but similar to anionic surfactants. The compensation temperature was found to be (302±3)K which was lower than ILGIS. As the temperature rises, the micellization is easy initially but then becomes difficult with the unusual changes of enthalpy values from positive to negative. The contribution of entropy change to the micellization tends to decrease but the contribution of enthalpy change tends to increase. In particular, as the number carbon atoms in the alkyl chains and spacer chains are increased, the thermodynamic favorability and stability of the micelles both increase.

  20. THE GEMINI SPECTRAL LIBRARY OF NEAR-IR LATE-TYPE STELLAR TEMPLATES AND ITS APPLICATION FOR VELOCITY DISPERSION MEASUREMENTS

    SciTech Connect

    Winge, Claudia

    2009-11-01

    We present a spectroscopic library of late spectral type stellar templates in the near-IR range 2.15-2.42 {mu}m, at R = 5300-5900 resolution, oriented to support stellar kinematics studies in external galaxies, such as the direct determination of the masses of supermassive black holes in nearby active (or non-active) galaxies. The combination of high spectral resolution and state-of-the-art instrumentation available in 8 m class telescopes has made the analysis of circumnuclear stellar kinematics using the near-IR CO band heads one of the most used techniques for such studies, and this library aims to provide the supporting data sets required by the higher spectral resolution and larger spectral coverage currently achieved with modern near-IR spectrographs. Examples of the application for kinematical analysis are given for data obtained with two Gemini instruments, but the templates can be easily adjusted for use with other near-IR spectrographs at similar or lower resolution. The example data sets are also used to revisit the 'template mismatch' effect and the dependence of the velocity dispersion values obtained from the fitting process with the characteristics of the stellar templates. The library is available in electronic form from the Gemini Web pages.

  1. A gemini quaternary ammonium poly (ether ether ketone) anion-exchange membrane for alkaline fuel cell: design, synthesis, and properties.

    PubMed

    Si, Jiangju; Lu, Shanfu; Xu, Xin; Peng, Sikan; Xiu, Ruijie; Xiang, Yan

    2014-12-01

    To reconcile the tradeoff between conductivity and dimensional stability in AEMs, a novel Gemini quaternary ammonium poly (ether ether ketone) (GQ-PEEK) membrane was designed and successfully synthesized by a green three-step procedure that included polycondensation, bromination, and quaternization. Gemini quaternary ammonium cation groups attached to the anti-swelling PEEK backbone improved the ionic conductivity of the membranes while undergoing only moderate swelling. The grafting degree (GD) of the GQ-PEEK significantly affected the properties of the membranes, including their ion-exchange capacity, water uptake, swelling, and ionic conductivity. Our GQ-PEEK membranes exhibited less swelling (≤ 40 % at 25-70 °C, GD 67 %) and greater ionic conductivity (44.8 mS cm(-1) at 75 °C, GD 67 %) compared with single quaternary ammonium poly (ether ether ketone). Enhanced fuel cell performance was achieved when the GQ-PEEK membranes were incorporated into H2 /O2 single cells.

  2. In vitro disintegration of goat brain cystatin fibrils using conventional and gemini surfactants: Putative therapeutic intervention in amyloidoses.

    PubMed

    Bhat, Waseem Feeroze; Bhat, Imtiyaz Ahmad; Bhat, Sheraz Ahmad; Bano, Bilqees

    2016-12-01

    Many protein misfolding diseases in mammalian system are characterised by the accumulation of protein aggregates in amyloid fibrillar forms. Several therapeutic approaches include reduction in the production of the amyloidogenic form of proteins, increase in the clearance rate of misfolded or aggregated proteins, and direct inhibition of the self-assembly process have been explained. One of the possible remedial treatments for such disorders may be to identify molecules which are capable of either preventing formation of fibrils or disintegrating the formed fibrils. In this work, we have studied the effect of conventional surfactants; sodium dodecylsulphate (SDS), cetyl trimethylammonium bromide (CTAB) and dicationic gemini (16-4-16) surfactant on the disintegration of the goat brain cystatin (GBC) fibrils above their critical micelle concentrations (CMC) using ThT fluorescence, CD, TEM, Congo red and turbidity approaches. The results obtained are significant and showing the best disintegrating potency on GBC fibrils with gemini surfactant. The outcome from this work will aid in the development and/or design of potential inhibitory agents against amyloid deposits associated with amyloid diseases.

  3. The precision radial velocity error budget for the Gemini High-resolution Optical SpecTrograph (GHOST)

    NASA Astrophysics Data System (ADS)

    Ireland, Michael J.; Artigau, Étienne; Burley, Greg; Edgar, Michael; Margheim, Steve; Robertson, Gordon; Pazder, John; McDermid, Richard; Zhelem, Ross

    2016-08-01

    The Gemini High-resolution Optical SpecTrograph (GHOST) is a fiber fed spectrograph primarily designed for high efficiency and broad wavelength coverage (363 -1000nm), with an anticipated commissioning early in 2018. The primary scientific goal of the Precision Radial Velocity (PRV) mode will be follow-up of relatively faint (R>12) transiting exoplanet targets, especially from the TESS mission. In the PRV mode, the 1.2 arcsec diameter stellar image will be split 19 ways, combined in a single slit with a simultaneous Th/Xe reference source, dispersed at a resolving power of 80,000 and imaged onto two detectors. The spectrograph will be thermally stabilized in the Gemini pier laboratory, and modal noise will be reduced below other sources through the use of a fiber agitator. Unlike other precision high resolution spectrographs, GHOST will not be pressure controlled (although pressure will be monitored precisely), and there will be no double scrambler or shaped (e.g. octagonal) fibers. Instead, GHOST will have to rely on simultaneous two-color imaging of the slit and the simultaneous Th/Xe fiber to correct for variable fiber illumination and focal-ratio degradation. This configuration presents unique challenges in estimating a PRV error budget.

  4. Effect of head group polarity and spacer chain length on the aggregation properties of gemini surfactants in an aquatic environment.

    PubMed

    Borse, Mahendra; Sharma, Vikas; Aswal, V K; Goyal, P S; Devi, Surekha

    2005-04-01

    The aggregation behavior of cationic gemini surfactants with respect to variation in head group polarity and spacer length is studied through conductance, surface tension, viscosity, and small-angle neutron-scattering (SANS) measurements. The critical micellar concentration (cmc), average degree of micelle ionization (beta(ave)), minimum area per molecule of surfactant at the air-water interface (A(min)), surface excess concentration (gamma(max)), and Gibb's free energy of micellization (delta G(mic)) of the surfactants were determined from conductance and surface tension data. The aggregation numbers (N), dimensions of micelles (b/a), effective fractional charge per monomer (alpha), and hydration of micelles (h(E)) were determined from SANS and viscosity data, respectively. The increasing head group polarity of gemini surfactant with spacer chain length of 4 methylene units promotes micellar growth, leading to a decrease in cmc, beta(ave), and delta G(mic) and an increase in N and b/a. This is well supported by the observed increase in hydration (h(E)) of micelles with increase in aggregation number (N) and dimension (b/a) of micelle.

  5. Microwave-assisted modification on montmorillonite with ester-containing Gemini surfactant and its adsorption behavior for triclosan.

    PubMed

    Liu, Bo; Lu, Junxiang; Xie, Yu; Yang, Bin; Wang, Xiaoying; Sun, Runcang

    2014-03-15

    To obtain effective adsorbent that can remove emerging organic pollutant of triclosan (TCS) in aquatic environment, different ester-containing Gemini surfactant-modified MMT (EMMT) were prepared under microwave irradiation. The whole process was rapid, uniform, easy and energy-efficient. The structures and morphology of EMMT were characterized by XRD, TEM, FT-IR, SEM and TGA. The results revealed that the saturated intercalation amount of this surfactant was 0.8 times to cation exchange capacity (CEC) of MMT, and there was electrostatic interaction between ester-containing Gemini surfactant and MMT. In addition, they bound in the ways of intercalation, intercalation-adsorption or adsorption, which relied on the dosage of the surfactant. The surface of EMMT was hydrophobic, rough and fluffy, which contributed to its strong adsorption capacity. The adsorption equilibrium data of EMMT for TCS were fitted to Langmuir and Freundlich isothermal adsorption model. The result showed that Langmuir isothermal adsorption model could describe the adsorption behavior better, the adsorption behavior of TCS on EMMT was confirmed to a surface monolayer adsorption, and notably the theoretical maximum adsorption capacity was up to 133 mg/g. Therefore, this work lays important foundation on developing effective and safe absorbent materials for the treatment of emerging organic pollutants.

  6. Unusual pH-regulated surface adsorption and aggregation behavior of a series of asymmetric gemini amino-acid surfactants.

    PubMed

    Lv, Jing; Qiao, Weihong

    2015-04-07

    A new series of pH-regulated asymmetric amino-acid gemini surfactants N,N'-dialkyl-N,N'-diacetate ethylenediamine (Ace(m)-2-Ace(n)), differing by the asymmetric degree and length of the carbon tails (m = 8 and 10, n = 10, 12, 14, and 16), were synthesized in three steps. On the basis of pKa values obtained by pH titration, surface tension, fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements were performed to study the surface adsorption and aggregation properties in aqueous Ace(m)-2-Ace(n) solution. The new compounds have higher surface activity and better pH adaptability in comparison with that of symmetric gemini surfactants Ace(n)-2-Ace(n). The molecule behavior of Ace(m)-2-Ace(n) can be adjusted by either the hydrophobic group or the pH. With increasing alkyl chain length, the surface adsorption declines but its ability to form aggregates increases. We find that pH can promote the self-assembly transition of Ace(m)-2-Ace(n) from surfactant monomers to aggregates through protonation between H(+) and the tertiary nitrogen group. TEM data further confirm the pH-regulated molecular self-assembly process and the existence of vesicles at neutral or weak acidic pH. pH-recyclability is found to be reversible by pH-light transmittance recycle tests.

  7. High Precision Lightcurves of A Mutual Event of Transneptunian Binary (79360) Sila-Nunam From Gemini Observatory

    NASA Astrophysics Data System (ADS)

    Verbiscer, Anne J.; Grundy, W.; Benecchi, S.; Rabinowitz, D.; Skrutskie, M. F.

    2013-10-01

    Cold-classical Kuiper Belt binary (79360) Sila-Nunam is in the midst of a decade-long mutual event season in which its nearly equal-sized components occult and eclipse each other as viewed from Earth (Grundy et al. 2012 Icarus 220, 74-83). On 14 February 2013 UT, the Gemini Multi-Object Spectrograph (GMOS-N) camera at Gemini Observatory on Mauna Kea, Hawai'i imaged nearly an entire inferior event in which Nunam, the smaller of the two objects, eclipsed and occulted Sila. Alternating 200-second exposures in Sloan r' and i' filters continuously during the 9.3-hour event produced lightcurves containing information about sizes, colors, shapes, and albedo patterns on the system components. This mutual event is a rare opportunity to determine physical characteristics of a surface which has likely been unaltered since the time of Solar System formation. A. Verbiscer acknowledges support from NASA Planetary Astronomy. W. Grundy acknowledges support from NSF Planetary Astronomy.

  8. pH-induced motion control of self-propelled oil droplets using a hydrolyzable gemini cationic surfactant.

    PubMed

    Miura, Shingo; Banno, Taisuke; Tonooka, Taishi; Osaki, Toshihisa; Takeuchi, Shoji; Toyota, Taro

    2014-07-15

    Self-propelled motion of micrometer-sized substances has drawn much attention as an autonomous transportation system. One candidate vehicle is a chemically driven micrometer-sized oil droplet. However, to the best of our knowledge, there has been no report of a chemical reaction system controlling the three-dimensional motion of oil droplets underwater. In this study, we developed a molecular system that controlled the self-propelled motion of 4-heptyloxybenzaldehyde oil droplets by using novel gemini cationic surfactants containing carbonate linkages (2G12C). We found that, in emulsions containing sodium hydroxide, the motion time of the self-propelled oil droplets was longer in the presence of 2G12C than in the presence of gemini cationic surfactants without carbonate linkages. Moreover, in 2G12C solution, oil droplets at rest underwent unidirectional, self-propelled motion in a gradient field toward a higher concentration of sodium hydroxide. Even though they stopped within several seconds, they restarted in the same direction. 2G12C was gradually hydrolyzed under basic conditions to produce a pair of the corresponding monomeric surfactants, which exhibit different interfacial properties from 2G12C. The prolonged and restart motion of the oil droplets were explained by the increase in the heterogeneity of the interfacial tension of the oil droplets.

  9. FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini

    NASA Astrophysics Data System (ADS)

    Eikenberry, Stephen; Bandyopadhyay, Reba; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Charcos, Miguel; Corley, Richard; Dewitt, Curtis; Eriksen, John-David; Elston, Richard; Frommeyer, Skip; Gonzalez, Anthony; Hanna, Kevin; Herlevich, Michael; Hon, David; Julian, Jeff; Julian, Roger; Lasso, Nestor; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Raines, S. N.; Rambold, William; Rashkind, David; Warner, Craig; Leckie, Brian; Gardhouse, W. R.; Fletcher, Murray; Hardy, Tim; Dunn, Jennifer; Wooff, Robert; Pazder, John

    2012-09-01

    We report on the design, on-sky performance, and status of the FLAMINGOS-2 instrument - the fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048x2048- pixel HAWAII-2 0.9-2.4 μm detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3x1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-Instrument WaveFront Sensor subsystems. We also present the on-sky performance measured during acceptance testing in 2009, as well as current status of the project and future plans.

  10. FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini

    NASA Astrophysics Data System (ADS)

    Eikenberry, Stephen; Elston, Richard; Raines, S. Nicholas; Julian, Jeff; Hanna, Kevin; Warner, Craig; Julian, Roger; Bandyopadhyay, Reba; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Corley, Richard; Dewitt, Curtis; Eriksen, John-David; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael; Hon, David; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Rambold, William; Rashkin, David; Leckie, Brian; Gardhouse, W. Rusty; Fletcher, Murray; Hardy, Tim; Dunn, Jennifer; Wooff, Robert

    2008-07-01

    We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048×2048-pixel HAWAII-2 0.9-2.4 μm detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6×2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi- Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3×1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On- Instrument WaveFront Sensor subsystems. We also present the current status of the project and future plans, including on-sky delivery planned for late 2008.

  11. A two deformable-mirror concept to improve the laser efficiency of Gemini South MCAO (GeMS)

    NASA Astrophysics Data System (ADS)

    Béchet, Clémentine; Guesalaga, Andrés; Neichel, Benoit; Fesquet, Vincent; Guzman, Dani

    2013-12-01

    Gem's is the first laser-based multi-conjugate adaptive optics offeredto the astronomical community. Its asterism of 5 laser guide stars hasrecently proved to provide very uniform turbulence correction over the85''x85'' observation field, opening the new era of wide-field highangular resolution studies from the ground. Good AO performance requireshowever good wavefront sensing measurements from the laser guide stars,which directly depends on the quality of the laser spot image. Theoptimization of the lasers launched out of the telescope requires tofollow frequent and constraining calibrations and alignments procedures(quasi-static aberrations), in order to guarantee satisfying amplitudeand phase of the beam. These complex and time-consuming procedures willstrongly penalize the availability of Gem's.A laser beam shaping concept has been recently suggested to overcomesuch issues. It consists in applying, in the beam transfer optics, afield-conjugation thanks to 2 deformable mirrors. We review thisconcept. In particular, we discuss the criterion to be optimized and thedesired amplitude and phase shapes at the output of the Gemini beamtransfer optics. We deduce the control to be applied to the mirrors fromthe optimization of the signal-to-noise ratio of the wavefront sensingin Gem's. An iterative algorithm is used to estimate the phases, with aweighted least-squares unwrapper to avoid branch points. This algorithmefficiency is demonstrated with adequate beam shaping simulations.Discussion is made about how to implement such concept at Gemini.

  12. Effect of gemini (alkanediyl-α,ω-bis(dimethylcetylammonium bromide)) (16-s-16, s=4, 5, 6) surfactants on the interaction of ninhydrin with chromium-glycylphenylalanine.

    PubMed

    Kumar, Dileep; Rub, Malik Abdul; Akram, Mohd; Kabir-ud-Din

    2014-11-11

    The effect of gemini (alkanediyl-α,ω-bis(dimethylcetylammonium bromide)) (16-s-16, s=4, 5, 6) surfactants on the interaction of ninhydrin with chromium(III) complex of glycylphenylalanine ([Cr(III)-Gly-Phe]2+) has been investigated using UV-visible spectrophotometer at different temperatures. The order of reaction with respect to [Cr(III)-Gly-Phe]2+ is unity while it is fractional with respect to ninhydrin. Whereas, the values of rate constant (kψ) increase and leveling-off regions, like conventional single chain cetyltrimethylammonium bromide (CTAB) surfactant, were observed with geminis, later produces a third region of increasing kψ at higher gemini surfactant concentrations. This unusual third-region effect of the gemini micelles is assigned to changes in their micellar morphologies. The results obtained in micellar media were treated in terms of pseudo-phase model. The values of thermodynamic parameters (Ea, ΔH# and ΔS#) and binding constants (KA and KNin) have been evaluated.

  13. A Gemini/GMOS study of the physical conditions and kinematics of the blue compact dwarf galaxy Mrk 996

    NASA Astrophysics Data System (ADS)

    Telles, Eduardo; Thuan, Trinh X.; Izotov, Yuri I.; Carrasco, Eleazar R.

    2014-01-01

    Aims: We present an integral field spectroscopic study with the Gemini Multi-Object Spectrograph (GMOS) of the unusual blue compact dwarf (BCD) galaxy Mrk 996. Methods: We show through velocity and dispersion maps, emission-line intensity and ratio maps, and by a new technique of electron density limit imaging that the ionization properties of different regions in Mrk 996 are correlated with their kinematic properties. Results: From the maps, we can spatially distinguish a very dense high-ionization zone with broad lines in the nuclear region, and a less dense low-ionization zone with narrow lines in the circumnuclear region. Four kinematically distinct systems of lines are identified in the integrated spectrum of Mrk 996, suggesting stellar wind outflows from a population of Wolf-Rayet (WR) stars in the nuclear region, superposed on an underlying rotation pattern. From the intensities of the blue and red bumps, we derive a population of ~473 late nitrogen (WNL) stars and ~98 early carbon (WCE) stars in the nucleus of Mrk 996, resulting in a high N(WR)/N(O+WR) of 0.19. We derive, for the outer narrow-line region, an oxygen abundance 12 + log (O/H) = 7.94 ± 0.30 (~0.2 Z⊙) by using the direct Te method derived from the detected narrow [O iii]λ4363 line. The nucleus of Mrk 996 is, however, nitrogen-enhanced by a factor of ~20, in agreement with previous CLOUDY modeling. This nitrogen enhancement is probably due to nitrogen-enriched WR ejecta, but also to enhanced nitrogen line emission in a high-density environment. Although we have made use here of two new methods - principal component analysis (PCA) tomography and a method for mapping low- and high-density clouds - to analyze our data, new methodology is needed to further exploit the wealth of information provided by integral field spectroscopy. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative

  14. Line-by-line analysis of Neptune's near-IR spectrum observed with Gemini/NIFS and VLT/CRIRES

    NASA Astrophysics Data System (ADS)

    Irwin, P. G. J.; Lellouch, E.; de Bergh, C.; Courtin, R.; Bézard, B.; Fletcher, L. N.; Orton, G. S.; Teanby, N. A.; Calcutt, S. B.; Tice, D.; Hurley, J.; Davis, G. R.

    2014-01-01

    New line data describing the absorption of CH4 and CH3D from 1.26 to 1.71 μm (WKMC-80K, Campargue, A., Wang, L., Mondelain, D., Kassi, S., Bézard, B., Lellouch, E., Coustenis, A., de Bergh, C., Hirtzig, M., Drossart, P. [2012]. Icarus 219, 110-128) have been applied to the analysis of Gemini-N/NIFS observations of Neptune made in 2009 and VLT/CRIRES observations made in 2010. The new line data are found to greatly improve the fit to the observed spectra and present a considerable advance over previous methane datasets. The improved fits lead to an empirically derived wavelength-dependent correction to the scattering properties of the main observable cloud deck at 2-3 bars that is very similar to the correction determined for Uranus' lower cloud using the same line dataset by Irwin et al. (Irwin, P.G.J., de Bergh, C., Courtin, R., Bézard, B., Teanby, N.A., Davis, G.R., Fletcher, L.N., Orton, G.S., Calcutt, S.B., Tice, D., Hurley, J. [2012]. Icarus 220, 369-382). By varying the abundance of CH3D in our simulations, analysis of the Gemini/NIFS observations leads to a new determination of the CH3D/CH4 ratio for Neptune of 3.0-0.9+1.0×10-4, which is smaller than previous determinations, but is identical (to within error) with the CH3D/CH4 ratio of 2.9-0.5+0.9×10-4 derived by a similar analysis of Gemini/NIFS observations of Uranus made in the same year. Thus it appears that the atmospheres of Uranus and Neptune have an almost identical D/H ratio, which suggests that the icy planetisimals forming these planets came from the same source reservoir, or a reservoir that was well-mixed at the locations of ice giant formation, assuming complete mixing between the atmosphere and interior of both these planets. VLT/CRIRES observations of Neptune have also been analysed with the WKMC-80K methane line database, yielding very good fits, with little evidence for missing absorption features. The CRIRES spectra indicate that the mole fraction of CO at the 2-3 bar level must be

  15. Mapping of molecular gas inflow towards the Seyfert nucleus of NGC4051 using Gemini NIFS

    NASA Astrophysics Data System (ADS)

    Riffel, Rogemar A.; Storchi-Bergmann, Thaisa; Winge, Cláudia; McGregor, Peter J.; Beck, Tracy; Schmitt, Henrique

    2008-04-01

    We present 2D stellar and gaseous kinematics of the inner ~130×180 pc2 of the Narrow-Line Seyfert 1 galaxy NGC4051 at a sampling of 4.5pc, from near-infrared K-band spectroscopic observations obtained with the Gemini's Near-infrared Integral Field Spectrograph (NIFS) operating with the ALTAIR adaptive optics module. We have used the CO absorption band heads around 2.3μm to obtain the stellar kinematics which show the turnover of the rotation curve at only ~55pc from the nucleus, revealing a highly concentrated gravitational potential. The stellar velocity dispersion of the bulge is ~60kms-1 - implying on a nuclear black hole mass of ~106Msolar - within which patches of lower velocity dispersion suggest the presence of regions of more recent star formation. From measurements of the emission-line profiles we have constructed 2D maps for the flux distributions, line ratios, radial velocities and gas velocity dispersions for the H2, HII and [CaVIII] emitting gas. Each emission-line samples a distinct kinematics. The Brγ emission-line shows no rotation as well as no blueshifts or redshifts in excess of 30kms-1, and is thus not restricted to the galaxy plane. The [CaVIII] coronal region is compact but resolved, extending over the inner 75pc. It shows the highest blueshifts - of up to -250kms-1, and the highest velocity dispersions, interpreted as due to outflows from the active nucleus, supporting an origin close to the nucleus. Subtraction of the stellar velocity field from the gaseous velocity field has allowed us to isolate non-circular motions observed in the H2 emitting gas. The most conspicuous kinematic structures are two nuclear spiral arms - one observed in blueshift in the far side of the galaxy (to the north-east), and the other observed in redshift in the near side of the galaxy (to the south-west). We interpret these structures as inflows towards the nucleus, a result similar to those of previous studies in which we have found streaming motions along

  16. A single-component photo-responsive fluid based on a gemini surfactant with an azobenzene spacer.

    PubMed

    Song, Binglei; Hu, Yufang; Zhao, Jianxi

    2009-05-15

    A new gemini surfactant with an azobenzene group incorporated in the spacer has been synthesized. In water, this new compound forms a photo-responsive fluid, and the properties have been characterized by rheology and freeze-fracture electron microscopy (FF-TEM). UV/Vis irradiation causes a reversible change in zero shear viscosity of about 5 orders of magnitude. The different rheological properties correspond to different aggregation states in solution. A densely entangled network and small discrete micelles are respectively responsible for the high viscosity and the low viscosity state, as revealed by FF-TEM. The simplicity and high photo-efficiency of this single-component system act as a foundation for designing novel stimuli-responsive materials.

  17. Observational constraints on the formation and evolution of the Milky Way nuclear star cluster with Keck and Gemini

    NASA Astrophysics Data System (ADS)

    Do, Tuan; Ghez, Andrea; Morris, Mark; Lu, Jessica; Chappell, Samantha; Feldmeier-Krause, Anja; Kerzendorf, Wolfgang; Martinez, Gregory David; Murray, Norm; Winsor, Nathan

    2017-01-01

    We summarize work on the central parsec of the Galactic center based on imaging and spectroscopic observations at the Keck and Gemini telescopes. These observations include stellar positions in two dimension and the velocity in three dimensions. Spectroscopic observations also enables measurements of the physical properties of individual stars, such as the spectral type and in some cases the effective temperature, metallicity, and surface gravity. These observations show a complex stellar population with a young (4-6 Myr) compact star cluster in the central 0.5 pc embedded in in an older and much more massive nuclear star cluster. Surprisingly, the old late-type giants do not show a cusp profile as long been expected from theoretical work. The majority of the stars have higher than solar metallicity, with only about 6% of the stars having [M/Fe] < -0.5, which is consistent with an origin from the MW disk.

  18. Gemini alkyldeoxy-D-glucitolammonium salts as modern surfactants and microbiocides: synthesis, antimicrobial and surface activity, biodegradation.

    PubMed

    Brycki, Bogumił; Szulc, Adrianna

    2014-01-01

    Dimeric quaternary alkylammonium salts possess a favourable surface and antimicrobial activity. In this paper we describe synthesis, spectroscopic analysis, surface and antimicrobial activity as well as biodegradability of polymethylene-α,ω-bis(N,N-dialkyl-N-deoxy-D-glucitolammonium iodides), a new group of dimeric quaternary ammonium salts. This new group of gemini surfactants can be produced from chemicals which come from renewable sources. The structure of products has been determined by the FTIR and (1)H and (13)C NMR spectroscopy. The biodegradability, surface activity and antimicrobial efficacy against Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus niger and Penicillium chrysogenum were determined. The influence of the number of alkyl chains and their lengths on surface and antimicrobial properties has been shown. In general, dimeric quaternary alkyldeoxy-D-glucitolammonium salts with long alkyl substituents show favourable surface properties and an excellent antimicrobial activity.

  19. Astrometric Confirmation and Preliminary Orbital Parameters of the Young Exoplanet 51 Eridani b with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Nielsen, Eric Ludwig; Blunt, Sarah; De Rosa, Robert; Konopacky, Quinn; Graham, James R.; Macintosh, Bruce; Marchis, Franck; Wang, Jason; Pueyo, Laurent; Rameau, Julien; Marois, Christian

    2015-12-01

    The Gemini Planet Imager Exoplanet Survey discovered the young, 2 Jupiter mass planet 51 Eri b based on observations conducted in December 2014 and January 2015. It is the lowest mass extrasolar planet ever detected by direct imaging and shows strong methane absorption, and is at a projected separation of just 13 AU from its host star. We present new astrometry from late 2015 that confirms 51 Eri b is a bound planet and not an interloping brown dwarf. Orbital motion is detected despite monitoring the system for less than a year. We have implemented a computationally efficient Monte Carlo technique for fitting a range of possible orbital motion based on astrometry covering a small fraction of the period and producing distributions of orbital parameters consistent with the measurements. We apply this technique to the astrometry of 51 Eri b and present preliminary orbital parameter distributions of this intriguing planet.

  20. Electrostatic Interactions Govern “Odd/Even” Effects in Water-Induced Gemini Surfactant Self-Assembly

    SciTech Connect

    Mantha, Sriteja; McDaniel, Jesse G.; Perroni, Dominic V.; Mahanthappa, Mahesh K.; Yethiraj, Arun

    2016-12-27

    Gemini surfactants comprise two single-tailed surfactants connected by a linker at or near the hydrophilic headgroup. They display a variety of water concentration-dependent lyotropic liquid crystal (LLC) morphologies that are sensitive to surfactant molecular structure, and na- ture of the headgroups and counterions. Recently, an interesting dependence of the aqueous phase behavior on the length of the linker has been discovered; odd-numbered linker length surfactants exhibit characteristically different phase diagrams than even-numbered linker sur- factants. In this work, we investigate this “odd/even effect” using computer simulations, focusing on experimentally studied gemini dicarboxylates with Na+ counterions, 7 non-terminal carbon atoms in the tails, and either 3, 4, 5, or 6 carbon atoms in the linker (denoted Na-73, Na-74, Na-75, and Na-76 respectively). We find that the relative electrostatic repulsion be- tween headgroups in the different morphologies is correlated with qualitative features of the experimental phase diagrams, predicting destabilization of hexagonal phases as the cylinders pack close together at low water content. Significant differences in the relative headgroup ori- entations of Na-74 and Na-76 compared to Na-73 and Na-75 surfactants lead to differences in linker-linker packing, and long-range headgroup/headgroup electrostatic repulsion, which affects the delicate electrostatic balance between hexagonal and gyroid phases. Finally, much of the fundamental insight presented in this work is enabled by the ability to computationally construct and analyze metastable phases that are not observable in experiments.

  1. Inhibition of the Transition of Ductal Carcinoma In Situ to Invasive Ductal Carcinoma by a Gemini Vitamin D Analog

    PubMed Central

    Wahler, Joseph; So, Jae Young; Kim, Yeoun Chan; Liu, Fang; Maehr, Hubert; Uskokovic, Milan; Suh, Nanjoo

    2014-01-01

    Ductal carcinoma in situ (DCIS) is a non-malignant lesion of the breast with the potential to progress to invasive ductal carcinoma (IDC). The disappearance and breakdown of the myoepithelial cell layer and basement membrane in DCIS have been identified as major events in the development of breast cancer. The MCF10DCIS.com cell line is a well-established model which recapitulates the progression of breast cancer from DCIS to IDC. We have previously reported that a novel Gemini vitamin D analog, 1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124) is a potent inhibitor of the growth of MCF10DCIS.com xenografted tumors without hypercalcemic toxicity. In the present study, we utilized the MCF10DCIS.com in vivo model to assess the effects of BXL0124 on breast cancer progression from weeks 1 to 4. Upon DCIS progression to IDC from weeks 3 to 4, tumors lost the myoepithelial cell layer and basement membrane as shown by immunofluorescence staining with smooth muscle actin (SMA) and laminin 5, respectively. Administration of BXL0124 maintained the critical myoepithelial cell layer as well as basement membrane, and animals treated with BXL0124 showed a 43% reduction in tumor volume by week 4. BXL0124 treatment decreased cell proliferation and maintained vitamin D receptor (VDR) levels in tumors. In addition, the BXL0124 treatment reduced the mRNA levels of matrix metalloproteinases (MMPs) starting at week 3, contributing to the inhibition of invasive transition. Our results suggest that the maintenance of DCIS plays a significant role in the cancer preventive action of the Gemini vitamin D BXL0124 during the progression of breast lesions. PMID:24691501

  2. SPT-GMOS: A Gemini/GMOS-South Spectroscopic survey of galaxy clusters in the SPT-SZ survey

    DOE PAGES

    Bayliss, M. B.; Ruel, J.; Stubbs, C. W.; ...

    2016-11-01

    Here, we present the results of SPT-GMOS, a spectroscopic survey with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South. The targets of SPT-GMOS are galaxy clusters identified in the SPT-SZ survey, a millimeter-wave survey of 2500 deg2 of the southern sky using the South Pole Telescope (SPT). Multi-object spectroscopic observations of 62 SPT-selected galaxy clusters were performed between 2011 January and 2015 December, yielding spectra with radial velocity measurements for 2595 sources. We identify 2243 of these sources as galaxies, and 352 as stars. Of the galaxies, we identify 1579 as members of SPT-SZ galaxy clusters. The primary goal ofmore » these observations was to obtain spectra of cluster member galaxies to estimate cluster redshifts and velocity dispersions. We describe the full spectroscopic data set and resulting data products, including galaxy redshifts, cluster redshifts, and velocity dispersions, and measurements of several well-known spectral indices for each galaxy: the equivalent width, W, of [O II] λλ3727, 3729 and H-δ, and the 4000 Å break strength, D4000. We use the spectral indices to classify galaxies by spectral type (i.e., passive, post-starburst, star-forming), and we match the spectra against photometric catalogs to characterize spectroscopically observed cluster members as a function of brightness (relative to m*). Lastly, we report several new measurements of redshifts for ten bright, strongly lensed background galaxies in the cores of eight galaxy clusters. Combining the SPT-GMOS data set with previous spectroscopic follow-up of SPT-SZ galaxy clusters results in spectroscopic measurements for >100 clusters, or ~20% of the full SPT-SZ sample.« less

  3. SPT-GMOS: A Gemini/GMOS-South Spectroscopic survey of galaxy clusters in the SPT-SZ survey

    SciTech Connect

    Bayliss, M. B.; Ruel, J.; Stubbs, C. W.; Allen, S. W.; Applegate, D. E.; Ashby, M. L. N.; Bautz, M.; Benson, B. A.; Bleem, L. E.; Bocquet, S.; Carlstrom, J. E.; Chang, C. L.

    2016-11-01

    Here, we present the results of SPT-GMOS, a spectroscopic survey with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South. The targets of SPT-GMOS are galaxy clusters identified in the SPT-SZ survey, a millimeter-wave survey of 2500 deg2 of the southern sky using the South Pole Telescope (SPT). Multi-object spectroscopic observations of 62 SPT-selected galaxy clusters were performed between 2011 January and 2015 December, yielding spectra with radial velocity measurements for 2595 sources. We identify 2243 of these sources as galaxies, and 352 as stars. Of the galaxies, we identify 1579 as members of SPT-SZ galaxy clusters. The primary goal of these observations was to obtain spectra of cluster member galaxies to estimate cluster redshifts and velocity dispersions. We describe the full spectroscopic data set and resulting data products, including galaxy redshifts, cluster redshifts, and velocity dispersions, and measurements of several well-known spectral indices for each galaxy: the equivalent width, W, of [O II] λλ3727, 3729 and H-δ, and the 4000 Å break strength, D4000. We use the spectral indices to classify galaxies by spectral type (i.e., passive, post-starburst, star-forming), and we match the spectra against photometric catalogs to characterize spectroscopically observed cluster members as a function of brightness (relative to m*). Lastly, we report several new measurements of redshifts for ten bright, strongly lensed background galaxies in the cores of eight galaxy clusters. Combining the SPT-GMOS data set with previous spectroscopic follow-up of SPT-SZ galaxy clusters results in spectroscopic measurements for >100 clusters, or ~20% of the full SPT-SZ sample.

  4. Gemini South Multi-Object Spectrograph (GMOS-S) detector Video boards upgrade: improved performance for the Hamamatsu CCDs.

    NASA Astrophysics Data System (ADS)

    Gimeno, German; Boucher, Luc; Chiboucas, Kristin; Hibon, Pascale; Lazo, Manuel; Murowinski, Richard; Rippa, Matthew; Rogers, Rolando; Rojas, Roberto; Roth, Katherine; White, John

    2016-01-01

    GMOS-S was upgraded with new Hamamatsu CCDs on June 2014, featuring an improved red sensitivity with respect to the previous detectors and significantly less fringing. Early after the commissioning, an issue was identified when observing in any of the binned readout modes, namely that saturated pixels produced a decrease of counts with respect to the bias level in neighboring pixels. This effect, also known as 'banding', spanned the entire width of the amplifier, and while it did not destroy information, it rendered data reduction very cumbersome. Making matters worse, due to the saturation of a bad column on amplifier number 5 (on CCD2, near the middle of the focal plane), it ended up affecting the entire amplifier for almost all exposures longer than a minute. A team of Gemini instrument scientists and engineers investigated the issue and identified the root cause of the problem as originated in the ARC controller video boards. After significant lab testing, it was verified that a newly available revision of the video boards would solve the problem, though modification of the software was required in order to be compatible with them. This work was performed during the last semester of 2014 and the first semester of 2015. The new video boards were installed and commissioned during August 2015. As of September 1st, the new boards are fully installed and integrated, and the 'banding' effect has been completely eliminated. A short period of time was devoted to the recharacterization of the detector system and the new values for the gains, read noise and full well capacity have been derived. As an added benefit, the full well was increased by ~ 10 percent with respect to the previous value. The GMOS-S new detectors are now operating normally in the Gemini observing queue, and performing at full capacity.

  5. SPT-GMOS: A Gemini/GMOS-South Spectroscopic Survey of Galaxy Clusters in the SPT-SZ Survey

    NASA Astrophysics Data System (ADS)

    Bayliss, M. B.; Ruel, J.; Stubbs, C. W.; Allen, S. W.; Applegate, D. E.; Ashby, M. L. N.; Bautz, M.; Benson, B. A.; Bleem, L. E.; Bocquet, S.; Brodwin, M.; Capasso, R.; Carlstrom, J. E.; Chang, C. L.; Chiu, I.; Cho, H.-M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dietrich, J. P.; Dobbs, M. A.; Doucouliagos, A. N.; Foley, R. J.; Forman, W. R.; Garmire, G. P.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Gupta, N.; Halverson, N. W.; Hlavacek-Larrondo, J.; Hoekstra, H.; Holder, G. P.; Holzapfel, W. L.; Hou, Z.; Hrubes, J. D.; Huang, N.; Jones, C.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; von der Linden, A.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L. M.; Mohr, J. J.; Murray, S. S.; Padin, S.; Pryke, C.; Rapetti, D.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Schrabback, T.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K. T.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zenteno, A.

    2016-11-01

    We present the results of SPT-GMOS, a spectroscopic survey with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South. The targets of SPT-GMOS are galaxy clusters identified in the SPT-SZ survey, a millimeter-wave survey of 2500 deg2 of the southern sky using the South Pole Telescope (SPT). Multi-object spectroscopic observations of 62 SPT-selected galaxy clusters were performed between 2011 January and 2015 December, yielding spectra with radial velocity measurements for 2595 sources. We identify 2243 of these sources as galaxies, and 352 as stars. Of the galaxies, we identify 1579 as members of SPT-SZ galaxy clusters. The primary goal of these observations was to obtain spectra of cluster member galaxies to estimate cluster redshifts and velocity dispersions. We describe the full spectroscopic data set and resulting data products, including galaxy redshifts, cluster redshifts, and velocity dispersions, and measurements of several well-known spectral indices for each galaxy: the equivalent width, W, of [O ii] λλ3727, 3729 and H-δ, and the 4000 Å break strength, D4000. We use the spectral indices to classify galaxies by spectral type (i.e., passive, post-starburst, star-forming), and we match the spectra against photometric catalogs to characterize spectroscopically observed cluster members as a function of brightness (relative to m ⋆). Finally, we report several new measurements of redshifts for ten bright, strongly lensed background galaxies in the cores of eight galaxy clusters. Combining the SPT-GMOS data set with previous spectroscopic follow-up of SPT-SZ galaxy clusters results in spectroscopic measurements for >100 clusters, or ∼20% of the full SPT-SZ sample.

  6. Electrostatic Interactions Govern “Odd/Even” Effects in Water-Induced Gemini Surfactant Self-Assembly

    DOE PAGES

    Mantha, Sriteja; McDaniel, Jesse G.; Perroni, Dominic V.; ...

    2016-12-27

    Gemini surfactants comprise two single-tailed surfactants connected by a linker at or near the hydrophilic headgroup. They display a variety of water concentration-dependent lyotropic liquid crystal (LLC) morphologies that are sensitive to surfactant molecular structure, and na- ture of the headgroups and counterions. Recently, an interesting dependence of the aqueous phase behavior on the length of the linker has been discovered; odd-numbered linker length surfactants exhibit characteristically different phase diagrams than even-numbered linker sur- factants. In this work, we investigate this “odd/even effect” using computer simulations, focusing on experimentally studied gemini dicarboxylates with Na+ counterions, 7 non-terminal carbon atoms inmore » the tails, and either 3, 4, 5, or 6 carbon atoms in the linker (denoted Na-73, Na-74, Na-75, and Na-76 respectively). We find that the relative electrostatic repulsion be- tween headgroups in the different morphologies is correlated with qualitative features of the experimental phase diagrams, predicting destabilization of hexagonal phases as the cylinders pack close together at low water content. Significant differences in the relative headgroup ori- entations of Na-74 and Na-76 compared to Na-73 and Na-75 surfactants lead to differences in linker-linker packing, and long-range headgroup/headgroup electrostatic repulsion, which affects the delicate electrostatic balance between hexagonal and gyroid phases. Finally, much of the fundamental insight presented in this work is enabled by the ability to computationally construct and analyze metastable phases that are not observable in experiments.« less

  7. Review of the Lightning Strike Incident at Launch Complex 37 on July 27, 1967, and Comparison to a Gemini Lightning Strike

    NASA Technical Reports Server (NTRS)

    Llewellyn, J. A.

    1967-01-01

    The Launch Complex 37 lightning strike of July 27, 1967, was reviewed and compared to a similar incident on the Gemini Program. Available data indicate little likelihood of damaging currents having been present in SA-204 Launch Vehicle or the ground equipment during the July 27th incident. Based on the results of subsystem and system testing after the strike, anticipated results of future testing, the six months elapsed time between the strike-and launch, and the fact that much of the critical airborne electrical/electronic equipment has been removed since the strike for other reasons, no new actions are considered necessary at this time in the Gemini case, significant failures occurred in both airborne and ground circuits. Due to the resultant semi, condlictor uncertainty, and the relatively' short time prior to planned launch, all critical airborne components containing semiconduetors were replaced, and a sophisticated data comparison task was implemented.

  8. OBSERVATIONS OF BINARY STARS WITH THE DIFFERENTIAL SPECKLE SURVEY INSTRUMENT. IV. OBSERVATIONS OF KEPLER, CoRoT, AND HIPPARCOS STARS FROM THE GEMINI NORTH TELESCOPE

    SciTech Connect

    Horch, Elliott P.; Howell, Steve B.; Everett, Mark E.; Ciardi, David R. E-mail: steve.b.howell@nasa.gov E-mail: ciardi@ipac.caltech.edu

    2012-12-01

    We present the results of 71 speckle observations of binary and unresolved stars, most of which were observed with the DSSI speckle camera at the Gemini North Telescope in 2012 July. The main purpose of the run was to obtain diffraction-limited images of high-priority targets for the Kepler and CoRoT missions, but in addition, we observed a number of close binary stars where the resolution limit of Gemini was used to better determine orbital parameters and/or confirm results obtained at or below the diffraction limit of smaller telescopes. Five new binaries and one triple system were discovered, and first orbits are calculated for other two systems. Several systems are discussed in detail.

  9. Characterization and testing of FLAMINGOS-2: the Gemini facility near-infrared multi-object spectrometer and wide-field imager

    NASA Astrophysics Data System (ADS)

    Raines, Steven N.; Eikenberry, Stephen S.; Bandyopadhyay, Reba M.; Julian, Jeffrey A.; Hanna, Kevin T.; Warner, Craig D.; Julian, Roger E.; Bennett, J. Greg; DeWitt, Curtis N.; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael D.; Murphey, Charles

    2008-07-01

    FLAMINGOS-2 is a near-infrared wide-field imager and fully cryogenic multi-object spectrometer for Gemini Observatory being built by the University of Florida. FLAMINGOS-2 can simultaneously carry 9 custom cryogenic multi-object slit masks exchangeable without thermally cycling the entire instrument. Three selectable grisms provide resolving powers which are ~1300 to ~3000 over the entire spectrograph bandpass of 0.9-2.5 microns. We present and discuss characterization data for FLAMINGOS-2 including imaging throughput, image quality, spectral performance, and noise performance. After a lengthy integration process, we expect that FLAMINGOS-2 will be in the midst of commissioning at Gemini South by the fall of 2008.

  10. Cationic gemini surfactant as a dual linker for a cholic acid-modified polysaccharide in aqueous solution: thermodynamics of interaction and phase behavior.

    PubMed

    Bai, Guangyue; Wu, Hui; Lou, Pengxiao; Wang, Yujie; Nichifor, Marieta; Zhuo, Kelei; Wang, Jianji; Bastos, Margarida

    2017-01-04

    Understanding the thermodynamics of formation of biocompatible aggregates is a key factor in the bottom up approach to the development of novel types of drug carriers and their structural tuning using small amphiphilic molecules. We chose an anionic amphiphilic and biocompatible polymer that consists of a dextran and grafted cholic acid pendants, randomly distributed along the dextran backbone, with a degree of substitution (DS) of 15 mol% (designated Dex-15CACOONa). The thermodynamics of interaction and phase behavior of mixtures of this polyelectrolyte and a cationic gemini surfactant hexanediyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C6C12Br2) or its monomer surfactant dodecyltrimethylammonium bromide (DTAB) in aqueous solution were characterized by isothermal titration calorimetry (ITC) and turbidity, together with cryogenic transmission electron microscopy (Cryo-TEM). The various critical concentrations and the enthalpy changes of the corresponding phase transitions for the oppositely charged system were obtained from the plots of the observed enthalpy change (ΔHobs) and turbidity measurements as a function of gemini concentration. The morphologies of the aggregates in various phases were observed by Cryo-TEM. Altogether these results suggest the critical role of gemini as a dual linker. At the concentrations where the crosslink between the pendant aggregates happens, the free gemini concentration is proximately zero and the aggregate retains its negative charge. The analysis of various factors involved in the interaction allowed a rationalization of the driving forces for mixed aggregate formation, which will contribute to a subsequent rational design of drug delivery systems based on this polymer/surfactant system.

  11. Conformational alterations induced by novel green 16-E2-16 gemini surfactant in xanthine oxidase: Biophysical insights from tensiometry, spectroscopy, microscopy and molecular modeling.

    PubMed

    Akram, Mohd; Bhat, Imtiyaz Ahmad; Bhat, Waseem Feeroze; Kabir-ud-Din

    2015-01-01

    Herein we report the interaction of a biodegradable gemini surfactant, ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride (16-E2-16) with bovine milk xanthine oxidase (XO), employing tensiometry, fluorescence spectroscopy, UV spectroscopy, far-UV circular dichroism spectroscopy (CD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and computational molecular modeling. Surface tension results depict substantial changes in the micellar as well as interfacial parameters (CMC, ΠCMC, γCMC, Γmax, Amin, ΔGmic° and ΔGads°) of 16-E2-16 gemini surfactant upon XO combination, deciphering the interaction of XO with the gemini surfactant. Fluorescence measurements reveal that 16-E2-16 gemini surfactant causes quenching in the xanthine oxidase (XO) fluorescence spectra via static procedure and the values of various evaluated binding parameters (KSV, Kb, kq, ΔGb° and n) describe that 16-E2-16 effectively binds to XO. Three dimensional fluorescence, 8-anilino-1-naphthalene sulfonic acid (ANS) binding, F1F3 ratio, UV, CD, FTIR, SEM and TEM results delineate changes in the secondary structure of xanthine oxidase. Molecular docking results provide complement to the steady-state fluorescence findings and support the view that quenching occurs due to non-polar environment experienced by aromatic residues of the enzyme. The results of this study can help scientists to tune the conformation of an enzyme (XO) with biocompatible amphiphilic microstructures, which will help to unfold further understanding in the treatment modes of various diseases like gout, hyperuricemia, liver and brain necrosis.

  12. Facile controlled synthesis of micro/nanostructure MCrO 4 (M = Ba, Pb) by using Gemini surfactant C 12-PEG-C 12 as a soft template

    NASA Astrophysics Data System (ADS)

    Chang, Wengui; Shen, Yuhua; Xie, Anjian; Liu, Xue

    2010-04-01

    Gemini surfactants, double sodium α-sulfonic polyethylene glycol laurate (abbreviated C 12-PEG-C 12), were prepared and applied as soft templates in the controlled synthesis of BaCrO 4 and PbCrO 4 micro/nanocrystals. The template effects were investigated by adjusting the length of the spacer, using PEG400 and PEG4000, of the Gemini surfactant. The results indicated that the size and morphology of BaCrO 4 and PbCrO 4 micro/nanocrystals varied with the change in spacer length of C 12-PEG-C 12, suggesting that the different lengths of the polyethylene glycol group spacers in the Gemini surfactants played a key role in determining the size and shape of the MCrO 4 micro/nanoparticles. The dynamic process of the formation of the novel morphology BaCrO 4 crystals showed that the morphology grew from a round-bar polyhedron, to regular polyhedron, to approximate octahedron to a uniform pistachio nut shape. The growth mechanism of the BaCrO 4 micro/nanocrystals was explained that C 12-PEG-C 12 had a greater interfacial adsorption and would effectively control the shape evolution during the crystal growth, while PbCrO 4 could be explained that the Gemini surfactants can undergo liquid-crystalline phase transitions with long channels providing a soft template effect and derived the nanorods formation. Room temperature fluorescence spectra were studied and these showed that the pistachio-shaped BaCrO 4 microcrystals and PbCrO 4 nanorods possess photoactive luminescence properties with emission peaks at 470 and 549 nm, respectively.

  13. Gemini Frontier Fields: Wide-field Adaptive Optics Ks-band Imaging of the Galaxy Clusters MACS J0416.1-2403 and Abell 2744

    NASA Astrophysics Data System (ADS)

    Schirmer, M.; Carrasco, E. R.; Pessev, P.; Garrel, V.; Winge, C.; Neichel, B.; Vidal, F.

    2015-04-01

    We have observed two of the six Frontier Fields galaxy clusters, MACS J0416.1-2403 and Abell 2744, using the Gemini Multi-Conjugate Adaptive Optics System (GeMS) and the Gemini South Adaptive Optics Imager (GSAOI). With 0.″ 08-0.″ 10 FWHM our data are nearly diffraction-limited over a 100\\prime\\prime × 100\\prime\\prime wide area. GeMS/GSAOI complements the Hubble Space Telescope (HST) redwards of 1.6 μm with twice the angular resolution. We reach a 5σ depth of {{K}s}˜ 25.6 mag (AB) for compact sources. In this paper, we describe the observations, data processing, and initial public data release. We provide fully calibrated, co-added images matching the native GSAOI pixel scale as well as the larger plate scales of the HST release, adding to the legacy value of the Frontier Fields. Our work demonstrates that even for fields at high galactic latitude where natural guide stars are rare, current multi-conjugated adaptive optics technology at 8 m telescopes has opened a new window on the distant universe. Observations of a third Frontier Field, Abell 370, are planned. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). Based on observations made with ESO Telescopes at the La Silla and Paranal Observatories, Chile.

  14. The Gemini/NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars

    NASA Astrophysics Data System (ADS)

    Biller, Beth A.; Liu, Michael C.; Wahhaj, Zahed; Nielsen, Eric L.; Hayward, Thomas L.; Males, Jared R.; Skemer, Andrew; Close, Laird M.; Chun, Mark; Ftaclas, Christ; Clarke, Fraser; Thatte, Niranjan; Shkolnik, Evgenya L.; Reid, I. Neill; Hartung, Markus; Boss, Alan; Lin, Douglas; Alencar, Silvia H. P.; de Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane; Toomey, Douglas

    2013-11-01

    We report results of a direct imaging survey for giant planets around 80 members of the β Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ΔH = 13.9 mag at 1'' in combined CH4 narrowband ADI+SDI mode and median contrasts of ΔH = 15.1 mag at 2'' in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with Near-Infrared Coronagraphic Imager (NICI) all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI Campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 ± 6 M Jup, 16.4 ± 1.0 AU), CD-35 2722B (31 ± 8 M Jup, 67 ± 4 AU), HD 12894B (0.46 ± 0.08 M ⊙, 15.7 ± 1.0 AU), and BD+07 1919C (0.20 ± 0.03 M ⊙, 12.5 ± 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50 AU as well. We restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-50 AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc

  15. Bis-quaternary gemini surfactants as components of nonviral gene delivery systems: a comprehensive study from physicochemical properties to membrane interactions.

    PubMed

    Cardoso, Ana M; Morais, Catarina M; Silva, Sandra G; Marques, Eduardo F; de Lima, Maria C Pedroso; Jurado, Maria Amália S

    2014-10-20

    Gemini surfactants have been successfully used as components of gene delivery systems. In the present work, a family of gemini surfactants, represented by the general structure [CmH2m+1(CH3)2N(+)(CH2)sN(+)(CH3)2CmH2m+1]2Br(-), or simply m-s-m, was used to prepare cationic gene carriers, aiming at their application in transfection studies. An extensive characterization of the gemini surfactant-based complexes, produced with and without the helper lipids cholesterol and DOPE, was carried out in order to correlate their physico-chemical properties with transfection efficiency. The most efficient complexes were those containing helper lipids, which, combining amphiphiles with propensity to form structures with different intrinsic curvatures, displayed a morphologically labile architecture, putatively implicated in the efficient DNA release upon complex interaction with membranes. While complexes lacking helper lipids were translocated directly across the lipid bilayer, complexes containing helper lipids were taken up by cells also by macropinocytosis. This study contributes to shed light on the relationship between important physico-chemical properties of surfactant-based DNA vectors and their efficiency to promote gene transfer, which may represent a step forward to the rational design of gene delivery systems.

  16. Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study

    PubMed Central

    Pietralik, Zuzanna; Kołodziejska, Żaneta; Weiss, Marek; Kozak, Maciej

    2015-01-01

    The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration), they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp) and siRNA (21 bp). The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16). On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain). PMID:26641889

  17. Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study.

    PubMed

    Pietralik, Zuzanna; Kołodziejska, Żaneta; Weiss, Marek; Kozak, Maciej

    2015-01-01

    The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration), they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp) and siRNA (21 bp). The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16). On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain).

  18. Gemini Spectroscopy of Supernovae from the Supernova Legacy Survey: Improving High-Redshift Supernova Selection and Classification

    NASA Astrophysics Data System (ADS)

    Howell, D. A.; Sullivan, M.; Perrett, K.; Bronder, T. J.; Hook, I. M.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Knop, R.; McMahon, R. G.; Perlmutter, S.; Walton, N. A.

    2005-12-01

    We present new techniques for improving the efficiency of supernova (SN) classification at high redshift using 64 candidates observed at Gemini North and South during the first year of the Supernova Legacy Survey (SNLS). The SNLS is an ongoing 5 year project with the goal of measuring the equation of state of dark energy by discovering and following over 700 high-redshift SNe Ia using data from the Canada-France-Hawaii Telescope Legacy Survey. We achieve an improvement in the SN Ia spectroscopic confirmation rate: at Gemini 71% of candidates are now confirmed as SNe Ia, compared to 54% using the methods of previous surveys. This is despite the comparatively high redshift of this sample, in which the median SN Ia redshift is z=0.81 (0.155<=z<=1.01). These improvements were realized because we use the unprecedented color coverage and light curve sampling of the SNLS to predict whether a candidate is a SN Ia and to estimate its redshift, before obtaining a spectrum, using a new technique called the ``SN photo-z.'' In addition, we have improved techniques for galaxy subtraction and SN template χ2 fitting, allowing us to identify candidates even when they are only 15% as bright as the host galaxy. The largest impediment to SN identification is found to be host galaxy contamination of the spectrum-when the SN was at least as bright as the underlying host galaxy the target was identified more than 90% of the time. However, even SNe in bright host galaxies can be easily identified in good seeing conditions. When the image quality was better than 0.55", the candidate was identified 88% of the time. Over the 5 year course of the survey, using the selection techniques presented here, we will be able to add ~170 more confirmed SNe Ia than would be possible using previous methods. APC, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France. DSM/DAPNIA, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France.

  19. Design and synthesis of new type I bicontinuous cubic lyotropic liquid crystal monomers based on the gemini framework for molecular-size separation applications

    NASA Astrophysics Data System (ADS)

    Wiesenauer, Brian R.

    The overall objective of this thesis research was the design and synthesis of new type I bicontinuous cubic (QI) phase-forming, gemini-shaped lyotropic liquid crystal (LLC) monomers for the preparation of nanoporous polymer membrane materials. These new QI-phase LLC monomers were designed to overcome several shortcomings of previously developed QI-phase LLC monomers in the Gin research group that include expensive and difficult synthesis, poor film processibility, and limited blendability with additives. The first method for obtaining this objective was the synthesis of six homologues of a new gemini ammonium LLC monomer, two of which exhibit a QI phase with water. Both of these LLCs form a robust Q I phase such that a gel of these materials can be fully infused into a microporous support membrane and then cross-linked to maintain the LLC phase structure. The resulting QI-phase polymer film showed a uniform pore size of 0.86 nm in water nanofiltration and desalination experiments. This QI monomer platform is less costly and less rigorous to synthesize than previously synthesized phosphonium-based gemini QI LLC monomers. These new LLC monomers also have the ability to blend with the hydrophobic, commercially available cross-linkable elastomer vinyl-EPDM (v-EPDM) to form breathable composite barrier materials. In the appropriate composition, melt-infused gemini ammonium monomer/v-EPDM polymer membranes exhibit extremely high pure water vapor fluxes, and high rejection of toxic industrial chemical vapors. A new cross-linkable gemini LLC monomer based on charged imidazolium units was also developed that forms a QI phase with glycerol. This new LLC monomer can be solution-cast from MeOH and UV-irradiated to form cross-linked thin-film composite QI membranes with slightly larger effective pore size (0.96 nm) than the previous systems. A related goal of this thesis research was to develop methods for systematically tuning the effective pore size of nanoporous QI polymer

  20. POLARIMETRY WITH THE GEMINI PLANET IMAGER: METHODS, PERFORMANCE AT FIRST LIGHT, AND THE CIRCUMSTELLAR RING AROUND HR 4796A

    SciTech Connect

    Perrin, Marshall D.; Duchene, Gaspard; Graham, James R.; Kalas, Paul G.; Millar-Blanchaer, Max; Fitzgerald, Michael P.; Chilcote, Jeffrey; Wiktorowicz, Sloane J.; Dillon, Daren; Gavel, Donald; Macintosh, Bruce; Bauman, Brian; Cardwell, Andrew; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; De Rosa, Robert J.; Doyon, René; Dunn, Jennifer; Erikson, Darren; and others

    2015-02-01

    We present the first results from the polarimetry mode of the Gemini Planet Imager (GPI), which uses a new integral field polarimetry architecture to provide high contrast linear polarimetry with minimal systematic biases between the orthogonal polarizations. We describe the design, data reduction methods, and performance of polarimetry with GPI. Point-spread function (PSF) subtraction via differential polarimetry suppresses unpolarized starlight by a factor of over 100, and provides sensitivity to circumstellar dust reaching the photon noise limit for these observations. In the case of the circumstellar disk around HR 4796A, GPI's advanced adaptive optics system reveals the disk clearly even prior to PSF subtraction. In polarized light, the disk is seen all the way in to its semi-minor axis for the first time. The disk exhibits surprisingly strong asymmetry in polarized intensity, with the west side ≳ 9 times brighter than the east side despite the fact that the east side is slightly brighter in total intensity. Based on a synthesis of the total and polarized intensities, we now believe that the west side is closer to us, contrary to most prior interpretations. Forward scattering by relatively large silicate dust particles leads to the strong polarized intensity on the west side, and the ring must be slightly optically thick in order to explain the lower brightness in total intensity there. These findings suggest that the ring is geometrically narrow and dynamically cold, perhaps shepherded by larger bodies in the same manner as Saturn's F ring.

  1. THE GEMINI NICI PLANET-FINDING CAMPAIGN: DISCOVERY OF A MULTIPLE SYSTEM ORBITING THE YOUNG A STAR HD 1160

    SciTech Connect

    Nielsen, Eric L.; Liu, Michael C.; Wahhaj, Zahed; Bowler, Brendan; Kraus, Adam; Chun, Mark; Ftaclas, Christ; Biller, Beth A.; Hayward, Thomas L.; Shkolnik, Evgenya L.; Tecza, Matthias; Clarke, Fraser; Close, Laird M.; Hartung, Markus; Males, Jared R.; Skemer, Andrew J.; Reid, I. Neill; Alencar, Silvia H. P.; Burrows, Adam; and others

    2012-05-01

    We report the discovery of two low-mass companions to the young A0V star HD 1160 at projected separations of 81 {+-} 5 AU (HD 1160 B) and 533 {+-} 25 AU (HD 1160 C) by the Gemini NICI Planet-Finding Campaign. Very Large Telescope images of the system taken over a decade for the purpose of using HD 1160 A as a photometric calibrator confirm that both companions are physically associated. By comparing the system to members of young moving groups and open clusters with well-established ages, we estimate an age of 50{sup +50}{sub -40} Myr for HD 1160 ABC. While the UVW motion of the system does not match any known moving group, the small magnitude of the space velocity is consistent with youth. Near-IR spectroscopy shows HD 1160 C to be an M3.5 {+-} 0.5 star with an estimated mass of 0.22{sup +0.03}{sub -0.04} M{sub Sun }, while NIR photometry of HD 1160 B suggests a brown dwarf with a mass of 33{sup +12}{sub -9} M{sub Jup}. The very small mass ratio (0.014) between the A and B components of the system is rare for A star binaries, and would represent a planetary-mass companion were HD 1160 A to be slightly less massive than the Sun.

  2. FURTHER EVIDENCE OF THE PLANETARY NATURE OF HD 95086 b FROM GEMINI/NICI H-BAND DATA

    SciTech Connect

    Meshkat, T.; Kenworthy, M.; Bailey, V.; Su, K. Y. L.; Rameau, J.; Chauvin, G.; Lagrange, A.-M.; Boccaletti, A.; Mamajek, E. E.; Currie, T.

    2013-10-01

    We present our analysis of the Gemini/NICI H-band data of HD 95086, following the discovery of the planet HD 95086 b in L'. The H-band data reach a contrast of 12.7 mag relative to the host star at 5σ levels in the location of HD 95086 b, and no point source is found. Our non-detection and H – L' color limit rules out the possibility that the object is a foreground L/T dwarf and that, if it is bound to HD 95086, it is a genuine planetary mass object. We estimate a new pre-main-sequence isochronal age for HD 95086 of 17 ± 4 Myr, which is commensurate with previous mean age estimates for the Lower Cen-Crux subgroup. Adopting an age of 17 Myr, the color limit is inconsistent with the COND model, marginally consistent with the BT-SETTL model, and consistent with the DUSTY model.

  3. Two-dimensional growth of crystalline nanofiber fabricated from Gemini-type amphiphilic diamide derivative inducing the thixotropic property.

    PubMed

    Iizuka, Manami; Nakagawa, Yuto; Ohmura, Kyohei; Satou, Eiichi; Fujimori, Atsuhiro

    2017-03-04

    The formation of a nanofiber morphology at the mesoscopic scale and the molecular-level packing of a gemini-type amphiphilic diamide derivative with two hydrocarbons were investigated from two perspectives. First, it was confirmed that a diamide derivative with two hydrocarbons forms crystalline nanofibers even in a monomolecular layer. The height, thickness, and lattice spacing of the two-dimensional orthorhombic system of this crystalline nanofiber in the monolayer of a diamide derivative with two hydrocarbons are 5, 30, and 0.4nm, respectively. Next, it was determined that the fibrous growth of the diamide derivative with two hydrocarbons, which contributes to the thixotropic ability, can be achieved by the addition of a quaternary ammonium cation with long chains, modified with montmorillonite. Here, the interlayer spacing was about 3.8nm for the organo-modified montmorillonite and was consistent with the layer spacing of the diamide derivative having two hydrocarbons. The surface pressure-area isotherms of the mixed monolayers suggest that there is miscibility between these materials. From "the affinity due to the van der Waals interaction between the terminal groups of the alkyl chains" and the "similarity of layer spacing," epitaxial growth is expected.

  4. Polarimetry with the Gemini Planet Imager: methods, performance at first light, and the circumstellar ring around HR 4796A

    SciTech Connect

    Perrin, Marshall D.; Duchene, Gaspard; Millar-Blanchaer, Max; Fitzgerald, Michael P.; Graham, James R.; Wiktorowicz, Sloane J.; Kalas, Paul G.; Macintosh, Bruce; Bauman, Brian; Cardwell, Andrew; Chilcote, Jeffrey; De Rosa, Robert J.; Dillon, Daren; Doyon, René; Dunn, Jennifer; Erikson, Darren; Gavel, Donald; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Ingraham, Patrick; Kerley, Daniel; Konapacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marois, Christian; Mittal, Tushar; Morzinski, Katie M.; Oppenheimer, B. R.; Palmer, David W.; Patience, Jennifer; Poyneer, Lisa; Pueyo, Laurent; Rantakyrö, Fredrik T.; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Soummer, Rémi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wang, Jason J.; Wolff, Schuyler G.

    2015-01-28

    We present the first results from the polarimetry mode of the Gemini Planet Imager (GPI), which uses a new integral field polarimetry architecture to provide high contrast linear polarimetry with minimal systematic biases between the orthogonal polarizations. We describe the design, data reduction methods, and performance of polarimetry with GPI. Point spread function subtraction via di erential polarimetry suppresses unpolarized starlight by a factor of over 100, and provides sensitivity to circumstellar dust reaching the photon noise limit for these observations. In the case of the circumstellar disk around HR 4796A, GPI's advanced adaptive optics system reveals the disk clearly even prior to PSF subtraction. In polarized light, the disk is seen all the way in to its semi-minor axis for the first time. The disk exhibits surprisingly strong asymmetry in polarized intensity, with the west side ≳ 9 times brighter than the east side despite the fact that the east side is slightly brighter in total intensity. Based on a synthesis of the total and polarized intensities, we now believe that the west side is closer to us, contrary to most prior interpretations. Forward scattering by relatively large silicate dust particles leads to the strong polarized intensity on the west side, and the ring must be slightly optically thick in order to explain the lower brightness in total intensity there. These findings suggest that the ring is geometrically narrow and dynamically cold, perhaps shepherded by larger bodies in the same manner as Saturn's F ring.

  5. Polarimetry with the Gemini Planet Imager. Methods, performance at first light, and the circumstellar ring around HR 4796A

    SciTech Connect

    Perrin, Marshall D.; Duchene, Gaspard; Millar-Blanchaer, Max; Fitzgerald, Michael P.; Graham, James R.; Wiktorowicz, Sloane J.; Kalas, Paul G.; Macintosh, Bruce; Bauman, Brian; Cardwell, Andrew; Chilcote, Jeffrey; De Rosa, Robert J.; Dillon, Daren; Doyon, René; Dunn, Jennifer; Erikson, Darren; Gavel, Donald; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Ingraham, Patrick; Kerley, Daniel; Konapacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marois, Christian; Mittal, Tushar; Morzinski, Katie M.; Oppenheimer, B. R.; Palmer, David W.; Patience, Jennifer; Poyneer, Lisa; Pueyo, Laurent; Rantakyrö, Fredrik T.; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Soummer, Rémi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wang, Jason J.; Wolff, Schuyler G.

    2015-01-28

    We report he first results from the polarimetry mode of the Gemini Planet Imager (GPI), which uses a new integral field polarimetry architecture to provide high contrast linear polarimetry with minimal systematic biases between the orthogonal polarizations. We describe the design, data reduction methods, and performance of polarimetry with GPI. Point-spread function (PSF) subtraction via differential polarimetry suppresses unpolarized starlight by a factor of over 100, and provides sensitivity to circumstellar dust reaching the photon noise limit for these observations. In the case of the circumstellar disk around HR 4796A, GPI’s advanced adaptive optics system reveals the disk clearly even prior to PSF subtraction. In polarized light, the disk is seen all the way in to its semi-minor axis for the first time. The disk exhibits surprisingly strong asymmetry in polarized intensity, with the west side ≳9 times brighter than the east side despite the fact that the east side is slightly brighter in total intensity. Based on a synthesis of the total and polarized intensities, we now believe that the west side is closer to us, contrary to most prior interpretations. Forward scattering by relatively large silicate dust particles leads to the strong polarized intensity on the west side, and the ring must be slightly optically thick in order to explain the lower brightness in total intensity there. In conclusion, these findings suggest that the ring is geometrically narrow and dynamically cold, perhaps shepherded by larger bodies in the same manner as Saturn’s F ring.

  6. Organosilane with Gemini-Type Structure as the Mesoporogen for the Synthesis of the Hierarchical Porous ZSM-5 Zeolite.

    PubMed

    Zhu, Haibo; Abou-Hamad, Edy; Chen, Yin; Saih, Youssef; Liu, Weibing; Samal, Akshaya Kumar; Basset, Jean-Marie

    2016-03-01

    A new kind of organosilane (1,6-bis(diethyl(3-trimethoxysilylpropyl)ammonium) hexane bromide) with a gemini-type structure was prepared and used as a mesoporogen for the synthesis of hierarchical porous ZSM-5 zeolite. There are two quaternary ammonium centers along with double-hydrolyzable -RSi(OMe)3 fragments in the organosilane, which results in a strong interaction between this mesoporogen and silica-alumina gel. The organosilane can be easily incorporated into the ZSM-5 zeolite structure during the crystallization process, and it was finally removed by calcination, leading to secondary pores in ZSM-5. The synthesized ZSM-5 has been systematically studied by XRD, nitrogen adsorption, SEM, TEM, TG, and solid-state one-dimensional (1D) and two-dimensional (2D) NMR, which reveal information on its detailed structure. It has a hierarchical porosity system, which combines the intrinsic micropores coming from the crystalline structure and irregular mesopores created by the organosilane template. Moreover, the mesoposity including pore size and volume within ZSM-5 can be systematically tuned by changing the organosilane/TEOS ratio, which confirms that this organosilane has high flexibility of use as a template for the synthesis of hierarchical porous zeolite.

  7. Dynamical Mass Measurement of the Young Spectroscopic Binary V343 Normae AaAb Resolved With the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Nielsen, Eric L.; De Rosa, Robert J.; Wang, Jason; Rameau, Julien; Song, Inseok; Graham, James R.; Macintosh, Bruce; Ammons, Mark; Bailey, Vanessa P.; Barman, Travis S.; Bulger, Joanna; Chilcote, Jeffrey K.; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Fitzgerald, Michael P.; Follette, Katherine B.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn M.; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Oppenheimer, Rebecca; Palmer, David W.; Patience, Jenny; Perrin, Marshall D.; Poyneer, Lisa A.; Pueyo, Laurent; Rajan, Abhijith; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2016-12-01

    We present new spatially resolved astrometry and photometry from the Gemini Planet Imager of the inner binary of the young multiple star system V343 Normae, which is a member of the β Pictoris (β Pic) moving group. V343 Normae comprises a K0 and mid-M star in a ˜4.5 year orbit (AaAb) and a wide 10″ M5 companion (B). By combining these data with archival astrometry and radial velocities we fit the orbit and measure individual masses for both components of {M}{Aa}=1.10+/- 0.10 {M}⊙ and {M}{Ab}=0.290+/- 0.018 {M}⊙ . Comparing to theoretical isochrones, we find good agreement for the measured masses and JHK band magnitudes of the two components consistent with the age of the β Pic moving group. We derive a model-dependent age for the β Pic moving group of 26 ± 3 Myr by combining our results for V343 Normae with literature measurements for GJ 3305, which is another group member with resolved binary components and dynamical masses.

  8. FRD in optical fibres at low temperatures: investigations for Gemini's Wide-field Fibre Multi-Object Spectrograph

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. C.; de Oliveira, L. S.; Dos Santos, J. B.; Arruda, M. V.; Dos Santos, L. G. C.; Rodrigues, F.; de Castro, F. L. F.

    2011-06-01

    While there is no direct evidence for the deterioration in Focal Ratio Degradation (FRD) of optical fibres in severe temperature gradients, the fibre ends inserted into metallic containment devices such as steel ferrules can be a source of stress, and hence increased FRD at low temperatures. In such conditions, instruments using optical fibres may suffer some increase in FRD and consequent loss of system throughput when they are working in environments with significant thermal gradients, a common characteristic of ground-based observatories. In this paper we present results of experiments with optical fibres inserted in different materials as a part of our prototyping study for Gemini's Wide-field Multi-Object Spectrograph (WFMOS) project. Thermal effects and the use of new holding techniques will be discussed in the context of Integral Field Units and multi-fibres systems. In this work, we have used careful methodologies that give absolute measurements of FRD to quantify the advantages of using epoxy-based composites rather than metals as support structures for the fibre ends. This is shown to be especially important in minimizing thermally induced stresses in the fibre terminations. Not only is this important for optimizing fibre spectrograph performance but the benefits of using such materials are demonstrated in the minimization of positional variations and the avoidance of metal-to-glass delamination. Furthermore, by impregnating the composites with small zirconium oxide particles the composite materials supply their own fine polishing grit which aids significantly to the optical quality of the finished product.

  9. A uGNI-Based Asynchronous Message-driven Runtime System for Cray Supercomputers with Gemini Interconnect

    SciTech Connect

    Sun, Yanhua; Zheng, Gengbin; Olson, Ryan M; Jones, Terry R; Kale, Laxmikant V

    2012-01-01

    Gemini as the network for new Cray XE/XT systems features low latency, high bandwidth and strong scalability. Its hardware support for remote direct memory access enables efficient implementation of the global address space programming languages. Although the Generic Network Interface (GNI) is designed to support message-passing applications, it is still challenging to attain good performance for applications written in alternative programming models, such as the message-driven programming model. In our earlier work we showed that CHARM++, an object-oriented message-driven programming model, scales up to the full Jaguar Cray machine. In this paper, we describe a general and light-weight asynchronous Low-level RunTime System (LRTS) for CHARM+, and its implementation on the uGNI software stack for Cray XE systems. Several techniques are presented to exploit the uGNI capability by reducing memory copy and registration overhead, taking advantage of persistent communication, and improving intra-node communication. Our micro-benchmark results demonstrate that the uGNI-based runtime system outperforms the MPI-based implementation by up to 50% in terms of message latency. For communication intensive applications such as N-Queens, this implementation scales up to 15,360 cores of a Cray XE6 machine and is 70% faster than an MPI-based implementation. In molecular dynamics application NAMD, the performance is also considerably improved by as high as 18%.

  10. SEARCHING FOR BINARY Y DWARFS WITH THE GEMINI MULTI-CONJUGATE ADAPTIVE OPTICS SYSTEM (GeMS)

    SciTech Connect

    Opitz, Daniela; Tinney, C. G.; Faherty, Jacqueline K.; Sweet, Sarah; Gelino, Christopher R.; Kirkpatrick, J. Davy

    2016-03-01

    The NASA Wide-field Infrared Survey Explorer (WISE) has discovered almost all the known members of the new class of Y-type brown dwarfs. Most of these Y dwarfs have been identified as isolated objects in the field. It is known that binaries with L- and T-type brown dwarf primaries are less prevalent than either M-dwarf or solar-type primaries, they tend to have smaller separations and are more frequently detected in near-equal mass configurations. The binary statistics for Y-type brown dwarfs, however, are sparse, and so it is unclear if the same trends that hold for L- and T-type brown dwarfs also hold for Y-type ones. In addition, the detection of binary companions to very cool Y dwarfs may well be the best means available for discovering even colder objects. We present results for binary properties of a sample of five WISE Y dwarfs with the Gemini Multi-Conjugate Adaptive Optics System. We find no evidence for binary companions in these data, which suggests these systems are not equal-luminosity (or equal-mass) binaries with separations larger than ∼0.5–1.9 AU. For equal-mass binaries at an age of 5 Gyr, we find that the binary binding energies ruled out by our observations (i.e., 10{sup 42} erg) are consistent with those observed in previous studies of hotter ultra-cool dwarfs.

  11. PEERING INTO THE GIANT-PLANET-FORMING REGION OF THE TW HYDRAE DISK WITH THE GEMINI PLANET IMAGER

    SciTech Connect

    Rapson, Valerie A.; Kastner, Joel H.; Millar-Blanchaer, Maxwell A.; Dong, Ruobing

    2015-12-20

    We present Gemini Planet Imager (GPI) adaptive optics near-infrared images of the giant-planet-forming regions of the protoplanetary disk orbiting the nearby (D = 54 pc), pre-main-sequence (classical T Tauri) star TW Hydrae. The GPI images, which were obtained in coronagraphic/polarimetric mode, exploit starlight scattered off small dust grains to elucidate the surface density structure of the TW Hya disk from ∼80 AU to within ∼10 AU of the star at ∼1.5 AU resolution. The GPI polarized intensity images unambiguously confirm the presence of a gap in the radial surface brightness distribution of the inner disk. The gap is centered near ∼23 AU, with a width of ∼5 AU and a depth of ∼50%. In the context of recent simulations of giant-planet formation in gaseous, dusty disks orbiting pre-main-sequence stars, these results indicate that at least one young planet with a mass ∼0.2 M{sub J} could be present in the TW Hya disk at an orbital semimajor axis similar to that of Uranus. If this (proto)planet is actively accreting gas from the disk, it may be readily detectable by GPI or a similarly sensitive, high-resolution infrared imaging system.

  12. NMR study of the dynamics of cationic gemini surfactant 14-2-14 in mixed solutions with conventional surfactants.

    PubMed

    Jiang, Yan; Lu, Xing-Yu; Chen, Hong; Mao, Shi-Zhen; Liu, Mai-Li; Luo, Ping-Ya; Du, You-Ru

    2009-06-18

    Three kinds of conventional surfactants, namely, two nonionic surfactants [polyethylene glycol (23) lauryl ether (Brij-35) and Triton X-100 (TX-100)], one cationic surfactant [n-tetradecyltrimethyl ammonium bromide (TTAB)], and an anionic surfactant [sodium n-dodecyl sulfate (SDS)}, were mixed into the quaternary ammonium gemini surfactant [C(14)H(29)N(+)(CH(3))(2)](2)(CH(2))(2).2Br(-) (14-2-14) in aqueous solution. The exchange rate constants between 14-2-14 molecules in the mixed micelles and those in the bulk solution were detected using two nuclear magnetic resonance (NMR) methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). The results obtained from these two methods were consistent. Both showed that mixing a nonionic conventional surfactant, either Brij-35 or TX-100, enhanced the exchange process between the 14-2-14 molecules in the mixed micelles and those in the bulk solution. In contrast, the anionic surfactant SDS and the cationic surfactant TTAB slowed the process slightly.

  13. First scattered-light image of the debris disk around HD 131835 with the Gemini Planet Imager

    DOE PAGES

    Hung, Li -Wei; Duchêne, Gaspard; Arriaga, Pauline; ...

    2015-12-09

    Here, we present the first scattered-light image of the debris disk around HD 131835 in the H band using the Gemini Planet Imager. HD 131835 is a ~15 Myr old A2IV star at a distance of ~120 pc in the Sco-Cen OB association. We detect the disk only in polarized light and place an upper limit on the peak total intensity. No point sources resembling exoplanets were identified. Compared to its mid-infrared thermal emission, in scattered light the disk shows similar orientation but different morphology. The scattered-light disk extends from ~75 to ~210 AU in the disk plane with roughlymore » flat surface density. Our Monte Carlo radiative transfer model can describe the observations with a model disk composed of a mixture of silicates and amorphous carbon. In addition to the obvious brightness asymmetry due to stronger forward scattering, we discover a weak brightness asymmetry along the major axis, with the northeast side being 1.3 times brighter than the southwest side at a 3σ level.« less

  14. The Triaxial Ellipsoid Diameters and Rotational Pole of Asteroid (9) Metis from AO at Gemini and Keck

    NASA Astrophysics Data System (ADS)

    Drummond, Jack D.; Merline, W. J.; Conrad, A.; Dumas, C.; Tamblyn, P.; Christou, J.; Carry, B.; Chapman, C.

    2012-10-01

    From Adaptive Optics (AO) images of (9) Metis at 14 epochs over 2008 December 8 and 9 at Gemini North, triaxial ellipsoid diameters of 218x175x112 km are derived with fitting uncertainties of 3x3x47 km. However, by including just two more AO images from Keck-II in June and August of 2003 in a global fit, the fitting uncertainty of the small axis drops by more than a third because of the lower sub-Earth latitude afforded in 2003 (-28°) compared to 2008 (+47°), and the triaxial ellipsoid diameters become 218x175x129 km with fitting uncertainties of 3x3x14 km. We have estimated the systematic uncertainty of our method to be 4.1, 2.7, and 3.8%, respectively, for the three diameters. These values were recently derived (Drummond et al., in prep) from a comparison of KOALA (Carry et al, Planetary and Space Science 66, 200-212) and our triaxial ellipsoid analysis of four asteroids. Quadratically adding this systematic error with the fitting error, the total uncertainty for Metis becomes 9x5x15 km. Concurrently, we find an EQJ2000 rotational pole at [RA; Dec]=[185° +19°] or in ecliptic coordinates, [λ ; β ]=[176° +20°] (ECJ2000).

  15. Astrometric Confirmation and Preliminary Orbital Parameters of the Young Exoplanet 51 Eridani b with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    De Rosa, Robert J.; Nielsen, Eric L.; Blunt, Sarah C.; Graham, James R.; Konopacky, Quinn M.; Marois, Christian; Pueyo, Laurent; Rameau, Julien; Ryan, Dominic M.; Wang, Jason J.; Bailey, Vanessa; Chontos, Ashley; Fabrycky, Daniel C.; Follette, Katherine B.; Macintosh, Bruce; Marchis, Franck; Ammons, S. Mark; Arriaga, Pauline; Chilcote, Jeffrey K.; Cotten, Tara H.; Doyon, René; Duchêne, Gaspard; Esposito, Thomas M.; Fitzgerald, Michael P.; Gerard, Benjamin; Goodsell, Stephen J.; Greenbaum, Alexandra Z.; Hibon, Pascale; Ingraham, Patrick; Johnson-Groh, Mara; Kalas, Paul G.; Lafrenière, David; Maire, Jerome; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Oppenheimer, Rebecca; Patel, Rahul I.; Patience, Jennifer L.; Perrin, Marshall D.; Rajan, Abhijith; Rantakyrö, Fredrik T.; Ruffio, Jean-Baptiste; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Tran, Debby; Vasisht, Gautam; Ward-Duong, Kimberly; Wolff, Schuyler G.

    2015-11-01

    We present new Gemini Planet Imager observations of the young exoplanet 51 Eridani b that provide further evidence that the companion is physically associated with 51 Eridani. Combining this new astrometric measurement with those reported in the literature, we significantly reduce the posterior probability that 51 Eridani b is an unbound foreground or background T-dwarf in a chance alignment with 51 Eridani to 2 × 10-7, an order of magnitude lower than previously reported. If 51 Eridani b is indeed a bound object, then we have detected orbital motion of the planet between the discovery epoch and the latest epoch. By implementing a computationally efficient Monte Carlo technique, preliminary constraints are placed on the orbital parameters of the system. The current set of astrometric measurements suggest an orbital semimajor axis of {14}-3+7 AU, corresponding to a period of {41}-12+35 years (assuming a mass of 1.75 M⊙ for the central star), and an inclination of {138}-13+15 deg. The remaining orbital elements are only marginally constrained by the current measurements. These preliminary values suggest an orbit that does not share the same inclination as the orbit of the distant M-dwarf binary, GJ 3305, which is a wide physically bound companion to 51 Eridani.

  16. Polarimetry with the Gemini Planet Imager: Methods, Performance at First Light, and the Circumstellar Ring around HR 4796A

    NASA Astrophysics Data System (ADS)

    Perrin, Marshall D.; Duchene, Gaspard; Millar-Blanchaer, Max; Fitzgerald, Michael P.; Graham, James R.; Wiktorowicz, Sloane J.; Kalas, Paul G.; Macintosh, Bruce; Bauman, Brian; Cardwell, Andrew; Chilcote, Jeffrey; De Rosa, Robert J.; Dillon, Daren; Doyon, René; Dunn, Jennifer; Erikson, Darren; Gavel, Donald; Goodsell, Stephen; Hartung, Markus; Hibon, Pascale; Ingraham, Patrick; Kerley, Daniel; Konapacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marois, Christian; Mittal, Tushar; Morzinski, Katie M.; Oppenheimer, B. R.; Palmer, David W.; Patience, Jennifer; Poyneer, Lisa; Pueyo, Laurent; Rantakyrö, Fredrik T.; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Soummer, Rémi; Sivaramakrishnan, Anand; Song, Inseok; Thomas, Sandrine; Wallace, J. Kent; Wang, Jason J.; Wolff, Schuyler G.

    2015-02-01

    We present the first results from the polarimetry mode of the Gemini Planet Imager (GPI), which uses a new integral field polarimetry architecture to provide high contrast linear polarimetry with minimal systematic biases between the orthogonal polarizations. We describe the design, data reduction methods, and performance of polarimetry with GPI. Point-spread function (PSF) subtraction via differential polarimetry suppresses unpolarized starlight by a factor of over 100, and provides sensitivity to circumstellar dust reaching the photon noise limit for these observations. In the case of the circumstellar disk around HR 4796A, GPI's advanced adaptive optics system reveals the disk clearly even prior to PSF subtraction. In polarized light, the disk is seen all the way in to its semi-minor axis for the first time. The disk exhibits surprisingly strong asymmetry in polarized intensity, with the west side >~ 9 times brighter than the east side despite the fact that the east side is slightly brighter in total intensity. Based on a synthesis of the total and polarized intensities, we now believe that the west side is closer to us, contrary to most prior interpretations. Forward scattering by relatively large silicate dust particles leads to the strong polarized intensity on the west side, and the ring must be slightly optically thick in order to explain the lower brightness in total intensity there. These findings suggest that the ring is geometrically narrow and dynamically cold, perhaps shepherded by larger bodies in the same manner as Saturn's F ring.

  17. Chiral discrimination of a gemini-type surfactant with rigid spacer at the air-water interface.

    PubMed

    Shankar, B Vijai; Patnaik, Archita

    2007-10-04

    Spontaneous separation of chiral phases was observed in the monolayers of a racemate of gemini-type twin-tailed, twin-chiral amphiphiles, (2R,3R)-(+)-bis(decyloxy)succinic acid and (2S,3S)-(-)-bis(decyloxy)succinic acid. The pressure-area isotherms of the interfacial monolayers formed at the liquid-air interface, and the 2D lattice structures studied through surface probe measurements revealed that the racemate exhibits a homochiral discrimination of the enantiomers in two dimensions. An enantiomeric excess (e,e) of 20% was sufficient to break the chiral symmetry at the air-water interface for a homochiral interaction. Langmuir monolayers on ZnCl2 and CaCl2 subphases manifested chiral discrimination with Zn2+ evidencing homochiral interaction with a chelate-type complex, whereas Ca2+ resulted in a heterochiral interaction forming an ionic-type complex. For the chiral asymmetric units, oblique and rectangular unit cells of the racemic monolayer had exclusive requirements of homo- and heterochiral recognitions for Zn2+ and Ca2+ ions, respectively. Monolayers transferred from the condensed phase at 25 mN/m onto hydrophilic Si(100) and quartz substrates revealed the formation of bilayers through transfer-induced monolayer buckling. The emergence of homochiral discrimination was explained using the effective-pair-potential (EPP) approach.

  18. Peering into the Giant-planet-forming Region of the TW Hydrae Disk with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Rapson, Valerie A.; Kastner, Joel H.; Millar-Blanchaer, Maxwell A.; Dong, Ruobing

    2015-12-01

    We present Gemini Planet Imager (GPI) adaptive optics near-infrared images of the giant-planet-forming regions of the protoplanetary disk orbiting the nearby (D = 54 pc), pre-main-sequence (classical T Tauri) star TW Hydrae. The GPI images, which were obtained in coronagraphic/polarimetric mode, exploit starlight scattered off small dust grains to elucidate the surface density structure of the TW Hya disk from ∼80 AU to within ∼10 AU of the star at ∼1.5 AU resolution. The GPI polarized intensity images unambiguously confirm the presence of a gap in the radial surface brightness distribution of the inner disk. The gap is centered near ∼23 AU, with a width of ∼5 AU and a depth of ∼50%. In the context of recent simulations of giant-planet formation in gaseous, dusty disks orbiting pre-main-sequence stars, these results indicate that at least one young planet with a mass ∼0.2 MJ could be present in the TW Hya disk at an orbital semimajor axis similar to that of Uranus. If this (proto)planet is actively accreting gas from the disk, it may be readily detectable by GPI or a similarly sensitive, high-resolution infrared imaging system.

  19. FIRST SCATTERED-LIGHT IMAGE OF THE DEBRIS DISK AROUND HD 131835 WITH THE GEMINI PLANET IMAGER

    SciTech Connect

    Hung, Li-Wei; Arriaga, Pauline; Fitzgerald, Michael P.; Esposito, Thomas M.; Duchêne, Gaspard; Kalas, Paul G.; De Rosa, Robert J.; Graham, James R.; Maire, Jérôme; Chilcote, Jeffrey K.; Marois, Christian; Millar-Blanchaer, Maxwell A.; Bruzzone, Sebastian; Rajan, Abhijith; Pueyo, Laurent; Wolff, Schuyler G.; Chen, Christine H.; Konopacky, Quinn; Ammons, S. Mark; Draper, Zachary H.; and others

    2015-12-10

    We present the first scattered-light image of the debris disk around HD 131835 in the H band using the Gemini Planet Imager. HD 131835 is a ∼15 Myr old A2IV star at a distance of ∼120 pc in the Sco-Cen OB association. We detect the disk only in polarized light and place an upper limit on the peak total intensity. No point sources resembling exoplanets were identified. Compared to its mid-infrared thermal emission,  in scattered light the disk shows similar orientation but different morphology. The scattered-light disk extends from ∼75 to ∼210 AU in the disk plane with roughly flat surface density. Our Monte Carlo radiative transfer model can describe the observations with a model disk composed of a mixture of silicates and amorphous carbon. In addition to the obvious brightness asymmetry due to stronger forward scattering, we discover a weak brightness asymmetry along the major axis, with the northeast side being 1.3 times brighter than the southwest side at a 3σ level.

  20. Searching for Binary Y Dwarfs with the Gemini Multi-conjugate Adaptive Optics System (GeMS)

    NASA Astrophysics Data System (ADS)

    Opitz, Daniela; Tinney, C. G.; Faherty, Jacqueline K.; Sweet, Sarah; Gelino, Christopher R.; Kirkpatrick, J. Davy

    2016-03-01

    The NASA Wide-field Infrared Survey Explorer (WISE) has discovered almost all the known members of the new class of Y-type brown dwarfs. Most of these Y dwarfs have been identified as isolated objects in the field. It is known that binaries with L- and T-type brown dwarf primaries are less prevalent than either M-dwarf or solar-type primaries, they tend to have smaller separations and are more frequently detected in near-equal mass configurations. The binary statistics for Y-type brown dwarfs, however, are sparse, and so it is unclear if the same trends that hold for L- and T-type brown dwarfs also hold for Y-type ones. In addition, the detection of binary companions to very cool Y dwarfs may well be the best means available for discovering even colder objects. We present results for binary properties of a sample of five WISE Y dwarfs with the Gemini Multi-Conjugate Adaptive Optics System. We find no evidence for binary companions in these data, which suggests these systems are not equal-luminosity (or equal-mass) binaries with separations larger than ˜0.5-1.9 AU. For equal-mass binaries at an age of 5 Gyr, we find that the binary binding energies ruled out by our observations (i.e., 1042 erg) are consistent with those observed in previous studies of hotter ultra-cool dwarfs.

  1. Astrometric confirmation and preliminary orbital parameters of the young exoplanet 51 Eridani b with the Gemini Planet Imager

    SciTech Connect

    De Rosa, Robert J.; Nielsen, Eric L.; Blunt, Sarah C.; Graham, James R.; Konopacky, Quinn M.; Marois, Christian; Pueyo, Laurent; Rameau, Julien; Ryan, Dominic M.; Wang, Jason J.; Bailey, Vanessa; Chontos, Ashley; Fabrycky, Daniel C.; Follette, Katherine B.; Macintosh, Bruce; Marchis, Franck; Ammons, S. Mark; Arriaga, Pauline; Chilcote, Jeffrey K.; Cotten, Tara H.; Doyon, René; Duchêne, Gaspard; Fitzgerald, Michael P.; Gerard, Benjamin; Goodsell, Stephen J.; Greenbaum, Alexandra Z.; Hibon, Pascale; Ingraham, Patrick; Johnson-Groh, Mara; Kalas, Paul G.; Lafrenière, David; Maire, Jerome; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Oppenheimer, Rebecca; Patel, Rahul I.; Patience, Jennifer L.; Perrin, Marshall D.; Rajan, Abhijith; Rantakyrö, Fredrik T.; Ruffio, Jean-Baptiste; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Tran, Debby; Vasisht, Gautam; Ward-Duong, Kimberly; Wolff, Schuyler G.

    2015-11-13

    We present new Gemini Planet Imager observations of the young exoplanet 51 Eridani b that provide further evidence that the companion is physically associated with 51 Eridani. Combining this new astrometric measurement with those reported in the literature, we significantly reduce the posterior probability that 51 Eridani b is an unbound foreground or background T-dwarf in a chance alignment with 51 Eridani to 2 × 10–7, an order of magnitude lower than previously reported. If 51 Eridani b is indeed a bound object, then we have detected orbital motion of the planet between the discovery epoch and the latest epoch. By implementing a computationally efficient Monte Carlo technique, preliminary constraints are placed on the orbital parameters of the system. The current set of astrometric measurements suggest an orbital semimajor axis of ${14}_{-3}^{+7}$ AU, corresponding to a period of ${41}_{-12}^{+35}$ years (assuming a mass of 1.75 M⊙ for the central star), and an inclination of ${138}_{-13}^{+15}$ deg. The remaining orbital elements are only marginally constrained by the current measurements. As a result, these preliminary values suggest an orbit that does not share the same inclination as the orbit of the distant M-dwarf binary, GJ 3305, which is a wide physically bound companion to 51 Eridani.

  2. Astrometric confirmation and preliminary orbital parameters of the young exoplanet 51 Eridani b with the Gemini Planet Imager

    DOE PAGES

    De Rosa, Robert J.; Nielsen, Eric L.; Blunt, Sarah C.; ...

    2015-11-13

    We present new Gemini Planet Imager observations of the young exoplanet 51 Eridani b that provide further evidence that the companion is physically associated with 51 Eridani. Combining this new astrometric measurement with those reported in the literature, we significantly reduce the posterior probability that 51 Eridani b is an unbound foreground or background T-dwarf in a chance alignment with 51 Eridani to 2 × 10–7, an order of magnitude lower than previously reported. If 51 Eridani b is indeed a bound object, then we have detected orbital motion of the planet between the discovery epoch and the latest epoch. By implementing a computationally efficient Monte Carlo technique, preliminary constraints are placed on the orbital parameters of the system. The current set of astrometric measurements suggest an orbital semimajor axis ofmore » $${14}_{-3}^{+7}$$ AU, corresponding to a period of $${41}_{-12}^{+35}$$ years (assuming a mass of 1.75 M⊙ for the central star), and an inclination of $${138}_{-13}^{+15}$$ deg. The remaining orbital elements are only marginally constrained by the current measurements. As a result, these preliminary values suggest an orbit that does not share the same inclination as the orbit of the distant M-dwarf binary, GJ 3305, which is a wide physically bound companion to 51 Eridani.« less

  3. The synthesis and structure of gemini QASs of 1,4:3,6-dianhydro-L-iditol

    NASA Astrophysics Data System (ADS)

    Sikora, Karol; Nowacki, Andrzej; Sikorski, Artur; Dmochowska, Barbara

    2015-12-01

    New, efficient, straightforward method of synthesizing quaternary diammonium salts of 1,4:3,6-dianhydro-L-iditol have been developed. This paper presents the synthesis and structural analysis of diammonium (gemini) salts, including their X-ray diffraction analysis, wherein the linking structure of nitrogen atoms consists of two fused furanoid rings. 1,4:3,6-dianhydro-2,5-di-O-triflyl-D-mannitol and four tertiary amines, i.e., 4-(N,N-dimethylamino)pyridine (DMAP), pyridine, trimethylamine and N,N-dimethyloctylamine, were used for the synthesis. All the syntheses were carried out under mild conditions by the direct nucleophilic displacement of the O-triflil group by the amine. Walden inversion of configuration at C2 and C5 atoms has occurred during the reaction, giving products with L-ido configuration. Furthermore, NMR and X-ray conformational analysis of 1,4:3,6-dianhydrohexitol residue was done. In most cases furanoid rings adopt the twisted conformation both in the crystal and in solution.

  4. Comparison between the removal of phenol and catechol by modified montmorillonite with two novel hydroxyl-containing Gemini surfactants.

    PubMed

    Liu, Yuening; Gao, Manglai; Gu, Zheng; Luo, Zhongxin; Ye, Yage; Lu, Laifu

    2014-02-28

    Na-montmorillonites were modified with two novel hydroxyl-containing Gemini surfactants, 1,3-bis(hexadecyldimethylammonio)-2-hydroxypropane dichloride (BHHP) and 1,3-bis(octyldimethylammonio)-2-hydroxypropane dichloride (BOHP), via ion-exchange reaction in this study. The modified samples were characterized by X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy. Phenol and catechol were removed from aqueous solution by these two kinds of organo-montmorillonites in a batch system. Important parameters have been investigated, which affect the adsorption efficiency, such as the amount of modifier, temperature, pH and contact time. The adsorption kinetics of phenol and catechol were discussed using pseudo-first-order, pseudo-second-order and intra-particle diffusion model. It indicated that the experimental data fitted very well with the pseudo-second-order kinetic model, and the equilibrium adsorption data was proved in good agreement with the Langmuir isotherm. The result also showed the adsorption capacity of catechol was higher than that of phenol in the same conditions, which might result from the extra hydroxyl in the structure of catechol. Thermodynamic quantities such as Gibbs free energy (ΔG°), the enthalpy (ΔH°), and the entropy change of sorption (ΔS°) were also determined. These parameters suggested the adsorption of phenol was a spontaneous and exothermic process, while the sorption of catechol was endothermic.

  5. First scattered-light image of the debris disk around HD 131835 with the Gemini Planet Imager

    SciTech Connect

    Hung, Li -Wei; Duchêne, Gaspard; Arriaga, Pauline; Fitzgerald, Michael P.; Maire, Jérôme; Marois, Christian; Millar-Blanchaer, Maxwell A.; Bruzzone, Sebastian; Rajan, Abhijith; Pueyo, Laurent; Kalas, Paul G.; De Rosa, Robert J.; Graham, James R.; Konopacky, Quinn; Wolff, Schuyler G.; Ammons, S. Mark; Chen, Christine H.; Chilcote, Jeffrey K.; Draper, Zachary H.; Esposito, Thomas M.; Gerard, Benjamin; Goodsell, Stephen; Greenbaum, Alexandra; Hibon, Pascale; Hinkley, Sasha; Macintosh, Bruce; Marchis, Franck; Metchev, Stanimir; Nielsen, Eric L.; Oppenheimer, Rebecca; Patience, Jennifer L.; Perrin, Marshall D.; Rantakyrö, Fredrik T.; Sivaramakrishnan, Anand; Wang, Jason J.; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.

    2015-12-09

    Here, we present the first scattered-light image of the debris disk around HD 131835 in the H band using the Gemini Planet Imager. HD 131835 is a ~15 Myr old A2IV star at a distance of ~120 pc in the Sco-Cen OB association. We detect the disk only in polarized light and place an upper limit on the peak total intensity. No point sources resembling exoplanets were identified. Compared to its mid-infrared thermal emission, in scattered light the disk shows similar orientation but different morphology. The scattered-light disk extends from ~75 to ~210 AU in the disk plane with roughly flat surface density. Our Monte Carlo radiative transfer model can describe the observations with a model disk composed of a mixture of silicates and amorphous carbon. In addition to the obvious brightness asymmetry due to stronger forward scattering, we discover a weak brightness asymmetry along the major axis, with the northeast side being 1.3 times brighter than the southwest side at a 3σ level.

  6. A microscopic model of gemini surfactants: Self-assemblies in water and at air-water interface

    NASA Astrophysics Data System (ADS)

    Maiti, Prabal K.; Chowdhury, Debashish

    1998-09-01

    We report the results of large scale Monte Carlo simulations of novel microscopic models of gemini surfactants to elucidate (i) their spontaneous aggregation in bulk water and (ii) their spatial organization in a system where water is separated from the air above it by a sharp well-defined interface. We study the variation of the critical micellar concentration (CMC) with the variation of the (a) length of the spacer, (b) length of the hydrophobic tail, and (c) the bending rigidity of the hydrocarbon chains forming the spacer and the tail; some of the trends of variation are counterintuitive but are in excellent agreement with the available experimental results. Our simulations elucidate the effects of the geometrical shape, size, and density of the surfactant molecules, the ionic nature of the heads, and the hydrophobicity/hydrophilicity of the spacer not only on the shapes of the micellar aggregates and the magnitude of the CMC, but also on their conformations close to the air-water interface.

  7. Mensaje para alumnos y padres

    NASA Video Gallery

    El astronauta de la NASA José Hernández alienta a los estudiantes a que sigan sus sueños. Hernández también habla acerca del papel que juegan los padres para ayudar a que sus hijos hagan realidad s...

  8. Radiación

    NASA Video Gallery

    Fuera del capullo protector de la atmósfera terrestre, el universo está plagado de radiación dañina. Los astronautas que viven y trabajan en el espacio están expuestos no sólo a los rayos ultraviol...

  9. Entrenamiento con el traje espacial

    NASA Video Gallery

    Después de 10 paseos espaciales, el astronauta de la NASA Michael López- Alegría sabe bastante de trajes espaciales. En este video, López Alegría comparte su experiencia acerca del uso y el entrena...

  10. Optical design of MEMS-based infrared multi-object spectrograph concept for the Gemini South Telescope

    NASA Astrophysics Data System (ADS)

    Chen, Shaojie; Sivanandam, Suresh; Moon, Dae-Sik

    2016-08-01

    We discuss the optical design of an infrared multi-object spectrograph (MOS) concept that is designed to take advantage of the multi-conjugate adaptive optics (MCAO) corrected field at the Gemini South telescope. This design employs a unique, cryogenic MEMS-based focal plane mask to select target objects for spectroscopy by utilizing the Micro-Shutter Array (MSA) technology originally developed for the Near Infrared Spectrometer (NIRSpec) of the James Webb Space Telescope (JWST). The optical design is based on all spherical refractive optics, which serves both imaging and spectroscopic modes across the wavelength range of 0.9-2.5 μm. The optical system consists of a reimaging system, MSA, collimator, volume phase holographic (VPH) grisms, and spectrograph camera optics. The VPH grisms, which are VPH gratings sandwiched between two prisms, provide high dispersing efficiencies, and a set of several VPH grisms provide the broad spectral coverage at high throughputs. The imaging mode is implemented by removing the MSA and the dispersing unit out of the beam. We optimize both the imaging and spectrographic modes simultaneously, while paying special attention to the performance of the pupil imaging at the cold stop. Our current design provides a 1' ♢ 1' and a 0.5' ♢ 1' field of views for imaging and spectroscopic modes, respectively, on a 2048 × 2048 pixel HAWAII-2RG detector array. The spectrograph's slit width and spectral resolving power are 0.18'' and 3,000, respectively, and spectra of up to 100 objects can be obtained simultaneously. We present the overall results of simulated performance using optical model we designed.

  11. Integral Field Spectroscopy of the Low-mass Companion HD 984 B with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Johnson-Groh, Mara; Marois, Christian; De Rosa, Robert J.; Nielsen, Eric L.; Rameau, Julien; Blunt, Sarah; Vargas, Jeffrey; Ammons, S. Mark; Bailey, Vanessa P.; Barman, Travis S.; Bulger, Joanna; Chilcote, Jeffrey K.; Cotten, Tara; Doyon, René; Duchêne, Gaspard; Fitzgerald, Michael P.; Follette, Kate B.; Goodsell, Stephen; Graham, James R.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn M.; Larkin, James E.; Macintosh, Bruce; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Oppenheimer, Rebecca; Palmer, David W.; Patience, Jenny; Perrin, Marshall; Poyneer, Lisa A.; Pueyo, Laurent; Rajan, Abhijith; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Vega, David; Wallace, J. Kent; Wang, Jason J.; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2017-04-01

    We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager (GPI) as a part of the GPI Exoplanet Survey campaign. Images of HD 984 B were obtained in the J (1.12–1.3 μm) and H (1.50–1.80 μm) bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 au (70-year) orbit with a 68% confidence interval between 14 and 28 au, an eccentricity of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119° with a 68% confidence interval between 114° and 125°. To address the considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare them to known spectral types using field brown dwarf and low-mass star spectra and find a best-fit match of a field gravity M6.5 ± 1.5 spectral type with a corresponding temperature of {2730}-180+120 K. Photometry of the companion yields a luminosity of {log}({L}{bol}/{L}ȯ )=-2.88+/- 0.07 dex with DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34 ± 1 to 95 ± 4 M Jup. These results are consistent with previous measurements of the object.

  12. RESOLVING THE HD 100546 PROTOPLANETARY SYSTEM WITH THE GEMINI PLANET IMAGER: EVIDENCE FOR MULTIPLE FORMING, ACCRETING PLANETS

    SciTech Connect

    Currie, Thayne; Cloutier, Ryan; Brittain, Sean; Grady, Carol; Kuchner, Marc J.; Burrows, Adam; Muto, Takayuki; Kenyon, Scott J.

    2015-12-01

    We report Gemini Planet Imager H-band high-contrast imaging/integral field spectroscopy and polarimetry of the HD 100546, a 10 Myr old early-type star recently confirmed to host a thermal infrared (IR) bright (super-)Jovian protoplanet at wide separation, HD 100546 b. We resolve the inner disk cavity in polarized light, recover the thermal IR-bright arm, and identify one additional spiral arm. We easily recover HD 100546 b and show that much of its emission plausibly originates from an unresolved point source. The point-source component of HD 100546 b has extremely red IR colors compared to field brown dwarfs, qualitatively similar to young cloudy super-Jovian planets; however, these colors may instead indicate that HD 100546 b is still accreting material from a circumplanetary disk. Additionally, we identify a second point-source-like peak at r{sub proj} ∼ 14 AU, located just interior to or at the inner disk wall consistent with being a <10–20 M{sub J} candidate second protoplanet—“HD 100546 c”—and lying within a weakly polarized region of the disk but along an extension of the thermal IR-bright spiral arm. Alternatively, it is equally plausible that this feature is a weakly polarized but locally bright region of the inner disk wall. Astrometric monitoring of this feature over the next 2 years and emission line measurements could confirm its status as a protoplanet, rotating disk hot spot that is possibly a signpost of a protoplanet, or a stationary emission source from within the disk.

  13. Polarimetry with the Gemini Planet Imager. Methods, performance at first light, and the circumstellar ring around HR 4796A

    DOE PAGES

    Perrin, Marshall D.; Duchene, Gaspard; Millar-Blanchaer, Max; ...

    2015-01-28

    We report he first results from the polarimetry mode of the Gemini Planet Imager (GPI), which uses a new integral field polarimetry architecture to provide high contrast linear polarimetry with minimal systematic biases between the orthogonal polarizations. We describe the design, data reduction methods, and performance of polarimetry with GPI. Point-spread function (PSF) subtraction via differential polarimetry suppresses unpolarized starlight by a factor of over 100, and provides sensitivity to circumstellar dust reaching the photon noise limit for these observations. In the case of the circumstellar disk around HR 4796A, GPI’s advanced adaptive optics system reveals the disk clearly evenmore » prior to PSF subtraction. In polarized light, the disk is seen all the way in to its semi-minor axis for the first time. The disk exhibits surprisingly strong asymmetry in polarized intensity, with the west side ≳9 times brighter than the east side despite the fact that the east side is slightly brighter in total intensity. Based on a synthesis of the total and polarized intensities, we now believe that the west side is closer to us, contrary to most prior interpretations. Forward scattering by relatively large silicate dust particles leads to the strong polarized intensity on the west side, and the ring must be slightly optically thick in order to explain the lower brightness in total intensity there. In conclusion, these findings suggest that the ring is geometrically narrow and dynamically cold, perhaps shepherded by larger bodies in the same manner as Saturn’s F ring.« less

  14. A Combined Very Large Telescope and Gemini Study of the Atmosphere of the Directly Imaged Planet, Beta Pictoris b

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Burrows, Adam; Madhusudhan, Nikku; Fukagawa, Misato; Girard, Julien H.; Dawson, Rebekah; Murray-Clay, Ruth; Kenyon, Scott; Kuchner, Marc J.; Matsumura, Soko; Jayawardhana, Ray; Chambers, John; Bromley, Ben

    2013-01-01

    We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet Beta Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While Beta Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects-i.e., ? And b and 1RXJ 1609B-match Beta Pic b's JHKsL photometry and its 3.1 micron and 5 micron photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (approx. 60 micron)dust grains fail to reproduce the Beta Pic b spectrum. However, models incorporating thick clouds similar to those found forHR8799 bcde, but also with small (a fewmicrons) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles (a = 4 micron), we derive atmosphere parameters of log(g) = 3.8 +/- 0.2 and Teff = 1575-1650 K, an inferred mass of 7+4 -3 MJ, and a luminosity of log(L/L) approx. -3.80 +/- 0.02. The best-estimated planet radius, is approx. equal to 1.65 +/- 0.06 RJ, is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if Beta Pic b is younger than is approx. equal to 7 Myr, consistent with a late formation well after its host star's birth approx. 12+8 -4 Myr ago.

  15. A Combined Very Large Telescope and Gemini Study of the Atmosphere of the Directly Imaged Planet, β Pictoris b

    NASA Astrophysics Data System (ADS)

    Currie, Thayne; Burrows, Adam; Madhusudhan, Nikku; Fukagawa, Misato; Girard, Julien H.; Dawson, Rebekah; Murray-Clay, Ruth; Kenyon, Scott; Kuchner, Marc; Matsumura, Soko; Jayawardhana, Ray; Chambers, John; Bromley, Ben

    2013-10-01

    We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet β Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While β Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., κ And b and 1RXJ 1609B—match β Pic b's JHKsL' photometry and its 3.1 μm and 5 μm photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (~60 μm) dust grains fail to reproduce the β Pic b spectrum. However, models incorporating thick clouds similar to those found for HR 8799 bcde, but also with small (a few microns) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles (langarang = 4 μm), we derive atmosphere parameters of log (g) = 3.8 ± 0.2 and T eff = 1575-1650 K, an inferred mass of 7^{+4}_{-3} MJ , and a luminosity of log(L/L ⊙) ~-3.80 ± 0.02. The best-estimated planet radius, ≈1.65 ± 0.06 RJ , is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if β Pic b is younger than ≈7 Myr, consistent with a late formation well after its host star's birth ~12^{+8}_{-4} Myr ago.

  16. The Gemini/NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars

    NASA Astrophysics Data System (ADS)

    Biller, B.; Liu, M.; Wahhaj, Z.; Nielsen, E.; NICI Campaign Team

    2014-03-01

    We report results of a direct imaging survey for giant planets around 80 members of the β Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ΔH = 13.9 mag at 1'' in combined CH4 narrowband ADI+SDI mode and median contrasts of ΔH = 15.1 mag at 2'' in H-band ADI mode. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 ± 6 MJup, 16.4 ± 1.0 AU), CDñ35 2722B (31 ± 8 M Jup, 67 ± 4 AU), HD 12894B (0.46 ± 0.08 M., 15.7 ± 1.0 AU), and BD+07 1919C (0.20 ± 0.03 M., 12.5 ± 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 MJup companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars.

  17. Cationic gemini pyrrolidinium surfactants based sweeping-micellar electrokinetic chromatography for simultaneous detection of nine organic pollutants in environmental water.

    PubMed

    Tian, Yu; Wei, Ran; Cai, Bo; Dong, Jinfeng; Deng, Bin; Xiao, Yuxiu

    2016-12-02

    A series of novel cationic gemini surfactants with pyrrolidinium head groups, 1,1'-(butane-1,s-alkyl) bis (1-alkylpyrrolidinium) (Cn-4-CnPB, n=12, 14, 16), were employed as carriers in sweeping-micellar electrokinetic chromatography (sweeping-MEKC) for simultaneous detection of nine organic water pollutants, including polycyclic aromatic hydrocarbons, sulfonamides and steroids. The sweeping and separation conditions were optimized. Cn-4-CnPB (n=12, 14, 16) were compared with cetyltrimethylammonium bromide (CTAB) in terms of their abilities to preconcentrate and separate the nine analytes. Under the optimized conditions, the sensitivity enhancement factors based on the peak height (SEFsHeight) were ca. 310-580 of C16-4-C16PB, which were higher than those of C14-4-C14PB (120-290) and C12-4-C12PB (110-160). Meanwhile, the SEFsHeight of C16-4-C16PB were higher than those of 30% (v/v) methanol-modified CTAB (140-320). The C16-4-C16PB based sweeping-MEKC, coupled with offline solid phase extraction and UV detection (228nm), was used to analyze spiked environmental water samples. The nine analytes were successfully separated and detected. The limit of detection (S/N=3) was in range of 2.79-3.76ng/mL, and the recovery ranged from 70.8% to 95.5% with the RSDs less than 9.89%. This study confirms that the C16-4-C16PB based sweeping-MEKC has significant advantages over the CTAB based sweeping-MEKC and it is a promising method for sensitive and simultaneous detection of polycyclic aromatic hydrocarbons, sulfonamides and steroids in environmental water samples.

  18. Polarized Light Imaging of the HD 142527 Transition Disk with the Gemini Planet Imager: Dust around the Close-in Companion

    NASA Astrophysics Data System (ADS)

    Rodigas, Timothy J.; Follette, Katherine B.; Weinberger, Alycia; Close, Laird; Hines, Dean C.

    2014-08-01

    When giant planets form, they grow by accreting gas and dust. HD 142527 is a young star that offers a scaled-up view of this process. It has a broad, asymmetric ring of gas and dust beyond ~100 AU and a wide inner gap. Within the gap, a low-mass stellar companion orbits the primary star at just ~12 AU, and both the primary and secondary are accreting gas. In an attempt to directly detect the dusty counterpart to this accreted gas, we have observed HD 142527 with the Gemini Planet Imager in polarized light at Y band (0.95-1.14 μm). We clearly detect the companion in total intensity and show that its position and photometry are generally consistent with the expected values. We also detect a point source in polarized light that may be spatially separated by ~ a few AU from the location of the companion in total intensity. This suggests that dust is likely falling onto or orbiting the companion. Given the possible contribution of scattered light from this dust to previously reported photometry of the companion, the current mass limits should be viewed as upper limits only. If the dust near the companion is eventually confirmed to be spatially separated, this system would resemble a scaled-up version of the young planetary system inside the gap of the transition disk around LkCa 15. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministrio da Cincia, Tecnologia e Inovao (Brazil), and Ministerio de Ciencia, Tecnologa e Innovacin Productiva (Argentina).

  19. The Gemini NICI Planet-finding Campaign: Discovery of a Close Substellar Companion to the Young Debris Disk Star PZ Tel

    NASA Astrophysics Data System (ADS)

    Biller, Beth A.; Liu, Michael C.; Wahhaj, Zahed; Nielsen, Eric L.; Close, Laird M.; Dupuy, Trent J.; Hayward, Thomas L.; Burrows, Adam; Chun, Mark; Ftaclas, Christ; Clarke, Fraser; Hartung, Markus; Males, Jared; Reid, I. Neill; Shkolnik, Evgenya L.; Skemer, Andrew; Tecza, Matthias; Thatte, Niranjan; Alencar, Silvia H. P.; Artymowicz, Pawel; Boss, Alan; de Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane; Ida, Shigeru; Kuchner, Marc J.; Lin, Douglas; Toomey, Douglas

    2010-09-01

    We report the discovery of a tight substellar companion to the young solar analog PZ Tel, a member of the β Pic moving group observed with high-contrast adaptive optics imaging as part of the Gemini Near-Infrared Coronagraphic Imager Planet-Finding Campaign. The companion was detected at a projected separation of 16.4 ± 1.0 AU (0farcs33 ± 0farcs01) in 2009 April. Second-epoch observations in 2010 May demonstrate that the companion is physically associated and shows significant orbital motion. Monte Carlo modeling constrains the orbit of PZ Tel B to eccentricities >0.6. The near-IR colors of PZ Tel B indicate a spectral type of M7 ± 2 and thus this object will be a new benchmark companion for studies of ultracool, low-gravity photospheres. Adopting an age of 12+8 -4 Myr for the system, we estimate a mass of 36 ± 6 M Jup based on the Lyon/DUSTY evolutionary models. PZ Tel B is one of the few young substellar companions directly imaged at orbital separations similar to those of giant planets in our own solar system. Additionally, the primary star PZ Tel A shows a 70 μm emission excess, evidence for a significant quantity of circumstellar dust that has not been disrupted by the orbital motion of the companion. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  20. Effect of spacer length on the interfacial behavior of N,N'-bis(dimethylalkyl)-α,ω-alkanediammonium dibromide gemini surfactants in the absence and presence of ZnO nanoparticles.

    PubMed

    Fereidooni Moghadam, Tahereh; Azizian, Saeid; Wettig, Shawn

    2017-01-15

    In this paper the interfacial behavior of aqueous solutions of cationic gemini surfactants of the, N,N'-bis(dimethylalkyl)-α,ω-alkanediammoniumdibromide type (known as the 12-s-12 series), in the absence and presence of ZnO nanoparticles was studied. Equilibrium and dynamic interfacial tension between n-decane and aqueous surfactant solutions were investigated. It was concluded that the synergistic effect between surfactants and nanoparticles increases the surfactant efficiency with respect to reducing the interfacial tension. Moreover, the magnitude of the effect of ZnO nanoparticles on the interfacial tension decreases with increasing length of the spacer group in the gemini surfactant structure. Dynamic studies illustrate that the migration mechanism of gemini surfactants (regardless of the presence of ZnO) from the bulk to the interface was controlled by both diffusion and adsorption. The effect of spacer length on the contact angle and emulsion stability both with and without nanoparticles was also studied.

  1. THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS

    SciTech Connect

    Biller, Beth A.; Ftaclas, Christ; Liu, Michael C.; Wahhaj, Zahed; Nielsen, Eric L.; Hayward, Thomas L.; Hartung, Markus; Chun, Mark; Clarke, Fraser; Thatte, Niranjan; Shkolnik, Evgenya L.; Reid, I. Neill; Boss, Alan; Lin, Douglas; Alencar, Silvia H. P.; De Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane [Universidade de Sao Paulo, IAG and others

    2013-11-10

    We report results of a direct imaging survey for giant planets around 80 members of the β Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ΔH = 13.9 mag at 1'' in combined CH{sub 4} narrowband ADI+SDI mode and median contrasts of ΔH = 15.1 mag at 2'' in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with Near-Infrared Coronagraphic Imager (NICI) all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI Campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 ± 6 M{sub Jup}, 16.4 ± 1.0 AU), CD–35 2722B (31 ± 8 M{sub Jup}, 67 ± 4 AU), HD 12894B (0.46 ± 0.08 M{sub ☉}, 15.7 ± 1.0 AU), and BD+07 1919C (0.20 ± 0.03 M{sub ☉}, 12.5 ± 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M{sub Jup} companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50 AU as well. We restrict the frequency of 1-20 M{sub Jup} companions at semi-major axes from 10-50 AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars.

  2. A COMBINED VERY LARGE TELESCOPE AND GEMINI STUDY OF THE ATMOSPHERE OF THE DIRECTLY IMAGED PLANET, β PICTORIS b

    SciTech Connect

    Currie, Thayne; Jayawardhana, Ray; Burrows, Adam; Madhusudhan, Nikku; Fukagawa, Misato; Girard, Julien H.; Dawson, Rebekah; Murray-Clay, Ruth; Kenyon, Scott; Kuchner, Marc; Matsumura, Soko; Chambers, John; Bromley, Ben

    2013-10-10

    We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet β Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While β Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., κ And b and 1RXJ 1609B—match β Pic b's JHK{sub s}L' photometry and its 3.1 μm and 5 μm photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (∼60 μm) dust grains fail to reproduce the β Pic b spectrum. However, models incorporating thick clouds similar to those found for HR 8799 bcde, but also with small (a few microns) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles ((a) = 4 μm), we derive atmosphere parameters of log (g) = 3.8 ± 0.2 and T{sub eff} = 1575-1650 K, an inferred mass of 7{sup +4}{sub -3} M{sub J} , and a luminosity of log(L/L{sub ☉}) ∼–3.80 ± 0.02. The best-estimated planet radius, ≈1.65 ± 0.06 R{sub J} , is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if β Pic b is younger than ≈7 Myr, consistent with a late formation well after its host star's birth ∼12{sup +8}{sub -4} Myr ago.

  3. GEMINI SPECTROSCOPY OF THE SHORT-HARD GAMMA-RAY BURST GRB 130603B AFTERGLOW AND HOST GALAXY

    SciTech Connect

    Cucchiara, A.; Prochaska, J. X.; Werk, J.; Cenko, S. B.; Cardwell, A.; Turner, J.; Bloom, J. S.; Cobb, B. E.

    2013-11-10

    We present early optical photometry and spectroscopy of the afterglow and host galaxy of the bright short-duration gamma-ray burst GRB 130603B discovered by the Swift satellite. Using our Target of Opportunity program on the Gemini South telescope, our prompt optical spectra reveal a strong trace from the afterglow superimposed on continuum and emission lines from the z = 0.3568 ± 0.0005 host galaxy. The combination of a relatively bright optical afterglow (r' = 21.52 at Δt = 8.4 hr), together with an observed offset of 0.''9 from the host nucleus (4.8 kpc projected distance at z = 0.3568), allow us to extract a relatively clean spectrum dominated by afterglow light. Furthermore, the spatially resolved spectrum allows us to constrain the properties of the explosion site directly, and compare these with the host galaxy nucleus, as well as other short-duration GRB host galaxies. We find that while the host is a relatively luminous (L∼0.8 L{sup *}{sub B}), star-forming (SFR = 1.84 M{sub ☉} yr{sup –1}) galaxy with almost solar metallicity, the spectrum of the afterglow exhibits weak Ca II absorption features but negligible emission features. The explosion site therefore lacks evidence of recent star formation, consistent with the relatively long delay time distribution expected in a compact binary merger scenario. The star formation rate (SFR; both in an absolute sense and normalized to the luminosity) and metallicity of the host are both consistent with the known sample of short-duration GRB hosts and with recent results which suggest GRB 130603B emission to be the product of the decay of radioactive species produced during the merging process of a neutron-star-neutron-star binary ({sup k}ilonova{sup )}. Ultimately, the discovery of more events similar to GRB 130603B and their rapid follow-up from 8 m class telescopes will open new opportunities for our understanding of the final stages of compact-objects binary systems and provide crucial information

  4. THE GEMINI NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF GIANT PLANETS AROUND YOUNG B AND A STARS

    SciTech Connect

    Nielsen, Eric L.; Liu, Michael C.; Chun, Mark; Ftaclas, Christ; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.; Hartung, Markus; Alencar, Silvia H. P.; Artymowicz, Pawel; Boss, Alan; Clarke, Fraser; De Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane; Kuchner, Marc; Lin, Douglas N. C.; and others

    2013-10-10

    We have carried out high contrast imaging of 70 young, nearby B and A stars to search for brown dwarf and planetary companions as part of the Gemini NICI Planet-Finding Campaign. Our survey represents the largest, deepest survey for planets around high-mass stars (≈1.5-2.5 M{sub ☉}) conducted to date and includes the planet hosts β Pic and Fomalhaut. We obtained follow-up astrometry of all candidate companions within 400 AU projected separation for stars in uncrowded fields and identified new low-mass companions to HD 1160 and HIP 79797. We have found that the previously known young brown dwarf companion to HIP 79797 is itself a tight (3 AU) binary, composed of brown dwarfs with masses 58{sup +21}{sub -20} M{sub Jup} and 55{sup +20}{sub -19} M{sub Jup}, making this system one of the rare substellar binaries in orbit around a star. Considering the contrast limits of our NICI data and the fact that we did not detect any planets, we use high-fidelity Monte Carlo simulations to show that fewer than 20% of 2 M{sub ☉} stars can have giant planets greater than 4 M{sub Jup} between 59 and 460 AU at 95% confidence, and fewer than 10% of these stars can have a planet more massive than 10 M{sub Jup} between 38 and 650 AU. Overall, we find that large-separation giant planets are not common around B and A stars: fewer than 10% of B and A stars can have an analog to the HR 8799 b (7 M{sub Jup}, 68 AU) planet at 95% confidence. We also describe a new Bayesian technique for determining the ages of field B and A stars from photometry and theoretical isochrones. Our method produces more plausible ages for high-mass stars than previous age-dating techniques, which tend to underestimate stellar ages and their uncertainties.

  5. Interaction of bovine (BSA), rabbit (RSA), and porcine (PSA) serum albumins with cationic single-chain/gemini surfactants: a comparative study.

    PubMed

    Gull, Nuzhat; Sen, Priyankar; Khan, Rizwan Hasan; Kabir-ud-Din

    2009-10-06

    The interactions among bovine, rabbit, and porcine serum albumins and single-chain cationic surfactant cetyltrimethylammonium bromide (CTAB) versus its gemini counterpart (designated as G4) have been studied. The studies were carried out in an aqueous medium at pH 7.0 using UV, intrinsic and extrinsic fluorescence spectroscopy, and far-UV circular dichroism techniques. The results indicate that compared to CTAB, G4 interacts strongly with the serum albumins, resulting in a significantly larger unfolding or decrease in alpha-helical content as reflected by the significantly larger decrease in ellipticity in the far-UV range. Unlike CTAB, a remarkable increase in the alpha-helical content of BSA at 625 microM G4 and at 250 microM G4 for RSA and PSA is observed. The appearance of conformational changes and saturation points in the proteins occurs at considerably lower [G4] compared to [CTAB]. The results obtained from the multi-technique approach are ascribed to the stronger forces in G4 owing to the presence of two charged headgroups and two hydrocarbon tails. Keeping the results in view, it is suggested that the gemini surfactants may be effectively used in the renaturation of proteins produced in genetically engineered cells via the artificial chaperone protocol and may also prove useful in drug delivery as solubilizing agents to recover proteins from insoluble inclusion bodies.

  6. Novel serine-based gemini surfactants as chemical permeation enhancers of local anesthetics: A comprehensive study on structure-activity relationships, molecular dynamics and dermal delivery.

    PubMed

    Teixeira, Raquel S; Cova, Tânia F G G; Silva, Sérgio M C; Oliveira, Rita; do Vale, M Luísa C; Marques, Eduardo F; Pais, Alberto A C C; Veiga, Francisco J B

    2015-06-01

    This work aims at studying the efficacy of a series of novel biocompatible, serine-based surfactants as chemical permeation enhancers for two different local anesthetics, tetracaine and ropivacaine, combining an experimental and computational approach. The surfactants consist of gemini molecules structurally related, but with variations in headgroup charge (nonionic vs. cationic) and in the hydrocarbon chain lengths (main and spacer chains). In vitro permeation and molecular dynamics studies combined with cytotoxicity profiles were performed to investigate the permeation of both drugs, probe skin integrity, and rationalize the interactions at molecular level. Results show that these enhancers do not have significant deleterious effects on the skin structure and do not cause relevant changes on cell viability. Permeation across the skin is clearly improved using some of the selected serine-based gemini surfactants, namely the cationic ones with long alkyl chains and shorter spacer. This is noteworthy in the case of ropivacaine hydrochloride, which is not easily administered through the stratum corneum. Molecular dynamics results provide a mechanistic view of the surfactant action on lipid membranes that essentially corroborate the experimental observations. Overall, this study suggests the viability of these serine-based surfactants as suitable and promising delivery agents in pharmaceutical formulations.

  7. Absorption-enhancing effects of gemini surfactant on the intestinal absorption of poorly absorbed hydrophilic drugs including peptide and protein drugs in rats.

    PubMed

    Alama, Tammam; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-02-29

    In general, the intestinal absorption of small hydrophilic molecules and macromolecules like peptides, after oral administration is very poor. Absorption enhancers are considered to be one of the most promising agents to enhance the intestinal absorption of drugs. In this research, we focused on a gemini surfactant, a new type of absorption enhancer. The intestinal absorption of drugs, with or without sodium dilauramidoglutamide lysine (SLG-30), a gemini surfactant, was examined by an in situ closed-loop method in rats. The intestinal absorption of 5(6)-carboxyfluorescein (CF) and fluorescein isothiocyanate-dextrans (FDs) was significantly enhanced in the presence of SLG-30, such effect being reversible. Furthermore, the calcium levels in the plasma significantly decreased when calcitonin was co-administered with SLG-30, suggestive of the increased intestinal absorption of calcitonin. In addition, no significant increase in the of lactate dehydrogenase (LDH) activity or in protein release from the intestinal epithelium was observed in the presence of SLG-30, suggestive of the safety of this compound. These findings indicate that SLG-30 is an effective absorption-enhancer for improving the intestinal absorption of poorly absorbed drugs, without causing serious damage to the intestinal epithelium.

  8. Global Near-IR Maps of Io from Gemini-N and Keck Observations in 2010, with a Specific Emphasis on Kanehekili Fluctus, Janus Patera, and Loki Patera

    NASA Astrophysics Data System (ADS)

    De Pater, I.; Davies, A. G.; Adamkovics, M.; McGregor, A.; Observing Team, G.

    2013-12-01

    We have constructed global maps of Io from observations obtained at 1-5 μm in 2010 using the adaptive optics systems on the Keck and Gemini telescopes. We compare these maps with those obtained in 2001 [1]. Although the total emission from all hot spots combined at each wavelength is similar for the two years, the spatial brightness distribution is very different, a reflection of evolving style and magnitude of volcanic activity. In 2010 thermal emission in the near-infrared was dominated by Loki Patera and Kanehekili Fluctus. We also present new timelines of thermal emission from Kanehekili Fluctus and Loki and Janus Paterae, updating timelines in recent publications [2, 3] with additional Keck adaptive optics data obtained between 2003 and 2010. These new timelines are the most comprehensive plots ever produced of the volcanic thermal emission variability for these or any other locations on Io, utilizing data from multiple ground- and space-based assets. The timeline plot shows that in 2010 Kanehekili Fluctus (as seen by Gemini) was briefly exceptionally brighter than ever seen before, evidence of a short-lived but highly-energetic eruption episode. Acknowledgements: AGD is supported by a grant from the NASA OPR Program. References: [1] Marchis et al. (2005) Icarus, 176, 96-122. [2] Davies et al. (2012) Icarus, 221, 466-470. [3] Rathbun and Spencer (2010) Icarus, 209, 625-630.

  9. Effect of the nature of the spacer on gene transfer efficacies of novel thiocholesterol derived gemini lipids in different cell lines: a structure-activity investigation.

    PubMed

    Bajaj, Avinash; Kondaiah, Paturu; Bhattacharya, Santanu

    2008-04-24

    A structure-activity investigation was undertaken to see the effect of the nature of the spacer on the gene transfection efficacies of thiocholesterol-derived cationic gemini lipids possessing disulfide linkage between the cationic headgroup and the thiocholesterol moiety. Three gemini cationic lipids possessing hydrophobic flexible (-(CH 2) 5-; 1), hydrophobic rigid (-C 6H 4-; 2), and hydrophilic flexible (-CH 2-CH 2-O-CH 2-CH 2-; 3) spacer segments were synthesized. In HeLa cells, lipid formulations 1 and 2 were found to be more effective as compared to lipid 3 formulation. In HT1080 cell line, the order of transfectability was 3 > 1 > 2. Transfection studies in HeLa and HT1080 cell line also showed 40-50% transfection efficacy in the presence of 10% serum conditions. These formulations were also able to transfect gene across difficult cells like HaCaT. Cytotoxic studies showed the nontoxic nature of these lipid-DNA complexes at different N/P ratios used for transfection studies.

  10. A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes

    NASA Astrophysics Data System (ADS)

    He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

    2016-08-01

    Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them.

  11. 1–2.4 μm Near-IR Spectrum of the Giant Planet β Pictoris b Obtained with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Chilcote, Jeffrey; Pueyo, Laurent; De Rosa, Robert J.; Vargas, Jeffrey; Macintosh, Bruce; Bailey, Vanessa P.; Barman, Travis; Bauman, Brian; Bruzzone, Sebastian; Bulger, Joanna; Burrows, Adam S.; Cardwell, Andrew; Chen, Christine H.; Cotten, Tara; Dillon, Daren; Doyon, Rene; Draper, Zachary H.; Duchêne, Gaspard; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Follette, Katherine B.; Gavel, Donald; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hartung, Markus; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Nielsen, Eric L.; Norton, Andrew; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Schneider, Adam C.; Serio, Andrew; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Wang, Jason J.; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler

    2017-04-01

    Using the Gemini Planet Imager located at Gemini South, we measured the near-infrared (1.0–2.4 μm) spectrum of the planetary companion to the nearby, young star β Pictoris. We compare the spectrum obtained with currently published model grids and with known substellar objects and present the best matching models as well as the best matching observed objects. Comparing the empirical measurement of the bolometric luminosity to evolutionary models, we find a mass of 12.9 ± 0.2 {{ M }}{Jup}, an effective temperature of 1724 ± 15 K, a radius of 1.46 ± 0.01 {{ R }}{Jup}, and a surface gravity of {log}g=4.18+/- 0.01 [dex] (cgs). The stated uncertainties are statistical errors only, and do not incorporate any uncertainty on the evolutionary models. Using atmospheric models, we find an effective temperature of 1700–1800 K and a surface gravity of {log}g=3.5–4.0 [dex] depending upon the model. These values agree well with other publications and with “hot-start” predictions from planetary evolution models. Further, we find that the spectrum of β Pic b best matches a low surface gravity L2 ± 1 brown dwarf. Finally, comparing the spectrum to field brown dwarfs, we find the the spectrum best matches 2MASS J04062677–381210 and 2MASS J03552337+1133437.

  12. The bilateral action between EQ14-2-14 gemini surfactant and bovine serum albumin by DPI and 1H NMR

    NASA Astrophysics Data System (ADS)

    Wu, Gang; Jiang, Xiaohui; Zhou, Limei; Yang, Lijun; Wang, Ya; Xia, Guangqiang; Chen, Zhengjun; Duan, Ming

    2013-08-01

    Gemini surfactant diglycol bis-N-tetradecyl nicotinate dibromide (designed as EQ14-2-14) has been synthesized. The interaction between EQ14-2-14 and bovine serum albumin (BSA) was studied by dual polarization interferometry (DPI), proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR) and molecular docking. Owing to the binding of EQ14-2-14, the thickness and mass of BSA increased; refractive index (RI) and density firstly raised and then tended to a plateau. In addition, a decrease of α-helix was observed from 54.01% to 31.56% with an increase in random structure from 7.86% to 21.76%. Due to BSA intertwining, the proton resonance signals of EQ14-2-14 shifted up-field and relaxation time decreased with increasing concentration of BSA. The study of molecular docking indicated that EQ14-2-14 embedded into subdomain II of BSA by π-π stacking between the electron-deficit pyridinium rings in EQ14-2-14 and the electron-abundant pyrrole ring in Trp residues of BSA, by hydrogen bonding and by hydrophobic interaction. Therefore the present work offers a whole view of the interaction of BSA with a new gemini surfactant.

  13. A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes

    PubMed Central

    He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

    2016-01-01

    Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them. PMID:27561546

  14. Develando las propiedades del sistema inexplorado de cúmulos globulares de NGC 5044 a través de Gemini+GMOS

    NASA Astrophysics Data System (ADS)

    Scalia, M. C.; Faifer, F.; Smith Castelli, A.; Forte, J. C.; Cellone, S.; Bassino, L.

    2016-08-01

    We present the first photometric characterization and determination of radial velocities of globular cluster (GC) candidates belonging to the system of the elliptical galaxy NGC5044. This rich system presents several thousand candidates and its bimodal color distribution is dominated by blue GCs. We have spectroscopically confirmed 27 members of the system, with an averaged radial velocity of 2833kms. One of the confirmed members is a strong candidate to be the first Ultra-Compact Dwarf discovered in NGC5044.

  15. The Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS): The Role of Environment and Self-regulation in Galaxy Evolution at z ~ 1

    NASA Astrophysics Data System (ADS)

    Muzzin, Adam; Wilson, Gillian; Yee, H. K. C.; Gilbank, David; Hoekstra, Henk; Demarco, Ricardo; Balogh, Michael; van Dokkum, Pieter; Franx, Marijn; Ellingson, Erica; Hicks, Amalia; Nantais, Julie; Noble, Allison; Lacy, Mark; Lidman, Chris; Rettura, Alessandro; Surace, Jason; Webb, Tracy

    2012-02-01

    We evaluate the effects of environment and stellar mass on galaxy properties at 0.85 Gemini Cluster Astrophysics Spectroscopic Survey. We confirm that for galaxies with log M */M ⊙ > 9.3 the well-known correlations between environment and properties such as star-forming fraction (f SF), star formation rate (SFR), specific SFR (SSFR), D n (4000), and color are already in place at z ~ 1. We separate the effects of environment and stellar mass on galaxies by comparing the properties of star-forming and quiescent galaxies at fixed environment and fixed stellar mass. The SSFR of star-forming galaxies at fixed environment is correlated with stellar mass; however, at fixed stellar mass it is independent of environment. The same trend exists for the D n (4000) measures of both the star-forming and quiescent galaxies and shows that their properties are determined primarily by their stellar mass, not by their environment. Instead, it appears that environment's primary role is to control the fraction of star-forming galaxies. Using the spectra we identify candidate poststarburst galaxies and find that those with 9.3 < log M */M ⊙ < 10.7 are 3.1 ± 1.1 times more common in high-density regions compared to low-density regions. The clear association of poststarbursts with high-density regions as well as the lack of a correlation between the SSFRs and D n (4000)s of star-forming galaxies with their environment strongly suggests that at z ~ 1 the environmental-quenching timescale must be rapid. Lastly, we construct a simple quenching model which demonstrates that the lack of a correlation between the D n (4000) of quiescent galaxies and their environment results naturally if self quenching dominates over environmental quenching at z > 1, or if the evolution of the self-quenching rate mirrors the evolution of the environmental-quenching rate at z > 1, regardless of which

  16. Developing a Metadata Infrastructure to facilitate data driven science gateway and to provide Inspire/GEMINI compliance for CLIPC

    NASA Astrophysics Data System (ADS)

    Mihajlovski, Andrej; Plieger, Maarten; Som de Cerff, Wim; Page, Christian

    2016-04-01

    indicators Key is the availability of standardized metadata, describing indicator data and services. This will enable standardization and interoperability between the different distributed services of CLIPC. To disseminate CLIPC indicator data, transformed data products to enable impacts assessments and climate change impact indicators a standardized meta-data infrastructure is provided. The challenge is that compliance of existing metadata to INSPIRE ISO standards and GEMINI standards needs to be extended to further allow the web portal to be generated from the available metadata blueprint. The information provided in the headers of netCDF files available through multiple catalogues, allow us to generate ISO compliant meta data which is in turn used to generate web based interface content, as well as OGC compliant web services such as WCS and WMS for front end and WPS interactions for the scientific users to combine and generate new datasets. The goal of the metadata infrastructure is to provide a blueprint for creating a data driven science portal, generated from the underlying: GIS data, web services and processing infrastructure. In the presentation we will present the results and lessons learned.

  17. Gemini Near Infrared Field Spectrograph Observations of the Seyfert 2 Galaxy Mrk 573: In Situ Acceleration of Ionized and Molecular Gas off Fueling Flows

    NASA Astrophysics Data System (ADS)

    Fischer, Travis C.; Machuca, C.; Diniz, M. R.; Crenshaw, D. M.; Kraemer, S. B.; Riffel, R. A.; Schmitt, H. R.; Baron, F.; Storchi-Bergmann, T.; Straughn, A. N.; Revalski, M.; Pope, C. L.

    2017-01-01

    We present near-infrared and optical emission-line and stellar kinematics of the Seyfert 2 galaxy Mrk 573 using the Near-Infrared Field Spectrograph (NIFS) at Gemini North and Dual Imaging Spectrograph at Apache Point Observatory, respectively. By obtaining full kinematic maps of the infrared ionized and molecular gas and stellar kinematics in a ∼700 × 2100 pc2 circumnuclear region of Mrk 573, we find that kinematics within the Narrow-Line Region are largely due to a combination of both rotation and in situ acceleration of material originating in the host disk. Combining these observations with large-scale, optical long-slit spectroscopy that traces ionized gas emission out to several kpcs, we find that rotation kinematics dominate the majority of the gas. We find that outflowing gas extends to distances less than 1 kpc, suggesting that outflows in Seyfert galaxies may not be powerful enough to evacuate their entire bulges.

  18. Surface modification of poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer via covalent immobilization of nonionic sugar-based Gemini surfactants.

    PubMed

    Xin, Zhirong; Du, Binbin; Yan, Shunjie; Du, Shanshan; Ding, Jiaotong; Yang, Zongfeng; Ren, Wanzhong

    2014-07-01

    Gemini surfactants (GS) with sugar-containing head-groups and different alkyl chains were successfully prepared. Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer was grafted with glycidyl methacrylate (GMA) by means of UV-induced graft polymerization, and then the pGMA-grafted film was chemically immobilized with the GS. The surface graft polymerization was confirmed by ATR-FTIR and XPS. The wettability and hemocompatibility of the modified surface were characterized by means of water contact angle, protein adsorption, and platelet adhesion assays. The results showed that amphiphilic surfactant-containing polymer surfaces presented protein-resistant behavior and anti-platelet adhesion after functionalization with GS, GS1 and GS2. Besides, the hemocompatibility of the modified surface deteriorated as the length of hydrophobic chain of GS increased.

  19. A SLUGGS and Gemini/GMOS combined study of the elliptical galaxy M60: wide-field photometry and kinematics of the globular cluster system

    NASA Astrophysics Data System (ADS)

    Pota, Vincenzo; Brodie, Jean P.; Bridges, Terry; Strader, Jay; Romanowsky, Aaron J.; Villaume, Alexa; Jennings, Zach; Faifer, Favio R.; Pastorello, Nicola; Forbes, Duncan A.; Campbell, Ainsley; Usher, Christopher; Foster, Caroline; Spitler, Lee R.; Caldwell, Nelson; Forte, Juan C.; Norris, Mark A.; Zepf, Stephen E.; Beasley, Michael A.; Gebhardt, Karl; Hanes, David A.; Sharples, Ray M.; Arnold, Jacob A.

    2015-06-01

    We present new wide-field photometry and spectroscopy of the globular clusters (GCs) around NGC 4649 (M60), the third brightest galaxy in the Virgo cluster. Imaging of NGC 4649 was assembled from a recently obtained Hubble Space Telescope/Advanced Camera for Surveys mosaic, and new Subaru/Suprime-Cam and archival Canada-France-Hawaii Telescope/MegaCam data. About 1200 sources were followed up spectroscopically using combined observations from three multi-object spectrographs: Keck/Deep Imaging Multi-Object Spectrograph, Gemini/Gemini Multi-Object Spectrograph and Multiple Mirror Telescope/Hectospec. We confirm 431 unique GCs belonging to NGC 4649, a factor of 3.5 larger than previous data sets and with a factor of 3 improvement in velocity precision. We confirm significant GC colour bimodality and find that the red GCs are more centrally concentrated, while the blue GCs are more spatially extended. We infer negative GC colour gradients in the innermost 20 kpc and flat gradients out to large radii. Rotation is detected along the galaxy major axis for all tracers: blue GCs, red GCs, galaxy stars and planetary nebulae. We compare the observed properties of NGC 4649 with galaxy formation models. We find that formation via a major merger between two gas-poor galaxies, followed by satellite accretion, can consistently reproduce the observations of NGC 4649 at different radii. We find no strong evidence to support an interaction between NGC 4649 and the neighbouring spiral galaxy NGC 4647. We identify interesting GC kinematic features in our data, such as counter-rotating subgroups and bumpy kinematic profiles, which encode more clues about the formation history of NGC 4649.

  20. TOWARD PRECISION PHOTOMETRY FOR THE ELT ERA: THE DOUBLE SUBGIANT BRANCH OF NGC 1851 OBSERVED WITH THE GEMINI/GeMS MCAO SYSTEM

    SciTech Connect

    Turri, P.; McConnachie, A. W.; Stetson, P. B.; Andersen, D. R.; Véran, J.-P.; Fiorentino, G.; Bono, G.

    2015-10-01

    The Extremely Large Telescopes currently under construction have a collecting area that is an order of magnitude larger than the present largest optical telescopes. For seeing-limited observations the performance will scale as the collecting area, but with the successful use of adaptive optics (AO), for many applications it will scale as D{sup 4} (where D is the diameter of the primary mirror). Central to the success of the ELTs, therefore, is the successful use of multi-conjugate adaptive optics (MCAO) which applies a high degree of correction over a field of view larger than the few arcseconds that limits classical AO systems. In this Letter, we report on the analysis of crowded field images taken on the central region of the galactic globular cluster NGC 1851 in the K{sub s} band using the Gemini Multi-conjugate Adaptive Optics System (GeMS) at the Gemini South Telescope, the only science-grade MCAO system in operation. We use this cluster as a benchmark to verify the ability to achieve precise near-infrared photometry by presenting the deepest K{sub s} photometry in crowded fields ever obtained from the ground. We construct a color–magnitude diagram in combination with the F606W band from the Hubble Space Telescope/Advanced Camera for Surveys. As well as detecting the “knee” in the lower main sequence at K{sub s} ≃ 20.5, we also detect the double subgiant branch of NGC 1851, which demonstrates the high photometric accuracy of GeMS in crowded fields.

  1. Secondary structural changes in guanidinium hydrochloride denatured mammalian serum albumins and protective effect of small amounts of cationic gemini surfactant pentanediyl-α,ω-bis(cetyldimethylammonium bromide) and methyl-β-cyclodextrin: A spectroscopic study.

    PubMed

    Gull, Nuzhat; Khan, Javed Masood; Ishtikhar, Mohd; Qadeer, Atiyatul; Khan, Rehan Ajmal; Gul, Mudasir; Khan, Rizwan Hasan

    2015-02-01

    In the present study the cationic gemini surfactant assisted refolding of guanidinium hydrochloride (GdCl) denatured mammalian serum albumins viz. sheep serum albumin (SSA), rat serum albumin (RSA) and porcine serum albumin (PSA) using a combination of cationic gemini surfactants, pentanediyl-α,ω-bis(cetyldimethylammonium bromide) (C16H33(CH3)2N(+)-(CH2)5-N(+)(CH3)2C16H33)⋅2Br(-) designated as G5 and methyl-β-cyclodextrin in the artificial chaperone assisted two step method, is attempted. The studies were carried out in an aqueous medium (pH 7.4) using dynamic light scattering (DLS), circular dichroism (CD), and fluorescence spectroscopy. A perusal of DLS data indicates that against the native hydrodynamic radius (Rh) of 4.3nm in SSA, 3.9nm in PSA and 3.5nm in RSA, the Rh of the said proteins, when refolding is attempted by simple dilution, increases to 21.7nm, 36.6nm and 37.2nm, respectively. Hydrodynamic radii very near to the native protein, i.e., 4.0nm, 4.1nm and 4.4nm for RSA, PSA and SSA respectively, is obtained on the sequential addition of G5 and methyl-β-cyclodextrin to the denatured protein. Circular dichroism studies corroborate with the DLS data. The results obtained from the multi-technique approach are ascribed to the presence of two charged head-groups and two hydrocarbon tails in the gemini surfactants resulting in a very strong electrostatic and hydrophobic interactions. Based on the present study it is suggested that the gemini surfactants may be utilized in the protein refolding studies and thus may address one of the most pressing demand of biotechnology industry for the development of efficient and inexpensive folding aides.

  2. Efficient Cellular Knockdown Mediated by siRNA Nanovectors of Gemini Cationic Lipids Having Delocalizable Headgroups and Oligo-Oxyethylene Spacers.

    PubMed

    Martínez-Negro, María; Kumar, Krishan; Barrán-Berdón, Ana L; Datta, Sougata; Kondaiah, Paturu; Junquera, Elena; Bhattacharya, Santanu; Aicart, Emilio

    2016-08-31

    The use of small interfering RNAs (siRNAs) to silence specific genes is one of the most promising approaches in gene therapy, but it requires efficient nanovectors for successful cellular delivery. Recently, we reported liposomal gene carriers derived from a gemini cationic lipid (GCL) of the 1,2-bis(hexadecyl dimethyl imidazolium) oligo-oxyethylene series ((C16Im)2(C2H4O)nC2H4 with n = 1, 2, or 3) and 1,2-dioleyol phosphatidylethanolamine as highly efficient cytofectins for pDNA. On the basis of the satisfactory outcomes of the previous study, the present work focuses on the utility of coliposomes of these gemini lipids with the biocompatible neutral lipid mono oleoyl glycerol (MOG) as highly potent vectors for siRNA cellular transport in the presence of serum. The (C16Im)2(C2H4O)nC2H4/MOG-siRNA lipoplexes were characterized through (i) a physicochemical study (zeta potential, cryo-transmission electron microscopy, small-angle X-ray scattering, and fluorescence anisotropy) to establish the relationship between size, structure, fluidity, and the interaction between siRNA and the GCL/MOG gene vectors and (ii) a biological analysis (flow cytometry, fluorescence microscopy, and cell viability) to report the anti-GFP siRNA transfections in HEK 293T, HeLa, and H1299 cancer cell lines. The in vitro biological analysis confirms the cellular uptake and indicates that a short spacer, a very low molar fraction of GCL in the mixed lipid, and a moderate effective charge ratio of the lipoplex yielded maximum silencing efficacy. At these experimental conditions, the siRNA used in this work is compacted by the GCL/MOG nanovectors by forming two cubic structures (Ia3d and Pm3n) that are correlated with excellent silencing activity. These liposomal nanocarriers possess high silencing activity with a negligible cytotoxicity, which strongly supports their practical use for in vivo knockdown studies.

  3. The Gemini NICI Planet-finding Campaign: Discovery of a Substellar L Dwarf Companion to the Nearby Young M Dwarf CD-35 2722

    NASA Astrophysics Data System (ADS)

    Wahhaj, Zahed; Liu, Michael C.; Biller, Beth A.; Clarke, Fraser; Nielsen, Eric L.; Close, Laird M.; Hayward, Thomas L.; Mamajek, Eric E.; Cushing, Michael; Dupuy, Trent; Tecza, Matthias; Thatte, Niranjan; Chun, Mark; Ftaclas, Christ; Hartung, Markus; Reid, I. Neill; Shkolnik, Evgenya L.; Alencar, Silvia H. P.; Artymowicz, Pawel; Boss, Alan; de Gouveia Dal Pino, Elisabethe; Gregorio-Hetem, Jane; Ida, Shigeru; Kuchner, Marc; Lin, Douglas N. C.; Toomey, Douglas W.

    2011-03-01

    We present the discovery of a wide (67 AU) substellar companion to the nearby (21 pc) young solar-metallicity M1 dwarf CD-35 2722, a member of the ≈100 Myr AB Doradus association. Two epochs of astrometry from the NICI Planet-Finding Campaign confirm that CD-35 2722 B is physically associated with the primary star. Near-IR spectra indicate a spectral type of L4±1 with a moderately low surface gravity, making it one of the coolest young companions found to date. The absorption lines and near-IR continuum shape of CD-35 2722 B agree especially well the dusty field L4.5 dwarf 2MASS J22244381-0158521, while the near-IR colors and absolute magnitudes match those of the 5 Myr old L4 planetary-mass companion, 1RXS J160929.1-210524 b. Overall, CD-35 2722 B appears to be an intermediate-age benchmark for L dwarfs, with a less peaked H-band continuum than the youngest objects and near-IR absorption lines comparable to field objects. We fit Ames-Dusty model atmospheres to the near-IR spectra and find T eff= 1700-1900 K and log(g)= 4.5 ± 0.5. The spectra also show that the radial velocities of components A and B agree to within ±10 km s-1, further confirming their physical association. Using the age and bolometric luminosity of CD-35 2722 B, we derive a mass of 31 ± 8 M Jup from the Lyon/Dusty evolutionary models. Altogether, young late-M to mid-L type companions appear to be overluminous for their near-IR spectral type compared with field objects, in contrast to the underluminosity of young late-L and early-T dwarfs. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ci

  4. THE BOLOCAM GALACTIC PLANE SURVEY. III. CHARACTERIZING PHYSICAL PROPERTIES OF MASSIVE STAR-FORMING REGIONS IN THE GEMINI OB1 MOLECULAR CLOUD

    SciTech Connect

    Dunham, Miranda K.; Evans, Neal J.; Harvey, Paul; Merello, Manuel; Rosolowsky, Erik; Cyganowski, Claudia J.; Aguirre, James; Bally, John; Battersby, Cara; Ginsburg, Adam; Glenn, Jason; Stringfellow, Guy S.; Bradley, Eric Todd; Dowell, Darren; Drosback, Meredith; Schlingman, Wayne; Shirley, Yancy L.; Walawender, Josh; Williams, Jonathan P.

    2010-07-10

    We present the 1.1 mm Bolocam Galactic Plane Survey (BGPS) observations of the Gemini OB1 molecular cloud complex, and targeted NH{sub 3} observations of the BGPS sources. When paired with molecular spectroscopy of a dense gas tracer, millimeter observations yield physical properties such as masses, radii, mean densities, kinetic temperatures, and line widths. We detect 34 distinct BGPS sources above 5{sigma} = 0.37 Jy beam{sup -1} with corresponding 5{sigma} detections in the NH{sub 3}(1,1) transition. Eight of the objects show water maser emission (20%). We find a mean millimeter source FWHM of 1.12 pc and a mean gas kinetic temperature of 20 K for the sample of 34 BGPS sources with detections in the NH{sub 3}(1,1) line. The observed NH{sub 3} line widths are dominated by non-thermal motions, typically found to be a few times the thermal sound speed expected for the derived kinetic temperature. We calculate the mass for each source from the millimeter flux assuming the sources are isothermal and find a mean isothermal mass within a 120'' aperture of 230 {+-} 180 M{sub sun}. We find a total mass of 8400 M{sub sun} for all BGPS sources in the Gemini OB1 molecular cloud, representing 6.5% of the cloud mass. By comparing the millimeter isothermal mass to the virial mass calculated from the NH{sub 3} line widths within a radius equal to the millimeter source size, we find a mean virial parameter (M{sub vir}/M {sub iso}) of 1.0 {+-} 0.9 for the sample. We find mean values for the distributions of column densities of 1.0 x 10{sup 22} cm{sup -2} for H{sub 2}, and 3.0 x 10{sup 14} cm{sup -2} for NH{sub 3}, giving a mean NH{sub 3} abundance of 3.0 x 10{sup -8} relative to H{sub 2}. We find volume-averaged densities on the order of 10{sup 3}-10{sup 4} cm{sup -3}. The sizes and densities suggest that in the Gem OB1 region the BGPS is detecting the clumps from which stellar clusters form, rather than smaller, higher density cores where single stars or small multiple systems

  5. THE GEMINI NICI PLANET-FINDING CAMPAIGN: DISCOVERY OF A CLOSE SUBSTELLAR COMPANION TO THE YOUNG DEBRIS DISK STAR PZ Tel

    SciTech Connect

    Biller, Beth A.; Liu, Michael C.; Wahhaj, Zahed; Dupuy, Trent J.; Ftaclas, Christ; Nielsen, Eric L.; Close, Laird M.; Males, Jared; Skemer, Andrew; Hayward, Thomas L.; Hartung, Markus; Chun, Mark; Clarke, Fraser; Tecza, Matthias; Thatte, Niranjan; Reid, I. Neill; Shkolnik, Evgenya L.; Alencar, Silvia H. P.; Artymowicz, Pawel

    2010-09-01

    We report the discovery of a tight substellar companion to the young solar analog PZ Tel, a member of the {beta} Pic moving group observed with high-contrast adaptive optics imaging as part of the Gemini Near-Infrared Coronagraphic Imager Planet-Finding Campaign. The companion was detected at a projected separation of 16.4 {+-} 1.0 AU (0.''33 {+-} 0.''01) in 2009 April. Second-epoch observations in 2010 May demonstrate that the companion is physically associated and shows significant orbital motion. Monte Carlo modeling constrains the orbit of PZ Tel B to eccentricities >0.6. The near-IR colors of PZ Tel B indicate a spectral type of M7 {+-} 2 and thus this object will be a new benchmark companion for studies of ultracool, low-gravity photospheres. Adopting an age of 12{sup +8} {sub -4} Myr for the system, we estimate a mass of 36 {+-} 6 M {sub Jup} based on the Lyon/DUSTY evolutionary models. PZ Tel B is one of the few young substellar companions directly imaged at orbital separations similar to those of giant planets in our own solar system. Additionally, the primary star PZ Tel A shows a 70 {mu}m emission excess, evidence for a significant quantity of circumstellar dust that has not been disrupted by the orbital motion of the companion.

  6. Interaction of bovine serum albumin (BSA) with novel gemini surfactants studied by synchrotron radiation scattering (SR-SAXS), circular dichroism (CD), and nuclear magnetic resonance (NMR).

    PubMed

    Gospodarczyk, W; Szutkowski, K; Kozak, M

    2014-07-24

    The interaction of three dicationic (gemini) surfactants-3,3'-[1,6-(2,5-dioxahexane)]bis(1-dodecylimidazolium) chloride (oxyC2), 3,3'-[1,16-(2,15-dioxahexadecane)]bis(1-dodecylimidazolium) chloride (oxyC12), and 1,4-bis(butane)imidazole-1-yl-3-dodecylimidazolium chloride (C4)--with bovine serum albumin (BSA) has been studied by the use of small-angle X-ray scattering (SAXS), circular dichroism (CD), and (1)H nuclear magnetic resonance diffusometry. The results of CD studies show that the conformation of BSA was changed dramatically in the presence of all studied surfactants. The greater decrease (from 56 to 24%) in the α-helical structure of BSA was observed for oxyC2 surfactant. The radii of gyration estimated from SAXS data varied between 3 and 26 nm for the BSA/oxyC2 and BSA/oxyC12 systems. The hydrodynamic radius of the BSA/surfactant system estimated from NMR diffusometry varies between 5 and 11 nm for BSA/oxyC2 and 5 and 8 nm for BSA/oxyC12.

  7. Global near-IR maps from Gemini-N and Keck in 2010, with a special focus on Janus Patera and Kanehekili Fluctus

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Davies, Ashley Gerard; McGregor, Alistair; Trujillo, Chad; Ádámkovics, Máté; Veeder, Glenn J.; Matson, Dennis L.; Leone, Giovanni

    2014-11-01

    We have imaged Io in the near-infrared (1-5 μm) with adaptive optics on the 10-m W.M. Keck II and the Gemini North telescopes. We have constructed global maps from the data taken in 2010. Although numerous hot spots are visible, the maps are dominated by two volcanic centers: Loki Patera and Kanehekili Fluctus. We have examined in detail the thermal emission from Janus Patera and Kanehekili Fluctus using images obtained between 2003 and 2010, and have created a timeline of volcanic activity at these locations utilizing data from a wide variety of sources. Based on our data and this timeline we find that the thermal emission from Janus Patera is relatively steady, indicative of an active lava lake. The thermal emission from Kanehekili Fluctus, however, is quite variable, and is indicative of the emplacement of extensive lava flows. In 2010, the thermal emission from this location was ∼10 times higher than ever seen before, indicative of a particularly voluminous eruption of lava.

  8. POLARIZED LIGHT IMAGING OF THE HD 142527 TRANSITION DISK WITH THE GEMINI PLANET IMAGER: DUST AROUND THE CLOSE-IN COMPANION

    SciTech Connect

    Rodigas, Timothy J.; Weinberger, Alycia; Follette, Katherine B.; Close, Laird; Hines, Dean C.

    2014-08-20

    When giant planets form, they grow by accreting gas and dust. HD 142527 is a young star that offers a scaled-up view of this process. It has a broad, asymmetric ring of gas and dust beyond ∼100 AU and a wide inner gap. Within the gap, a low-mass stellar companion orbits the primary star at just ∼12 AU, and both the primary and secondary are accreting gas. In an attempt to directly detect the dusty counterpart to this accreted gas, we have observed HD 142527 with the Gemini Planet Imager in polarized light at Y band (0.95-1.14 μm). We clearly detect the companion in total intensity and show that its position and photometry are generally consistent with the expected values. We also detect a point source in polarized light that may be spatially separated by ∼ a few AU from the location of the companion in total intensity. This suggests that dust is likely falling onto or orbiting the companion. Given the possible contribution of scattered light from this dust to previously reported photometry of the companion, the current mass limits should be viewed as upper limits only. If the dust near the companion is eventually confirmed to be spatially separated, this system would resemble a scaled-up version of the young planetary system inside the gap of the transition disk around LkCa 15.

  9. Caracterización del entorno del los blazares PG1553+113 y 3C66A con datos GEMINI-GMOS en las bandas g' e i'

    NASA Astrophysics Data System (ADS)

    Torres Zafra, J.; Cellone, S. A.; Andruchow, I.

    The blazars PG1553+113 and 3C66A have been recently detected at TeV energies -rays; however; an accurate modelling of their electromagnetic emission as well as -ray absorption by the extragalactic background light (EBL) are prevented by their lack of firm redshift determinations. This is due to the fact that; being objects of the BLLac subclass; their optical spectral have by definition very faint emission lines. In this paper the environment of both objects is photometrically analyzed; looking for overdensities that may trace galaxy clusters. Comparing magnitudes and colors of detected object to those of model galaxies allows us to provide a new constraint to the redshifts of both blazars. FULL TEXT IN SPANISH

  10. Time variability of Neptune's horizontal and vertical cloud structure revealed by VLT/SINFONI and Gemini/NIFS from 2009 to 2013

    NASA Astrophysics Data System (ADS)

    Irwin, P. G. J.; Fletcher, L. N.; Tice, D.; Owen, S. J.; Orton, G. S.; Teanby, N. A.; Davis, G. R.

    2016-06-01

    New observations of Neptune's clouds in the near infrared were acquired in October 2013 with SINFONI on ESO's Very Large Telescope (VLT) in Chile. SINFONI is an Integral Field Unit spectrometer returning a 64 × 64 pixel image with 2048 wavelengths. Image cubes in the J-band (1.09-1.41 μm) and H-band (1.43-1.87 μm) were obtained at spatial resolutions of 0.1″and 0.025″per pixel, while SINFONI's adaptive optics provided an effective resolution of approximately 0.1″. Image cubes were obtained at the start and end of three successive nights to monitor the temporal development of discrete clouds both at short timescales (i.e. during a single night) as well as over the longer period of the three-day observing run. These observations were compared with similar H-band observations obtained in September 2009 with the NIFS Integral Field Unit spectrometer on the Gemini-North telescope in Hawaii, previously reported by Irwin et al. (2011) [Icarus, 216, 141-158], and previously unreported Gemini/NIFS observations at lower spatial resolution made in 2011. We find both similarities and differences between these observations, spaced over four years. The same overall cloud structure is seen with high, bright clouds visible at mid-latitudes (30-40°N,S), with slightly lower clouds observed at lower latitudes, together with small discrete clouds seen circling the pole at a latitude of approximately 60°S. However, while discrete clouds were visible at this latitude at both the main cloud deck level (at 2-3 bar) and in the upper troposphere (100-500 mb) in 2009, no distinct deep (2-3 bar), discrete circumpolar clouds were visible in 2013, although some deep clouds were seen at the southern edge of the main cloud belt at 30-40°S, which have not been observed before. The nature of the deep sub-polar discrete clouds observed in 2009 is intriguing. While it is possible that in 2013 these deeper clouds were masked by faster moving, overlying features, we consider that it is

  11. Probing the vertical cloud structure of Uranus and Neptune with ground-based near-infrared observations at UKIRT, IRTF and Gemini-North

    NASA Astrophysics Data System (ADS)

    Irwin, Patrick G. J.; Teanby, Nicholas N.; Davis, Gary R.; Orton, Glenn; Fletcher, Leigh; Tice, Dane; Hurley, Jane

    2010-05-01

    and discussed. Observations of both Uranus and Neptune were also made in 2009 with the SpeX instrument (0.8 to 2.4 μm) on the NASA Infrared Telescope Facility and also with the NIFS and NIRI instruments on the Gemini North telescope. The IRTF measurements were made with seeing conditions of approximately 0.5 arcsec, while the Gemini observations were made with Adaptive Optics and thus have considerably better spatial resolution. We intend to use the NIFS observations to study the limb-darkening curves from 1.45 to 1.75 μm, which should provide better constraints in the vertical cloud structure and we intend to use the IRTF measurements to extend our analysis to shorter wavelengths and also provide better radiometric calibration between the different reflectance peaks. These new observations will be presented and compared with the previous UKIRT observations.

  12. How does the spacer length of cationic gemini lipids influence the lipoplex formation with plasmid DNA? Physicochemical and biochemical characterizations and their relevance in gene therapy.

    PubMed

    Muñoz-Úbeda, Mónica; Misra, Santosh K; Barrán-Berdón, Ana L; Datta, Sougata; Aicart-Ramos, Clara; Castro-Hartmann, Pablo; Kondaiah, Paturu; Junquera, Elena; Bhattacharya, Santanu; Aicart, Emilio

    2012-12-10

    Lipoplexes formed by the pEGFP-C3 plasmid DNA (pDNA) and lipid mixtures containing cationic gemini surfactant of the 1,2-bis(hexadecyl dimethyl ammonium) alkanes family referred to as C16CnC16, where n=2, 3, 5, or 12, and the zwitterionic helper lipid, 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) have been studied from a wide variety of physical, chemical, and biological standpoints. The study has been carried out using several experimental methods, such as zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), cryo-TEM, gene transfection, cell viability/cytotoxicity, and confocal fluorescence microscopy. As reported recently in a communication (J. Am. Chem. Soc. 2011, 133, 18014), the detailed physicochemical and biological studies confirm that, in the presence of the studied series lipid mixtures, plasmid DNA is compacted with a large number of its associated Na+ counterions. This in turn yields a much lower effective negative charge, qpDNA−, a value that has been experimentally obtained for each mixed lipid mixture. Consequently, the cationic lipid (CL) complexes prepared with pDNA and CL/DOPE mixtures to be used in gene transfection require significantly less amount of CL than the one estimated assuming a value of qDNA−=−2. This drives to a considerably lower cytotoxicity of the gene vector. Depending on the CL molar composition, α, of the lipid mixture, and the effective charge ratio of the lipoplex, ρeff, the reported SAXS data indicate the presence of two or three structures in the same lipoplex, one in the DOPE-rich region, other in the CL-rich region, and another one present at any CL composition. Cryo-TEMand SAXS studies with C16CnC16/DOPE-pDNA lipoplexes indicate that pDNA is localized between the mixed lipid bilayers of lamellar structures within a monolayer of ∼2 nm. This is consistent with a highly compacted supercoiled pDNA conformation compared with that of linear DNA. Transfection studies were carried out

  13. THE GEMINI/HST CLUSTER PROJECT: STRUCTURAL AND PHOTOMETRIC PROPERTIES OF GALAXIES IN THREE z = 0.28-0.89 CLUSTERS

    SciTech Connect

    Chiboucas, Kristin; Joergensen, Inger; Barr, Jordi; Collobert, Maela; Davies, Roger; Flint, Kathleen E-mail: ijorgensen@gemini.edu E-mail: maela.collobert@gmail.com E-mail: kflint@nationalpostdoc.org

    2009-10-01

    We present the data processing and analysis techniques we are using to determine the structural and photometric properties of galaxies in our Gemini/HST Galaxy Cluster Project sample. The goal of this study is to understand cluster galaxy evolution in terms of scaling relations and structural properties of cluster galaxies at redshifts 0.15 < z < 1.0. To derive parameters such as total magnitude, half-light radius, effective surface brightness, and Sersic n, we fit r {sup 1/4} law and Sersic function two-dimensional surface brightness profiles to each of the galaxies in our sample. Using simulated galaxies, we test how the assumed profile affects the derived parameters and how the uncertainties affect our Fundamental Plane results. We find that while fitting galaxies that have Sersic index n < 4 with r {sup 1/4} law profiles systematically overestimates the galaxy radius and flux, the combination of profile parameters that enter the Fundamental Plane has uncertainties that are small. Average systematic offsets and associated random uncertainties in magnitude and log r{sub e} for n>2 galaxies fitted with r {sup 1/4} law profiles are -0.1 {+-} 0.3 and 0.1 {+-} 0.2, respectively. The combination of effective radius and surface brightness, log r{sub e} - {beta}log (I) {sub e}, that enters the Fundamental Plane produces offsets smaller than -0.02 {+-} 0.10. This systematic error is insignificant and independent of galaxy magnitude or size. A catalog of photometry and surface brightness profile parameters is presented for three of the clusters in our sample, RX J0142.0+2131, RX J0152.7-1357, and RX J1226.9+3332 at redshifts 0.28, 0.83, and 0.89, respectively.

  14. The Next Generation Virgo Cluster Survey. XII. Stellar Populations and Kinematics of Compact, Low-mass Early-type Galaxies from Gemini GMOS-IFU Spectroscopy

    NASA Astrophysics Data System (ADS)

    Guérou, Adrien; Emsellem, Eric; McDermid, Richard M.; Côté, Patrick; Ferrarese, Laura; Blakeslee, John P.; Durrell, Patrick R.; MacArthur, Lauren A.; Peng, Eric W.; Cuillandre, Jean-Charles; Gwyn, Stephen

    2015-05-01

    We present Gemini Multi Object Spectrograph integral-field unit (GMOS-IFU) data of eight compact, low-mass early-type galaxies (ETGs) in the Virgo cluster. We analyze their stellar kinematics and stellar population and present two-dimensional maps of these properties covering the central 5″ × 7″ region. We find a large variety of kinematics, from nonrotating to highly rotating objects, often associated with underlying disky isophotes revealed by deep images from the Next Generation Virgo Cluster Survey. In half of our objects, we find a centrally concentrated younger and more metal-rich stellar population. We analyze the specific stellar angular momentum through the λR parameter and find six fast rotators and two slow rotators, one having a thin counterrotating disk. We compare the local galaxy density and stellar populations of our objects with those of 39 more extended low-mass Virgo ETGs from the SMAKCED survey and 260 massive (M > 1010 {{M}⊙ }) ETGs from the ATLAS3D sample. The compact low-mass ETGs in our sample are located in high-density regions, often close to a massive galaxy, and have, on average, older and more metal-rich stellar populations than less compact low-mass galaxies. We find that the stellar population parameters follow lines of constant velocity dispersion in the mass-size plane, smoothly extending the comparable trends found for massive ETGs. Our study supports a scenario where low-mass compact ETGs have experienced long-lived interactions with their environment, including ram-pressure stripping and gravitational tidal forces, that may be responsible for their compact nature.

  15. Polarized Disk Emission from Herbig Ae/Be Stars Observed Using Gemini Planet Imager: HD 144432, HD 150193, HD 163296, and HD 169142

    NASA Astrophysics Data System (ADS)

    Monnier, John D.; Harries, Tim J.; Aarnio, Alicia; Adams, Fred C.; Andrews, Sean; Calvet, Nuria; Espaillat, Catherine; Hartmann, Lee; Hinkley, Sasha; Kraus, Stefan; McClure, Melissa; Oppenheimer, Rebecca; Perrin, Marshall; Wilner, David

    2017-03-01

    In order to look for signs of ongoing planet formation in young disks, we carried out the first J-band polarized emission imaging of the Herbig Ae/Be stars HD 150193, HD 163296, and HD 169142 using the Gemini Planet Imager, along with new H band observations of HD 144432. We confirm the complex “double ring” structure for the nearly face-on system HD 169142 first seen in H-band, finding the outer ring to be substantially redder than the inner one in polarized intensity. Using radiative transfer modeling, we developed a physical model that explains the full spectral energy distribution and J- and H-band surface brightness profiles, suggesting that the differential color of the two rings could come from reddened starlight traversing the inner wall and may not require differences in grain properties. In addition, we clearly detect an elongated, off-center ring in HD 163296 (MWC 275), locating the scattering surface to be 18 au above the midplane at a radial distance of 77 au, co-spatial with a ring seen at 1.3 mm by ALMA linked to the CO snow line. Lastly, we report a weak tentative detection of scattered light for HD 150193 (MWC 863) and a non-detection for HD 144432 the stellar companion known for each of these targets has likely disrupted the material in the outer disk of the primary star. For HD 163296 and HD 169142, the prominent outer rings we detect could be evidence for giant planet formation in the outer disk or a manifestation of large-scale dust growth processes possibly related to snow-line chemistry.

  16. 1 to 2.4 microns spectrum and orbital properties of the Giant Planet Beta Pictoris b obtained with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Pueyo, Laurent; Chilcote, Jeffrey; Millar-Blanchaer, Max; Barman, Travis; Fitzgerald, Michael P.; Graham, James R.; Larkin, James; Kalas, Paul G.; dawson, Rebekah; Wang, Jason; Perrin, Marshall; Moon, Dae-Sik; Macintosh, Bruce

    2015-12-01

    We present a low-resolution multi-band spectrum of the planetary companion to the nearby young star beta Pictoris using the Gemini Planet Imager (GPI). GPI is designed to image and provide low-resolution spectra of Jupiter sized, self-luminous planetary companions around young nearby stars. While H-bandis the primary workhorse for the GPI Exoplanet Survey, the instrument is capable of observing in the near infrared covering Y, J, H, and K bands. These observations of Beta Pic Pictoris b were taken covering multiple bands as part of GPI’s verification and commissioning phase in 2013 and 2014. Using atmospheric models along with the H-band data we recently reported an effective temperature of 1600-1700 K and a surface gravity of log (g) = 3.5-4.5 (cgs units). A similar exercise was also carried out by an independent team using the J band data, and did yield similar conclusions. These values agree well with ”hot-start” predictions from planetary evolution models for a gas giant with mass between 10 and 12 M Jup and age between 10 and 20 Myr. Here we revisit these conclusions in light of a joint analysis of these two datasets along with the longer wavelength GPI spectrum in K band, and present refined constraints on the atmospheric properties of this giant planet. In addition, we present an updated orbit for Beta Pictoris b based on astrometric measurements taken using commissioning and subsequent monitoring observations, spanning 14 months. The planet has a semi-major axis of 9.2 (+1.5 -0.4) AU, with an eccentricity e≤ 0.26. The position angle of the ascending node is Ω=31.75 deg±0.15, offset from both the outer main disk and the inner disk seen in the GPI image. We finally discuss these properties in the context of planet-disk dynamical interactions.

  17. The stellar mass-size relation for cluster galaxies at z = 1 with high angular resolution from the Gemini/GeMS multiconjugate adaptive optics system

    NASA Astrophysics Data System (ADS)

    Sweet, Sarah M.; Sharp, Robert; Glazebrook, Karl; Rigaut, Francois; Carrasco, Eleazar R.; Brodwin, Mark; Bayliss, Matthew; Stalder, Brian; Abraham, Roberto; McGregor, Peter

    2017-01-01

    We present the stellar mass-size relation for 49 galaxies within the z = 1.067 cluster SPT-CL J0546-5345, with full width at half-maximum ˜80-120 mas Ks-band data from the Gemini multiconjugate adaptive optics system (GeMS/GSAOI). This is the first such measurement in a cluster environment, performed at sub-kpc resolution at rest-frame wavelengths dominated by the light of the underlying old stellar populations. The observed stellar mass-size relation is offset from the local relation by 0.21 dex, corresponding to a size evolution proportional to (1 + z)-1.25, consistent with the literature. The slope of the stellar mass-size relation β = 0.74 ± 0.06, consistent with the local relation. The absence of slope evolution indicates that the amount of size growth is constant with stellar mass. This suggests that galaxies in massive clusters such as SPT-CL J0546-5345 grow via processes that increase the size without significant morphological interference, such as minor mergers and/or adiabatic expansion. The slope of the cluster stellar mass-size relation is significantly shallower if measured in Hubble Space Telescope (HST)/Advanced Camera for Surveys imaging at wavelengths blueward of the Balmer break, similar to rest-frame ultraviolet relations at z = 1 in the literature. The stellar mass-size relation must be measured at redder wavelengths, which are more sensitive to the old stellar population that dominates the stellar mass of the galaxies. The slope is unchanged when GeMS Ks-band imaging is degraded to the resolution of K-band HST/Near Infrared Camera and Multi-Object Spectrometer resolution but dramatically affected when degraded to Ks-band Magellan/FourStar resolution. Such measurements must be made with adaptive optics in order to accurately characterize the sizes of compact, z = 1 galaxies.

  18. A multi-wavelength study of the 2009 impact on Jupiter: Comparison of high resolution images from Gemini, Keck and HST

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Fletcher, Leigh N.; Pérez-Hoyos, Santiago; Hammel, Heidi B.; Orton, Glenn S.; Wong, Michael H.; Luszcz-Cook, Statia; Sánchez-Lavega, Agustin; Boslough, Mark

    2010-12-01

    Within several days of A. Wesley's announcement that Jupiter was hit by an object on UT 19 July 2009, we observed the impact site with (1) the Hubble Space Telescope (HST) at UV through visible (225-924 nm) wavelengths, (2) the 10-m W.M. Keck II telescope in the near-infrared (1-5 μm), and (3) the 8-m Gemini-North telescope in the mid-infrared (7.7-18 μm). All observations reported here were obtained between 22 and 25 July 2009. Observations at visible and near-infrared wavelengths show that large (˜0.75-μm radius) dark (imaginary index of refraction mi ˜ 0.01-0.1) particulates were deposited at atmospheric pressures between 10 and 200-300 mbar; analysis of HST-UV data reveals that in addition smaller-sized (˜0.1 μm radius) material must have been deposited at the highest altitudes (˜10 mbar). Differences in morphology between the UV and visible/near-IR images suggest three-dimensional variations in particle size and density across the impact site, which probably were induced during the explosion and associated events. At mid-infrared wavelengths the brightness temperature increased due to both an enhancement in the stratospheric NH 3 gas abundance and the physical temperature of the atmosphere. This high brightness temperature coincides with the center part of the impact site as seen with HST. This observation, combined with (published) numerical simulations of the Shoemaker-Levy 9 impacts on Jupiter and the Tunguska airburst on Earth, suggests that the downward jet from the terminal explosion probably penetrated down to the ˜700-mbar level.

  19. RECOVERY OF THE CANDIDATE PROTOPLANET HD 100546 b WITH GEMINI/NICI AND DETECTION OF ADDITIONAL (PLANET-INDUCED?) DISK STRUCTURE AT SMALL SEPARATIONS

    SciTech Connect

    Currie, Thayne; Kudo, Tomoyuki; Muto, Takayuki; Honda, Mitsuhiko; Brandt, Timothy D.; Grady, Carol; Fukagawa, Misato; Burrows, Adam; Janson, Markus; Kuzuhara, Masayuki; McElwain, Michael W.; Follette, Katherine; Hashimoto, Jun; Henning, Thomas; Kandori, Ryo; Kusakabe, Nobuhiko; Morino, Jun-ichi; Nishikawa, Jun; Kwon, Jungmi; Mede, Kyle; and others

    2014-12-01

    We report the first independent, second epoch (re-)detection of a directly imaged protoplanet candidate. Using L' high-contrast imaging of HD 100546 taken with the Near-Infrared Coronagraph and Imager on Gemini South, we recover ''HD 100546 b'' with a position and brightness consistent with the original Very Large Telescope/NAos-COnica detection from Quanz et al., although data obtained after 2013 will be required to decisively demonstrate common proper motion. HD 100546 b may be spatially resolved, up to ≈12-13 AU in diameter, and is embedded in a finger of thermal IR-bright, polarized emission extending inward to at least 0.''3. Standard hot-start models imply a mass of ≈15 M{sub J} . However, if HD 100546 b is newly formed or made visible by a circumplanetary disk, both of which are plausible, its mass is significantly lower (e.g., 1-7 M{sub J} ). Additionally, we discover a thermal IR-bright disk feature, possibly a spiral density wave, at roughly the same angular separation as HD 100546 b but 90° away. Our interpretation of this feature as a spiral arm is not decisive, but modeling analyses using spiral density wave theory implies a wave launching point exterior to ≈0.''45 embedded within the visible disk structure: plausibly evidence for a second, hitherto unseen, wide-separation planet. With one confirmed protoplanet candidate and evidence for one to two others, HD 100546 is an important evolutionary precursor to intermediate-mass stars with multiple super-Jovian planets at moderate/wide separations like HR 8799.

  20. Gemini long-slit observations of luminous obscured quasars: Further evidence for an upper limit on the size of the narrow-line region

    SciTech Connect

    Hainline, Kevin N.; Hickox, Ryan C.; Greene, Jenny E.; Myers, Adam D.; Zakamska, Nadia L.; Liu, Guilin; Liu, Xin

    2014-05-20

    We examine the spatial extent of the narrow-line regions (NLRs) of a sample of 30 luminous obscured quasars at 0.4 < z < 0.7 observed with spatially resolved Gemini-N GMOS long-slit spectroscopy. Using the [O III] λ5007 emission feature, we estimate the size of the NLR using a cosmology-independent measurement: the radius where the surface brightness falls to 10{sup –15} erg s{sup –1} cm{sup –2} arcsec{sup –2}. We then explore the effects of atmospheric seeing on NLR size measurements and conclude that direct measurements of the NLR size from observed profiles are too large by 0.1-0.2 dex on average, as compared to measurements made to best-fit Sérsic or Voigt profiles convolved with the seeing. These data, which span a full order of magnitude in IR luminosity (log (L {sub 8} {sub μm}/erg s{sup –1}) = 44.4-45.4), also provide strong evidence that there is a flattening of the relationship between NLR size and active galactic nucleus luminosity at a seeing-corrected size of ∼7 kpc. The objects in this sample have high luminosities which place them in a previously under-explored portion of the size-luminosity relationship. These results support the existence of a maximal size of the NLR around luminous quasars; beyond this size, there is either not enough gas or the gas is over-ionized and does not produce enough [O III] λ5007 emission.