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Sample records for conformable flexible large-area

  1. Conformable, flexible, large-area networks of pressure and thermal sensors with organic transistor active matrixes

    NASA Astrophysics Data System (ADS)

    Someya, Takao; Kato, Yusaku; Sekitani, Tsuyoshi; Iba, Shingo; Noguchi, Yoshiaki; Murase, Yousuke; Kawaguchi, Hiroshi; Sakurai, Takayasu

    2005-08-01

    Skin-like sensitivity, or the capability to recognize tactile information, will be an essential feature of future generations of robots, enabling them to operate in unstructured environments. Recently developed large-area pressure sensors made with organic transistors have been proposed for electronic artificial skin (E-skin) applications. These sensors are bendable down to a 2-mm radius, a size that is sufficiently small for the fabrication of human-sized robot fingers. Natural human skin, however, is far more complex than the transistor-based imitations demonstrated so far. It performs other functions, including thermal sensing. Furthermore, without conformability, the application of E-skin on three-dimensional surfaces is impossible. In this work, we have successfully developed conformable, flexible, large-area networks of thermal and pressure sensors based on an organic semiconductor. A plastic film with organic transistor-based electronic circuits is processed to form a net-shaped structure, which allows the E-skin films to be extended by 25%. The net-shaped pressure sensor matrix was attached to the surface of an egg, and pressure images were successfully obtained in this configuration. Then, a similar network of thermal sensors was developed with organic semiconductors. Next, the possible implementation of both pressure and thermal sensors on the surfaces is presented, and, by means of laminated sensor networks, the distributions of pressure and temperature are simultaneously obtained. Author contributions: T. Someya designed research; T. Someya, Y.K., T. Sekitani, S.I., Y.N., Y.M., H.K., and T. Sakurai performed research; and T. Someya wrote the paper.This paper was submitted directly (Track II) to the PNAS office.Freely available online through the PNAS open access option.Abbreviations: E-skin, electronic artificial skin; IDS, source-drain current; PTCDI, 3,4,9,10-perylene-tetracarboxylic-diimide; parylene, polychloro-para-xylylene; CuPc, copper

  2. Highly conformal SiO2/Al2O3 nanolaminate gas-diffusion barriers for large-area flexible electronics applications

    NASA Astrophysics Data System (ADS)

    Choi, Jin-Hwan; Kim, Young-Min; Park, Young-Wook; Park, Tae-Hyun; Jeong, Jin-Wook; Choi, Hyun-Ju; Song, Eun-Ho; Lee, Jin-Woo; Kim, Cheol-Ho; Ju, Byeong-Kwon

    2010-11-01

    The present study demonstrates a flexible gas-diffusion barrier film, containing an SiO2/Al2O3 nanolaminate on a plastic substrate. Highly uniform and conformal coatings can be made by alternating the exposure of a flexible polyethersulfone surface to vapors of SiO2 and Al2O3, at nanoscale thickness cycles via RF-magnetron sputtering deposition. The calcium degradation test indicates that 24 cycles of a 10/10 nm inorganic bilayer, top-coated by UV-cured resin, greatly enhance the barrier performance, with a permeation rate of 3.79 × 10 - 5 g m - 2 day - 1 based on the change in the ohmic behavior of the calcium sensor at 20 °C and 50% relative humidity. Also, the permeation rate for 30 cycles of an 8/8 nm inorganic bilayer coated with UV resin was beyond the limited measurable range of the Ca test at 60 °C and 95% relative humidity. It has been found that such laminate films can effectively suppress the void defects of a single inorganic layer, and are significantly less sensitive against moisture permeation. This nanostructure, fabricated by an RF-sputtering process at room temperature, is verified as being useful for highly water-sensitive organic electronics fabricated on plastic substrates.

  3. Large area flexible solar array design for Space Shuttle application

    NASA Technical Reports Server (NTRS)

    Souza, C. J.

    1980-01-01

    A large area flexible solar array has been designed for Shuttle power augmentation. The solar array utilizes large area, low cost, weldable solar cells. The paper addresses how the unique requirements of this system are implemented into the design. Economic and reliability issues relating to the optimization of a large area, foldable solar array concomitant to the Shuttle/Orbiter system are reviewed.

  4. Gravure printing of graphene for large-area flexible electronics.

    PubMed

    Secor, Ethan B; Lim, Sooman; Zhang, Heng; Frisbie, C Daniel; Francis, Lorraine F; Hersam, Mark C

    2014-07-01

    Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large-area printed and flexible electronics.

  5. Semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  6. Flexible and mechanical strain resistant large area SERS active substrates

    NASA Astrophysics Data System (ADS)

    Singh, J. P.; Chu, Hsiaoyun; Abell, Justin; Tripp, Ralph A.; Zhao, Yiping

    2012-05-01

    We report a cost effective and facile way to synthesize flexible, uniform, and large area surface enhanced Raman scattering (SERS) substrates using an oblique angle deposition (OAD) technique. The flexible SERS substrates consist of 1 μm long, tilted silver nanocolumnar films deposited on flexible polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET) sheets using OAD. The SERS enhancement activity of these flexible substrates was determined using 10-5 M trans-1,2-bis(4-pyridyl) ethylene (BPE) Raman probe molecules. The in situ SERS measurements on these flexible substrates under mechanical (tensile/bending) strain conditions were performed. Our results show that flexible SERS substrates can withstand a tensile strain (ε) value as high as 30% without losing SERS performance, whereas the similar bending strain decreases the SERS performance by about 13%. A cyclic tensile loading test on flexible PDMS SERS substrates at a pre-specified tensile strain (ε) value of 10% shows that the SERS intensity remains almost constant for more than 100 cycles. These disposable and flexible SERS substrates can be integrated with biological substances and offer a novel and practical method to facilitate biosensing applications.

  7. Large area flexible SERS active substrates using engineered nanostructures

    NASA Astrophysics Data System (ADS)

    Chung, Aram J.; Huh, Yun Suk; Erickson, David

    2011-07-01

    Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as clothing. We demonstrate the formation of four different types of nanostructure arrays (pillar, nib, ellipsoidal cylinder, and triangular tip) by controlling the evaporation angle, substrate rotation, and deposition rate of metals onto anodized alumina nanoporous membranes as large as 27 mm. In addition, we present experimental results showing how a hybrid structure comprising of gold nanospheres embedded in a silver nano-pillar structure can be used to obtain a 50× SERS enhancement over the raw nanoparticles themselves.Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as

  8. Large area flexible SERS active substrates using engineered nanostructures.

    PubMed

    Chung, Aram J; Huh, Yun Suk; Erickson, David

    2011-07-01

    Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as clothing. We demonstrate the formation of four different types of nanostructure arrays (pillar, nib, ellipsoidal cylinder, and triangular tip) by controlling the evaporation angle, substrate rotation, and deposition rate of metals onto anodized alumina nanoporous membranes as large as 27 mm. In addition, we present experimental results showing how a hybrid structure comprising of gold nanospheres embedded in a silver nano-pillar structure can be used to obtain a 50× SERS enhancement over the raw nanoparticles themselves.

  9. Fabrication of large area flexible PDMS waveguide sheets

    NASA Astrophysics Data System (ADS)

    Green, Robert; Knopf, George K.; Bordatchev, Evgueni

    2016-03-01

    Soft-lithography techniques can be used to fabricate mechanically flexible polydimethylsiloxane (PDMS) optical waveguide sheets that act as large area light collectors (concentrators) and illuminators (diffusers). The performance and efficiency of these optical sheets is determined by the position and geometry of micro-optical features embedded in the sheet or imprinted on its surface, thickness and shape of the waveguide, core and cladding refractive indices, and wavelength of the incident light source. The critical design-for-manufacturability parameters are discussed and a scalable method of fabricating multi-layered PDMS optical waveguides is introduced. To illustrate the concepts a prototype waveguide sheet that acts a combined light collector and illumination panel is fabricated and tested. The region of the waveguide sheet that acts as the light collector consists of two superimposed PDMS layers with slightly different indices of refraction. The top layer is patterned with micro-lenses that focus the incident light rays onto the micro-wedge features that act as reflectors on the bottom of the second layer and, due to total internal reflection, redirect the light rays to the light diffuser region of the waveguide sheet. The bottom face of the diffuser PDMS layer is patterned with angled triangular wedge micro-features that project the light out of the waveguide sheet forming an illuminating pattern. The proposed fabrication technique utilizes precision machined polymethylmethacrylate (PMMA) moulds with negative patterned PDMS inserts that transfer the desired micro-optical features onto the moulded waveguide.

  10. Conformational flexibility of aspartame.

    PubMed

    Toniolo, Claudio; Temussi, Pierandrea

    2016-05-01

    L-Aspartyl-L-phenylalanine methyl ester, better known as aspartame, is not only one of the most used artificial sweeteners, but also a very interesting molecule with respect to the correlation between molecular structure and taste. The extreme conformational flexibility of this dipeptide posed a huge difficulty when researchers tried to use it as a lead compound to design new sweeteners. In particular, it was difficult to take advantage of its molecular model as a mold to infer the shape of the, then unknown, active site of the sweet taste receptor. Here, we follow the story of the 3D structural aspects of aspartame from early conformational studies to recent docking into homology models of the receptor. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 376-384, 2016. PMID:27038223

  11. Conformational flexibility of aspartame.

    PubMed

    Toniolo, Claudio; Temussi, Pierandrea

    2016-05-01

    L-Aspartyl-L-phenylalanine methyl ester, better known as aspartame, is not only one of the most used artificial sweeteners, but also a very interesting molecule with respect to the correlation between molecular structure and taste. The extreme conformational flexibility of this dipeptide posed a huge difficulty when researchers tried to use it as a lead compound to design new sweeteners. In particular, it was difficult to take advantage of its molecular model as a mold to infer the shape of the, then unknown, active site of the sweet taste receptor. Here, we follow the story of the 3D structural aspects of aspartame from early conformational studies to recent docking into homology models of the receptor. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 376-384, 2016.

  12. Site-specific stamping of graphene micro-patterns over large areas using flexible stamps.

    PubMed

    Chen, Chun-Hu; Reddy, Kongara M; Padture, Nitin P

    2012-06-15

    Site-specific stamping has the potential of becoming a low-cost, high-throughput method for depositing specific-shaped graphene micro-patterns over large areas on a wide variety of substrates. The use of an approach involving flexible stamps presented here represents an important advance towards reaching that potential. This approach entails lithographic creation (dry etching) of high-quality micro-pillar arrays of highly oriented pyrolytic graphite (HOPG) over large areas. This is followed by embedding the micro-pillar arrays in polydimethylsiloxane (PDMS), and detaching them from the HOPG base. This results in flexible stamps containing embedded HOPG micro-pillar arrays with freshly cleaved stamping surfaces. The flexible HOPG/PDMS stamps are then brought into contact with substrate surfaces to site-specifically stamp graphene or few-layer graphene (FLG) arrays over large areas. The freshly cleaved nature of the micro-pillar surfaces in the flexible stamps, the low elastic modulus of the flexible stamps and the elimination of sidewall deposits on the micro-pillars allow for more uniform stamping, relative to the use of stiff HOPG stamps from earlier studies. This approach has the potential to expand the substrate choice for graphene or FLG stamping to include curved and/or flexible substrates that could have an impact on the burgeoning field of flexible/stretchable electronics. PMID:22595887

  13. Site-specific stamping of graphene micro-patterns over large areas using flexible stamps

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Hu; Reddy, Kongara M.; Padture, Nitin P.

    2012-06-01

    Site-specific stamping has the potential of becoming a low-cost, high-throughput method for depositing specific-shaped graphene micro-patterns over large areas on a wide variety of substrates. The use of an approach involving flexible stamps presented here represents an important advance towards reaching that potential. This approach entails lithographic creation (dry etching) of high-quality micro-pillar arrays of highly oriented pyrolytic graphite (HOPG) over large areas. This is followed by embedding the micro-pillar arrays in polydimethylsiloxane (PDMS), and detaching them from the HOPG base. This results in flexible stamps containing embedded HOPG micro-pillar arrays with freshly cleaved stamping surfaces. The flexible HOPG/PDMS stamps are then brought into contact with substrate surfaces to site-specifically stamp graphene or few-layer graphene (FLG) arrays over large areas. The freshly cleaved nature of the micro-pillar surfaces in the flexible stamps, the low elastic modulus of the flexible stamps and the elimination of sidewall deposits on the micro-pillars allow for more uniform stamping, relative to the use of stiff HOPG stamps from earlier studies. This approach has the potential to expand the substrate choice for graphene or FLG stamping to include curved and/or flexible substrates that could have an impact on the burgeoning field of flexible/stretchable electronics.

  14. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    PubMed Central

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  15. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices.

    PubMed

    Polat, Emre O; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm(2) flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  16. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-11-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them.

  17. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  18. Large-area, uniform white light LED source on a flexible substrate.

    PubMed

    Sher, Chin-Wei; Chen, Kuo-Ju; Lin, Chien-Chung; Han, Hau-Vei; Lin, Huang-Yu; Tu, Zong-Yi; Tu, Hsien-Hao; Honjo, Keiji; Jiang, Hsin-Yi; Ou, Sin-Liang; Horng, Ray-Hua; Li, Xiuling; Fu, Chien-Chung; Kuo, Hao-Chung

    2015-09-21

    This study demonstrates the flexible white LED structure with high lumen efficiency and uniform optical performance for neutral white and warm white CCT. Flip-chip LEDs were attached on a polyimide substrate with copper strips as electrical and thermal conduction paths. Yellow phosphors are mixed with polydimenthysiloxane (PDMS) to provide mechanical support and flexibility. The light efficiency of this device can reach 120 lm/W and 85% of light output uniformity of the emission area can be achieved. Moreover, the optical simulation is employed to evaluate various designs of this flexible film in order to obtain uniform output. Both the pitch between the individual devices and the thickness of the phosphor film are calculated for optimization purpose. This flexible white LED with high lumen efficiency and good reliability is suitable for the large area fixture in the general lighting applications. PMID:26406747

  19. Method of making large area conformable shape structures for detector/sensor applications using glass drawing technique and postprocessing

    DOEpatents

    Ivanov, Ilia N.; Simpson, John T.

    2012-01-24

    A method of making a large area conformable shape structure comprises drawing a plurality of tubes to form a plurality of drawn tubes, and cutting the plurality of drawn tubes into cut drawn tubes of a predetermined shape. The cut drawn tubes have a first end and a second end along the longitudinal direction of the cut drawn tubes. The method further comprises conforming the first end of the cut drawn tubes into a predetermined curve to form the large area conformable shape structure, wherein the cut drawn tubes contain a material.

  20. Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates

    PubMed Central

    Jin, Lichuan; Zhang, Dainan; Zhang, Huaiwu; Fang, Jue; Liao, Yulong; Zhou, Tingchuan; Liu, Cheng; Zhong, Zhiyong; Harris, Vincent G.

    2016-01-01

    Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10–180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400–1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths. PMID:27667259

  1. Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates

    NASA Astrophysics Data System (ADS)

    Jin, Lichuan; Zhang, Dainan; Zhang, Huaiwu; Fang, Jue; Liao, Yulong; Zhou, Tingchuan; Liu, Cheng; Zhong, Zhiyong; Harris, Vincent G.

    2016-09-01

    Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10–180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400–1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths.

  2. Design and fabrication of a flexible large area fabric transducer for bone healing application

    NASA Astrophysics Data System (ADS)

    Jadidian, Bahram

    The electromechanical transducers have found applications in their either passive or active modes. These applications include hydrophone, medical imaging, nondestructive evaluation, motors, sensors, actuators, civil and aerospace engineering. Other medical applications for ultrasonic transducers include therapeutics, osteosynthesis, lithotripsy, thrombolysis, and transdermal drug administration. During the past few decades, lead zirconate titanate (PZT), has been utilized in transducer applications in the form of a bulk piezoelectric ceramic and/or ceramic-polymer composites because of its high piezoelectric charge coefficient d33. The usage of piezoelectric ceramic/polymer composites allows designers to overcome some of the problems dealing with either monolithic piezoceramics or piezopolymers in transducer applications. In this work, a variety of composites with different connectivity patterns were formed. Composites with 1-3 connectivity were fabricated using bundling and collimating methods. Sized and unsized fibers were woven to form fabric. The fabric was used to form 3-3 composites and spiral structures. Square sheets of the fabric were laminated on top of each other, heat treated, and embedded in different types of polymer. The effect of applied pressure on the stack during heat treatment was studied. Plane fabric was formed in the spiral manner and used to construct piezocomposites. A piezoelectric transducer with high thickness coupling coefficient and its matching layer were exploited for bone healing application. One of the structures with the highest electromechanical properties, developed in this work, was chosen for the array fabrication. The spiral composite elements, with the best properties, were arranged in a 3 x 4 format embedded in a flexible polymer. The mechanical endurance of the elements and the array was studied. A large area flexible matching layer with low attenuation was developed. An extensive study was performed to determine the

  3. Laser Direct Write micro-fabrication of large area electronics on flexible substrates

    NASA Astrophysics Data System (ADS)

    Zacharatos, F.; Makrygianni, M.; Geremia, R.; Biver, E.; Karnakis, D.; Leyder, S.; Puerto, D.; Delaporte, P.; Zergioti, I.

    2016-06-01

    To date, Laser Direct Write (LDW) techniques, such as Laser Induced Forward Transfer (LIFT), selective laser ablation and selective laser sintering of metal nanoparticle (NP) ink layers are receiving growing attention for the printing of uniform and well-defined conductive patterns with resolution down to 10 μm. For flexible substrates in particular, selective laser sintering of such NP patterns has been widely applied, as a low temperature and high resolution process compatible with large area electronics. In this work, LDW of silver NP inks has been carried out on polyethylene-terephthalate (PET), polyethylene-naphthalate (PEN) and polyimide (PI) substrates to achieve low electrical resistivity electrodes. In more detail, high speed short pulsed (picosecond and nanosecond) lasers with repetition rates up to 1 MHz were used to print (LIFT) metal NP inks. We thus achieved uniform and continuous patterns with a minimum feature size of 1 μm and a total footprint larger than 1 cm2. Next, the printed patterns were laser sintered with ns pulses at 532 nm over a wide laser fluence window, resulting in an electrical resistivity of 10 μΩ cm. We carried out spatial beam shaping experiments to achieve a top-hat laser intensity profile and employed selective laser ablation of thin films (thickness on the order of 100 nm) to produce silver micro-electrodes with a resolution on the order of 10 μm and a low line edge roughness. Laser sintering was combined with laser ablation to constitute a fully autonomous micro-patterning technique of metallic micro-features, with a 10 μm resolution and geometrical characteristics tuned for interdigitated electrodes for sensor applications.

  4. A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications

    NASA Astrophysics Data System (ADS)

    Someya, Takao; Sekitani, Tsuyoshi; Iba, Shingo; Kato, Yusaku; Kawaguchi, Hiroshi; Sakurai, Takayasu

    2004-07-01

    It is now widely accepted that skin sensitivity will be very important for future robots used by humans in daily life for housekeeping and entertainment purposes. Despite this fact, relatively little progress has been made in the field of pressure recognition compared to the areas of sight and voice recognition, mainly because good artificial "electronic skin" with a large area and mechanical flexibility is not yet available. The fabrication of a sensitive skin consisting of thousands of pressure sensors would require a flexible switching matrix that cannot be realized with present silicon-based electronics. Organic field-effect transistors can substitute for such conventional electronics because organic circuits are inherently flexible and potentially ultralow in cost even for a large area. Thus, integration of organic transistors and rubber pressure sensors, both of which can be produced by low-cost processing technology such as large-area printing technology, will provide an ideal solution to realize a practical artificial skin, whose feasibility has been demonstrated in this paper. Pressure images have been taken by flexible active matrix drivers with organic transistors whose mobility reaches as high as 1.4 cm2/V·s. The device is electrically functional even when it is wrapped around a cylindrical bar with a 2-mm radius.

  5. A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications

    PubMed Central

    Someya, Takao; Sekitani, Tsuyoshi; Iba, Shingo; Kato, Yusaku; Kawaguchi, Hiroshi; Sakurai, Takayasu

    2004-01-01

    It is now widely accepted that skin sensitivity will be very important for future robots used by humans in daily life for housekeeping and entertainment purposes. Despite this fact, relatively little progress has been made in the field of pressure recognition compared to the areas of sight and voice recognition, mainly because good artificial “electronic skin” with a large area and mechanical flexibility is not yet available. The fabrication of a sensitive skin consisting of thousands of pressure sensors would require a flexible switching matrix that cannot be realized with present silicon-based electronics. Organic field-effect transistors can substitute for such conventional electronics because organic circuits are inherently flexible and potentially ultralow in cost even for a large area. Thus, integration of organic transistors and rubber pressure sensors, both of which can be produced by low-cost processing technology such as large-area printing technology, will provide an ideal solution to realize a practical artificial skin, whose feasibility has been demonstrated in this paper. Pressure images have been taken by flexible active matrix drivers with organic transistors whose mobility reaches as high as 1.4 cm2/V·s. The device is electrically functional even when it is wrapped around a cylindrical bar with a 2-mm radius. PMID:15226508

  6. Flexible ligand docking using conformational ensembles.

    PubMed Central

    Lorber, D. M.; Shoichet, B. K.

    1998-01-01

    Molecular docking algorithms suggest possible structures for molecular complexes. They are used to model biological function and to discover potential ligands. A present challenge for docking algorithms is the treatment of molecular flexibility. Here, the rigid body program, DOCK, is modified to allow it to rapidly fit multiple conformations of ligands. Conformations of a given molecule are pre-calculated in the same frame of reference, so that each conformer shares a common rigid fragment with all other conformations. The ligand conformers are then docked together, as an ensemble, into a receptor binding site. This takes advantage of the redundancy present in differing conformers of the same molecule. The algorithm was tested using three organic ligand protein systems and two protein-protein systems. Both the bound and unbound conformations of the receptors were used. The ligand ensemble method found conformations that resembled those determined in X-ray crystal structures (RMS values typically less than 1.5 A). To test the method's usefulness for inhibitor discovery, multi-compound and multi-conformer databases were screened for compounds known to bind to dihydrofolate reductase and compounds known to bind to thymidylate synthase. In both cases, known inhibitors and substrates were identified in conformations resembling those observed experimentally. The ligand ensemble method was 100-fold faster than docking a single conformation at a time and was able to screen a database of over 34 million conformations from 117,000 molecules in one to four CPU days on a workstation. PMID:9568900

  7. Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices

    NASA Astrophysics Data System (ADS)

    Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

    2016-06-01

    Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W‑1, external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

  8. Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices.

    PubMed

    Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

    2016-06-01

    Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W(-1), external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

  9. Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices

    NASA Astrophysics Data System (ADS)

    Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

    2016-06-01

    Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W-1, external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

  10. Flexible and printable paper-based strain sensors for wearable and large-area green electronics.

    PubMed

    Liao, Xinqin; Zhang, Zheng; Liao, Qingliang; Liang, Qijie; Ou, Yang; Xu, Minxuan; Li, Minghua; Zhang, Guangjie; Zhang, Yue

    2016-07-14

    Paper-based (PB) green electronics is an emerging and potentially game-changing technology due to ease of recycling/disposal, the economics of manufacture and the applicability to flexible electronics. Herein, new-type printable PB strain sensors (PPBSSs) from graphite glue (graphite powder and methylcellulose) have been fabricated. The graphite glue is exposed to thermal annealing to produce surface micro/nano cracks, which are very sensitive to compressive or tensile strain. The devices exhibit a gauge factor of 804.9, response time of 19.6 ms and strain resolution of 0.038%, all performance indicators attaining and even surpassing most of the recently reported strain sensors. Due to the distinctive sensing properties, flexibility and robustness, the PPBSSs are suitable for monitoring of diverse conditions such as structural strain, vibrational motion, human muscular movements and visual control.

  11. Semiconductor-based, large-area, flexible, electronic devices on {110}<100> oriented substrates

    DOEpatents

    Goyal, Amit

    2014-08-05

    Novel articles and methods to fabricate the same resulting in flexible, oriented, semiconductor-based, electronic devices on {110}<100> textured substrates are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  12. Flexible and printable paper-based strain sensors for wearable and large-area green electronics

    NASA Astrophysics Data System (ADS)

    Liao, Xinqin; Zhang, Zheng; Liao, Qingliang; Liang, Qijie; Ou, Yang; Xu, Minxuan; Li, Minghua; Zhang, Guangjie; Zhang, Yue

    2016-06-01

    Paper-based (PB) green electronics is an emerging and potentially game-changing technology due to ease of recycling/disposal, the economics of manufacture and the applicability to flexible electronics. Herein, new-type printable PB strain sensors (PPBSSs) from graphite glue (graphite powder and methylcellulose) have been fabricated. The graphite glue is exposed to thermal annealing to produce surface micro/nano cracks, which are very sensitive to compressive or tensile strain. The devices exhibit a gauge factor of 804.9, response time of 19.6 ms and strain resolution of 0.038%, all performance indicators attaining and even surpassing most of the recently reported strain sensors. Due to the distinctive sensing properties, flexibility and robustness, the PPBSSs are suitable for monitoring of diverse conditions such as structural strain, vibrational motion, human muscular movements and visual control.Paper-based (PB) green electronics is an emerging and potentially game-changing technology due to ease of recycling/disposal, the economics of manufacture and the applicability to flexible electronics. Herein, new-type printable PB strain sensors (PPBSSs) from graphite glue (graphite powder and methylcellulose) have been fabricated. The graphite glue is exposed to thermal annealing to produce surface micro/nano cracks, which are very sensitive to compressive or tensile strain. The devices exhibit a gauge factor of 804.9, response time of 19.6 ms and strain resolution of 0.038%, all performance indicators attaining and even surpassing most of the recently reported strain sensors. Due to the distinctive sensing properties, flexibility and robustness, the PPBSSs are suitable for monitoring of diverse conditions such as structural strain, vibrational motion, human muscular movements and visual control. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02172g

  13. The surface treatment of Ti meshes for use in large-area flexible dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xiao, Yaoming; Wu, Jihuai; Yue, Gentian; Lin, Jianming; Huang, Miaoliang; Fan, Leqing; Lan, Zhang

    2012-06-01

    We report that NaOH hydrothermal treatment and HF post-treatment of the titanium mesh for the Pt/Ti counter electrode improved the efficiency of dye-sensitized solar cells. High performance platinum nanoparticles have been sprayed onto Ti meshes to form counter electrodes for use in large-area flexible DSSCs using a vacuum thermal decomposition method at low temperature (120 °C). The obtained Pt/Ti counter electrode shows low charge-transfer resistance (57.52 Ω cm2 with active area of 80 cm2) and high electrocatalytic activity for the I3-/I- redox reaction. The photovoltaic properties and resistances of Pt/Ti counter electrodes with different HF post-treatment times of the NaOH treated Ti meshes have been investigated. The efficiency of the large-area (80 cm2) flexible DSSC reaches 6.17% under irradiation with a natural light intensity of 55 mW cm-2 measured outdoors.

  14. Conformational Flexibility in the Transmembrane Protein TSPO.

    PubMed

    Jaremko, Łukasz; Jaremko, Mariusz; Giller, Karin; Becker, Stefan; Zweckstetter, Markus

    2015-11-01

    The translocator protein (TSPO) is an integral membrane protein that interacts with a wide variety of endogenous ligands, such as cholesterol and porphyrins, and is also the target for several small molecules with substantial in vivo efficacy. When complexed with the TSPO-specific radioligand (R)-PK11195, TSPO folds into a rigid five-helix bundle. However, little is known about the structure and dynamics of TSPO in the absence of high-affinity ligands. By means of NMR spectroscopy, we show that TSPO exchanges between multiple conformations in the absence of (R)-PK11195. Extensive motions on time scales from pico- to microseconds occur all along the primary sequence of the protein, leading to a loss of stable tertiary interactions and local unfolding of the helical structure in the vicinity of the ligand-binding site. The flexible nature of TSPO highlights the importance of conformational plasticity in integral membrane proteins.

  15. Relationship between conformational flexibility and chelate cooperativity.

    PubMed

    Misuraca, M Cristina; Grecu, Tudor; Freixa, Zoraida; Garavini, Valentina; Hunter, Christopher A; van Leeuwen, Piet W N M; Segarra-Maset, M Dolores; Turega, Simon M

    2011-04-15

    A family of four biscarbamates (AA) and four bisphenols (DD) were synthesized, and H-bonding interactions between all AA•DD combinations were characterized using (1)H NMR titrations in carbon tetrachloride. A chemical double mutant cycle analysis shows that there are no secondary electrostatic interactions or allosteric cooperativity in these systems, and the system therefore provides an ideal platform for investigating the relationship between chemical structure and chelate cooperativity. Effective molarities (EMs) were measured for 12 different systems, where the number of rotors in the chains connecting the two H-bond sites was varied from 5 to 20. The association constants vary by less than an order of magnitude for all 12 complexes, and the variation in EM is remarkably small (0.1-0.9 M). The results provide a relationship between EM and the number of rotors in the connecting chains (r): EM ≈ 10r(-3/2). The value of 10 M is the upper limit for the value of EM for a noncovalent intramolecular interaction. Introduction of rotors reduces the value of EM from this maximum in accord with a random walk analysis of the encounter probability of the chain ends (r(-3/2)). Noncovalent EMs never reach the very high values observed for covalent processes, which places limitations on the magnitudes of the effects that one is likely to achieve through the use of chelate cooperativity in supramolecular assembly and catalysis. On the other hand, the decrease in EM due to the introduction of conformational flexibility is less dramatic than one might expect based on the behavior of covalent systems, which limits the losses in binding affinity caused by poor preorganization of the interaction sites.

  16. Femtosecond laser rapid fabrication of large-area rose-like micropatterns on freestanding flexible graphene films

    PubMed Central

    Shi, Xuesong; Li, Xin; Jiang, Lan; Qu, Liangti; Zhao, Yang; Ran, Peng; Wang, Qingsong; Cao, Qiang; Ma, Tianbao; Lu, Yongfeng

    2015-01-01

    We developed a simple, scalable and high-throughput method for fabrication of large-area three-dimensional rose-like microflowers with controlled size, shape and density on graphene films by femtosecond laser micromachining. The novel biomimetic microflower that composed of numerous turnup graphene nanoflakes can be fabricated by only a single femtosecond laser pulse, which is efficient enough for large-area patterning. The graphene films were composed of layer-by-layer graphene nanosheets separated by nanogaps (~10–50 nm), and graphene monolayers with an interlayer spacing of ~0.37 nm constituted each of the graphene nanosheets. This unique hierarchical layering structure of graphene films provides great possibilities for generation of tensile stress during femtosecond laser ablation to roll up the nanoflakes, which contributes to the formation of microflowers. By a simple scanning technique, patterned surfaces with controllable densities of flower patterns were obtained, which can exhibit adhesive superhydrophobicity. More importantly, this technique enables fabrication of the large-area patterned surfaces at centimeter scales in a simple and efficient way. This study not only presents new insights of ultrafast laser processing of novel graphene-based materials but also shows great promise of designing new materials combined with ultrafast laser surface patterning for future applications in functional coatings, sensors, actuators and microfluidics. PMID:26615800

  17. Femtosecond laser rapid fabrication of large-area rose-like micropatterns on freestanding flexible graphene films

    NASA Astrophysics Data System (ADS)

    Shi, Xuesong; Li, Xin; Jiang, Lan; Qu, Liangti; Zhao, Yang; Ran, Peng; Wang, Qingsong; Cao, Qiang; Ma, Tianbao; Lu, Yongfeng

    2015-11-01

    We developed a simple, scalable and high-throughput method for fabrication of large-area three-dimensional rose-like microflowers with controlled size, shape and density on graphene films by femtosecond laser micromachining. The novel biomimetic microflower that composed of numerous turnup graphene nanoflakes can be fabricated by only a single femtosecond laser pulse, which is efficient enough for large-area patterning. The graphene films were composed of layer-by-layer graphene nanosheets separated by nanogaps (~10-50 nm), and graphene monolayers with an interlayer spacing of ~0.37 nm constituted each of the graphene nanosheets. This unique hierarchical layering structure of graphene films provides great possibilities for generation of tensile stress during femtosecond laser ablation to roll up the nanoflakes, which contributes to the formation of microflowers. By a simple scanning technique, patterned surfaces with controllable densities of flower patterns were obtained, which can exhibit adhesive superhydrophobicity. More importantly, this technique enables fabrication of the large-area patterned surfaces at centimeter scales in a simple and efficient way. This study not only presents new insights of ultrafast laser processing of novel graphene-based materials but also shows great promise of designing new materials combined with ultrafast laser surface patterning for future applications in functional coatings, sensors, actuators and microfluidics.

  18. Next Generation Non-Vacuum, Maskless, Low Temperature Nanoparticle Ink Laser Digital Direct Metal Patterning for a Large Area Flexible Electronics

    PubMed Central

    Yeo, Junyeob; Hong, Sukjoon; Lee, Daehoo; Hotz, Nico; Lee, Ming-Tsang; Grigoropoulos, Costas P.; Ko, Seung Hwan

    2012-01-01

    Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition– and photolithography-based conventional metal patterning processes. The “digital” nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm) and high-performance flexible organic field effect transistor arrays. PMID:22900011

  19. Next generation non-vacuum, maskless, low temperature nanoparticle ink laser digital direct metal patterning for a large area flexible electronics.

    PubMed

    Yeo, Junyeob; Hong, Sukjoon; Lee, Daehoo; Hotz, Nico; Lee, Ming-Tsang; Grigoropoulos, Costas P; Ko, Seung Hwan

    2012-01-01

    Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition- and photolithography-based conventional metal patterning processes. The "digital" nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm) and high-performance flexible organic field effect transistor arrays.

  20. Large area in situ fabrication of poly(pyrrole)-nanowires on flexible thermoplastic films using nanocontact printing

    NASA Astrophysics Data System (ADS)

    Garcia-Cruz, Alvaro; Lee, Michael; Marote, Pedro; Zine, Nadia; Sigaud, Monique; Bonhomme, Anne; Pruna, Raquel; Lopez, Manuel; Bausells, Joan; Jaffrezic, Nicole; Errachid, Abdelhamid

    2016-08-01

    Highly efficient nano-engineering tools will certainly revolutionize the biomedical and sensing devices research and development in the years to come. Here, we present a novel high performance conducting poly(pyrrole) nanowires (PPy-NW) patterning technology on thermoplastic surfaces (poly(ethylene terephthalate (PETE), poly(ethylene 2,6-naphthalate (PEN), polyimide (PI), and cyclic olefin copolymer) using nanocontact printing and controlled chemical polymerization (nCP-CCP) technique. The technique uses a commercial compact disk as a template to produce nanopatterned polydimethylsiloxane (PDMS) stamps. The PDMS nanopatterned stamp was applied to print the PPy-NWs and the developed technology of nCP-CCP produced 3D conducting nanostructures. This new and very promising nanopatterning technology was achieved in a single step and with a low cost of fabrication over large areas.

  1. Integrating anti-reflection and superhydrophobicity of moth-eye-like surface morphology on a large-area flexible substrate

    NASA Astrophysics Data System (ADS)

    Liu, Chia-Hsing; Niu, Pei-Lun; Sung, Cheng-Kuo

    2014-01-01

    This paper proposes an ultraviolet nanoimprint lithography (UV-NIL) roll-to-roll (R2R) process with argon and oxygen (Ar-O2) plasma ashing and coating of a dilute perfluorodecyltrichlorosilane (FDTS) layer to fabricate the large-area moth-eye-like surface morphology on a polyethylene terephthalate substrate. By using Maxwell-Garnett's effective medium theory, the optimal dimensions of the moth-eye-like surface morphology was designed and fabricated with UV-NIL R2R process to obtain maximum transmittance ratio. In addition, the base angle (θ = 30.1°) of the moth-eye-like surface morphology was modified with Ar-O2 plasma ashing and coated with a dilute FDTS layer to possess both superhydrophobic and air-retention properties. This increases both the transmittance ratio of 4% and contact angle to 153°.

  2. {100}<100> or 45.degree.-rotated {100}<100>, semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2012-05-15

    Novel articles and methods to fabricate the same resulting in flexible, {100}<100> or 45.degree.-rotated {100}<100> oriented, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  3. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates

    NASA Astrophysics Data System (ADS)

    Nagel, Robin D.; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-03-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material.

  4. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates.

    PubMed

    Nagel, Robin D; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-12-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material. PMID:26976429

  5. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates.

    PubMed

    Nagel, Robin D; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-12-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material.

  6. Vertically building Zn2SnO4 nanowire arrays on stainless steel mesh toward fabrication of large-area, flexible dye-sensitized solar cells.

    PubMed

    Li, Zhengdao; Zhou, Yong; Bao, Chunxiong; Xue, Guogang; Zhang, Jiyuan; Liu, Jianguo; Yu, Tao; Zou, Zhigang

    2012-06-01

    Zn(2)SnO(4) nanowire arrays were for the first time grown onto a stainless steel mesh (SSM) in a binary ethylenediamine (En)/water solvent system using a solvothermal route. The morphology evolution following this reaction was carefully followed to understand the formation mechanism. The SSM-supported Zn(2)SnO(4) nanowire was utilized as a photoanode for fabrication of large-area (10 cm × 5 cm size as a typical sample), flexible dye-sensitized solar cells (DSSCs). The synthesized Zn(2)SnO(4) nanowires exhibit great bendability and flexibility, proving potential advantage over other metal oxide nanowires such as TiO(2), ZnO, and SnO(2) for application in flexible solar cells. Relative to the analogous Zn(2)SnO(4) nanoparticle-based flexible DSSCs, the nanowire geometry proves to enhance solar energy conversion efficiency through enhancement of electron transport. The bendable nature of the DSSCs without obvious degradation of efficiency and facile scale up gives the as-made flexible solar cell device potential for practical application.

  7. Rolling-based direct-transfer printing: A process for large-area transfer of micro- and nanostructures onto flexible substrates

    NASA Astrophysics Data System (ADS)

    Grierson, D. S.; Flack, F. S.; Lagally, M. G.; Turner, K. T.

    2016-09-01

    A rolling-based printing approach for transferring arrays of patterned micro- and nano-structures directly from rigid fabrication substrates onto flexible substrates is presented. Transfer-printing experiments show that the new process can achieve high-yield and high-fidelity transfer of silicon nanomembrane components with diverse architectures to polyethylene terephthalate substrates over chip-scale areas (>1 × 1 cm2) in <0.3 s. The underlying mechanics of the process are investigated through finite element simulations of the contact and transfer process. These mechanics models provide guidance for controlling the contact area and strain in the flexible substrate during transfer, both of which are key for achieving reproducible and controlled component transfer over large areas.

  8. A KINETIC ANALYSIS OF THE CONFORMATIONAL FLEXIBILITY OF STEROID HORMONES

    EPA Science Inventory

    For a set of 10 androgen steroids and estradiol (E2), the kinetic feasibility of conformation flexibility of the cyclic moieties was studied under the constraint of maintaining the B/C trans and C/D trans ring fusion of the natural and biologically active enantiomer. To this end,...

  9. Conformal surface plasmons propagating on ultrathin and flexible films

    PubMed Central

    Shen, Xiaopeng; Cui, Tie Jun; Martin-Cano, Diego; Garcia-Vidal, Francisco J.

    2013-01-01

    Surface plasmon polaritons (SPPs) are localized surface electromagnetic waves that propagate along the interface between a metal and a dielectric. Owing to their inherent subwavelength confinement, SPPs have a strong potential to become building blocks of a type of photonic circuitry built up on 2D metal surfaces; however, SPPs are difficult to control on curved surfaces conformably and flexibly to produce advanced functional devices. Here we propose the concept of conformal surface plasmons (CSPs), surface plasmon waves that can propagate on ultrathin and flexible films to long distances in a wide broadband range from microwave to mid-infrared frequencies. We present the experimental realization of these CSPs in the microwave regime on paper-like dielectric films with a thickness 600-fold smaller than the operating wavelength. The flexible paper-like films can be bent, folded, and even twisted to mold the flow of CSPs. PMID:23248311

  10. Distal histidine conformational flexibility in dehaloperoxidase from Amphitrite ornata

    SciTech Connect

    Chen, Zuxu; de Serrano, Vesna; Betts, Laurie; Franzen, Stefan

    2009-01-28

    The enzyme dehaloperoxidase (DHP) from the terebellid polychaete Amphitrite ornata is a heme protein which has a globin fold but can function as both a hemoglobin and a peroxidase. As a peroxidase, DHP is capable of converting 2,4,6-trihalophenols to the corresponding 2,6-dihaloquinones in the presence of hydrogen peroxide. As a hemoglobin, DHP cycles between the oxy and deoxy states as it reversibly binds oxygen for storage. Here, it is reported that the distal histidine, His55, exhibits conformational flexibility in the deoxy form and is consequently observed in two solvent-exposed conformations more than 9.5 {angstrom} away from the heme. These conformations are analogous to the open conformation of sperm whale myoglobin. The heme iron in deoxy ferrous DHP is five-coordinate and has an out-of-plane displacement of 0.25 {angstrom} from the heme plane. The observation of five-coordinate heme iron with His55 in a remote solvent-exposed conformation is consistent with the hypothesis that His55 interacts with heme iron ligands through hydrogen bonding in the closed conformation. Since His55 is also displaced by the binding of 4-iodophenol in an internal pocket, these results provide new insight into the correlation between heme iron ligation, molecular binding in the distal pocket and the conformation of the distal histidine in DHP.

  11. Global mapping of DNA conformational flexibility on Saccharomyces cerevisiae.

    PubMed

    Menconi, Giulia; Bedini, Andrea; Barale, Roberto; Sbrana, Isabella

    2015-04-01

    In this study we provide the first comprehensive map of DNA conformational flexibility in Saccharomyces cerevisiae complete genome. Flexibility plays a key role in DNA supercoiling and DNA/protein binding, regulating DNA transcription, replication or repair. Specific interest in flexibility analysis concerns its relationship with human genome instability. Enrichment in flexible sequences has been detected in unstable regions of human genome defined fragile sites, where genes map and carry frequent deletions and rearrangements in cancer. Flexible sequences have been suggested to be the determinants of fragile gene proneness to breakage; however, their actual role and properties remain elusive. Our in silico analysis carried out genome-wide via the StabFlex algorithm, shows the conserved presence of highly flexible regions in budding yeast genome as well as in genomes of other Saccharomyces sensu stricto species. Flexibile peaks in S. cerevisiae identify 175 ORFs mapping on their 3'UTR, a region affecting mRNA translation, localization and stability. (TA)n repeats of different extension shape the central structure of peaks and co-localize with polyadenylation efficiency element (EE) signals. ORFs with flexible peaks share common features. Transcripts are characterized by decreased half-life: this is considered peculiar of genes involved in regulatory systems with high turnover; consistently, their function affects biological processes such as cell cycle regulation or stress response. Our findings support the functional importance of flexibility peaks, suggesting that the flexible sequence may be derived by an expansion of canonical TAYRTA polyadenylation efficiency element. The flexible (TA)n repeat amplification could be the outcome of an evolutionary neofunctionalization leading to a differential 3'-end processing and expression regulation in genes with peculiar function. Our study provides a new support to the functional role of flexibility in genomes and a

  12. The design and realization of a large-area flexible nanofiber-based mat for pollutant degradation: an application in photocatalysis

    NASA Astrophysics Data System (ADS)

    Shang, Meng; Wang, Wenzhong; Sun, Songmei; Gao, Erping; Zhang, Zhijie; Zhang, Ling; O'Hayre, Ryan

    2013-05-01

    This work demonstrates a novel multifunctional nanofibrous mat for photocatalytic applications based on TiO2 nanocables functionalized by Ag nanoparticles and coated with a thin (~2 nm) graphitic shell. In this mat, which was realized by an electrospinning technique, each component serves a unique function: the carbon coating acts as both an adsorption material for capturing pollutants and as a charge-transfer material, the Ag nanoparticles act as a visible-light sensitizing agent and also as a charge-transfer material, finally the TiO2 nanocable mat acts as a UV sensitive photocatalytic matrix and as the flexible substrate for the other functional components. This multicomponent nanocable mat exhibits excellent photocatalytic activity under simulated solar irradiation for the degradation of model pollutants including RhB and phenol. The significant photocatalytic properties are attributed to the synergetic effect of the three functional components and the unique charge transport ``freeway'' property of the nanofibrous mat. In addition, the porous carbon coating infiltrated into the nanocable matrix endows the mat with excellent flexibility and enables robust, large-area (10 × 10 cm) fabrication, representing a significant advantage over previous brittle ceramic nanofibrous mat photocatalyst substrates. This study provides new insight into the design and preparation of an advanced, yet commercially practical and scaleable photocatalytic composite membrane material. The as-prepared photocatalytic mat might also be of interest in solar cell, catalysis, separation technology, biomedical engineering, and nanotechnology.

  13. Large-area, transparent, and flexible infrared photodetector fabricated using P-N junctions formed by N-doping chemical vapor deposition grown graphene.

    PubMed

    Liu, Nan; Tian, He; Schwartz, Gregor; Tok, Jeffrey B-H; Ren, Tian-Ling; Bao, Zhenan

    2014-07-01

    Graphene is a highly promising material for high speed, broadband, and multicolor photodetection. Because of its lack of bandgap, individually gated P- and N-regions are needed to fabricate photodetectors. Here we report a technique for making a large-area photodetector on the basis of controllable fabrication of graphene P-N junctions. Our selectively doped chemical vapor deposition (CVD) graphene photodetector showed a ∼5% modulation of conductance under global IR irradiation. By comparing devices of various geometries, we identify that both the homogeneous and the P-N junction regions contribute competitively to the photoresponse. Furthermore, we demonstrate that our two-terminal graphene photodetector can be fabricated on both transparent and flexible substrates without the need for complex fabrication processes used in electrically gated three-terminal devices. This represents the first demonstration of a fully transparent and flexible graphene-based IR photodetector that exhibits both good photoresponsivity and high bending capability. This simple approach should facilitate the development of next generation high-performance IR photodetectors.

  14. The design and realization of a large-area flexible nanofiber-based mat for pollutant degradation: an application in photocatalysis.

    PubMed

    Shang, Meng; Wang, Wenzhong; Sun, Songmei; Gao, Erping; Zhang, Zhijie; Zhang, Ling; O'Hayre, Ryan

    2013-06-01

    This work demonstrates a novel multifunctional nanofibrous mat for photocatalytic applications based on TiO2 nanocables functionalized by Ag nanoparticles and coated with a thin (~2 nm) graphitic shell. In this mat, which was realized by an electrospinning technique, each component serves a unique function: the carbon coating acts as both an adsorption material for capturing pollutants and as a charge-transfer material, the Ag nanoparticles act as a visible-light sensitizing agent and also as a charge-transfer material, finally the TiO2 nanocable mat acts as a UV sensitive photocatalytic matrix and as the flexible substrate for the other functional components. This multicomponent nanocable mat exhibits excellent photocatalytic activity under simulated solar irradiation for the degradation of model pollutants including RhB and phenol. The significant photocatalytic properties are attributed to the synergetic effect of the three functional components and the unique charge transport "freeway" property of the nanofibrous mat. In addition, the porous carbon coating infiltrated into the nanocable matrix endows the mat with excellent flexibility and enables robust, large-area (10 × 10 cm) fabrication, representing a significant advantage over previous brittle ceramic nanofibrous mat photocatalyst substrates. This study provides new insight into the design and preparation of an advanced, yet commercially practical and scaleable photocatalytic composite membrane material. The as-prepared photocatalytic mat might also be of interest in solar cell, catalysis, separation technology, biomedical engineering, and nanotechnology.

  15. Deterministic growth of AgTCNQ and CuTCNQ nanowires on large-area reduced graphene oxide films for flexible optoelectronics

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Lu, Zhufeng; Gu, Li; Cai, Liling; Cao, Xuebo

    2013-11-01

    We describe a synchronous reduction and assembly procedure to directly produce large-area reduced graphene oxide (rGO) films sandwiched by a high density of metal nanoparticles (silver and copper). Further, by using the sandwiched metal NPs as sources, networks consisting of AgTCNQ and CuTCNQ nanowires were deterministically grown from the rGO films, forming structurally and functionally integrated rGO/metal-TCNQ hybrid films with outstanding flexibility, bending endurance, and electrical stability. Interestingly, due to the p-type nature of the rGO film and the n-type nature of the metal-TCNQ NWs, the hybrid films are essentially thin-film p-n junctions which are useful in ubiquitous electronics and optoelectronics. Measurements of the optoelectronic properties demonstrate that the rGO/metal-TCNQ hybrid films exhibit substantial photoconductivity and highly reproducible photoswitching behaviours. The present approach may open the door to the versatile and deterministic integration of functional nanostructures into flexible conducting substrates and provide an important step towards producing low-cost and high-performance soft electronic and optoelectronic devices.

  16. Conformation and hydrogen ion titration of proteins: a continuum electrostatic model with conformational flexibility.

    PubMed Central

    You, T J; Bashford, D

    1995-01-01

    A new method for including local conformational flexibility in calculations of the hydrogen ion titration of proteins using macroscopic electrostatic models is presented. Intrinsic pKa values and electrostatic interactions between titrating sites are calculated from an ensemble of conformers in which the positions of titrating side chains are systematically varied. The method is applied to the Asp, Glu, and Tyr residues of hen lysozyme. The effects of different minimization and/or sampling protocols for both single-conformer and multi-conformer calculations are studied. For single-conformer calculations it is found that the results are sensitive to the choice of all-hydrogen versus polar-hydrogen-only atomic models and to the minimization protocol chosen. The best overall agreement of single-conformer calculations with experiment is obtained with an all-hydrogen model and either a two-step minimization process or minimization using a high dielectric constant. Multi-conformational calculations give significantly improved agreement with experiment, slightly smaller shifts between model compound pKa values and calculated intrinsic pKa values, and reduced sensitivity of the intrinsic pKa calculations to the initial details of the structure compared to single-conformer calculations. The extent of these improvements depends on the type of minimization used during the generation of conformers, with more extensive minimization giving greater improvements. The ordering of the titrations of the active-site residues, Glu-35 and Asp-52, is particularly sensitive to the minimization and sampling protocols used. The balance of strong site-site interactions in the active site suggests a need for including site-site conformational correlations. Images FIGURE 1 PMID:8580316

  17. The valence electronic structure and conformational flexibility of epichlorohydrin.

    PubMed

    Stranges, S; Alagia, M; Decleva, P; Stener, M; Fronzoni, G; Toffoli, D; Speranza, M; Catone, D; Turchini, S; Prosperi, T; Zema, N; Contini, G; Keheyan, Y

    2011-07-21

    The electronic structure of epichlorohydrin is investigated in the whole valence region by a combined experimental and theoretical study. The issue of controversial assignments of the molecular electronic structure is here addressed. Photoelectron spectra (PES) and Threshold Photoelectron spectra (TPES) of room temperature molecules in the gas phase are recorded. Geometries and energies of the stable conformers due to internal rotation of the C-C-C-Cl dihedral angle, gauche-II (g-II), gauche-I (g-I), and cis, are calculated, and the effect of the conformational flexibility on the photoionization energetics is studied by DFT and 2h-1p Configuration Interaction (CI) methods. Strong breakdown of the Koopmans Theorem (KT) is obtained for the four outermost ionizations, which are further investigated by higher level ab initio calculations. The full assignment of the spectrum is put on a firm basis by the combination of experimental and theoretical results. The orbital composition from correlated calculations is found closer to the DFT orbitals, which are then used to analyze the electronic structure of the molecule. The Highest Occupied Molecular Orbital (HOMO) and HOMO--2 are n(O)/n(Cl) mixed orbitals. The nature of each valence MO is generally preserved in all the conformers, although the magnitude of the n(O)/n(Cl) mixing in HOMO and HOMO--2 varies to some extent with the C-C-C-Cl dihedral angle. The low energy part of the HOMO PE band is predicted to be substantially affected by the conformational flexibility, as experimentally observed in the spectra. The rest of the spectrum is described in terms of the dominant conformer g-II, and a good agreement between experiment and theory is found. The inner-valence PE spectrum is characterized by satellite structures, due to electron correlation effects, which are interpreted by means of 2h-1p CI calculations.

  18. A chemical chaperone induces inhomogeneous conformational changes in flexible proteins.

    PubMed

    Hamdane, Djemel; Velours, Christophe; Cornu, David; Nicaise, Magali; Lombard, Murielle; Fontecave, Marc

    2016-07-27

    Organic osmolytes also known as chemical chaperones are major cellular compounds that favor, by an unclear mechanism, protein's compaction and stabilization of the native state. Here, we have examined the chaperone effect of the naturally occurring trimethylamine N-oxide (TMAO) osmolyte on a loosely packed protein (LPP), known to be a highly flexible form, using an apoprotein mutant of the flavin-dependent RNA methyltransferase as a model. Thermal and chemical denaturation experiments showed that TMAO stabilizes the structural integrity of the apoprotein dramatically. The denaturation reaction is irreversible indicating that the stability of the apoprotein is under kinetic control. This result implies that the stabilization is due to a TMAO-induced reconfiguration of the flexible LPP state, which leads to conformational limitations of the apoprotein likely driven by favorable entropic contribution. Evidence for the conformational perturbation of the apoprotein had been obtained through several biophysical approaches notably analytical ultracentrifugation, circular dichroism, fluorescence spectroscopy, labelling experiments and proteolysis coupled to mass spectrometry. Unexpectedly, TMAO promotes an overall elongation or asymmetrical changes of the hydrodynamic shape of the apoprotein without alteration of the secondary structure. The modulation of the hydrodynamic properties of the protein is associated with diverse inhomogenous conformational changes: loss of the solvent accessible cavities resulting in a dried protein matrix; some side-chain residues initially buried become solvent exposed while some others become hidden. Consequently, the TMAO-induced protein state exhibits impaired capability in the flavin binding process. Our study suggests that the nature of protein conformational changes induced by the chemical chaperones may be specific to protein packing and plasticity. This could be an efficient mechanism by which the cell controls and finely tunes the

  19. Investigation of the interfacial adhesion of the transparent conductive oxide films to large-area flexible polymer substrates using laser-induced thermo-mechanical stresses

    NASA Astrophysics Data System (ADS)

    Park, Jin-Woo; Lee, Seung-Ho; Yang, Chan-Woo

    2013-08-01

    In this study, we investigated the interfacial adhesion strength (σint) of transparent conductive oxide (TCO) coatings on polymer substrates using a nanosecond Nd:YAG pulsed laser. We compared our results with those achieved using conventional testing methods such as bending and fragmentation tests as well as theoretical calculations. In the fragmentation and bending tests, mechanical compressive stress is induced in the film due to mismatches in Poisson's ratio and Young's modulus between the substrate and film. But, the incident laser makes the film under compression due to the mismatch in thermal expansion between the TCO and the polymer substrate. With a pulse incident to the substrate, the TCO rapidly expands by laser-induced instant heating while the transparent polymer does little, which causes the TCO to buckle and delaminate over the critical pulse energy. The critical compressive stress that scales with σint was calculated using simple equations, which agreed well with the results from previous theoretical calculations. Because the films preferentially delaminate at the defects and grain boundaries, this technique also provided useful information regarding the interface microstructures. Moreover, because the laser can scan over large areas, this method is suitable for flexible substrates that are produced by a roll-to-roll process. Nevertheless, the mechanical stress introduced by the bending and fragmentation tests causes the TCO to buckle without interfacial delamination. Hence, the stresses at the buckling disagreed with the results obtained from the laser test and the theoretical calculations.

  20. Large-area flexible monolithic ITO/WO3/Nb2O5/NiVOχ/ITO electrochromic devices prepared by using magnetron sputter deposition

    NASA Astrophysics Data System (ADS)

    Tang, Chien-Jen; Ye, Jia-Ming; Yang, Yueh-Ting; He, Ju-Liang

    2016-05-01

    Electrochromic devices (ECDs) have been applied in smart windows to control the transmission of sunlight in green buildings, saving up to 40-50% electricity consumption and ultimately reducing carbon dioxide emissions. However, the high manufacturing costs and difficulty of transportation of conventional massive large area ECDs has limited widespread applications. A unique design replacing the glass substrate commonly used in the ECD windows with inexpensive, light-weight and flexible polymeric substrate materials would accelerate EC adoption allowing them to be supplemented for regular windows without altering window construction. In this study, an ITO/WO3/Nb2O5/NiVOχ/ITO all-solid-state monolithic ECD with an effective area of 24 cm × 18 cm is successfully integrated on a PET substrate by using magnetron sputter deposition. The electrochromic performance and bending durability of the resultant material are also investigated. The experimental results indicate that the ultimate response times for the prepared ECD is 6 s for coloring at an applied voltage of -3 V and 5 s for bleaching at an applied voltage of +3 V, respectively. The optical transmittances for the bleached and colored state at a wavelength of 633 nm are 53% and 11%, respectively. The prepared ECD can sustain over 8000 repeated coloring and bleaching cycles, as well as tolerate a bending radius of curvature of 7.5 cm.

  1. Flexible conformable hydrophobized surfaces for turbulent flow drag reduction.

    PubMed

    Brennan, Joseph C; Geraldi, Nicasio R; Morris, Robert H; Fairhurst, David J; McHale, Glen; Newton, Michael I

    2015-05-15

    In recent years extensive work has been focused onto using superhydrophobic surfaces for drag reduction applications. Superhydrophobic surfaces retain a gas layer, called a plastron, when submerged underwater in the Cassie-Baxter state with water in contact with the tops of surface roughness features. In this state the plastron allows slip to occur across the surface which results in a drag reduction. In this work we report flexible and relatively large area superhydrophobic surfaces produced using two different methods: Large roughness features were created by electrodeposition on copper meshes; Small roughness features were created by embedding carbon nanoparticles (soot) into Polydimethylsiloxane (PDMS). Both samples were made into cylinders with a diameter under 12 mm. To characterize the samples, scanning electron microscope (SEM) images and confocal microscope images were taken. The confocal microscope images were taken with each sample submerged in water to show the extent of the plastron. The hydrophobized electrodeposited copper mesh cylinders showed drag reductions of up to 32% when comparing the superhydrophobic state with a wetted out state. The soot covered cylinders achieved a 30% drag reduction when comparing the superhydrophobic state to a plain cylinder. These results were obtained for turbulent flows with Reynolds numbers 10,000 to 32,500.

  2. Flexible conformable hydrophobized surfaces for turbulent flow drag reduction

    PubMed Central

    Brennan, Joseph C; Geraldi, Nicasio R; Morris, Robert H; Fairhurst, David J; McHale, Glen; Newton, Michael I

    2015-01-01

    In recent years extensive work has been focused onto using superhydrophobic surfaces for drag reduction applications. Superhydrophobic surfaces retain a gas layer, called a plastron, when submerged underwater in the Cassie-Baxter state with water in contact with the tops of surface roughness features. In this state the plastron allows slip to occur across the surface which results in a drag reduction. In this work we report flexible and relatively large area superhydrophobic surfaces produced using two different methods: Large roughness features were created by electrodeposition on copper meshes; Small roughness features were created by embedding carbon nanoparticles (soot) into Polydimethylsiloxane (PDMS). Both samples were made into cylinders with a diameter under 12 mm. To characterize the samples, scanning electron microscope (SEM) images and confocal microscope images were taken. The confocal microscope images were taken with each sample submerged in water to show the extent of the plastron. The hydrophobized electrodeposited copper mesh cylinders showed drag reductions of up to 32% when comparing the superhydrophobic state with a wetted out state. The soot covered cylinders achieved a 30% drag reduction when comparing the superhydrophobic state to a plain cylinder. These results were obtained for turbulent flows with Reynolds numbers 10,000 to 32,500. PMID:25975704

  3. The incorporation of protein flexibility and conformational energy penalties in docking screens to improve ligand discovery

    PubMed Central

    Fischer, Marcus; Coleman, Ryan G.; Fraser, James S.; Shoichet, Brian K.

    2014-01-01

    Proteins fluctuate between alternative conformations, which presents a challenge for ligand discovery because such flexibility is difficult to treat computationally owing to problems with conformational sampling and energy weighting. Here, we describe a flexible-docking method that samples and weights protein conformations using experimentally-derived conformations as a guide. The crystallographically refined occupancies of these conformations, which are observable in an apo receptor structure, define energy penalties for docking. In a large prospective library screen, we identified new ligands that target specific receptor conformations of a cavity in Cytochrome c Peroxidase, and we confirm both ligand pose and associated receptor conformation predictions by crystallography. The inclusion of receptor flexibility led to ligands with new chemotypes and physical properties. By exploiting experimental measures of loop and side chain flexibility, this method can be extended to the discovery of new ligands for hundreds of targets in the Protein Data Bank where similar experimental information is available. PMID:24950326

  4. Conformational flexibility in small biomolecules: tryptamine and 3-indole-propionic acid

    NASA Astrophysics Data System (ADS)

    Carney, Joel R.; Zwier, Timothy S.

    2001-06-01

    A combined experimental and theoretical study is used to probe the conformational preferences of two flexible tryptophan analogs, tryptamine (TRA) and 3-indole-propionic acid (IPA). Resonant ion-dip infrared spectroscopy provides infrared spectra of single conformations of these molecules free from interference from one another. Density functional theory Becke3LYP calculations are used to predict relative energies for the conformers, while relaxed potential energy scans determine the barrier heights separating the minima. The different forms of the potential energy surfaces along the flexible coordinates for the two molecules provide a coherent explanation for the observed conformational preferences.

  5. A molecular dynamics description of the conformational flexibility of the L-iduronate ring in glycosaminoglycans.

    PubMed

    Angulo, Jesús; Nieto, Pedro M; Martín-Lomas, Manuel

    2003-07-01

    For a synthetic hexasaccharide model it is shown that the conformational flexibility of the L-iduronate ring in glycosaminoglycans can be adequately described by using the PME methodology together with simulation protocols suitable for highly charged systems. PMID:12868729

  6. A molecular dynamics description of the conformational flexibility of the L-iduronate ring in glycosaminoglycans.

    PubMed

    Angulo, Jesús; Nieto, Pedro M; Martín-Lomas, Manuel

    2003-07-01

    For a synthetic hexasaccharide model it is shown that the conformational flexibility of the L-iduronate ring in glycosaminoglycans can be adequately described by using the PME methodology together with simulation protocols suitable for highly charged systems.

  7. Wormlike micelle assisted rod coating: a general method for facile fabrication of large-area conductive nanomaterial thin layer onto flexible plastics.

    PubMed

    Xie, Jingyi; Wang, Huan; Bai, Huadong; Yang, Peng; Shi, Mengxue; Guo, Peng; Wang, Chen; Yang, Wantai; Song, Huaihe

    2012-06-27

    Through combined application of wormlike-micelle and rod-coating technique, a general method was demonstrated for the facile reparation of thin transparent conductive films (TCF) of various nanomaterials and their hybrids on flexible plastics. The cetyltrimethylammonium hydroxide (CTAOH)/p-toluenesulfonic acid (CTAT) wormlike micelle system was selected for both the dispersion of different nanomaterials and the enhancement of viscosities of the coating fluids. With the single-walled carbon nanotubes (SWNTs)/wormlike micelle aqueous dispersions as coating fluid, TCFs of SWNTs on flexible poly(ethylene terephthalate) (PET) substrates made by rod-coating method were demonstrated. After doping by immersion into thionyl chloride solution, the sheet resistance of SWNTs thin films, which had a transmittance of about 78%, was as low as 480Ω/sq. This coating method was extended to the preparation of thin films or networks of other materials such as reduced graphene oxide and Ag nanowires. The obtained TCF from Ag nanowire networks has a low sheet resistance of 17Ω/sq, which is comparable to the value of best indium tin oxide (ITO) coating on plastic substrates. Finally, hybrid thin films of different nanomaterials were demonstrated by this method. PMID:22551382

  8. Consequences of conformational flexibility in hydrogen-bond-driven self-assembly processes.

    PubMed

    Berrocal, José Augusto; Di Meo, Florent; García-Iglesias, Miguel; Gosens, Ronald P J; Meijer, E W; Linares, Mathieu; Palmans, Anja R A

    2016-09-18

    We report the synthesis and self-assembly of chiral, conformationally flexible C3-symmetrical trisamides. A strong Cotton effect is observed for the supramolecular polymers in linear alkanes but not in cyclic alkanes. MD simulations suggest 2 : 1 conformations of the amides within the aggregates in both types of solvents, but a chiral bias in only linear alkanes. PMID:27525556

  9. Cyclic Constraints on Conformational Flexibility in γ-PEPTIDES: Conformation-Specific IR and UV Spectroscopy

    NASA Astrophysics Data System (ADS)

    Walsh, Patrick S.; Kusaka, Ryoji; Zwier, Timothy S.; Fisher, Brian F.; Gellman, Samuel H.

    2013-06-01

    Spectroscopic studies of flexible peptides in the gas phase can provide insight to their inherent structural preferences in the absence of solvent. Recently, there has been increased attention paid to synthetic foldamers containing non-natural residues that can be specifically engineered to robustly form particular secondary structures. These engineered peptides have potential in therapeutic drug design because they are resistant to enzymatic degradation. Specifically, the Gellman group has synthesized a γ-peptide with a six membered cyclic constraint in the γ^{4}-γ^{3} position and an ethyl group at the γ^{2} position (γ_{ACHC}). The three stereocenters have a well-defined chirality [S,S,S]. These two features constrain the relative orientation of adjacent amide groups, thereby favoring a particular "pitch" to the turn. Solution phase results indicate that constrained γ-peptides induce the formation of a 14-helix. Ac-γ_{ACHC}-NHBz, its monohydrate and Ac-γ_{ACHC}-γ_{ACHC}-NHBz have been studied using ultraviolet (UV) and infrared (IR) double-resonance methods to obtain conformation-specific spectra under jet-cooled conditions in the gas phase. IR spectra in the hydride stretch (3300-3750 cm^{-1}), amide I/II and OH bend (1400-1800 cm^{-1}) were recorded and compared to predictions using density functional methods (DFT) and harmonic frequency calculations. We will compare the present results on constrained γ-peptides with corresponding results on unconstrained analogs. Data obtained for the monohydrated water cluster of Ac-γ_{ACHC}-NHBz will also be presented, including assignment of the water bend fundamental, which appears in the midst of transitions due to the amide II vibrations. L. Guo, W. Zhang, A. G. Reidenbach, M. W. Giuliano, I. A. Guzei, L. C. Spencer and S. H. Gellman Angew. Chem. Int. Ed. 2011, 50, 5843-5846

  10. The design and synthesis of hard and impermeable, yet flexible, conformal organic coatings.

    PubMed

    Xu, Jingjing; Asatekin, Ayse; Gleason, Karen K

    2012-07-17

    A new design paradigm for conformal, all-organic coatings that retain their flexibility and chemical functionality while displaying exceptional mechanical hardness and barrier properties is presented. Initiated chemical vapor deposition is used to synthesize a novel alternating copolymer thin film. Upon annealing, films display elastic moduli exceeding 20 GPa, excellent scratch resistance and flexibility, and very low oxygen permeability.

  11. Large area photonic flash soldering of thin chips on flex foils for flexible electronic systems: In situ temperature measurements and thermal modelling

    NASA Astrophysics Data System (ADS)

    van den Ende, D. A.; Hendriks, R.; Cauchois, R.; Groen, W. A.

    2014-11-01

    In this work photonic energy from a high power xenon flash lamp is used for soldering thin chips on polyimide and polyester foil substrates using standard Sn-Ag-Cu lead free alloys. The absorption of the xenon light pulse leads to rapid heating of components and tracks up to temperatures above the solder melting temperature, while the temperature in the organic foil substrates remains low. Due to its high transparency the temperature in the delicate polyester foil remains low enough to avoid damage and allows fast soldering with standard lead-free alloys. The technology is fast and could be applied in-line in roll-to-roll fabrication of flexible electronics. In situ temperature measurements were performed and compared to finite element model predictions of the temperature in the chip during and after application of the photonic pulse. The accuracy of the model is within 10°C for the tested samples, which allows it to be used in developing photonic flash soldering compatible circuit designs. [Figure not available: see fulltext.

  12. Ion Mobility Mass Spectrometry of a Rotary ATPase Reveals ATP-induced Reduction in Conformational Flexibility

    PubMed Central

    Davies, Roberta; Liko, Idlir; Wu, Kuan-Jung; Stewart, Alastair G.; Stock, Daniela; Robinson, Carol V.

    2014-01-01

    Rotary ATPases play fundamental roles in energy conversion, their catalytic rotation being associated with inter-domain fluctuations and heterogeneity of conformational states. Using ion mobility mass spectrometry (IM-MS) we compare the conformational dynamics of the intact ATPase from Thermus thermophilus (TtATPase) with its membrane and soluble subcomplexes. Our results define regions with enhanced flexibility assigned to distinct subunits within the overall assembly. To provide a structural context for our experimental data we performed molecular dynamics (MD) simulations and observed conformational changes of the peripheral stalks reflecting their intrinsic flexibility. By isolating complexes at different phases of cell growth and manipulating nucleotides, metal ions and pH during isolation, we reveal differences that can be related to conformational changes in the Vo complex, triggered by ATP binding. Together these results implicate nucleotides in modulating flexibility of the stator components and uncover mechanistic detail underlying operation and regulation in the context of the holo-enzyme. PMID:24557135

  13. Flexibility unleashed in acyclic monoterpenes: conformational space of citronellal revealed by broadband rotational spectroscopy.

    PubMed

    Domingos, Sérgio R; Pérez, Cristóbal; Medcraft, Chris; Pinacho, Pablo; Schnell, Melanie

    2016-06-22

    Conformational flexibility is intrinsically related to the functionality of biomolecules. Elucidation of the potential energy surface is thus a necessary step towards understanding the mechanisms for molecular recognition such as docking of small organic molecules to larger macromolecular systems. In this work, we use broadband rotational spectroscopy in a molecular jet experiment to unravel the complex conformational space of citronellal. We observe fifteen conformations in the experimental conditions of the molecular jet, the highest number of conformers reported to date for a chiral molecule of this size using microwave spectroscopy. Studies of relative stability using different carrier gases in the supersonic expansion reveal conformational relaxation pathways that strongly favour ground-state structures with globular conformations. This study provides a blueprint of the complex conformational space of an important biosynthetic precursor and gives insights on the relation between its structure and biological functionality.

  14. NMR observation of rotory conformers in flexible-chain polymers

    SciTech Connect

    Sadykov, R.K.; Makhiyanov, N.; Kurbatov, V.A.; Savel'ev, V.S.; Kirpichnikov, P.A.

    1987-08-01

    The authors conduct a comprehensive line analysis of the NMR spectra of a number of polymers, including cis-1,4-polyisoprenes, cis-1-4-polybutadiene, polyisobutylene, and polyethylene, in a deuterated benzene solvent. Data are given on hyperfine structure and spin-spin coupling constants along with conformational behavior and a negative Overhauser effect observed in the isomers.

  15. The Large Area Telescope

    SciTech Connect

    Michelson, Peter F.; /KIPAC, Menlo Park /Stanford U., HEPL

    2007-11-13

    The Large Area Telescope (LAT), one of two instruments on the Gamma-ray Large Area Space Telescope (GLAST) mission, is an imaging, wide field-of-view, high-energy pair-conversion telescope, covering the energy range from {approx}20 MeV to more than 300 GeV. The LAT is being built by an international collaboration with contributions from space agencies, high-energy particle physics institutes, and universities in France, Italy, Japan, Sweden, and the United States. The scientific objectives the LAT will address include resolving the high-energy gamma-ray sky and determining the nature of the unidentified gamma-ray sources and the origin of the apparently isotropic diffuse emission observed by EGRET; understanding the mechanisms of particle acceleration in celestial sources, including active galactic nuclei, pulsars, and supernovae remnants; studying the high-energy behavior of gamma-ray bursts and transients; using high-energy gamma-rays to probe the early universe to z {ge} 6; and probing the nature of dark matter. The components of the LAT include a precision silicon-strip detector tracker and a CsI(Tl) calorimeter, a segmented anticoincidence shield that covers the tracker array, and a programmable trigger and data acquisition system. The calorimeter's depth and segmentation enable the high-energy reach of the LAT and contribute significantly to background rejection. The aspect ratio of the tracker (height/width) is 0.4, allowing a large field-of-view and ensuring that nearly all pair-conversion showers initiated in the tracker will pass into the calorimeter for energy measurement. This paper includes a description of each of these LAT subsystems as well as a summary of the overall performance of the telescope.

  16. Flexible backbone sampling methods to model and design protein alternative conformations.

    PubMed

    Ollikainen, Noah; Smith, Colin A; Fraser, James S; Kortemme, Tanja

    2013-01-01

    Sampling alternative conformations is key to understanding how proteins work and engineering them for new functions. However, accurately characterizing and modeling protein conformational ensembles remain experimentally and computationally challenging. These challenges must be met before protein conformational heterogeneity can be exploited in protein engineering and design. Here, as a stepping stone, we describe methods to detect alternative conformations in proteins and strategies to model these near-native conformational changes based on backrub-type Monte Carlo moves in Rosetta. We illustrate how Rosetta simulations that apply backrub moves improve modeling of point mutant side-chain conformations, native side-chain conformational heterogeneity, functional conformational changes, tolerated sequence space, protein interaction specificity, and amino acid covariation across protein-protein interfaces. We include relevant Rosetta command lines and RosettaScripts to encourage the application of these types of simulations to other systems. Our work highlights that critical scoring and sampling improvements will be necessary to approximate conformational landscapes. Challenges for the future development of these methods include modeling conformational changes that propagate away from designed mutation sites and modulating backbone flexibility to predictively design functionally important conformational heterogeneity.

  17. Large area Czochralski silicon

    NASA Technical Reports Server (NTRS)

    Rea, S. N.; Gleim, P. S.

    1977-01-01

    The overall cost effectiveness of the Czochralski process for producing large-area silicon was determined. The feasibility of growing several 12 cm diameter crystals sequentially at 12 cm/h during a furnace run and the subsequent slicing of the ingot using a multiblade slurry saw were investigated. The goal of the wafering process was a slice thickness of 0.25 mm with minimal kerf. A slice + kerf of 0.56 mm was achieved on 12 cm crystal using both 400 grit B4C and SiC abrasive slurries. Crystal growth experiments were performed at 12 cm diameter in a commercially available puller with both 10 and 12 kg melts. Several modifications to the puller hoz zone were required to achieve stable crystal growth over the entire crystal length and to prevent crystallinity loss a few centimeters down the crystal. The maximum practical growth rate for 12 cm crystal in this puller design was 10 cm/h, with 12 to 14 cm/h being the absolute maximum range at which melt freeze occurred.

  18. A Structure-free Method for Quantifying Conformational Flexibility in proteins

    PubMed Central

    Burger, Virginia M.; Arenas, Daniel J.; Stultz, Collin M.

    2016-01-01

    All proteins sample a range of conformations at physiologic temperatures and this inherent flexibility enables them to carry out their prescribed functions. A comprehensive understanding of protein function therefore entails a characterization of protein flexibility. Here we describe a novel approach for quantifying a protein’s flexibility in solution using small-angle X-ray scattering (SAXS) data. The method calculates an effective entropy that quantifies the diversity of radii of gyration that a protein can adopt in solution and does not require the explicit generation of structural ensembles to garner insights into protein flexibility. Application of this structure-free approach to over 200 experimental datasets demonstrates that the methodology can quantify a protein’s disorder as well as the effects of ligand binding on protein flexibility. Such quantitative descriptions of protein flexibility form the basis of a rigorous taxonomy for the description and classification of protein structure. PMID:27358108

  19. Delineating the conformational flexibility of trisaccharides from NMR spectroscopy experiments and computer simulations.

    PubMed

    Yang, Mingjun; Angles d'Ortoli, Thibault; Säwén, Elin; Jana, Madhurima; Widmalm, Göran; MacKerell, Alexander D

    2016-07-28

    The conformation of saccharides in solution is challenging to characterize in the context of a single well-defined three-dimensional structure. Instead, they are better represented by an ensemble of conformations associated with their structural diversity and flexibility. In this study, we delineate the conformational heterogeneity of five trisaccharides via a combination of experimental and computational techniques. Experimental NMR measurements target conformationally sensitive parameters, including J couplings and effective distances around the glycosidic linkages, while the computational simulations apply the well-calibrated additive CHARMM carbohydrate force field in combination with efficient enhanced sampling molecular dynamics simulation methods. Analysis of conformational heterogeneity is performed based on sampling of discreet states as defined by dihedral angles, on root-mean-square differences of Cartesian coordinates and on the extent of volume sampled. Conformational clustering, based on the glycosidic linkage dihedral angles, shows that accounting for the full range of sampled conformations is required to reproduce the experimental data, emphasizing the utility of the molecular simulations in obtaining an atomic detailed description of the conformational properties of the saccharides. Results show the presence of differential conformational preferences as a function of primary sequence and glycosidic linkage types. Significant differences in conformational ensembles associated with the anomeric configuration of a single glycosidic linkage reinforce the impact of such changes on the conformational properties of carbohydrates. The present structural insights of the studied trisaccharides represent a foundation for understanding the range of conformations adopted in larger oligosaccharides and how these molecules encode their conformational heterogeneity into the monosaccharide sequence. PMID:27346493

  20. Inspection des pieces flexibles sans gabarit de conformation

    NASA Astrophysics Data System (ADS)

    Aidibe, Ali

    In this thesis, we focus on the automation of the fixtureless geometric inspection of non-rigid (or compliant) parts. The primary objective of this project is to handle virtually this type of component and their point cloud, which represents a scan taken in a Free State condition, by eliminating the use of very expensive and complicated specialized fixtures posing productivity problems for manufacturing companies. This topic is a very high interest in the transport sector and, more specifically, in the aerospace one in order to significantly improve its productivity and its degree of competitiveness. The thesis is organized by articles. The study is divided over four phases. The first three phases will be represented by three journal papers and the fourth phase is presented as an appendix. The first phase of this work is intended to improve the identification module of an existing inspection mathematical tool " IDI: The Iterative Displacement Inspection " which has been developed by the research team working under the supervision of professor Tahan at ETS. The identification module aims to distinguish between defects that are due to the manufacturing process and deformations that are due to the flexibility of the part (gravity and residual stress effects). We propose to replace the original module with a new one which is based on the extreme value statistical analysis. We demonstrate that the new module remarkably reduces the type I and type II errors. In addition, unlike the identification method of the IDI, the proposed one does not require a user-specified threshold based on a trial and error process. In the second phase of this study, we propose an original approach to measure the flexibility/rigidity of the mechanical components. We introduce a factor that represents the ratio between the maximum displacement resulting from the deformation of the part and its profile tolerance and we present the results in a logarithmic scale. Three different regions were

  1. Assessment of the trackability, flexibility, and conformability of coronary stents: a comparative analysis.

    PubMed

    Rieu, Régis; Barragan, Paul; Garitey, Vincent; Roquebert, Pierre O; Fuseri, Jean; Commeau, Philippe; Sainsous, Joel

    2003-08-01

    The efficacy and safety of coronary stent implantation depend on the mechanical features of these devices when deployed in atheromatous lesions of various morphologies. We evaluated the trackability, flexibility, and conformability of 17 coronary stents using specific mechanical bench tests. The quantifications used a dynamometer for assessment of trackability (maximal strength) and flexibility (stiffness) and a 3D optical gauging machine for assessment of conformability (distance between stent and arterial wall in a curvature). The maximal strength (measuring the trackability) ranged respectively from 0.24 +/- 0.06 and 0.38 +/- 0.03 N (Seaquest) to 1.31 +/- 0.42 and 1.34 +/- 0.35 N (Carbostent), concerning respectively curvatures of 90 degrees (P < 0.0001) and 135 degrees (P < 0.0001). The stiffness (measuring the flexibility) ranged from 0.53 +/- 0.16 (Seaquest) to 1.28 +/- 0.10 N/mm (NIR Royal; P < 0.0001). The mean distance between stent and external curvature (external conformability) ranged from 0.15 +/- 0.06 mm (S7) to 0.57 +/- 0.4 mm (NIR Royal; P < 0.0001). The mean distance between stent and internal curve (internal conformability) ranged from 0.26 +/- 0.13 (S7) to 0.44 +/- 0.12 mm (S670; P < 0.0001). These results may influence the choice of a particular stent adapted to a specific coronary anatomy. PMID:12891615

  2. Probing flexible conformations in molecular junctions by inelastic electron tunneling spectroscopy

    SciTech Connect

    Deng, Mingsen; Ye, Gui; Jiang, Jun; Cai, Shaohong; Sun, Guangyu

    2015-01-15

    The probe of flexible molecular conformation is crucial for the electric application of molecular systems. We have developed a theoretical procedure to analyze the couplings of molecular local vibrations with the electron transportation process, which enables us to evaluate the structural fingerprints of some vibrational modes in the inelastic electron tunneling spectroscopy (IETS). Based on a model molecule of Bis-(4-mercaptophenyl)-ether with a flexible center angle, we have revealed and validated a simple mathematical relationship between IETS signals and molecular angles. Our results might open a route to quantitatively measure key geometrical parameters of molecular junctions, which helps to achieve precise control of molecular devices.

  3. Structure of a mutant [beta] toxin from Staphylococcus aureus reveals domain swapping and conformational flexibility

    SciTech Connect

    Kruse, Andrew C.; Huseby, Medora J.; Shi, Ke; Digre, Jeff; Ohlendorf, Douglas H.; Earhart, Cathleen A.

    2011-09-16

    The 3.35 {angstrom} resolution crystal structure of a mutant form of the staphylococcal sphingomyelinase {beta} toxin in which a conserved hydrophobic {beta}-hairpin has been deleted is reported. It is shown that this mutation induces domain swapping of a C-terminal {beta}-strand, leading to the formation of dimers linked by a conformationally flexible hinge region. Eight dimers are seen in the asymmetric unit, exhibiting a broad spectrum of conformations trapped in place by intermolecular contacts within the crystal lattice. Furthermore, the 16 monomers within each asymmetric unit exhibit a remarkable heterogeneity in thermal factors, which can be accounted for by the varying degrees to which each monomer interacts with other molecules in the crystal. This structure provides a unique example of the challenges associated with crystallographic study of flexible proteins.

  4. Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces

    NASA Astrophysics Data System (ADS)

    Kamali, Seyedeh Mahsa; Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei

    2016-05-01

    Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics or aesthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify near-infrared (λ=915 nm) optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept is highly versatile for developing arbitrarily shaped multi-functional optical devices.

  5. Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces.

    PubMed

    Kamali, Seyedeh Mahsa; Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei

    2016-01-01

    Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics or aesthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify near-infrared (λ=915 nm) optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept is highly versatile for developing arbitrarily shaped multi-functional optical devices. PMID:27193141

  6. Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces

    DOE PAGESBeta

    Kamali, Seyedeh Mahsa; Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei

    2016-05-19

    Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point and arbitrarily shaped objects introduce optical aberrations. Multifunctional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics or aesthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymermore » substrate that locally modify near-infrared (λ = 915 nm) optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. Lastly, the conformal metasurface concept is highly versatile for developing arbitrarily shaped multi-functional optical devices.« less

  7. Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces

    PubMed Central

    Kamali, Seyedeh Mahsa; Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei

    2016-01-01

    Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics or aesthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify near-infrared (λ=915 nm) optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept is highly versatile for developing arbitrarily shaped multi-functional optical devices. PMID:27193141

  8. Conformational flexibility of BECN1: Essential to its key role in autophagy and beyond.

    PubMed

    Mei, Yang; Glover, Karen; Su, Minfei; Sinha, Sangita C

    2016-10-01

    BECN1 (Beclin 1), a highly conserved eukaryotic protein, is a key regulator of autophagy, a cellular homeostasis pathway, and also participates in vacuolar protein sorting, endocytic trafficking, and apoptosis. BECN1 is important for embryonic development, the innate immune response, tumor suppression, and protection against neurodegenerative disorders, diabetes, and heart disease. BECN1 mediates autophagy as a core component of the class III phosphatidylinositol 3-kinase complexes. However, the exact mechanism by which it regulates the activity of these complexes, or mediates its other diverse functions is unclear. BECN1 interacts with several diverse protein partners, perhaps serving as a scaffold or interaction hub for autophagy. Based on extensive structural, biophysical and bioinformatics analyses, BECN1 consists of an intrinsically disordered region (IDR), which includes a BH3 homology domain (BH3D); a flexible helical domain (FHD); a coiled-coil domain (CCD); and a β-α-repeated autophagy-specific domain (BARAD). Each of these BECN1 domains mediates multiple diverse interactions that involve concomitant conformational changes. Thus, BECN1 conformational flexibility likely plays a key role in facilitating diverse protein interactions. Further, BECN1 conformation and interactions are also modulated by numerous post-translational modifications. A better structure-based understanding of the interplay between different BECN1 conformational and binding states, and the impact of post-translational modifications will be essential to elucidating the mechanism of its multiple biological roles.

  9. Evaluation of flexible and rigid (class solution) radiation therapy conformal prostate planning protocols

    SciTech Connect

    Coburn, Natalie; Beldham-Collins, Rachael; Westling, Jelene; Trovato, Jenny; Gebski, Val

    2012-04-01

    Protocols commonly implemented in radiotherapy work areas may be classified as being either rigid (class solution) or flexible. Because formal evaluation of these protocol types has not occurred within the literature, we evaluated the efficiency of a rigid compared with flexible prostate planning protocol by assessing a series of completed 3D conformal prostate plans. Twenty prostate cancer patients with an average age of 70 years (range, 52-77) and sizes comprising 8 small, 10 medium, and 2 large were planned on the Phillips Pinnacle treatment planning system 6 times by radiation therapists with <2 years, 2-5 years, and >5 years of experience using a rigid and flexible protocol. Plans were critiqued using critical organ doses, confirmation numbers, and conformity index. Plans were then classified as being acceptable or not. Plans produced with the flexible protocol were 53% less likely to require modification (OR 0.47, 95% CI: 0.26, 0.84, p = 0.01). Planners with >5 years of experience were 78% more likely to produce plans requiring modification (OR 1.78, 95% CI: 1.12, 2.83, P = 0.02). Plans according to the flexible protocol took longer (112 min) compared with the time taken using a rigid protocol (68 min) (p < 0.001). The results suggest that further studies are needed; however, we propose that all radiation therapy planners should start with the same limitations, and if an acceptable plan is not reached, then flexibility should be given to improve the plan to meet the desired results.

  10. Ultraflexible, large-area, physiological temperature sensors for multipoint measurements

    PubMed Central

    Yokota, Tomoyuki; Inoue, Yusuke; Terakawa, Yuki; Reeder, Jonathan; Kaltenbrunner, Martin; Ware, Taylor; Yang, Kejia; Mabuchi, Kunihiko; Murakawa, Tomohiro; Sekino, Masaki; Voit, Walter; Sekitani, Tsuyoshi; Someya, Takao

    2015-01-01

    We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 µm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25 °C and 50 °C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1 °C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature. PMID:26554008

  11. Buckling assisted and lithographically micropatterned fully flexible sensors for conformal integration applications.

    PubMed

    Maji, Debashis; Das, Debanjan; Wala, Jyoti; Das, Soumen

    2015-12-07

    Development of flexible sensors/electronics over substrates thicker than 100 μm is of immense importance for its practical feasibility. However, unlike over ultrathin films, large bending stress hinders its flexibility. Here we have employed a novel technique of fabricating sensors over a non-planar ridge topology under pre-stretched condition which not only helps in spontaneous generation of large and uniform parallel buckles upon release, but also acts as stress reduction zones thereby preventing Poisson's ratio induced lateral cracking. Further, we propose a complete lithography compatible process to realize flexible sensors over pre-stretched substrates thicker than 100 μm that are released through dissolution of a water soluble sacrificial layer of polyvinyl alcohol. These buckling assisted flexible sensors demonstrated superior performance along different flexible modalities. Based on the above concept, we also realized a micro thermal flow sensor, conformally wrapped around angiographic catheters to detect flow abnormalities for potential applications in interventional catheterization process.

  12. Buckling assisted and lithographically micropatterned fully flexible sensors for conformal integration applications

    PubMed Central

    Maji, Debashis; Das, Debanjan; Wala, Jyoti; Das, Soumen

    2015-01-01

    Development of flexible sensors/electronics over substrates thicker than 100 μm is of immense importance for its practical feasibility. However, unlike over ultrathin films, large bending stress hinders its flexibility. Here we have employed a novel technique of fabricating sensors over a non-planar ridge topology under pre-stretched condition which not only helps in spontaneous generation of large and uniform parallel buckles upon release, but also acts as stress reduction zones thereby preventing Poisson’s ratio induced lateral cracking. Further, we propose a complete lithography compatible process to realize flexible sensors over pre-stretched substrates thicker than 100 μm that are released through dissolution of a water soluble sacrificial layer of polyvinyl alcohol. These buckling assisted flexible sensors demonstrated superior performance along different flexible modalities. Based on the above concept, we also realized a micro thermal flow sensor, conformally wrapped around angiographic catheters to detect flow abnormalities for potential applications in interventional catheterization process. PMID:26640124

  13. Buckling assisted and lithographically micropatterned fully flexible sensors for conformal integration applications

    NASA Astrophysics Data System (ADS)

    Maji, Debashis; Das, Debanjan; Wala, Jyoti; Das, Soumen

    2015-12-01

    Development of flexible sensors/electronics over substrates thicker than 100 μm is of immense importance for its practical feasibility. However, unlike over ultrathin films, large bending stress hinders its flexibility. Here we have employed a novel technique of fabricating sensors over a non-planar ridge topology under pre-stretched condition which not only helps in spontaneous generation of large and uniform parallel buckles upon release, but also acts as stress reduction zones thereby preventing Poisson’s ratio induced lateral cracking. Further, we propose a complete lithography compatible process to realize flexible sensors over pre-stretched substrates thicker than 100 μm that are released through dissolution of a water soluble sacrificial layer of polyvinyl alcohol. These buckling assisted flexible sensors demonstrated superior performance along different flexible modalities. Based on the above concept, we also realized a micro thermal flow sensor, conformally wrapped around angiographic catheters to detect flow abnormalities for potential applications in interventional catheterization process.

  14. Ion mobility-mass spectrometry reveals conformational flexibility in the deubiquitinating enzyme USP5.

    PubMed

    Scott, Daniel; Layfield, Robert; Oldham, Neil J

    2015-08-01

    Many proteins exhibit conformation flexibility as part of their biological function, whether through the presence of a series of well-defined states or by the existence of intrinsic disorder. Ion mobility spectrometry, in combination with MS (IM-MS), offers a rapid and sensitive means of probing ensembles of protein structures through measurement of gas-phase collisional cross sections. We have applied IM-MS analysis to the multidomain deubiquitinating enzyme ubiquitin specific protease 5 (USP5), which is believed to exhibit significant conformational flexibility. Native ESI-MS measurement of the 94-kDa USP5 revealed two distinct charge-state distributions: [M + 17H](+) to [M + 21H](+) and [M + 24H](+) to [M + 29H](+). The collisional cross sections of these ions revealed clear groupings of 52 ± 4 nm(2) for the lower charges and 66 ± 6 nm(2) for the higher charges. Molecular dynamics simulation of a compact form of USP5, based on a crystal structure, produced structures of 53-54 nm(2) following 2 ns in the gas phase, while simulation of an extended form (based on small-angle X-ray scattering data) led to structures of 64 nm(2). These data demonstrate that IM-MS is a valuable tool in studying proteins with different discrete conformational states.

  15. Structural Flexibility and Conformation Features of Cyclic Dinucleotides in Aqueous Solutions.

    PubMed

    Che, Xing; Zhang, Jun; Zhu, Yanyu; Yang, Lijiang; Quan, Hui; Gao, Yi Qin

    2016-03-17

    Cyclic dinucleotides are able to trigger the innate immune system by activating STING. It was found that the binding affinity of asymmetric 2'3'-cGAMP to symmetric dimer of STING is 3 orders of magnitude higher than that of the symmetric 3'3'-cyclic dinucleotides. Such a phenomenon has not been understood yet. Here we show that the subtle changes in phosphodiester linkage of CDNs lead to their distinct structural properties which correspond to the varied binding affinities. 2'-5' and/or 3'-5' linked CDNs adopt specific while different types of ribose puckers and backbone conformations. That ribose conformations and base types have different propensities for anti or syn glycosidic conformations further affects the overall flexibility of CDNs. The counterbalance between backbone ring tension and electrostatic repulsion, both affected by the ring size, also contributes to the different flexibility of CDNs. Our calculations reveal that the free energy cost for 2'3'-cGAMP to adopt the STING-bound structure is smaller than that for 3'3'-cGAMP and cyclic-di-GMP. These findings may serve as a reference for design of CDN-analogues as vaccine adjuvants. Moreover, the cyclization pattern of CDNs closely related to their physiological roles suggests the importance of understanding structural properties in the study of protein-ligand interactions.

  16. Conformational flexibility and subunit arrangement of the modular yeast Spt-Ada-Gcn5 acetyltransferase complex.

    PubMed

    Setiaputra, Dheva; Ross, James D; Lu, Shan; Cheng, Derrick T; Dong, Meng-Qiu; Yip, Calvin K

    2015-04-17

    The Spt-Ada-Gcn5 acetyltransferase (SAGA) complex is a highly conserved, 19-subunit histone acetyltransferase complex that activates transcription through acetylation and deubiquitination of nucleosomal histones in Saccharomyces cerevisiae. Because SAGA has been shown to display conformational variability, we applied gradient fixation to stabilize purified SAGA and systematically analyzed this flexibility using single-particle EM. Our two- and three-dimensional studies show that SAGA adopts three major conformations, and mutations of specific subunits affect the distribution among these. We also located the four functional modules of SAGA using electron microscopy-based labeling and transcriptional activator binding analyses and show that the acetyltransferase module is localized in the most mobile region of the complex. We further comprehensively mapped the subunit interconnectivity of SAGA using cross-linking mass spectrometry, revealing that the Spt and Taf subunits form the structural core of the complex. These results provide the necessary restraints for us to generate a model of the spatial arrangement of all SAGA subunits. According to this model, the chromatin-binding domains of SAGA are all clustered in one face of the complex that is highly flexible. Our results relate information of overall SAGA structure with detailed subunit level interactions, improving our understanding of its architecture and flexibility.

  17. Ensemble refinement shows conformational flexibility in crystal structures of human complement factor D

    SciTech Connect

    Forneris, Federico; Burnley, B. Tom; Gros, Piet

    2014-03-01

    Ensemble-refinement analysis of native and mutant factor D (FD) crystal structures indicates a dynamical transition in FD from a self-inhibited inactive conformation to a substrate-bound active conformation that is reminiscent of the allostery in thrombin. Comparison with previously observed dynamics in thrombin using NMR data supports the crystallographic ensembles. Human factor D (FD) is a self-inhibited thrombin-like serine proteinase that is critical for amplification of the complement immune response. FD is activated by its substrate through interactions outside the active site. The substrate-binding, or ‘exosite’, region displays a well defined and rigid conformation in FD. In contrast, remarkable flexibility is observed in thrombin and related proteinases, in which Na{sup +} and ligand binding is implied in allosteric regulation of enzymatic activity through protein dynamics. Here, ensemble refinement (ER) of FD and thrombin crystal structures is used to evaluate structure and dynamics simultaneously. A comparison with previously published NMR data for thrombin supports the ER analysis. The R202A FD variant has enhanced activity towards artificial peptides and simultaneously displays active and inactive conformations of the active site. ER revealed pronounced disorder in the exosite loops for this FD variant, reminiscent of thrombin in the absence of the stabilizing Na{sup +} ion. These data indicate that FD exhibits conformational dynamics like thrombin, but unlike in thrombin a mechanism has evolved in FD that locks the unbound native state into an ordered inactive conformation via the self-inhibitory loop. Thus, ensemble refinement of X-ray crystal structures may represent an approach alternative to spectroscopy to explore protein dynamics in atomic detail.

  18. Combining conformational flexibility and continuum electrostatics for calculating pK(a)s in proteins.

    PubMed Central

    Georgescu, Roxana E; Alexov, Emil G; Gunner, Marilyn R

    2002-01-01

    Protein stability and function relies on residues being in their appropriate ionization states at physiological pH. In situ residue pK(a)s also provides a sensitive measure of the local protein environment. Multiconformation continuum electrostatics (MCCE) combines continuum electrostatics and molecular mechanics force fields in Monte Carlo sampling to simultaneously calculate side chain ionization and conformation. The response of protein to charges is incorporated both in the protein dielectric constant (epsilon(prot)) of four and by explicit conformational changes. The pK(a) of 166 residues in 12 proteins was determined. The root mean square error is 0.83 pH units, and >90% have errors of <1 pH units whereas only 3% have errors >2 pH units. Similar results are found with crystal and solution structures, showing that the method's explicit conformational sampling reduces sensitivity to the initial structure. The outcome also changes little with protein dielectric constant (epsilon(prot) 4-20). Multiconformation continuum electrostatics titrations show coupling of conformational flexibility and changes in ionization state. Examples are provided where ionizable side chain position (protein G), Asn orientation (lysozyme), His tautomer distribution (RNase A), and phosphate ion binding (RNase A and H) change with pH. Disallowing these motions changes the calculated pK(a). PMID:12324397

  19. Flexible polyelectrolyte conformation in the presence of cationic and anionic surfactants

    NASA Astrophysics Data System (ADS)

    Passos, C. B.; Kuhn, P. S.; Diehl, A.

    2015-11-01

    In this work we have studied the conformation of flexible polyelectrolyte chains in the presence of cationic and anionic surfactant molecules. We developed a simple theoretical model for the formation of the polyelectrolyte-cationic surfactant complexes and mixed micelles formed by cationic and anionic surfactant molecules, in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interaction included explicitly as an effective short-ranged attraction between the surfactant hydrocarbon tails. This simple model allows us to calculate the extension of the polyelectrolyte-cationic surfactant complexes as a function of the anionic surfactant concentration, for different types of cationic and anionic surfactant molecules. A discrete conformational transition from a collapsed state to an elongated coil was found, for all surfactant chain lengths we have considered, in agreement with the experimental observations for the unfolding of ​DNA-cationic surfactant complexes.

  20. 3D conformation of a flexible fiber in a turbulent flow

    NASA Astrophysics Data System (ADS)

    Verhille, Gautier; Bartoli, Adrien

    2016-07-01

    A growing number of studies is devoted to anisotropic particles in turbulent flows. In most cases, the particles are assumed to be rigid and their deformations are neglected. We present an adaptation of classical computer vision tools to reconstruct from two different images the 3D conformation of a fiber distorted by the turbulent fluctuations in a von Kármán flow. This technique allows us notably to characterize the fiber deformation by computing the correlation function of the orientation of the tangent vector. This function allows us to tackle the analogy between polymers and flexible fibers proposed by Brouzet et al. (Phys Rev Lett 112(7):074501, 2014). We show that this function depends on an elastic length ℓ _e which characterizes the particle flexibility, as is the case for polymers, but also on the fiber length L, contrary to polymers.

  1. Fermi's Large Area Telescope (LAT)

    NASA Video Gallery

    Fermi’s Large Area Telescope (LAT) is the spacecraft’s main scientificinstrument. This animation shows a gamma ray (purple) entering the LAT,where it is converted into an electron (red) and a...

  2. Step-Controllable Electric-Field-Assisted Nanoimprint Lithography for Uneven Large-Area Substrates.

    PubMed

    Wang, Chunhui; Shao, Jinyou; Tian, Hongmiao; Li, Xiangming; Ding, Yucheng; Li, Ben Q

    2016-04-26

    Large-area nanostructures are widely used in various fields, but fabrication on large-area uneven substrates poses a significant challenge. This study demonstrates a step-controllable electric-field-assisted nanoimprint lithography (e-NIL) method that can achieve conformal contact with uneven substrates for high fidelity nanostructuring. Experiments are used to demonstrate the method where a substrate coated with liquid resist is brought into contact with a flexible template driven by the applied electric field. Theoretical analysis based on the elasticity theory and electro-hydrodynamic theory is carried out. Effective voltage range and the saturation voltage are also discussed. A step-controllable release of flexible template is proposed and demonstrated to ensure the continuous contact between the template and an uneven substrate. This prevents formation of air traps and allows large area conformal contact to be achieved. A combination of Vacuum-electric field assisted step-controllable e-NIL is implemented in the developed prototype. Finally, photonic crystal nanostructures are successfully fabricated on a 4 in., 158 μm bow gallium nitride light-emitting diode epitaxial wafer using the proposed method, which enhance the light extraction property. PMID:27015525

  3. Ion mobility-mass spectrometry of a rotary ATPase reveals ATP-induced reduction in conformational flexibility

    NASA Astrophysics Data System (ADS)

    Zhou, Min; Politis, Argyris; Davies, Roberta B.; Liko, Idlir; Wu, Kuan-Jung; Stewart, Alastair G.; Stock, Daniela; Robinson, Carol V.

    2014-03-01

    Rotary ATPases play fundamental roles in energy conversion as their catalytic rotation is associated with interdomain fluctuations and heterogeneity of conformational states. Using ion mobility mass spectrometry we compared the conformational dynamics of the intact ATPase from Thermus thermophilus with those of its membrane and soluble subcomplexes. Our results define regions with enhanced flexibility assigned to distinct subunits within the overall assembly. To provide a structural context for our experimental data we performed molecular dynamics simulations and observed conformational changes of the peripheral stalks that reflect their intrinsic flexibility. By isolating complexes at different phases of cell growth and manipulating nucleotides, metal ions and pH during isolation, we reveal differences that can be related to conformational changes in the Vo complex triggered by ATP binding. Together these results implicate nucleotides in modulating flexibility of the stator components and uncover mechanistic detail that underlies operation and regulation in the context of the holoenzyme.

  4. Ion mobility-mass spectrometry of a rotary ATPase reveals ATP-induced reduction in conformational flexibility.

    PubMed

    Zhou, Min; Politis, Argyris; Davies, Roberta B; Liko, Idlir; Wu, Kuan-Jung; Stewart, Alastair G; Stock, Daniela; Robinson, Carol V

    2014-03-01

    Rotary ATPases play fundamental roles in energy conversion as their catalytic rotation is associated with interdomain fluctuations and heterogeneity of conformational states. Using ion mobility mass spectrometry we compared the conformational dynamics of the intact ATPase from Thermus thermophilus with those of its membrane and soluble subcomplexes. Our results define regions with enhanced flexibility assigned to distinct subunits within the overall assembly. To provide a structural context for our experimental data we performed molecular dynamics simulations and observed conformational changes of the peripheral stalks that reflect their intrinsic flexibility. By isolating complexes at different phases of cell growth and manipulating nucleotides, metal ions and pH during isolation, we reveal differences that can be related to conformational changes in the Vo complex triggered by ATP binding. Together these results implicate nucleotides in modulating flexibility of the stator components and uncover mechanistic detail that underlies operation and regulation in the context of the holoenzyme.

  5. Calcium Binding Promotes Conformational Flexibility of the Neuronal Ca2+ Sensor Synaptotagmin

    PubMed Central

    Bykhovskaia, Maria

    2015-01-01

    Synaptotagmin 1 (Syt1) is a synaptic vesicle protein that serves as a calcium sensor of neuronal secretion. It is established that calcium binding to Syt1 triggers vesicle fusion and release of neuronal transmitters, however, the dynamics of this process is not fully understood. To investigate how Ca2+ binding affects Syt1 conformational dynamics, we performed prolonged molecular dynamics (MD) simulations of Ca2+-unbound and Ca2+-bound forms of Syt1. MD simulations were performed at a microsecond scale and combined with Monte Carlo sampling. We found that in the absence of Ca2+ Syt1 structure in the solution is represented by an ensemble of conformational states with tightly coupled domains. To investigate the effect of Ca2+ binding, we used two different strategies to generate a molecular model of a Ca2+-bound form of Syt1. First, we employed subsequent replacements of monovalent cations transiently captured within Syt1 Ca2+-binding pockets by Ca2+ ions. Second, we performed MD simulations of Syt1 at elevated Ca2+ levels. All the simulations produced Syt1 structures bound to four Ca2+ ions, two ions chelated at the binding pocket of each domain. MD simulations of the Ca2+-bound form of Syt1 revealed that Syt1 conformational flexibility drastically increased upon Ca2+ binding. In the presence of Ca2+, the separation between domains increased, and interdomain rotations became more frequent. These findings suggest that Ca2+ binding to Syt1 may induce major changes in the Syt1 conformational state, which in turn may initiate the fusion process. PMID:25992729

  6. Glutamate Racemase Dimerization Inhibits Dynamic Conformational Flexibility and Reduces Catalytic Rates

    SciTech Connect

    Mehboob, Shahila; Guo, Liang; Fu, Wentao; Mittal, Anuradha; Yau, Tiffany; Truong, Kent; Johlfs, Mary; Long, Fei; Fung, Leslie W.-M.; Johnson, Michael E.

    2009-09-15

    Glutamate racemase (RacE) is a bacterial enzyme that converts L-glutamate to D-glutamate, an essential precursor for peptidoglycan synthesis. In prior work, we have shown that both isoforms cocrystallize with D-glutamate as dimers, and the enzyme is in a closed conformation with limited access to the active site [May, M., et al. (2007) J. Mol. Biol. 371, 1219-1237]. The active site of RacE2 is especially restricted. We utilize several computational and experimental approaches to understand the overall conformational dynamics involved during catalysis when the ligand enters and the product exits the active site. Our steered molecular dynamics simulations and normal-mode analysis results indicate that the monomeric form of the enzyme is more flexible than the native dimeric form. These results suggest that the monomeric enzyme might be more active than the dimeric form. We thus generated site-specific mutations that disrupt dimerization and find that the mutants exhibit significantly higher catalytic rates in the D-Glu to L-Glu reaction direction than the native enzyme. Low-resolution models restored from solution X-ray scattering studies correlate well with the first six normal modes of the dimeric form of the enzyme, obtained from NMA. Thus, along with the local active site residues, global domain motions appear to be implicated in the catalytically relevant structural dynamics of this enzyme and suggest that increased flexibility may accelerate catalysis. This is a novel observation that residues distant from the catalytic site restrain catalytic activity through formation of the dimer structure.

  7. Conformational flexibility of RecA protein filament: transitions between compressed and stretched states.

    PubMed

    Petukhov, Michael; Lebedev, Dmitry; Shalguev, Valery; Islamov, Akhmed; Kuklin, Aleksandr; Lanzov, Vladislav; Isaev-Ivanov, Vladimir

    2006-11-01

    RecA protein is a central enzyme in homologous DNA recombination, repair and other forms of DNA metabolism in bacteria. It functions as a flexible helix-shaped filament bound on stretched single-stranded or double-stranded DNA in the presence of ATP. In this work, we present an atomic level model for conformational transitions of the RecA filament. The model describes small movements of the RecA N-terminal domain due to coordinated rotation of main chain dihedral angles of two amino acid residues (Psi/Lys23 and Phi/Gly24), while maintaining unchanged the RecA intersubunit interface. The model is able to reproduce a wide range of observed helix pitches in transitions between compressed and stretched conformations of the RecA filament. Predictions of the model are in agreement with Small Angle Neutron Scattering (SANS) measurements of the filament helix pitch in RecA::ADP-AlF(4) complex at various salt concentrations. PMID:16909421

  8. Investigation of the conformational flexibility of DGAT1 peptides using tryptophan fluorescence

    NASA Astrophysics Data System (ADS)

    Lopes, Jose L. S.; Araujo, Ana P. U.; Jameson, David M.

    2015-06-01

    The conformational behavior of synthetic peptides corresponding to the putative binding sites of the diacylglycerol acyltransferase 1 enzyme (a polytopic integral membrane protein) was investigated using steady-state and time-resolved fluorescence spectroscopies. Three small linear peptides with 13, 15 and 22 amino acid residues, containing one, two and three Trp residues, respectively, were studied in aqueous solution, in the absence and presence of model membranes. The high flexibility and unordered conformation of the peptides in solution were confirmed by the low Trp polarization values, the high accessibility to water-soluble quencher, and the fast rotational correlation times of the Trp residues. However, upon binding to the lipid systems, the Trp residues were incorporated within the acyl hydrophobic core and their lifetimes and rotational correlation times increased. Phasor plots were employed to analyze intensity decay of peptide-lipid binding and provided a trajectory, in phasor space, that lies along a line connecting the points of the free and bound peptide. This trajectory was analyzed to determine the association constant of the peptide to the model membrane.

  9. How Conformational Flexibility Stabilizes the Hyperthermophilic Elongation Factor G-domain

    PubMed Central

    Kalimeri, Maria; Rahaman, Obaidur; Melchionna, Simone; Sterpone, Fabio

    2014-01-01

    Proteins from thermophilic organisms are stable and functional well above ambient temperature. Understanding the molecular mechanism underlying such a resistance is of crucial interest for many technological applications. For some time, thermal stability has been assumed to correlate with high mechanical rigidity of the protein matrix. In this work we address this common belief by carefully studying a pair of homologous G-domain proteins, with their melting temperatures differing by 40 K. To probe the thermal-stability content of the two proteins we use extensive simulations covering the microsecond time range and employ several different indicators to assess the salient features of the conformational landscape and the role of internal fluctuations at ambient condition. At the atomistic level, while the magnitude of fluctuations is comparable, the distribution of flexible and rigid stretches of amino-acids is more regular in the thermophilic protein causing a cage-like correlation of amplitudes along the sequence. This caging effect is suggested to favor stability at high T by confining the mechanical excitations. Moreover, it is found that the thermophilic protein, when folded, visits a higher number of conformational substates than the mesophilic homologue. The entropy associated with the occupation of the different substates, along with the thermal resilience of the protein intrinsic compressibility, provide a qualitative insight on the thermal stability of the thermophilic protein as compared to its mesophilic homologue. Our findings potentially open the route to new strategies in the design of thermostable proteins. PMID:24087838

  10. Multiple disulfide bridges modulate conformational stability and flexibility in hyperthermophilic archaeal purine nucleoside phosphorylase.

    PubMed

    Bagarolo, Maria Libera; Porcelli, Marina; Martino, Elisa; Feller, Georges; Cacciapuoti, Giovanna

    2015-10-01

    5'-Deoxy-5'-methylthioadenosine phosphorylase from Sulfolobus solfataricus is a hexameric hyperthermophilic protein containing in each subunit two pairs of disulfide bridges, a CXC motif, and one free cysteine. The contribution of each disulfide bridge to the protein conformational stability and flexibility has been assessed by comparing the thermal unfolding and the limited proteolysis of the wild-type enzyme and its variants obtained by site-directed mutagenesis of the seven cysteine residues. All variants catalyzed efficiently MTA cleavage with specific activity similar to the wild-type enzyme. The elimination of all cysteine residues caused a substantial decrease of ΔHcal (850 kcal/mol) and Tmax (39°C) with respect to the wild-type indicating that all cysteine pairs and especially the CXC motif significantly contribute to the enzyme thermal stability. Disulfide bond Cys200-Cys262 and the CXC motif weakly affected protein flexibility while the elimination of the disulfide bond Cys138-Cys205 lead to an increased protease susceptibility. Experimental evidence from limited proteolysis, differential scanning calorimetry, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions also allowed to propose a stabilizing role for the free Cys164.

  11. Large Area Vacuum Deposited Coatings

    SciTech Connect

    Martin, Peter M.

    2003-04-30

    It's easy to make the myriad of types of large area and decorative coatings for granted. We probably don't even think about most of them; the low-e and heat mirror coatings on our windows and car windows, the mirrors in displays, antireflection coatings on windows and displays, protective coatings on aircraft windows, heater coatings on windshields and aircraft windows, solar reflectors, thin film solar cells, telescope mirrors, Hubble mirrors, transparent conductive coatings, and the list goes on. All these products require large deposition systems and chambers. Also, don't forget that large batches of small substrates or parts are coated in large chambers. In order to be cost effective hundreds of ophthalmic lenses, automobile reflectors, display screens, lamp reflectors, cell phone windows, laser reflectors, DWDM filters, are coated in batches.

  12. Biophysical exploration of protein-flavonol recognition: effects of molecular properties and conformational flexibility.

    PubMed

    Ding, Fei; Peng, Wei; Peng, Yu-Kui

    2016-04-28

    The current work explores the biomolecular recognition of a series of flavonols by a protein and then uncovers the influences of the structural features of flavonols and the protein's own characteristics, e.g. the dynamics and flexibility, on the bioavailability of flavonols by using the pivotal biomacromolecule hemoglobin as a model. The experimental results revealed that flavonol may lead to a notable decrease in the steady-state fluorescence intensity of the β-37 Trp residue, and in the meantime the R-T transition of the protein transpired. Such noncovalent recognition forms the ground-state adduct, with an association intensity of 3.991 × 10(4) M(-1) in the reaction process, which has already been authenticated by the detailed analysis of time-resolved fluorescence and UV/vis absorption spectra. Furthermore, flavonol can form hydrogen bonds and π-conjugation effects with several amino acid residues on the polypeptide chain, for example, Trp-37, Arg-40, Asp-99 and Asn-102, and this event would induce self-regulation of the compact, regular conformation of the protein to a certain extent, which explicitly corroborates the results of circular dichroism. According to the study of molecular docking and structure-activity relationships, we could see that the recognition capacities of the protein-flavonols are inversely interrelated with the C log P values of the flavonol molecules. Moreover, the properties of the substituents in the structural B-ring unit of flavonols, i.e. polarity, position and number, will also prominently affect the degree of affinity and bioavailability of the protein-flavonol complexes. The analytical results of molecular dynamics (MD) simulation testified that the discussions of the structure-activity relationships are entirely logical, and the conformations of the amino acid residues forming noncovalent interactions tend to be stable in the MD simulation, as further elucidated from the dynamics data. Plainly, molecular recognition of

  13. pH-dependent conformational flexibility within the ribosomal peptidyl transferase center.

    PubMed Central

    Muth, G W; Chen, L; Kosek, A B; Strobel, S A

    2001-01-01

    A universally conserved adenosine, A2451, within the ribosomal peptidyl transferase center has been proposed to act as a general acid-base catalyst during peptide bond formation. Evidence in support of this proposal came from pH-dependent dimethylsulfate (DMS) modification within Escherichia coli ribosomes. A2451 displayed reactivity consistent with an apparent acidity constant (pKa) near neutrality, though pH-dependent structural flexibility could not be rigorously excluded as an explanation for the enhanced reactivity at high pH. Here we present three independent lines of evidence in support of the alternative interpretation. First, A2451 in ribosomes from the archaebacteria Haloarcula marismortui displays an inverted pH profile that is inconsistent with proton-mediated base protection. Second, in ribosomes from the yeast Saccharomyces cerevisiae, C2452 rather than A2451 is modified in a pH-dependent manner. Third, within E. coli ribosomes, the position of A2451 modification (N1 or N3 imino group) was analyzed by testing for a Dimroth rearrangement of the N1-methylated base. The data are more consistent with DMS modification of the A2451 N1, a functional group that, according to the 50S ribosomal crystal structure, is solvent inaccessible without structural rearrangement. It therefore appears that pH-dependent DMS modification of A2451 does not provide evidence either for or against a general acid-base mechanism of protein synthesis. Instead the data suggest that there is pH-dependent conformational flexibility within the peptidyl transferase center, the exact nature and physiological relevance of which is not known. PMID:11680845

  14. Quantitative structure-activity relationships for polychlorinated hydroxybiphenyl estrogen receptor binding affinity: An assessment of conformer flexibility

    SciTech Connect

    Bradbury, S.P.; Ankley, G.T.; Mekenyan, O.G.

    1996-11-01

    A diverse group of xenobiotics has a high binding affinity to the estrogen receptor (ER), suggesting that it can accommodate large variability in ligand structure. Relationships between xenobiotic surface, binding affinity, and estrogenic response have been suggested to be dependent on the conformational structures of the ligands. To explore the influence of conformational flexibility on ER binding affinity, a quantitative structure-activity relationship (QSAR) study was undertaken with estradiol, diethylstilbestrol, and a set of polychlorinated hydroxybiphenyls (PCHBs) of environmental concern. Although the low-energy minima of the PCHB congeners suggested that interconversions among conformers were likely, the electronic parameters associated with the conformer geometries for a specific PCHB congener could vary significantly. The results of the QSAR analysis suggested that among the PCHBs studied, the most polarizable conformers (lower absolute volume polarizability values) were most closely associated with ER binding affinity. Across the set of polarizable conformers, which did not include the low-energy gas-phase conformers, the electron donating properties of the hydroxy moiety and the aromatic component of the estradiol A ring analogue in the PCHBs were found to be correlated with higher ER binding affinity.

  15. Conformational flexibility around the Gal-β-(1 → 3)-Glc linkage: Experimental evidence for the existence of the anti-ψ conformation in aqueous solution.

    PubMed

    Vidal, Paloma; Jiménez-Barbero, Jesús; Espinosa, Juan F

    2016-10-01

    NOE-based analysis of the disaccharide β-Gal-(1 → 3)-β-Glc-OMe (1), especially a diagnostic Gal1-Glc4 NOE detected in a HSQC-NOESY spectrum, reveals the existence of the anti-ψ conformer in aqueous solution in addition to the major syn conformer. This result provides experimental proof of conformational flexibility around the aglyconic bond of β-(1 → 3) disaccharides, in contrast to previous studies that suggested that the flexibility around this linkage was restricted to the syn conformational region.

  16. An engineered scorpion toxin analogue with improved Kv1.3 selectivity displays reduced conformational flexibility

    PubMed Central

    Bartok, Adam; Fehér, Krisztina; Bodor, Andrea; Rákosi, Kinga; Tóth, Gábor K.; Kövér, Katalin E.; Panyi, Gyorgy; Varga, Zoltan

    2015-01-01

    The voltage-gated Kv1.3 K+ channel plays a key role in the activation of T lymphocytes. Kv1.3 blockers selectively suppress immune responses mediated by effector memory T cells, which indicates the great potential of selective Kv1.3 inhibitors in the therapy of certain autoimmune diseases. Anuroctoxin (AnTx), a 35-amino-acid scorpion toxin is a high affinity blocker of Kv1.3, but also blocks Kv1.2 with similar potency. We designed and produced three AnTx variants: ([F32T]-AnTx, [N17A]-AnTx, [N17A/F32T]-AnTx) using solid-phase synthesis with the goal of improving the selectivity of the toxin for Kv1.3 over Kv1.2 while keeping the high affinity for Kv1.3. We used the patch-clamp technique to determine the blocking potency of the synthetic toxins on hKv1.3, mKv1.1, hKv1.2 and hKCa3.1 channels. Of the three variants [N17A/F32T]-AnTx maintained the high affinity of the natural peptide for Kv1.3 but became more than 16000-fold selective over Kv1.2. NMR data and molecular dynamics simulations suggest that the more rigid structure with restricted conformational space of the double substituted toxin compared to the flexible wild-type one is an important determinant of toxin selectivity. Our results provide the foundation for the possibility of the production and future therapeutic application of additional, even more selective toxins targeting various ion channels. PMID:26689143

  17. The membrane anchor of the transcriptional activator SREBP is characterized by intrinsic conformational flexibility

    PubMed Central

    Linser, Rasmus; Salvi, Nicola; Briones, Rodolfo; Rovó, Petra; de Groot, Bert L.; Wagner, Gerhard

    2015-01-01

    Regulated intramembrane proteolysis (RIP) is a conserved mechanism crucial for numerous cellular processes, including signaling, transcriptional regulation, axon guidance, cell adhesion, cellular stress responses, and transmembrane protein fragment degradation. Importantly, it is relevant in various diseases including Alzheimer’s disease, cardiovascular diseases, and cancers. Even though a number of structures of different intramembrane proteases have been solved recently, fundamental questions concerning mechanistic underpinnings of RIP and therapeutic interventions remain. In particular, this includes substrate recognition, what properties render a given substrate amenable for RIP, and how the lipid environment affects the substrate cleavage. Members of the sterol regulatory element-binding protein (SREBP) family of transcription factors are critical regulators of genes involved in cholesterol/lipid homeostasis. After site-1 protease cleavage of the inactive SREBP transmembrane precursor protein, RIP of the anchor intermediate by site-2 protease generates the mature transcription factor. In this work, we have investigated the labile anchor intermediate of SREBP-1 using NMR spectroscopy. Surprisingly, NMR chemical shifts, site-resolved solvent exposure, and relaxation studies show that the cleavage site of the lipid-signaling protein intermediate bears rigid α-helical topology. An evolutionary conserved motif, by contrast, interrupts the secondary structure ∼9–10 residues C-terminal of the scissile bond and acts as an inducer of conformational flexibility within the carboxyl-terminal transmembrane region. These results are consistent with molecular dynamics simulations. Topology, stability, and site-resolved dynamics data suggest that the cleavage of the α-helical substrate in the case of RIP may be associated with a hinge motion triggered by the molecular environment. PMID:26392539

  18. Emulsifying and interfacial properties of vicilins: role of conformational flexibility at quaternary and/or tertiary levels.

    PubMed

    Liang, Han-Ni; Tang, Chuan-He

    2013-11-20

    Although the functionality of plant proteins (and soy proteins in particular) has been widely investigated in the last decades, the importance of conformational characteristics to their functionalities is still far away from being understood. The aim of the present work was to unravel the role of conformational flexibility at the quaternary and/or tertiary levels in the emulsifying and interfacial properties of phaseolin, an ideal vicilin (or 7S globulin) from red kidney bean. The conformational flexibility at quaternary and tertiary levels of phaseolin was modulated by urea with increasing concentrations from 0 to 8 M, as characterized by using dynamic light scattering (DLS), intrinsic fluorescence and derivative UV spectroscopy, and differential scanning calorimetry (DSC). The emulsifying and interfacial properties, including emulsifying ability, flocculated state of oil droplets (in fresh emulsions), emulsion stability against creaming, and adsorption dynamics at the oil-water interface, were characterized at a specific protein concentration of 0.5% (w/v). The results indicated that increasing the urea concentration resulted in a progressive dissociation of trimeric phaseolin molecules into monomeric subunits, and even a structural unfolding of dissociated subunits; the urea-induced conformational changes at quaternary and/or tertiary levels were reversible, and the molecules at high urea concentrations shared similar structural features to the "molten globule state". On the other hand, increasing the urea concentration progressively improved the emulsifying ability of the protein, and flocculated extent of oil droplets in the fresh emulsions, but led to a progressive decrease in interfacial protein concentration. The improvement of the emulsifying ability was not related to diffusion (during initial adsorption) and penetration at the interface, but highly dependent on ease of structural rearrangement of the adsorbed proteins. These observations clearly

  19. Atomic structure of recombinant thaumatin II reveals flexible conformations in two residues critical for sweetness and three consecutive glycine residues.

    PubMed

    Masuda, Tetsuya; Mikami, Bunzo; Tani, Fumito

    2014-11-01

    Thaumatin, an intensely sweet-tasting protein used as a sweetener, elicits a sweet taste at 50 nM. Although two major variants designated thaumatin I and thaumatin II exist in plants, there have been few dedicated thaumatin II structural studies and, to date, data beyond atomic resolution had not been obtained. To identify the detailed structural properties explaining why thaumatin elicits a sweet taste, the structure of recombinant thaumatin II was determined at the resolution of 0.99 Å. Atomic resolution structural analysis with riding hydrogen atoms illustrated the differences in the direction of the side-chains more precisely and the electron density maps of the C-terminal regions were markedly improved. Though it had been suggested that the three consecutive glycine residues (G142-G143-G144) have highly flexible conformations, G143, the central glycine residue was successfully modelled in two conformations for the first time. Furthermore, the side chain r.m.s.d. values for two residues (R67 and R82) critical for sweetness exhibited substantially higher values, suggesting that these residues are highly disordered. These results demonstrated that the flexible conformations in two critical residues favoring their interaction with sweet taste receptors are prominent features of the intensely sweet taste of thaumatin. PMID:25066915

  20. The statistical conformation of a highly flexible protein: Small angle X-ray scattering of S. aureus protein A

    PubMed Central

    Capp, Jo A.; Hagarman, Andrew; Richardson, David C.; Oas, Terrence G.

    2014-01-01

    Summary Staphylococcal protein A (SpA) is a multi-domain protein consisting of 5 globular IgG binding domains separated by a conserved 6 – 9 residue flexible linker. We collected SAXS data on the N-terminal protein-binding half of SpA (SpA-N) and constructs consisting of 1 – 5 domain modules in order to determine statistical conformation of this important S. aureus virulence factor. We fit the SAXS data to a scattering function based on a new polymer physics model, which provides an analytical description of the SpA-N statistical conformation. We describe a protocol for systematically determining the appropriate level of modeling to fit a SAXS dataset, based on goodness of fit and whether the addition of parameters improves it. In the case of SpA-N, the analytical polymer physics description provides a depiction of the statistical conformation of a flexible protein that, while lacking atomistic detail, properly reflects the information content of the data. PMID:25087509

  1. Atomic structure of recombinant thaumatin II reveals flexible conformations in two residues critical for sweetness and three consecutive glycine residues.

    PubMed

    Masuda, Tetsuya; Mikami, Bunzo; Tani, Fumito

    2014-11-01

    Thaumatin, an intensely sweet-tasting protein used as a sweetener, elicits a sweet taste at 50 nM. Although two major variants designated thaumatin I and thaumatin II exist in plants, there have been few dedicated thaumatin II structural studies and, to date, data beyond atomic resolution had not been obtained. To identify the detailed structural properties explaining why thaumatin elicits a sweet taste, the structure of recombinant thaumatin II was determined at the resolution of 0.99 Å. Atomic resolution structural analysis with riding hydrogen atoms illustrated the differences in the direction of the side-chains more precisely and the electron density maps of the C-terminal regions were markedly improved. Though it had been suggested that the three consecutive glycine residues (G142-G143-G144) have highly flexible conformations, G143, the central glycine residue was successfully modelled in two conformations for the first time. Furthermore, the side chain r.m.s.d. values for two residues (R67 and R82) critical for sweetness exhibited substantially higher values, suggesting that these residues are highly disordered. These results demonstrated that the flexible conformations in two critical residues favoring their interaction with sweet taste receptors are prominent features of the intensely sweet taste of thaumatin.

  2. Chimpanzees (Pan troglodytes) flexibly adjust their behaviour in order to maximize payoffs, not to conform to majorities.

    PubMed

    Van Leeuwen, Edwin J C; Cronin, Katherine A; Schütte, Sebastian; Call, Josep; Haun, Daniel B M

    2013-01-01

    Chimpanzees have been shown to be adept learners, both individually and socially. Yet, sometimes their conservative nature seems to hamper the flexible adoption of superior alternatives, even to the extent that they persist in using entirely ineffective strategies. In this study, we investigated chimpanzees' behavioural flexibility in two different conditions under which social animals have been predicted to abandon personal preferences and adopt alternative strategies: i) under influence of majority demonstrations (i.e. conformity), and ii) in the presence of superior reward contingencies (i.e. maximizing payoffs). Unlike previous nonhuman primate studies, this study disentangled the concept of conformity from the tendency to maintain one's first-learned strategy. Studying captive (n=16) and semi-wild (n=12) chimpanzees in two complementary exchange paradigms, we found that chimpanzees did not abandon their behaviour in order to match the majority, but instead remained faithful to their first-learned strategy (Study 1a and 1b). However, the chimpanzees' fidelity to their first-learned strategy was overridden by an experimental upgrade of the profitability of the alternative strategy (Study 2). We interpret our observations in terms of chimpanzees' relative weighing of behavioural options as a function of situation-specific trade-offs. More specifically, contrary to previous findings, chimpanzees in our study abandoned their familiar behaviour to maximize payoffs, but not to conform to a majority. PMID:24312252

  3. Solution conformation and flexibility of capsular polysaccharides from Neisseria meningitidis and glycoconjugates with the tetanus toxoid protein

    PubMed Central

    Abdelhameed, Ali Saber; Morris, Gordon A.; Almutairi, Fahad; Adams, Gary G.; Duvivier, Pierre; Conrath, Karel; Harding, Stephen E.

    2016-01-01

    The structural integrity of meningococcal native, micro-fluidized and activated capsular polysaccharides and their glycoconjugates – in the form most relevant to their potential use as vaccines (dilute solution) - have been investigated with respect to their homogeneity, conformation and flexibility. Sedimentation velocity analysis showed that the polysaccharide size distributions were generally bimodal with some evidence for higher molar mass forms at higher concentration. Weight average molar masses Mw where lower for activated polysaccharides. Conjugation with tetanus toxoid protein however greatly increased the molar mass and polydispersity of the final conjugates. Glycoconjugates had an approximately unimodal log-normal but broad and large molar mass profiles, confirmed by sedimentation equilibrium “SEDFIT MSTAR” analysis. Conformation analysis using HYDFIT (which globally combines sedimentation and viscosity data), “Conformation Zoning” and Wales-van Holde approaches showed a high degree of flexibility – at least as great as the unconjugated polysaccharides, and very different from the tetanus toxoid (TT) protein used for the conjugation. As with the recently published finding for Hib-TT complexes, it is the carbohydrate component that dictates the solution behaviour of these glycoconjugates, although the lower intrinsic viscosities suggest some degree of compaction of the carbohydrate chains around the protein. PMID:27782149

  4. Flexibility.

    ERIC Educational Resources Information Center

    Humphrey, L. Dennis

    1981-01-01

    Flexibility is an important aspect of all sports and recreational activities. Flexibility can be developed and maintained by stretching exercises. Exercises designed to develop flexibility in ankle joints, knees, hips, and the lower back are presented. (JN)

  5. Conformational flexibility of PPII-helix: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Guo, Ping; Lei, Xiaoling; Gao, Yi

    2016-05-01

    Poly-proline fragments form the distinctive PPII-helix in a high percentage in proteins and peptides, which plays an important role in signal transduction and protein complex assembly. But why and how this helical structure works is still unknown. In this work, we applied the density functional calculations to investigate the different preferences of prolines on Cγ-endo and Cγ-exo conformers, in which non-covalent interactions play important roles. As a result, Cγ-exo conformers are favored for short-oligomers with stronger n → π* interaction formed by the backbone, while Cγ-endo conformers are favored for longer oligomers with stronger dipole interactions between side groups.

  6. Conformational Flexibility in the Flap Domains of Ligand-Free HIV Protease

    SciTech Connect

    Heaslet, H.; Rosenfeld, R.; Giffin, M.; Lin, Y.-C.; Tam, K.; Torbett, B.E.; Elder, J.H.; Stout, C.D.

    2009-06-01

    The crystal structures of wild-type HIV protease (HIV PR) in the absence of substrate or inhibitor in two related crystal forms at 1.4 and 2.15 {angstrom} resolution are reported. In one crystal form HIV PR adopts an 'open' conformation with a 7.7 {angstrom} separation between the tips of the flaps in the homodimer. In the other crystal form the tips of the flaps are 'curled' towards the 80s loop, forming contacts across the local twofold axis. The 2.3 {angstrom} resolution crystal structure of a sixfold mutant of HIV PR in the absence of substrate or inhibitor is also reported. The mutant HIV PR, which evolved in response to treatment with the potent inhibitor TL-3, contains six point mutations relative to the wild-type enzyme (L24I, M46I, F53L, L63P, V77I, V82A). In this structure the flaps also adopt a 'curled' conformation, but are separated and not in contact. Comparison of the apo structures to those with TL-3 bound demonstrates the extent of conformational change induced by inhibitor binding, which includes reorganization of the packing between twofold-related flaps. Further comparison with six other apo HIV PR structures reveals that the 'open' and 'curled' conformations define two distinct families in HIV PR. These conformational states include hinge motion of residues at either end of the flaps, opening and closing the entire {beta}-loop, and translational motion of the flap normal to the dimer twofold axis and relative to the 80s loop. The alternate conformations also entail changes in the {beta}-turn at the tip of the flap. These observations provide insight into the plasticity of the flap domains, the nature of their motions and their critical role in binding substrates and inhibitors.

  7. Conformer-specific vibronic spectroscopy and vibronic coupling in a flexible bichromophore: Bis-(4-hydroxyphenyl)methane

    NASA Astrophysics Data System (ADS)

    Rodrigo, Chirantha P.; Müller, Christian W.; Pillsbury, Nathan R.; James, William H.; Plusquellic, David F.; Zwier, Timothy S.

    2011-04-01

    The vibronic spectroscopy of jet-cooled bis-(4-hydroxyphenyl)methane has been explored using fluorescence excitation, dispersed fluorescence (DFL), UV-UV hole-burning, UV depletion, and fluorescence-dip infrared spectroscopies. Calculations predict the presence of three nearly isoenergetic conformers that differ in the orientations of the two OH groups in the para positions on the two aromatic rings (labeled uu, dd, and ud). In practice, two conformers (labeled A and B) are observed, with S0-S1 origins at 35 184 and 35 209 cm-1, respectively. The two conformers have nearly identical vibronic spectra and hydride stretch infrared spectra. The low-frequency vibronic structure is assigned to bands involving the phenyl torsions (T and bar T), ring-flapping (R and bar R), and butterfly (β) modes. Symmetry arguments lead to a tentative assignment of the two conformers as the C2 symmetric uu and dd conformers. The S0-S2 origins are assigned to bands located 132 cm-1 above the S0-S1 origins of both conformers. DFL spectra from the S2 origin of the two conformers display extensive evidence for vibronic coupling between the two close-lying electronic states. Near-resonant coupling from the S2 origin occurs dominantly to S1 bar R^1 and S1 bar R^1 β ^1 levels, which are located -15 and +31 cm-1 from it. Unusual vibronic activity in the ring-breathing (ν1) and ring-deformation (ν6a) modes is also attributed to vibronic coupling involving these Franck-Condon active modes. A multimode vibronic coupling model is developed based on earlier theoretical descriptions of molecular dimers [Fulton and Gouterman, J. Chem. Phys. 35, 1059 (1961)] and applied here to flexible bichromophores. The model is able to account for the ring-mode activity under conditions in which the S2 origin is strongly mixed (60%/40%) with S1 overline {6a} ^1 and bar 1^1 levels. The direct extension of this model to the T /bar T and R /bar R inter-ring mode pairs is only partially successful and required some

  8. Conformational Flexibility and pH Effects on Anisotropic Growth of Sheet-Like Assembly of Amphiphilic Peptides.

    PubMed

    Huang, Hongzhou; Ganguly, Debabani; Chen, Jianhan; Sun, Xiuzhi S

    2015-06-01

    Peptide-based biomaterials have many potential applications in tissue engineering, drug delivery, surface engineering, and other areas. In this study, we exploited a series of amphiphilic diblock model peptides (L5K10, L5GSIIK10, and L5P(D)PK10) to understand how the supramolecular assembly morphology may be modulated by the physical properties of the peptide monomer and experimental conditions. A combination of experimentation and simulation revealed that although all three peptides lack stable structures as monomers, their levels of conformational heterogeneity differ significantly. Importantly, such differences appear to be correlated with the peptides' ability to form sheet-like assemblies. In particular, substantial conformational heterogeneity appears to be required for anisotropic growth of sheet-like materials, likely by reducing the peptide assembly kinetics. To test this hypothesis, we increased the pH to neutralize the lysine residues and promote peptide aggregation, and the resulting faster assembly rate hindered the growth of the sheet morphology as predicted. In addition, we designed and investigated the assembly morphologies of a series of diblock peptides with various lengths of polyglycine inserts, L5GxK10, x = 1, 2, 3, 4. The results further supported the importance of peptide conformational flexibility and pH in modulation of the peptide supramolecular assembly morphology.

  9. Ultra-flexible multiband terahertz metamaterial absorber for conformal geometry applications.

    PubMed

    Yahiaoui, Riad; Guillet, Jean Paul; de Miollis, Frédérick; Mounaix, Patrick

    2013-12-01

    Standard optical lithography relying on clean room and microelectronic facilities is used to fabricate a thin-flexible metamaterial absorber, designed to operate at submillimeter wavelengths over the 0.1-1 THz frequency band. Large terahertz absorption has been demonstrated numerically and through experimental measurements with a maximum level of about 80%. We put emphasis in this present work on the use of single-sized "meta-cells" to achieve multiple absorption peaks. Furthermore, the use of a thin-flexible dielectric spacer makes it promising for stealth technology applications in order to disguise objects and make them less visible to radar and other detection methods. PMID:24281490

  10. Anthrax Edema Factor: An Ion-Adaptive Mechanism of Catalysis with Increased Transition-State Conformational Flexibility.

    PubMed

    Jara, Gabriel E; Martínez, Leandro

    2016-07-14

    Edema Factor (EF) is one of three major toxins of anthrax. EF is an adenylyl cyclase that disrupts cell signaling by accelerating the conversion of ATP into cyclic-AMP. EF has a much higher catalytic rate than that of mammalian adenylyl cyclases (mACs). Crystal structures were obtained for mACs and EF, but the molecular basis for different catalytic activities remained poorly understood. In particular, the arrangement of the active site in EF is unclear in what concerns the number of ions present and the conformation of the substrate. Here, we use quantum mechanics-molecular mechanics simulations to estimate the free-energy profiles for the reaction catalyzed by EF and a mAC. We found that EF catalysis is possible, and faster than that of mACs, in both one and two Mg(2+)-ion-binding modes, providing adaptive plasticity to host-cell environments. In both enzymes, the reaction mechanisms are highly associative. However, mechanistic differences exist. In the mAC, the nucleophile oxygen (ATP-O3') is consistently coordinated to one of the Mg(2+) ions, increasing its acidity. In EF, on the other hand, this coordination is eventual and not essential for the reaction to proceed. The persistent coordination of O3' to the ion is favored in mACs by a greater ion partial charge. In EF, the reduced acidity of the O3' oxygen is compensated by the presence of the His351 residue for proton abstraction. As proton transfer in EF does not require persistent attachment of the substrate to an ion, the substrate (ATP) and transition state display greater conformational flexibilities. These greater flexibilities allow the sampling of lower-energy conformations and might represent an entropic advantage for catalytic efficiency. PMID:27260163

  11. Crystal structure and conformational flexibility of the unligated FK506-binding protein FKBP12.6

    SciTech Connect

    Chen, Hui; Mustafi, Sourajit M.; LeMaster, David M.; Li, Zhong; Héroux, Annie; Li, Hongmin; Hernández, Griselda

    2014-03-01

    Two crystal forms of unligated FKBP12.6 exhibit multiple conformations in the active site and in the 80s loop, the primary site for known protein-recognition interactions. The previously unreported NMR backbone assignment of FKBP12.6 revealed extensive doubling of amide resonances, which reflects a slow conformational transition centered in the 80s loop. The primary known physiological function of FKBP12.6 involves its role in regulating the RyR2 isoform of ryanodine receptor Ca{sup 2+} channels in cardiac muscle, pancreatic β islets and the central nervous system. With only a single previously reported X-ray structure of FKBP12.6, bound to the immunosuppressant rapamycin, structural inferences for this protein have been drawn from the more extensive studies of the homologous FKBP12. X-ray structures at 1.70 and 1.90 Å resolution from P2{sub 1} and P3{sub 1}21 crystal forms are reported for an unligated cysteine-free variant of FKBP12.6 which exhibit a notable diversity of conformations. In one monomer from the P3{sub 1}21 crystal form, the aromatic ring of Phe59 at the base of the active site is rotated perpendicular to its typical orientation, generating a steric conflict for the immunosuppressant-binding mode. The peptide unit linking Gly89 and Val90 at the tip of the protein-recognition ‘80s loop’ is flipped in the P2{sub 1} crystal form. Unlike the >30 reported FKBP12 structures, the backbone conformation of this loop closely follows that of the first FKBP domain of FKBP51. The NMR resonances for 21 backbone amides of FKBP12.6 are doubled, corresponding to a slow conformational transition centered near the tip of the 80s loop, as recently reported for 31 amides of FKBP12. The comparative absence of doubling for residues along the opposite face of the active-site pocket in FKBP12.6 may in part reflect attenuated structural coupling owing to increased conformational plasticity around the Phe59 ring.

  12. Triaspartate: a model system for conformationally flexible DDD motifs in proteins.

    PubMed

    Duitch, Laura; Toal, Siobhan; Measey, Thomas J; Schweitzer-Stenner, Reinhard

    2012-05-01

    Understanding the interactions that govern turn formation in the unfolded state of proteins is necessary for a complete picture of the role that these turns play in both normal protein folding and functionally relevant yet disordered linear motifs. It is still unclear, however, whether short peptides can adopt stable turn structures in aqueous environments in the absence of any nonlocal interactions. To explore the effect that nearest-neighbor interactions and the local peptide environment have on the turn-forming capability of individual amino acid residues in short peptides, we combined vibrational (IR, Raman, and VCD), UV-CD, and (1)H NMR spectroscopies in order to probe the conformational ensemble of the central aspartic acid residue of the triaspartate peptide (DDD). The study was motivated by the recently discovered turn propensities of aspartic acid in GDG (Hagarman; et al. Chem.-Eur. J. 2011, 17, 6789). We investigated the DDD peptide under both acidic and neutral conditions in order to elucidate the effect that side-chain protonation has on the conformational propensity of the central aspartic acid residue. Amide I' profiles were analyzed in terms of two-dimensional Gaussian distributions representing conformational subdistributions in Ramachandran space. Interestingly, our results show that while the protonated form of the DDD peptide samples various turn-like conformations similar to GDG, deprotonation of the peptide eliminates this propensity for turns, causing the fully ionized peptide to exclusively sample pPII and β-strand-like structures. To further explore the factors stabilizing these more extended conformations in fully ionized DDD, we analyzed the temperature dependence of both the UV-CD spectrum and the (3)J(H(N),H(α)) coupling constants of the two amide protons (N- and C-terminal) in terms of a simple two-state (pPII-β) thermodynamic model. Thus, we were able to obtain the enthalpic and entropic differences between the pPII and

  13. Structure of inorganic pyrophosphatase from Staphylococcus aureus reveals conformational flexibility of the active site.

    PubMed

    Gajadeera, Chathurada S; Zhang, Xinyi; Wei, Yinan; Tsodikov, Oleg V

    2015-02-01

    Cytoplasmic inorganic pyrophosphatase (PPiase) is an enzyme essential for survival of organisms, from bacteria to human. PPiases are divided into two structurally distinct families: family I PPiases are Mg(2+)-dependent and present in most archaea, eukaryotes and prokaryotes, whereas the relatively less understood family II PPiases are Mn(2+)-dependent and present only in some archaea, bacteria and primitive eukaryotes. Staphylococcus aureus (SA), a dangerous pathogen and a frequent cause of hospital infections, contains a family II PPiase (PpaC), which is an attractive potential target for development of novel antibacterial agents. We determined a crystal structure of SA PpaC in complex with catalytic Mn(2+) at 2.1Å resolution. The active site contains two catalytic Mn(2+) binding sites, each half-occupied, reconciling the previously observed 1:1 Mn(2+):enzyme stoichiometry with the presence of two divalent metal ion sites in the apo-enzyme. Unexpectedly, despite the absence of the substrate or products in the active site, the two domains of SA PpaC form a closed active site, a conformation observed in structures of other family II PPiases only in complex with substrate or product mimics. A region spanning residues 295-298, which contains a conserved substrate binding RKK motif, is flipped out of the active site, an unprecedented conformation for a PPiase. Because the mutant of Arg295 to an alanine is devoid of activity, this loop likely undergoes an induced-fit conformational change upon substrate binding and product dissociation. This closed conformation of SA PPiase may serve as an attractive target for rational design of inhibitors of this enzyme. PMID:25576794

  14. Conformational transitions of flexible hydrophobic polyelectrolytes in solutions of monovalent and multivalent salts and their mixtures.

    PubMed

    Trotsenko, Oleksandr; Roiter, Yuri; Minko, Sergiy

    2012-04-10

    Conformations of cationic polyelectrolytes (PEs), a weak poly(2-vinylpyridine) (P2VP) and a strong poly(N-methyl-2-vinylpyridinium iodide) (qP2VP), adsorbed on mica from saline solutions in the presence of counterions of different valences are studied using in situ atomic force microscopy (AFM). Quantitative characteristics of chain conformations are analyzed using AFM images of the adsorbed molecules. The results of the statistical analysis of the chain contour reveal collapse of the PE coils when ionic strength is in a range from tens to hundreds of millimoles per kilogram and re-expansion of the coils with a further increase of ionic strength up to a region of the saturated saline solutions. The competition between monovalent and multivalent counterions simultaneously present in solutions strongly affects conformations of PE chains even at a very small fraction of multivalent counterions. Shrinkage of PE coils is steeper for multivalent counterions than for monovalent counterions. However, the re-expansion is only incremental in the presence of multivalent counterions. Extended adsorbed coils at low salt concentrations and at very high concentrations of monovalent salt exhibit conformation corresponding to a 2D coil with 0.95 fraction of bound segments (segments in "trains") in the regime of diluted surface concentration of the PE. Shrunken coils in the intermediate range of ionic strength resemble 3D-globules with 0.8 fraction of trains. The incrementally re-expanded PE coils at a high ionic strength remain unchanged at higher multivalent salt concentrations up to the solubility limit of the salt. The formation of a strong PE complex with multivalent counterions at high ionic strength is not well understood yet. A speculative explanation of the observed experimental result is based on possible stabilization of the complex due to hydrophobic interactions of the backbone.

  15. Solid-State Conformational Flexibility at Work: Zipping and Unzipping within a Cyclic Peptoid Single Crystal.

    PubMed

    Meli, Alessandra; Macedi, Eleonora; De Riccardis, Francesco; Smith, Vincent J; Barbour, Leonard J; Izzo, Irene; Tedesco, Consiglia

    2016-04-01

    A peptidomimetic compound undergoes a reversible single-crystal-to-single-crystal transformation upon guest release/uptake with the transformation involving a drastic conformational change. The extensive and reversible alteration in the solid state is connected to the formation of an unprecedented "CH-π zipper" which can reversibly open and close (through the formation of CH-π interactions), thus allowing for guest sensing.

  16. Conformational diversity of flexible ligand in metal-organic frameworks controlled by size-matching mixed ligands

    NASA Astrophysics Data System (ADS)

    Hua, Xiu-Ni; Qin, Lan; Yan, Xiao-Zhi; Yu, Lei; Xie, Yi-Xin; Han, Lei

    2015-12-01

    Hydrothermal reactions of N-auxiliary flexible exo-bidentate ligand 1,3-bis(4-pyridyl)propane (bpp) and carboxylates ligands naphthalene-2,6-dicarboxylic acid (2,6-H2ndc) or 4,4‧-(hydroxymethylene)dibenzoic acid (H2hmdb), in the presence of cadmium(II) salts have given rise to two novel metal-organic frameworks based on flexible ligands (FL-MOFs), namely, [Cd2(2,6-ndc)2(bpp)(DMF)]·2DMF (1) and [Cd3(hmdb)3(bpp)]·2DMF·2EtOH (2) (DMF=N,N-Dimethylformamide). Single-crystal X-ray diffraction analyses revealed that compound 1 exhibits a three-dimensional self-penetrating 6-connected framework based on dinuclear cluster second building unit. Compound 2 displays an infinite three-dimensional 'Lucky Clover' shape (2,10)-connected network based on the trinuclear cluster and V-shaped organic linkers. The flexible bpp ligand displays different conformations in 1 and 2, which are successfully controlled by size-matching mixed ligands during the self-assembly process.

  17. Universal aspects of conformations and transverse fluctuations of a two-dimensional semi-flexible chain

    NASA Astrophysics Data System (ADS)

    Hsu, Hsiao-Ping; Huang, Aiqun; Bhattacharya, Aniket; Binder, Kurt

    2015-03-01

    In this talk we compare the results obtained from Monte Carlo (MC) and Brownian dynamics (BD) simulation for the universal properties of a semi-flexible chain. Specifically we compare MC results obtained using pruned-enriched Rosenbluth method (PERM) with those obtained from BD simulation. We find that the scaled plot of root-mean-square (RMS) end-to-end distance / 2 Llp and RMS transverse transverse fluctuations √{ } /lp as a function of L /lp (where L and lp are the contour length, and the persistence length respectively) are universal and independent of the definition of the persistence length used in MC and BD schemes. We further investigate to what extent these results agree for a semi-flexible polymer confined in a quasi one dimensional channel.

  18. Conformational Statistics of Semi-Flexible Macromolecular Chains with Internal Joints

    PubMed Central

    Zhou, Yu

    2010-01-01

    Fluctuations in the bending angles at internal irregularities of DNA and RNA (such as symmetric loops, bulges, and nicks/gaps) have been observed from various experiments. However, little effort has been made to computationally predict and explain the statistical behavior of semi-flexible chains with internal defects. In this paper, we describe the general structure of these macromolecular chains as inextensible elastic chains with one or more internal joints which have limited ranges of rotation, and propose a method to compute the probability density functions of the end-to-end pose of these macromolecular chains. Our method takes advantage of the operational properties of the non-commutative Fourier transform for the group of rigid-body motions in three-dimensional space, SE(3). Two representative types of joints, the hinge for planar rotation and the ball joint for spatial rotation, are discussed in detail. The proposed method applies to various stiffness models of semi-flexible chain-like macromolecules. Examples are calculated using the Kratky-Porod model with specified stiffness, angular fluctuation, and joint locations. Entropic effects associated with internal angular fluctuations of semi-flexible macromolecular chains with internal joints can be computed using this formulation. Our method also provides a potential tool to detect the existence of internal irregularities. PMID:21243113

  19. Unprecedented conformational flexibility revealed in the ligand-binding domains of the Bovicola ovis ecdysone receptor (EcR) and ultraspiracle (USP) subunits.

    PubMed

    Ren, Bin; Peat, Thomas S; Streltsov, Victor A; Pollard, Matthew; Fernley, Ross; Grusovin, Julian; Seabrook, Shane; Pilling, Pat; Phan, Tram; Lu, Louis; Lovrecz, George O; Graham, Lloyd D; Hill, Ronald J

    2014-07-01

    The heterodimeric ligand-binding region of the Bovicola ovis ecdysone receptor has been crystallized either in the presence of an ecdysteroid or a synthetic methylene lactam insecticide. Two X-ray crystallographic structures, determined at 2.7 Å resolution, show that the ligand-binding domains of both subunits of this receptor, like those of other nuclear receptors, can display significant conformational flexibility. Thermal melt experiments show that while ponasterone A stabilizes the higher order structure of the heterodimer in solution, the methylene lactam destabilizes it. The conformations of the EcR and USP subunits observed in the structure crystallized in the presence of the methylene lactam have not been seen previously in any ecdysone receptor structure and represent a new level of conformational flexibility for these important receptors. Interestingly, the new USP conformation presents an open, unoccupied ligand-binding pocket.

  20. Conformational Flexibility and Peptide Interaction of the Translocation ATPase SecA

    SciTech Connect

    Zimmer, Jochen; Rapoport, Tom A.; Harvard-Med

    2010-09-21

    The SecA ATPase forms a functional complex with the protein-conducting SecY channel to translocate polypeptides across the bacterial cell membrane. SecA recognizes the translocation substrate and catalyzes its unidirectional movement through the SecY channel. The recent crystal structure of the Thermotoga maritima SecA-SecYEG complex shows the ATPase in a conformation where the nucleotide-binding domains (NBDs) have closed around a bound ADP-BeFx complex and SecA's polypeptide-binding clamp is shut. Here, we present the crystal structure of T. maritima SecA in isolation, determined in its ADP-bound form at 3.1 {angstrom} resolution. SecA alone has a drastically different conformation in which the nucleotide-binding pocket between NBD1 and NBD2 is open and the preprotein cross-linking domain has rotated away from both NBDs, thereby opening the polypeptide-binding clamp. To investigate how this clamp binds polypeptide substrates, we also determined a structure of Bacillus subtilis SecA in complex with a peptide at 2.5 {angstrom} resolution. This structure shows that the peptide augments the highly conserved {beta}-sheet at the back of the clamp. Taken together, these structures suggest a mechanism by which ATP hydrolysis can lead to polypeptide translocation.

  1. Structure analysis and catalytic property of a microporous framework based on a flexible tripodal ligand with novel conformations

    NASA Astrophysics Data System (ADS)

    Shi, Xianju; Zhang, Xinhai; Li, Xiaoxia; Hou, Hongwei; Fan, Yaoting

    2011-06-01

    A microporous metal-organic framework {[Cu 3Cl 6(ttmb) 4]·6H 2O} n ( 1) (ttmb = 1,3,5-tris(1,2,4-triazol-1-ylmethyl)-benzene) with tetranodal (3,4)-connected topological type was prepared by the self-assembly reaction of the flexible tripodal ligand ttmb with CuCl 2·2H 2O. The ligand exhibits two infrequent coordination conformations in complex 1, and the framework has a large pore volume (remove the solvent molecules) of 1781.6 Å 3 (36.3% of the total). The test of 1 as the catalyst in the oxidative coupling reaction of 2,6-dimethylphenol indicates that it is catalytically active by showing high conversion of DMP under the optimized reaction condition.

  2. The Large Area Crop Inventory Experiment (LACIE)

    NASA Technical Reports Server (NTRS)

    Macdonald, R. B.

    1976-01-01

    A Large Area Crop Inventory Experiment (LACIE) was undertaken to prove out an economically important application of remote sensing from space. The experiment focused upon determination of wheat acreages in the U.S. Great Plains and upon the development and testing of yield models. The results and conclusions are presented.

  3. Large area space solar cell assemblies

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Nowlan, M. J.

    1982-01-01

    Development of a large area space solar cell assembly is presented. The assembly consists of an ion implanted silicon cell and glass cover. The important attributes of fabrication are (1) use of a back surface field which is compatible with a back surface reflector, and (2) integration of coverglass application and call fabrication.

  4. Body conformal antennas for superficial hyperthermia: the impact of bending contact flexible microstrip applicators on their electromagnetic behavior.

    PubMed

    Correia, Davi; Kok, H Petra; de Greef, Martijn; Bel, Arjan; van Wieringen, Niek; Crezee, Johannes

    2009-12-01

    Hyperthermia is a powerful radiosensitizer for treatment of superficial tumors. This requires body conformal antennas with a power distribution as homogeneous as possible over the skin area. The contact flexible microstrip applicators (CFMA) operating at 434 MHz exist in several sizes, including the large size 3H and 5H. This paper investigates the behavior of the electromagnetic fields for the 3H and 5H CFMA in both flat and curved configurations, and the impact on performance parameters like the penetration depth (PD) and the effective heating depth (EHD). The underlying theory behind the electromagnetic behavior in curved situations is presented as well as numerical simulations of both flat and curved configurations. The results are compared to measurements of the electromagnetic field distributions in a cylindrical patient model. Due to their large size multimode solutions may exist, and our results confirm their existence. These multimode solutions affect both the power distribution and PD/EHD, with a dependence on applicator curvature. Therefore, the performance parameters like PD and EHD need to be carefully assessed when bending large size CFMA applicators to conform to the patient body. This conclusion also holds for other types of large size surface current applicators. PMID:19695983

  5. Body conformal antennas for superficial hyperthermia: the impact of bending contact flexible microstrip applicators on their electromagnetic behavior.

    PubMed

    Correia, Davi; Kok, H Petra; de Greef, Martijn; Bel, Arjan; van Wieringen, Niek; Crezee, Johannes

    2009-12-01

    Hyperthermia is a powerful radiosensitizer for treatment of superficial tumors. This requires body conformal antennas with a power distribution as homogeneous as possible over the skin area. The contact flexible microstrip applicators (CFMA) operating at 434 MHz exist in several sizes, including the large size 3H and 5H. This paper investigates the behavior of the electromagnetic fields for the 3H and 5H CFMA in both flat and curved configurations, and the impact on performance parameters like the penetration depth (PD) and the effective heating depth (EHD). The underlying theory behind the electromagnetic behavior in curved situations is presented as well as numerical simulations of both flat and curved configurations. The results are compared to measurements of the electromagnetic field distributions in a cylindrical patient model. Due to their large size multimode solutions may exist, and our results confirm their existence. These multimode solutions affect both the power distribution and PD/EHD, with a dependence on applicator curvature. Therefore, the performance parameters like PD and EHD need to be carefully assessed when bending large size CFMA applicators to conform to the patient body. This conclusion also holds for other types of large size surface current applicators.

  6. Kalata B8, a novel antiviral circular protein, exhibits conformational flexibility in the cystine knot motif.

    PubMed

    Daly, Norelle L; Clark, Richard J; Plan, Manuel R; Craik, David J

    2006-02-01

    The cyclotides are a family of circular proteins with a range of biological activities and potential pharmaceutical and agricultural applications. The biosynthetic mechanism of cyclization is unknown and the discovery of novel sequences may assist in achieving this goal. In the present study, we have isolated a new cyclotide from Oldenlandia affinis, kalata B8, which appears to be a hybrid of the two major subfamilies (Möbius and bracelet) of currently known cyclotides. We have determined the three-dimensional structure of kalata B8 and observed broadening of resonances directly involved in the cystine knot motif, suggesting flexibility in this region despite it being the core structural element of the cyclotides. The cystine knot motif is widespread throughout Nature and inherently stable, making this apparent flexibility a surprising result. Furthermore, there appears to be isomerization of the peptide backbone at an Asp-Gly sequence in the region involved in the cyclization process. Interestingly, such isomerization has been previously characterized in related cyclic knottins from Momordica cochinchinensis that have no sequence similarity to kalata B8 apart from the six conserved cysteine residues and may result from a common mechanism of cyclization. Kalata B8 also provides insight into the structure-activity relationships of cyclotides as it displays anti-HIV activity but lacks haemolytic activity. The 'uncoupling' of these two activities has not previously been observed for the cyclotides and may be related to the unusual hydrophilic nature of the peptide. PMID:16207177

  7. Kalata B8, a novel antiviral circular protein, exhibits conformational flexibility in the cystine knot motif.

    PubMed

    Daly, Norelle L; Clark, Richard J; Plan, Manuel R; Craik, David J

    2006-02-01

    The cyclotides are a family of circular proteins with a range of biological activities and potential pharmaceutical and agricultural applications. The biosynthetic mechanism of cyclization is unknown and the discovery of novel sequences may assist in achieving this goal. In the present study, we have isolated a new cyclotide from Oldenlandia affinis, kalata B8, which appears to be a hybrid of the two major subfamilies (Möbius and bracelet) of currently known cyclotides. We have determined the three-dimensional structure of kalata B8 and observed broadening of resonances directly involved in the cystine knot motif, suggesting flexibility in this region despite it being the core structural element of the cyclotides. The cystine knot motif is widespread throughout Nature and inherently stable, making this apparent flexibility a surprising result. Furthermore, there appears to be isomerization of the peptide backbone at an Asp-Gly sequence in the region involved in the cyclization process. Interestingly, such isomerization has been previously characterized in related cyclic knottins from Momordica cochinchinensis that have no sequence similarity to kalata B8 apart from the six conserved cysteine residues and may result from a common mechanism of cyclization. Kalata B8 also provides insight into the structure-activity relationships of cyclotides as it displays anti-HIV activity but lacks haemolytic activity. The 'uncoupling' of these two activities has not previously been observed for the cyclotides and may be related to the unusual hydrophilic nature of the peptide.

  8. Protein Conformational Flexibility Enables the Formation of Dense Liquid Clusters: Tests Using Solution Shear.

    PubMed

    Byington, Michael C; Safari, Mohammad S; Conrad, Jacinta C; Vekilov, Peter G

    2016-07-01

    According to recently proposed two-step nucleation mechanisms, crystal nuclei form within preexisting dense liquid clusters. Clusters with radii about 100 nm, which capture from 10(-7) to 10(-3) of the total protein, have been observed with numerous proteins and shown to host crystal nucleation. Theories aiming to understand the mesoscopic size and small protein fraction held in the clusters have proposed that in solutions of single-chain proteins, the clusters consist of partially misfolded protein molecules. To test this conjecture, we perturb the protein conformation by shearing solutions of the protein lysozyme. We demonstrate that shear rates greater than a threshold applied for longer than 1 h reduce the volume of the cluster population. The likely mechanism of the observed response involves enhanced partial unfolding of lysozyme molecules, which exposes hydrophobic surfaces between the constituent domains to the aqueous solution. PMID:27267087

  9. Substituted naphthalenes: Stability, conformational flexibility and description of bonding based on ETS-NOCV method

    NASA Astrophysics Data System (ADS)

    Stanković, B.; Ostojić, B. D.; Gruden, M.; Popović, A.; Đorđević, D. S.

    2016-09-01

    For all dimethylnaphthalenes (DMNs) the transition from a planar ring conformation to a nonplanar one results in energy increase in the range 1.7-2.4 kcal/mol. There is a linear relationship between averaged rigidity constant and relative energy of DMNs. The relative stability of DMNs does not follow the aromatic stabilization based on NICS values. The ETS-NOCV analysis shows that more efficient bonding in the π-electron system is the origin of enhanced stability in laterally substituted (CH3, Cl and NO2) naphthalenes. The results for Caryl-CH3 system indicate more steric repulsion in going from 2,7-DMN to 1,8-DMN following the increase of relative energies.

  10. Stabilizing a flexible interdomain hinge region harboring the SMB binding site drives uPAR into its closed conformation.

    PubMed

    Zhao, Baoyu; Gandhi, Sonu; Yuan, Cai; Luo, Zhipu; Li, Rui; Gårdsvoll, Henrik; de Lorenzi, Valentina; Sidenius, Nicolai; Huang, Mingdong; Ploug, Michael

    2015-03-27

    The urokinase-type plasminogen activator receptor (uPAR) is a multidomain glycolipid-anchored membrane protein, which facilitates extracellular matrix remodeling by focalizing plasminogen activation to cell surfaces via its high-affinity interaction with uPA. The modular assembly of its three LU (Ly6/uPAR-like) domains is inherently flexible and binding of uPA drives uPAR into its closed conformation, which presents the higher-affinity state for vitronectin thus providing an allosteric regulatory mechanism. Using a new class of epitope-mapped anti-uPAR monoclonal antibodies (mAbs), we now demonstrate that the reciprocal stabilization is indeed also possible. By surface plasmon resonance studies, we show that these mAbs and vitronectin have overlapping binding sites on uPAR and that they share Arg91 as hotspot residue in their binding interfaces. The crystal structure solved for one of these uPAR·mAb complexes at 3.0Å clearly shows that this mAb preselects the closed uPAR conformation with an empty but correctly assembled large hydrophobic binding cavity for uPA. Accordingly, these mAbs inhibit the uPAR-dependent lamellipodia formation and migration on vitronectin-coated matrices irrespective of the conformational status of uPAR and its occupancy with uPA. This is the first study to the best of our knowledge, showing that the dynamic assembly of the three LU domains in uPARwt can be driven toward the closed form by an external ligand, which is not engaging the hydrophobic uPA binding cavity. As this binding interface is also exploited by the somatomedin B domain of vitronectin, therefore, this relationship should be taken into consideration when exploring uPAR-dependent cell adhesion and migration in vitronectin-rich environments. PMID:25659907

  11. Large-area nanoscale patterning: chemistry meets fabrication.

    PubMed

    Henzie, Joel; Barton, Jeremy E; Stender, Christopher L; Odom, Teri W

    2006-04-01

    This Account describes a new paradigm for large-area nanoscale patterning that combines bottom-up and top-down approaches, merging chemistry with fabrication. This hybrid strategy uses simple nanofabrication techniques to control the alignment, size, shape, and periodicity of nanopatterns and chemical methods to control their materials properties and crystallinity. These tools are highly flexible and can create surface-patterned nanostructures with unusual properties and free-standing nanostructures that are multifunctional and monodisperse. The unprecedented scientific and technological opportunities enabled by nanoscale patterning over wafer-sized areas are discussed.

  12. Probing the ATP-induced conformational flexibility of the PcrA helicase protein using molecular dynamics simulation.

    PubMed

    Mhashal, Anil R; Choudhury, Chandan Kumar; Roy, Sudip

    2016-03-01

    Helicases are enzymes that unwind double-stranded DNA (dsDNA) into its single-stranded components. It is important to understand the binding and unbinding of ATP from the active sites of helicases, as this knowledge can be used to elucidate the functionality of helicases during the unwinding of dsDNA. In this work, we investigated the unbinding of ATP and its effect on the active-site residues of the helicase PcrA using molecular dynamic simulations. To mimic the unbinding process of ATP from the active site of the helicase, we simulated the application of an external force that pulls ATP from the active site and computed the free-energy change during this process. We estimated an energy cost of ~85 kJ/mol for the transformation of the helicase from the ATP-bound state (1QHH) to the ATP-free state (1PJR). Unbinding led to conformational changes in the residues of the protein at the active site. Some of the residues at the ATP-binding site were significantly reoriented when the ATP was pulled. We observed a clear competition between reorientation of the residues and energy stabilization by hydrogen bonds between the ATP and active-site residues. We also checked the flexibility of the PcrA protein using a principal component analysis of domain motion. We found that the ATP-free state of the helicase is more flexible than the ATP-bound state.

  13. GLAST Large Area Telescope Multiwavelength Planning

    SciTech Connect

    Reimer, O.; Michelson, P.F.; Cameron, R.A.; Digel, S.W.; Thompson, D.J.; Wood, K.S.

    2007-01-03

    Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-band blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.

  14. GLAST Large Area Telescope Multiwavelength Planning

    NASA Technical Reports Server (NTRS)

    Reimer, O.; Michelson, P. F.; Cameron, R. A.; Digel, S. W.; Thompson, D. J.; Wood, K. S.

    2007-01-01

    Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.

  15. Development of large-area glass GEM

    NASA Astrophysics Data System (ADS)

    Mitsuya, Yuki; Fujiwara, Takeshi; Fushie, Takashi; Maekawa, Tatsuyuki; Takahashi, Hiroyuki

    2015-09-01

    We have developed a new gaseous radiation detector, referred to as the Glass GEM (G-GEM). The G-GEM is composed of a photosensitive etching glass (PEG3) substrate from HOYA Corporation, Japan. Since a large-area detector is required for imaging device applications, we newly developed a large-area G-GEM prototype with a sensitive area of 280×280 mm2. In this study, we investigated its basic characteristics and confirmed that it worked properly and had sufficient uniformity across the entire sensitive area. It had high gas gain of up to approximately 7700, along with good energy resolution of 26.2% (FWHM) for a 5.9-keV X-ray with a gas mixture of Ar (90%) and CH4 (10%). The gain variation across the sensitive area was almost within the range of ±10%.

  16. The Structural Basis for Peptidomimetic Inhibition of Eukaryotic Ribonucleotide Reductase: A Conformationally Flexible Pharmacophore

    SciTech Connect

    Xu, Hai; Fairman, James W.; Wijerathna, Sanath R.; Kreischer, Nathan R.; LaMacchia, John; Helmbrecht, Elizabeth; Cooperman, Barry S.; Dealwis, Chris

    2008-08-19

    Eukaryotic ribonucleotide reductase (RR) catalyzes nucleoside diphosphate conversion to deoxynucleoside diphosphate. Crucial for rapidly dividing cells, RR is a target for cancer therapy. RR activity requires formation of a complex between subunits R1 and R2 in which the R2 C-terminal peptide binds to R1. Here we report crystal structures of heterocomplexes containing mammalian R2 C-terminal heptapeptide, P7 (Ac-{sup 1}FTLDADF{sup 7}) and its peptidomimetic P6 ({sup 1}Fmoc(Me)PhgLDChaDF{sup 7}) bound to Saccharomyces cerevisiae R1 (ScR1). P7 and P6, both of which inhibit ScRR, each bind at two contiguous sites containing residues that are highly conserved among eukaryotes. Such binding is quite distinct from that reported for prokaryotes. The Fmoc group in P6 peptide makes several hydrophobic interactions that contribute to its enhanced potency in binding to ScR1. Combining all of our results, we observe three distinct conformations for peptide binding to ScR1. These structures provide pharmacophores for designing highly potent nonpeptide class I RR inhibitors.

  17. Cwp84, a Clostridium difficile cysteine protease, exhibits conformational flexibility in the absence of its propeptide

    SciTech Connect

    Bradshaw, William J.; Roberts, April K.; Shone, Clifford C.; Acharya, K. Ravi

    2015-02-19

    Two structures of Cwp84, a cysteine protease from the S-layer of C. difficile, are presented after propeptide cleavage. They reveal the movement of three loops, two in the active-site groove and one on the surface of the lectin-like domain, exposing a hydrophobic pocket. In recent decades, the global healthcare problems caused by Clostridium difficile have increased at an alarming rate. A greater understanding of this antibiotic-resistant bacterium, particularly with respect to how it interacts with the host, is required for the development of novel strategies for fighting C. difficile infections. The surface layer (S-layer) of C. difficile is likely to be of significant importance to host–pathogen interactions. The mature S-layer is formed by a proteinaceous array consisting of multiple copies of a high-molecular-weight and a low-molecular-weight S-layer protein. These components result from the cleavage of SlpA by Cwp84, a cysteine protease. The structure of a truncated Cwp84 active-site mutant has recently been reported and the key features have been identified, providing the first structural insights into the role of Cwp84 in the formation of the S-layer. Here, two structures of Cwp84 after propeptide cleavage are presented and the three conformational changes that are observed are discussed. These changes result in a reconfiguration of the active site and exposure of the hydrophobic pocket.

  18. Cwp84, a Clostridium difficile cysteine protease, exhibits conformational flexibility in the absence of its propeptide.

    PubMed

    Bradshaw, William J; Roberts, April K; Shone, Clifford C; Acharya, K Ravi

    2015-03-01

    In recent decades, the global healthcare problems caused by Clostridium difficile have increased at an alarming rate. A greater understanding of this antibiotic-resistant bacterium, particularly with respect to how it interacts with the host, is required for the development of novel strategies for fighting C. difficile infections. The surface layer (S-layer) of C. difficile is likely to be of significant importance to host-pathogen interactions. The mature S-layer is formed by a proteinaceous array consisting of multiple copies of a high-molecular-weight and a low-molecular-weight S-layer protein. These components result from the cleavage of SlpA by Cwp84, a cysteine protease. The structure of a truncated Cwp84 active-site mutant has recently been reported and the key features have been identified, providing the first structural insights into the role of Cwp84 in the formation of the S-layer. Here, two structures of Cwp84 after propeptide cleavage are presented and the three conformational changes that are observed are discussed. These changes result in a reconfiguration of the active site and exposure of the hydrophobic pocket. PMID:25760704

  19. Large-area lanthanum hexaboride electron emitter

    NASA Astrophysics Data System (ADS)

    Goebel, D. M.; Hirooka, Y.; Sketchley, T. A.

    1985-09-01

    The characteristics of lanthanum-boron thermionic electron emitters are discussed, and a large-area, continuously operating cathode assembly and heater are described. Impurity production and structural problems involving the support of the LaB6 have been eliminated in the presented configuration. The performance of the cathode in a plasma discharge, where surface modification occurs by ion sputtering, is presented. Problem areas which affect lifetime and emission current capability are discussed.

  20. Large-area thin-film modules

    NASA Technical Reports Server (NTRS)

    Tyan, Y. S.; Perez-Albuerne, E. A.

    1985-01-01

    The low cost potential of thin film solar cells can only be fully realized if large area modules can be made economically with good production yields. This paper deals with two of the critical challenges. A scheme is presented which allows the simple, economical realization of the long recognized, preferred module structure of monolithic integration. Another scheme reduces the impact of shorting defects and, as a result, increases the production yields. Analytical results demonstrating the utilization and advantages of such schemes are discussed.

  1. Conformation of a flexible polymer in explicit solvent: Accurate solvation potentials for Lennard-Jones chains.

    PubMed

    Taylor, Mark P; Ye, Yuting; Adhikari, Shishir R

    2015-11-28

    The conformation of a polymer chain in solution is coupled to the local structure of the surrounding solvent and can undergo large changes in response to variations in solvent density and temperature. The many-body effects of solvent on the structure of an n-mer polymer chain can be formally mapped to an exact n-body solvation potential. Here, we use a pair decomposition of this n-body potential to construct a set of two-body potentials for a Lennard-Jones (LJ) polymer chain in explicit LJ solvent. The solvation potentials are built from numerically exact results for 5-mer chains in solvent combined with an approximate asymptotic expression for the solvation potential between sites that are distant along the chain backbone. These potentials map the many-body chain-in-solvent problem to a few-body single-chain problem and can be used to study a chain of arbitrary length, thereby dramatically reducing the computational complexity of the polymer chain-in-solvent problem. We have constructed solvation potentials at a large number of state points across the LJ solvent phase diagram including the vapor, liquid, and super-critical regions. We use these solvation potentials in single-chain Monte Carlo (MC) simulations with n ≤ 800 to determine the size, intramolecular structure, and scaling behavior of chains in solvent. To assess our results, we have carried out full chain-in-solvent MC simulations (with n ≤ 100) and find that our solvation potential approach is quantitatively accurate for a wide range of solvent conditions for these chain lengths. PMID:26627969

  2. Large Area X-Ray Spectroscopy Mission

    NASA Technical Reports Server (NTRS)

    Tananbaum, H.

    1997-01-01

    The Large Area X-ray Spectroscopy (LAXS) mission concept study continues to evolve strongly following the merging of the LAXS mission with the Next Generation X-ray Observatory (NGXO, PI: Nick White) into the re-named High Throughput X-ray Spectroscopy (HTXS) Mission. HTXS retains key elements of the LAXS proposal, including the use of multiple satellites for risk-reduction and cost savings. A key achievement of the program has been the recommendation by the Structure and Evolution of the Universe (SEUS) (April 1997) for a new start for the HTXS mission in the 2000-2004 timeframe.

  3. High Efficiency Large Area Polysilicon Solar Cells

    NASA Technical Reports Server (NTRS)

    Johnson, S. M.; Winter, C.

    1985-01-01

    Large area (100 sq cm) polysilicon solar cells having efficiencies of up to 14.1% (100 mW/sq cm, 25 C) were fabricated and a detailed analysis was performed to identify the efficiency loss mechanisms. The 1-5 characteristics of the best cell were dominated by recombination in the quasi-neutral base due to the combination of minority carrier diffusion length and base resistivity. An analysis of the microstructural defects present in the material and their effect on the electrical properties is presented.

  4. Large area cold plasma applicator for decontamination

    NASA Astrophysics Data System (ADS)

    Konesky, G. A.

    2008-04-01

    Cold plasma applicators have been used in the Medical community for several years for uses ranging from hemostasis ("stop bleeding") to tumor removal. An added benefit of this technology is enhanced wound healing by the destruction of infectious microbial agents without damaging healthy tissue. The beam is typically one millimeter to less than a centimeter in diameter. This technology has been adapted and expanded to large area applicators of potentially a square meter or more. Decontamination applications include both biological and chemical agents, and assisting in the removal of radiological agents, with minimal or no damage to the contaminated substrate material. Linear and planar multiemitter array plasma applicator design and operation is discussed.

  5. Timing Characteristics of Large Area Picosecond Photodetectors

    SciTech Connect

    Adams, Bernhard W.; Elagin, Andrey L.; Frisch, H.; Obaid, Razib; Oberla, E; Vostrikov, Alexander; Wagner, Robert G.; Wang, Jingbo; Wetstein, Matthew J.; Northrop, R

    2015-09-21

    The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  6. Large area position sensitive β-detector

    NASA Astrophysics Data System (ADS)

    Vaintraub, S.; Hass, M.; Edri, H.; Morali, N.; Segal, T.

    2015-03-01

    A new conceptual design of a large area electron detector, which is position and energy sensitive, was developed. This detector is designed for beta decay energies up to 4 MeV, but in principle can be re-designed for higher energies. The detector incorporates one large plastic scintillator and, in general, a limited number of photomultipliers (7 presently). The current setup was designed and constructed after an extensive Geant4 simulation study. By comparison of a single hit light distribution between the various photomultipliers to a pre-measured accurate position-response map, the anticipated position resolution is around 5 mm. The first benchmark experiments have been conducted in order to calibrate and confirm the position resolution of the detector. The new method, results of the first test experiments and comparison to simulations are presented.

  7. The CLAS12 large area RICH detector

    SciTech Connect

    M. Contalbrigo, E. Cisbani, P. Rossi

    2011-05-01

    A large area RICH detector is being designed for the CLAS12 spectrometer as part of the 12 GeV upgrade program of the Jefferson Lab Experimental Hall-B. This detector is intended to provide excellent hadron identification from 3 GeV/c up to momenta exceeding 8 GeV/c and to be able to work at the very high design luminosity-up to 1035 cm2 s-1. Detailed feasibility studies are presented for two types of radiators, aerogel and liquid C6F14 freon, in conjunction with a highly segmented light detector in the visible wavelength range. The basic parameters of the RICH are outlined and the resulting performances, as defined by preliminary simulation studies, are reported.

  8. The CLAS12 large area RICH detector

    NASA Astrophysics Data System (ADS)

    Contalbrigo, M.; Cisbani, E.; Rossi, P.

    2011-05-01

    A large area RICH detector is being designed for the CLAS12 spectrometer as part of the 12 GeV upgrade program of the Jefferson Lab Experimental Hall-B. This detector is intended to provide excellent hadron identification from 3 GeV/ c up to momenta exceeding 8 GeV/ c and to be able to work at the very high design luminosity-up to 10 35 cm 2 s -1. Detailed feasibility studies are presented for two types of radiators, aerogel and liquid C 6F 14 freon, in conjunction with a highly segmented light detector in the visible wavelength range. The basic parameters of the RICH are outlined and the resulting performances, as defined by preliminary simulation studies, are reported.

  9. Timing characteristics of Large Area Picosecond Photodetectors

    NASA Astrophysics Data System (ADS)

    Adams, B. W.; Elagin, A.; Frisch, H. J.; Obaid, R.; Oberla, E.; Vostrikov, A.; Wagner, R. G.; Wang, J.; Wetstein, M.

    2015-09-01

    The LAPPD Collaboration was formed to develop ultrafast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub-picosecond laser. We observe single-photoelectron time resolutions of a 20 cm × 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 μm, and median gains higher than 107. The RMS measured at one particular point on an LAPPD detector is 58 ps, with ± 1σ of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  10. The Large Area Pulsed Solar Simulator (LAPSS)

    NASA Technical Reports Server (NTRS)

    Mueller, R. L.

    1993-01-01

    A Large Area Pulsed Solar Simulator (LAPSS) has been installed at JPL. It is primarily intended to be used to illuminate and measure the electrical performance of photovoltaic devices. The simulator, originally manufactured by Spectrolab, Sylmar, California, occupies an area measuring about 3 meters wide by 12 meters long. The data acquisition and data processing subsystems have been modernized. Tests on the LAPSS performance resulted in better than +/- 2 percent uniformity of irradiance at the test plane and better than +/- 0.3 percent measurement repeatability after warm-up. Glass absorption filters are used to reduce the level of ultraviolet light emitted from the xenon flash lamps. This provides a close match to standard airmass zero and airmass 1.5 spectral irradiance distributions. The 2 millisecond light pulse prevents heating of the device under test, resulting in more reliable temperature measurements. Overall, excellent electrical performance measurements have been made of many different types and sizes of photovoltaic devices.

  11. Large area radiation detectors based on II VI thin films

    NASA Astrophysics Data System (ADS)

    Quevedo-Lopez, Manuel

    2015-03-01

    The development of low temperature device technologies that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible, low metal content, sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, neutron/gamma-ray/x-ray detectors, etc. In this talk, our efforts to develop novel CMOS integration schemes, circuits, memory, sensors as well as novel contacts, dielectrics and semiconductors for flexible electronics are presented. In particular, in this presentation we discuss fundamental materials properties including crystalline structure, interfacial reactions, doping, etc. defining performance and reliability of II-VI-based radiation sensors. We investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. Besides II-VI materials, we also evaluated several diode materials, Si, CdTe,GaAs, C (diamond), and ZnO, and two neutron converter materials,10B and 6LiF. We determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  12. Fermi Large Area Telescope Second Source Catalog

    NASA Astrophysics Data System (ADS)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Cañadas, B.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; DeCesar, M. E.; DeKlotz, M.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Enoto, T.; Escande, L.; Fabiani, D.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, R. P.; Johnson, T. E.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Pinchera, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Roth, M.; Rousseau, R.; Ryde, F.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Shaw, M. S.; Shrader, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Van Etten, A.; Van Klaveren, B.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

    2012-04-01

    We present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes. We dedicate this paper to the memory of our colleague Patrick Nolan, who died on 2011 November 6. His career spanned much of the history of high-energy astronomy from space and his work on the Large Area Telescope (LAT) began nearly 20 years ago when it was just a concept. Pat was a central member in the operation of the LAT collaboration and he is greatly missed.

  13. Electrohydrodynamically driven large-area liquid ion sources

    DOEpatents

    Pregenzer, Arian L.

    1988-01-01

    A large-area liquid ion source comprises means for generating, over a large area of the surface of a liquid, an electric field of a strength sufficient to induce emission of ions from a large area of said liquid. Large areas in this context are those distinct from emitting areas in unidimensional emitters.

  14. Conformation of a flexible chain in explicit solvent: exact solvation potentials for short Lennard-Jones chains.

    PubMed

    Taylor, Mark P; Adhikari, Shishir R

    2011-07-28

    The average conformation of a flexible chain molecule in solution is coupled to the local solvent structure. In a dense solvent, local chain structure often mirrors the pure solvent structure, whereas, in a dilute solvent, the chain can strongly perturb the solvent structure which, in turn, can lead to either chain expansion or compression. Here we use Monte Carlo (MC) simulation to study such solvent effects for a short Lennard-Lones (LJ) chain in monomeric LJ solvent. For an n-site chain molecule in solution these many-body solvent effects can be formally mapped to an n-body solvation potential. We have previously shown that for hard-sphere and square-well chain-in-solvent systems this n-body potential can be decomposed into a set of two-body potentials. Here, we show that this decomposition is also valid for the LJ system. Starting from high precision MC results for the n = 5 LJ chain-in-solvent system, we use a Boltzmann inversion technique to compute numerically exact sets of two-body solvation potentials which map the many-body chain-in-solvent problem to a few-body single-chain problem. We have carried out this mapping across the full solvent phase diagram including the dilute vapor, dense liquid, and supercritical regions and find that these sets of solvation potentials are able to encode the complete range of solvent effects found in the LJ chain-in-solvent system. We also show that these two-site solvation potentials can be used to obtain accurate multi-site intramolecular distribution functions and we discuss the application of these exact short chain potentials to the study of longer chains in solvent. PMID:21806157

  15. Antibody Binding Studies Reveal Conformational Flexibility of the Bacillus cereus Non-Hemolytic Enterotoxin (Nhe) A-Component

    PubMed Central

    Märtlbauer, E.

    2016-01-01

    The non-hemolytic enterotoxin complex (Nhe) is supposed to be the main virulence factor of B. cereus causing a diarrheal outcome of food poisoning. This tripartite toxin consists of the single components NheA, -B and -C all of them being necessary for maximum toxicity. In the past, research activities aiming to elucidate the mode-of-action of Nhe were mostly focused on the B- and C-component. In this study the generation of novel monoclonal antibodies (mAb) and their thorough characterization enabled the determination of key features for NheA. By the means of immunoaffinity chromatography it could be shown that NheA does not interact with -B and -C in solution. Additionally, the establishment of a highly sensitive sandwich-EIA now enables the detection of NheA in B. cereus supernatants down to 20 pg ml-1.Peptide-based epitope mapping in combination with partially deleted recombinant NheA fragments allowed the allocation of the binding regions for the three mAbs under study. Furthermore, by different EIA set-ups the conformational flexibility of NheA could be shown. For two of the antibodies under study different mechanisms of NheA neutralization were proven. Due to prevention of complete pore formation by one of the antibodies, NheA could be detected in an intermediate stage of the tripartite complex on the cell surface. Taken together, the results obtained in the present study allow a refinement of the mode-of-action for the Nhe toxin-complex. PMID:27768742

  16. Metal-free and transition-metal tetraferrocenylporphyrins part 1: synthesis, characterization, electronic structure, and conformational flexibility of neutral compounds.

    PubMed

    Nemykin, Victor N; Galloni, Pierluca; Floris, Barbara; Barrett, Christopher D; Hadt, Ryan G; Subbotin, Roman I; Marrani, Andrea G; Zanoni, Robertino; Loim, Nikolay M

    2008-08-28

    H(2)TFcP [TFcP = 5,10,15,20-tetraferrocenyl porphyrin(2-)] was prepared by a direct tetramerization reaction between pyrrole and ferrocene carbaldehyde in the presence of a BF(3) catalyst, while the series of MTFcP (M = Zn, Ni, Co and Cu) were prepared by a metallation reaction between H(2)TFcP and respective metal acetates. All compounds were characterized by UV-vis and MCD spectroscopy, APCI MS and MS/MS methods, high-resolution ESI MS and XPS spectroscopy. Diamagnetic compounds were additionally characterized using (1)H and (13)C NMR methods, while the presence of low-spin iron(ii) centers in the neutral compounds was confirmed by Mössbauer spectroscopy and by analysis of the XPS Fe 2p peaks, revealing equivalent Fe sites. XPS additionally showed the influence on Fe 2p binding energies exerted by the distinct central metal ions. The conformational flexibility of ferrocene substituents in H(2)TFcP and MTFcP, was confirmed using variable-temperature NMR and computational methods. Density functional theory predicts that alpha,beta,alpha,beta atropisomers with ruffled porphyrin cores represent minima on the potential energy surfaces of both H(2)TFcP and MTFcP. The degree of non-planarity is central-metal dependent and follows the trend: ZnTFcP < H(2)TFcP approximately CuTFcP < CoTFcP < NiTFcP. In all cases, a set of occupied, predominantly ferrocene-based molecular orbitals were found between the highest occupied and the lowest unoccupied, predominantly porphyrin-based molecular orbitals. The vertical excitation energies of H(2)TFcP were calculated at the TDDFT level and confirm the presence of numerous predominantly metal-to-ligand charge-transfer bands coupled via configurational interaction with expected intra-ligand pi-pi* transitions.

  17. Evidence That GH115 α-Glucuronidase Activity, Which Is Required to Degrade Plant Biomass, Is Dependent on Conformational Flexibility*

    PubMed Central

    Rogowski, Artur; Baslé, Arnaud; Farinas, Cristiane S.; Solovyova, Alexandra; Mortimer, Jennifer C.; Dupree, Paul; Gilbert, Harry J.; Bolam, David N.

    2014-01-01

    The microbial degradation of the plant cell wall is an important biological process that is highly relevant to environmentally significant industries such as the bioenergy and biorefining sectors. A major component of the wall is glucuronoxylan, a β1,4-linked xylose polysaccharide that is decorated with α-linked glucuronic and/or methylglucuronic acid (GlcA/MeGlcA). Recently three members of a glycoside hydrolase family, GH115, were shown to hydrolyze MeGlcA side chains from the internal regions of xylan, an activity that has not previously been described. Here we show that a dominant member of the human microbiota, Bacteroides ovatus, contains a GH115 enzyme, BoAgu115A, which displays glucuronoxylan α-(4-O-methyl)-glucuronidase activity. The enzyme is significantly more active against substrates in which the xylose decorated with GlcA/MeGlcA is flanked by one or more xylose residues. The crystal structure of BoAgu115A revealed a four-domain protein in which the active site, comprising a pocket that abuts a cleft-like structure, is housed in the second domain that adopts a TIM barrel-fold. The third domain, a five-helical bundle, and the C-terminal β-sandwich domain make inter-chain contacts leading to protein dimerization. Informed by the structure of the enzyme in complex with GlcA in its open ring form, in conjunction with mutagenesis studies, the potential substrate binding and catalytically significant amino acids were identified. Based on the catalytic importance of residues located on a highly flexible loop, the enzyme is required to undergo a substantial conformational change to form a productive Michaelis complex with glucuronoxylan. PMID:24214982

  18. Large area silicon sheet by EFG

    NASA Technical Reports Server (NTRS)

    Kalejs, J. P.

    1982-01-01

    Work carried out on the JPL Flat Plate Solar Array Project, for the purpose of developing a method for silicon ribbon production by Edge-defined Film-fed Growth (EEG) for use as low-cost substrate material in terrestrial solar cell manufacture, is described. A multiple ribbon furnace unit that is designed to operate on a continuous basis for periods of at least one week, with melt replenishment and automatic ribbon width control, and to produce silicon sheet at a rate of one square meter per hour, was constructed. Program milestones set for single ribbon furnace operation to demonstrate basic EEG system capabilities with respect to growth speed, thickness and cell performance were achieved for 10 cm wide ribbon: steady-state growth at 4 cm/min and 200 micron thickness over periods of an hour and longer was made routine, and a small area cell efficiency of 13+% demonstrated. Large area cells of average efficiency of 10 to 11%, with peak values of 11 to 12% were also achieved. The integration of these individual performance levels into multiple ribbon furnace operation was not accomplished.

  19. Targeted flight opportunities with large area collectors

    NASA Technical Reports Server (NTRS)

    Mackinnon, I. D. R.

    1986-01-01

    A major factor in the stratospheric collection process is the relative density of particles at the collection altitude. With current aircraft-borne collector plate geometries, one potential extraterrestrial particle of about 10 micron diameter is collected approximately every hour. However, a new design for the collector plate, termed the Large Area Collector (LAC), allows a factor of 10 improvement in collection efficiency over current conventional geometry. The implementation of LAC design on future stratospheric collection flights will provide many opportunities for additional data on both terrestrial and extraterrestrial phenomena. With the improvement in collection efficiency, LAC's may provide a suitable number of potential extraterrestrial particles in one short flight of between 4 and 8 hours duration. Alternatively, total collection periods of approximately 40 hours enhance the probability that rare particles can be retrieved from the stratosphere. This latter approach is of great value for the cosmochemist who may wish to perform sophisticated analyses on interplanetary dust greater than a picogram. The former approach, involving short duration flights, may also provide invaluable data on the source of many extraterrestrial particles. The time dependence of particle entry to the collection altitude is an important parameter which may be correlated with specific global events (e.g., meteoroid streams) provided the collection time is known to an accuracy of 2 hours.

  20. Large area atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  1. FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

    SciTech Connect

    Nolan, P. L.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Abdo, A. A.; Ackermann, M.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Belfiore, A.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Bastieri, D.; Bignami, G. F. E-mail: Gino.Tosti@pg.infn.it E-mail: tburnett@u.washington.edu; and others

    2012-04-01

    We present the second catalog of high-energy {gamma}-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely {gamma}-ray-producing source classes.

  2. Large area silicon sheet by EFG

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Progress was made in improving ribbon flatness and reducing stress, and in raising cell performance for 10 cm wide ribbon grown in single cartridge EFG furnaces. Optimization of growth conditions resulted in improved ribbon thickness uniformity at a thickness of 200 micron, grown at 4 cm/minute, and growth at this target speed is routinely achieved over periods of the order of one hour or more. With the improved ribbon flatness, fabrication of large area (50 cm2) cells is now possible, and 10 to 11% efficiencies were demonstrated on ribbon grown at 3.5 to 4 cm/minute. Factors limiting performance of the existing multiple ribbon furnace were identified, and growth system improvements implemented to help raise throughput rates and the time percentage of simultaneous three-ribbon growth. However, it is evident that major redesign of this furnace would be needed to overcome shortfalls in its ability to achieve the Technical Features Demonstration goals of 1980. It was decided to start construction of a new multiple ribbon furnace and to incorporate the desired improvements into its design. The construction of this furnace is completed.

  3. Fermi Large Area Telescope Second Source Catalog

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M; Allafort, A.; Antolini, E; Bonnell, J.; Cannon, A.; Celik O.; Corbet, R.; Davis, D. S.; DeCesar, M. E.; Ferrara, E. C.; Gehrels, N.; Harding, A. K.; Hays, E.; Johnson, T. E.; McConville, W.; McEnery, J. E; Perkins, J. S.; Racusin, J. L; Scargle, J. D.; Stephens, T. E.; Thompson, D. J.; Troja, E.

    2012-01-01

    We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24-month period. The Second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in 5 energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 11eV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely gamma-ray-producing source classes.

  4. The Large Area Pulsed Solar Simulator (LAPSS)

    NASA Technical Reports Server (NTRS)

    Mueller, R. L.

    1994-01-01

    The Large Area Pulsed Solar Simulator (LAPSS) has been installed at JPL. It is primarily intended to be used to illuminate and measure the electrical performance of photovoltaic devices. The simulator, originally manufactured by Spectrolab, Sylmar, CA, occupies an area measuring about 3 m wide x 12 m long. The data acquisition and data processing subsystems have been modernized. Tests on the LAPSS performance resulted in better than plus or minus 2 percent uniformity of irradiance at the test plane and better than plus or minus 0.3 percent measurement repeatability after warm-up. Glass absorption filters reduce the ultraviolet light emitted from the xenon flash lamps. This results in a close match to three different standard airmass zero and airmass 1.5 spectral irradiances. The 2-ms light pulse prevents heating of the device under test, resulting in more reliable temperature measurements. Overall, excellent electrical performance measurements have been made of many different types and sizes of photovoltaic devices. Since the original printing of this publication, in 1993, the LAPSS has been operational and new capabilities have been added. This revision includes a new section relating to the installation of a method to measure the I-V curve of a solar cell or array exhibiting a large effective capacitance. Another new section has been added relating to new capabilities for plotting single and multiple I-V curves, and for archiving the I-V data and test parameters. Finally, a section has been added regarding the data acquisition electronics calibration.

  5. Ligand Docking to Intermediate and Close-To-Bound Conformers Generated by an Elastic Network Model Based Algorithm for Highly Flexible Proteins.

    PubMed

    Kurkcuoglu, Zeynep; Doruker, Pemra

    2016-01-01

    Incorporating receptor flexibility in small ligand-protein docking still poses a challenge for proteins undergoing large conformational changes. In the absence of bound structures, sampling conformers that are accessible by apo state may facilitate docking and drug design studies. For this aim, we developed an unbiased conformational search algorithm, by integrating global modes from elastic network model, clustering and energy minimization with implicit solvation. Our dataset consists of five diverse proteins with apo to complex RMSDs 4.7-15 Å. Applying this iterative algorithm on apo structures, conformers close to the bound-state (RMSD 1.4-3.8 Å), as well as the intermediate states were generated. Dockings to a sequence of conformers consisting of a closed structure and its "parents" up to the apo were performed to compare binding poses on different states of the receptor. For two periplasmic binding proteins and biotin carboxylase that exhibit hinge-type closure of two dynamics domains, the best pose was obtained for the conformer closest to the bound structure (ligand RMSDs 1.5-2 Å). In contrast, the best pose for adenylate kinase corresponded to an intermediate state with partially closed LID domain and open NMP domain, in line with recent studies (ligand RMSD 2.9 Å). The docking of a helical peptide to calmodulin was the most challenging case due to the complexity of its 15 Å transition, for which a two-stage procedure was necessary. The technique was first applied on the extended calmodulin to generate intermediate conformers; then peptide docking and a second generation stage on the complex were performed, which in turn yielded a final peptide RMSD of 2.9 Å. Our algorithm is effective in producing conformational states based on the apo state. This study underlines the importance of such intermediate states for ligand docking to proteins undergoing large transitions. PMID:27348230

  6. Ligand Docking to Intermediate and Close-To-Bound Conformers Generated by an Elastic Network Model Based Algorithm for Highly Flexible Proteins

    PubMed Central

    Kurkcuoglu, Zeynep; Doruker, Pemra

    2016-01-01

    Incorporating receptor flexibility in small ligand-protein docking still poses a challenge for proteins undergoing large conformational changes. In the absence of bound structures, sampling conformers that are accessible by apo state may facilitate docking and drug design studies. For this aim, we developed an unbiased conformational search algorithm, by integrating global modes from elastic network model, clustering and energy minimization with implicit solvation. Our dataset consists of five diverse proteins with apo to complex RMSDs 4.7–15 Å. Applying this iterative algorithm on apo structures, conformers close to the bound-state (RMSD 1.4–3.8 Å), as well as the intermediate states were generated. Dockings to a sequence of conformers consisting of a closed structure and its “parents” up to the apo were performed to compare binding poses on different states of the receptor. For two periplasmic binding proteins and biotin carboxylase that exhibit hinge-type closure of two dynamics domains, the best pose was obtained for the conformer closest to the bound structure (ligand RMSDs 1.5–2 Å). In contrast, the best pose for adenylate kinase corresponded to an intermediate state with partially closed LID domain and open NMP domain, in line with recent studies (ligand RMSD 2.9 Å). The docking of a helical peptide to calmodulin was the most challenging case due to the complexity of its 15 Å transition, for which a two-stage procedure was necessary. The technique was first applied on the extended calmodulin to generate intermediate conformers; then peptide docking and a second generation stage on the complex were performed, which in turn yielded a final peptide RMSD of 2.9 Å. Our algorithm is effective in producing conformational states based on the apo state. This study underlines the importance of such intermediate states for ligand docking to proteins undergoing large transitions. PMID:27348230

  7. Fermi Large Area Telescope Third Source Catalog

    NASA Astrophysics Data System (ADS)

    Acero, F.; Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonino, R.; Bottacini, E.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; DeKlotz, M.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Dubois, R.; Dumora, D.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Iafrate, G.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Katsuta, J.; Kuss, M.; La Mura, G.; Landriu, D.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mirabal, N.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Romani, R. W.; Salvetti, D.; Sánchez-Conde, M.; Saz Parkinson, P. M.; Schulz, A.; Siskind, E. J.; Smith, D. A.; Spada, F.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Van Klaveren, B.; Vianello, G.; Winer, B. L.; Wood, K. S.; Wood, M.; Zimmer, S.; Fermi-LAT Collaboration

    2015-06-01

    We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100 MeV-300 GeV range. Based on the first 4 yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse γ-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources above 4σ significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is ˜3% at 1 GeV.

  8. Large Area Lunar Dust Flux Measurement Instrument

    NASA Technical Reports Server (NTRS)

    Corsaro, R.; Giovane, F.; Liou, Jer-Chyi; Burchell, M.; Stansbery, Eugene; Lagakos, N.

    2009-01-01

    The instrument under development is designed to characterize the flux and size distribution of the lunar micrometeoroid and secondary ejecta environment. When deployed on the lunar surface, the data collected will benefit fundamental lunar science as well as enabling more reliable impact risk assessments for human lunar exploration activities. To perform this task, the instrument requirements are demanding. It must have as large a surface area as possible to sample the very sparse population of the larger potentially damage-inducing micrometeorites. It must also have very high sensitivity to enable it to measure the flux of small (<10 micron) micrometeorite and secondary ejecta dust particles. To be delivered to the lunar surface, it must also be very low mass, rugged and stow compactly. The instrument designed to meet these requirements is called FOMIS. It is a large-area thin film under tension (i.e. a drum) with multiple fiber optic displacement (FOD) sensors to monitor displacements of the film. This sensor was chosen since it can measure displacements over a wide dynamic range: 1 cm to sub-Angstrom. A prototype system was successfully demonstrated using the hypervelocity impact test facility at the University of Kent (Canterbury, UK). Based on these results, the prototype system can detect hypervelocity (approx.5 km/s) impacts by particles as small as 2 microns diameter. Additional tests using slow speeds find that it can detect secondary ejecta particles (which do not penetrate the film) with momentums as small as 15 pico-gram 100m/s, or nominally 5 microns diameter at 100 m/s.

  9. Large-area mapping of biodiversity

    USGS Publications Warehouse

    Scott, J.M.; Jennings, M.D.

    1998-01-01

    The age of discovery, description, and classification of biodiversity is entering a new phase. In responding to the conservation imperative, we can now supplement the essential work of systematics with spatially explicit information on species and assemblages of species. This is possible because of recent conceptual, technical, and organizational progress in generating synoptic views of the earth's surface and a great deal of its biological content, at multiple scales of thematic as well as geographic resolution. The development of extensive spatial data on species distributions and vegetation types provides us with a framework for: (a) assessing what we know and where we know it at meso-scales, and (b) stratifying the biological universe so that higher-resolution surveys can be more efficiently implemented, coveting, for example, geographic adequacy of specimen collections, population abundance, reproductive success, and genetic dynamics. The land areas involved are very large, and the questions, such as resolution, scale, classification, and accuracy, are complex. In this paper, we provide examples from the United States Gap Analysis Program on the advantages and limitations of mapping the occurrence of terrestrial vertebrate species and dominant land-cover types over large areas as joint ventures and in multi-organizational partnerships, and how these cooperative efforts can be designed to implement results from data development and analyses as on-the-ground actions. Clearly, new frameworks for thinking about biogeographic information as well as organizational cooperation are needed if we are to have any hope of documenting the full range of species occurrences and ecological processes in ways meaningful to their management. The Gap Analysis experience provides one model for achieving these new frameworks.

  10. Large Area X-ray Spectroscopy Mission

    NASA Technical Reports Server (NTRS)

    Tananbaum, Harvey

    1996-01-01

    The Large Area X-ray Spectroscopy (LAXS) mission study concept has evolved strongly over the last year culminating in the merging of LAXS with the Goddard Space Flight Center (GSFC) proposal for a similar mission, the Next Generation X-ray Observatory (NGXO, PI: Nick White). The resulting merger, re-named the High Throughput X-rays Spectroscopy (HTXS) Mission has also expanded by the inclusion of another SAO proposed new mission concept proposal, the Hard X-Ray Telescope (PI: Paul Gorenstein). The resultant multi-instrument mission retains much of heritage from the LAXS proposal, including the use of multiple satellites for robustness. These mergers resulted from a series of contacts between various team members, via e-mail, telecons, and in-person meetings. The impetus for the mergers was the fundamental similarity between the missions, and the recognition that all three proposal teams had significant contributions to make in the effort to define the next stage in the X-ray exploration of the universe. We have enclosed four items that represent some of the work that has occurred during the first year of the study: first, a presentation at the Leicester meeting, second a presentation that was made to Dan Goldin following the merging of LAXS and NGXO, third a copy of the first announcement for the Workshop, and finally the interim report that was prepared by the HTXS study team towards the end of the first year. This last document provides the foundation for the HTXS Technology Roadmap that is being generated. The HTXS roadmap will define the near-term goals that the merged mission must achieve over the next few years. A web site has been developed and populated that contains much of the material that has been generated over the past year.

  11. CC/DFT Route toward Accurate Structures and Spectroscopic Features for Observed and Elusive Conformers of Flexible Molecules: Pyruvic Acid as a Case Study.

    PubMed

    Barone, Vincenzo; Biczysko, Malgorzata; Bloino, Julien; Cimino, Paola; Penocchio, Emanuele; Puzzarini, Cristina

    2015-09-01

    The structures and relative stabilities as well as the rotational and vibrational spectra of the three low-energy conformers of pyruvic acid (PA) have been characterized using a state-of-the-art quantum-mechanical approach designed for flexible molecules. By making use of the available experimental rotational constants for several isotopologues of the most stable PA conformer, Tc-PA, the semiexperimental equilibrium structure has been derived. The latter provides a reference for the pure theoretical determination of the equilibrium geometries for all conformers, thus confirming for these structures an accuracy of 0.001 Å and 0.1 deg for bond lengths and angles, respectively. Highly accurate relative energies of all conformers (Tc-, Tt-, and Ct-PA) and of the transition states connecting them are provided along with the thermodynamic properties at low and high temperatures, thus leading to conformational enthalpies accurate to 1 kJ mol(-1). Concerning microwave spectroscopy, rotational constants accurate to about 20 MHz are provided for the Tt- and Ct-PA conformers, together with the computed centrifugal-distortion constants and dipole moments required to simulate their rotational spectra. For Ct-PA, vibrational frequencies in the mid-infrared region accurate to 10 cm(-1) are reported along with theoretical estimates for the transitions in the near-infrared range, and the corresponding infrared spectrum including fundamental transitions, overtones, and combination bands has been simulated. In addition to the new data described above, theoretical results for the Tc- and Tt-PA conformers are compared with all available experimental data to further confirm the accuracy of the hybrid coupled-cluster/density functional theory (CC/DFT) protocol applied in the present study. Finally, we discuss in detail the accuracy of computational models fully based on double-hybrid DFT functionals (mainly at the B2PLYP/aug-cc-pVTZ level) that avoid the use of very expensive CC

  12. CC/DFT Route toward Accurate Structures and Spectroscopic Features for Observed and Elusive Conformers of Flexible Molecules: Pyruvic Acid as a Case Study.

    PubMed

    Barone, Vincenzo; Biczysko, Malgorzata; Bloino, Julien; Cimino, Paola; Penocchio, Emanuele; Puzzarini, Cristina

    2015-09-01

    The structures and relative stabilities as well as the rotational and vibrational spectra of the three low-energy conformers of pyruvic acid (PA) have been characterized using a state-of-the-art quantum-mechanical approach designed for flexible molecules. By making use of the available experimental rotational constants for several isotopologues of the most stable PA conformer, Tc-PA, the semiexperimental equilibrium structure has been derived. The latter provides a reference for the pure theoretical determination of the equilibrium geometries for all conformers, thus confirming for these structures an accuracy of 0.001 Å and 0.1 deg for bond lengths and angles, respectively. Highly accurate relative energies of all conformers (Tc-, Tt-, and Ct-PA) and of the transition states connecting them are provided along with the thermodynamic properties at low and high temperatures, thus leading to conformational enthalpies accurate to 1 kJ mol(-1). Concerning microwave spectroscopy, rotational constants accurate to about 20 MHz are provided for the Tt- and Ct-PA conformers, together with the computed centrifugal-distortion constants and dipole moments required to simulate their rotational spectra. For Ct-PA, vibrational frequencies in the mid-infrared region accurate to 10 cm(-1) are reported along with theoretical estimates for the transitions in the near-infrared range, and the corresponding infrared spectrum including fundamental transitions, overtones, and combination bands has been simulated. In addition to the new data described above, theoretical results for the Tc- and Tt-PA conformers are compared with all available experimental data to further confirm the accuracy of the hybrid coupled-cluster/density functional theory (CC/DFT) protocol applied in the present study. Finally, we discuss in detail the accuracy of computational models fully based on double-hybrid DFT functionals (mainly at the B2PLYP/aug-cc-pVTZ level) that avoid the use of very expensive CC

  13. Graphene-based large area dye-sensitized solar cell modules

    NASA Astrophysics Data System (ADS)

    Casaluci, Simone; Gemmi, Mauro; Pellegrini, Vittorio; di Carlo, Aldo; Bonaccorso, Francesco

    2016-02-01

    We demonstrate spray coating of graphene ink as a viable method for large-area fabrication of graphene-based dye-sensitized solar cell (DSSC) modules. A graphene-based ink produced by liquid phase exfoliation of graphite is spray coated onto a transparent conductive oxide substrate to realize a large area (>90 cm2) semi-transparent (transmittance 44%) counter-electrode (CE) replacing platinum, the standard CE material. The graphene-based CE is successfully integrated in a large-area (43.2 cm2 active area) DSSC module achieving a power conversion efficiency of 3.5%. The approach demonstrated here paves the way to all-printed, flexible, and transparent graphene-based large-area and cost-effective photovoltaic devices on arbitrary substrates.

  14. High resolution crystal structures of triosephosphate isomerase complexed with its suicide inhibitors: The conformational flexibility of the catalytic glutamate in its closed, liganded active site

    PubMed Central

    Venkatesan, Rajaram; Alahuhta, Markus; Pihko, Petri M; Wierenga, Rik K

    2011-01-01

    The key residue of the active site of triosephosphate isomerase (TIM) is the catalytic glutamate, which is proposed to be important (i) as a catalytic base, for initiating the reaction, as well as (ii) for the subsequent proton shuttling steps. The structural properties of this glutamate in the liganded complex have been investigated by studying the high resolution crystal structures of typanosomal TIM, complexed with three suicide inhibitors: (S)-glycidol phosphate ((S)-GOP, at 0.99 Å resolution), (R)-glycidol phosphate, ((R)-GOP, at 1.08 Å resolution), and bromohydroxyacetone phosphate (BHAP, at 1.97 Å resolution). The structures show that in the (S)-GOP active site this catalytic glutamate is in the well characterized, competent conformation. However, an unusual side chain conformation is observed in the (R)-GOP and BHAP complexes. In addition, Glu97, salt bridged to the catalytic lysine in the competent active site, adopts an unusual side chain conformation in these two latter complexes. The higher chemical reactivity of (S)-GOP compared with (R)-GOP, as known from solution studies, can be understood: the structures indicate that in the case of (S)-GOP, Glu167 can attack the terminal carbon of the epoxide in a stereoelectronically favored, nearly linear O–C–O arrangement, but this is not possible for the (R)-GOP isomer. These structures confirm the previously proposed conformational flexibility of the catalytic glutamate in its closed, liganded state. The importance of this conformational flexibility for the proton shuttling steps in the TIM catalytic cycle, which is apparently achieved by a sliding motion of the side chain carboxylate group above the enediolate plane, is also discussed. PMID:21633986

  15. Gamma-Ray Large Area Space Telescope- GLAST Mission Overview

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander A.

    2007-01-01

    This viewgraph presentation reviews the Gamma-ray Large Area Space Telescope (GLAST), and the instrumentation that will be on the spacecraft: Large Area Telescope (LAT) and GLAST Burst Monitor (GBM). The presentation revierws in detail the LAT instrument.

  16. Coordination chemistry of conformation-flexible 1,2,3,4,5,6-cyclohexanehexacarboxylate: trapping various conformations in metal-organic frameworks.

    PubMed

    Wang, Jing; Lin, Zhuo-Jia; Ou, Yong-Cong; Shen, Yong; Herchel, Radovan; Tong, Ming-Liang

    2008-01-01

    To study the conformations of 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H(6)L), eleven new coordination polymers have been isolated from hydrothermal reactions of different metal salts with 1e,2a,3e,4a,5e,6a-cyclohexanehexacarboxylic acid (3e+3a, H(6)L(I)) and characterized. They are [Cd(12)(mu(6)-L(II))(mu(10)-L(II))(3)(mu-H(2)O)(6)(H(2)O)(6)]16.5 H(2)O (1), Na(12)[Cd(6)(mu(6)-L(II))(mu(6)-L(III))(3)]27 H(2)O (2), [Cd(3)(mu(13)-L(II))(mu-H(2)O)] (3), [Cd(3)(mu(6)-L(III))(2,2'-bpy)(3)(H(2)O)(3)]2 H(2)O (4), [Cd(4)(mu(4)-L(VI))(2)(4,4'-Hbpy)(4)(4,4'-bpy)(2)(H(2)O)(4)]9.5 H(2)O (5), [Cd(2)(mu(6)-L(II))(4,4'-Hbpy)(2)(H(2)O)(10)]5 H(2)O (6), [Cd(3)(mu(11)-L(VI))(H(2)O)(3)] (7), [M(3)(mu(9)-L(II))(H(2)O)(6)] (M=Mn (8), Fe (9), and Ni (10)), and [Ni(4)(OH)(2)(mu(10)-L(II))(4,4'-bpy)(H(2)O)(4)]6 H(2)O (11). Three new conformations of 1,2,3,4,5,6-cyclohexanehexacarboxylate, 6e (L(II)), 4e+2a (L(III)) and 5e+1a (L(VI)), have been derived from the conformational conversions of L(I) and trapped in these complexes by controlling the conditions of the hydrothermal systems. Complexes 1 and 2 have three-dimensional (3D) coordination frameworks with nanoscale cages and are obtained at relatively low temperatures. A quarter of the L(I) ligands undergo a conformational transformation into L(II) while the others are transformed into L(III) in the presence of NaOH in 2, while all of the L(I) are transformed into L(II) in the absence of NaOH in 1. Complex 3 has a 3D condensed coordination framework, which was obtained under similar reaction conditions as 1, but at a higher temperature. The addition of 2,2'-bipyridine (2,2'-bpy) or 4,4'-bipyridine (4,4'-bpy) to the hydrothermal system as an auxiliary ligand also induces the conformational transformation of H(6)L(I). A new L(VI) conformation has been trapped in complexes 4-7 under different conditions. Complex 4 has a 3D microporous supramolecular network constructed from a 2D L(III)-bridged coordination layer structure by pi

  17. Effect of Ca2+-Mg2+ exchange on the flexibility and/or conformation of the small domain in monomeric actin.

    PubMed

    Nyitrai, M; Hild, G; Lakos, Z; Somogyi, B

    1998-05-01

    A fluorescence resonance energy transfer (FRET) parameter, f' (defined as the average transfer efficiency, (E), normalized by the actual fluorescence intensity of the donor in the presence of acceptor, F(DA)), was previously shown to be capable of monitoring both changes in local flexibility of the protein matrix and major conformational transitions. The temperature profile of this parameter was used to detect the change of the protein flexibility in the small domain of the actin monomer (G-actin) upon the replacement of Ca2+ by Mg2+. The Cys-374 residue of the actin monomer was labeled with N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine (IAEDANS) to introduce a fluorescence donor and the Lys-61 residue with fluorescein-5-isothiocyanate (FITC) to serve as an acceptor. The f' increases with increasing temperature over the whole temperature range for Mg-G-actin. This parameter increases similarly in the case of Ca-G-actin up to 26 degrees C, whereas an opposite tendency appears above this temperature. These data indicate that there is a conformational change in Ca-G-actin above 26 degrees C that was not detected in the case of Mg-G-actin. In the temperature range between 6 degrees C and 26 degrees C the slope of the temperature profile of f' is the same for Ca-G-actin and Mg-G-actin, suggesting that the flexibility of the protein matrix between the two labels is identical in the two forms of actin.

  18. Llamas: Large-area microphone arrays and sensing systems

    NASA Astrophysics Data System (ADS)

    Sanz-Robinson, Josue

    Large-area electronics (LAE) provides a platform to build sensing systems, based on distributing large numbers of densely spaced sensors over a physically-expansive space. Due to their flexible, "wallpaper-like" form factor, these systems can be seamlessly deployed in everyday spaces. They go beyond just supplying sensor readings, but rather they aim to transform the wealth of data from these sensors into actionable inferences about our physical environment. This requires vertically integrated systems that span the entirety of the signal processing chain, including transducers and devices, circuits, and signal processing algorithms. To this end we develop hybrid LAE / CMOS systems, which exploit the complementary strengths of LAE, enabling spatially distributed sensors, and CMOS ICs, providing computational capacity for signal processing. To explore the development of hybrid sensing systems, based on vertical integration across the signal processing chain, we focus on two main drivers: (1) thin-film diodes, and (2) microphone arrays for blind source separation: 1) Thin-film diodes are a key building block for many applications, such as RFID tags or power transfer over non-contact inductive links, which require rectifiers for AC-to-DC conversion. We developed hybrid amorphous / nanocrystalline silicon diodes, which are fabricated at low temperatures (<200 °C) to be compatible with processing on plastic, and have high current densities (5 A/cm2 at 1 V) and high frequency operation (cutoff frequency of 110 MHz). 2) We designed a system for separating the voices of multiple simultaneous speakers, which can ultimately be fed to a voice-command recognition engine for controlling electronic systems. On a device level, we developed flexible PVDF microphones, which were used to create a large-area microphone array. On a circuit level we developed localized a-Si TFT amplifiers, and a custom CMOS IC, for system control, sensor readout and digitization. On a signal processing

  19. An examination of polymorphic stability and molecular conformational flexibility as a function of crystal size associated with the nucleation and growth of benzophenone.

    PubMed

    Hammond, Robert B; Pencheva, Klimentina; Roberts, Kevin J

    2007-01-01

    The polymorphic behaviour of the aromatic ketone, benzophenone, which is a conformationally flexible molecule and forms crystal structures dominated by van der Waals intermolecular interactions, is examined. Crystallization of this material from the undercooled molten state yields the two known polymorphic forms, i.e. the stable alpha-form and the metastable beta-form. The relative, energetic stabilities are examined using both crystal lattice and molecular conformational modelling techniques. Examination of nano-sized faceted molecular clusters of these forms, with cluster sizes ranging from 3 to 100 molecules, reveals that at very small cluster size (< 5 molecules) the relative energetic stability of clusters representative for the two forms become very similar, indicating that for high melting undercooling (i.e. small critical cluster size for nucleation) crystallization of the metastable beta-phase becomes more likely. Detailed analysis of the variation in molecular conformations within the simulated molecular clusters reveals more disordered three-dimensional structures at small compared to larger cluster sizes. The conformational disorder was found to be higher for the metastable beta-form. This observation, together with the lower stability of clusters for this form is indicative of the difficulty in achieving crystallization of the metastable beta-form from the melt, which requires a considerable undercooling.

  20. The conformational flexibility of nucleic acid bases paired in gas phase: A Car-Parrinello molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Xiao, Shiyan; Liang, Haojun

    2012-05-01

    The flexibilities of pyrimidine and imidazole rings in the paired nucleobases are investigated using Car-Parrinello molecular dynamics simulation in gas phase. The pairing influence on the stiffness of rings is analyzed based on the molecular structure of the nucleobases and constraints caused by pairing. We prove that the flexibilities of pyrimidine rings in isolated state have subtle correlation with the degree of aromaticity of the rings. The pairings in nucleic base pairs cause the rings to be more rigid for G, T, and U but more flexible for A and the same for C.

  1. Fabrication of large area nanostructures with surface modified silica spheres

    NASA Astrophysics Data System (ADS)

    Kang, Kwang-Sun

    2014-03-01

    Surface modification of silica spheres with 3-(trimethoxysilyl)propylmethacrylate (TMSPM) has been performed at ambient condition. However, the FTIR spectra and field emission scanning electron microscope (FESEM) images show no evidence of the surface modification. The reaction temperatures were varied from 60 to 80 °C with various reaction periods. Small absorption shoulder of the CO stretching vibration was at 1700 cm-1, and slightly increased with the increase of the reaction time at 60 °C. The clear absorption peak appeared at 1698 cm-1 for the spheres reacted for 80 min at 70 °C and shifted toward 1720 cm-1 with the increase the reaction time. Strong absorption peak showed at 1698 cm-1 and shifted toward 1725 cm-1 with the increase of the reaction time at 80 °C. The spheres were dispersed to methanol and added photoinitiator (Irgacure-184). The solution was poured to a patterned glass substrate and exposed to the 254 nm UV-light during a self-assembly process. A large area and crack-free silica sphere film was formed. To increase the mechanical stability, a cellulose acetate solution was spin-coated to the film. The film was lift-off from the glass substrate to analyze the surface nanostructures. The surface nanostructures were maintained, and the film is stable enough to use as a mold to duplicate the nanopattern and flexible.

  2. Correlated motion of protein subdomains and large-scale conformational flexibility of RecA protein filament

    NASA Astrophysics Data System (ADS)

    Yu, Garmay; A, Shvetsov; D, Karelov; D, Lebedev; A, Radulescu; M, Petukhov; V, Isaev-Ivanov

    2012-02-01

    Based on X-ray crystallographic data available at Protein Data Bank, we have built molecular dynamics (MD) models of homologous recombinases RecA from E. coli and D. radiodurans. Functional form of RecA enzyme, which is known to be a long helical filament, was approximated by a trimer, simulated in periodic water box. The MD trajectories were analyzed in terms of large-scale conformational motions that could be detectable by neutron and X-ray scattering techniques. The analysis revealed that large-scale RecA monomer dynamics can be described in terms of relative motions of 7 subdomains. Motion of C-terminal domain was the major contributor to the overall dynamics of protein. Principal component analysis (PCA) of the MD trajectories in the atom coordinate space showed that rotation of C-domain is correlated with the conformational changes in the central domain and N-terminal domain, that forms the monomer-monomer interface. Thus, even though C-terminal domain is relatively far from the interface, its orientation is correlated with large-scale filament conformation. PCA of the trajectories in the main chain dihedral angle coordinate space implicates a co-existence of a several different large-scale conformations of the modeled trimer. In order to clarify the relationship of independent domain orientation with large-scale filament conformation, we have performed analysis of independent domain motion and its implications on the filament geometry.

  3. Structural reassignment, absolute configuration, and conformation of hypurticin, a highly flexible polyacyloxy-6-heptenyl-5,6-dihydro-2H-pyran-2-one.

    PubMed

    Mendoza-Espinoza, José Alberto; López-Vallejo, Fabian; Fragoso-Serrano, Mabel; Pereda-Miranda, Rogelio; Cerda-García-Rojas, Carlos M

    2009-04-01

    The structural reassignment, absolute configuration, and conformational behavior of the highly flexible natural product hypurticin (pectinolide E), 6S-[3'S,5'R,6'S-triacetoxy-1Z-heptenyl]-5S-acetoxy-5,6-dihydro-2H-pyran-2-one (1), were ascertained by a molecular modeling protocol, which includes extensive conformational searching, geometry optimization by DFT B3LYP/DGDZVP calculations, and comparison between the theoretical (DFT) and experimental (1)H-(1)H NMR coupling constants. Hyptolide (2), a related cytotoxic 5,6-dihydro-2H-pyran-2-one that increased the S phase of the HeLa cell cycle, was employed as a reference substance to validate the theoretical protocol designed to characterize the 3D properties of compound 1. The related synthetic derivative, tri-O-acetyl-3,6-dideoxy-d-glucose diphenyldithioacetal (14), was prepared by a six-step reaction sequence starting from d-glucose and served as an enantiopure building block to reinforce the structural and configurational assignment of 1. This protocol proved to be an important tool for the structural characterization of highly flexible bioactive polyoxygenated natural products. PMID:19265396

  4. Can the conformation of flexible hydroxyl groups be constrained by simple NMR crystallography approaches? The case of the quercetin solid forms.

    PubMed

    Filip, Xenia; Filip, Claudiu

    2015-02-01

    Hydrogen atoms in systems with many flexible hydroxyl side-groups are difficult to be exactly located from experimental X-Ray diffraction and/or solid-state NMR data, thus often leading to wrong conclusions with respect to the hydrogen bonding network established in crystal lattice. A simple computational method is proposed in the present work to tackle this problem, which may be readily incorporated in conventional NMR crystallography protocols. The method is based on ranking all possible conformations of the flexible hydroxyls according to their lattice energy in crystalline environments. Its effectiveness is investigated on two distinct solid forms of quercetin, for which only two out of the five hydroxyl side-groups can be well constrained from experimental/theoretical data. For this purpose, first-principle quantum-mechanical computations were combined with calculations at the molecular mechanics (MM) level of theory, and previous ss-NMR and X-Ray diffraction data. To assess accuracy in ranking the identified conformers, tests have been performed first on quercetin dihydrate, for which an X-Ray single-crystal structure is available. The possibility of applying this method in a real NMR crystallography context has been investigated finally on anhydrous quercetin, for which only powder X-Ray crystal structure has been reported so far.

  5. Printable Solid-State Lithium-Ion Batteries: A New Route toward Shape-Conformable Power Sources with Aesthetic Versatility for Flexible Electronics.

    PubMed

    Kim, Se-Hee; Choi, Keun-Ho; Cho, Sung-Ju; Choi, Sinho; Park, Soojin; Lee, Sang-Young

    2015-08-12

    Forthcoming flexible/wearable electronic devices with shape diversity and mobile usability garner a great deal of attention as an innovative technology to bring unprecedented changes in our daily lives. From the power source point of view, conventional rechargeable batteries (one representative example is a lithium-ion battery) with fixed shapes and sizes have intrinsic limitations in fulfilling design/performance requirements for the flexible/wearable electronics. Here, as a facile and efficient strategy to address this formidable challenge, we demonstrate a new class of printable solid-state batteries (referred to as "PRISS batteries"). Through simple stencil printing process (followed by ultraviolet (UV) cross-linking), solid-state composite electrolyte (SCE) layer and SCE matrix-embedded electrodes are consecutively printed on arbitrary objects of complex geometries, eventually leading to fully integrated, multilayer-structured PRISS batteries with various form factors far beyond those achievable by conventional battery technologies. Tuning rheological properties of SCE paste and electrode slurry toward thixotropic fluid characteristics, along with well-tailored core elements including UV-cured triacrylate polymer and high boiling point electrolyte, is a key-enabling technology for the realization of PRISS batteries. This process/material uniqueness allows us to remove extra processing steps (related to solvent drying and liquid-electrolyte injection) and also conventional microporous separator membranes, thereupon enabling the seamless integration of shape-conformable PRISS batteries (including letters-shaped ones) into complex-shaped objects. Electrochemical behavior of PRISS batteries is elucidated via an in-depth analysis of cell impedance, which provides a theoretical basis to enable sustainable improvement of cell performance. We envision that PRISS batteries hold great promise as a reliable and scalable platform technology to open a new concept of cell

  6. Printable Solid-State Lithium-Ion Batteries: A New Route toward Shape-Conformable Power Sources with Aesthetic Versatility for Flexible Electronics.

    PubMed

    Kim, Se-Hee; Choi, Keun-Ho; Cho, Sung-Ju; Choi, Sinho; Park, Soojin; Lee, Sang-Young

    2015-08-12

    Forthcoming flexible/wearable electronic devices with shape diversity and mobile usability garner a great deal of attention as an innovative technology to bring unprecedented changes in our daily lives. From the power source point of view, conventional rechargeable batteries (one representative example is a lithium-ion battery) with fixed shapes and sizes have intrinsic limitations in fulfilling design/performance requirements for the flexible/wearable electronics. Here, as a facile and efficient strategy to address this formidable challenge, we demonstrate a new class of printable solid-state batteries (referred to as "PRISS batteries"). Through simple stencil printing process (followed by ultraviolet (UV) cross-linking), solid-state composite electrolyte (SCE) layer and SCE matrix-embedded electrodes are consecutively printed on arbitrary objects of complex geometries, eventually leading to fully integrated, multilayer-structured PRISS batteries with various form factors far beyond those achievable by conventional battery technologies. Tuning rheological properties of SCE paste and electrode slurry toward thixotropic fluid characteristics, along with well-tailored core elements including UV-cured triacrylate polymer and high boiling point electrolyte, is a key-enabling technology for the realization of PRISS batteries. This process/material uniqueness allows us to remove extra processing steps (related to solvent drying and liquid-electrolyte injection) and also conventional microporous separator membranes, thereupon enabling the seamless integration of shape-conformable PRISS batteries (including letters-shaped ones) into complex-shaped objects. Electrochemical behavior of PRISS batteries is elucidated via an in-depth analysis of cell impedance, which provides a theoretical basis to enable sustainable improvement of cell performance. We envision that PRISS batteries hold great promise as a reliable and scalable platform technology to open a new concept of cell

  7. Use of cysteine-reactive crosslinkers to probe conformational flexibility of human DJ-1 demonstrates that Glu18 mutations are dimers

    PubMed Central

    Prahlad, Janani; Hauser, David N.; Milkovic, Nicole M.; Cookson, Mark R.; Wilson, Mark A.

    2014-01-01

    The oxidation of a key cysteine residue (Cys106) in the parkinsonism-associated protein DJ-1 regulates its ability to protect against oxidative stress and mitochondrial damage. Cys106 interacts with a neighboring protonated Glu18 residue, stabilizing the Cys106-SO2− (sulfinic acid) form of DJ-1. To study this important post-translational modification, we previously designed several Glu18 mutations (E18N, E18D, E18Q) that alter the oxidative propensity of Cys106. However, recent results suggest these Glu18 mutations cause loss of DJ-1 dimerization, which would severely compromise the protein’s function. The purpose of this study was to conclusively determine the oligomerization state of these mutants using X-ray crystallography, NMR spectroscopy, thermal stability analysis, CD spectroscopy, sedimentation equilibrium ultracentrifugation, and crosslinking. We found that all of the Glu18 DJ-1 mutants were dimeric. Thiol crosslinking indicates that these mutant dimers are more flexible than the wild-type protein and can form multiple crosslinked dimeric species due to the transient exposure of cysteine residues that are inaccessible in the wild-type protein. The enhanced flexibility of Glu18 DJ-1 mutants provides a parsimonious explanation for their lower observed crosslinking efficiency in cells. In addition, thiol crosslinkers may have an underappreciated value as qualitative probes of protein conformational flexibility. PMID:24832775

  8. Large area x-ray detectors for cargo radiography

    NASA Astrophysics Data System (ADS)

    Bueno, C.; Albagli, D.; Bendahan, J.; Castleberry, D.; Gordon, C.; Hopkins, F.; Ross, W.

    2007-04-01

    Large area x-ray detectors based on phosphors coupled to flat panel amorphous silicon diode technology offer significant advances for cargo radiologic imaging. Flat panel area detectors provide large object coverage offering high throughput inspections to meet the high flow rate of container commerce. These detectors provide excellent spatial resolution when needed, and enhanced SNR through low noise electronics. If the resolution is reduced through pixel binning, further advances in SNR are achievable. Extended exposure imaging and frame averaging enables improved x-ray penetration of ultra-thick objects, or "select-your-own" contrast sensitivity at a rate many times faster than LDAs. The areal coverage of flat panel technology provides inherent volumetric imaging with the appropriate scanning methods. Flat panel area detectors have flexible designs in terms of electronic control, scintillator selection, pixel pitch, and frame rates. Their cost is becoming more competitive as production ramps up for the healthcare, nondestructive testing (NDT), and homeland protection industries. Typically used medical and industrial polycrystalline phosphor materials such as Gd2O2S:Tb (GOS) can be applied to megavolt applications if the phosphor layer is sufficiently thick to enhance x-ray absorption, and if a metal radiator is used to augment the quantum detection efficiency and reduce x-ray scatter. Phosphor layers ranging from 0.2-mm to 1-mm can be "sandwiched" between amorphous silicon flat panel diode arrays and metal radiators. Metal plates consisting of W, Pb or Cu, with thicknesses ranging from 0.25-mm to well over 1-mm can be used by covering the entire area of the phosphor plate. In some combinations of high density metal and phosphor layers, the metal plate provides an intensification of 25% in signal due to electron emission from the plate and subsequent excitation within the phosphor material. This further improves the SNR of the system.

  9. A large area cooled-CCD detector for electron microscopy

    NASA Astrophysics Data System (ADS)

    Faruqi, A. R.; Andrews, H. N.; Raeburn, C.

    1994-09-01

    Large area cooled-CCDs are an excellent medium for (indirectly) recording electron images and electron diffraction patterns in real time and for use in electron tomography; real-time imaging is extremely useful in making rapid adjustments in the electron microscope. CCDs provide high sensitivity (useful for minimising dosage to radiation-sensitive biological specimen), good resolution, stable performance, excellent dynamic range and linearity and a reasonably fast readout. We have built an electron imaging device based on the EEV 1152 by 814 pixel CCD which is controlled from a unix based SUN Sparestation operating under X-Windows. The incident 100 kV electrons are converted to visible light in a 0.5 mm thick YAG single crystal which is imaged through a lens on to the CCD. The CCD electronics is designed to be as flexible as possible and allows a wide variation in the readout speed to cater for the relatively fast application where readout noise is less critical and low readout noise applications where the extra few seconds of readout time are not significant. The CCD electronics is built in VME format which is controlled through a S-bus to VME driver. With two parallel channels of readout the whole image can be read out in ˜ 1 s (using the faster readout speed) with 16 bit precision and the image is displayed under X-Windows in a few seconds. The present readout works at 500 kHz and has a noise of ˜ 30 e rms per pixel. With a Peltier cooling device we can operate the CCD at ˜ -40°C which reduces the dark current adequately to allow exposures of up to several minutes. Several examples of patterns collected with the system on a Philips CM12 microscope will be presented.

  10. Uniformity of large-area bilayer graphene grown by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Sheng, Yuewen; Rong, Youmin; He, Zhengyu; Fan, Ye; Warner, Jamie H.

    2015-10-01

    Graphene grown by chemical vapor deposition (CVD) on copper foils is a viable method for large area films for transparent conducting electrode (TCE) applications. We examine the spatial uniformity of large area films on the centimeter scale when transferred onto both Si substrates with 300 nm oxide and flexible transparent polyethylene terephthalate substrates. A difference in the quality of graphene, as measured by the sheet resistance and transparency, is found for the areas at the edges of large sheets that depends on the supporting boat used for the CVD growth. Bilayer graphene is grown with uniform properties on the centimeter scale when a flat support is used for CVD growth. The flat support provides consistent delivery of precursor to the copper catalyst for graphene growth. These results provide important insights into the upscaling of CVD methods for growing high quality graphene and its transfer onto flexible substrates for potential applications as a TCE.

  11. Uniformity of large-area bilayer graphene grown by chemical vapor deposition.

    PubMed

    Sheng, Yuewen; Rong, Youmin; He, Zhengyu; Fan, Ye; Warner, Jamie H

    2015-10-01

    Graphene grown by chemical vapor deposition (CVD) on copper foils is a viable method for large area films for transparent conducting electrode (TCE) applications. We examine the spatial uniformity of large area films on the centimeter scale when transferred onto both Si substrates with 300 nm oxide and flexible transparent polyethylene terephthalate substrates. A difference in the quality of graphene, as measured by the sheet resistance and transparency, is found for the areas at the edges of large sheets that depends on the supporting boat used for the CVD growth. Bilayer graphene is grown with uniform properties on the centimeter scale when a flat support is used for CVD growth. The flat support provides consistent delivery of precursor to the copper catalyst for graphene growth. These results provide important insights into the upscaling of CVD methods for growing high quality graphene and its transfer onto flexible substrates for potential applications as a TCE. PMID:26349521

  12. Protein flexibility and conformational state: a comparison of collective vibrational modes of wild-type and D96N bacteriorhodopsin.

    PubMed

    Whitmire, S E; Wolpert, D; Markelz, A G; Hillebrecht, J R; Galan, J; Birge, R R

    2003-08-01

    Far infrared (FIR) spectral measurements of wild-type (WT) and D96N mutant bacteriorhodopsin thin films have been carried out using terahertz time domain spectroscopy as a function of hydration, temperature, and conformational state. The results are compared to calculated spectra generated via normal mode analyses using CHARMM. We find that the FIR absorbance is slowly increasing with frequency and without strong narrow features over the range of 2-60 cm(-1) and up to a resolution of 0.17 cm(-1). The broad absorption shifts in frequency with decreasing temperature as expected with a strongly anharmonic potential and in agreement with neutron inelastic scattering results. Decreasing hydration shifts the absorption to higher frequencies, possibly resulting from decreased coupling mediated by the interior water molecules. Ground-state FIR absorbances have nearly identical frequency dependence, with the mutant having less optical density than the WT. In the M state, the FIR absorbance of the WT increases whereas there is no change for D96N. These results represent the first measurement of FIR absorbance change as a function of conformational state.

  13. Smooth, seamless, and structured grid generation with flexibility in resolution distribution on a sphere based on conformal mapping and the spring dynamics method

    NASA Astrophysics Data System (ADS)

    Iga, Shin-ichi

    2015-09-01

    A generation method for smooth, seamless, and structured triangular grids on a sphere with flexibility in resolution distribution is proposed. This method is applicable to many fields that deal with a sphere on which the required resolution is not uniform. The grids were generated using the spring dynamics method, and adjustments were made using analytical functions. The mesh topology determined its resolution distribution, derived from a combination of conformal mapping factors: polar stereographic projection (PSP), Lambert conformal conic projection (LCCP), and Mercator projection (MP). Their combination generated, for example, a tropically fine grid that had a nearly constant high-resolution belt around the equator, with a gradual decrease in resolution distribution outside of the belt. This grid can be applied to boundary-less simulations of tropical meteorology. The other example involves a regionally fine grid with a nearly constant high-resolution circular region and a gradually decreasing resolution distribution outside of the region. This is applicable to regional atmospheric simulations without grid nesting. The proposed grids are compatible with computer architecture because they possess a structured form. Each triangle of the proposed grids was highly regular, implying a high local isotropy in resolution. Finally, the proposed grids were examined by advection and shallow water simulations.

  14. A unique 2-sulfated {beta}-galactan from the egg jelly of the sea urchin Glyptocidaris crenularis: conformation flexibility versus induction of the sperm acrosome reaction.

    PubMed

    Castro, Michelle O; Pomin, Vitor H; Santos, Livia L; Vilela-Silva, Ana-Cristina E S; Hirohashi, Noritaka; Pol-Fachin, Laércio; Verli, Hugo; Mourão, Paulo A S

    2009-07-10

    Sulfated polysaccharides from the egg jelly of sea urchins act as species-specific inducers of the sperm acrosome reaction, which is a rare molecular mechanism of carbohydrate-induced signal-transduction event in animal cells. The sea urchin polysaccharides differ in monosaccharide composition (l-fucose or l-galactose), glycosylation, and sulfation sites, but they are always in the alpha-anomeric configuration. Herein, structural analysis of the polysaccharide from the sea urchin Glyptocidaris crenularis surprisingly revealed a unique sulfated beta-d-galactan composed by (3-beta-d-Galp-2(OSO(3))-1-->3-beta-d-Galp-1)(n) repeating units. Subsequently, we used the G. crenularis galactan to compare different 2-sulfated polysaccharides as inducers of the acrosome reaction using homologous and heterologous sperm. We also tested the effect of chemically over-sulfated galactans. Intriguingly, the anomeric configuration of the glycosidic linkage rather than the monosaccharide composition (galactose or fucose) is the preferential structural requirement for the effect of these polysaccharides on sea urchin fertilization. Nuclear magnetic resonance and molecular dynamics indicate that sulfated alpha-galactan or alpha-fucan have less dynamic structural behavior, exhibiting fewer conformational populations, with an almost exclusive conformational state with glycosidic dihedral angles Phi/Psi = -102 degrees /131 degrees . The preponderant conformer observed in the sulfated alpha-galactan or alpha-fucan is not observed among populations in the beta-form despite its more flexible structure in solution. Possibly, a proper spatial arrangement is required for interaction of the sea urchin-sulfated polysaccharides with the specific sperm receptor.

  15. Adjustment of local conformational flexibility and accessible surface area alterations of Serine128 and Valine183 in mnemiopsin

    NASA Astrophysics Data System (ADS)

    Hakiminia, Forough; Molakarimi, Maryam; Khalifeh, Khosrow; Jahani, Zohreh; Sajedi, Reza H.; Ranjbar, Bijan

    2016-08-01

    We used a combination of experimental and bioinformatic studies to elucidate the importance of Serine128 and Valine183 on the activity and thermal stability of mnemiopsin 1 by substitution of S128 and V183 with glycine and threonine, respectively (S128G and V183T mutants). Luminescence emissions of S128G and V183T were reduced to 71.6% and 46.6% with respect to the original activity of the wild type protein. According to circular dichroism (CD) measurements, compactness of mutants decreased in comparison with wild type (WT) protein. Differential scanning calorimetry (DSC) indicated that Tm values of thermal unfolding are not changed significantly upon mutation. Herein, we suggest that the protein variants unfold through molecular association and intermediate states. Bioinformatic studies revealed that local fluctuation of residues in S128G increased with respect to WT protein. However, S128G mutation leads to increment of the accessible surface area of lysine188. Therefore, this change is thermodynamically favorable. Finally, both experimental and theoretical studies showed a delicate balance between all structural alterations, determining total conformational stability of the protein.

  16. Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy

    PubMed Central

    Kim, Dae-Hyeong; Ghaffari, Roozbeh; Lu, Nanshu; Wang, Shuodao; Lee, Stephen P.; Keum, Hohyun; D’Angelo, Robert; Klinker, Lauren; Su, Yewang; Lu, Chaofeng; Kim, Yun-Soung; Ameen, Abid; Li, Yuhang; Zhang, Yihui; de Graff, Bassel; Hsu, Yung-Yu; Liu, ZhuangJian; Ruskin, Jeremy; Xu, Lizhi; Lu, Chi; Omenetto, Fiorenzo G.; Huang, Yonggang; Mansour, Moussa; Slepian, Marvin J.; Rogers, John A.

    2012-01-01

    Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs that conformally wrap the epicardium, establishing robust contact without sutures, mechanical fixtures, tapes, or surgical adhesives. These multifunctional web devices exploit open, mesh layouts and mount on thin, bio-resorbable sheets of silk to facilitate handling in a way that yields, after dissolution, exceptionally low mechanical moduli and thicknesses. In vivo studies in rabbit and pig animal models demonstrate the effectiveness of these device webs for measuring and spatially mapping temperature, electrophysiological signals, strain, and physical contact in sheet and balloon-based systems that also have the potential to deliver energy to perform localized tissue ablation. PMID:23150574

  17. Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy.

    PubMed

    Kim, Dae-Hyeong; Ghaffari, Roozbeh; Lu, Nanshu; Wang, Shuodao; Lee, Stephen P; Keum, Hohyun; D'Angelo, Robert; Klinker, Lauren; Su, Yewang; Lu, Chaofeng; Kim, Yun-Soung; Ameen, Abid; Li, Yuhang; Zhang, Yihui; de Graff, Bassel; Hsu, Yung-Yu; Liu, Zhuangjian; Ruskin, Jeremy; Xu, Lizhi; Lu, Chi; Omenetto, Fiorenzo G; Huang, Yonggang; Mansour, Moussa; Slepian, Marvin J; Rogers, John A

    2012-12-01

    Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs that conformally wrap the epicardium, establishing robust contact without sutures, mechanical fixtures, tapes, or surgical adhesives. These multifunctional web devices exploit open, mesh layouts and mount on thin, bio-resorbable sheets of silk to facilitate handling in a way that yields, after dissolution, exceptionally low mechanical moduli and thicknesses. In vivo studies in rabbit and pig animal models demonstrate the effectiveness of these device webs for measuring and spatially mapping temperature, electrophysiological signals, strain, and physical contact in sheet and balloon-based systems that also have the potential to deliver energy to perform localized tissue ablation. PMID:23150574

  18. Large-area functionalized CVD graphene for work function matched transparent electrodes

    PubMed Central

    Bointon, Thomas H.; Jones, Gareth F.; De Sanctis, Adolfo; Hill-Pearce, Ruth; Craciun, Monica F.; Russo, Saverio

    2015-01-01

    The efficiency of flexible photovoltaic and organic light emitting devices is heavily dependent on the availability of flexible and transparent conductors with at least a similar workfunction to that of Indium Tin Oxide. Here we present the first study of the work function of large area (up to 9 cm2) FeCl3 intercalated graphene grown by chemical vapour deposition on Nickel, and demonstrate values as large as 5.1 eV. Upon intercalation, a charge density per graphene layer of 5 ⋅ 1013 ± 5 ⋅ 1012 cm−2 is attained, making this material an attractive platform for the study of plasmonic excitations in the infrared wavelength spectrum of interest to the telecommunication industry. Finally, we demonstrate the potential of this material for flexible electronics in a transparent circuit on a polyethylene naphthalate substrate. PMID:26548711

  19. Optical nano-woodpiles: large-area metallic photonic crystals and metamaterials

    NASA Astrophysics Data System (ADS)

    Ibbotson, Lindsey A.; Demetriadou, Angela; Croxall, Stephen; Hess, Ortwin; Baumberg, Jeremy J.

    2015-02-01

    Metallic woodpile photonic crystals and metamaterials operating across the visible spectrum are extremely difficult to construct over large areas, because of the intricate three-dimensional nanostructures and sub-50 nm features demanded. Previous routes use electron-beam lithography or direct laser writing but widespread application is restricted by their expense and low throughput. Scalable approaches including soft lithography, colloidal self-assembly, and interference holography, produce structures limited in feature size, material durability, or geometry. By multiply stacking gold nanowire flexible gratings, we demonstrate a scalable high-fidelity approach for fabricating flexible metallic woodpile photonic crystals, with features down to 10 nm produced in bulk and at low cost. Control of stacking sequence, asymmetry, and orientation elicits great control, with visible-wavelength band-gap reflections exceeding 60%, and with strong induced chirality. Such flexible and stretchable architectures can produce metamaterials with refractive index near zero, and are easily tuned across the IR and visible ranges.

  20. Large-area synthesis of high-quality and uniform monolayer WS2 on reusable Au foils

    PubMed Central

    Gao, Yang; Liu, Zhibo; Sun, Dong-Ming; Huang, Le; Ma, Lai-Peng; Yin, Li-Chang; Ma, Teng; Zhang, Zhiyong; Ma, Xiu-Liang; Peng, Lian-Mao; Cheng, Hui-Ming; Ren, Wencai

    2015-01-01

    Large-area monolayer WS2 is a desirable material for applications in next-generation electronics and optoelectronics. However, the chemical vapour deposition (CVD) with rigid and inert substrates for large-area sample growth suffers from a non-uniform number of layers, small domain size and many defects, and is not compatible with the fabrication process of flexible devices. Here we report the self-limited catalytic surface growth of uniform monolayer WS2 single crystals of millimetre size and large-area films by ambient-pressure CVD on Au. The weak interaction between the WS2 and Au enables the intact transfer of the monolayers to arbitrary substrates using the electrochemical bubbling method without sacrificing Au. The WS2 shows high crystal quality and optical and electrical properties comparable or superior to mechanically exfoliated samples. We also demonstrate the roll-to-roll/bubbling production of large-area flexible films of uniform monolayer, double-layer WS2 and WS2/graphene heterostructures, and batch fabrication of large-area flexible monolayer WS2 film transistor arrays. PMID:26450174

  1. Large-area synthesis of high-quality and uniform monolayer WS2 on reusable Au foils

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Liu, Zhibo; Sun, Dong-Ming; Huang, Le; Ma, Lai-Peng; Yin, Li-Chang; Ma, Teng; Zhang, Zhiyong; Ma, Xiu-Liang; Peng, Lian-Mao; Cheng, Hui-Ming; Ren, Wencai

    2015-10-01

    Large-area monolayer WS2 is a desirable material for applications in next-generation electronics and optoelectronics. However, the chemical vapour deposition (CVD) with rigid and inert substrates for large-area sample growth suffers from a non-uniform number of layers, small domain size and many defects, and is not compatible with the fabrication process of flexible devices. Here we report the self-limited catalytic surface growth of uniform monolayer WS2 single crystals of millimetre size and large-area films by ambient-pressure CVD on Au. The weak interaction between the WS2 and Au enables the intact transfer of the monolayers to arbitrary substrates using the electrochemical bubbling method without sacrificing Au. The WS2 shows high crystal quality and optical and electrical properties comparable or superior to mechanically exfoliated samples. We also demonstrate the roll-to-roll/bubbling production of large-area flexible films of uniform monolayer, double-layer WS2 and WS2/graphene heterostructures, and batch fabrication of large-area flexible monolayer WS2 film transistor arrays.

  2. Exploring the atomic structure and conformational flexibility of a 320 Å long engineered viral fiber using X-ray crystallography

    SciTech Connect

    Bhardwaj, Anshul; Casjens, Sherwood R.; Cingolani, Gino

    2014-02-01

    This study presents the crystal structure of a ∼320 Å long protein fiber generated by in-frame extension of its repeated helical coiled-coil core. Protein fibers are widespread in nature, but only a limited number of high-resolution structures have been determined experimentally. Unlike globular proteins, fibers are usually recalcitrant to form three-dimensional crystals, preventing single-crystal X-ray diffraction analysis. In the absence of three-dimensional crystals, X-ray fiber diffraction is a powerful tool to determine the internal symmetry of a fiber, but it rarely yields atomic resolution structural information on complex protein fibers. An 85-residue-long minimal coiled-coil repeat unit (MiCRU) was previously identified in the trimeric helical core of tail needle gp26, a fibrous protein emanating from the tail apparatus of the bacteriophage P22 virion. Here, evidence is provided that an MiCRU can be inserted in frame inside the gp26 helical core to generate a rationally extended fiber (gp26-2M) which, like gp26, retains a trimeric quaternary structure in solution. The 2.7 Å resolution crystal structure of this engineered fiber, which measures ∼320 Å in length and is only 20–35 Å wide, was determined. This structure, the longest for a trimeric protein fiber to be determined to such a high resolution, reveals the architecture of 22 consecutive trimerization heptads and provides a framework to decipher the structural determinants for protein fiber assembly, stability and flexibility.

  3. Plasma and Ion Sources in Large Area Coatings: A Review

    SciTech Connect

    Anders, Andre

    2005-02-28

    Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

  4. Large-area metallic photonic lattices for military applications.

    SciTech Connect

    Luk, Ting Shan

    2007-11-01

    In this project we developed photonic crystal modeling capability and fabrication technology that is scaleable to large area. An intelligent optimization code was developed to find the optimal structure for the desired spectral response. In terms of fabrication, an exhaustive survey of fabrication techniques that would meet the large area requirement was reduced to Deep X-ray Lithography (DXRL) and nano-imprint. Using DXRL, we fabricated a gold logpile photonic crystal in the <100> plane. For the nano-imprint technique, we fabricated a cubic array of gold squares. These two examples also represent two classes of metallic photonic crystal topologies, the connected network and cermet arrangement.

  5. Large area, low cost solar cell development and production readiness

    NASA Technical Reports Server (NTRS)

    Michaels, D.

    1982-01-01

    A process sequence for a large area ( or = 25 sq. cm) silicon solar cell was investigated. Generic cell choice was guided by the expected electron fluence, by the packing factors of various cell envelope designs onto each panel to provide needed voltage as well as current, by the weight constraints on the system, and by the cost goals of the contract.

  6. Large-area cryocooling for far-infrared telescopes

    NASA Astrophysics Data System (ADS)

    Hoang, Triem T.; O'Connell, Tamara A.; Ku, Jentung; Butler, C. D.; Swanson, Theodore D.

    2003-10-01

    Requirements for cryocooling of large-area heat sources begin to appear in studies of future space missions. Examples are the cooling of (i) the entire structure/mirror of large Far Infrared space telescopes to 4-40K and (ii) cryogenic thermal bus to maintain High Temperature Superconductor electronics to below 75K. The cryocooling system must provide robust/reliable operation and not cause significant vibration to the optical components. But perhaps the most challenging aspect of the system design is the removal of waste heat over a very large area. A cryogenic Loop Heat Pipe (C-LHP)/ cryocooler cooling system was developed with the ultimate goal of meeting the aforementioned requirements. In the proposed cooling concept, the C-LHP collected waste heat from a large-area heat source and then transported it to the cryocooler coldfinger for rejection. A proof-of-concept C-LHP test loop was constructed and performance tested in a vacuum chamber to demonstrate the feasibility of the proposed C-LHP to distribute the cryocooler cooling power over a large area. The test loop was designed to operate with any cryogenic working fluid such as Oxygen/Nitrogen (60-120K), Neon (28-40K), Hydrogen (18-30K), and Helium (2.5-4.5K). Preliminary test results indicated that the test loop had a cooling capacity of 4.2W in the 30-40K temperature range with Neon as the working fluid.

  7. Fabricating large-area metallic woodpile photonic crystals using stacking and rolling.

    PubMed

    Ibbotson, Lindsey A; Baumberg, Jeremy J

    2013-08-01

    Stacking thin polymer films supporting metal nanowire gratings provides a simple route, demonstrated here, to producing large-area metallic woodpile structures with high throughput. Under appropriate conditions the grating films can spontaneously roll up, giving a rapid and controllable method of creating multilayers. The resulting three-dimensional (3D) wire structures are flexible and potentially stretchable. Since this process can be extended to include a wide variety of functional materials, it opens up the manufacture of many tailored 3D optical metamaterials.

  8. Large-area graphene films by simple solution casting of edge-selectively functionalized graphite.

    PubMed

    Bae, Seo-Yoon; Jeon, In-Yup; Yang, Jieun; Park, Noejung; Shin, Hyeon Suk; Park, Sungjin; Ruoff, Rodney S; Dai, Liming; Baek, Jong-Beom

    2011-06-28

    We report edge-selective functionalization of graphite (EFG) for the production of large-area uniform graphene films by simply solution-casting EFG dispersions in dichloromethane on silicon oxide substrates, followed by annealing. The resultant graphene films show ambipolar transport properties with sheet resistances of 0.52-3.11 kΩ/sq at 63-90% optical transmittance. EFG allows solution processing methods for the scalable production of electrically conductive, optically transparent, and mechanically robust flexible graphene films for use in practice.

  9. Detection of Steel Fatigue Cracks with Strain Sensing Sheets Based on Large Area Electronics

    PubMed Central

    Yao, Yao; Glisic, Branko

    2015-01-01

    Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE) can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM) of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements of thin-film strain sensors, associated electronics and various control circuits deposited and integrated on a flexible polyimide substrate that can cover large areas of structures. This paper presents the development stage of a prototype strain sensing sheet based on LAE for crack detection and localization. Two types of sensing-sheet arrangements with size 6 × 6 inch (152 × 152 mm) were designed and manufactured, one with a very dense arrangement of sensors and the other with a less dense arrangement of sensors. The sensing sheets were bonded to steel plates, which had a notch on the boundary, so the fatigue cracks could be generated under cyclic loading. The sensors within the sensing sheet that were close to the notch tip successfully detected the initialization of fatigue crack and localized the damage on the plate. The sensors that were away from the crack successfully detected the propagation of fatigue cracks based on the time history of the measured strain. The results of the tests have validated the general principles of the proposed sensing sheets for crack detection and identified advantages and challenges of the two tested designs. PMID:25853407

  10. Progress on large-area polarization grating fabrication

    NASA Astrophysics Data System (ADS)

    Miskiewicz, Matthew N.; Kim, Jihwan; Li, Yanming; Komanduri, Ravi K.; Escuti, Michael J.

    2012-06-01

    Over the last several years, we have pioneered liquid crystal polarization gratings (PGs), in both switchable and polymer versions. We have also introduced their use in many applications, including mechanical/non-mechanical laser beam steering and polarization imaging/sensing. Until now, conventional holographic congurations were used to create PGs where the diameter of the active area was limited to 1-2 inches. In this paper, we discuss a new holography setup to fabricate large area PGs using spherical waves as the diverging coherent beams. Various design parameters of this setup are examined for impact on the quality of the recorded PG profile. Using this setup, we demonstrate a large area polymer PG with approximately 66 inch square area, and present detailed characterization.

  11. Optimized metallization patterns for large-area silicon solar cells

    NASA Technical Reports Server (NTRS)

    Matzen, W. T.; Chiang, S. Y.; Carbajal, B. G.

    1976-01-01

    Design criteria is presented for optimizing the front-surface metallization pattern of large-area silicon solar cells. A computer program calculates the spacing of metal fingers which minimizes resistive and shadowing losses. Finger spacing and efficiency for the optimum design are presented as a function of finger width and cell size. It is shown that quantitative evaluation of metallization pattern options can be made without cell fabrication.

  12. Uniform large-area thermionic cathode for SCALPEL

    NASA Astrophysics Data System (ADS)

    Katsap, Victor; Sewell, Peter B.; Waskiewicz, Warren K.; Zhu, Wei

    1999-11-01

    An electron beam lithography tool, which employs the SCALPEL technique, requires an extremely uniform beam to illuminate the scattering Mask, with the cathode operating in the temperature limited mode. It has been previously shown that LaB6 cathodes are not stable in this mode of operation. We have explored the possibility of implementing refined Tantalum-based emitters in the SCALPEL source cathode, and have developed large-area flat cathodes featuring suitably high emission uniformity under temperature limited operation.

  13. Chemical vapor deposition of silicon carbide for large area mirrors

    NASA Astrophysics Data System (ADS)

    Gentilman, R. L.; Maguire, E. A.

    1982-05-01

    CVD-SiC has been identified as the leading mirror material for high energy synchrotron radiation because of its high K/alpha ratio and its ability to be super-polished to less than or equal to 10 A rms roughness. Technology already exists for depositing SiC over large areas (approximately 70 cm x 20 cm). The CVD process, substrate selection, and mirror design considerations are discussed.

  14. Characterization of Large Area APDs for the EXO-200 Detector

    SciTech Connect

    Neilson, R.; LePort, F.; Pocar, A.; Kumar, K.; Odian, A.; Prescott, C.Y.; Tenev, V.; Ackerman, N.; Akimov, D.; Auger, M.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Conley, R.; Cook, S.; deVoe, R.; Dolinski, M.J.; Fairbank, W., Jr.; Farine, J.; Fierlinger, P.; Flatt, B.; /Stanford U., Phys. Dept. /Bern U., LHEP /Stanford U., Phys. Dept. /Maryland U. /Colorado State U. /Laurentian U. /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Alabama U. /SLAC /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Carleton U. /Stanford U., Phys. Dept. /Bern U., LHEP /SLAC /Laurentian U. /SLAC /Maryland U.

    2011-12-02

    EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169 K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.

  15. High Energy Astrophysics with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.

  16. Modeling a Dry Etch Process for Large-Area Devices

    SciTech Connect

    Buss, R.J.; Hebner, G.A.; Ruby, D.S.; Yang, P.

    1999-07-28

    There has been considerable interest in developing dry processes which can effectively replace wet processing in the manufacture of large area photovoltaic devices. Environmental and health issues are a driver for this activity because wet processes generally increase worker exposure to toxic and hazardous chemicals and generate large volumes of liquid hazardous waste. Our work has been directed toward improving the performance of screen-printed solar cells while using plasma processing to reduce hazardous chemical usage.

  17. Fiber-optic large area average temperature sensor

    SciTech Connect

    Looney, L.L.; Forman, P.R.

    1994-05-01

    In many instances the desired temperature measurement is only the spatial average temperature over a large area; eg. ground truth calibration for satellite imaging system, or average temperature of a farm field. By making an accurate measurement of the optical length of a long fiber-optic cable, we can determine the absolute temperature averaged over its length and hence the temperature of the material in contact with it.

  18. Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

    SciTech Connect

    Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

    2008-02-05

    The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.

  19. Research Update: Large-area deposition, coating, printing, and processing techniques for the upscaling of perovskite solar cell technology

    NASA Astrophysics Data System (ADS)

    Razza, Stefano; Castro-Hermosa, Sergio; Di Carlo, Aldo; Brown, Thomas M.

    2016-09-01

    To bring perovskite solar cells to the industrial world, performance must be maintained at the photovoltaic module scale. Here we present large-area manufacturing and processing options applicable to large-area cells and modules. Printing and coating techniques, such as blade coating, slot-die coating, spray coating, screen printing, inkjet printing, and gravure printing (as alternatives to spin coating), as well as vacuum or vapor based deposition and laser patterning techniques are being developed for an effective scale-up of the technology. The latter also enables the manufacture of solar modules on flexible substrates, an option beneficial for many applications and for roll-to-roll production.

  20. Determination of the solution-bound conformation of an amino acid binding protein by NMR paramagnetic relaxation enhancement: use of a single flexible paramagnetic probe with improved estimation of its sampling space.

    PubMed

    Bermejo, Guillermo A; Strub, Marie-Paule; Ho, Chien; Tjandra, Nico

    2009-07-15

    We demonstrate the feasibility of elucidating the bound ("closed") conformation of a periplasmic binding protein, the glutamine-binding protein (GlnBP), in solution, using paramagnetic relaxation enhancements (PREs) arising from a single paramagnetic group. GlnBP consists of two globular domains connected by a hinge. Using the ligand-free ("open") conformation as a starting point, conjoined rigid-body/torsion-angle simulated annealing calculations were performed using backbone (1)H(N)-PREs as a major source of distance information. Paramagnetic probe flexibility was accounted for via a multiple-conformer representation. A conventional approach where the entire PRE data set is enforced at once during simulated annealing yielded poor results due to inappropriate conformational sampling of the probe. On the other hand, significant improvements in coordinate accuracy were obtained by estimating the probe sampling space prior to structure calculation. Such sampling is achieved by refining the ensemble of probe conformers with intradomain PREs only, keeping the protein backbone fixed in the open form. Subsequently, while constraining the probe to the previously found conformations, the domains are allowed to move relative to each other under the influence of the non-intradomain PREs, giving the hinge region torsional degrees of freedom. Thus, by partitioning the protocol into "probe sampling" and "backbone sampling" stages, structures significantly closer to the X-ray structure of ligand-bound GlnBP were obtained.

  1. Solution-processible fabrication of large-area patterned and unpatterned gold nanostructures.

    PubMed

    Zhang, Xinping; Liu, Hongmei; Feng, Shengfei

    2009-10-21

    Solution-processible fabrication of large-area plasmonic nanostructures using colloidal gold nanoparticles has proven its advantages not only in its simplicity, low cost, high speed, and high flexibility, but also in the realization of some nanoscale optoelectronic devices that cannot be achieved by conventional methods. We demonstrate in this paper a variety of techniques for fabricating different plasmonic nanostructures using solution-processible gold nanoparticles and differently designed annealing processes. Using interference lithography and low- (<300 degrees Celsius) or high-temperature (>350 degrees Celsius) annealing processes, we succeeded in fabricating high-quality one- and two-dimensional metallic photonic crystals which exhibit promising optical responses for the exploration of new optoelectronic devices. Furthermore, using direct high-temperature (>350 degrees Celsius) annealing of a thin film of colloidal gold nanoparticles, we succeeded in fabricating large-area unpatterned isolated gold nano-island structures with a mean diameter tunable from about 35 to 100 nm and a mean height from 20 to 70 nm by controlling the concentration of the gold nanoparticle colloid, the annealing temperature, and the surface properties of the substrate. The corresponding optical response is thus tunable in the visible spectral range by changing the fabrication parameters. This introduces a new lithography-free technique for the preparation of gold nanostructures. These flexible fabrication techniques constitute a systematic route for the realization of plasmonic nanodevices.

  2. Wearable light management system for light stimulated healing of large area chronic wounds (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kallweit, David; Mayer, Jan; Fricke, Sören; Schnieper, Marc; Ferrini, Rolando

    2016-03-01

    Chronic wounds represent a significant burden to patients, health care professionals, and health care systems, affecting over 40 million patients and creating costs of approximately 40 billion € annually. We will present a medical device for photo-stimulated wound care based on a wearable large area flexible and disposable light management system consisting of a waveguide with incorporated micro- and nanometer scale optical structures for efficient light in-coupling, waveguiding and homogeneous illumination of large area wounds. The working principle of this innovative device is based on the therapeutic effects of visible light to facilitate the self-healing process of chronic wounds. On the one hand, light exposure in the red (656nm) induces growth of keratinocytes and fibroblasts in deeper layers of the skin. On the other hand, blue light (453nm) is known to have antibacterial effects predominately at the surface layers of the skin. In order to be compliant with medical requirements the system will consist of two elements: a disposable wound dressing with embedded flexible optical waveguides for the light management and illumination of the wound area, and a non-disposable compact module containing the light sources, a controller, a rechargeable battery, and a data transmission unit. In particular, we will report on the developed light management system. Finally, as a proof-of-concept, a demonstrator will be presented and its performances will be reported to demonstrate the potential of this innovative device.

  3. Development of CIGS2 Thin Films on Ultralightweight Flexible Large Area Foil Sunstrates

    NASA Technical Reports Server (NTRS)

    Dhere, Neelkanth G.; Gade, Vivek S.; Kadam, Ankur A.; Jahagirdar, Anant H.; Kulkarni, Sachin S.; Bet, Sachin M.

    2005-01-01

    The development of thin film solar cells is aimed at reducing the costs for photovoltaic systems. Use of thin film technology and thin foil substrate such as 5-mil thick stainless steel foil or 1-mil thick Ti would result in considerable costs savings. Another important aspect is manufacturing cost. Current single crystal technology for space power can cost more than $ 300 per watt at the array level and weigh more than 1 kg/sq m equivalent to specific power of approx. 65 W/kg. Thin film material such as CuIn1-xGaxS2 (CIGS2), CuIn(1-x)Ga(x)Se(2-y)S(y) (CIGSS) or amorphous hydrogenated silicon (a-Si:H) may be able to reduce both the cost and mass per unit area by an order of magnitude. Manufacturing costs for solar arrays are an important consideration for total spacecraft budget. For a medium sized 5kW satellite for example, the array manufacturing cost alone may exceed $ 2 million. Moving to thin film technology could reduce this expense to less than $ 500K. Earlier publications have demonstrated the potential of achieving higher efficiencies from CIGSS thin film solar cells on 5-mil thick stainless steel foil as well as initial stages of facility augmentation for depositing thin film solar cells on larger (6 in x 4 in) substrates. This paper presents the developmental study of achieving stress free Mo coating; uniform coatings of Mo back contact and metallic precursors. The paper also presents the development of sol gel process, refurbishment of selenization/sulfurization furnace, chemical bath deposition (CBD) for n-type CdS and scrubber for detoxification of H2S and H2Se gases.

  4. Large area photodetector based on microwave cavity perturbation techniques

    SciTech Connect

    Braggio, C. Carugno, G.; Sirugudu, R. K.; Lombardi, A.; Ruoso, G.

    2014-07-28

    We present a preliminary study to develop a large area photodetector, based on a semiconductor crystal placed inside a superconducting resonant cavity. Laser pulses are detected through a variation of the cavity impedance, as a consequence of the conductivity change in the semiconductor. A novel method, whereby the designed photodetector is simulated by finite element analysis, makes it possible to perform pulse-height spectroscopy on the reflected microwave signals. We measure an energy sensitivity of 100 fJ in the average mode without the employment of low noise electronics and suggest possible ways to further reduce the single-shot detection threshold, based on the results of the described method.

  5. Large Area Crop Inventory Experiment (LACIE). Executive summary

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The author has identified the following significant results. The Large Area Crop Inventory Experiment (LACIE), completed June 30, 1978, has met the USDA at-harvest goals (90% accuracy with a 90% confidence level) in the US Great Plains and U.S.S.R. for two consecutive years. In addition, in the U.S.S.R., LACIE indicated a shortfall in the '76-'77 wheat crop about two months prior to harvest, thus demonstrating the capability of LACIE to make accurate preharvest estimates.

  6. Method of manufacturing a large-area segmented photovoltaic module

    DOEpatents

    Lenox, Carl

    2013-11-05

    One embodiment of the invention relates to a segmented photovoltaic (PV) module which is manufactured from laminate segments. The segmented PV module includes rectangular-shaped laminate segments formed from rectangular-shaped PV laminates and further includes non-rectangular-shaped laminate segments formed from rectangular-shaped and approximately-triangular-shaped PV laminates. The laminate segments are mechanically joined and electrically interconnected to form the segmented module. Another embodiment relates to a method of manufacturing a large-area segmented photovoltaic module from laminate segments of various shapes. Other embodiments relate to processes for providing a photovoltaic array for installation at a site. Other embodiments and features are also disclosed.

  7. Laterally periodic resonator for large-area gain lasers.

    PubMed

    Feng, Yan; Ueda, Ken-Ichi

    2003-03-24

    Laterally periodic resonators, which can be constructed by use of transversely periodic phase- or amplitude-modulating elements in a cavity, are proposed for stabilization and generation of transversely coherent output from large-area gain. Lasers with periodic resonators have the combined features of conventional cavities and laser arrays. Significant low-order transverse modes and mode discrimination of a sample resonator with intracavity periodic phase elements are investigated numerically by the iteration method. Wave-propagation calculations are carried out by use of a fast Fourier transform, and a modified Prony method is used to evaluate wave functions and losses of transverse modes. Results of numerical calculations are consistent with expectations.

  8. Application issues for large-area electrochromic windows incommercial buildings

    SciTech Connect

    Lee, Eleanor S.; DiBartolomeo, D.L.

    2000-05-01

    Projections of performance from small-area devices to large-area windows and enterprise marketing have created high expectations for electrochromic glazings. As a result, this paper seeks to precipitate an objective dialog between material scientists and building-application scientists to determine whether actual large-area electrochromic devices will result in significant performance benefits and what material improvements are needed, if any, to make electrochromics more practical for commercial building applications. Few in-situ tests have been conducted with large-area electrochromic windows applied in buildings. This study presents monitored results from a full-scale field test of large-area electrochromic windows to illustrate how this technology will perform in commercial buildings. The visible transmittance (Tv) of the installed electrochromic ranged from 0.11 to 0.38. The data are limited to the winter period for a south-east-facing window. The effect of actual device performance on lighting energy use, direct sun control, discomfort glare, and interior illumination is discussed. No mechanical system loads were monitored. These data demonstrate the use of electrochromics in a moderate climate and focus on the most restrictive visual task: computer use in offices. Through this small demonstration, we were able to determine that electrochromic windows can indeed provide unmitigated transparent views and a level of dynamic illumination control never before seen in architectural glazing materials. Daily lighting energy use was 6-24 percent less compared to the 11 percent-glazing, with improved interior brightness levels. Daily lighting energy use was 3 percent less to 13 percent more compared to the 38 percent-glazing, with improved window brightness control. The electrochromic window may not be able to fulfill both energy-efficiency and visual comfort objectives when low winter direct sun is present, particularly for computer tasks using cathode-ray tube (CRT

  9. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  10. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, R.C.; Quigley, G.P.

    1996-12-17

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

  11. Large area nuclear particle detectors using ET materials

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The purpose of this SBIR Phase 1 feasibility effort was to demonstrate the usefulness of Quantex electron-trapping (ET) materials for spatial detection of nuclear particles over large areas. This demonstration entailed evaluating the prompt visible scintillation as nuclear particles impinged on films of ET materials, and subsequently detecting the nuclear particle impingement information pattern stored in the ET material, by means of the visible-wavelength luminescence produced by near-infrared interrogation. Readily useful levels of scintillation and luminescence outputs are demonstrated.

  12. Uniformity studies in large area triple-GEM based detectors

    NASA Astrophysics Data System (ADS)

    Akl, M. Abi; Bouhali, O.; Castaneda, A.; Maghrbi, Y.; Mohamed, T.

    2016-10-01

    Gas Electron Multiplier (GEM) based detectors have been used in many applications since their introduction in 1997. Large areas, e.g. exceeding 30×30 cm2, of GEM detectors are foreseen in future experiments which puts stringent requirements on the uniformity of response across the detection area. We investigate the effect of small variations of several parameters that could affect the uniformity. Parameters such as the anode pitch, the gas gap, the size and the shape of the holes are investigated. Simulation results are presented and compared to previous experimental data.

  13. LACIE large area acreage estimation. [United States of America

    NASA Technical Reports Server (NTRS)

    Chhikara, R. S.; Feiveson, A. H. (Principal Investigator)

    1979-01-01

    A sample wheat acreage for a large area is obtained by multiplying its small grains acreage estimate as computed by the classification and mensuration subsystem by the best available ratio of wheat to small grains acreages obtained from historical data. In the United States, as in other countries with detailed historical data, an additional level of aggregation was required because sample allocation was made at the substratum level. The essential features of the estimation procedure for LACIE countries are included along with procedures for estimating wheat acreage in the United States.

  14. High-Throughput Dry Processes for Large-Area Devices

    SciTech Connect

    BUSS,RICHARD J.; HEBNER,GREGORY A.; RUBY,DOUGLAS S.; YANG,PIN

    1999-11-01

    In October 1996, an interdisciplinary team began a three-year LDRD project to study the plasma processes of reactive ion etching and plasma-enhanced chemical vapor deposition on large-area silicon devices. The goal was to develop numerical models that could be used in a variety of applications for surface cleaning, selective etching, and thin-film deposition. Silicon solar cells were chosen as the experimental vehicle for this project because an innovative device design was identified that would benefit from immediate performance improvement using a combination of plasma etching and deposition processes. This report presents a summary of the technical accomplishments and conclusions of the team.

  15. Fermi Large Area Telescope Bright Gamma-ray Source List

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D.L.; Barbiellini, Guido; Bastieri, Denis; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bignami, G.F.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; /more authors..

    2009-05-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  16. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2007-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST), due to launch in November 2007, will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered pulsars. As the only presently known galactic GeV source class; pulsars will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma-ray pulsars, including millisecond pulsars, giving much better statistics for elucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric particle acceleration and radiation mechanisms, by comparing data with theoretical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all unidentified EGRET sources, to possibly uncover more radio-quiet Geminga-like pulsars.

  17. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2006-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST) will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered pulsars. As the only presently known galactic GeV source class, pulsars will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma ray pulsars, including millisecond pulsars, giving much better statistics for elucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric particle acceleration and radiation mechanisms, by comparing data with theoretical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all unidentified EGRET sources, to possibly uncover more radio-quiet Geminga-like pulsars.

  18. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2007-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST), due to launch in November 2007, will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered p ulsars. As the only presently known galactic GeV source class, pulsar s will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma-ray pulsar s, including millisecond pulsars, giving much better statistics for e lucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric partic le acceleration and radiation mechanisms, by comparing data with theo retical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all un identified EGRET sources, to possibly uncover more radio-quiet Geming a-like pulsars.

  19. Electronic hybridization of large-area stacked graphene films.

    PubMed

    Robinson, Jeremy T; Schmucker, Scott W; Diaconescu, C Bogdan; Long, James P; Culbertson, James C; Ohta, Taisuke; Friedman, Adam L; Beechem, Thomas E

    2013-01-22

    Direct, tunable coupling between individually assembled graphene layers is a next step toward designer two-dimensional (2D) crystal systems, with relevance for fundamental studies and technological applications. Here we describe the fabrication and characterization of large-area (>cm(2)), coupled bilayer graphene on SiO(2)/Si substrates. Stacking two graphene films leads to direct electronic interactions between layers, where the resulting film properties are determined by the local twist angle. Polycrystalline bilayer films have a "stained-glass window" appearance explained by the emergence of a narrow absorption band in the visible spectrum that depends on twist angle. Direct measurement of layer orientation via electron diffraction, together with Raman and optical spectroscopy, confirms the persistence of clean interfaces over large areas. Finally, we demonstrate that interlayer coupling can be reversibly turned off through chemical modification, enabling optical-based chemical detection schemes. Together, these results suggest that 2D crystals can be individually assembled to form electronically coupled systems suitable for large-scale applications.

  20. Large-Area Zone Plate Fabrication with Optical Lithography

    SciTech Connect

    Denbeaux, G.

    2011-09-09

    Zone plates as condenser optics for x-ray microscopes offer simple optical designs for both illumination and spectral resolution when used as a linear monochromator. However, due to the long write times for electron beam lithography, both the availability and the size of zone plates for condensers have been limited. Since the resolution provided by the linear monochromator scales almost linearly with the diameter of the zone plate, the full potential for zone plate monochromators as illumination systems for x-ray microscopes has not been achieved. For example, the 10-mm-diameter zone plate has demonstrated a spectral resolution of E/{Delta}E = 700[1], but with a 26-mm-diameter zone plate, the calculated spectral resolution is higher than E/{Delta}E = 3000. These large-area zone plates are possible to fabricate with the leading edge semiconductor lithography tools such as those available at the College of Nanoscale Science and Engineering at the University at Albany. One of the lithography tools available is the ASML TWINSCAN XT: 1950i with 37-nm resolution [2]. A single 300-mm wafer can contain more than 60 fields, each with a large area condenser, and the throughput of the tool can be more than one wafer every minute.

  1. Large areas elemental mapping by ion beam analysis techniques

    NASA Astrophysics Data System (ADS)

    Silva, T. F.; Rodrigues, C. L.; Curado, J. F.; Allegro, P.; Moro, M. V.; Campos, P. H. O. V.; Santos, S. B.; Kajiya, E. A. M.; Rizzutto, M. A.; Added, N.; Tabacniks, M. H.

    2015-07-01

    The external beam line of the Laboratory for Material Analysis with Ion Beams (LAMFI) is a versatile setup for multi-technique analysis. X-ray detectors for Particle Induced X-rays Emission (PIXE) measurements, a Gamma-ray detector for Particle Induced Gamma- ray Emission (PIGE), and a particle detector for scattering analysis, such as Rutherford Backscattering Spectrometry (RBS), were already installed. In this work, we present some results, using a large (60-cm range) XYZ computer controlled sample positioning system, completely developed and build in our laboratory. The XYZ stage was installed at the external beam line and its high spacial resolution (better than 5 μm over the full range) enables positioning the sample with high accuracy and high reproducibility. The combination of a sub-millimeter beam with the large range XYZ robotic stage is being used to produce elemental maps of large areas in samples like paintings, ceramics, stones, fossils, and all sort of samples. Due to its particular characteristics, this is a unique device in the sense of multi-technique analysis of large areas. With the continuous development of the external beam line at LAMFI, coupled to the robotic XYZ stage, it is becoming a robust and reliable option for regular analysis of trace elements (Z > 5) competing with the traditional in-vacuum ion-beam-analysis with the advantage of automatic rastering.

  2. Development of a Large-Area Ultracold Neutron Detector

    NASA Astrophysics Data System (ADS)

    Stoffel, Jenna; Liu, Chen-Yu; UCN Tau Collaboration

    2015-10-01

    To improve our knowledge in particle physics and cosmology, including big-bang nucleosynthesis, we need a more precise and accurate measurement of the lifetime of free neutrons. Though there have been many attempts to measure the neutron lifetime, discrepancies exist between the two major experimental techniques of the beam and the bottle methods. To resolve this discrepancy, the UCN τ experiment will trap ultracold neutrons (UCNs) to perform lifetime measurements to the 1-second level. To accomplish this goal, we are developing a large-area, high-efficiency UCN detector. We construct a scintillating UCN detector by evaporating a thin film of boron-10 onto an airbrushed layer of zinc sulfide (ZnS); the 10B-coated ZnS scintillating film is then glued to wavelength-shifting plastic, which acts as a light guide to direct photons into modern silicon photomultipliers. This new detector has similar efficiency and background noise as the previously-used ion gas detectors, but can be easily scaled up to cover large areas for many applications. The new detector opens up exciting new ways to study systematic effects, as they hold the key to the interpretation of neutron lifetime.

  3. Large-Area Zone Plate Fabrication with Optical Lithography

    NASA Astrophysics Data System (ADS)

    Denbeaux, G.

    2011-09-01

    Zone plates as condenser optics for x-ray microscopes offer simple optical designs for both illumination and spectral resolution when used as a linear monochromator. However, due to the long write times for electron beam lithography, both the availability and the size of zone plates for condensers have been limited. Since the resolution provided by the linear monochromator scales almost linearly with the diameter of the zone plate, the full potential for zone plate monochromators as illumination systems for x-ray microscopes has not been achieved. For example, the 10-mm-diameter zone plate has demonstrated a spectral resolution of E/ΔE = 700 [1], but with a 26-mm-diameter zone plate, the calculated spectral resolution is higher than E/ΔE = 3000. These large-area zone plates are possible to fabricate with the leading edge semiconductor lithography tools such as those available at the College of Nanoscale Science and Engineering at the University at Albany. One of the lithography tools available is the ASML TWINSCAN XT: 1950i with 37-nm resolution [2]. A single 300-mm wafer can contain more than 60 fields, each with a large area condenser, and the throughput of the tool can be more than one wafer every minute.

  4. Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

    NASA Astrophysics Data System (ADS)

    Lösel, Philipp; ATLAS Muon Collaboration

    2016-07-01

    Resistive strip Micromegas detectors have been tested extensively as small detectors of about 10×10 cm2 in size and they work reliably at high rates of 100 kHz/cm2 and above. Tracking resolution well below 100 μm has been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3 m2 in size. To investigate possible differences between small and large detectors, a 1 m2 detector with 2048 resistive strips at a pitch of 450 μm was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4×2.2 m2 large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6 mm×93 mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93 mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, determination of signal propagation along the 1 m long anode strips and calibration of the position of the anode strips.

  5. Piezoelectric fibers for conformal acoustics.

    PubMed

    Chocat, Noémie; Lestoquoy, Guillaume; Wang, Zheng; Rodgers, Daniel M; Joannopoulos, John D; Fink, Yoel

    2012-10-01

    Ultrasound transducers have many important applications in medical, industrial, and environmental settings. Large-active-area piezoelectric fibers are presented here, which can be woven into extended and flexible ultrasound transducing fabrics. This work opens significant opportunities for large-area, flexible and adjustable acoustic emission and sensing for a variety of emerging applications.

  6. Large-area thermoelectric high-aspect-ratio nanostructures by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Ruoho, Mikko; Juntunen, Taneli; Tittonen, Ilkka

    2016-09-01

    We report on the thermoelectric properties of large-area high-aspect-ratio nanostructures. We fabricate the structures by atomic layer deposition of conformal ZnO thin films on track-etched polycarbonate substrate. The resulting structure consists of ZnO tubules which continue through the full thickness of the substrate. The electrical and thermal properties of the structures are studied both in-plane and out-of-plane. They exhibit very low out-of-plane thermal conductivity down to 0.15 W m-1 K-1 while the in-plane sheet resistance of the films was found to be half that of the same film on glass substrate, allowing material-independent doubling of output power of any planar thin-film thermoelectric generator. The wall thickness of the fabricated nanotubes was varied within a range of up to 100 nm. The samples show polycrystalline nature with (002) preferred crystal orientation.

  7. Large-area thermoelectric high-aspect-ratio nanostructures by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Ruoho, Mikko; Juntunen, Taneli; Tittonen, Ilkka

    2016-09-01

    We report on the thermoelectric properties of large-area high-aspect-ratio nanostructures. We fabricate the structures by atomic layer deposition of conformal ZnO thin films on track-etched polycarbonate substrate. The resulting structure consists of ZnO tubules which continue through the full thickness of the substrate. The electrical and thermal properties of the structures are studied both in-plane and out-of-plane. They exhibit very low out-of-plane thermal conductivity down to 0.15 W m‑1 K‑1 while the in-plane sheet resistance of the films was found to be half that of the same film on glass substrate, allowing material-independent doubling of output power of any planar thin-film thermoelectric generator. The wall thickness of the fabricated nanotubes was varied within a range of up to 100 nm. The samples show polycrystalline nature with (002) preferred crystal orientation.

  8. Large-area thermoelectric high-aspect-ratio nanostructures by atomic layer deposition.

    PubMed

    Ruoho, Mikko; Juntunen, Taneli; Tittonen, Ilkka

    2016-09-01

    We report on the thermoelectric properties of large-area high-aspect-ratio nanostructures. We fabricate the structures by atomic layer deposition of conformal ZnO thin films on track-etched polycarbonate substrate. The resulting structure consists of ZnO tubules which continue through the full thickness of the substrate. The electrical and thermal properties of the structures are studied both in-plane and out-of-plane. They exhibit very low out-of-plane thermal conductivity down to 0.15 W m(-1) K(-1) while the in-plane sheet resistance of the films was found to be half that of the same film on glass substrate, allowing material-independent doubling of output power of any planar thin-film thermoelectric generator. The wall thickness of the fabricated nanotubes was varied within a range of up to 100 nm. The samples show polycrystalline nature with (002) preferred crystal orientation.

  9. Large area radiation source for water and wastewater treatment

    NASA Astrophysics Data System (ADS)

    Mueller, Michael T.; Lee, Seungwoo; Kloba, Anthony; Hellmer, Ronald; Kumar, Nalin; Eaton, Mark; Rambo, Charlotte; Pillai, Suresh

    2011-06-01

    There is a strong desire for processes that improve the safety of water supplies and that minimize disinfection byproducts. Stellarray is developing mercury-free next-generation x-ray and UV-C radiation sources in flat-panel and pipe form factors for water and wastewater treatment applications. These new radiation sources are designed to sterilize sludge and effluent, and to enable new treatment approaches to emerging environmental concerns such as the accumulation of estrogenic compounds in water. Our UV-C source, based on cathodoluminescent technology, differs significantly from traditional disinfection approaches using mercury arc lamps or UV LEDs. Our sources accelerate electrons across a vacuum gap, converting their energy into UV-C when striking a phosphor, or x-rays when striking a metallic anode target. Stellarray's large area radiation sources for wastewater treatment allow matching of the radiation source area to the sterilization target area for maximum coverage and improved efficiency.

  10. Large Area Crop Inventory Experiment (LACIE). Phase 1: Evaluation report

    NASA Technical Reports Server (NTRS)

    1976-01-01

    It appears that the Large Area Crop Inventory Experiment over the Great Plains, can with a reasonable expectation, be a satisfactory component of a 90/90 production estimator. The area estimator produced more accurate area estimates for the total winter wheat region than for the mixed spring and winter wheat region of the northern Great Plains. The accuracy does appear to degrade somewhat in regions of marginal agriculture where there are small fields and abundant confusion crops. However, it would appear that these regions tend also to be marginal with respect to wheat production and thus increased area estimation errors do not greatly influence the overall production estimation accuracy in the United States. The loss of segments resulting from cloud cover appears to be a random phenomenon that introduces no significant bias into the estimates. This loss does increase the variance of the estimates.

  11. Laser deposition of large-area thin films

    SciTech Connect

    Kuzanyan, A S; Petrosyan, V A; Pilosyan, S Kh; Nesterov, V M

    2011-03-31

    A new method for fabricating large-area thin films of uniform thickness on a rotating substrate is proposed. Its distinctive features are (i) the presence of a diaphragm, partially transmitting the evaporated material, between the target and substrate and (ii) the translatory motion of the rotating substrate with respect to the target at a certain velocity. The method proposed makes it possible to obtain thin films of uniform thickness on substrates with sizes limited by only the deposition chamber size. The method is experimentally verified by depositing thin CuO films on silicon substrates placed over the radius of a disk 300 mm in diameter. The deviation of the film thickness from the average value does not exceed {+-}3% throughout the entire radius, which confirms good prospects of this method for microelectronics, optical industry, and other modern technologies. (laser technology)

  12. FIRBACK: A Large Area 175 micron Survey with ISO

    NASA Astrophysics Data System (ADS)

    Lagache, Guilaine

    We have conducted a deep cosmological large area survey at 175 microns with the ISOPHOT instrument in several high latitude regions relatively free of cirrus contamination. The main, but striking, result of this survey is that number counts of sources above 100 mJy is larger by about an order of magnitude than the extrapolation of the nearby IRAS 60 microns population of infrared galaxies. Nevertheless, these counts are consistent with predictions of the source population responsible for the Cosmic Far InfraRed Background detected with COBE. The FIRBACK collaboration involves J. L. Puget, D. L. Clements, H. Dole, R. Gispert, W. T. Reach, F. R. Bouchet, C. Cesarsky, F. X. Desert, D. Elbaz, A. Franceschini, B. Guiderdoni, M. Harwit, D. Lemke, R. Laureijs and A. F. M Moorwood.

  13. Optical Distortion Evaluation in Large Area Windows using Interferometry

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Skow, Miles; Nurge, Mark A.

    2015-01-01

    It is important that imagery seen through large area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach the distortion of an acrylic window is measured using three different methods; image comparison, Moiré interferometry, and phase-shifting interferometry.

  14. A large-area gamma-ray imaging telescope system

    NASA Technical Reports Server (NTRS)

    Koch, D. G.

    1983-01-01

    The concept definition of using the External Tank (ET) of the Space Shuttle as the basis for constructing a large area gamma ray imaging telescope in space is detailed. The telescope will be used to locate and study cosmic sources of gamma rays of energy greater than 100 MeV. Both the telescope properties and the means whereby an ET is used for this purpose are described. A parallel is drawn between those systems that would be common to both a Space Station and this ET application. In addition, those systems necessary for support of the telescope can form the basis for using the ET as part of the Space Station. The major conclusions of this concept definition are that the ET is ideal for making into a gamma ray telescope, and that this telescope will provide a substantial increase in collecting area.

  15. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, Chin-Chi; Gorbatkin, Steven M.; Berry, Lee A.

    1991-01-01

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

  16. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

    1991-07-16

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

  17. Large area MEMS based ultrasound device for cancer detection

    NASA Astrophysics Data System (ADS)

    Wodnicki, Robert; Thomenius, Kai; Ming Hooi, Fong; Sinha, Sumedha P.; Carson, Paul L.; Lin, Der-Song; Zhuang, Xuefeng; Khuri-Yakub, Pierre; Woychik, Charles

    2011-08-01

    We present image results obtained using a prototype ultrasound array that demonstrates the fundamental architecture for a large area MEMS based ultrasound device for detection of breast cancer. The prototype array consists of a tiling of capacitive Micromachined Ultrasound Transducers (cMUTs) that have been flip-chip attached to a rigid organic substrate. The pitch on the cMUT elements is 185 μm and the operating frequency is nominally 9 MHz. The spatial resolution of the new probe is comparable to those of production PZT probes; however the sensitivity is reduced by conditions that should be correctable. Simulated opposed-view image registration and Speed of Sound volume reconstruction results for ultrasound in the mammographic geometry are also presented.

  18. PROSPECTS FOR GRB SCIENCE WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Band, D. L.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Battelino, M.; Bissaldi, E.; Bogaert, G.; Chiang, J.; Do Couto e Silva, E.; Cohen-Tanugi, J.; Cutini, S.; De Palma, F.; Dingus, B. L.; Fishman, G.

    2009-08-20

    The Large Area Telescope (LAT) instrument on the Fermi mission will reveal the rich spectral and temporal gamma-ray burst (GRB) phenomena in the >100 MeV band. The synergy with Fermi's Gamma-ray Burst Monitor detectors will link these observations to those in the well explored 10-1000 keV range; the addition of the >100 MeV band observations will resolve theoretical uncertainties about burst emission in both the prompt and afterglow phases. Trigger algorithms will be applied to the LAT data both onboard the spacecraft and on the ground. The sensitivity of these triggers will differ because of the available computing resources onboard and on the ground. Here we present the LAT's burst detection methodologies and the instrument's GRB capabilities.

  19. Satellite image collection modeling for large area hazard emergency response

    NASA Astrophysics Data System (ADS)

    Liu, Shufan; Hodgson, Michael E.

    2016-08-01

    Timely collection of critical hazard information is the key to intelligent and effective hazard emergency response decisions. Satellite remote sensing imagery provides an effective way to collect critical information. Natural hazards, however, often have large impact areas - larger than a single satellite scene. Additionally, the hazard impact area may be discontinuous, particularly in flooding or tornado hazard events. In this paper, a spatial optimization model is proposed to solve the large area satellite image acquisition planning problem in the context of hazard emergency response. In the model, a large hazard impact area is represented as multiple polygons and image collection priorities for different portion of impact area are addressed. The optimization problem is solved with an exact algorithm. Application results demonstrate that the proposed method can address the satellite image acquisition planning problem. A spatial decision support system supporting the optimization model was developed. Several examples of image acquisition problems are used to demonstrate the complexity of the problem and derive optimized solutions.

  20. Large area nuclear particle detectors using ET materials, phase 2

    NASA Technical Reports Server (NTRS)

    Wrigley, Charles Y.; Storti, George M.; Walter, Lee; Mathews, Scott

    1990-01-01

    This report presents work done under a Phase 2 SBIR contract for demonstrating large area detector planes utilizing Quantex electron trapping materials as a film medium for storing high-energy nuclide impingement information. The detector planes utilize energy dissipated by passage of the high-energy nuclides to produce localized populations of electrons stored in traps. Readout of the localized trapped electron populations is effected by scanning the ET plane with near-infrared, which frees the trapped electrons and results in optical emission at visible wavelengths. The effort involved both optimizing fabrication technology for the detector planes and developing a readout system capable of high spatial resolution for displaying the recorded nuclide passage tracks.

  1. Terahertz and infrared spectroscopy of gated large-area graphene.

    PubMed

    Ren, Lei; Zhang, Qi; Yao, Jun; Sun, Zhengzong; Kaneko, Ryosuke; Yan, Zheng; Nanot, Sébastien; Jin, Zhong; Kawayama, Iwao; Tonouchi, Masayoshi; Tour, James M; Kono, Junichiro

    2012-07-11

    We have fabricated a centimeter-size single-layer graphene device with a gate electrode, which can modulate the transmission of terahertz and infrared waves. Using time-domain terahertz spectroscopy and Fourier-transform infrared spectroscopy in a wide frequency range (10-10 000 cm(-1)), we measured the dynamic conductivity change induced by electrical gating and thermal annealing. Both methods were able to effectively tune the Fermi energy, E(F), which in turn modified the Drude-like intraband absorption in the terahertz as well as the "2E(F) onset" for interband absorption in the mid-infrared. These results not only provide fundamental insight into the electromagnetic response of Dirac fermions in graphene but also demonstrate the key functionalities of large-area graphene devices that are desired for components in terahertz and infrared optoelectronics. PMID:22663563

  2. Towards Large Area Growth of 3C-SiC

    SciTech Connect

    Vasiliauskas, Remigijus; Liljedahl, Rickard; Syvaejaervi, Mikael; Yakimova, Rositza

    2010-11-01

    In this work we have analyzed the possibility of upscaling the growth of 3C-SiC. The growth was done at different temperatures to find limiting mechanisms of the growth rate and to examine the morphology of grown layers. Coverage by 3C-SiC increases when increasing temperature, however more twins appeared. Activation energy of the growth is 130 kcal/mol--showing that growth rate limiting mechanism is sublimation of the source. We discuss the influence of large area 6H-SiC wafers on the formation of 3C-SiC, in which the change in basal plane orientation could also influence the growth of 3C-SiC.

  3. Direct LED backlight for large area LCD TVs: brightness analysis

    NASA Astrophysics Data System (ADS)

    Sun, Ching-Cherng; Moreno, Ivan; Chung, Shih-Hsun; Chien, Wei-Ting; Hsieh, Chih-To; Yang, Tsung-Hsun

    2007-09-01

    A direct or bottom LED backlight is a key concept in large area LCD displays because it does not use a light guide, is flat, and is easy to assemble. In this paper, a method of luminance management for a bottom LED backlight is proposed and demonstrated. We analytically calculate both the power consumption and brightness uniformity in function of: screen brightness, screen size, backlight thickness, transmittance of the LCD panel, reflective cavity efficiency, gain and cone angle of enhancement films, LED array configuration, and the average luminous flux and radiation pattern of a single LED. Moreover, a 42-inch LCD television with this backlight design approach is made and demonstrated. The bottom backlight incorporates an array of RGGB 4-in-1 multi-chip LEDs within a highly reflective box behind a diffuser and a dual brightness enhancement film. We predict with an accuracy of 94% the brightness uniformity and with 96% the luminance level.

  4. Development of large area fast microchannel plate photo-detectors

    NASA Astrophysics Data System (ADS)

    Byrum, Karen

    2011-05-01

    We report on a cross-disciplined, multi-institutional effort to develop large-scale 'frugal' photo-detectors capable of mm-scale space resolution and pico-second time resolution. This new R&D effort is being led by the High Energy Physics branch within DOE. The large-area fast photodetectors (LAPPD) being developed would have applications in many fields, including particle physics, astrophysics, nuclear sciences, and medical imaging. The basic approach uses novel inexpensive micro channel pores which have been functionalized using a technique called atomic layer deposition. A custom anode and fast electronics are used to readout the photodetector. High quantum efficiency photocathodes are also being explored. The R&D program includes detailed testing and end to end simulations.

  5. Large Area Crop Inventory Experiment (LACIE). Phase 2 evaluation report

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Documentation of the activities of the Large Area Crop Inventory Experiment during the 1976 Northern Hemisphere crop year is presented. A brief overview of the experiment is included as well as phase two area, yield, and production estimates for the United States Great Plains, Canada, and the Union of Soviet Socialist Republics spring winter wheat regions. The accuracies of these estimates are compared with independent government estimates. Accuracy assessment of the United States Great Plains yardstick region based on a through blind sight analysis is given, and reasons for variations in estimating performance are discussed. Other phase two technical activities including operations, exploratory analysis, reporting, methods of assessment, phase three and advanced system design, technical issues, and developmental activities are also included.

  6. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Lo, Nadia; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Imai, Hiroshi; Lowe, Vicki; Gibson, Steven; Brown, Courtney; Krishnan, Vasaant

    2014-04-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey is answering critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ material caught between the regimes probed by traditional tracers of the neutral ISM, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH is also detecting many new OH masers, facilitating a broad range of astrophysical studies. This proposal requests 250 hours to complete Phase 1 of the SPLASH project, which is mapping 152 square degrees in the inner Galactic Plane, including the Galactic Centre.

  7. Large area III-V infrared focal planes

    NASA Astrophysics Data System (ADS)

    Gunapala, S. D.; Ting, D. Z.; Hill, C. J.; Nguyen, J.; Soibel, A.; Rafol, S. B.; Keo, S. A.; Mumolo, J. M.; Lee, M. C.; Liu, J. K.; Yang, B.; Liao, A.

    2011-05-01

    Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for remote sensing and imaging applications. Currently, we are working on Superlattice detectors, multi-band quantum well infrared photodetectors (QWIPs), and quantum dot infrared photodetector (QDIPs) technologies suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper, we will discuss the demonstration of long-wavelength 1 K × 1 K QDIP FPA, 1 K × 1K QWIP FPA, the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP FPA, and demonstration of the first mid-wave and long-wave 1K × 1K superlattice FPA. In addition, we will discuss the advantages of III-V material system in the context of large format infrared FPAs.

  8. Pulsed-laser deposition of oxides over large areas

    NASA Astrophysics Data System (ADS)

    Greer, James A.; Van Hook, H. J.

    1991-03-01

    Due to its short wavelength and high peak power the excimer laser has become the de facto choice for Pulsed Laser Deposition (PLD) of ceramic superconductors as well as other complex chemical compounds. This paper will describe a unique excimer-based laser deposition system which is capable of producing thin films of a variety of oxide compounds or other materials over large areas (up to 46 cm2). Well over a dozen chemical compounds have been deposited with this system for a wide variety of electronic applications. Also the PLD technique has been adapted to grow thin films on the internal surface of cored cylindrical substrates in order to form resonant microwave cavity structures. The uniformity morphology and electrical properties of films grown on both planar and cylindrical substrates will be discussed.

  9. Spatially explicit shallow landslide susceptibility mapping over large areas

    USGS Publications Warehouse

    Bellugi, Dino; Dietrich, William E.; Stock, Jonathan D.; McKean, Jim; Kazian, Brian; Hargrove, Paul

    2011-01-01

    Recent advances in downscaling climate model precipitation predictions now yield spatially explicit patterns of rainfall that could be used to estimate shallow landslide susceptibility over large areas. In California, the United States Geological Survey is exploring community emergency response to the possible effects of a very large simulated storm event and to do so it has generated downscaled precipitation maps for the storm. To predict the corresponding pattern of shallow landslide susceptibility across the state, we have used the model Shalstab (a coupled steady state runoff and infinite slope stability model) which susceptibility spatially explicit estimates of relative potential instability. Such slope stability models that include the effects of subsurface runoff on potentially destabilizing pore pressure evolution require water routing and hence the definition of upslope drainage area to each potential cell. To calculate drainage area efficiently over a large area we developed a parallel framework to scale-up Shalstab and specifically introduce a new efficient parallel drainage area algorithm which produces seamless results. The single seamless shallow landslide susceptibility map for all of California was accomplished in a short run time, and indicates that much larger areas can be efficiently modelled. As landslide maps generally over predict the extent of instability for any given storm. Local empirical data on the fraction of predicted unstable cells that failed for observed rainfall intensity can be used to specify the likely extent of hazard for a given storm. This suggests that campaigns to collect local precipitation data and detailed shallow landslide location maps after major storms could be used to calibrate models and improve their use in hazard assessment for individual storms.

  10. A new approach for defect inspection on large area masks

    NASA Astrophysics Data System (ADS)

    Scheuring, Gerd; Döbereiner, Stefan; Hillmann, Frank; Falk, Günther; Brück, Hans-Jürgen

    2007-02-01

    Besides the mask market for IC manufacturing, which mainly uses 6 inch sized masks, the market for the so called large area masks is growing very rapidly. Typical applications of these masks are mainly wafer bumping for current packaging processes, color filters on TFTs, and Flip Chip manufacturing. To expose e.g. bumps and similar features on 200 mm wafers under proximity exposure conditions 9 inch masks are used, while in 300 mm wafer bumping processes (Fig. 1) 14 inch masks are handled. Flip Chip manufacturing needs masks up to 28 by 32 inch. This current maximum mask dimension is expected to hold for the next 5 years in industrial production. On the other hand shrinking feature sizes, just as in case of the IC masks, demand enhanced sensitivity of the inspection tools. A defect inspection tool for those masks is valuable for both the mask maker, who has to deliver a defect free mask to his customer, and for the mask user to supervise the mask behavior conditions during its lifetime. This is necessary because large area masks are mainly used for proximity exposures. During this process itself the mask is vulnerable by contacting the resist on top of the wafers. Therefore a regular inspection of the mask after 25, 50, or 100 exposures has to be done during its whole lifetime. Thus critical resist contamination and other defects, which lead to yield losses, can be recognized early. In the future shrinking feature dimensions will require even more sensitive and reliable defect inspection methods than they do presently. Besides the sole inspection capability the tools should also provide highly precise measurement capabilities and extended review options.

  11. Optical nano-woodpiles: large-area metallic photonic crystals and metamaterials.

    PubMed

    Ibbotson, Lindsey A; Demetriadou, Angela; Croxall, Stephen; Hess, Ortwin; Baumberg, Jeremy J

    2015-01-01

    Metallic woodpile photonic crystals and metamaterials operating across the visible spectrum are extremely difficult to construct over large areas, because of the intricate three-dimensional nanostructures and sub-50 nm features demanded. Previous routes use electron-beam lithography or direct laser writing but widespread application is restricted by their expense and low throughput. Scalable approaches including soft lithography, colloidal self-assembly, and interference holography, produce structures limited in feature size, material durability, or geometry. By multiply stacking gold nanowire flexible gratings, we demonstrate a scalable high-fidelity approach for fabricating flexible metallic woodpile photonic crystals, with features down to 10 nm produced in bulk and at low cost. Control of stacking sequence, asymmetry, and orientation elicits great control, with visible-wavelength band-gap reflections exceeding 60%, and with strong induced chirality. Such flexible and stretchable architectures can produce metamaterials with refractive index near zero, and are easily tuned across the IR and visible ranges.

  12. Optical nano-woodpiles: large-area metallic photonic crystals and metamaterials

    PubMed Central

    Ibbotson, Lindsey A.; Demetriadou, Angela; Croxall, Stephen; Hess, Ortwin; Baumberg, Jeremy J.

    2015-01-01

    Metallic woodpile photonic crystals and metamaterials operating across the visible spectrum are extremely difficult to construct over large areas, because of the intricate three-dimensional nanostructures and sub-50 nm features demanded. Previous routes use electron-beam lithography or direct laser writing but widespread application is restricted by their expense and low throughput. Scalable approaches including soft lithography, colloidal self-assembly, and interference holography, produce structures limited in feature size, material durability, or geometry. By multiply stacking gold nanowire flexible gratings, we demonstrate a scalable high-fidelity approach for fabricating flexible metallic woodpile photonic crystals, with features down to 10 nm produced in bulk and at low cost. Control of stacking sequence, asymmetry, and orientation elicits great control, with visible-wavelength band-gap reflections exceeding 60%, and with strong induced chirality. Such flexible and stretchable architectures can produce metamaterials with refractive index near zero, and are easily tuned across the IR and visible ranges. PMID:25660667

  13. Metal oxide semiconductor thin-film transistors for flexible electronics

    NASA Astrophysics Data System (ADS)

    Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard

    2016-06-01

    The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

  14. Sensing sheets based on large area electronics for fatigue crack detection

    NASA Astrophysics Data System (ADS)

    Yao, Yao; Glisic, Branko

    2015-03-01

    Reliable early-stage damage detection requires continuous structural health monitoring (SHM) over large areas of structure, and with high spatial resolution of sensors. This paper presents the development stage of prototype strain sensing sheets based on Large Area Electronics (LAE), in which thin-film strain gauges and control circuits are integrated on the flexible electronics and deposited on a polyimide sheet that can cover large areas. These sensing sheets were applied for fatigue crack detection on small-scale steel plates. Two types of sensing-sheet interconnects were designed and manufactured, and dense arrays of strain gauge sensors were assembled onto the interconnects. In total, four (two for each design type) strain sensing sheets were created and tested, which were sensitive to strain at virtually every point over the whole sensing sheet area. The sensing sheets were bonded to small-scale steel plates, which had a notch on the boundary so that fatigue cracks could be generated under cyclic loading. The fatigue tests were carried out at the Carleton Laboratory of Columbia University, and the steel plates were attached through a fixture to the loading machine that applied cyclic fatigue load. Fatigue cracks then occurred and propagated across the steel plates, leading to the failure of these test samples. The strain sensor that was close to the notch successfully detected the initialization of fatigue crack and localized the damage on the plate. The strain sensor that was away from the crack successfully detected the propagation of fatigue crack based on the time history of measured strain. Overall, the results of the fatigue tests validated general principles of the strain sensing sheets for crack detection.

  15. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays

    PubMed Central

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V.; Powell, David A.; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-01-01

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications. PMID:27000419

  16. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays.

    PubMed

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V; Powell, David A; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-03-22

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications.

  17. The role of printing techniques for large-area dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Mariani, Paolo; Vesce, Luigi; Di Carlo, Aldo

    2015-10-01

    The versatility of printing technologies and their intrinsic ability to outperform other techniques in large-area deposition gives scope to revolutionize the photovoltaic (PV) manufacturing field. Printing methods are commonly used in conventional silicon-based PVs to cover part of the production process. Screen printing techniques, for example, are applied to deposit electrical contacts on the silicon wafer. However, it is with the advent of third generation PVs that printing/coating techniques have been extensively used in almost all of the manufacturing processes. Among all the third generation PVs, dye sensitized solar cell (DSSC) technology has been developed up to commercialization levels. DSSCs and modules can be fabricated by adopting all of the main printing techniques on both rigid and flexible substrates. This allows an easy tuning of cell/module characteristics to the desired application. Transparency, colour, shape, layout and other DSSC’s features can be easily varied by changing the printing parameters and paste/ink formulations used in the printing process. This review focuses on large-area printing/coating technologies for the fabrication of DSSCs devices. The most used and promising techniques are presented underlining the process parameters and applications.

  18. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays

    NASA Astrophysics Data System (ADS)

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V.; Powell, David A.; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-03-01

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications.

  19. A Large Area Tactile Sensor Patch Based on Commercial Force Sensors

    PubMed Central

    Vidal-Verdú, Fernando; Barquero, Maria Jose; Castellanos-Ramos, Julián; Navas-González, Rafael; Sánchez, Jose Antonio; Serón, Javier; García-Cerezo, Alfonso

    2011-01-01

    This paper reports the design of a tactile sensor patch to cover large areas of robots and machines that interact with human beings. Many devices have been proposed to meet such a demand. These realizations are mostly custom-built or developed in the lab. The sensor of this paper is implemented with commercial force sensors. This has the benefit of a more foreseeable response of the sensor if its behavior is understood as the aggregation of readings from all the individual force sensors in the array. A few reported large area tactile sensors are also based on commercial sensors. However, the one in this paper is the first of this kind based on the use of polymeric commercial force sensing resistors (FSR) as unit elements of the array or tactels, which results in a robust sensor. The paper discusses design issues related to some necessary modifications of the force sensor, its assembly in an array, and the signal conditioning. The patch has 16 × 9 force sensors mounted on a flexible printed circuit board with a spatial resolution of 18.5 mm. The force range of a tactel is 6 N and its sensitivity is 0.6 V/N. The array is read at a rate of 78 frames per second. Finally, two simple application examples are also carried out with the sensor mounted on the forearm of a rescue robot that communicates with the sensor through a CAN bus. PMID:22163910

  20. Investigation of welded interconnection of large area wraparound contacted silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lott, D. R.

    1984-01-01

    An investigation was conducted to evaluate the welding and temperature cycle testing of large area 5.9 x 5.9 wraparound silicon solar cells utilizing printed circuit substrates with SSC-155 interconnect copper metals and the LMSC Infrared Controlled weld station. An initial group of 5 welded modules containing Phase 2 developmental 5.9 x 5.9 cm cells were subjected to cyclical temperatures of + or 80 C at a rate of 120 cycles per day. Anomalies were noted in the adhesion of the cell contact metallization; therefore, 5 additional modules were fabricated and tested using available Phase I cells with demonstrated contact integrity. Cycling of the later module type through 12,000 cycles indicated the viability of this type of lightweight flexible array concept. This project demonstrated acceptable use of an alternate interconnect copper in combination with large area wraparound cells and emphasized the necessity to implement weld pull as opposed to solder pull procedures at the cell vendors for cells that will be interconnected by welding.

  1. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays.

    PubMed

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V; Powell, David A; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-01-01

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications. PMID:27000419

  2. Total-internal-reflection-based photomask for large-area photolithography

    NASA Astrophysics Data System (ADS)

    Hung, Shao-Kang; Lin, Kung-Hsuan; Chen, Cheng-Lung; Chou, Chen-Hsun; Lin, You-Chuan

    2016-05-01

    Photolithography has been widely implemented with a photomask in contact or in close proximity to the photoresist layer. The flatness of the substrates is a crucial factor to guarantee the quality of the entire patterned photoresist (PR) layer especially for large-area photolithography. However, some substrates, such as sapphire wafers, do not possess highly uniform thickness as silicon wafer does. In this work, we demonstrate that a flexible polydimethylsiloxane (PDMS) photomask with optical total-internal-reflection structure can effectively circumvent this problem for mass production. Different from conventional photomask that the light is blocked by the patterned reflective/absorbing materials, the distributions of light intensity on the PR is engineered by the geometric structure of the transparent PDMS photomask. We demonstrate that 4 in. patterned sapphire wafers can be successfully fabricated by using this PDMS photomask, which can be easily integrated into the present techniques in industry for mass production of substrates for GaN-based optoelectronic devices.

  3. The Trigger And Onboard Filter of the GLAST Large Area Telescope

    SciTech Connect

    Hughes, R.; Grove, J.E.; Kocian, M.; Ritz, S.; Russell, J.J.; Siskind, E.; Smith, P.; Winer, B.; Usher, T.; /SLAC

    2007-11-13

    The GLAST Large Area Telescope (LAT) will measure the cosmic gamma-ray flux in the energy range 20 MeV to >300 GeV. The LAT will open a new and important window on a wide variety of high-energy phenomena. Achieving this capability requires a hardware trigger and onboard software event filters that are robust and highly efficient for gamma rays while keeping the event rates due to the much larger fluxes of charged particle backgrounds at an acceptable level. Because of the important discovery windows for science and the uncertainties in the background fluxes, configuration flexibility is a particularly important system feature. This poster describes the purposes and architecture of the system, the components and capabilities of the hardware trigger and onboard software filters, testing and operation experience on the ground, and the on-orbit operations plan and expected performance.

  4. The Trigger and Onboard Filter of the GLAST Large Area Telescope

    SciTech Connect

    Hughes, R.; Grove, J. E.; Kocian, M.; Ritz, S.; Russell, J. J.; Siskind, E.; Smith, P.; Usher, T.; Winer, B.

    2007-07-12

    The GLAST Large Area Telescope (LAT) will measure the cosmic gamma-ray flux in the energy range 20 MeV to >300 GeV. The LAT will open a new and important window on a wide variety of high-energy phenomena. Achieving the capability requires a hardware trigger and onboard software event filters that are robust and highly efficient for gamma rays while remaining powerful rejecters of the much larger fluxes of charged-particle backgrounds. Because of the important discovery windows for science and the uncertainties in the background fluxes, configuration flexibility is a particularly important system feature. This paper describes the purposes and architecture of the system, the components and capabilities of the hardware trigger and onboard software filters, and the on-orbit operations plan and expected performance.

  5. Magnetic Carpet Probe for Large Area Instant Crack/Corrosion Detection and Health Monitoring

    SciTech Connect

    Sun Yushi; Ouyang Tianhe; Yang Xinle; Zhu Haiou

    2007-03-21

    Recently a new NDE tool, Magnet Carpet Probe (MCP), has been developed by Innovative Materials Testing Technologies, Inc. supported by FAA to meet the demands of large area crack/corrosion detection and health monitoring. MCP is a two-dimensional coil array built on a piece of very thin flexible printed circuit board. A two-dimensional electromagnetic scan is going on within the MCP placed on top of a metallic surface under inspection. Therefore, one can finish the inspection, without moving anything, and see the crack/corrosion identification image on the instrument screen in a few second. Recent test results show that it can detect 0.030 x 0.016'' EDM notches on a Titanium standard; 0.024'' {approx} 0.036: real cracks on titanium standards, as well as penetrate through a 0.040'' aluminum layer for corrosion detection.

  6. Large area ceramic thin films on plastics: A versatile route via solution processing

    SciTech Connect

    Kozuka, H.; Yamano, A.; Uchiyama, H.; Takahashi, M.; Fukui, T.; Yoki, M.; Akase, T.

    2012-01-01

    A new general route for large area, submicron thick ceramic thin films (crystalline metal oxide thin films) on plastic substrates is presented, where the crystallization of films is guaranteed by a firing process. Gel films are deposited on silicon substrates with a release layer and fired to be ceramic films, followed by transferring onto plastic substrates using adhesives. The ceramic films thus fabricated on plastics exhibit a certain degree of flexibility, implying the possibility of the technique to be applied to high-throughput roll-to-roll processes. Using this technique, we successfully realized transparent anatase thin films that provide high optical reflectance and transparent indium tin oxide thin films that exhibit electrical conductivity on polycarbonate and acrylic resin substrates, respectively. Crystallographically oriented zinc oxide films and patterned zinc oxide films are also demonstrated to be realized on acrylic resin substrates.

  7. Building ISOC Status Displays for the Large AreaTelescope aboard the Gamma Ray Large Area Space Telescope (GLAST) Observatory

    SciTech Connect

    Ketchum, Christina; /SLAC

    2006-09-01

    In September 2007 the Gamma Ray Large Area Space Telescope (GLAST) is scheduled to launch aboard a Delta II rocket in order to put two high-energy gamma-ray detectors, the Large Area Telescope (LAT) and the GLAST Burst Monitor (GBM) into low earth orbit. The Instrument Science Operations Center (ISOC) at SLAC is responsible for the LAT operations for the duration of the mission, and will therefore build an operations center including a monitoring station at SLAC to inform operations staff and visitors of the status of the LAT instrument and GLAST. This monitoring station is to include sky maps showing the location of GLAST in its orbit as well as the LAT's projected field of view on the sky containing known gamma-ray sources. The display also requires a world map showing the locations of GLAST and three Tracking and Data Relay Satellites (TDRS) relative to the ground, their trail lines, and ''footprint'' circles indicating the range of communications for each satellite. The final display will also include a space view showing the orbiting and pointing information of GLAST and the TDRS satellites. In order to build the displays the astronomy programs Xephem, DS9, SatTrack, and STK were employed to model the position of GLAST and pointing information of the LAT instrument, and the programming utilities Python and Cron were used in Unix to obtain updated information from database and load them into the programs at regular intervals. Through these methods the indicated displays were created and combined to produce a monitoring display for the LAT and GLAST.

  8. TFT-Based Active Pixel Sensors for Large Area Thermal Neutron Detection

    NASA Astrophysics Data System (ADS)

    Kunnen, George

    Due to diminishing availability of 3He, which is the critical component of neutron detecting proportional counters, large area flexible arrays are being considered as a potential replacement for neutron detection. A large area flexible array, utilizing semiconductors for both charged particle detection and pixel readout, ensures a large detection surface area in a light weight rugged form. Such a neutron detector could be suitable for deployment at ports of entry. The specific approach used in this research, uses a neutron converter layer which captures incident thermal neutrons, and then emits ionizing charged particles. These ionizing particles cause electron-hole pair generation within a single pixel's integrated sensing diode. The resulting charge is then amplified via a low-noise amplifier. This document begins by discussing the current state of the art in neutron detection and the associated challenges. Then, for the purpose of resolving some of these issues, recent design and modeling efforts towards developing an improved neutron detection system are described. Also presented is a low-noise active pixel sensor (APS) design capable of being implemented in low temperature indium gallium zinc oxide (InGaZnO) or amorphous silicon (a-Si:H) thin film transistor process compatible with plastic substrates. The low gain and limited scalability of this design are improved upon by implementing a new multi-stage self-resetting APS. For each APS design, successful radiation measurements are also presented using PiN diodes for charged particle detection. Next, detection array readout methodologies are modeled and analyzed, and use of a matched filter readout circuit is described as well. Finally, this document discusses detection diode integration with the designed TFT-based APSs.

  9. Fermi Large Area Telescope Operations: Progress Over 4 Years

    SciTech Connect

    Cameron, Robert A.; /SLAC

    2012-06-28

    The Fermi Gamma-ray Space Telescope was launched into orbit in June 2008, and is conducting a multi-year gamma-ray all-sky survey, using the main instrument on Fermi, the Large Area Telescope (LAT). Fermi began its science mission in August 2008, and has now been operating for almost 4 years. The SLAC National Accelerator Laboratory hosts the LAT Instrument Science Operations Center (ISOC), which supports the operation of the LAT in conjunction with the Mission Operations Center (MOC) and the Fermi Science Support Center (FSSC), both at NASA's Goddard Space Flight Center. The LAT has a continuous output data rate of about 1.5 Mbits per second, and data from the LAT are stored on Fermi and transmitted to the ground through TDRS and the MOC to the ISOC about 10 times per day. Several hundred computers at SLAC are used to process LAT data to perform event reconstruction, and gamma-ray photon data are subsequently delivered to the FSSC for public release with a few hours of being detected by the LAT. We summarize the current status of the LAT, and the evolution of the data processing and monitoring performed by the ISOC during the first 4 years of the Fermi mission, together with future plans for further changes to detected event data processing and instrument operations and monitoring.

  10. Dark Matter Searches with the Fermi Large Area Telescope

    SciTech Connect

    Meurer, Christine

    2008-12-24

    The Fermi Gamma-Ray Space Telescope, successfully launched on June 11th, 2008, is the next generation satellite experiment for high-energy gamma-ray astronomy. The main instrument, the Fermi Large Area Telescope (LAT), with a wide field of view (>2 sr), a large effective area (>8000 cm{sup 2} at 1 GeV), sub-arcminute source localization, a large energy range (20 MeV-300 GeV) and a good energy resolution (close to 8% at 1 GeV), has excellent potential to either discover or to constrain a Dark Matter signal. The Fermi LAT team pursues complementary searches for signatures of particle Dark Matter in different search regions such as the galactic center, galactic satellites and subhalos, the milky way halo, extragalactic regions as well as the search for spectral lines. In these proceedings we examine the potential of the LAT to detect gamma-rays coming from Weakly Interacting Massive Particle annihilations in these regions with special focus on the galactic center region.

  11. Influence of the Earth's magnetic field on large area photomultipliers

    SciTech Connect

    Leonora, E.; Aiello, S.; Leotta, G.

    2011-07-01

    The influence of the Earth's magnetic field on large area photomultipliers proposed for a future deep sea neutrino telescope was studied under the EU-funded KM3NeT design study. The aims were to evaluate variations in PMT performance in the Earth's magnetic field and to decide whether the use of magnetic shielding is necessary. Measurements were performed on three Hamamatsu PMTs: two 8-inch R5912 types, one of these with super-bi-alkali photocathode, and a 10-inch R7081 type with a standard bi-alkali photocathode. The various characteristics of the PMTs were measured while varying the PMT orientations with respect to the Earth's magnetic field, both with and without a mu-metal cage as magnetic shield. In the 8-inch PMTs the impact of the magnetic field was found to be smaller than that on the 10-inch PMT. The increased quantum efficiency in the 8 super-bi-alkali PMT almost compensated its smaller detection surface compared to the 10' PMT. No significant effects were measured upon transit time and the fraction of spurious pulses. (authors)

  12. Large Area Nondestructive Evaluation of a Fatigue Loaded Composite Structure

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Burke, Eric R.; Horne, Michael R.; Madaras, Eric I.

    2016-01-01

    Large area nondestructive evaluation (NDE) inspections are required for fatigue testing of composite structures to track damage initiation and growth. Of particular interest is the progression of damage leading to ultimate failure to validate damage progression models. In this work, passive thermography and acoustic emission NDE were used to track damage growth up to failure of a composite three-stringer panel. Fourteen acoustic emission sensors were placed on the composite panel. The signals from the array were acquired simultaneously and allowed for acoustic emission location. In addition, real time thermal data of the composite structure were acquired during loading. Details are presented on the mapping of the acoustic emission locations directly onto the thermal imagery to confirm areas of damage growth leading to ultimate failure. This required synchronizing the acoustic emission and thermal data with the applied loading. In addition, processing of the thermal imagery which included contrast enhancement, removal of optical barrel distortion and correction of angular rotation before mapping the acoustic event locations are discussed.

  13. FERMI LARGE AREA TELESCOPE DETECTION OF SUPERNOVA REMNANT RCW 86

    SciTech Connect

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-20

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ∼5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ∼ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  14. Saturn: A large area x-ray simulation accelerator

    SciTech Connect

    Bloomquist, D.D.; Stinnett, R.W.; McDaniel, D.H.; Lee, J.R.; Sharpe, A.W.; Halbleib, J.A.; Schlitt, L.G.; Spence, P.W.; Corcoran, P.

    1987-01-01

    Saturn is the result of a major metamorphosis of the Particle Beam Fusion Accelerator-I (PBFA-I) from an ICF research facility to the large-area x-ray source of the Simulation Technology Laboratory (STL) project. Renamed Saturn, for its unique multiple-ring diode design, the facility is designed to take advantage of the numerous advances in pulsed power technology made by the ICF program in recent years and much of the existing PBFA-I support system. Saturn will include significant upgrades in the energy storage and pulse-forming sections. The 36 magnetically insulated transmission lines (MITLs) that provided power flow to the ion diode of PBFA-I were replaced by a system of vertical triplate water transmission lines. These lines are connected to three horizontal triplate disks in a water convolute section. Power will flow through an insulator stack into radial MITLs that drive the three-ring diode. Saturn is designed to operate with a maximum of 750 kJ coupled to the three-ring e-beam diode with a peak power of 25 TW to provide an x-ray exposure capability of 5 x 10/sup 12/ rads/s (Si) and 5 cal/g (Au) over 500 cm/sup 2/.

  15. Large-area nanogap plasmon resonator arrays for plasmonics applications

    NASA Astrophysics Data System (ADS)

    Jin, Mingliang; van Wolferen, Henk; Wormeester, Herbert; van den Berg, Albert; Carlen, Edwin T.

    2012-07-01

    Large-area (~8000 mm2) Au nanogap plasmon resonator array substrates manufactured using maskless laser interference lithography (LIL) with high uniformity are presented. The periodically spaced subwavelength nanogap arrays are formed between adjacent nanopyramid (NPy) structures with precisely defined pitch and high length density (~1 km cm-2), and are ideally suited as scattering sites for surface enhanced Raman scattering (SERS), as well as refractive index sensing. The two-dimensional grid arrangement of NPy structures renders the excitation of the plasmon resonators minimally dependent on the incident polarization. The SERS average enhancement factor (AEF) has been characterized using over 30 000 individual measurements of benzenethiol (BT) chemisorbed on the Au NPy surfaces. From the 1(a1), βCCC + νCS ring mode (1074 cm-1) of BT on surfaces with pitch λg = 200 nm, AEF = 0.8 × 106 and for surfaces with λg = 500 nm, AEF = 0.3 × 107 from over 99% of the imaged spots. Maximum AEFs > 108 have been measured in both cases.

  16. An advanced open path atmospheric pollution monitor for large areas

    SciTech Connect

    Taylor, L.; Suhre, D.; Mani, S.

    1996-12-31

    Over 100 million gallons of radioactive and toxic waste materials generated in weapon materials production are stored in 322 tanks buried within large areas at DOE sites. Toxic vapors occur in the tank headspace due to the solvents used and chemical reactions within the tanks. To prevent flammable or explosive concentration of volatile vapors, the headspace are vented, either manually or automatically, to the atmosphere when the headspace pressure exceeds preset values. Furthermore, 67 of the 177 tanks at the DOE Hanford Site are suspected or are known to be leaking into the ground. These underground storage tanks are grouped into tank farms which contain closely spaced tanks in areas as large as 1 km{sup 2}. The objective of this program is to protect DOE personnel and the public by monitoring the air above these tank farms for toxic air pollutants without the monitor entering the tanks farms, which can be radioactive. A secondary objective is to protect personnel by monitoring the air above buried 50 gallon drums containing moderately low radioactive materials but which could also emit toxic air pollutants.

  17. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Atwood, W. B.; Bagagli, R.; Baldini, L.; Bellardi, F.; Bellazzini, R.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bisello, D.; Baughman, B. M. E-mail: massimiliano.razzano@pi.infn.it

    2009-05-10

    The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new {gamma}-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E {>=} 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of {gamma} = 1.51{sup +0.05} {sub -0.04} with an exponential cutoff at E{sub c} = 2.9 {+-} 0.1 GeV. Spectral fits with generalized cutoffs of the form e{sup -(E/E{sub c}){sup b}} require b {<=} 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.

  18. Pulsar Simulations for the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Razzano, M.; Harding, A. K.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Burnett, T.; Chiang, J.; Digel, S. W.; Dubois, R.; Kuss, M. W.; Latronico, L.; McEnery, J. E.; Omodei, N.; Pesce-Rollins, M.; Sgro, C.; Spandre, G.; Thompson, D. J.

    2009-01-01

    Pulsars are among the prime targets for the Large Area Telescope (LAT) aboard the recently launched Fermi observatory. The LAT will study the gamma-ray Universe between 20 MeV and 300 GeV with unprecedented detail. Increasing numbers of gamma-ray pulsars are being firmly identified, yet their emission mechanisms are far from being understood. To better investigate and exploit the tAT capabilities for pulsar science. a set of new detailed pulsar simulation tools have been developed within the LAT collaboration. The structure of the pulsar simulator package (PulsarSpeccrum) is presented here. Starting from photon distributions in energy and phase obtained from theoretical calculations or phenomenological considerations, gamma-rays are generated and their arrival times at the spacecraft are determined by taking Into account effects such as barycentric effects and timing noise. Pulsars in binary systems also can be simulated given orbital parameters. We present how simulations can be used for generating a realistic set of gamma rays as observed by the LAT, focusing on some case studies that show the performance of the LAT for pulsar observations.

  19. Fermi Large Area Telescope Detection of Supernova Remnant RCW 86

    NASA Astrophysics Data System (ADS)

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-01

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ~5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ~ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  20. DESIGN OF A LARGE-AREA FAST NEUTRON DIRECTIONAL DETECTOR.

    SciTech Connect

    VANIER, P.E.

    2006-10-29

    A large-area fast-neutron double-scatter directional detector and spectrometer is being constructed using l-meter-long plastic scintillator paddles with photomultiplier tubes at both ends. The scintillators detect fast neutrons by proton recoil and also gamma rays by Compton scattering. The paddles are arranged in two parallel planes so that neutrons can be distinguished from muons and gamma rays by time of flight between the planes. The signal pulses are digitized with a time resolution of one gigasample per second. The location of an event along each paddle can be determined from the relative amplitudes or timing of the signals at the ends. The angle of deflection of a neutron in the first plane can be estimated from the energy deposited by the recoil proton, combined with the scattered neutron time-of-flight energy. Each scattering angle can be back-projected as a cone, and many intersecting cones define the incident neutron direction from a distant point source. Moreover, the total energy of each neutron can be obtained, allowing some regions of a fission source spectrum to be distinguished from background generated by cosmic rays. Monte Carlo calculations will be compared with measurements.

  1. Ultra-stiff large-area carpets of carbon nanotubes.

    PubMed

    Meysami, Seyyed Shayan; Dallas, Panagiotis; Britton, Jude; Lozano, Juan G; Murdock, Adrian T; Ferraro, Claudio; Gutierrez, Eduardo Saiz; Rijnveld, Niek; Holdway, Philip; Porfyrakis, Kyriakos; Grobert, Nicole

    2016-06-01

    Herewith, we report the influence of post-synthesis heat treatment (≤2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm(2)) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, ≥4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes. PMID:27240959

  2. Development of a large area space solar cell assembly

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.

    1982-01-01

    The development of a large area high efficiency solar cell assembly is described. The assembly consists of an ion implanted silicon solar cell and glass cover. The important attributes of fabrication are the use of a back surface field which is compatible with a back surface reflector, and integration of coverglass application and cell fabrications. Cell development experiments concerned optimization of ion implantation processing of 2 ohm-cm boron-doped silicon. Process parameters were selected based on these experiments and cells with area of 34.3 sq cm wre fabricated. The average AMO efficiency of the twenty-five best cells was 13.9% and the best bell had an efficiency of 14.4%. An important innovation in cell encapsulation was also developed. In this technique, the coverglass is applied before the cell is sawed to final size. The coverglass and cell are then sawed as a unit. In this way, the cost of the coverglass is reduced, since the tolerance on glass size is relaxed, and costly coverglass/cell alignment procedures are eliminated. Adhesive investigated were EVA, FEP-Teflon sheet and DC 93-500. Details of processing and results are reported.

  3. Edge field emission of large-area single layer graphene

    NASA Astrophysics Data System (ADS)

    Kleshch, Victor I.; Bandurin, Denis A.; Orekhov, Anton S.; Purcell, Stephen T.; Obraztsov, Alexander N.

    2015-12-01

    Field electron emission from the edges of large-area (∼1 cm × 1 cm) graphene films deposited onto quartz wafers was studied. The graphene was previously grown by chemical vapour deposition on copper. An extreme enhancement of electrostatic field at the edge of the films with macroscopically large lateral dimensions and with single atom thickness was achieved. This resulted in the creation of a blade type electron emitter, providing stable field emission at low-voltage with linear current density up to 0.5 mA/cm. A strong hysteresis in current-voltage characteristics and a step-like increase of the emission current during voltage ramp up were observed. These effects were explained by the local mechanical peeling of the graphene edge from the quartz substrate by the ponderomotive force during the field emission process. Specific field emission phenomena exhibited in the experimental study are explained by a unique combination of structural, electronic and mechanical properties of graphene. Various potential applications ranging from linear electron beam sources to microelectromechanical systems are discussed.

  4. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Lo, Nadia; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Imai, Hiroshi; Lowe, Vicki; Gibson, Steven; Jones, Courtney; Krishnan, Vasaant

    2013-10-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey will answer critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ material caught between the regimes probed by traditional tracers of the neutral ISM, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH will also detect many new OH masers, facilitating a broad range of astrophysical studies. This proposal requests 670 hours spread over two semesters to complete Phase 1 of the SPLASH project, which will map 152 square degrees in the inner Galactic Plane, including the Galactic Centre. Following the ongoing success of the project, we request that its pre-graded status be renewed for a final two semesters.

  5. Saturn: A large area X-ray simulation accelerator

    NASA Astrophysics Data System (ADS)

    Bloomquist, D. D.; Stinnett, R. W.; McDaniel, D. H.; Lee, J. R.; Sharpe, A. W.; Halbleib, J. A.; Schlitt, L. G.; Spence, P. W.; Corcoran, P.

    1987-06-01

    Saturn is the result of a major metamorphosis of the Particle Beam Fusion Accelerator-I (PBFA-I) from an ICF research facility to the large-area X-ray source of the Simulation Technology Laboratory (STL) project. Renamed Saturn, for its unique multiple-ring diode design, the facility is designed to take advantage of the numerous advances in pulsed power technology. Saturn will include significant upgrades in the energy storage and pulse-forming sections. The 36 magnetically insulated transmission lines (MITLs) that provided power flow to the ion diode of PBFA-I were replaced by a system of vertical triplate water transmission lines. These lines are connected to three horizontal triplate disks in a water convolute section. Power will flow through an insulator stack into radial MITLs that drive the three-ring diode. Saturn is designed to operate with a maximum of 750 kJ coupled to the three-ring e-beam diode with a peak power of 25 TW to provide an X-ray exposure capability of 5 x 10 rads/s (Si) and 5 cal/g (Au) over 500 cm.

  6. Research and Development of Large Area Color AC Plasma Displays

    NASA Astrophysics Data System (ADS)

    Shinoda, Tsutae

    1998-10-01

    Plasma display is essentially a gas discharge device using discharges in small cavities about 0. 1 m. The color plasma displays utilize the visible light from phosphors excited by the ultra-violet by discharge in contrast to monochrome plasma displays utilizing visible light directly from gas discharges. At the early stage of the color plasma display development, the degradation of the phosphors and unstable operating voltage prevented to realize a practical color plasma display. The introduction of the three-electrode surface-discharge technology opened the way to solve the problems. Two key technologies of a simple panel structure with a stripe rib and phosphor alignment and a full color image driving method with an address-and-display-period-separated sub-field method have realized practically available full color plasma displays. A full color plasma display has been firstly developed in 1992 with a 21-in.-diagonal PDP and then a 42-in.-diagonal PDP in 1995 Currently a 50-in.-diagonal color plasma display has been developed. The large area color plasma displays have already been put into the market and are creating new markets, such as a wall hanging TV and multimedia displays for advertisement, information, etc. This paper will show the history of the surface-discharge color plasma display technologies and current status of the color plasma display.

  7. Large area patterning using interference and nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Bläsi, B.; Tucher, N.; Höhn, O.; Kübler, V.; Kroyer, T.; Wellens, Ch.; Hauser, H.

    2016-04-01

    Interference lithography (IL) is the best suited technology for the origination of large area master structures with high resolution. In prior works, we seamlessly pattern areas of up to 1.2 x 1.2 m2 with periodic features, i.e. a diffraction grating with a period in the micron range. For this process we use an argon ion laser emitting at 363.8 nm. Thus, feasible periods are in the range of 100 μm to 200 nm. Edge-defined techniques or also called (self-aligned) double patterning processes can be used to double the spatial frequency of such structures. This way, we aim to reduce achievable periods further down to 100 nm. In order to replicate master structures, we make use of nanoimprint lithography (NIL) processes. In this work, we present results using IL as mastering and NIL as replication technology in the fields of photovoltaics as well as display and lighting applications. In photovoltaics different concepts like the micron-scale patterning of the front side as well as the realization of rear side diffraction gratings are presented. The benefit for each is shown on final device level. In the context of display and lighting applications, we realized various structures ranging from designed, symmetric or asymmetric, diffusers, antireflective and/or antiglare structures, polarization optical elements (wire grid polarizers), light guidance and light outcoupling structures.

  8. Exploring the conformational energy landscape of glassy disaccharides by cross polarization magic angle spinning 13C nuclear magnetic resonance and numerical simulations. II. Enhanced molecular flexibility in amorphous trehalose.

    PubMed

    Lefort, Ronan; Bordat, Patrice; Cesaro, Attilio; Descamps, Marc

    2007-01-01

    This paper uses chemical shift surfaces to simulate experimental (13)C cross polarization magic angle spinning spectra for amorphous solid state disaccharides, paying particular attention to the glycosidic linkage atoms in trehalose, sucrose, and lactose. The combination of molecular mechanics with density functional theory/gauge invariant atomic orbital ab initio methods provides reliable structural information on the conformational distribution in the glass. The results are interpreted in terms of an enhanced flexibility that trehalose possesses in the amorphous solid state, at least on the time scale of (13)C nuclear magnetic resonance measurements. Implications of these findings for the fragility of trehalose glass and bioprotectant action are discussed. PMID:17212504

  9. Exploring the conformational energy landscape of glassy disaccharides by cross polarization magic angle spinning 13C nuclear magnetic resonance and numerical simulations. II. Enhanced molecular flexibility in amorphous trehalose

    NASA Astrophysics Data System (ADS)

    Lefort, Ronan; Bordat, Patrice; Cesaro, Attilio; Descamps, Marc

    2007-01-01

    This paper uses chemical shift surfaces to simulate experimental C13 cross polarization magic angle spinning spectra for amorphous solid state disaccharides, paying particular attention to the glycosidic linkage atoms in trehalose, sucrose, and lactose. The combination of molecular mechanics with density functional theory/gauge invariant atomic orbital ab initio methods provides reliable structural information on the conformational distribution in the glass. The results are interpreted in terms of an enhanced flexibility that trehalose possesses in the amorphous solid state, at least on the time scale of C13 nuclear magnetic resonance measurements. Implications of these findings for the fragility of trehalose glass and bioprotectant action are discussed.

  10. Conformational Flexibility of a Short Loop near the Active Site of the SARS-3CLpro is Essential to Maintain Catalytic Activity

    NASA Astrophysics Data System (ADS)

    Li, Chunmei; Teng, Xin; Qi, Yifei; Tang, Bo; Shi, Hailing; Ma, Xiaomin; Lai, Luhua

    2016-02-01

    The SARS 3C-like proteinase (SARS-3CLpro), which is the main proteinase of the SARS coronavirus, is essential to the virus life cycle. This enzyme has been shown to be active as a dimer in which only one protomer is active. However, it remains unknown how the dimer structure maintains an active monomer conformation. It has been observed that the Ser139-Leu141 loop forms a short 310-helix that disrupts the catalytic machinery in the inactive monomer structure. We have tried to disrupt this helical conformation by mutating L141 to T in the stable inactive monomer G11A/R298A/Q299A. The resulting tetra-mutant G11A/L141T/R298A/Q299A is indeed enzymatically active as a monomer. Molecular dynamics simulations revealed that the L141T mutation disrupts the 310-helix and helps to stabilize the active conformation. The coil-310-helix conformational transition of the Ser139-Leu141 loop serves as an enzyme activity switch. Our study therefore indicates that the dimer structure can stabilize the active conformation but is not a required structure in the evolution of the active enzyme, which can also arise through simple mutations.

  11. Progress on conformal microwave array applicators for heating chestwall disease

    NASA Astrophysics Data System (ADS)

    Stauffer, P. R.; Maccarini, P. F.; Juang, T.; Jacobsen, S. K.; Gaeta, C. J.; Schlorff, J. L.; Milligan, A. J.

    2007-02-01

    Previous studies have reported the computer modeling, CAD design, and theoretical performance of single and multiple antenna arrays of Dual Concentric Conductor (DCC) square slot radiators driven at 915 and 433 MHz. Subsequently, practical CAD designs of microstrip antenna arrays constructed on thin and flexible printed circuit board (PCB) material were reported which evolved into large Conformal Microwave Array (CMA) sheets that could wrap around the surface of the human torso for delivering microwave energy to large areas of superficial tissue. Although uniform and adjustable radiation patterns have been demonstrated from multiple element applicators radiating into simple homogeneous phantom loads, the contoured and heterogeneous tissue loads typical of chestwall recurrent breast cancer have required additional design efforts to achieve good coupling and efficient heating from the increasingly larger conformal array applicators used to treat large area contoured patient anatomy. Thus recent work has extended the theoretical optimization of DCC antennas to improve radiation efficiency of each individual aperture and reduce mismatch reflections, radiation losses, noise, and cross coupling of the feedline distribution network of large array configurations. Design improvements have also been incorporated into the supporting bolus structure to maintain effective coupling of DCC antennas into contoured anatomy and to monitor and control surface temperatures under the entire array. New approaches for non-invasive monitoring of surface and sub-surface tissue temperatures under each independent heat source are described that make use of microwave radiometry and flexible sheet grid arrays of thermal sensors. Efforts to optimize the clinical patient interface and move from planar rectangular shapes to contoured vest applicators that accommodate entire disease in a larger number of patients are summarized. By applying heat more uniformly to large areas of contoured anatomy

  12. Ultra-stiff large-area carpets of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Meysami, Seyyed Shayan; Dallas, Panagiotis; Britton, Jude; Lozano, Juan G.; Murdock, Adrian T.; Ferraro, Claudio; Gutierrez, Eduardo Saiz; Rijnveld, Niek; Holdway, Philip; Porfyrakis, Kyriakos; Grobert, Nicole

    2016-06-01

    Herewith, we report the influence of post-synthesis heat treatment (<=2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm2) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, >=4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes.Herewith, we report the influence of post-synthesis heat treatment (<=2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm2) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under

  13. Attribution and Characterisation of Sclerophyll Forested Landscapes Over Large Areas

    NASA Astrophysics Data System (ADS)

    Jones, Simon; Soto-Berelov, Mariela; Suarez, Lola; Wilkes, Phil; Woodgate, Will; Haywood, Andrew

    2016-06-01

    This paper presents a methodology for the attribution and characterisation of Sclerophyll forested landscapes over large areas. First we define a set of woody vegetation data primitives (e.g. canopy cover, leaf area index (LAI), bole density, canopy height), which are then scaled-up using multiple remote sensing data sources to characterise and extract landscape woody vegetation features. The advantage of this approach is that vegetation landscape features can be described from composites of these data primitives. The proposed data primitives act as building blocks for the re-creation of past woody characterisation schemes as well as allowing for re-compilation to support present and future policy and management and decision making needs. Three main research sites were attributed; representative of different sclerophyll woody vegetated systems (Box Iron-bark forest; Mountain Ash forest; Mixed Species foothills forest). High resolution hyperspectral and full waveform LiDAR data was acquired over the three research sites. At the same time, land management agencies (Victorian Department of Environment, Land Water and Planning) and researchers (RMIT, CRC for Spatial Information and CSIRO) conducted fieldwork to collect structural and functional measurements of vegetation, using traditional forest mensuration transects and plots, terrestrial lidar scanning and high temporal resolution in-situ autonomous laser (VegNet) scanners. Results are presented of: 1) inter-comparisons of LAI estimations made using ground based hemispherical photography, LAI 2200 PCA, CI-110 and terrestrial and airborne laser scanners; 2) canopy height and vertical canopy complexity derived from airborne LiDAR validated using ground observations; and, 3) time-series characterisation of land cover features. 1. Accuracy targets for remotely sensed LAI products to match within ground based estimates are ± 0.5 LAI or a 20% maximum (CEOS/GCOS) with new aspirational targets of 5%). In this research we

  14. Large-area settlement pattern recognition from Landsat-8 data

    NASA Astrophysics Data System (ADS)

    Wieland, Marc; Pittore, Massimiliano

    2016-09-01

    The study presents an image processing and analysis pipeline that combines object-based image analysis with a Support Vector Machine to derive a multi-layered settlement product from Landsat-8 data over large areas. 43 image scenes are processed over large parts of Central Asia (Southern Kazakhstan, Kyrgyzstan, Tajikistan and Eastern Uzbekistan). The main tasks tackled by this work include built-up area identification, settlement type classification and urban structure types pattern recognition. Besides commonly used accuracy assessments of the resulting map products, thorough performance evaluations are carried out under varying conditions to tune algorithm parameters and assess their applicability for the given tasks. As part of this, several research questions are being addressed. In particular the influence of the improved spatial and spectral resolution of Landsat-8 on the SVM performance to identify built-up areas and urban structure types are evaluated. Also the influence of an extended feature space including digital elevation model features is tested for mountainous regions. Moreover, the spatial distribution of classification uncertainties is analyzed and compared to the heterogeneity of the building stock within the computational unit of the segments. The study concludes that the information content of Landsat-8 images is sufficient for the tested classification tasks and even detailed urban structures could be extracted with satisfying accuracy. Freely available ancillary settlement point location data could further improve the built-up area classification. Digital elevation features and pan-sharpening could, however, not significantly improve the classification results. The study highlights the importance of dynamically tuned classifier parameters, and underlines the use of Shannon entropy computed from the soft answers of the SVM as a valid measure of the spatial distribution of classification uncertainties.

  15. Holistic method for evaluating large area transparent conducting electrodes.

    PubMed

    Gupta, Ritu; Kulkarni, Giridhar U

    2013-02-01

    Nowadays, specifying the quality of a transparent conducting electrode (TCE) using a figure of merit (FoM) is considered nearly mandatory. However, not much attention is paid to the local variations in the FoM itself across the large area of the TCE. This calls for the definition of a local FoM (LFoM), particularly relevant with regard to several new generation TCEs which have been and are being proposed recently. A LFoM based on local measurements of transmission and sheet resistance, pixel by pixel, would be a Herculean task. The present article addresses this central issue by defining a LFoM based on the diffraction efficiency (DE) of a calibrated high-resolution transmission grating overlaid with a given TCE. The DE value, which critically depends on the periodic nature of the grating material, is shown to be highly sensitive to the various nonuniformities in the TCE overlaid on the grating, with length scales comparable to the grating period. The effectiveness of the so-defined LFoM was demonstrated using a pointer laser and a photodiode in combination with a transmission grating with ∼μm periodicity by taking ITO/glass and ITO/PET as case examples. A metal grating pattern of Cu deposited on seed Pd grating lines was fabricated as an example of new generation TCE and examined for FoM and LFoM, however, without the aid of the external grating. The LFoM based on DE presented here should serve as an excellent screening method for both conventional and emerging TCEs.

  16. Realization of Large-Area Wrinkle-Free Monolayer Graphene Films Transferred to Functional Substrates

    PubMed Central

    Park, Byeong-Ju; Choi, Jin-Seok; Kim, Hyun-Suk; Kim, Hyun-You; Jeong, Jong-Ryul; Choi, Hyung-Jin; Jung, Hyun-June; Jung, Min-Wook; An, Ki-Seok; Yoon, Soon-Gil

    2015-01-01

    Structural inhomogeneities, such as the wrinkles and ripples within a graphene film after transferring the free-standing graphene layer to a functional substrate, degrade the physical and electrical properties of the corresponding electronic devices. Here, we introduced titanium as a superior adhesion layer for fabricating wrinkle-free graphene films that is highly applicable to flexible and transparent electronic devices. The Ti layer does not influence the electronic performance of the functional substrates. Experimental and theoretical investigations confirm that the strong chemical interactions between Ti and any oxygen atoms unintentionally introduced on/within the graphene are responsible for forming the clean, defect-free graphene layer. Our results accelerate the practical application of graphene-related electronic devices with enhanced functionality. The large-area monolayer graphenes were prepared by a simple attachment of the Ti layer with the multi-layer wrinkle-free graphene films. For the first time, the graphene films were addressed for applications of superior bottom electrode for flexible capacitors instead of the novel metals. PMID:26043868

  17. Large-area multilayer infrared nano-wire grid polarizers

    NASA Astrophysics Data System (ADS)

    Gayduk, Alexey E.; Prinz, Victor Ya.; Seleznev, Vladimir A.; Rechkunov, Sergey N.

    2016-03-01

    We have developed a technology for fabricating infrared polarizers based on double- and four-layer metal-dielectric nanogratings. Due to the use of nanoimprint lithography, the size of fabricated samples with 190-nm grating period could be made exceeding 170 cm2. The fabricated polarizers are flexible, and they have high quality over the entire area of the sample. Spectrophotometric measurements and numerical simulations have showed that the polarizers exhibited a large transmission coefficient and a high extinction ratio (over 3 ṡ 104). In order to expand applications of polarizers to the bio-inspired wide field-of-view systems, technology for fabricating polarizers on curved surfaces prepared by 3D printing has been developed. The obtained results offer much promise for polarimetry purposes.

  18. Large-area multiplexed sensing using MEMS and fiber optics

    NASA Astrophysics Data System (ADS)

    Miller, Michael B.; Clark, Richard L., Jr.; Bell, Clifton R.; Russler, Patrick M.

    2000-06-01

    Micro-electro-mechanical (MEMS) technology offers the ability to implement local and independent sensing and actuation functions through the coordinated response of discrete micro-electro-mechanical 'basis function' elements. The small size of micromechanical components coupled with the ability to reduce costs using volume manufacturing techniques opens up significant potential not only in military applications such as flight and engine monitoring and control, but in autonomous vehicle control, smart munitions, airborne reconnaissance, LADAR, missile guidance, and even in intelligent transportation systems and automotive guidance applications. In this program, Luna Innovations is developing a flexible, programmable interface which can be integrated direction with different types of MEMS sensors, and then used to multiplex many sensors ona single optical fiber to provide a unique combination of functions that will allow larger quantities of sensory input with better resolution than ever before possible.

  19. The Spitzer-HETDEX Exploratory Large-area Survey

    NASA Astrophysics Data System (ADS)

    Papovich, C.; Shipley, H. V.; Mehrtens, N.; Lanham, C.; Lacy, M.; Ciardullo, R.; Finkelstein, S. L.; Bassett, R.; Behroozi, P.; Blanc, G. A.; de Jong, R. S.; DePoy, D. L.; Drory, N.; Gawiser, E.; Gebhardt, K.; Gronwall, C.; Hill, G. J.; Hopp, U.; Jogee, S.; Kawinwanichakij, L.; Marshall, J. L.; McLinden, E.; Mentuch Cooper, E.; Somerville, R. S.; Steinmetz, M.; Tran, K.-V.; Tuttle, S.; Viero, M.; Wechsler, R.; Zeimann, G.

    2016-06-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 μm with the Infrared Array Camera (IRAC) of the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers ≈24 deg2 of the Sloan Digital Sky Survey “Stripe 82” region, and falls within the footprints of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R ˜ 800 spectroscopy will produce ˜200,000 redshifts from the Lyα emission for galaxies in the range 1.9 < z < 3.5, and an additional ˜200,000 redshifts from the [O ii] emission for galaxies at z < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K-band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of ˜0.5 Gpc3 at 1.9 < z < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 μm images. The catalogs reach limiting sensitivities of 1.1 μJy at both 3.6 and 4.5 μm (1σ, for R = 2″ circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.

  20. Large-Area Permanent-Magnet ECR Plasma Source

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [<10(exp -4) torr (less than about 1.3 10(exp -2) Pa)] and input power <200 W at a frequency of 2.45 GHz. Though the prototype model operates at 2.45 GHz, operation at higher frequencies can be achieved by straightforward modification to the input microwave waveguide. Higher frequency operation may be desirable in those applications that require even higher background plasma densities. In the design of this ECR plasma source, there are no cumbersome, power-hungry electromagnets. The magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired

  1. The Spitzer-HETDEX Exploratory Large-area Survey

    NASA Astrophysics Data System (ADS)

    Papovich, C.; Shipley, H. V.; Mehrtens, N.; Lanham, C.; Lacy, M.; Ciardullo, R.; Finkelstein, S. L.; Bassett, R.; Behroozi, P.; Blanc, G. A.; de Jong, R. S.; DePoy, D. L.; Drory, N.; Gawiser, E.; Gebhardt, K.; Gronwall, C.; Hill, G. J.; Hopp, U.; Jogee, S.; Kawinwanichakij, L.; Marshall, J. L.; McLinden, E.; Mentuch Cooper, E.; Somerville, R. S.; Steinmetz, M.; Tran, K.-V.; Tuttle, S.; Viero, M.; Wechsler, R.; Zeimann, G.

    2016-06-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 μm with the Infrared Array Camera (IRAC) of the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers ≈24 deg2 of the Sloan Digital Sky Survey “Stripe 82” region, and falls within the footprints of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R ˜ 800 spectroscopy will produce ˜200,000 redshifts from the Lyα emission for galaxies in the range 1.9 < z < 3.5, and an additional ˜200,000 redshifts from the [O ii] emission for galaxies at z < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K-band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of ˜0.5 Gpc3 at 1.9 < z < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 μm images. The catalogs reach limiting sensitivities of 1.1 μJy at both 3.6 and 4.5 μm (1σ, for R = 2″ circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.

  2. Accounting for conformational flexibility and torsional anharmonicity in the H + CH{sub 3}CH{sub 2}OH hydrogen abstraction reactions: A multi-path variational transition state theory study

    SciTech Connect

    Meana-Pañeda, Rubén; Fernández-Ramos, Antonio

    2014-05-07

    This work reports a detailed theoretical study of the hydrogen abstraction reactions from ethanol by atomic hydrogen. The calculated thermal rate constants take into account torsional anharmonicity and conformational flexibility, in addition to the variational and tunneling effects. Specifically, the kinetics calculations were performed by using multi-path canonical variational transition state theory with least-action path tunneling corrections, to which we have added the two-dimensional non-separable method to take into account torsional anharmonicity. The multi-path thermal rate constant is expressed as a sum over conformational reaction channels. Each of these channels includes all the transition states that can be reached by internal rotations. The results show that, in the interval of temperatures between 250 and 2500 K, the account for multiple paths leads to higher thermal rate constants with respect to the single path approach, mainly at low and at high temperatures. In addition, torsional anharmonicity enhances the slope of the Arrhenius plot in this range of temperatures. Finally, we show that the incorporation of tunneling into the hydrogen abstraction reactions substantially changes the contribution of each of the transition states to the conformational reaction channel.

  3. Ultraclean and large-area monolayer hexagonal boron nitride on Cu foil using chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wen, Yao; Shang, Xunzhong; Dong, Ji; Xu, Kai; He, Jun; Jiang, Chao

    2015-07-01

    Atomically thin hexagonal boron nitride (h-BN) has been demonstrated to be an excellent dielectric layer as well as an ideal van der Waals epitaxial substrate for fabrication of two-dimensional (2D) atomic layers and their vertical heterostructures. Although many groups have obtained large-scale monolayer h-BN through low pressure chemical vapor deposition (LPCVD), it is still a challenge to grow clean monolayers without the reduction of domain size. Here we report the synthesis of large-area (4 × 2 cm2) high quality monolayer h-BN with an ultraclean and unbroken surface on copper foil by using LPCVD. A detailed investigation of the key factors affecting growth and transfer of the monolayer was carried out in order to eliminate the adverse effects of impurity particles. Furthermore, an optimized transfer approach allowed the nondestructive and clean transfer of the monolayer from copper foil onto an arbitrary substrate, including a flexible substrate, under mild conditions. Atomic force microscopy indicated that the root-mean-square (RMS) roughness of the monolayer h-BN on SiO2 was less than 0.269 nm for areas with fewer wrinkles. Selective area electron diffraction analysis of the h-BN revealed a pattern of hexagonal diffraction spots, which unambiguously demonstrated its highly crystalline character. Our work paves the way toward the use of ultraclean and large-area monolayer h-BN as the dielectric layer in the fabrication of high performance electronic and optoelectronic devices for novel 2D atomic layer materials.

  4. GLAST: Exploring Nature's Highest Energy Processes with the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Digel, Seth; Myers, J. D.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    The Gamma-ray Large Area Space Telescope (GLAST) is an international and multi-agency space mission that will study the cosmos in the energy range 10 keV-300 GeV. Several successful exploratory missions in gamma-ray astronomy led to the Energetic Gamma Ray Experiment Telescope (EGRET) instrument on the Compton Gamma Ray Observatory (CGRO). Launched in 1991, EGRET made the first complete survey of the sky in the 30 MeV-10 GeV range. EGRET showed the high-energy gamma-ray sky to be surprisingly dynamic and diverse, with sources ranging from the sun and moon to massive black holes at large redshifts. Most of the gamma-ray sources detected by EGRET remain unidentified. In light of the discoveries with EGRET, the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope vastly more capable than instruments flown previously, as well as a secondary instrument to augment the study of gamma-ray bursts. The main instrument, the Large Area Telescope (LAT), will have superior area, angular resolution, field of view, and deadtime that together will provide a factor of 30 or more advance in sensitivity, as well as provide capability for study of transient phenomena. The GLAST Burst Monitor (GBM) will have a field of view several times larger than the LAT and will provide spectral coverage of gamma-ray bursts that extends from the lower limit of the LAT down to 10 keV. The basic parameters of the GBM are compared to those of the Burst and Transient Source Experiment (BATSE) instrument on CGRO in Table 1-2. With the LAT and GBM, GLAST will be a flexible observatory for investigating the great range of astrophysical phenomena best studied in high-energy gamma rays. NASA plans to launch GLAST in late 2005.

  5. Laser two-photon polymerization micro- and nanostructuring over a large area on various substrates

    NASA Astrophysics Data System (ADS)

    Malinauskas, M.; Purlys, V.; Žukauskas, A.; Bickauskaite, G.; Gertus, T.; Danilevicius, P.; Paipulas, D.; Rutkauskas, M.; Gilbergs, H.; Baltriukiene, D.; Bukelskis, L.; Širmenis, R.; Bukelskiene, V.; Gadonas, R.; Sirvydis, V.; Piskarskas, A.

    2010-04-01

    A tightly focused ultrafast pulsed laser beam is guided into the volume of the photosensitive material and induces nonlinear photomodification. By translating the sample, the position of the focus is changed relatively, thus point-by-point complex 3D structures can be written inside the bulk. In this report, we present a Laser Two-Photon Polymerization (LTPP) setup for three-dimensional micro/nanostructuring for applications in photonics, microoptics, micromechanics, microfluidics and biomedicine. This system enables fabrication of functional devices over a large area (up to several cm in lateral size) with reproducible sub-micrometer resolution (up to 200 nm). In our experiments a Yb:KGW active media laser oscillator (75 fs, 200 kW, 515 nm frequency doubled, 80 MHz) was used as an irradiation source. The sample was mounted on XYZ wide range linear motor driven positioning stages having 10 nm positioning resolution. These stages enable an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support a linear scanning speed of up to 300 mm/s. Control of all the equipment was automated via custom made computer software "3D-Poli" specially designed for LTPP applications. The model of the structure can be imported as CAD file, this enables rapid and flexible structuring out of various photopolymers like ORMOCERs, ORMOSILs, acrylates and PEGDAs which are commonly used in conventional UV mask, nanoimprint and μ-stereolithographies. In this paper, we demonstrate polymeric microstructures fabricated over a large area on glass, plastic and metal substrates. This opens a way to produce functional devices like photonic crystals, microlenses, micromechanic and microfluidic components and artificial scaffolds as templates for cell growth. Additionally, results of primary myogenic stem cells expanding on microfabricated polymeric scaffolds are provided. Cell proliferation tests show the material and structure to be biocompatible for the

  6. Large Area Mountain Permafrost Simulation at DEM Resolution. Results from the European Alps and Himalaya

    NASA Astrophysics Data System (ADS)

    Fiddes, J.

    2015-12-01

    We present a system that is able to simulate land-surface conditions at continental scales while accounting for parameters that vary on order of 10's of metres (e.g., topography or surface cover) by using a statistical subgrid scheme (Fiddes and Gruber 2012). The model chain is driven by output from atmospheric datasets with a simple in-house downscaling scheme which uses only data on atmospheric pressure-levels and a DEM (Fiddes and Gruber 2014). The scheme has been tested in the case of mountain permafrost in the European Alps (Fiddes and Gruber 2015) with good results. However the strength of the scheme is application to remote data-sparse regions. Recently we have applied the scheme to simulate permafrost conditions in the Western Himalaya. This included a simple approach to correct snow mass balance using MODIS products, as input precipitation from atmospheric models may often have bias. The scheme is flexible in choice of atmospheric model input data, numerical surface model and surface data. In this abstract we will (1) present the model chain, (2) show the results of simulating permafrost conditions over large areas using only global datasets as input and (3) give an outlook to simulating future conditions. Fiddes, J., Endrizzi, S., and Gruber, S. 2015: Large-area land surface simulations in heterogeneous terrain driven by global data sets: application to mountain permafrost, The Cryosphere, 9, 411-426, doi:10.5194/tc-9-411-2015, 2015. http://dx.doi.org/10.5194/tc-9-411-2015Fiddes, J. & Gruber, S. 2014: TopoSCALE v.1.0: downscaling gridded climate data in complex terrain, Geoscientific Model Development, 7, 387-405, http://dx.doi.org/10.5194/gmd-7-387-2014Fiddes, J. & Gruber, S. 2012: TopoSUB: a tool for efficient large area numerical modelling in complex topography at sub-grid scales, Geoscientific Model Development, 5, 1245-1257,http://dx.doi.org/10.5194/gmd-5-1245-2012

  7. Ultrathin and lightweight organic solar cells with high flexibility

    PubMed Central

    Kaltenbrunner, Martin; White, Matthew S.; Głowacki, Eric D.; Sekitani, Tsuyoshi; Someya, Takao; Sariciftci, Niyazi Serdar; Bauer, Siegfried

    2012-01-01

    Application-specific requirements for future lighting, displays and photovoltaics will include large-area, low-weight and mechanical resilience for dual-purpose uses such as electronic skin, textiles and surface conforming foils. Here we demonstrate polymer-based photovoltaic devices on plastic foil substrates less than 2 μm thick, with equal power conversion efficiency to their glass-based counterparts. They can reversibly withstand extreme mechanical deformation and have unprecedented solar cell-specific weight. Instead of a single bend, we form a random network of folds within the device area. The processing methods are standard, so the same weight and flexibility should be achievable in light emitting diodes, capacitors and transistors to fully realize ultrathin organic electronics. These ultrathin organic solar cells are over ten times thinner, lighter and more flexible than any other solar cell of any technology to date. PMID:22473014

  8. Infrared photodissociation of a water molecule from a flexible molecule-H{sub 2}O complex: Rates and conformational product yields following XH stretch excitation

    SciTech Connect

    Clarkson, Jasper R.; Herbert, John M.; Zwier, Timothy S.

    2007-04-07

    Infrared-ultraviolet hole-burning and hole-filling spectroscopies have been used to study IR-induced dissociation of the tryptamine{center_dot}H{sub 2}O and tryptamine{center_dot}D{sub 2}O complexes. Upon complexation of a single water molecule, the seven conformational isomers of tryptamine collapse to a single structure that retains the same ethylamine side chain conformation present in the most highly populated conformer of tryptamine monomer. Infrared excitation of the tryptamine{center_dot}H{sub 2}O complex was carried out using a series of infrared absorptions spanning the range of 2470-3715 cm{sup -1}. The authors have determined the conformational product yield over this range and the dissociation rate near threshold, where it is slow enough to be measured by our methods. The observed threshold for dissociation occurred at 2872 cm{sup -1} in tryptamine{center_dot}H{sub 2}O and at 2869 cm{sup -1} in tryptamine{center_dot}D{sub 2}O, with no dissociation occurring on the time scale of the experiment ({approx}2 {mu}s) at 2745 cm{sup -1}. The dissociation time constants varied from {approx}200 ns for the 2869 cm{sup -1} band of tryptamine{center_dot}D{sub 2}O to {approx}25 ns for the 2872 cm{sup -1} band of tryptamine{center_dot}H{sub 2}O. This large isotope dependence is associated with a zero-point energy effect that increases the binding energy of the deuterated complex by {approx}190 cm{sup -1}, thereby reducing the excess energy available at the same excitation energy. At all higher energies, the dissociation lifetime was shorter than the pulse duration of our lasers (8 ns). At all wavelengths, the observed products in the presence of collisions are dominated by conformers A and B of tryptamine monomer, with small contributions from the other minor conformers. In addition, right at threshold (2869 cm{sup -1}), tryptamine{center_dot}D{sub 2}O dissociates exclusively to conformer A in the absence of collisions with helium, while both A and B conformational

  9. Topological analysis of HIV-1 glycoproteins expressed in situ on virus surfaces reveals tighter packing but greater conformational flexibility than for soluble gp120.

    PubMed

    Tong, Tommy; Osawa, Keiko; Robinson, James E; Crooks, Ema T; Binley, James M

    2013-08-01

    In natural infection, antibodies interact with HIV-1 primarily through nonfunctional forms of envelope glycoproteins (Env), including uncleaved (UNC) gp160 and gp41 stumps. These antigens are important to fully characterize, as they may be decoys that promote nonneutralizing responses and may also be targets for nonneutralizing effector responses. In this study, we compared the antigenic properties of Env expressed in situ on pseudovirion virus-like particle (VLP) surfaces and soluble gp120 using harmonized enzyme-linked immunosorbent assays (ELISAs) and a panel of 51 monoclonal antibodies (MAbs). Only 32 of 46 soluble gp120-reactive MAbs recognized the primary UNC gp160 antigen of VLPs. Indeed, many epitopes were poorly exposed (C1, V2, C1-C4, C4, C4-V3, CD4 induced [CD4i], and PGT group 3) or obscured (C2, C5, and C1-C5) on VLPs. In further studies, VLP Env exhibited an increased degree of inter-MAb competition, the epicenter of which was the base of the V3 loop, where PGT, 2G12, V3, and CD4 binding site specificities competed. UNC gp160 also underwent more drastic soluble CD4 (sCD4)-induced conformational changes than soluble gp120, exposing CD4i, C1-C4, and V2 epitopes. A greater propensity of UNC gp160 to undergo conformational changes was also suggested by the induction of CD4i MAb binding to VLPs by a V3 MAb as well as by soluble CD4. The same effect was not observed for soluble gp120. Taken together, our data suggest that membrane-expressed UNC gp160 exists in a less "triggered" conformational state than soluble gp120 and that MAb binding to UNC gp160 tends to have greater conformational consequences.

  10. Large-area alignment of tungsten oxide nanowires over flat and patterned substrates for room-temperature gas sensing.

    PubMed

    Cheng, Wei; Ju, Yanrui; Payamyar, Payam; Primc, Darinka; Rao, Jingyi; Willa, Christoph; Koziej, Dorota; Niederberger, Markus

    2015-01-01

    Alignment of nanowires over a large area of flat and patterned substrates is a prerequisite to use their collective properties in devices such as gas sensors. In this work, uniform single-crystalline ultrathin W18 O49 nanowires with diameters less than 2 nm and aspect ratios larger than 100 have been synthesized, and, despite their flexibility, assembled into thin films with high orientational order over a macroscopic area by the Langmuir-Blodgett technique. Alignment of the tungsten oxide nanowires was also possible on top of sensor substrates equipped with electrodes. Such sensor devices were found to exhibit outstanding sensitivity to H2 at room temperature. PMID:25412600

  11. Large-area thermoelectric high-aspect-ratio nanostructures by atomic layer deposition.

    PubMed

    Ruoho, Mikko; Juntunen, Taneli; Tittonen, Ilkka

    2016-09-01

    We report on the thermoelectric properties of large-area high-aspect-ratio nanostructures. We fabricate the structures by atomic layer deposition of conformal ZnO thin films on track-etched polycarbonate substrate. The resulting structure consists of ZnO tubules which continue through the full thickness of the substrate. The electrical and thermal properties of the structures are studied both in-plane and out-of-plane. They exhibit very low out-of-plane thermal conductivity down to 0.15 W m(-1) K(-1) while the in-plane sheet resistance of the films was found to be half that of the same film on glass substrate, allowing material-independent doubling of output power of any planar thin-film thermoelectric generator. The wall thickness of the fabricated nanotubes was varied within a range of up to 100 nm. The samples show polycrystalline nature with (002) preferred crystal orientation. PMID:27454037

  12. Single-Step Soft-Imprinted Large-Area Nanopatterned Antireflection Coating.

    PubMed

    van de Groep, Jorik; Spinelli, Pierpaolo; Polman, Albert

    2015-06-10

    We demonstrate an effective nanopatterned antireflection coating on glass that is based on sol-gel chemistry and large-area substrate-conformal soft-imprint technology. The printed 120 nm tall silica nanocylinders with a diameter of 245 nm in a square array with 325 nm pitch form an effective-index (n = 1.20) antireflection coating that reduces the double-sided reflection from a borosilicate glass slide from 7.35% to 0.57% (averaged over the visible spectral range) with a minimum reflectance <0.05% at 590 nm. The nanoglass coating is made using a simple process involving only spin-coating and an imprint step, without vacuum technology or annealing required. The refractive index of the nanoglass layers can be tailored over a broad range by controlling the geometry (1.002 < n < 1.44 in theory), covering a wide range that is not achievable with natural materials. We demonstrate that the nanoglass coating effectively eliminates glare from smart-phone display windows and significantly improves the efficiency of glass-encapsulated solar cells. These features, that are achieved over an angular range as wide as ±50°, together with strong hydrophobicity and mechanical durability, make nanoglass coatings a promising technology to improve the functionality of optoelectronic devices based on glass encapsulation. PMID:26010375

  13. Large-Area Sub-Wavelength Optical Patterning via Long-Range Ordered Polymer Lens Array.

    PubMed

    Wu, Jin; Liow, Chihao; Tao, Kai; Guo, Yuanyuan; Wang, Xiaotian; Miao, Jianmin

    2016-06-29

    Fabrication of large-area, highly orderly, and high-resolution nanostructures in a cost-effective fashion prompts advances in nanotechnology. Herein, for the first time, we demonstrate a unique strategy to prepare a long-range highly regular polymer lens from photoresist nanotrenches based templates, which are obtained from underexposure. The relationship between exposure dose and the cross-sectional morphology of produced photoresist nanostructures is revealed for the first time. The polymer lens arrays are repeatedly used for rapid generation of sub-100 nm nanopatterns across centimeter-scale areas. The light focusing properties of the nanoscale polymer lens are investigated by both simulation and experiment. It is found that the geometry, size of the lens, and the exposure dose can be deployed to adjust the produced feature size, spacing, and shapes. Because the polymer lenses are derived from top-down photolithography, the nearly perfect long-range periodicity of produced nanopatterns is ensured, and the feature shapes can be flexibly designed. Because this nanolithographic strategy enables subwavelength periodical nanopatterns with controllable feature size, geometry, and composition in a cost-effective manner, it can be optimized as a viable and potent nanofabrication tool for various technological applications. PMID:27301636

  14. Enhanced light emission from large-area monolayer MoS₂ using plasmonic nanodisc arrays.

    PubMed

    Butun, Serkan; Tongay, Sefaattin; Aydin, Koray

    2015-04-01

    Single-layer direct band gap semiconductors such as transition metal dichalcogenides are quite attractive for a wide range of electronics, photonics, and optoelectronics applications. Their monolayer thickness provides significant advantages in many applications such as field-effect transistors for high-performance electronics, sensor/detector applications, and flexible electronics. However, for optoelectronics and photonics applications, inherent monolayer thickness poses a significant challenge for the interaction of light with the material, which therefore results in poor light emission and absorption behavior. Here, we demonstrate enhanced light emission from large-area monolayer MoS2 using plasmonic silver nanodisc arrays, where enhanced photoluminescence up to 12-times has been measured. Observed phenomena stem from the fact that plasmonic resonance couples to both excitation and emission fields and thus boosts the light-matter interaction at the nanoscale. Reported results allow us to engineer light-matter interactions in two-dimensional materials and could enable highly efficient photodetectors, sensors, and photovoltaic devices, where photon absorption and emission efficiency highly dictate the device performance.

  15. Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics.

    PubMed

    Bucella, Sadir G; Luzio, Alessandro; Gann, Eliot; Thomsen, Lars; McNeill, Christopher R; Pace, Giuseppina; Perinot, Andrea; Chen, Zhihua; Facchetti, Antonio; Caironi, Mario

    2015-09-25

    High-mobility semiconducting polymers offer the opportunity to develop flexible and large-area electronics for several applications, including wearable, portable and distributed sensors, monitoring and actuating devices. An enabler of this technology is a scalable printing process achieving uniform electrical performances over large area. As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics. By combining pre-aggregating solvents for formulating the semiconductor and by adopting a room temperature wired bar-coating technique, here we demonstrate the fast deposition of submonolayers and nanostructured films of a model electron-transporting polymer. Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm(2) V(-1) s(-1), allowing very simple device architectures to operate at 3.3 MHz. Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits.

  16. Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics

    PubMed Central

    Bucella, Sadir G.; Luzio, Alessandro; Gann, Eliot; Thomsen, Lars; McNeill, Christopher R.; Pace, Giuseppina; Perinot, Andrea; Chen, Zhihua; Facchetti, Antonio; Caironi, Mario

    2015-01-01

    High-mobility semiconducting polymers offer the opportunity to develop flexible and large-area electronics for several applications, including wearable, portable and distributed sensors, monitoring and actuating devices. An enabler of this technology is a scalable printing process achieving uniform electrical performances over large area. As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics. By combining pre-aggregating solvents for formulating the semiconductor and by adopting a room temperature wired bar-coating technique, here we demonstrate the fast deposition of submonolayers and nanostructured films of a model electron-transporting polymer. Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm2 V−1 s−1, allowing very simple device architectures to operate at 3.3 MHz. Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits. PMID:26403619

  17. Applications of large-area nanopatterning to energy generation and storage devices

    NASA Astrophysics Data System (ADS)

    Mills, Eric N.

    This dissertation encompasses the creation and testing of nanostructured, electrochemically-active energy generation and storage devices, and development of the associated fabrication techniques. The fabricated devices include nanopatterned, plasmonically-active, TiO2+Au thin films for Photocatalytic Water Splitting (PCW), TiO2-based Dye-Sensitized Solar Cells (DSSCs) incorporating nanopatterned, plasmonically-active metallic front electrodes, and Si nanopillar anodes for Li-ion batteries. Techniques were also developed for encapsulation and removal of wet-etched Si nanowires from their mother substrates. TiO2 was the first material to be widely used for PCW. Its use is hampered by its large bandgap (~3.2eV), and poor recombination lifetimes. Au nanoparticles (NPs) have been previously used to improve recombination lifetimes in TiO2 by separating photogenerated carriers near the NP edges, and to increase photocurrents by injecting plasmonically-excited hot electrons into the TiO2 conduction band. Using nanostructured TiO 2+Au electrodes, we aim to increase the PCW efficiency of TiO2 -based electrodes. Dye-sensitized solar cells (DSSCs) employ visible-absorbing dyes anchored to a high-surface-area semiconducting scaffold. The front transparent conducting electrode (TCE) is typically ITO, a scarce and expensive material. We aim to increase the efficiency of thin-film DSSCs and eliminate the use of ITO by using a metallic subwavelength array (MESH) of nanoholes as the front TCE. Silicon holds promise as a high-capacity anode material for Li-ion batteries, as it can store ~10x the Li of graphite, the current leading anode material (3569 vs. 372 mAh/g). However, Si undergoes dramatic (>300%) volume expansion upon "lithiation", pulverizing any structure with non-nanoscopic dimensions (>250nm). We created large-area arrays of "nanopillars" with sub-100nm diameters, using roll-to-roll-compatible flexible-mold NIL on commercially-available metal substrates. Ordered

  18. Conformation and hydration of aspartame.

    PubMed

    Kang, Y K

    1991-07-01

    Conformational free energy calculations using an empirical potential (ECEPP/2) and the hydration shell model were carried out on the neutral, acidic, zwitterionic, and basic forms of aspartame in the hydrated state. The results indicate that as the molecule becomes more charged, the number of low energy conformations becomes smaller and the molecule becomes less flexible. The calculated free energies of hydration of charged aspartames show that hydration has a significant effect on the conformation in solution. Only two feasible conformations were found for the zwitterionic form, and these are consistent with the conformations deduced from NMR and X-ray diffraction experiments. The calculated free energy difference between these two conformations was 1.25 kcal/mol. The less favored of the two solvated conformations can be expected to be stabilized by hydrophobic interaction of the phenyl groups in the crystal.

  19. The structural basis for optimal performance of oligothiophene-based fluorescent amyloid ligands: conformational flexibility is essential for spectral assignment of a diversity of protein aggregates.

    PubMed

    Klingstedt, Therése; Shirani, Hamid; Åslund, K O Andreas; Cairns, Nigel J; Sigurdson, Christina J; Goedert, Michel; Nilsson, K Peter R

    2013-07-29

    Protein misfolding diseases are characterized by deposition of protein aggregates, and optical ligands for molecular characterization of these disease-associated structures are important for understanding their potential role in the pathogenesis of the disease. Luminescent conjugated oligothiophenes (LCOs) have proven useful for optical identification of a broader subset of disease-associated protein aggregates than conventional ligands, such as thioflavin T and Congo red. Herein, the molecular requirements for achieving LCOs able to detect nonthioflavinophilic Aβ aggregates or non-congophilic prion aggregates, as well as spectrally discriminate Aβ and tau aggregates, were investigated. An anionic pentameric LCO was subjected to chemical engineering by: 1) replacing thiophene units with selenophene or phenylene moieties, or 2) alternating the anionic substituents along the thiophene backbone. In addition, two asymmetric tetrameric ligands were generated. Overall, the results from this study identified conformational freedom and extended conjugation of the conjugated backbone as crucial determinants for obtaining superior thiophene-based optical ligands for sensitive detection and spectral assignment of disease-associated protein aggregates.

  20. Flexible vs Rigid Epitope Conformations for Diagnostic- and Vaccine-Oriented Applications: Novel Insights from the Burkholderia pseudomallei BPSL2765 Pal3 Epitope.

    PubMed

    Gori, Alessandro; Peri, Claudio; Quilici, Giacomo; Nithichanon, Arnone; Gaudesi, Davide; Longhi, Renato; Gourlay, Louise; Bolognesi, Martino; Lertmemongkolchai, Ganjana; Musco, Giovanna; Colombo, Giorgio

    2016-03-11

    Peptides seldom retain stable conformations if separated from their native protein structure. In an immunological context, this potentially affects the development of selective peptide-based bioprobes and, from a vaccine perspective, poses inherent limits in the elicitation of cross-reactive antibodies by candidate epitopes. Here, a 1,4-disubstituted-1,2,3-triazole-mediated stapling strategy was used to stabilize the native α-helical fold of the Pal3 peptidic epitope from the protein antigen PalBp (BPSL2765) from Burkholderia pseudomallei, the etiological agent of melioidosis. Whereas Pal3 shows no propensity to fold outside its native protein context, the engineered peptide (Pal3H) forms a stable α-helix, as assessed by MD, NMR, and CD structural analyses. Importantly, Pal3H shows an enhanced ability to discriminate between melioidosis patient subclasses in immune sera reactivity tests, demonstrating the potential of the stapled peptide for diagnostic purposes. With regard to antibody elicitation and related bactericidal activities, the linear peptide is shown to elicit a higher response. On these bases, we critically discuss the implications of epitope structure engineering for diagnostic- and vaccine-oriented applications. PMID:27623032

  1. Conformational flexibility related to enzyme activity: evidence for a dynamic active-site gatekeeper function of Tyr215 in Aerococcus viridans lactate oxidase

    PubMed Central

    Stoisser, Thomas; Brunsteiner, Michael; Wilson, David K.; Nidetzky, Bernd

    2016-01-01

    L-Lactate oxidase (LOX) belongs to a large family of flavoenzymes that catalyze oxidation of α-hydroxy acids. How in these enzymes the protein structure controls reactivity presents an important but elusive problem. LOX contains a prominent tyrosine in the substrate binding pocket (Tyr215 in Aerococcus viridans LOX) that is partially responsible for securing a flexible loop which sequesters the active site. To characterize the role of Tyr215, effects of substitutions of the tyrosine (Y215F, Y215H) were analyzed kinetically, crystallographically and by molecular dynamics simulations. Enzyme variants showed slowed flavin reduction and oxidation by up to 33-fold. Pyruvate release was also decelerated and in Y215F, it was the slowest step overall. A 2.6-Å crystal structure of Y215F in complex with pyruvate shows the hydrogen bond between the phenolic hydroxyl and the keto oxygen in pyruvate is replaced with a potentially stronger hydrophobic interaction between the phenylalanine and the methyl group of pyruvate. Residues 200 through 215 or 216 appear to be disordered in two of the eight monomers in the asymmetric unit suggesting that they function as a lid controlling substrate entry and product exit from the active site. Substitutions of Tyr215 can thus lead to a kinetic bottleneck in product release. PMID:27302031

  2. Conformational flexibility in the apolipoprotein E amino-terminal domain structure determined from three new crystal forms: implications for lipid binding.

    PubMed Central

    Segelke, B. W.; Forstner, M.; Knapp, M.; Trakhanov, S. D.; Parkin, S.; Newhouse, Y. M.; Bellamy, H. D.; Weisgraber, K. H.; Rupp, B.

    2000-01-01

    An amino-terminal fragment of human apolipoprotein E3 (residues 1-165) has been expressed and crystallized in three different crystal forms under similar crystallization conditions. One crystal form has nearly identical cell dimensions to the previously reported orthorhombic (P2(1)2(1)2(1)) crystal form of the amino-terminal 22 kDa fragment of apolipoprotein E (residues 1-191). A second orthorhombic crystal form (P2(1)2(1)2(1) with cell dimensions differing from the first form) and a trigonal (P3(1)21) crystal form were also characterized. The structures of the first orthorhombic and the trigonal form were determined by seleno-methionine multiwavelength anomalous dispersion, and the structure of the second orthorhombic form was determined by molecular replacement using the structure from the trigonal form as a search model. A combination of modern experimental and computational techniques provided high-quality electron-density maps, which revealed new features of the apolipoprotein E structure, including an unambiguously traced loop connecting helices 2 and 3 in the four-helix bundle and a number of multiconformation side chains. The three crystal forms contain a common intermolecular, antiparallel packing arrangement. The electrostatic complimentarity observed in this antiparallel packing resembles the interaction of apolipoprotein E with the monoclonal antibody 2E8 and the low density lipoprotein receptor. Superposition of the model structures from all three crystal forms reveals flexibility and pronounced kinks in helices near one end of the four-helix bundle. This mobility at one end of the molecule provides new insights into the structural changes in apolipoprotein E that occur with lipid association. PMID:10850798

  3. Packaging and modular assembly of large-area and fine-pitch 2-D ultrasonic transducer arrays.

    PubMed

    Lin, Der-Song; Wodnicki, Robert; Zhuang, Xuefeng; Woychik, Charles; Thomenius, Kai E; Fisher, Rayette A; Mills, David M; Byun, Albert J; Burdick, William; Khuri-Yakub, Pierre; Bonitz, Barry; Davies, Todd; Thomas, Glen; Otto, Bernd; Töpper, Michael; Fritzsch, Thomas; Ehrmann, Oswin

    2013-07-01

    A promising transducer architecture for largearea arrays employs 2-D capacitive micromachined ultrasound transducer (CMUT) devices with backside trench-frame pillar interconnects. Reconfigurable array (RA) application-specified integrated circuits (ASICs) can provide efficient interfacing between these high-element-count transducer arrays and standard ultrasound systems. Standard electronic assembly techniques such as flip-chip and ball grid array (BGA) attachment, along with organic laminate substrate carriers, can be leveraged to create large-area arrays composed of tiled modules of CMUT chips and interface ASICs. A large-scale, fully populated and integrated 2-D CMUT array with 32 by 192 elements was developed and demonstrates the feasibility of these techniques to yield future large-area arrays. This study demonstrates a flexible and reliable integration approach by successfully combining a simple under-bump metallization (UBM) process and a stacked CMUT/interposer/ASIC module architecture. The results show high shear strength of the UBM (26.5 g for 70-μm balls), high interconnect yield, and excellent CMUT resonance uniformity (s = 0.02 MHz). A multi-row linear array was constructed using the new CMUT/interposer/ASIC process using acoustically active trench-frame CMUT devices and mechanical/ nonfunctional Si backside ASICs. Imaging results with the completed probe assembly demonstrate a functioning device based on the modular assembly architecture. PMID:25004504

  4. Large area substrate for surface enhanced Raman spectroscopy (SERS) using glass-drawing technique

    DOEpatents

    Ivanov, Ilia N.; Simpson, John T.

    2012-06-26

    A method of making a large area substrate comprises drawing a plurality of tubes to form a plurality of drawn tubes, and cutting the plurality of drawn tubes into cut drawn tubes. Each cut drawn tube has a first end and a second end along the longitudinal direction of the respective cut drawn tube. The cut drawn tubes collectively have a predetermined periodicity. The method of making a large area substrate also comprises forming a metal layer on the first ends of the cut drawn tubes to provide a large area substrate.

  5. High throughput fabrication of large-area plasmonic color filters by soft-X-ray interference lithography.

    PubMed

    Sun, Libin; Hu, Xiaolin; Wu, Qingjun; Wang, Liansheng; Zhao, Jun; Yang, Shumin; Tai, Renzhong; Fecht, Hans-Jorg; Zhang, Dong-Xian; Wang, Li-Qiang; Jiang, Jian-Zhong

    2016-08-22

    Plasmonic color filters in mass production have been restricted from current fabrication technology, which impede their applications. Soft-X-ray interference lithography (XIL) has recently generated considerable interest as a newly developed technique for the production of periodic nano-structures with resolution theoretically below 4 nm. Here we ameliorate XIL by adding an order sorting aperture and designing the light path properly to achieve perfect-stitching nano-patterns and fast fabrication of large-area color filters. The fill factor of nanostructures prepared on ultrathin Ag films can largely affect the transmission minimum of plasmonic color filters. By changing the fill factor, the color can be controlled flexibly, improving the utilization efficiency of the mask in XIL simultaneously. The calculated data agree well with the experimental results. Finally, an underlying mechanism has been uncovered after systematically analyzing the localized surface plasmon polaritons (LSPPs) coupling in electric field distribution. PMID:27557190

  6. Large area crop inventory experiment crop assessment subsystem software requirements document

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The functional data processing requirements are described for the Crop Assessment Subsystem of the Large Area Crop Inventory Experiment. These requirements are used as a guide for software development and implementation.

  7. Large-area, lithography-free, low-cost SERS sensor with good flexibility and high performance.

    PubMed

    Jiang, Jing; Xu, Zhida; Ameen, Abid; Ding, Fei; Lin, Guohong; Liu, Gang Logan

    2016-09-23

    Cost-effective, sensitive and bio-compatible surface-enhanced Raman spectroscopy (SERS) substrate has been in high demand since the Raman spectrum was designated as a significant tool for analyzing the composition of liquids, gases and solids in 1998 [1]. In this research, we presented the design, fabrication and characterization of an improved gold-based SERS substrate. With fine tuning of the SiO2 thickness we achieved a 3.391 times improvement and achieved an enhancement factor of 1.55 * 10(7) which is 15 times better than the current gold-standard Klarite substrate. Such improvement is ascribed to the localized surface plasmon resonance (SPR) and propagating SPR, which is proved by full-wave finite-difference time-domain simulations. PMID:27540828

  8. Large-area, lithography-free, low-cost SERS sensor with good flexibility and high performance

    NASA Astrophysics Data System (ADS)

    Jiang, Jing; Xu, Zhida; Ameen, Abid; Ding, Fei; Lin, Guohong; Logan Liu, Gang

    2016-09-01

    Cost-effective, sensitive and bio-compatible surface-enhanced Raman spectroscopy (SERS) substrate has been in high demand since the Raman spectrum was designated as a significant tool for analyzing the composition of liquids, gases and solids in 1998 [1]. In this research, we presented the design, fabrication and characterization of an improved gold-based SERS substrate. With fine tuning of the SiO2 thickness we achieved a 3.391 times improvement and achieved an enhancement factor of 1.55 * 107 which is 15 times better than the current gold-standard Klarite substrate. Such improvement is ascribed to the localized surface plasmon resonance (SPR) and propagating SPR, which is proved by full-wave finite-difference time-domain simulations.

  9. Combining large area fluorescence with multiphoton microscopy for improved detection of oral epithelial neoplasia (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pal, Rahul; Yang, Jinping; Qiu, Suimin; McCammon, Susan; Resto, Vicente; Vargas, Gracie

    2016-03-01

    Volumetric Multiphoton Autofluorescence Microscopy (MPAM) and Second Harmonic Generation Microscopy (SHGM) show promise for revealing indicators of neoplasia representing the complex microstructural organization of mucosa, potentially providing high specificity for detection of neoplasia, but is limited by small imaging area. Large area fluorescence methods on the other hand show high sensitivity appropriate for screening but are hampered by low specificity. In this study, we apply MPAM-SHGM following guidance from large area fluorescence, by either autofluorescence or a targeted metabolic fluorophore, as a potentially clinically viable approach for detection of oral neoplasia. Sites of high neoplastic potentially were identified by large area red/green autofluorescence or by a fluorescently labelled deoxy-glucose analog, 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose (2-NBDG) to highlight areas of high glucose uptake across the buccal pouch of a hamster model for OSCC. Follow-up MPAM-SHGM was conducted on regions of interests (ROIs) to assess whether microscopy would reveal microscopic features associated with neoplasia to confirm or exclude large area fluorescence findings. Parameters for analysis included cytologic metrics, 3D epithelial connective tissue interface metrics (MPAM-SHGM) and intensity of fluorescence (widefield). Imaged sites were biopsied and processed for histology and graded by a pathologist. A small sample of human ex vivo tissues were also imaged. A generalized linear model combining image metrics from large area fluorescence and volumetric MPAM-SHGM indicated the ability to delineate normal and inflammation from neoplasia.

  10. CVD diamond wafers as large-area thermoluminescence detectors for measuring the spatial distribution of dose

    NASA Astrophysics Data System (ADS)

    Marczewska, B.; Bilski, P.; Olko, P.; Olko, P.; Nesládek, M.; Bergonzo, P.; Rbisz, M.; Waligórski, M. P. R.

    2003-09-01

    The applicability of large-area CVD diamond wafers (diameter about 5 cm, thickness about 0.1 mm), read out as thermoluminescence (TL) detectors, for assessing two-dimensional (2-D) dose distribution over their area, was investigated. To obtain 2-D TL images, a special TL reader equipped with large-area planchet and a CCD camera instead of the usual PM tube was developed. Several 2-D TL images: of an alpha source (Am-241), a Ra-226 needle source and a Ru-106 ophthalmic applicator, were measured and high-resolution digital images obtained. Our preliminary results demonstrate the potential capability of large-area CVD diamond wafers, read out as TL detectors, in 2-D dosimetry for medical applications. (

  11. Impact of substrate characteristics on performance of large area plasmonic photoconductive emitters.

    PubMed

    Yardimci, Nezih T; Salas, Rodolfo; Krivoy, Erica M; Nair, Hari P; Bank, Seth R; Jarrahi, Mona

    2015-12-14

    We present a comprehensive analysis of terahertz radiation from large area plasmonic photoconductive emitters in relation with characteristics of device substrate. Specifically, we investigate the radiation properties of large area plasmonic photoconductive emitters fabricated on GaAs substrates that exhibit short carrier lifetimes through low-temperature substrate growth and through epitaxially embedded rare-earth arsenide (ErAs and LuAs) nanoparticles in superlattice structures. Our analysis indicates that the utilized substrate composition and growth process for achieving short carrier lifetimes are crucial in determining substrate resistivity, carrier drift velocity, and carrier lifetime, which directly impact optical-to-terahertz conversion efficiency, radiation power, radiation bandwidth, and reliability of large area plasmonic photoconductive emitters.

  12. Large-Area Chemical and Biological Decontamination Using a High Energy Arc Lamp (HEAL) System.

    SciTech Connect

    Duty, Chad E; Smith, Rob R; Vass, Arpad Alexander; Ilgner, Ralph H; Brown, Gilbert M

    2008-01-01

    Methods for quickly decontaminating large areas exposed to chemical and biological (CB) warfare agents can present significant logistical, manpower, and waste management challenges. Oak Ridge National Laboratory (ORNL) is pursuing an alternate method to decompose CB agents without the use of toxic chemicals or other potentially harmful substances. This process uses a high energy arc lamp (HEAL) system to photochemically decompose CB agents over large areas (12 m2). Preliminary tests indicate that more than 5 decades (99.999%) of an Anthrax spore simulant (Bacillus globigii) were killed in less than 7 seconds of exposure to the HEAL system. When combined with a catalyst material (TiO2) the HEAL system was also effective against a chemical agent simulant, diisopropyl methyl phosphonate (DIMP). These results demonstrate the feasibility of a rapid, large-area chemical and biological decontamination method that does not require toxic or corrosive reagents or generate hazardous wastes.

  13. Design of a broadband ultra-large area acoustic cloak based on a fluid medium

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

    2014-10-01

    A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

  14. 110 GHz measurement of large-area graphene integrated in low-loss microwave structures

    NASA Astrophysics Data System (ADS)

    Skulason, H. S.; Nguyen, H. V.; Guermoune, A.; Sridharan, V.; Siaj, M.; Caloz, C.; Szkopek, T.

    2011-10-01

    We report high-frequency scattering parameter measurement of large-area monolayer graphene integrated on low-loss quartz substrates. High-quality graphene was grown by chemical vapour deposition on copper, chemically hole doped, and transferred to quartz. Microwave measurements were performed from 0.01 to 110 GHz. Simple microwave models were used to extract graphene impedance parameters. We find that contact resistance is effectively shunted above 3 GHz. Atomically thin large area graphene behaves as a wideband resistor with negligible kinetic inductance and negligible skin effect.

  15. System and method for interfacing large-area electronics with integrated circuit devices

    DOEpatents

    Verma, Naveen; Glisic, Branko; Sturm, James; Wagner, Sigurd

    2016-07-12

    A system and method for interfacing large-area electronics with integrated circuit devices is provided. The system may be implemented in an electronic device including a large area electronic (LAE) device disposed on a substrate. An integrated circuit IC is disposed on the substrate. A non-contact interface is disposed on the substrate and coupled between the LAE device and the IC. The non-contact interface is configured to provide at least one of a data acquisition path or control path between the LAE device and the IC.

  16. A novel photovoltaic power system which uses a large area concentrator mirror

    NASA Technical Reports Server (NTRS)

    Arrison, Anne; Fatemi, Navid

    1987-01-01

    A preliminary analysis has been made of a novel photovoltaic power system concept. The system is composed of a small area, dense photovoltaic array, a large area solar concentrator, and a battery system for energy storage. The feasibility of such a system is assessed for space power applications. The orbital efficiency, specific power, mass, and area of the system are calculated under various conditions and compared with those for the organic Rankine cycle solar dynamic system proposed for Space Station. Near term and advanced large area concentrator photovoltaic systems not only compare favorably to solar dynamic systems in terms of performance but offer other benefits as well.

  17. A novel method for the activity measurement of large-area beta reference sources.

    PubMed

    Stanga, D; De Felice, P; Keightley, J; Capogni, M; Ioan, M R

    2016-03-01

    A novel method has been developed for the activity measurement of large-area beta reference sources. It makes use of two emission rate measurements and is based on the weak dependence between the source activity and the activity distribution for a given value of transmission coefficient. The method was checked experimentally by measuring the activity of two ((60)Co and (137)Cs) large-area reference sources constructed from anodized aluminum foils. Measurement results were compared with the activity values measured by gamma spectrometry. For each source, they agree within one standard uncertainty and also agree within the same limits with the certified values of the source activity. PMID:26701656

  18. An Analysis Methodology for the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Morris, Robin D.; Cohen-Tanugi, Johann

    2004-01-01

    The Large Area Telescope (LAT) instrument on the Gamma Ray Large Area Space Telescope (GLAST) has been designed to detect high-energy gamma rays and determine their direction of incidence and energy. We propose a reconstruction algorithm based on recent advances in statistical methodology. This method, alternative to the standard event analysis inherited from high energy collider physics experiments, incorporates more accurately the physical processes occurring in the detector, and makes full use of the statistical information available. It could thus provide a better estimate of the direction and energy of the primary photon.

  19. Multiscale conformal pattern transfer.

    PubMed

    Lodewijks, Kristof; Miljkovic, Vladimir; Massiot, Inès; Mekonnen, Addis; Verre, Ruggero; Olsson, Eva; Dmitriev, Alexandre

    2016-01-01

    We demonstrate a method for seamless transfer from a parent flat substrate of basically any lithographic top-down or bottom-up pattern onto essentially any kind of surface. The nano- or microscale patterns, spanning macroscopic surface areas, can be transferred with high conformity onto a large variety of surfaces when such patterns are produced on a thin carbon film, grown on top of a sacrificial layer. The latter allows lifting the patterns from the flat parent substrate onto a water-air interface to be picked up by the host surface of choice. We illustrate the power of this technique by functionalizing broad range of materials including glass, plastics, metals, rough semiconductors and polymers, highlighting the potential applications in in situ colorimetry of the chemistry of materials, anti-counterfeit technologies, biomolecular and biomedical studies, light-matter interactions at the nanoscale, conformal photovoltaics and flexible electronics. PMID:27329824

  20. Multiscale conformal pattern transfer

    PubMed Central

    Lodewijks, Kristof; Miljkovic, Vladimir; Massiot, Inès; Mekonnen, Addis; Verre, Ruggero; Olsson, Eva; Dmitriev, Alexandre

    2016-01-01

    We demonstrate a method for seamless transfer from a parent flat substrate of basically any lithographic top-down or bottom-up pattern onto essentially any kind of surface. The nano- or microscale patterns, spanning macroscopic surface areas, can be transferred with high conformity onto a large variety of surfaces when such patterns are produced on a thin carbon film, grown on top of a sacrificial layer. The latter allows lifting the patterns from the flat parent substrate onto a water-air interface to be picked up by the host surface of choice. We illustrate the power of this technique by functionalizing broad range of materials including glass, plastics, metals, rough semiconductors and polymers, highlighting the potential applications in in situ colorimetry of the chemistry of materials, anti-counterfeit technologies, biomolecular and biomedical studies, light-matter interactions at the nanoscale, conformal photovoltaics and flexible electronics. PMID:27329824

  1. Multiscale conformal pattern transfer

    NASA Astrophysics Data System (ADS)

    Lodewijks, Kristof; Miljkovic, Vladimir; Massiot, Inès; Mekonnen, Addis; Verre, Ruggero; Olsson, Eva; Dmitriev, Alexandre

    2016-06-01

    We demonstrate a method for seamless transfer from a parent flat substrate of basically any lithographic top-down or bottom-up pattern onto essentially any kind of surface. The nano- or microscale patterns, spanning macroscopic surface areas, can be transferred with high conformity onto a large variety of surfaces when such patterns are produced on a thin carbon film, grown on top of a sacrificial layer. The latter allows lifting the patterns from the flat parent substrate onto a water-air interface to be picked up by the host surface of choice. We illustrate the power of this technique by functionalizing broad range of materials including glass, plastics, metals, rough semiconductors and polymers, highlighting the potential applications in in situ colorimetry of the chemistry of materials, anti-counterfeit technologies, biomolecular and biomedical studies, light-matter interactions at the nanoscale, conformal photovoltaics and flexible electronics.

  2. Independent Peer Evaluation of the Large Area Crop Inventory Experiment (LACIE): The LACIE Symposium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Yield models and crop estimate accuracy are discussed within the Large Area Crop Inventory Experiment. The wheat yield estimates in the United States, Canada, and U.S.S.R. are emphasized. Experimental results design, system implementation, data processing systems, and applications were considered.

  3. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications.

    PubMed

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-01-01

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K(-1)m(-1), down to the ultra-low κ = 0.55 ± 0.10 W K(-1)m(-1) value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials. PMID:27650202

  4. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications

    PubMed Central

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-01-01

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K−1m−1, down to the ultra-low κ = 0.55 ± 0.10 W K−1m−1 value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials. PMID:27650202

  5. LARGE AREA LAND COVER MAPPING THROUGH SCENE-BASED CLASSIFICATION COMPOSITING

    EPA Science Inventory

    Over the past decade, a number of initiatives have been undertaken to create definitive national and global data sets consisting of precision corrected Landsat MSS and TM scenes. One important application of these data is the derivation of large area land cover products spanning ...

  6. Transformational, Large Area Fabrication of Nanostructured Materials Using Plasma Arc Lamps

    SciTech Connect

    2009-03-01

    This factsheet describes a study that will address critical additional steps over large areas of as-synthesized nanostructured materials, such as annealing, phase transformation, or activation of dopants, dramatically reducing the processing costs of the solid-state lighting and photovoltaic materials.

  7. Detecting Change in Landscape Greenness over Large Areas: An Example for New Mexico, USA

    EPA Science Inventory

    Monitoring and quantifying changes in vegetation cover over large areas using remote sensing can potentially detect large-scale, slow changes (e.g., climate change), as well as more local and rapid changes (e.g., fire, land development). A useful indicator for detecting change i...

  8. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications.

    PubMed

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-09-21

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K(-1)m(-1), down to the ultra-low κ = 0.55 ± 0.10 W K(-1)m(-1) value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials.

  9. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications

    NASA Astrophysics Data System (ADS)

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-09-01

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K‑1m‑1, down to the ultra-low κ = 0.55 ± 0.10 W K‑1m‑1 value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials.

  10. LEAP - A LargE Area Burst Polarimeter for the ISS

    NASA Astrophysics Data System (ADS)

    McConnell, M. L.; LEAP Collaboration

    2016-10-01

    The LargE Area burst Polarimeter (LEAP) is a mission concept for a 50-500 keV Compton scatter polarimeter instrument that would be deployed on the ISS. It will be proposed as an astrophysics Mission of Opportunity (MoO) in late 2016.

  11. Improve large area uniformity and production capacity of laser interference lithography with beam flattening device

    NASA Astrophysics Data System (ADS)

    Yang, Yin-Kuang; Wu, Yu-Xiang; Lin, Te-Hsun; Yu, Chun-Wen; Fu, Chien-Chung

    2016-03-01

    Laser interference lithography (LIL) is a maskless lithography technique with many advantages such as simple optical design, inexpensive, infinite depth of focus, and large area patterning with single exposure. However, the intensity of normal laser beam is Gaussian distribution. In order to obtain large area uniform structure, we have to expand the laser beam much bigger than the wafer and use only the center part of the beam. Resulting in wasting lots of energy and the production capacity decrease. In this study, we designed a beam shaping device which consists of two parallel fused silicon optical window with different coating on both side. Two optical window form an air thin film. When the expanded laser beam pass through the device, the beam will experience many refraction and reflection between two optical window and interference with each other. The transmittance of laser beam will depend on the incident angle. The output intensity distribution will change from Gaussian distribution to a flat top distribution. In our experiment, we combined the beam shaping device with a Lloyd's mirror LIL system. Experiment results indicated that the LIL system with beam shaping device can obtain large area uniform pattern. And compare with the traditional Lloyd's mirror LIL system, the exposure time is shorten up to 4.5 times. In conclusion, this study design a beam flattening device for LIL system. The flat top beam can improve the large area uniformity and the production capacity of LIL. Making LIL more suitable for industry application.

  12. Large-area high-quality graphene on Ge(001)/Si(001) substrates.

    PubMed

    Pasternak, I; Dabrowski, P; Ciepielewski, P; Kolkovsky, V; Klusek, Z; Baranowski, J M; Strupinski, W

    2016-06-01

    Various experimental data revealing large-area high-quality graphene films grown by the CVD method on Ge(001)/Si(001) substrates are presented. SEM images have shown that the structure of nano-facets is formed on the entire surface of Ge(001), which is covered by a graphene layer over the whole macroscopic sample surface of 1 cm(2). The hill-and-valley structures are positioned 90° to each other and run along the <100> direction. The hill height in relation to the valley measured by STM is about 10 nm. Raman measurements have shown that a uniform graphene monolayer covers the nano-facet structures on the Ge(001) surface. Raman spectroscopy has also proved that the grown graphene monolayer is characterized by small strain variations and minimal charge fluctuations. Atomically resolved STM images on the hills of the nanostructures on the Ge(001) surface have confirmed the presence of a graphene monolayer. In addition, the STS/CITS maps show that high-quality graphene has been obtained on such terraces. The subsequent coalescence of graphene domains has led to a relatively well-oriented large-area layer. This is confirmed by LEED measurements, which have indicated that two orientations are preferable in the grown large-area graphene monolayer. The presence of large-area coverage by graphene has been also confirmed by low temperature Hall measurements of a macroscopic sample, showing an n-type concentration of 9.3 × 10(12) cm(-2) and a mobility of 2500 cm(2) V(-1) s(-1). These important characteristic features of graphene indicate a high homogeneity of the layer grown on the large area Ge(001)/Si(001) substrates. PMID:27189131

  13. Large-area high-quality graphene on Ge(001)/Si(001) substrates

    NASA Astrophysics Data System (ADS)

    Pasternak, I.; Dabrowski, P.; Ciepielewski, P.; Kolkovsky, V.; Klusek, Z.; Baranowski, J. M.; Strupinski, W.

    2016-05-01

    Various experimental data revealing large-area high-quality graphene films grown by the CVD method on Ge(001)/Si(001) substrates are presented. SEM images have shown that the structure of nano-facets is formed on the entire surface of Ge(001), which is covered by a graphene layer over the whole macroscopic sample surface of 1 cm2. The hill-and-valley structures are positioned 90° to each other and run along the <100> direction. The hill height in relation to the valley measured by STM is about 10 nm. Raman measurements have shown that a uniform graphene monolayer covers the nano-facet structures on the Ge(001) surface. Raman spectroscopy has also proved that the grown graphene monolayer is characterized by small strain variations and minimal charge fluctuations. Atomically resolved STM images on the hills of the nanostructures on the Ge(001) surface have confirmed the presence of a graphene monolayer. In addition, the STS/CITS maps show that high-quality graphene has been obtained on such terraces. The subsequent coalescence of graphene domains has led to a relatively well-oriented large-area layer. This is confirmed by LEED measurements, which have indicated that two orientations are preferable in the grown large-area graphene monolayer. The presence of large-area coverage by graphene has been also confirmed by low temperature Hall measurements of a macroscopic sample, showing an n-type concentration of 9.3 × 1012 cm-2 and a mobility of 2500 cm2 V-1 s-1. These important characteristic features of graphene indicate a high homogeneity of the layer grown on the large area Ge(001)/Si(001) substrates.

  14. Large-area perovskite nanowire arrays fabricated by large-scale roll-to-roll micro-gravure printing and doctor blading

    NASA Astrophysics Data System (ADS)

    Hu, Qiao; Wu, Han; Sun, Jia; Yan, Donghang; Gao, Yongli; Yang, Junliang

    2016-02-01

    Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ~45%, temperature ~28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays with great potential applications in flexible electronic and optoelectronic devices.Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ~45%, temperature ~28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays

  15. Fast and large-area growth of uniform MoS2 monolayers on molybdenum foils

    NASA Astrophysics Data System (ADS)

    Tai, Guoan; Zeng, Tian; Yu, Jin; Zhou, Jianxin; You, Yuncheng; Wang, Xufeng; Wu, Hongrong; Sun, Xu; Hu, Tingsong; Guo, Wanlin

    2016-01-01

    A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the formed monolayers can be nondestructively transferred onto arbitrary substrates by removing the Mo foil using diluted ferric chloride solution and can be successfully fabricated into photodetectors. The results show a novel avenue to efficiently fabricate two-dimensional crystals in a large area in a highly controllable way and should have great potential for the development of large-scale applications of two-dimensional crystals in electrophotonic systems.A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the

  16. Facile electrochemical transfer of large-area single crystal epitaxial graphene from Ir(1 1 1)

    NASA Astrophysics Data System (ADS)

    Koefoed, Line; Kongsfelt, Mikkel; Ulstrup, Søren; Grubišić Čabo, Antonija; Cassidy, Andrew; Whelan, Patrick R.; Bianchi, Marco; Dendzik, Maciej; Pizzocchero, Filippo; Jørgensen, Bjarke; Bøggild, Peter; Hornekær, Liv; Hofmann, Philip; Pedersen, Steen U.; Daasbjerg, Kim

    2015-03-01

    High-quality growth of graphene and subsequent reliable transfer to insulating substrates are needed for various technological applications, such as flexible screens and high speed electronics. In this paper, we present a new electrochemical method for the transfer of large-area, high-quality single crystalline graphene from Ir(1 1 1) to Si/SiO2 under ambient conditions. The method is based on intercalation of tetraoctylammonium ions between the graphene layer and the Ir surface. This simple technique allows transfer of graphene single crystals having the same size as the substrate they are grown on (diameter ≈7 mm). In addition, the substrate can be reused for further growth cycles. A detailed Raman map analysis of the transferred graphene reveals straight lines, in which the Raman peaks characteristic for graphene are shifted. These lines originate from scratches in the Ir(1 1 1) crystal introduced by the polishing procedure. Furthermore, areas with numerous wrinkles exist inbetween these lines, forming a network across the entire graphene crystal. Hence, the initial characteristics and imprints left on the sheet of graphene in terms of strain and wrinkles from the growth process remain after transfer.

  17. High-Resolution, Large-Area Fabrication of Compliant Electrodes via Laser Ablation for Robust, Stretchable Dielectric Elastomer Actuators and Sensors.

    PubMed

    Araromi, Oluwaseun A; Rosset, Samuel; Shea, Herbert R

    2015-08-19

    A key element in stretchable actuators, sensors, and systems based on elastomer materials are compliant electrodes. While there exist many methodologies for fabricating electrodes on dielectric elastomers, very few succeed in achieving high-resolution patterning over large areas. We present a novel approach for the production of mechanically robust, high-resolution compliant electrodes for stretchable silicone elastomer actuators and sensors. Cast, 2-50 μm thick poly(dimethylsiloxane) (PDMS)-carbon composite layers are patterned by laser ablation and subsequently bonded to a PDMS membrane by oxygen plasma activation. The technique affords great design flexibility and high resolution and readily scales to large-area arrays of devices. We validate our methodology by producing arrays of actuators and sensors on up to A4-size substrates, reporting on microscale dielectric elastomer actuators (DEA) generating area strains of over 25%, and interdigitated capacitive touch sensors with high sensitivity yet insensitivity to substrate stretching. We demonstrate the ability to cofabricate highly integrated multifunctional transducers using the same process flow, showing the methodology's promise in realizing sophisticated and reliable complex stretchable devices with fine features over large areas.

  18. Large-Area Synthesis of High-Quality Uniform Few-Layer MoTe2.

    PubMed

    Zhou, Lin; Xu, Kai; Zubair, Ahmad; Liao, Albert D; Fang, Wenjing; Ouyang, Fangping; Lee, Yi-Hsien; Ueno, Keiji; Saito, Riichiro; Palacios, Tomás; Kong, Jing; Dresselhaus, Mildred S

    2015-09-23

    The controlled synthesis of large-area, atomically thin molybdenum ditelluride (MoTe2) crystals is crucial for its various applications based on the attractive properties of this emerging material. In this work, we developed a chemical vapor deposition synthesis to produce large-area, uniform, and highly crystalline few-layer 2H and 1T' MoTe2 films. It was found that these two different phases of MoTe2 can be grown depending on the choice of Mo precursor. Because of the highly crystalline structure, the as-grown few-layer 2H MoTe2 films display electronic properties that are comparable to those of mechanically exfoliated MoTe2 flakes. Our growth method paves the way for the large-scale application of MoTe2 in high-performance nanoelectronics and optoelectronics. PMID:26305492

  19. Improved time response for large area microchannel plate photomultiplier tubes in fusion diagnostics

    SciTech Connect

    Milnes, J. S. Conneely, T. M.; Howorth, J.; Horsfield, C. J.

    2014-11-15

    Fusion diagnostics that utilise high speed scintillators often need to capture a large area of light with a high degree of time accuracy. Microchannel plate (MCP) photomultiplier tubes (PMTs) are recognised as the leading device for capturing fast optical signals. However, when manufactured in their traditional proximity focused construction, the time response performance is reduced as the active area increases. This is due to two main factors: the capacitance of a large anode and the difficulty of obtaining small pore MCPs with a large area. Collaboration between Photek and AWE has produced prototype devices that combine the excellent time response of small area MCP-PMTs with a large active area by replacing the traditional proximity-gap front section with an electro-optically focused photocathode to MCP. We present results from both single and double MCP devices with a 40 mm diameter active area and show simulations for the 100 mm device being built this year.

  20. Performance of the Anti-Coincidence Detector on the GLAST Large Area Telescope

    SciTech Connect

    Thompson, D.J.; Charles, E.; Hartman, R.C.; Moiseev, A.A.; Ormes, J.F.; /NASA, Goddard /Denver U.

    2007-10-22

    The Anti-Coincidence Detector (ACD), the outermost detector layer in the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT), is designed to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly-charged relativistic particles, but must also have a low probability for self-veto of high-energy gammas by backsplash radiation from interactions in the LAT calorimeter. Simulations and tests demonstrate that the ACD meets its design requirements. The performance of the ACD has remained stable through stand-alone environmental testing, shipment across the U.S., installation onto the LAT, shipment back across the U.S., LAT environmental testing, and shipment to Arizona. As part of the fully-assembled GLAST observatory, the ACD is being readied for final testing before launch.

  1. Field effect tuning of microwave Faraday rotation and isolation with large-area graphene

    NASA Astrophysics Data System (ADS)

    Skulason, Helgi S.; Sounas, Dimitrios L.; Mahvash, Farzaneh; Francoeur, Sebastien; Siaj, Mohamed; Caloz, Christophe; Szkopek, Thomas

    2015-08-01

    We have demonstrated field effect tuning of microwave frequency Faraday rotation in magnetically biased large-area graphene in a hollow circular waveguide isolator geometry. Oxidized intrinsic silicon was used as a microwave transparent back-gate for large-area graphene devices. A 26 dB modulation of isolation in the K-band was achieved with a gate voltage modulation of 10 V corresponding to a carrier density modulation of 7 × 10 11 /cm2. We have developed a simple analytical model for transmission and isolation of the structure. Field effect modulation of Faraday rotation can be extended to other two dimensional electronic systems and is anticipated to be useful for gate voltage controlled isolators, circulators, and other non-reciprocal devices.

  2. A green synthesis method for large area silver thin film containing nanoparticles.

    PubMed

    Shinde, N M; Lokhande, A C; Lokhande, C D

    2014-07-01

    The green synthesis method is inexpensive and convenient for large area deposition of thin films. For the first time, a green synthesis method for large area silver thin film containing nanoparticles is reported. Silver nanostructured films are deposited using silver nitrate solution and guava leaves extract. The study confirmed that the reaction time plays a key role in the growth and shape/size control of silver nanoparticles. The properties of silver films are studied using UV-visible spectrophotometer, scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle, Fourier-transform Raman (FT-Raman) spectroscopy and Photoluminescence (PL) techniques. Finally, as an application, these films are used effectively in antibacterial activity study. PMID:24836517

  3. The Anti-Coincidence Detector for the GLAST Large Area Telescope

    SciTech Connect

    Moiseev, A.A.; Hartman, R.C.; Ormes, J.F.; Thompson, D.J.; Amato, M.J.; Johnson, T.E.; Segal, K.N.; Sheppard, D.A.

    2007-03-23

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.

  4. Large area mapping of soil moisture using the ESTAR passive microwave radiometer

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Levine, D. M.; Swift, C. T.; Schmugge, T. J.

    1994-01-01

    Investigations designed to study land surface hydrologic-atmospheric interactions, showing the potential of L band passive microwave radiometry for measuring surface soil moisture over large areas, are discussed. Satisfying the data needs of these investigations requires the ability to map large areas rapidly. With aircraft systems this means a need for more beam positions over a wider swath on each flightline. For satellite systems the essential problem is resolution. Both of these needs are currently being addressed through the development and verification of Electronically Scanned Thinned Array Radiometer (ESTAR) technology. The ESTAR L band radiometer was evaluated for soil moisture mapping applications in two studies. The first was conducted over the semiarid rangeland Walnut Gulch watershed located in south eastern Arizona (U.S.). The second was performed in the subhumid Little Washita watershed in south west Oklahoma (U.S.). Both tests showed that the ESTAR is capable of providing soil moisture with the same level of accuracy as existing systems.

  5. Toward Large-Area Sub-Arcsecond X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Aldcroft, Thomas L.; Allured, Ryan; Atkins, Carolyn; Burrows, David N.; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Cotroneo, Vincenzo; Elsner, Ronald F.; Graham, Michael E.; Gubarev, Mikhail V.; Heilmann, Ralf K.; Johnson-Wilke, Raegan L.; Kilaru, Kiranmayee; Kolodziejczak, Jeffrey J.; McMuldroch, Stuart; Ramsey, Brian D.; Reid, Paul B.; Riveros, Raul E.; Roche, Jacqueline M.; Saha, Timo T.; Schattenburg, Mark L.; Schwartz, Daniel A.; Trolier-McKinstry, Susan E.; Ulmer, Melville P.; Vaynman, Semyon; Vikhlinin, Alexey; Wang, Xiaoli; Weisskopf, Martin C.; Wilke, Rudeger H. T.; Zhang, William W.

    2014-01-01

    The future of x-ray astronomy depends upon development of x-ray telescopes with larger aperture areas (>1 sq m) and finer angular resolution(<1).Combined with the special requirements of nested grazing incidence optics, the mass and envelope constraints of spaceborne telescopes render such advances technologically challenging. Achieving this goal will require precision fabrication, alignment, mounting, and assembly of large areas (>100 sq m) of lightweight (1 kg/sq m areal density) high quality mirrors-possibly entailing active (in-space adjustable) alignment and figure correction. This paper discusses relevant programmatic and technological issues and summarizes progress toward large area sub-arcsecond x-ray telescopes. Key words: X-ray telescopes, x-ray optics, active optics, electroactive devices, silicon mirrors, differential deposition, ion implantation.

  6. Very Large Area/Volume Microwave ECR Plasma and Ion Source

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor); Patterson, Michael J. (Inventor)

    2009-01-01

    The present invention is an apparatus and method for producing very large area and large volume plasmas. The invention utilizes electron cyclotron resonances in conjunction with permanent magnets to produce dense, uniform plasmas for long life ion thruster applications or for plasma processing applications such as etching, deposition, ion milling and ion implantation. The large area source is at least five times larger than the 12-inch wafers being processed to date. Its rectangular shape makes it easier to accommodate to materials processing than sources that are circular in shape. The source itself represents the largest ECR ion source built to date. It is electrodeless and does not utilize electromagnets to generate the ECR magnetic circuit, nor does it make use of windows.

  7. Extraordinary suppression of carrier scattering in large area graphene oxide films

    SciTech Connect

    Negishi, R. Kobayashi, Y.

    2014-12-22

    In this study, we find that thermal treatment in ethanol vapor has a remarkable suppression effect of carrier scattering occurring between reduced graphene oxide (rGO) flakes in large area films. We observe excellent electrical properties such as high carrier mobility (∼5 cm{sup 2}/Vs) and low sheet resistance (∼40 KΩ/□) for the rGO films. From the electrical conductivity analysis of large area rGO films using two-dimensional variable range hopping model and structural analysis using Raman spectra measured from the rGO films, we reveal that the significant effect is caused by the expansion of conjugated π-electron system in rGO flake due to the efficient restoration of graphitic structure.

  8. Circular polarization dependent cyclotron resonance in large-area graphene in ultrahigh magnetic fields

    NASA Astrophysics Data System (ADS)

    Booshehri, L. G.; Mielke, C. H.; Rickel, D. G.; Crooker, S. A.; Zhang, Q.; Ren, L.; Hároz, E. H.; Rustagi, A.; Stanton, C. J.; Jin, Z.; Sun, Z.; Yan, Z.; Tour, J. M.; Kono, J.

    2012-05-01

    Using ultrahigh magnetic fields up to 170 T and polarized midinfrared radiation with tunable wavelengths from 9.22 to 10.67 μm, we studied cyclotron resonance in large-area graphene grown by chemical vapor deposition. Circular polarization dependent studies reveal strong p-type doping for as-grown graphene, and the dependence of the cyclotron resonance on radiation wavelength allows for a determination of the Fermi energy. Thermal annealing shifts the Fermi energy to near the Dirac point, resulting in the simultaneous appearance of hole and electron cyclotron resonance in the magnetic quantum limit, even though the sample is still p-type, due to graphene's linear dispersion and unique Landau level structure. These high-field studies therefore allow for a clear identification of cyclotron resonance features in large-area, low-mobility graphene samples.

  9. Large-area semi-transparent light-sensitive nanocrystal skins.

    PubMed

    Akhavan, Shahab; Guzelturk, Burak; Sharma, Vijay Kumar; Demir, Hilmi Volkan

    2012-11-01

    We report a large-area, semi-transparent, light-sensitive nanocrystal skin (LS-NS) platform consisting of single monolayer colloidal nanocrystals. LS-NS devices, which were fabricated over areas up to 48 cm(2) using spray-coating and several cm-squares using dip-coating, are operated on the principle of photogenerated potential buildup, unlike the conventional charge collection. Implementing proof-of-concept devices using CdTe nanocrystals with ligand removal, we observed a substantial sensitivity enhancement factor of ~73%, accompanied with a 3-fold faster response time (<100 ms). With fully sealed nanocrystal monolayers, LS-NS is found to be highly stable under ambient conditions, promising for low-cost large-area UV/visible sensing in windows and facades of smart buildings. PMID:23187342

  10. Lithography-free large-area metamaterials for stable thermophotovoltaic energy conversion

    DOE PAGESBeta

    Coppens, Zachary J.; Kravchenko, Ivan I.; Valentine, Jason G.

    2016-02-08

    A large-area metamaterial thermal emitter is fabricated using facile, lithography-free techniques. The device is composed of conductive oxides, refractory ceramics, and noble metals and shows stable, selective emission after exposure to 1173 K for 22 h in oxidizing and inert atmospheres. Lastly, the results indicate that the metamaterial can be used to achieve high-performance thermophotovoltaic devices for applications such as portable power generation.

  11. Hot-electron flux observation in large-area microwave sustained plasmas

    NASA Astrophysics Data System (ADS)

    Kudela, Jozef; Terebessy, Tibor; Kando, Masashi

    2000-03-01

    Flux of hot electrons directed away from the waveguiding plasma-dielectric interface was experimentally observed in large-area microwave discharges. The energy of these electrons attains values of some 60 eV, and they are believed to be originating from the resonantly-enhanced electric field region localized near the dielectric. The phenomenon appears to play a significant role in discharge heating mechanism, which is demonstrated by plasma parameter profiles.

  12. A novel lithography technique for formation of large areas of uniform nanostructures

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Dey, Dibyendu; Memis, Omer G.; Katsnelson, Alex; Mohseni, Hooman

    2008-08-01

    With nanotechnology becoming widely used, many applications such as plasmonics, sensors, storage devices, solar cells, nano-filtration and artificial kidneys require the structures with large areas of uniform periodic nanopatterns. Most of the current nano-manufacturing techniques, including photolithography, electron-beam lithography, and focal ion beam milling, are either slow or expensive to be applied into the areas. Here, we demonstrate an alternative and novel lithography technique - Nanosphere Photolithography (NSP) - that generates a large area of highly uniform periodic nanoholes or nanoposts by utilizing the monolayer of hexagonally close packed (HCP) silica microspheres as super-lenses on top of photoresist. The size of the nanopatterns generated is almost independent of the sphere sizes and hence extremely uniform patterns can be obtained. We demonstrate that the method can produce hexagonally packed arrays of hole of sub-250 nm size in positive photoresist using a conventional exposure system with a broadband UV source centered at 400 nm. We also show a large area of highly uniform gold nanoholes (~180 nm) and nanoposts (~300nm) array with the period of 1 μm fabricated by the combination of lift-off and NSP. The process is not limited to gold. Similar structures have been shown with aluminum and silicon dioxide layer. The period and size of the structures can also be tuned by changing proper parameters. The technique applying self-assembled and focusing properties of micro-/nano-spheres into photolithography establishes a new paradigm for mask-less photolithography technique, allowing rapid and economical creation of large areas of periodic nanostructures with a high throughput.

  13. Fabrication of CdZnTe strip detectors for large area arrays

    SciTech Connect

    Stahle, C.M.; Shi, Z.Q.; Hu, K.

    1998-12-31

    A CdZnTe strip detector large area array ({approximately} 60 cm{sup 2} with 36 detectors) with capabilities for high resolution imaging and spectroscopy has been built as a prototype for a space flight gamma ray burst instrument. The detector array also has applications in nuclear medical imaging. Two dimensional orthogonal strip detectors with 100 {micro}m pitch have been fabricated and tested. Details for the array design, fabrication and evaluation of the detectors will be presented.

  14. Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area

    SciTech Connect

    Liu, Linyue Zhang, Xianpeng; Zhong, Yunhong; Ouyang, Xiaoping Zhang, Jianfu

    2014-01-15

    Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

  15. Caustic Recycle from Hanford Tank Waste Using Large Area NaSICON Structures (LANS)

    SciTech Connect

    Fountain, Matthew S.; Sevigny, Gary J.; Balagopal, S.; Bhavaraju, S.

    2009-03-31

    This report presents the results of a 5-day test of an electrochemical bench-scale apparatus using a proprietary (NAS-GY) material formulation of a (Na) Super Ion Conductor (NaSICON) membrane in a Large Area NaSICON Structures (LANS) configuration. The primary objectives of this work were to assess system performance, membrane seal integrity, and material degradation while removing Na from Group 5 and 6 tank waste from the Hanford Site.

  16. Self-assembly and nanosphere lithography for large-area plasmonic patterns on graphene.

    PubMed

    Lotito, Valeria; Zambelli, Tomaso

    2015-06-01

    Plasmonic structures on graphene can tailor its optical properties, which is essential for sensing and optoelectronic applications, e.g. for the enhancement of photoresponsivity of graphene photodetectors. Control over their structural and, hence, spectral properties can be attained by using electron beam lithography, which is not a viable solution for the definition of patterns over large areas. For the fabrication of large-area plasmonic nanostructures, we propose to use self-assembled monolayers of nanospheres as a mask for metal evaporation and etching processes. An optimized approach based on self-assembly at air/water interface with a properly designed apparatus allows the attainment of monolayers of hexagonally closely packed patterns with high long-range order and large area coverage; special strategies are devised in order to protect graphene against damage resulting from surface treatment and further processing steps such as reactive ion etching, which could potentially impair graphene properties. Therefore we demonstrate that nanosphere lithography is a cost-effective solution to create plasmonic patterns on graphene.

  17. Fast and large-area growth of uniform MoS2 monolayers on molybdenum foils.

    PubMed

    Tai, Guoan; Zeng, Tian; Yu, Jin; Zhou, Jianxin; You, Yuncheng; Wang, Xufeng; Wu, Hongrong; Sun, Xu; Hu, Tingsong; Guo, Wanlin

    2016-01-28

    A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the formed monolayers can be nondestructively transferred onto arbitrary substrates by removing the Mo foil using diluted ferric chloride solution and can be successfully fabricated into photodetectors. The results show a novel avenue to efficiently fabricate two-dimensional crystals in a large area in a highly controllable way and should have great potential for the development of large-scale applications of two-dimensional crystals in electrophotonic systems.

  18. Simple room-temperature preparation of high-yield large-area graphene oxide.

    PubMed

    Huang, N M; Lim, H N; Chia, C H; Yarmo, M A; Muhamad, M R

    2011-01-01

    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO. PMID:22267928

  19. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar

    NASA Astrophysics Data System (ADS)

    Swatantran, Anu; Tang, Hao; Barrett, Terence; Decola, Phil; Dubayah, Ralph

    2016-06-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km2). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping.

  20. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar

    PubMed Central

    Swatantran, Anu; Tang, Hao; Barrett, Terence; DeCola, Phil; Dubayah, Ralph

    2016-01-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km2). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping. PMID:27329078

  1. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar.

    PubMed

    Swatantran, Anu; Tang, Hao; Barrett, Terence; DeCola, Phil; Dubayah, Ralph

    2016-06-22

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km(2)). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping.

  2. Simple room-temperature preparation of high-yield large-area graphene oxide.

    PubMed

    Huang, N M; Lim, H N; Chia, C H; Yarmo, M A; Muhamad, M R

    2011-01-01

    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.

  3. Fast and large-area growth of uniform MoS2 monolayers on molybdenum foils.

    PubMed

    Tai, Guoan; Zeng, Tian; Yu, Jin; Zhou, Jianxin; You, Yuncheng; Wang, Xufeng; Wu, Hongrong; Sun, Xu; Hu, Tingsong; Guo, Wanlin

    2016-01-28

    A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the formed monolayers can be nondestructively transferred onto arbitrary substrates by removing the Mo foil using diluted ferric chloride solution and can be successfully fabricated into photodetectors. The results show a novel avenue to efficiently fabricate two-dimensional crystals in a large area in a highly controllable way and should have great potential for the development of large-scale applications of two-dimensional crystals in electrophotonic systems. PMID:26743938

  4. Large Area Superconducting TES Spiderweb Bolometer for Multi-mode Cavity Microwave Detect

    NASA Astrophysics Data System (ADS)

    Biasotti, M.; Bagliani, D.; Corsini, D.; De Bernardis, P.; Gatti, F.; Gualtieri, R.; Lamagna, L.; Masi, S.; Pizzigoni, G.; Schillaci, A.

    2014-05-01

    For the cosmic microwave background, the increase of the sensitivity of present superconducting TES Spiderweb Bolometers can be done coupling them to a large set of modes of the EM radiation inside the cavity. This will require a proper shaping of the horn-cavity assembly for the focal plane of the microwave telescope and the use of large area bolometers. Large area spiderweb bolometers of 8 mm diameter and a mesh size of 250 μm are fabricated in order to couple with approximately the first 20 modes of the cavity at about 140 GHz. These bolometers are fabricated with micro machining techniques from silicon wafer covered with SiO2 - Si3N4 CVD thick films, 0.3 μm and 1 μm respectively. The sensor is a Ti/Au/Ti 3 layer TES sensor with Tc tuned in the 330-380 mK and 2 mK transition width. The TES is electronically coupled to the EM gold absorber that is grown on to the spiderweb mesh in order to sense the temperature of the electron gas heated by the EM radiation. The gold absorber mesh has 5 um beam size over a Si3N4 10 μm beam size supporting mesh. The Si3N4 mesh is then fully suspended by means of DRIE back etching of the Si substrate. Here we present the first results of these large area bolometers.

  5. Design, Production and Testing of Cost-Effective, Large-Area, MCP-based Planar Photodetectors

    NASA Astrophysics Data System (ADS)

    Xie, Junqi; Byrum, Karen; Demarteau, Marcel; Noonan, John; Setru, Sagar; Virgo, Mathew; Wagner, Robert; Walters, Dean; Wang, Xing; Xia, Lei; Zhao, Huyue

    2014-03-01

    Microchannel plate (MCP)-based photodetectors with large-area, thin planar geometry and glass-body assembly, are considered as next generation photodetector to replace photomultiplier tubes. They have shown significant potential for applications in high energy collider physics and astrophysics. Due to the extreme sensitivity of the photocathode to water and oxygen, the production of this kind of photodetectors requires photocathodes to be transferred under high vacuum. A new photodetector production facility at Argonne National Laboratory was designed and constructed. The facility aims to produce small form-factor, MCP-based photodetectors completely made out of glass. 6 x 6 cm2 photodetectors using metal and alkali antimonide as photocathode are currently under production. An overview of the production sequence and first performance results will be presented. Scaling up the production to larger form-factor devices will be discussed. The challenge of sealing a large area photodetector has recently been overcome. Windows with 20 × 20 cm2 active photocathode area were successfully sealed and progress towards large-area photodetector production progress will be reported.

  6. Testing of a Neon Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin Lee

    2014-01-01

    Cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks is required for future NASA missions. A cryogenic loop heat pipe (CLHP) can provide a closed-loop cooling system for this purpose and has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A neon CLHP was tested extensively in a thermal vacuum chamber using a cryopump as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components. Tests conducted included loop cool-down from the ambient temperature, startup, power cycle, heat removal capability, loop capillary limit and recovery from a dry-out, low power operation, and long duration steady state operation. The neon CLHP demonstrated robust operation. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully by applying power to both the pump and evaporator without any pre-conditioning. It could adapt to changes in the pump power andor evaporator power, and reach a new steady state very quickly. The evaporator could remove heat loads between 0.25W and 4W. When the pump capillary limit was exceeded, the loop could resume its normal function by reducing the pump power. Steady state operations were demonstrated for up to 6 hours. The ability of the neon loop to cool large areas was therefore successfully verified.

  7. Direct Observation of Highly Ordered Dendrimer Soft Building Blocks over a Large Area.

    PubMed

    Kwon, Kiok; Ok, Jong Min; Kim, Yun Ho; Kim, Jong-Seon; Jung, Woo-Bin; Cho, Soo-Yeon; Jung, Hee-Tae

    2015-11-11

    Developing large-area, single domain of organic soft-building blocks such as block copolymers, colloids, and supramolecular materials is one of the most important issues in the materials science and nanotechnology. Owing to their small sizes, complex molecular architectures, and high mobility, supramolecular materials are not well-suited for building large area, single domain structures. In the described study, a single domain of supramolecular columnar dendrimers was created over large area. The columnar structures in these domains have smaller (4.5 nm) diameters, higher area densities (ca. 36 Tera-dots/in(2)) and larger domains (>0.1 × 0.1 mm(2)) than those of all existing BCP and colloidal assemblies. By simply annealing dendrimer thin films between two flat solid surfaces, single domains of hexagonal columnar structures are created over large macroscopic areas. Observations made in this effort should serve as the foundation for the design of new routes for bottom-up lithography based on supramolecular building blocks.

  8. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar.

    PubMed

    Swatantran, Anu; Tang, Hao; Barrett, Terence; DeCola, Phil; Dubayah, Ralph

    2016-01-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km(2)). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping. PMID:27329078

  9. A study on the fabrication of nanostructures with high aspect ratio and large area uniformity.

    PubMed

    Sun, Tangyou; Xut, Zhimou; Wang, Shuangbao; Zhao, Wenning; Wu, Xinghui; Liu, Sisi; Liu, Wen; Peng, Jing; Wang, Zhihao; Zhang, Xueming; He, Jian

    2013-03-01

    Nanoimprint lithography (NIL), as a promising next generation lithography method, has the advantages of high throughput, sub-10-nm feature and low cost. However, the requirements, such as the structure with high aspect ratio, large area uniformity, and pattern transfer on nonflat surface, have barely been satisfied at the same time. In this study, the authors present a novel fabrication process by introducing a three-mask-layer (TML) Soft UV NIL technique which proves to be a simple and effective method. The initial mold with low aspect ratio can guarantee the imprint uniformity on large area under a high pressure in NIL. Meanwhile, high aspect ratio structure can be easily obtained due to a high etching selectivity of SiO2 to resist in O2 plasma dry etching. Using the proposed technique to fabricate 40 nm gratings with the aspect ratio as high as 6 is proved successful. Uniform photonic crystal (PC) structures with micrometer scale nonflat steps are obtained on large area. The photoluminescence enhancements of the PC light-emitting diode (LED) fabricated by the proposed method to the one with conventional process and un-patterned LED are 1.6 fold and 2.2 fold, respectively. PMID:23755609

  10. A High-Flux, Flexible Membrane with Parylene-encapsulated Carbon Nanotubes

    SciTech Connect

    Park, H G; In, J; Kim, S; Fornasiero, F; Holt, J K; Grigoropoulos, C P; Noy, A; Bakajin, O

    2008-03-14

    We present fabrication and characterization of a membrane based on carbon nanotubes (CNTs) and parylene. Carbon nanotubes have shown orders of magnitude enhancement in gas and water permeability compared to estimates generated by conventional theories [1, 2]. Large area membranes that exhibit flux enhancement characteristics of carbon nanotubes may provide an economical solution to a variety of technologies including water desalination [3] and gas sequestration [4]. We report a novel method of making carbon nanotube-based, robust membranes with large areas. A vertically aligned dense carbon nanotube array is infiltrated with parylene. Parylene polymer creates a pinhole free transparent film by exhibiting high surface conformity and excellent crevice penetration. Using this moisture-, chemical- and solvent-resistant polymer creates carbon nanotube membranes that promise to exhibit high stability and biocompatibility. CNT membranes are formed by releasing a free-standing film that consists of parylene-infiltrated CNTs, followed by CNT uncapping on both sides of the composite material. Thus fabricated membranes show flexibility and ductility due to the parylene matrix material, as well as high permeability attributed to embedded carbon nanotubes. These membranes have a potential for applications that may require high flux, flexibility and durability.

  11. Conformable seal

    DOEpatents

    Neef, W.S.; Lambert, D.R.

    1982-08-10

    Sealing apparatus and method, comprising first and second surfaces or membranes, at least one of which surfaces is deformable, placed in proximity to one another. Urging means cause these surfaces to contact one another in a manner such that the deformable surface deforms to conform to the geometry of the other surface, thereby creating a seal. The seal is capable of undergoing multiple cycles of sealing and unsealing.

  12. Performance of Conformable Ablators in Aerothermal Environments

    NASA Technical Reports Server (NTRS)

    Thornton, J.; Fan, W.; Skokova, K.; Stackpoole, M.; Beck, R.; Chavez-Garcia, J.

    2012-01-01

    Conformable Phenolic Impregnated Carbon Ablator, a cousin of Phenolic Impregnated Carbon Ablator (PICA), was developed at NASA Ames Research Center as a lightweight thermal protection system under the Fundamental Aeronautics Program. PICA is made using a brittle carbon substrate, which has a very low strain to failure. Conformable PICA is made using a flexible carbon substrate, a felt in this case. The flexible felt significantly increases the strain to failure of the ablator. PICA is limited by its thermal mechanical properties. Future NASA missions will require heatshields that are more fracture resistant than PICA and, as a result, NASA Ames is working to improve PICAs performance by developing conformable PICA to meet these needs. Research efforts include tailoring the chemistry of conformable PICA with varying amounts of additives to enhance mechanical properties and testing them in aerothermal environments. This poster shows the performance of conformable PICA variants in arc jets tests. Some mechanical and thermal properties will also be presented.

  13. Laser interference lithography for large area patterning and the fabrication of functional nanostructures

    NASA Astrophysics Data System (ADS)

    Wathuthanthri, Ishan

    Nature-inspired phenomena such as the "moth eye" and "lotus leaf" effects have gained a lot of interest in recent years due to potential applications in a wide range of scientific and engineering disciplines. To practically achieve a majority of these biomimetic applications it is necessary to fabricate such nano-featured surfaces in a low-cost and high-throughput manner. To this end, this dissertation focuses on developing and using the Interference Lithography (IL) technologies to achieve large-area nanopatterning. IL is a parallel-type nanolithography technique that shares many of the advantages of other parallel-type techniques such as deep-UV photolithography while alleviating a majority of concerns such as cost and complexity. IL relies on the interference of two or more beams of light where the resulting interference fringes are generally recorded on a light sensitive polymeric material such as photoresist. In simple two-beam IL systems, the periodicity of the interference fringes is simply a function of wavelength and the angle of separation of the two beams, while the maximum coverage area is a constrained by the optical path and the exposed area. To this extent, in the design of interferometers for nanopatterning, the challenge remains in designing systems where a simple mechanism exists for varying the angle of separation of the interfering beams and in turn periodicity of the interference fringes while also enabling large-area exposures. To this end, the first half of this dissertation demonstrates three different IL systems (Lloyd-mirror, two-degree-of freedom Lloyd-mirror, and the tunable two-mirror systems) designed and established at Stevens capable of fast tuning of periodicities while also achieving wafer-scale (4") large-area nanopatterning. Using the large-area nanopatterns of photoresist, various pattern transfer techniques have also been investigated where the photoresist film is used as a template layer to transfer the large-area periodic

  14. Large-area perovskite nanowire arrays fabricated by large-scale roll-to-roll micro-gravure printing and doctor blading.

    PubMed

    Hu, Qiao; Wu, Han; Sun, Jia; Yan, Donghang; Gao, Yongli; Yang, Junliang

    2016-03-01

    Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ∼45%, temperature ∼28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays with great potential applications in flexible electronic and optoelectronic devices. PMID:26883938

  15. Large Area 2D and 3D Colloidal Photonic Crystals Fabricated by a Roll-to-Roll Langmuir-Blodgett Method.

    PubMed

    Parchine, Mikhail; McGrath, Joe; Bardosova, Maria; Pemble, Martyn E

    2016-06-14

    We present our results on the fabrication of large area colloidal photonic crystals on flexible poly(ethylene terephthalate) (PET) film using a roll-to-roll Langmuir-Blodgett technique. Two-dimensional (2D) and three-dimensional (3D) colloidal photonic crystals from silica nanospheres (250 and 550 nm diameter) with a total area of up to 340 cm(2) have been fabricated in a continuous manner compatible with high volume manufacturing. In addition, the antireflective properties and structural integrity of the films have been enhanced via the use of a second roll-to-roll process, employing a slot-die coating of an optical adhesive over the photonic crystal films. Scanning electron microscopy images, atomic force microscopy images, and UV-vis optical transmission and reflection spectra of the fabricated photonic crystals are analyzed. This analysis confirms the high quality of the 2D and 3D photonic crystals fabricated by the roll-to-roll LB technique. Potential device applications of the large area 2D and 3D colloidal photonic crystals on flexible PET film are briefly reviewed. PMID:27218474

  16. Large Area 2D and 3D Colloidal Photonic Crystals Fabricated by a Roll-to-Roll Langmuir-Blodgett Method.

    PubMed

    Parchine, Mikhail; McGrath, Joe; Bardosova, Maria; Pemble, Martyn E

    2016-06-14

    We present our results on the fabrication of large area colloidal photonic crystals on flexible poly(ethylene terephthalate) (PET) film using a roll-to-roll Langmuir-Blodgett technique. Two-dimensional (2D) and three-dimensional (3D) colloidal photonic crystals from silica nanospheres (250 and 550 nm diameter) with a total area of up to 340 cm(2) have been fabricated in a continuous manner compatible with high volume manufacturing. In addition, the antireflective properties and structural integrity of the films have been enhanced via the use of a second roll-to-roll process, employing a slot-die coating of an optical adhesive over the photonic crystal films. Scanning electron microscopy images, atomic force microscopy images, and UV-vis optical transmission and reflection spectra of the fabricated photonic crystals are analyzed. This analysis confirms the high quality of the 2D and 3D photonic crystals fabricated by the roll-to-roll LB technique. Potential device applications of the large area 2D and 3D colloidal photonic crystals on flexible PET film are briefly reviewed.

  17. Potential energy hypersurface and molecular flexibility

    NASA Astrophysics Data System (ADS)

    Koča, Jaroslav

    1993-02-01

    The molecular flexibility phenomenon is discussed from the conformational potential energy(hyper) surface (PES) point of view. Flexibility is considered as a product of three terms: thermodynamic, kinetic and geometrical. Several expressions characterizing absolute and relative molecular flexibility are introduced, depending on a subspace studied of the entire conformational space, energy level E of PES as well as absolute temperature. Results obtained by programs DAISY, CICADA and PANIC in conjunction with molecular mechanics program MMX for flexibility analysis of isopentane, 2,2-dimethylpentane and isohexane molecules are introduced.

  18. Carbon Nanotube Flexible and Stretchable Electronics.

    PubMed

    Cai, Le; Wang, Chuan

    2015-12-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail. PMID:26264684

  19. Carbon Nanotube Flexible and Stretchable Electronics.

    PubMed

    Cai, Le; Wang, Chuan

    2015-12-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail.

  20. Carbon Nanotube Flexible and Stretchable Electronics

    NASA Astrophysics Data System (ADS)

    Cai, Le; Wang, Chuan

    2015-08-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail.

  1. Flight Qualification And Production Results With Large Area Space Solar Cells And Panel Assembly

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.; Hanley, James; Jun, Bogim; Bardfield, Rina; Stone, Beth

    2011-10-01

    Spectrolab's product roadmap provides improvement in product performance in parallel with continuous cost reduction to maintain competitive standing in our industry. Product performance improvement is achieved by developing higher efficiency solar cells (e.g. 29.5% XTJ and 33% IMM cells).Reduced product cost is achieved historically through a variety of means including yield improvements, direct material cost reductions, process changes, and most recently, a transition to large area cell configurations (e.g. "LEONE" at 59.65 cm2). Spectrolab has successfully completed the qualification of its latest triple junction space solar cell, the 29.5% 2 XTJ (26.62 cm ), per AIAA-S-111-2005 - augmented by additional Spectrolab testing. Large area LEONE UTJ and XTJ cells (59.65 cm2 from 100 mm diameter germanium wafer) have also been qualified. Use of these large area cells has resulted in the reduction of solar panel cost, add-on mass and manufacturing cycle time for programs. This evolution to larger area cells is the result of a strategic cost reduction effort initiated in 2006; the first step of which was to manufacture the largest possible cells (LEONE) using the 100 mm germanium (Ge) wafer. In flight production since 2007, the LEONE UTJ cell has now completed rigorous qualification testing to 15,549 GEO (Geosynchronous orbit) and 66,060 LEO (Low Earth Orbit) thermal cycles. Over 53,000 LEONE UTJ cells, including more than 27,000 cells on panels delivered to flight programs, have been produced to date. The on-orbit performance of the LEONE UTJ cells is nominal. Finally, progress on the second step of our strategic cost reduction effort towards larger cells and less piece part handling is presented. This effort involves the establishment of a 150 mm Ge -based manufacturing infrastructure.

  2. Testing of a Helium Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin Lee

    2015-01-01

    Future NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components in the 3K temperature range. A copper plate with attached electrical heters was used to simulate the heat source, and heat was collected by the CLHP evaporator and transferred to the cryocooler for ultimate heat rejection. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully without pre-conditioning by simply applying power to both the capillary pump and the evaporator plate. It could adapt to rapid changes in the heat load, and reach a new steady state very quickly. Heat removal between 10mW and 140mW was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.

  3. Testing of a Helium Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin

    2016-01-01

    Future NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components in the 3K temperature range. A copper plate with attached electrical heaters was used to simulate the heat source, and heat was collected by the CLHP evaporator and transferred to the cryocooler for ultimate heat rejection. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully without pre-conditioning by simply applying power to both the capillary pump and the evaporator plate. It could adapt to rapid changes in the heat load, and reach a new steady state very quickly. Heat removal between 10mW and 140mW was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.

  4. Large-area CMOS solid-state photomultipliers and recent developments

    NASA Astrophysics Data System (ADS)

    Johnson, Erik B.; Stapels, Christopher J.; Jie Chen, Xiao; Augustine, Frank L.; Christian, James F.

    2011-10-01

    The CMOS solid-state photomultiplier (SSPM) is an array of Geiger avalanche photodiodes (GPD) read out in parallel. These devices are not susceptible to magnetic fields, less expensive to fabricate than many other photodetector technologies, compact, and allow for on-chip integration of signal processing circuits. A number of nuclear detection applications require detector sizes on the order of 1 cm. Standard silicon fabrication technology limits the size of the SSPM die, and tiling of the silicon die can result in large-area devices but results in dead space between die for bonding purposes. Radiation Monitoring Devices (RMD) has fabricated 1×1 cm SSPM arrays on a single die. The size of these devices is large enough to provide an alternative detector for scintillation detector applications compared to photomultiplier tubes. Although the size increases the dark noise, we will demonstrate that the large-area SSPM can provide a PMT-like response for 22Na gamma rays using an LYSO crystal. Each of the noise terms associated with the large-area SSPM is discussed, quantifying the cross talk and after pulse multipliers, which are scaling factors to the gain to account for the additional output charge from the SSPM. The excess noise factor associated with cross talk and after pulsing has a linear dependence on the multiplier term. The signal and noise terms have been compiled to provide the best operating voltage of roughly 6 V above breakdown for a 1×1 cm CMOS SSPM to be operated with a short integration time (<10 ns) and at 0 °C.

  5. Simple room-temperature preparation of high-yield large-area graphene oxide

    PubMed Central

    Huang, NM; Lim, HN; Chia, CH; Yarmo, MA; Muhamad, MR

    2011-01-01

    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer’s method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm2, respectively. The simplified Hummer’s method provides a facile approach for the preparation of large-area GO. PMID:22267928

  6. Nanosphere lithography based technique for fabrication of large area well ordered metal particle arrays

    NASA Astrophysics Data System (ADS)

    Barcelo, Steven J.; Lam, Si-Ty; Gibson, Gary A.; Sheng, Xia; Henze, Dick

    2012-03-01

    Nanosphere lithography is an effective technique for high throughput fabrication of well-ordered patterns, but expanding the method to large area coverage of nanoparticles less than 300 nm in diameter while maintaining good order has proven challenging. Here we demonstrate a nanosphere lithography based technique for fabricating large area, wellordered arrays of hemispherical metal particles which pushes the limits of these size constraints. First, large area monolayers of polystyrene (PS) nanospheres are assembled at an air-water interface and then transferred to a submerged substrate. The submerged substrate is supported at a 10° angle so that the water draining speed can be used to control the transfer rate, which is essential for hydrophobic substrates such as the polymer-coated glass used in our work. A double liftoff procedure was used to transfer the PS pattern to a silver particle array on an arbitrary substrate, achieving tunable control over the final metal particle diameter and spacing in the range of 50-150 nm and 100-200 nm, respectively. Additional control over particle shape and diameter can be obtained by modifying the substrate surface energy. For example, depositing silver on ITO-coated glass rather than a more hydrophilic clean glass substrate leads to a more hemispherical particle shape and a diameter reduction of 20%. Peak wavelength-selective reflection greater than 70% and total extinction greater than 90% were measured. The intensity, position and bandwidth of the main plasmon resonance of the arrays were shown to have minimal angle dependence up to at least 30° off normal.

  7. Evaluation of large area crop estimation techniques using LANDSAT and ground-derived data. [Missouri

    NASA Technical Reports Server (NTRS)

    Amis, M. L.; Lennington, R. K.; Martin, M. V.; Mcguire, W. G.; Shen, S. S. (Principal Investigator)

    1981-01-01

    The results of the Domestic Crops and Land Cover Classification and Clustering study on large area crop estimation using LANDSAT and ground truth data are reported. The current crop area estimation approach of the Economics and Statistics Service of the U.S. Department of Agriculture was evaluated in terms of the factors that are likely to influence the bias and variance of the estimator. Also, alternative procedures involving replacements for the clustering algorithm, the classifier, or the regression model used in the original U.S. Department of Agriculture procedures were investigated.

  8. Final Scientific/Technical Report Development of Large-Area Photo-Detectors

    SciTech Connect

    Frisch, Henry J.

    2013-07-15

    This proposal requested ADR funds for two years to make measurements and detector proto-types in the context of planning a program in conjunction with Argonne National Laboratory to develop very large-area planar photodetectors. The proposed detectors have integrated transmission-line readout and sampling electronics able to achieve timing and position resolutions in the range of 1-50 psec and 1-10 mm, respectively. The capability for very precise time measurements is inherent in the design, and provides a third coordinate, orthogonal to the two in the plane, for the point of origin of photons or charged particles, allowing tomographic reconstruction in 3-dimensions inside a volume.

  9. Design and Characteristics of the Anticoincidence Detector for the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Moiseev, A. A.; Hartman, R. C.; Johnson, T. E.; Ormes, J. F.; Thompson, D. J.

    2005-01-01

    The Anti-Coincidence Detector (ACD) is the outermost detector layer in the GLAST Large Area Telescope (LAT), surrounding the top and sides of the tracker. The purpose of the ACD is to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly charged relativistic particles, but must also have low sensitivity to backsplash particles. These are products of high- energy interactions in the LAT calorimeter. They can cause a veto signal in the ACD, resulting in loss of good gamma-ray events.

  10. Approaching total absorption at near infrared in a large area monolayer graphene by critical coupling

    SciTech Connect

    Liu, Yonghao; Chadha, Arvinder; Zhao, Deyin; Shuai, Yichen; Menon, Laxmy; Yang, Hongjun; Zhou, Weidong; Piper, Jessica R.; Fan, Shanhui; Jia, Yichen; Xia, Fengnian; Ma, Zhenqiang

    2014-11-03

    We demonstrate experimentally close to total absorption in monolayer graphene based on critical coupling with guided resonances in transfer printed photonic crystal Fano resonance filters at near infrared. Measured peak absorptions of 35% and 85% were obtained from cavity coupled monolayer graphene for the structures without and with back reflectors, respectively. These measured values agree very well with the theoretical values predicted with the coupled mode theory based critical coupling design. Such strong light-matter interactions can lead to extremely compact and high performance photonic devices based on large area monolayer graphene and other two–dimensional materials.

  11. Microfabrication of large-area circular high-stress silicon nitride membranes for optomechanical applications

    NASA Astrophysics Data System (ADS)

    Serra, E.; Bawaj, M.; Borrielli, A.; Di Giuseppe, G.; Forte, S.; Kralj, N.; Malossi, N.; Marconi, L.; Marin, F.; Marino, F.; Morana, B.; Natali, R.; Pandraud, G.; Pontin, A.; Prodi, G. A.; Rossi, M.; Sarro, P. M.; Vitali, D.; Bonaldi, M.

    2016-06-01

    In view of the integration of membrane resonators with more complex MEMS structures, we developed a general fabrication procedure for circular shape SiNx membranes using Deep Reactive Ion Etching (DRIE). Large area and high-stress SiNx membranes were fabricated and used as optomechanical resonators in a Michelson interferometer, where Q values up to 1.3 × 106 were measured at cryogenic temperatures, and in a Fabry-Pérot cavity, where an optical finesse up to 50000 has been observed.

  12. Indirect searches for dark matter with the Fermi large area telescope

    DOE PAGESBeta

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce γ rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for γ-ray spectral lines and γ-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  13. Electrochemical preparation of metal microstructures on large areas of etched ion track membranes

    NASA Astrophysics Data System (ADS)

    Dobrev, D.; Vetter, J.; Angert, N.

    1999-01-01

    A microgalvanic method for metal filling of etched ion tracks in organic foils on large areas is described. The method and the used galvanic cell permit the deposition of stable standing individual metal whiskers with high aspect ratio and a density of 10 5-10 8 per cm 2 on an area of 12.5 cm 2. The method was verified with copper and it is suitable also for various other metals. It can be applied for the replication of etched ion tracks and for the fabrication of microstructures containing large numbers of individual metal whiskers.

  14. Beta Cage: A New, Large-Area Multi-Wire Screening Detector For Surface Beta Contamination

    SciTech Connect

    Shutt, T.; Schnee, R.W.; Dahl, C.E.; Viveiros, L. de; Gaitskell, R.J.

    2005-09-08

    We report on a design study for a new, dedicated, low-radioactive-background screening detector for low-energy beta-emitting contamination on surfaces. The detector, a large-area gaseous detector with multi-wire proportional readout, has sufficient sensitivity to screen materials at the level needed for the proposed SuperCDMS 1 ton dark matter experiment. Such capability does not currently exist. This detector would have additional applications in low-radioactive-background physics experiments, and radioactive trace analysis, such as 14C dating.

  15. Large area low cost processing for CIS photovoltaics. Final technical report

    SciTech Connect

    B. Basol; G. Norsworthy; C. Leidholm; A. Halani; R. Roe; V. Kapur

    1999-07-22

    An ink coating method was developed for CIS absorber deposition. The technique involves four processing steps: (1) preparation of a Cu-In alloy powder, (2) preparation of an ink using this powder, (3) deposition of the ink on a substrate in the form of a precursor layer, and (4) selenization to convert the Cu-In precursor into a fused CIS film. Absorbers grown by this low-cost, large-area method were used in the fabrication of 10.5% efficient solar cells.

  16. The Fermi Large Area Telescope: Highlights from the first year on orbit

    SciTech Connect

    Raino, S.

    2010-03-26

    Since its launch from Cape Canaveral on June 11, 2008, the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope has been performing a survey of the high-energy astrophysical phenomena, including pulsars, black holes and active galactic nuclei; gamma-ray bursts; the origin of cosmic rays and supernova remnants and searches for new phenomena such as supersymmetric dark-matter annihilation. In this contribution I report on the performance of the LAT and on the highlight results achieved in its first year of observations.

  17. Detection of localized hot electrons in low-pressure large-area microwave discharges

    NASA Astrophysics Data System (ADS)

    Terebessy, Tibor; Kando, Masashi; Kudela, Jozef

    2000-10-01

    A localized hot-electron region was observed in low-pressure (<3 mTorr) large-area microwave discharges. The region appears in the vicinity of the waveguiding plasma-dielectric interface in the place of critical plasma density. The existence of localized hot electrons is explained on the basis of transit time heating in the resonantly enhanced electric field. The phenomenon provides experimental evidence that the plasma resonance region plays an active role in heating mechanism in low-pressure microwave discharges.

  18. Coatings for large-area low-cost solar concentrators and reflectors

    NASA Astrophysics Data System (ADS)

    Martin, Peter M.; Affinito, John D.; Gross, Mark E.; Bennett, Wendy D.

    1994-09-01

    Large-optics coating facilities and processes at Pacific Northwest Laboratory (PNL) that were used to develop large-area high-performance laser mirrors for SDIO are now being used to fabricate a variety of optical components for commercial clients, and for novel applications for other DoD clients. Emphasis of this work is on technology transfer of low-cost coating processes and equipment to private clients. Much of the technology transfer is being accomplished through the CRADA (Cooperative Research and Development Agreement) process funded by the Department of Energy (DOE).

  19. Large area TES spiderweb bolometer for multi-mode cavity microwave detect

    NASA Astrophysics Data System (ADS)

    Biasotti, M.; Bagliani, D.; Ceriale, V.; Corsini, D.; De Bernardis, P.; Gatti, F.; Gualtieri, R.; Lamagna, L.; Masi, S.; Pizzigoni, G.; Schillaci, A.

    2014-07-01

    Large area spiderweb bolometers of 8 mm diameter and a mesh size of 250 μm are fabricated in order to couple with approximately the first 20 modes of a multimode EM cavity at about 140 GHz. The sensor is a Ti/Au/Ti 3 layer TES with Tc tuned in the 330-380 mK and 2 mK transition width. We describe the detector design and the fabrication process, early TES electro-thermal measurements. We also report optical coupling measurement and show the multimode coupling.

  20. Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

    SciTech Connect

    Saraf, Laxmikant V.; Britt, David W.

    2011-09-14

    We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

  1. The Silicon Tracker Readout Electronics of the Gamma-ray Large Area Space Telescope

    SciTech Connect

    Baldini, Luca; Brez, Alessandro; Himel, Thomas; Hirayama, Masaharu; Johnson, R.P.; Kroeger, Wilko; Latronico, Luca; Minuti, Massimo; Nelson, David; Rando, Riccardo; Sadrozinski, H.F.-W.; Sgro, Carmelo; Spandre, Gloria; Spencer, E.N.; Sugizaki, Mutsumi; Tajima, Hiro; Cohen-Tanugi, Johann; Ziegler, Marcus; /Pisa U. /INFN, Pisa /SLAC /Maryland U. /UC, Santa Cruz /Padua U. /INFN, Padua

    2006-02-27

    A unique electronics system has been built and tested for reading signals from the silicon-strip detectors of the Gamma-ray Large Area Space Telescope mission. The system amplifies and processes signals from 884,736 36-cm strips using only 160 W of power, and it achieves close to 100% detection efficiency with noise occupancy sufficiently low to allow it to self trigger. The design of the readout system is described, and results are presented from ground-based testing of the completed detector system.

  2. Long life electrodes for large-area x-ray generators

    NASA Technical Reports Server (NTRS)

    Rothe, Dietmar E. (Inventor)

    1991-01-01

    This invention is directed to rugged, reliable, and long-life electrodes for use in large-area, high-current-density electron gun and x-ray generators which are employed as contamination-free preionizers for high-energy pulsed gas lasers. The electron source at the cathode is a corona plasma formed at the interface between a conductor, or semiconductor, and a high-permittivity dielectric. Detailed descriptions are provided of a reliable cold plasma cathode, as well as an efficient liquid-cooled electron beam target (anode) and x-ray generator which concentrates the x-ray flux in the direction of an x-ray window.

  3. Indirect searches for dark matter with the Fermi large area telescope

    SciTech Connect

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce γ rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for γ-ray spectral lines and γ-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  4. Status of GLAST, the Gamma-ray Large-area Space Telescope

    SciTech Connect

    Rochester, L.; /SLAC

    2005-12-14

    GLAST is a satellite-based observatory consisting of the Large-Area Telescope (LAT), a modular 4 x 4-tower pair-conversion telescope with a field-of-view greater than 2 steradians, capable of measuring gamma-ray energies in the range 20 MeV to 300 GeV, and the GLAST Burst Monitor (GBM), a set of NaI and BGO detectors covering 8 steradians and sensitive to photons with energies between 10 keV and 25 MeV, allowing for correlative observations of transient events. The observatory is currently being constructed and is scheduled to be launched in August 2007.

  5. Large-Area Atom Interferometry with Frequency-Swept Raman Adiabatic Passage.

    PubMed

    Kotru, Krish; Butts, David L; Kinast, Joseph M; Stoner, Richard E

    2015-09-01

    We demonstrate light-pulse atom interferometry with large-momentum-transfer atom optics based on stimulated Raman transitions and frequency-swept adiabatic rapid passage. Our atom optics have produced momentum splittings of up to 30 photon recoil momenta in an acceleration-sensitive interferometer for laser cooled atoms. We experimentally verify the enhancement of phase shift per unit acceleration and characterize interferometer contrast loss. By forgoing evaporative cooling and velocity selection, this method lowers the atom shot-noise-limited measurement uncertainty and enables large-area atom interferometry at higher data rates.

  6. Measuring the mechanical properties of molecular conformers

    NASA Astrophysics Data System (ADS)

    Jarvis, S. P.; Taylor, S.; Baran, J. D.; Champness, N. R.; Larsson, J. A.; Moriarty, P.

    2015-09-01

    Scanning probe-actuated single molecule manipulation has proven to be an exceptionally powerful tool for the systematic atomic-scale interrogation of molecular adsorbates. To date, however, the extent to which molecular conformation affects the force required to push or pull a single molecule has not been explored. Here we probe the mechanochemical response of two tetra(4-bromophenyl)porphyrin conformers using non-contact atomic force microscopy where we find a large difference between the lateral forces required for manipulation. Remarkably, despite sharing very similar adsorption characteristics, variations in the potential energy surface are capable of prohibiting probe-induced positioning of one conformer, while simultaneously permitting manipulation of the alternative conformational form. Our results are interpreted in the context of dispersion-corrected density functional theory calculations which reveal significant differences in the diffusion barriers for each conformer. These results demonstrate that conformational variation significantly modifies the mechanical response of even simple porpyhrins, potentially affecting many other flexible molecules.

  7. Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Engineering Model: Overview

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Godfrey, G.; Williams, S. M.; Grove, J. E.; Mizuno, T.; Sadrozinski, H. F.-W.; Kamae, T.; Ampe, J.; Briber, Stuart; Dann, James; White, Nicholas E. (Technical Monitor)

    2001-01-01

    The Gamma Ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) is a pair-production high-energy (greater than 20 MeV) gamma-ray telescope being built by an international partnership of astrophysicists and particle physicists for a satellite launch in 2006, designed to study a wide variety of high-energy astrophysical phenomena. As part of the development effort, the collaboration has built a Balloon Flight Engineering Model (BFEM) for flight on a high-altitude scientific balloon. The BFEM is approximately the size of one of the 16 GLAST-LAT towers and contains all the components of the full instrument: plastic scintillator anticoincidence system (ACD), high-Z foil/Si strip pair-conversion tracker (TKR), CsI hodoscopic calorimeter (CAL), triggering and data acquisition electronics (DAQ), commanding system, power distribution, telemetry, real-time data display, and ground data processing system. The principal goal of the balloon flight was to demonstrate the performance of this instrument configuration under conditions similar to those expected in orbit. Results from a balloon flight from Palestine, Texas, on August 4, 2001, show that the BFEM successfully obtained gamma-ray data in this high-background environment.

  8. Synthesis and Characterization of Large-Area Graphene Directly CVD-Grown on h-BN

    NASA Astrophysics Data System (ADS)

    Kim, Minwoo; Song, Young; Wang, Min; Jang, Seong-Kyu; Lee, Sungjoo; Jang, Won-Jun; Kahng, Se-Jong; Graphene synthesis Collaboration; Characterization Collaboration

    2013-03-01

    As an ideal substrate for graphene, hexagonal boron nitride (h-BN) has been utilized and studied extensively by transfer technique, which still has a high chance to have impurities at the graphene/h-BN interface. Here we report direct CVD growth of graphene on large area h-BN film. AFM and Raman spectroscopy measurements show that there is only one monolayer of graphene, and whose unperturbed electronic structures are also confirmed by electron transport measurements and scanning tunneling spectroscopy. High resolution TEM images for cross-section taken before and after transferring graphene/h-BN on to SiO2 indicate this CVD-grown hybrid structure is robust enough. Based on this new method, high quality and large area graphene on h-BN film with a clean interface can be synthesized for the application of electronic devices, and can fill the missing steps to grow fully CVD-grown super-structure of graphene and h-BN. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (Grant Numbers: 2009-0083540, 2012R1A1A2020089 and 2012R1A1A1041416).

  9. GLAST LARGE AREA TELESCOPE: DAILY SURVEY OF HIGH-ENERGY SKY

    SciTech Connect

    Kamae, T

    2003-12-12

    GLAST Large Area Telescope was proposed to NASA in 1999 as follow-up of EGRET on-board Compton Gamma-Ray Observatory by an international collaboration. The proposal has been approved as a part of the GLAST observatory mission in its capability to explore w die range of astrophysics with 5-40 times higher sensitivity and extended energy coverage (20 MeV to 300 GeV) than EGRET. The instrument consists of 16 towers of e{sup +}e{sup -} pair tracker, 16 blocks of segmented electro-magnetic calorimeter, and a st of anti-coincidence plastic scintillator tiles covering the tracker towers. It will have 5-10 times larger on-axis effective area, 6 times wider field-of-view (FOV), and up to 5 times better angular resolution when compared with EGRET. The Large Area Telescope will cover about 40% of the sky above the Earth's horizon in its FOV at any given time and will scan nearly the entire Universe every orbit ({approx} 90min): about 20% of Gamma-Ray Bursts will be observed from the onset of the bursts to the initial after-glow phase; all longer-lasting transients and variabilities will be detected daily at the improved sensitivity.

  10. The Gamma-ray Large Area Space Telescope and Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    McEnery, Julie; Ritz, Steve

    2006-01-01

    The Gamma-ray Large Area Telescope (GLAST) is a satellite-based observatory to study the high energy gamma-ray sky. The main instrument on GLAST, the Large Area Telescope (LAT) is a pair-conversion telescope that will survey the sky from 20 MeV to greater than 300 GeV. With the GLAST launch in 2007, the LAT will open a new and important window on a wide variety of high energy phenomena, including supermassive black holes and active galactic nuclei, gamma-ray bursts, supernova remnants and cosmic ray acceleration and dark matter. A second instrument, the GLAST Burst Monitor (GBM), greatly enhances GLAST s capability to study GRB by providing important spectral and timing information in the 10 keV to 30 MeV range. We describe how the instruments, spacecraft and ground system work together to provide observations of gamma-ray bursts from 8 keV - 300 GeV and to provide rapid notification of bursts to the wider gamma-ray burst community.

  11. MILDOS-AREA: An enhanced version of MILDOS for large-area sources

    SciTech Connect

    Yuan, Y.C.; Wang, J.H.C.; Zielen, A.

    1989-06-01

    The MILDOS-AREA computer code is a modified version of the MILDOS code, which estimates the radiological impacts of airborne emissions from uranium mining and milling facilities or any other large-area source involving emissions of radioisotopes of the uranium-238 series. MILDOS-AREA is designed for execution on personal computers. The modifications incorporated in the MILDOS-AREA code provide enhanced capabilities for calculating doses from large-area sources and update dosimetry calculations. The major revision from the original MILDOS code is the treatment of atmospheric dispersion from area sources: MILDOS-AREA substitutes a finite element integration approach for the virtual-point method (the algorithm used in the original MILDOS code) when specified by the user. Other revisions include the option of using Martin-Tickvart dispersion coefficients in place of Briggs coefficients for a given source, consideration of plume reflection, and updated internal dosimetry calculations based on the most recent recommendations of the International Commission on Radiation Protection and the age-specific dose calculation methodology developed by Oak Ridge National Laboratory. This report also discusses changes in computer code structure incorporated into MILDOS-AREA, summarizes data input requirements, and provides instructions for installing and using the program on personal computers. 15 refs., 9 figs., 26 tabs.

  12. Thermal response of large area high temperature superconducting YBaCuO infrared bolometer

    NASA Technical Reports Server (NTRS)

    Khalil, Ali E.

    1990-01-01

    Thermal analysis of large area high temperature superconducting infrared detector operating in the equilibrium mode (bolometer) was performed. An expression for the temperature coefficient beta=1/R(dR/dT) in terms of the thermal conductance and the thermal time constant of the detector were derived. A superconducting transition edge bolometer is a thermistor consisting of a thin film superconducting YBaCuO evaporated into a suitable thermally isolated substrate. The operating temperature of the bolometer is maintained close to the midpoint of the superconducting transition region where the resistance R has a maximum dynamic range. A detector with a strip configuration was analyzed and an expression for the temperature rise (delta T) above the ambient due to a uniform illumination with a source of power density P(sub i) was calculated. An expression for the thermal responsivity of the detector was derived using the thermal diffusion analysis with appropriate boundary conditions. It was found that the thermal responsibility depends upon the spatial modulation frequency and the angular frequency of the incoming radiation. The problem of the thermal cross talk between different detector elements was addressed. In the case of monolithic HTS detector array with a row of square elements of dimensions 2a and CCD or CID readout electronics the thermal spread function was derived for different spacing between elements. This analysis can be critical for future design and applications of large area focal plane arrays as broad band optical detectors made of granular thin films HTS YBaCuO.

  13. Large area laser surface micro/nanopatterning by contact microsphere lens arrays

    NASA Astrophysics Data System (ADS)

    Sedao, X.; Derrien, T. J.-Y.; Romer, G. R. B. E.; Pathiraj, B.; Huis in `t Veld, A. J.

    2013-06-01

    Laser surface micro/nanopatterning by particle lens arrays is a well-known technique. Enhanced optical fields can be achieved on a substrate when a laser beam passes through a self-assembled monolayer of silica microspheres placed on the substrate. This enhanced optical field is responsible for ablative material removal from the substrate resulting in a patterned surface. Because of the laser ablation, the microspheres are often ejected from the substrate during laser irradiation. This is a major issue impeding this technique to be used for large area texturing. We explored the possibility to retain the spheres on the substrate surface during laser irradiation. A picosecond laser system (wavelength of 515 nm, pulse duration 6.7 ps, repetition rate 400 kHz) was employed to write patterns through the lens array on a silicon substrate. In this experimental study, the pulse energy was found to be a key factor to realize surface patterning and retain the spheres during the process. When the laser pulse energy is set within the process window, the microspheres stay on the substrate during and after laser irradiation. Periodic patterns of nanoholes can be textured on the substrate surface. The spacing between the nanoholes is determined by the diameter of the microspheres. The depth of the nanoholes varies, depending on the number of laser pulses applied and pulse energy. Large area texturing can be made using overlapping pulses obtained through laser beam scanning.

  14. In situ catalytic growth of large-area multilayered graphene/MoS2 heterostructures

    PubMed Central

    Fu, Wei; Du, Fei-Hu; Su, Juan; Li, Xin-Hao; Wei, Xiao; Ye, Tian-Nan; Wang, Kai-Xue; Chen, Jie-Sheng

    2014-01-01

    Stacking various two-dimensional atomic crystals on top of each other is a feasible approach to create unique multilayered heterostructures with desired properties. Herein for the first time, we present a controlled preparation of large-area graphene/MoS2 heterostructures via a simple heating procedure on Mo-oleate complex coated sodium sulfate under N2 atmosphere. Through a direct in situ catalytic reaction, graphene layer has been uniformly grown on the MoS2 film formed by the reaction of Mo species with S pecies, which is from the carbothermal reduction of sodium sulfate. Due to the excellent graphene “painting” on MoS2 atomic layers, the significantly shortened lithium ion diffusion distance and the markedly enhanced electronic conductivity, these multilayered graphene/MoS2 heterostructures exhibit high specific capacity, unprecedented rate performance and outstanding cycling stability, especially at a high current density, when used as an anode material for lithium batteries. This work provides a simple but efficient route for the controlled fabrication of large-area multilayered graphene/metal sulfide heterostructures with promising applications in battery manufacture, electronics or catalysis. PMID:24728289

  15. A large-area nanoscale gold hemisphere pattern as a nanoelectrode array.

    PubMed

    Li, Huaqing; Wu, Nianqiang

    2008-07-01

    Two-dimensional (2D) nanostructure patterns have extensive applications in photonic devices, nanoelectronics, electrochemical devices, biosensors, catalysts and high-density magnetic recording devices. It remains a challenge to develop low-cost, high-throughput, high-resolution techniques for the fabrication of large-area (wafer-scale) 2D nanostructure array patterns with controlled feature size, shape and pitch. The present work has demonstrated a low-cost, high-throughput, high-resolution approach for the fabrication of large-area, high-quality nanostructure array patterns by nanosphere lithography combined with electroplating. The gold hemisphere array pattern obtained is capable of functioning as a nanoelectrode array (NEA) in which the gold hemispheres act as individual electrodes that are separated with an insulating polypyrrole (PPY) film. Cyclic voltammetry measurement has shown a sigmoid-shaped voltammogram, which is characteristic of electrochemical characteristics of a nanoelectrode array. NEAs are expected to find extensive applications in fundamental electrochemistry studies and electrochemical devices.

  16. Widefield TSCSPC-systems with large-area-detectors: application in simultaneous multi-channel-FLIM

    NASA Astrophysics Data System (ADS)

    Stepanov, Sergei; Bakhlanov, Sergei; Drobchenko, Evgeny; Eckert, Hann-Jörg; Kemnitz, Klaus

    2010-11-01

    Novel proximity-type Time- and Space-Correlated Single Photon Counting (TSCSPC) crossed-delay-line (DL)- and multi-anode (MA)-systems of outstanding performance and homogeneity were developed, using large-area detector heads of 25 and 40 mm diameter. Instrument response functions IRF(space) = (60 +/- 5) μm FWHM and IRF(time) = (28 +/- 3) ps FWHM were achieved over the full 12 cm2 area of the detector. Deadtime at throughput of 105 cps is 10% for "high-resolution" system and 5% in the "video"-system at 106 cps, at slightly reduced time- and space resolution. A fluorescence lifetime of (3.5 +/- 1) ps can be recovered from multi-exponential dynamics of a single living cyanobacterium (Acaryochloris marina). The present large-area detectors are particularly useful in simultaneous multichannel applications, such as 2-colour anisotropy or 4-colour lifetime imaging, utilizing dual- or quad-view image splitters. The long-term stability, low- excitation-intensity (< 100 mW/cm2) widefield systems enable minimal-invasive observation, without significant bleaching or photodynamic reactions, thus allowing long-period observation of up to several hours in living cells.

  17. Large area graphene growth on 6H-SiC(0001)

    NASA Astrophysics Data System (ADS)

    Johansson, L. I.; Virojanadara, C.; Syväjärvi, M.; Yakimova, R.; Zakharov, A. A.; Balasubramanian, T.

    2009-03-01

    Large area graphene growth on commercial Si-face on-axis 6H-SiC(0001) is demonstrated in this work. Samples were produced in a prototype of an inductively heated furnace. The growth was carried out in strongly isothermal conditions at a temperature of 2000 C and at an ambient argon pressure of 1 atm. The quality and thickness of the graphene layers grown, using this ex situ method, were investigated using PES, ARPES), LEED as well as LEEM, PEEM micro-LEED and micro-PES at specifically defined small areas. Our results show that single layer graphene is formed over quite large areas on the sample but that two different domains can exist on some parts. A comparison with an in situ graphene sample, prepared by resistive heating to 1275 C, was made. The results then obtained were similar to earlier findings [1-2] and showed that the size of the graphene flakes were very small compared to those obtained on the samples prepared with our ex situ method. [3pt] [1]. T. Ohta, F. El Gabaly, A. Bostwick, J.L. McChesney, K.V. Emtsev, A.K. Schmid, Th. Seyller, K. Horn, E. Rotenberg, New. J. Phys. 10 023034 (2008).[0pt] [2]. J.B. Hannon and R. M. Tromp, Phys. Rev. B 77 241404 (2008).

  18. Development of Front-End Electronics for Large Area Solid-State Neutron Detector Arrays

    NASA Astrophysics Data System (ADS)

    English, Erik

    Solid-state neutron detectors represent a potential replacement technology for Helium-3 gas filled tubes used for detection of special nuclear materials. When scaling these detectors to very large areas the design of the associated electronics becomes critical to overall detection efficiency. This thesis explores the implementation of low noise readout electronics optimized for large area semiconductor neutron detector arrays. The readout system consists of a charge sensitive preamplifier, pulse shaper, and fast threshold crossing discriminator. Three different designs have been implemented, two of which are built using discrete parts on a printed circuit board while the third has been fabricated using the IBM 0.13microm CMOS process. Additionally, a novel preamplifier topology, utilizing a capacitance canceling input stage, is presented. Experimental results show that the utilization of a capacitance canceling stage has the capability to lower preamplifier noise by up to 15%. Finally, the CMOS implementation possesses the highest reported performance, in terms of noise and power, for high capacitance detectors to date.

  19. Large-area patterned substrates for micromagnetic actuation of superparamagnetic microbeads

    NASA Astrophysics Data System (ADS)

    Ouk, Minae; Beach, Geoffrey

    2014-03-01

    Superparamagnetic microbeads (SBs) are widely used to capture biological entities in a fluid environment. Chip-based magnetic actuation provides a means to transport SBs in lab-on-a-chip technologies. This is usually accomplished using the stray field from patterned magnetic microstructures, or domain walls in magnetic nanowires. However, lithographic patterning over a large area is costly and impractical using conventional techniques such as electron beam lithography. Here we use a simple floating-transfer technique for large-area self-assembly of polystyrene microspheres on a Si wafer to produce lithographic masks texturing a substrate. Hexagonal patterns are used as lift-off and etching masks to create magnetic dot and anti-dot arrays in CoFe thin films, with a size and spacing that can be tuned via sphere diameter and RIE etch time. Using a rotating magnetic fields, we show that these magnetically-patterned substrates can transport SBs across large distances on the wafer surface, opening the possibility to augment or replace microfluidic actuation for long distance transport. Supported by the MIT Deshpande Center.

  20. Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes

    PubMed Central

    Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

    2016-01-01

    In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication. PMID:27466010

  1. Investigation on large-area fabrication of vivid shark skin with superior surface functions

    NASA Astrophysics Data System (ADS)

    Chen, Huawei; Zhang, Xin; Ma, Lingxi; Che, Da; Zhang, Deyuan; Sudarshan, T. S.

    2014-10-01

    Shark skin has attracted worldwide attention because of its superior drag reduction, antifouling performance induced from its unique surface morphology. Although the vivid shark skin has been fabricated by a bio-replicated micro-imprinting approach in previous studies and superior drag reduction effect has been validated in water tunnel, continuous large-area fabrication is still an obstacle to wide apply. In this paper, one novel bio-replication coating technology is proposed for large-area transfer of shark skin based on rapid UV curable paint. Apart from design of coating system, bio-replication accuracy of surface morphology was validated about 97% by comparison between shark skin template and coating surface morphology. Finally, the drag reduction and anti-fouling function of coating surface were tested in water tunnel and open algae pond respectively. Drag reduction rate of coating surface was validated about 12% higher and anti-fouling was proved to about hundred times ameliorate, all of which are more excellent than simple 2D riblet surface.

  2. Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes.

    PubMed

    Xie, Xu; Jin, Sung Hun; Wahab, Muhammad A; Islam, Ahmad E; Zhang, Chenxi; Du, Frank; Seabron, Eric; Lu, Tianjian; Dunham, Simon N; Cheong, Hou In; Tu, Yen-Chu; Guo, Zhilin; Chung, Ha Uk; Li, Yuhang; Liu, Yuhao; Lee, Jong-Ho; Song, Jizhou; Huang, Yonggang; Alam, Muhammad A; Wilson, William L; Rogers, John A

    2014-11-12

    Recent progress in the field of single-walled carbon nanotubes (SWNTs) significantly enhances the potential for practical use of this remarkable class of material in advanced electronic and sensor devices. One of the most daunting challenges is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here we introduce a simple, scalable, large-area scheme that achieves this goal through microwave irradiation of aligned SWNTs grown on quartz substrates. Microstrip dipole antennas of low work-function metals concentrate the microwaves and selectively couple them into only the metallic SWNTs (m-SWNTs). The result allows for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies of the process. As one demonstration of the effectiveness, implementing this method on large arrays consisting of ~20,000 SWNTs completely removes all of the m-SWNTs (~7,000) to yield a purity of s-SWNTs that corresponds, quantitatively, to at least to 99.9925% and likely significantly higher.

  3. Further advancements for large area-detector based computed tomography system

    SciTech Connect

    Davis, A. W.; Keating, S. C.; Claytor, T. N.

    2001-01-01

    We present advancements made to a large area-detector based system for industrial x-ray computed tomography. Past performance improvements in data acquisition speeds were made by use of high-resolution large area, flat-panel amorphous-silicon (a-Si) detectors. The detectors have proven, over several years, to be a robust alternative to CCD-optics and image intensifier CT systems. These detectors also provide the advantage of area detection as compared with the single slice geometry of linear array systems. New advancements in this system include parallel processing of sinogram reconstructions, improved visualization software and migration to frame-rate a-Si detectors. Parallel processing provides significant speed improvements for data reconstruction, and is implemented for parallel-beam, fan-beam and Feldkamp cone-beam reconstruction algorithms. Reconstruction times are reduced by an order of magnitude by use of a cluster of ten or more equal-speed computers. Advancements in data visualization are made through interactive software, which allows interrogation of the full three-dimensional dataset. Inspection examples presented in this paper include an electromechanical device, a nonliving biological specimen and a press-cast plastic specimen. We also present a commonplace item for the benefit of the layperson.

  4. Confocal microscopy with strip mosaicing for rapid imaging over large areas of excised tissue

    NASA Astrophysics Data System (ADS)

    Abeytunge, Sanjee; Li, Yongbiao; Larson, Bjorg; Peterson, Gary; Seltzer, Emily; Toledo-Crow, Ricardo; Rajadhyaksha, Milind

    2013-06-01

    Confocal mosaicing microscopy is a developing technology platform for imaging tumor margins directly in freshly excised tissue, without the processing required for conventional pathology. Previously, mosaicing on 12-×-12 mm2 of excised skin tissue from Mohs surgery and detection of basal cell carcinoma margins was demonstrated in 9 min. Last year, we reported the feasibility of a faster approach called "strip mosaicing," which was demonstrated on a 10-×-10 mm2 of tissue in 3 min. Here we describe further advances in instrumentation, software, and speed. A mechanism was also developed to flatten tissue in order to enable consistent and repeatable acquisition of images over large areas. We demonstrate mosaicing on 10-×-10 mm2 of skin tissue with 1-μm lateral resolution in 90 s. A 2.5-×-3.5 cm2 piece of breast tissue was scanned with 0.8-μm lateral resolution in 13 min. Rapid mosaicing of confocal images on large areas of fresh tissue potentially offers a means to perform pathology at the bedside. Imaging of tumor margins with strip mosaicing confocal microscopy may serve as an adjunct to conventional (frozen or fixed) pathology for guiding surgery.

  5. Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes.

    PubMed

    Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

    2016-01-01

    In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication.

  6. Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes

    NASA Astrophysics Data System (ADS)

    Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

    2016-07-01

    In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication.

  7. Large area 3-D optical coherence tomography imaging of lumpectomy specimens for radiation treatment planning

    NASA Astrophysics Data System (ADS)

    Wang, Cuihuan; Kim, Leonard; Barnard, Nicola; Khan, Atif; Pierce, Mark C.

    2016-02-01

    Our long term goal is to develop a high-resolution imaging method for comprehensive assessment of tissue removed during lumpectomy procedures. By identifying regions of high-grade disease within the excised specimen, we aim to develop patient-specific post-operative radiation treatment regimens. We have assembled a benchtop spectral-domain optical coherence tomography (SD-OCT) system with 1320 nm center wavelength. Automated beam scanning enables "sub-volumes" spanning 5 mm x 5 mm x 2 mm (500 A-lines x 500 B-scans x 2 mm in depth) to be collected in under 15 seconds. A motorized sample positioning stage enables multiple sub-volumes to be acquired across an entire tissue specimen. Sub-volumes are rendered from individual B-scans in 3D Slicer software and en face (XY) images are extracted at specific depths. These images are then tiled together using MosaicJ software to produce a large area en face view (up to 40 mm x 25 mm). After OCT imaging, specimens were sectioned and stained with HE, allowing comparison between OCT image features and disease markers on histopathology. This manuscript describes the technical aspects of image acquisition and reconstruction, and reports initial qualitative comparison between large area en face OCT images and HE stained tissue sections. Future goals include developing image reconstruction algorithms for mapping an entire sample, and registering OCT image volumes with clinical CT and MRI images for post-operative treatment planning.

  8. Laser microprocessing and nanoengineering of large-area functional micro/nanostructures

    NASA Astrophysics Data System (ADS)

    Tang, M.; Xie, X. Z.; Yang, J.; Chen, Z. C.; Xu, L.; Choo, Y. S.; Hong, M. H.

    2011-12-01

    Laser microprocessing and nanoengineering are of great interest to both scientists and engineers, since the inspired properties of functional micro/nanostructures over large areas can lead to numerous unique applications. Currently laser processing systems combined with high speed automation ensure the focused laser beam to process various materials at a high throughput and a high accuracy over large working areas. UV lasers are widely used in both laser microprocessing and nanoengineering. However by improving the processing methods, green pulsed laser is capable of replacing UV lasers to make high aspect ratio micro-grooves on fragile and transparent sapphire substrates. Laser micro-texturing can also tune the wetting property of metal surfaces from hydrophilic to super-hydrophobic at a contact angle of 161° without chemical coating. Laser microlens array (MLA) can split a laser beam into multiple laser beams and reduce the laser spot size down to sub-microns. It can be applied to fabricate split ring resonator (SRR) meta-materials for THz sensing, surface plasmonic resonance (SPR) structures for NIR and molding tools for soft lithography. Furthermore, laser interference lithography combined with thermal annealing can obtain a large area of sub-50nm nano-dot clusters used for SPR applications.

  9. Conformal mechanics

    SciTech Connect

    Gonera, Joanna

    2013-08-15

    The SL(2,R) invariant Hamiltonian systems are discussed within the framework of the orbit method. It is shown that both the dynamics and the symmetry transformations are globally well-defined on phase space. The flexibility in the choice of the time variable and the Hamiltonian function described in the paper by de Alfaro et al. [Nuovo Cimento 34A (1976) 569] is related to the nontrivial global structure of 1+0-dimensional space–time. The operational definition of time is discussed.

  10. Metal-assisted exfoliation (MAE): green, roll-to-roll compatible method for transferring graphene to flexible substrates

    NASA Astrophysics Data System (ADS)

    Zaretski, Aliaksandr V.; Moetazedi, Herad; Kong, Casey; Sawyer, Eric J.; Savagatrup, Suchol; Valle, Eduardo; O'Connor, Timothy F.; Printz, Adam D.; Lipomi, Darren J.

    2015-01-01

    Graphene is expected to play a significant role in future technologies that span a range from consumer electronics, to devices for the conversion and storage of energy, to conformable biomedical devices for healthcare. To realize these applications, however, a low-cost method of synthesizing large areas of high-quality graphene is required. Currently, the only method to generate large-area single-layer graphene that is compatible with roll-to-roll manufacturing destroys approximately 300 kg of copper foil (thickness = 25 μm) for every 1 g of graphene produced. This paper describes a new environmentally benign and scalable process of transferring graphene to flexible substrates. The process is based on the preferential adhesion of certain thin metallic films to graphene; separation of the graphene from the catalytic copper foil is followed by lamination to a flexible target substrate in a process that is compatible with roll-to-roll manufacturing. The copper substrate is indefinitely reusable and the method is substantially greener than the current process that uses relatively large amounts of corrosive etchants to remove the copper. The sheet resistance of the graphene produced by this new process is unoptimized but should be comparable in principle to that produced by the standard method, given the defects observable by Raman spectroscopy and the presence of process-induced cracks. With further improvements, this green, inexpensive synthesis of single-layer graphene could enable applications in flexible, stretchable, and disposable electronics, low-profile and lightweight barrier materials, and in large-area displays and photovoltaic modules.

  11. Capturing Chromosome Conformation

    NASA Astrophysics Data System (ADS)

    Dekker, Job; Rippe, Karsten; Dekker, Martijn; Kleckner, Nancy

    2002-02-01

    We describe an approach to detect the frequency of interaction between any two genomic loci. Generation of a matrix of interaction frequencies between sites on the same or different chromosomes reveals their relative spatial disposition and provides information about the physical properties of the chromatin fiber. This methodology can be applied to the spatial organization of entire genomes in organisms from bacteria to human. Using the yeast Saccharomyces cerevisiae, we could confirm known qualitative features of chromosome organization within the nucleus and dynamic changes in that organization during meiosis. We also analyzed yeast chromosome III at the G1 stage of the cell cycle. We found that chromatin is highly flexible throughout. Furthermore, functionally distinct AT- and GC-rich domains were found to exhibit different conformations, and a population-average 3D model of chromosome III could be determined. Chromosome III emerges as a contorted ring.

  12. Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ferrara, E. C.; Harding, A. K.; McEnery, J. E.; Moiseev, A. A.; Ackemann, M.

    2012-01-01

    We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting Earth's shadow, which, is offset in opposite directions for opposite charges due to Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 and 200 Ge V. We confirm that the fraction rises with energy in the 20-100 Ge V range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.

  13. The On-Orbit Calibrations for the Fermi Large Area Telescope

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Ampe, J.; Anderson, B.; Atwood, W.B.; Axelsson, M.; Bagagli, R.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bartelt, J.; Bastieri, Denis; Baughman, B.M.; Bechtol, K.; Bederede, D.; Bellardi, F.; Bellazzini, R.; Belli, F.; Berenji, B.; Bisello, D.; /more authors..

    2011-11-17

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope began its on-orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on-orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.

  14. Development of broadband X-ray interference lithography large area exposure system

    NASA Astrophysics Data System (ADS)

    Xue, Chaofan; Wu, Yanqing; Zhu, Fangyuan; Yang, Shumin; Liu, Haigang; Zhao, Jun; Wang, Liansheng; Tai, Renzhong

    2016-04-01

    The single-exposure patterned area is about several 102 × 102 μm2 which is mainly decided by the mask area in multi-beam X-ray interference lithography (XIL). The exposure area is difficult to stitch to a larger one because the patterned area is surrounded by 0th diffraction exposure areas. To block the 0th diffraction beams precisely and effectively, a new large area exposure technology is developed in the Shanghai Synchrotron Radiation Facility by applying an order-sorting aperture with a new in situ monitoring scheme in the XIL system. The patterned area could be stitched readily up to several square centimeters and even bigger by this technology.

  15. Development of broadband X-ray interference lithography large area exposure system.

    PubMed

    Xue, Chaofan; Wu, Yanqing; Zhu, Fangyuan; Yang, Shumin; Liu, Haigang; Zhao, Jun; Wang, Liansheng; Tai, Renzhong

    2016-04-01

    The single-exposure patterned area is about several 10(2) × 10(2) μm(2) which is mainly decided by the mask area in multi-beam X-ray interference lithography (XIL). The exposure area is difficult to stitch to a larger one because the patterned area is surrounded by 0th diffraction exposure areas. To block the 0th diffraction beams precisely and effectively, a new large area exposure technology is developed in the Shanghai Synchrotron Radiation Facility by applying an order-sorting aperture with a new in situ monitoring scheme in the XIL system. The patterned area could be stitched readily up to several square centimeters and even bigger by this technology. PMID:27131667

  16. Atomic layer deposited borosilicate glass microchannel plates for large area event counting detectors

    NASA Astrophysics Data System (ADS)

    Siegmund, O. H. W.; McPhate, J. B.; Tremsin, A. S.; Jelinsky, S. R.; Hemphill, R.; Frisch, H. J.; Elam, J.; Mane, A.; Lappd Collaboration

    2012-12-01

    Borosilicate glass micro-capillary array substrates with 20 μm and 40 μm pores have been deposited with resistive, and secondary electron emissive, layers by atomic layer deposition to produce functional microchannel plates. Device formats of 32.7 mm and 20 cm square have been fabricated and tested in analog and photon counting modes. The tests show amplification, imaging, background rate, pulse shape and lifetime characteristics that are comparable to standard glass microchannel plates. Large area microchannel plates of this type facilitate the construction of 20 cm format sealed tube sensors with strip-line readouts that are being developed for Cherenkov light detection. Complementary work has resulted in Na2KSb bialkali photocathodes with peak quantum efficiency of 25% being made on borosilicate glass. Additionally GaN (Mg) opaque photocathodes have been successfully made on borosilicate microchannel plates.

  17. Analysis of volatiles present in interplanetary dust and stratospheric particles collected on large area collectors

    NASA Technical Reports Server (NTRS)

    Hartmetz, C. P.; Gibson, E. K., Jr.; Blanford, G. E.

    1991-01-01

    Results are presented from an analysis of six chondritic interplanetary dust particles (IDPs) and 22 other stratospheric particles collected on large-area collector, carried out in order to obtain information on the nature, distribution, and form of volatiles in IDPs. A laser microprobe/mass spectrometer (LMMS) was used to extract volatile elements and molecules from particles larger than 10 microns, and an improved hexane rinsing technique was developed for the removal of contaminants. Results show that, because of contamination from silicone oil, freon, and hexane, most of the LMMS signal from IDPs can be interpreted as arising from contamination. Therefore, a species was not considered indigenous unless the signal was an order of magnitude greater in abundance than that released from a pure contaminant coated on gold.

  18. Chemical characterization of seven Large Area Collector particles by SXRF. [cosmic dust composition

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Sutton, S. R.

    1991-01-01

    Optical microscopy and synchrotron X-ray fluorescence (SXRF) are used to analyze the chemical composition of seven dark-appearing cosmic-dust particles obtained in the stratosphere during NASA Johnson Large Area Collector flights. The experimental setup and procedures are outlined, and the results are presented in extensive tables. Three of the particles had abundances similar to those of chondrites (except for low Ca values in one particle); two had a metallic appearance and spectra dominated by Fe and Zn; one contained Cu and Cr plus small amounts of Fe and Zn; and one had igneous-type abundances of minor and trace elements while containing all of the elements seen in chondritic particles, suggesting it may be of extraterrestrial origin.

  19. Large area CMOS bio-pixel array for compact high sensitive multiplex biosensing.

    PubMed

    Sandeau, Laure; Vuillaume, Cassandre; Contié, Sylvain; Grinenval, Eva; Belloni, Federico; Rigneault, Hervé; Owens, Roisin M; Fournet, Margaret Brennan

    2015-02-01

    A novel CMOS bio-pixel array which integrates assay substrate and assay readout is demonstrated for multiplex and multireplicate detection of a triplicate of cytokines with single digit pg ml(-1) sensitivities. Uniquely designed large area bio-pixels enable individual assays to be dedicated to and addressed by single pixels. A capability to simultaneously measure a large number of targets is provided by the 128 available pixels. Chemiluminescent assays are carried out directly on the pixel surface which also detects the emitted chemiluminescent photons, facilitating a highly compact sensor and reader format. The high sensitivity of the bio-pixel array is enabled by the high refractive index of silicon based pixels. This in turn generates a strong supercritical angle luminescence response significantly increasing the efficiency of the photon collection over conventional farfield modalities. PMID:25490928

  20. Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

    DOEpatents

    Leung, Ka-Ngo; Gordon, K.C.; Kippenhan, D.O.; Purgalis, P.; Moussa, D.; Williams, M.D.; Wilde, S.B.; West, M.W.

    1987-10-16

    A large area directly heated lanthanum hexaboride (LaB/sub 6/) cathode system is disclosed. The system comprises a LaB/sub 6/ cathode element generally circular in shape about a central axis. The cathode element has a head with an upper substantially planar emission surface, and a lower downwardly and an intermediate body portion which diminishes in cross-section from the head towards the base of the cathode element. A central rod is connected to the base of the cathode element and extends along the central axis. Plural upstanding spring fingers are urged against an outer peripheral contact surface of the head end to provide a mechanical and electrical connection to the cathode element. 7 figs