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Sample records for engineering structures iii

  1. Molecular beam epitaxy engineered III-V semiconductor structures for low-power optically addressed spatial light modulators

    NASA Technical Reports Server (NTRS)

    Larsson, Anders G.; Maserjian, Joseph

    1992-01-01

    Device approaches are investigated for optically addressed SLMs based on molecular-beam epitaxy (MBE) engineered III-V materials and structures. Strong photooptic effects can be achieved in periodically delta-doped multiple-quantum-well structures, but are still insufficient for high-contrast modulation with only single- or double-pass absorption through active layers of practical thickness. The asymmetric Fabry-Perot cavity approach is employed to permit extinction of light due to interference of light reflected from the front and back surfaces of the cavity. This approach is realized with an all-MBE-grown structure consisting of GaAs/AlAs quarter-wave stack reflector grown over the GaAs substrate as the high reflectance mirror and the GaAs surface as the low reflectance mirror. High-contrast modulation is achieved using a low-power InGaAs/GaAs quantum well laser for the control signal.

  2. NIF Title III engineering plan

    SciTech Connect

    Deis, G

    1998-06-01

    The purpose of this document is to define the work that must be accomplished by the NIF Project during Title III Engineering. This definition is intended to be sufficiently detailed to provide a framework for yearly planning, to clearly identify the specific deliverables so that the Project teams can focus on them, and to provide a common set of objectives and processes across the Project. This plan has been preceded by similar documents for Title I and Title II design and complements the Site Management Plan, the Project Control Manual, the Quality Assurance Program Plan, the RM Parsons NIF Title III Configuration Control Plan, the Integrated Project Schedule, the Preliminary Safety Analysis Report, the Configuration Management Plan, and the Transition Plan.

  3. LM1500 Engine Marinization Contract. Phase III. Materials and Processes Development for Phase III Engine Components.

    DTIC Science & Technology

    The purpose of this report is to briefly document the principal difficulties encountered and the solutions which were effected in the course of manufacturing the modified Phase III test engine hardware. (Author)

  4. Structural Engineering: Overview

    NASA Technical Reports Server (NTRS)

    Castro, Edgar

    2011-01-01

    This slide presentation presents the work of the Structural Engineering Division of the Engineering Directorate. The work includes: providing technical expertise and leadership for the development, evaluation, and operation of structural, mechanical, and thermal spaceflight systems.

  5. ARIES-III divertor engineering design

    SciTech Connect

    Wong, C.P.C.; Schultz, K.R.; Cheng, E.T.; Grotz, S.; Hasan, M.A.; Najmabadi, F.; Sharafat, S.; Brooks, J.N.; Ehst, D.A.; Sze, D.K.; Herring, J.S.; Valenti, M.; Steiner, D.

    1992-01-01

    This paper reports the engineering design of the ARIES-III double- null divertor. The divertor coolant tubes are made from W-3Re alloy and cooled by subcooled flow boiling of organic coolant. A coating of 4 mm thick tungsten is plasma sprayed onto the divertor surface. This W layer can withstand the thermal deposition of a few disruptions. At a maximum surface heat flux of 5.4 MW/m{sup 2}, a conventional divertor design can be used. The divertor surface is contoured to have a constant heat flux of 5.4 MW/m{sup 2}. The net erosion of the W-surface was found to be negligible at about 0.1 mm/year. After 3 years of operation, the W-3Re alloy ARIES-III divertor can be disposed of as Class A waste. In order to control the prompt dose release at site boundary to less than 200 Rem, isotopic tailoring of the W-alloy will be needed.

  6. VIPR III VADR SPIDER Structural Design and Analysis

    NASA Technical Reports Server (NTRS)

    Li, Wesley; Chen, Tony

    2016-01-01

    In support of the National Aeronautics and Space Administration (NASA) Vehicle Integrated Propulsion Research (VIPR) Phase III team to evaluate the volcanic ash environment effects on the Pratt & Whitney F117-PW-100 turbofan engine, NASA Armstrong Flight Research Center has successfully performed structural design and analysis on the Volcanic Ash Distribution Rig (VADR) and the Structural Particulate Integration Device for Engine Research (SPIDER) for the ash ingestion test. Static and dynamic load analyses were performed to ensure no structural failure would occur during the test. Modal analysis was conducted, and the results were used to develop engine power setting avoidance zones. These engine power setting avoidance zones were defined to minimize the dwell time when the natural frequencies of the VADR/SPIDER system coincided with the excitation frequencies of the engine which was operating at various revolutions per minute. Vortex-induced vibration due to engine suction air flow during the ingestion test was also evaluated, but was not a concern.

  7. Computer Education for Engineers, Part III.

    ERIC Educational Resources Information Center

    McCullough, Earl S.; Lofy, Frank J.

    1989-01-01

    Reports the results of the third survey of computer use in engineering education conducted in the fall of 1987 in comparing with 1981 and 1984 results. Summarizes survey data on computer course credits, languages, equipment use, CAD/CAM instruction, faculty access, and computer graphics. (YP)

  8. Structural characterization of Spinacia oleracea trypsin inhibitor III (SOTI-III).

    PubMed

    Glotzbach, Bernhard; Schmelz, Stefan; Reinwarth, Michael; Christmann, Andreas; Heinz, Dirk W; Kolmar, Harald

    2013-01-01

    In recent decades, several canonical serine protease inhibitor families have been classified and characterized. In contrast to most trypsin inhibitors, those from garden four o'clock (Mirabilis jalapa) and spinach (Spinacia oleracea) do not share sequence similarity and have been proposed to form the new Mirabilis serine protease inhibitor family. These 30-40-amino-acid inhibitors possess a defined disulfide-bridge topology and belong to the cystine-knot miniproteins (knottins). To date, no atomic structure of this inhibitor family has been solved. Here, the first structure of S. oleracea trypsin inhibitor III (SOTI-III), in complex with bovine pancreatic trypsin, is reported. The inhibitor was synthesized by solid-phase peptide synthesis on a multi-milligram scale and was assayed to test its inhibitory activity and binding properties. The structure confirmed the proposed cystine-bridge topology. The structural features of SOTI-III suggest that it belongs to a new canonical serine protease inhibitor family with promising properties for use in protein-engineering and medical applications.

  9. Composite mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1989-01-01

    Recent research activities and accomplishments at Lewis Research Center on composite mechanics for engine structures are summarized. The activities focused mainly on developing procedures for the computational simulation of composite intrinsic and structural behavior. The computational simulation encompasses all aspects of composite mechanics, advanced three-dimensional finite-element methods, damage tolerance, composite structural and dynamic response, and structural tailoring and optimization.

  10. Composite mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1987-01-01

    Recent research activities and accomplishments at Lewis Research Center on composite mechanics for engine structures are summarized. The activities focused mainly on developing procedures for the computational simulation of composite intrinsic and structural behavior. The computational simulation encompasses all aspects of composite mechanics, advanced three-dimensional finite-element methods, damage tolerance, composite structural and dynamic response, and structural tailoring and optimization.

  11. Structural characterization of dimeric murine aminoacylase III.

    PubMed

    Ryazantsev, Sergey; Abuladze, Natalia; Newman, Debra; Bondar, Galyna; Kurtz, Ira; Pushkin, Alexander

    2007-05-01

    Aminoacylase III (AAIII) plays an important role in deacetylation of acetylated amino acids and N-acetylated S-cysteine conjugates of halogenated alkenes and alkanes. AAIII, recently cloned from mouse kidney and partially characterized, is a mixture of tetramers and dimers. In the present work, AAIII dimers were purified and shown to be enzymatically active. Limited trypsinolysis showed two domains of approximately 9 and 25 kDa. The three-dimensional structure of the dimer was studied by electron microscopy of negative stained samples and by single-particle reconstruction. A 16A resolution model of the AAIII dimer was created. It has an unusual, cage-like, structure. A realistic AAIII tetramer model was built from two dimers.

  12. Engine Structural Analysis Software

    NASA Technical Reports Server (NTRS)

    McKnight, R. L.; Maffeo, R. J.; Schrantz, S.; Hartle, M. S.; Bechtel, G. S.; Lewis, K.; Ridgway, M.; Chamis, Christos C. (Technical Monitor)

    2001-01-01

    The report describes the technical effort to develop: (1) geometry recipes for nozzles, inlets, disks, frames, shafts, and ducts in finite element form, (2) component design tools for nozzles, inlets, disks, frames, shafts, and ducts which utilize the recipes and (3) an integrated design tool which combines the simulations of the nozzles, inlets, disks, frames, shafts, and ducts with the previously developed combustor, turbine blade, and turbine vane models for a total engine representation. These developments will be accomplished in cooperation and in conjunction with comparable efforts of NASA Glenn Research Center.

  13. The Structure of Bis(phthalocyaninato)neodymium(III).

    DTIC Science & Technology

    1980-06-01

    synthesis of lanthanide (III) phthalocyanine complexes 1 was established by Kirin and Moskalev, many studies on their composi- 2 tions and properties have...been reported. For instance, intense attention has been directed toward electrochromism of bis(phthalocyaninato) lanthanide (III) complexes , Pc2Ln(III)H...The structural analysis of bis(phthalocyaninato) lanthanide (III) complexes would provide useful information to investigate their electo- chromuism, and

  14. Military engine computational structures technology

    NASA Technical Reports Server (NTRS)

    Thomson, Daniel E.

    1992-01-01

    Integrated High Performance Turbine Engine Technology Initiative (IHPTET) goals require a strong analytical base. Effective analysis of composite materials is critical to life analysis and structural optimization. Accurate life prediction for all material systems is critical. User friendly systems are also desirable. Post processing of results is very important. The IHPTET goal is to double turbine engine propulsion capability by the year 2003. Fifty percent of the goal will come from advanced materials and structures, the other 50 percent will come from increasing performance. Computer programs are listed.

  15. High temperature turbine engine structure

    DOEpatents

    Boyd, Gary L.

    1991-01-01

    A high temperature turbine engine includes a rotor portion having axially stacked adjacent ceramic rotor parts. A ceramic/ceramic joint structure transmits torque between the rotor parts while maintaining coaxial alignment and axially spaced mutually parallel relation thereof despite thermal and centrifugal cycling.

  16. High temperature turbine engine structure

    DOEpatents

    Boyd, Gary L.

    1990-01-01

    A high temperature turbine engine includes a hybrid ceramic/metallic rotor member having ceramic/metal joint structure. The disclosed joint is able to endure higher temperatures than previously possible, and aids in controlling heat transfer in the rotor member.

  17. Evolution of corundum-structured III-oxide semiconductors: Growth, properties, and devices

    NASA Astrophysics Data System (ADS)

    Fujita, Shizuo; Oda, Masaya; Kaneko, Kentaro; Hitora, Toshimi

    2016-12-01

    The recent progress and development of corundum-structured III-oxide semiconductors are reviewed. They allow bandgap engineering from 3.7 to ∼9 eV and function engineering, leading to highly durable electronic devices and deep ultraviolet optical devices as well as multifunctional devices. Mist chemical vapor deposition can be a simple and safe growth technology and is advantageous for reducing energy and cost for the growth. This is favorable for the wide commercial use of devices at low cost. The III-oxide semiconductors are promising candidates for new devices contributing to sustainable social, economic, and technological development for the future.

  18. Ribonuclease revisited: structural insights into ribonuclease III family enzymes.

    PubMed

    MacRae, Ian J; Doudna, Jennifer A

    2007-02-01

    Ribonuclease III (RNase III) enzymes occur ubiquitously in biology and are responsible for processing RNA precursors into functional RNAs that participate in protein synthesis, RNA interference and a range of other cellular activities. Members of the RNase III enzyme family, including Escherichia coli RNase III, Rnt1, Dicer and Drosha, share the ability to recognize and cleave double-stranded RNA (dsRNA), typically at specific positions or sequences. Recent biochemical and structural data have shed new light on how RNase III enzymes catalyze dsRNA hydrolysis and how substrate specificity is achieved. A major theme emerging from these studies is that accessory domains present in different RNase III enzymes are the key determinants of substrate selectivity, which in turn dictates the specialized biological function of each type of RNase III protein.

  19. Biochemical and Structural Properties of Mouse Kynurenine Aminotransferase III

    SciTech Connect

    Han, Q.; Robinson, H; Cai, T; Tagle, D; Li, J

    2009-01-01

    Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.

  20. Biochemical and structural properties of mouse kynurenine aminotransferase III.

    PubMed

    Han, Qian; Robinson, Howard; Cai, Tao; Tagle, Danilo A; Li, Jianyong

    2009-02-01

    Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60 degrees C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.

  1. Synthesis, crystal structure and magnetism of iron(III) and manganese(III) dipicolinates with pyridinemethanols

    NASA Astrophysics Data System (ADS)

    Uhrecký, Róbert; Pavlik, Ján; Růžičková, Zdeňka; Dlháň, Ľubor; Koman, Marian; Boča, Roman; Moncoľ, Ján

    2014-11-01

    Four ionic iron(III) and manganese(III) dipicolinato complexes of the formula (2-pymeH) [FeIII(dipic)2]ṡ[FeIII(H2O)2Cl(dipic)]ṡ2H2O, (3-pymeH)[MnIII(dipic)2]ṡ1.5H2O, (4-pymeH)[FeIII(dipic)2]ṡ2H2O and (4-pymeH)[MnIII(dipic)2]ṡ2H2O, where H2dipic = pyridine-2,6-dicarboxylic acid, 2-pyme = 2-pyridinemethanol, 3-pyme = 3-pyridinemethanol, 4-pyme = 4-pyridinemethanol, have been prepared and characterized by the single-crystal X-ray structure analysis, infrared spectroscopy and magnetic measurements. The magnetic data were fitted to a zero-field splitting model revealing a slight magnetic anisotropy for Mn(III) systems. The molecular field correction was consistently formulated and included in the analysis for both, magnetic susceptibility and magnetization data.

  2. The Mathematical Disposition of Structural Engineers

    ERIC Educational Resources Information Center

    Gainsburg, Julie

    2007-01-01

    This ethnographic study investigated the mathematical disposition of engineers. Structural engineers in two firms were observed in everyday practice. Observation and interview data were analyzed to elucidate the role of mathematics in solving engineering problems and the engineers' perceptions of the status of mathematics relative to other…

  3. Nucleosome Positioning and NDR Structure at RNA Polymerase III Promoters

    PubMed Central

    Helbo, Alexandra Søgaard; Lay, Fides D.; Jones, Peter A.; Liang, Gangning; Grønbæk, Kirsten

    2017-01-01

    Chromatin is structurally involved in the transcriptional regulation of all genes. While the nucleosome positioning at RNA polymerase II (pol II) promoters has been extensively studied, less is known about the chromatin structure at pol III promoters in human cells. We use a high-resolution analysis to show substantial differences in chromatin structure of pol II and pol III promoters, and between subtypes of pol III genes. Notably, the nucleosome depleted region at the transcription start site of pol III genes extends past the termination sequences, resulting in nucleosome free gene bodies. The +1 nucleosome is located further downstream than at pol II genes and furthermore displays weak positioning. The variable position of the +1 location is seen not only within individual cell populations and between cell types, but also between different pol III promoter subtypes, suggesting that the +1 nucleosome may be involved in the transcriptional regulation of pol III genes. We find that expression and DNA methylation patterns correlate with distinct accessibility patterns, where DNA methylation associates with the silencing and inaccessibility at promoters. Taken together, this study provides the first high-resolution map of nucleosome positioning and occupancy at human pol III promoters at specific loci and genome wide. PMID:28176797

  4. Nucleosome Positioning and NDR Structure at RNA Polymerase III Promoters

    NASA Astrophysics Data System (ADS)

    Helbo, Alexandra Søgaard; Lay, Fides D.; Jones, Peter A.; Liang, Gangning; Grønbæk, Kirsten

    2017-02-01

    Chromatin is structurally involved in the transcriptional regulation of all genes. While the nucleosome positioning at RNA polymerase II (pol II) promoters has been extensively studied, less is known about the chromatin structure at pol III promoters in human cells. We use a high-resolution analysis to show substantial differences in chromatin structure of pol II and pol III promoters, and between subtypes of pol III genes. Notably, the nucleosome depleted region at the transcription start site of pol III genes extends past the termination sequences, resulting in nucleosome free gene bodies. The +1 nucleosome is located further downstream than at pol II genes and furthermore displays weak positioning. The variable position of the +1 location is seen not only within individual cell populations and between cell types, but also between different pol III promoter subtypes, suggesting that the +1 nucleosome may be involved in the transcriptional regulation of pol III genes. We find that expression and DNA methylation patterns correlate with distinct accessibility patterns, where DNA methylation associates with the silencing and inaccessibility at promoters. Taken together, this study provides the first high-resolution map of nucleosome positioning and occupancy at human pol III promoters at specific loci and genome wide.

  5. America's Century III--The Engineer's Opportunity and Responsibility

    ERIC Educational Resources Information Center

    Miller, Cheryl

    1976-01-01

    Presents highlights of the addresses of Arthur G. Hansen, Robert C. Seamans, Jr., and Edward R. Kane to the plenary session of the annual conference of the American Society for Engineering Education. Topics include energy, economics, governmental regulation, and the role of minorities and women in engineering in the coming century. (SL)

  6. Engineering Modeling Study. Volume III. CORDIVEM/Engineer Module Interface Manual.

    DTIC Science & Technology

    1982-09-01

    will tend to avoid open areas and re- quest bridges in areas with good cover. The algorithm for scoring defensibility: 1 Mobility Operations I. Scores...path. the clearing of specific obstacles. The algorithm selects locations where roads cross areas For the first version of CORDIVEM (CORDIVEM that have...mechanism to create engineer work package- 9 .~~~~ -- - - - - ---- . - -~- 3 PROGRAM STRUCTURE wide swath between the two and a link table connect

  7. Structure-function analyses of plant type III polyketide synthases.

    PubMed

    Weng, Jing-Ke; Noel, Joseph P

    2012-01-01

    Plant type III polyketide synthases (PKSs) form a superfamily of biosynthetic enzymes involved in the production of a plethora of polyketide-derived natural products important for ecological adaptations and the fitness of land plants. Moreover, tremendous interest in bioengineering of type III PKSs to produce high-value compounds is increasing. Compared to type I and type II PKSs, which form either large modular protein complexes or dissociable molecular assemblies, type III PKSs exist as smaller homodimeric proteins, technically more amenable for detailed quantitative biochemical and phylogenetic analyses. In this chapter, we summarize a collection of approaches, including bioinformatics, genetics, protein crystallography, in vitro biochemistry, and mutagenesis, together affording a comprehensive interrogation of the structure-function-evolutionary relationships in the plant type III PKS family.

  8. Results of Component and Engineering Unit Tests of the ACRIM III Radiometer (Invited)

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; Socker, D. G.; Thernisien, A. F.; McMullin, D. R.; Shirley, E. L.; Hanssen, L. M.; Zeng, J.; Lorentz, S. R.

    2013-12-01

    As part of a NASA-Sponsored program to understand the differences in Total Solar Irradiance (TSI) results reported by ACRIM III on ACRIMSAT and TIM on SORCE, a series of tests and modeling studies of ACRIM III instrument component as well as tests of the ACRIM III engineering unit have been conducted. The modeling effort involves estimating the contribution of diffraction on the TSI results and the measurements involve the determination of this diffraction contribution as well as contributions due to scattered light and the cavity reflectance. The tests of the engineering unit were performed at the TRF (TSI Radiometer Facility) at LASP/Univ. of Colorado and were conducted in both power and irradiance mode. In this presentation we will describe the results of these studies and how these results compare with the recent tests of ACRIM III sensors at the LASP / TRF facility. This work is sponsored by NASA Earth Science Division.

  9. Extreme Band Engineering of III-Nitride Nanowire Heterostructures for Electronic and Photonic Application

    NASA Astrophysics Data System (ADS)

    Sarwar, ATM Golam

    Bottom-up nanowires are attractive for realizing semiconductor devices with extreme heterostructures because strain relaxation through the nanowire sidewalls allows the combination of highly lattice mismatched materials without creating dislocations. The resulting nanowires are used to fabricate light-emitting diodes (LEDs), lasers, solar cells, and sensors. The aim of this work is to investigate extreme heterostructures, which are impossible or very hard to realize in conventional planar films, exploiting the strain accommodation property of nanowires and engineer their band structure for novel electronic and photonic applications. To this end, in this thesis, III-Nitride semiconductor nanowires are investigated. In the first part of this work, a complete growth phase diagram of InN nanowires on silicon using plasma assisted molecular beam epitaxy is developed, and structural and optical characteristics are mapped as a function of growth parameters. Next, a novel up-side down pendeoepitaxial growth of InN forming mushroom-like microstructures is demonstrated and detail structural and optical characterizations are performed. Based on this, a method to grow strain-free large area single crystalline InN or thin film is proposed and the growth of InN on patterned GaN is investigated. The optimized growth conditions developed for InN are further used to grow InGaN nanowires graded over the whole composition range. Numerical energy band simulation is performed to better understand the effect of polarization charge on photo-carrier transport in these extremely graded nanowires. A novel photodetector device with negative differential photocurrent is demonstrated using the graded InGaN nanowires. In the second part of this thesis, polarization-induced nanowire light emitting diodes (PINLEDs) are investigated. The electrical and optical properties of the nanowire heterostructure are engineered and optimized for ultraviolet and deep ultraviolet applications. The electrical

  10. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1992-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  11. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1994-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  12. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1993-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  13. Outer planet probe engineering model structural tests

    NASA Technical Reports Server (NTRS)

    Smittkamp, J. A.; Gustin, W. H.; Griffin, M. W.

    1977-01-01

    A series of proof of concept structural tests was performed on an engineering model of the Outer Planets Atmospheric Entry Probe. The tests consisted of pyrotechnic shock, dynamic and static loadings. The tests partially verified the structural concept.

  14. Low dimensional III-V compound semiconductor structures

    NASA Astrophysics Data System (ADS)

    Kobayashi, Nobuhiko P.

    2009-08-01

    Material incompatibilities among dissimilar group III-V compound semiconductors (III-V CSs) often place limits on combining epitaxial thin films, however low-dimensional epitaxial structures (e.g., quantum dots and nanowires) demonstrate coherent growth even on incompatible surfaces. First, InAs QDs grown by molecular beam epitaxy on GaAs are described. Two-dimensional to three-dimensional morphological transition, lateral size evolution and vertical alignment of InAs QDs in a single and multiple stacks will be illustrated. Second, InP nanowires grown on non-single crystalline surfaces by metal organic chemical vapor deposition are described with the view toward applications where III-V CSs are functionally integrated onto various material platforms.

  15. Engineered Magnetic Core-Shell Structures.

    PubMed

    Alavi Nikje, Mir Mohammad; Vakili, Maryam

    2015-01-01

    In recent years, engineered magnetic core-shell structures are playing an important role in the wide range of various applications. These magnetic core-shell structures have attracted considerable attention because of their unique properties and various applications. Also, the synthesis of engineered magnetic core-shell structures has attracted practical interest because of potential applications in areas such as ferrofluids, medical imaging, drug targeting and delivery, cancer therapy, separations, and catalysis. So far a large number of engineered magnetic core-shell structures have been successfully synthesized. This review article focuses on the recent progress in synthesis and characterization of engineered magnetic core-shell structures. Also, this review gives a brief description of the various application of these structures. It is hoped that this review will play some small part in helping future developments in important field.

  16. Double Sided Si(Ge)/Sapphire/III-Nitride Hybrid Structure

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor)

    2016-01-01

    One aspect of the present invention is a double sided hybrid crystal structure including a trigonal Sapphire wafer containing a (0001) C-plane and having front and rear sides. The Sapphire wafer is substantially transparent to light in the visible and infrared spectra, and also provides insulation with respect to electromagnetic radio frequency noise. A layer of crystalline Si material having a cubic diamond structure aligned with the cubic <111> direction on the (0001) C-plane and strained as rhombohedron to thereby enable continuous integration of a selected (SiGe) device onto the rear side of the Sapphire wafer. The double sided hybrid crystal structure further includes an integrated III-Nitride crystalline layer on the front side of the Sapphire wafer that enables continuous integration of a selected III-Nitride device on the front side of the Sapphire wafer.

  17. Structural Insights into Fibronectin Type III Domain Mediated Signaling

    PubMed Central

    Bencharit, Sompop; Cui, Cai Bin; Siddiqui, Adnan; Howard-Williams, Escher L.; Sondek, John; Zuobi-Hasona, Kheir; Aukhil, Ikramuddin

    2007-01-01

    The alternatively spliced type-III extradomain B (EIIIB) of Fibronectin (FN) is only expressed during embryogenesis, wound healing and tumorigenesis. The biological function of this domain remains unclear. We describe here the first crystal structure of the interface between alternatively-spliced domain EIIIB and its adjacent FN type-III domain 8 (FN B-8). The opened CC′ loop of EIIIB and the rotation and tilt of EIIIB domain allows good access to the FG loop of FN-8 which is normally hindered by the CC′ loop of FN-7. In addition, the AGEGIP sequence of the CC′ loop of EIIIB replaces the NGQQGN sequence of the CC′ loop of FN-7. Finally, the CC” loop of EIIIB forms an acidic groove with FN-8. These structural findings warrant future studies directed at identifying potential binding partners for FN B-8 interface, linking EIIIB to skeletal and cartilagenous development, wound healing, and tumorigenesis, respectively. PMID:17261313

  18. Synthesis and structural characterization of new dithiocarbamate complexes from Sb(III) and Bi(III)

    SciTech Connect

    Jamaluddin, Nur Amirah; Baba, Ibrahim

    2013-11-27

    Twenty new antimony and bismuth dithiocarbamate complexes which employed ten different type of amines have been successfully synthesized. The synthesized complexes with metal to dithiocarbamate ratio at 1:3. Elemental analysis of the complexes gave the general formula of MCl[S{sub 2}CNR’R”]{sub 2} where M = Sb(III), Bi(III); R’ = methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, benzyl; R” = ethanol, methyl, ethyl, propyl, isopropyl, cyclohexyl, benzyl. The complexes were analysed by IR and NMR spectroscopy. The crystal structure of five-coordinated antimony (III) complex have been determined by X-ray single crystal diffraction. Single crystal X-ray diffraction studies on SbCl[S{sub 2}CN(C{sub 4}H{sub 9})(C{sub 2}H{sub 5})]{sub 2} adopted a triclinic system with a space group P1 with a = 10.0141(8) Å, b = 10.1394(7) Å, c = 11.8665(9) Å, α = 67.960°, β =87.616°, γ = 80.172°.

  19. Structural tailoring of engine blades (STAEBL)

    NASA Technical Reports Server (NTRS)

    Platt, C. E.; Pratt, T. K.; Brown, K. W.

    1982-01-01

    A mathematical optimization procedure was developed for the structural tailoring of engine blades and was used to structurally tailor two engine fan blades constructed of composite materials without midspan shrouds. The first was a solid blade made from superhybrid composites, and the second was a hollow blade with metal matrix composite inlays. Three major computerized functions were needed to complete the procedure: approximate analysis with the established input variables, optimization of an objective function, and refined analysis for design verification.

  20. Strain Engineering of Epitaxially Transferred, Ultrathin Layers of III-V Semiconductor on Insulator

    DTIC Science & Technology

    2011-01-01

    patterned width of 350 nm–5 m and wet etched using a mixture of citric acid 1 g/ml in de-ionized DI H2O and hydrogen peroxide 30% at 1:20 volume...Strain engineering of epitaxially transferred, ultrathin layers of III-V semiconductor on insulator Hui Fang,1,2,3 Morten Madsen,1,2,3 Carlo Carraro...10.1063/1.3537963 III-V compound semiconductors have been extensively explored in the recent years for energy-efficient and high- speed electronics due

  1. Design and Development of Stress Engineering Techniques for III-Nitride Epitaxy on Si

    NASA Astrophysics Data System (ADS)

    Leathersich, Jeff

    III-Nitrides have been a heavily researched material system for decades. Their material properties are favorable for a number of applications, most commonly in the optoelectronic and power device industry. Currently a majority of commercialized devices are fabricated on sapphire and SiC substrates but these are expensive and limit the widespread commercialization of the technology. There is substantial ongoing research geared toward the development of GaN on Si substrates because of the significant cost saving that would be realized through the inexpensive, large wafer and maturity of Si fabrication. Significant challenges with the deposition of GaN on Si have, thus far, prevented its wide-spread commercialization specifically the large lattice mismatch and thermal expansion coefficient mismatch. Both of these issues can be overcome by engineering the stress levels in the films. In this thesis work close examination and exploration of the stress formation and evolution in GaN-on-Si is performed. Methods of improving stress levels are developed in addition to providing a deeper understanding of the stress evolution process. A commonly used methodology of engineering stress levels is to use an AlGaN multi-layer stack. The first layer in the stack is an AlN buffer layer. Typical deposition methods for AlN leaves the surface rough and not ideal for subsequent epitaxy. Here, two specific modifications to the conventional deposition process are made which yield dramatic improvement in material quality and stress levels of an overgrown GaN layer. Full width at half maximum measurements from HRXRD rocking curve of GaN grown on the modified buffers show a 2x reduction and ~0.45 GPa greater built-in compressive stress in the films. A semi-empirical model to predict stress evolution in III-Nitrides is established using both fundamentals and experimental data. The model will allow researchers determine the desired stress levels in the films in advance of Epitaxy. This will

  2. Structural and electronic properties of monolayer group III monochalcogenides

    NASA Astrophysics Data System (ADS)

    Demirci, S.; Avazlı, N.; Durgun, E.; Cahangirov, S.

    2017-03-01

    We investigate the structural, mechanical, and electronic properties of the two-dimensional hexagonal structure of group III-VI binary monolayers, M X (M =B , Al, Ga, In and X =O , S, Se, Te) using first-principles calculations based on the density functional theory. The structural optimization calculations and phonon spectrum analysis indicate that all of the 16 possible binary compounds are thermally stable. In-plane stiffness values cover a range depending on the element types and can be as high as that of graphene, while the calculated bending rigidity is found to be an order of magnitude higher than that of graphene. The obtained electronic band structures show that M X monolayers are indirect band-gap semiconductors. The calculated band gaps span a wide optical spectrum from deep ultraviolet to near infrared. The electronic structure of oxides (M O ) is different from the rest because of the high electronegativity of oxygen atoms. The dispersions of the electronic band edges and the nature of bonding between atoms can also be correlated with electronegativities of constituent elements. The unique characteristics of group III-VI binary monolayers can be suitable for high-performance device applications in nanoelectronics and optics.

  3. Crystal Engineering: from Structure to Function

    NASA Astrophysics Data System (ADS)

    Hollingsworth, Mark D.

    2002-03-01

    Modern crystal engineering has emerged as a rich discipline whose success requires an iterative process of synthesis, crystallography, crystal structure analysis, and computational methods. By focusing on the molecular recognition events during nucleation and growth, chemists have uncovered new ways of controlling the internal structure and symmetry of crystals and of producing materials with useful chemical and physical properties.

  4. Biodegradable polymeric fiber structures in tissue engineering.

    PubMed

    Tuzlakoglu, Kadriye; Reis, Rui L

    2009-03-01

    Tissue engineering offers a promising new approach to create biological alternatives to repair or restore function of damaged or diseased tissues. To obtain three-dimensional tissue constructs, stem or progenitor cells must be combined with a highly porous three-dimensional scaffold, but many of the structures purposed for tissue engineering cannot meet all the criteria required by an adequate scaffold because of lack of mechanical strength and interconnectivity, as well as poor surface characteristics. Fiber-based structures represent a wide range of morphological and geometric possibilities that can be tailored for each specific tissue-engineering application. The present article overviews the research data on tissue-engineering therapies based on the use of biodegradable fiber architectures as a scaffold.

  5. Development of Cryogenic Engine for GSLV MkIII: Technological Challenges

    NASA Astrophysics Data System (ADS)

    Praveen, RS; Jayan, N.; Bijukumar, KS; Jayaprakash, J.; Narayanan, V.; Ayyappan, G.

    2017-02-01

    Cryogenic engine capable of delivering 200 kN thrust is being developed for the first time in the country by ISRO for powering the upper stage of GSLV Mk-III, the next generation launch vehicle of ISRO capable of launching four tonne class satellites to Geo-synchronous Transfer Orbit(GTO). Development of this engine started a decade ago when various sub-systems development and testing were taken up. Starting with injector element development, the design, realization and testing of the major sub-systems viz the gas generator, turbopumps, start-up system and thrust chamber have been successfully done in a phased manner before conducting a series of developmental tests in the integrated engine mode. Apart from the major sub-systems, many critical components like the igniter, control components etc were independently developed and qualified. During the development program many challenges were faced in almost all areas of propulsion engineering. Systems engineering of the engine was another key challenge in the realization. This paper gives an outlook on various technological challenges faced in the key areas related to the engine development, insight to the solutions and measures taken to overcome the challenges.

  6. Group III-nitride based hetero and quantum structures

    NASA Astrophysics Data System (ADS)

    Monemar, B.; Pozina, G.

    2000-11-01

    The present paper attempts an overview of a presently very active research field: the III-nitrides and their interesting possibilities for a range of device applications employing heterostructures and low-dimensional quantum structures. The family of materials containing AlN, GaN, InN and the alloys between them span a range of direct bandgaps between 6.2 and 1.9 eV, with very large band offsets in type I heterojunctions, which is very favourable for a number of interesting device concepts. A very important feature of these materials is the dominant influence of strong polarisation fields (spontaneous as well as piezo-electric) on the physical properties of multilayer structures, as well as on devices. Exciton binding energies are large, and excitonic effects are therefore important at room temperature. Many alloy systems, in particular InGaN, have a high miscibility gap, leading to a strong tendency for phase separation and consequently to many novel physical properties which yet have to be explored in detail. Localization effects for carriers and excitons are very important in quantum structures based on these alloys. Devices based on III-N heterostructures cover a wide range, from optical devices (violet lasers, LEDs covering a range from UV to red, white LEDs, photodetectors, UV cameras) to high-frequency power devices, both unipolar transistors (AlGaN/GaN HEMTs) and bipolar HBTs.

  7. Magneto-Structural Analysis of Iron(III) Keggin Polyoxometalates.

    PubMed

    Bandeira, Nuno A G; Sadeghi, Omid; Woods, Toby J; Zhang, Yuan-Zhu; Schnack, Jürgen; Dunbar, Kim; Nyman, May; Bo, Carles

    2017-02-16

    A computational study and magnetic susceptibility measurements of three homonuclear Fe(III) Keggin structures are herein presented: the [FeO4@Fe12F24(μ-OCH3)12](5-) anion (1), the [Bi6{FeO4@Fe12O12(OH)12}(μ-O2CCCl3)12](+) cation (2) and its polymorph [Bi6{FeO4@Fe12O12(OH)10(H2O)2}(μ-O2CCF3)10](3+) (3). These results are contrasted with the exchange interactions present in the previously characterized [Fe6(OH)3Ge2W18O68(OH)6](11-) and [H12As4Fe8W30O120(H2O)2](4-) anions. The computational analysis shows that the most significant antiferromagnetic spin coupling takes place at the junction between each of the {Fe3O6(OH)3}/{Fe3F6(OCH3)3} framework motifs, a possibility that had been previously discarded in the literature on the basis of the Fe-Fe distances. For all the examined iron(III) Keggin structures, it is found that the magnitude of the magnetic couplings within each structural subunit follows the same trend.

  8. Engineering and Design: Composite Materials for Civil Engineering Structures

    DTIC Science & Technology

    1997-03-31

    plan should include appropriate funds and schedule for this special design effort, including appropri- ate expert consultation. A reliable quality...assurance plan is essential for design, fabrication, and erection. To ensure acceptability of the final product, specific verifica- tion, testing, and...structural applications, the design engineer must develop a more thorough quality assurance plan , sufficient to verify the adequacy of the FRP in

  9. Semiconductor alloys - Structural property engineering

    NASA Technical Reports Server (NTRS)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  10. Designing, engineering, and testing wood structures

    NASA Technical Reports Server (NTRS)

    Gorman, Thomas M.

    1992-01-01

    The objective of this paper is to introduce basic structural engineering concepts in a clear, simple manner while actively involving students. This project emphasizes the fact that a good design uses materials efficiently. The test structure in this experiment can easily be built and has various design options. Even when the structure is loaded to collapsing, only one or two pieces usually break, leaving the remaining pieces intact and reusable.

  11. The flexible pocketome engine for structural chemogenomics.

    PubMed

    Abagyan, Ruben; Kufareva, Irina

    2009-01-01

    Biological metabolites, substrates, cofactors, chemical probes, and drugs bind to flexible pockets in multiple biological macromolecules to exert their biological effect. The rapid growth of the structural databases and sequence data, including SNPs and disease-related genome modifications, complemented by the new cutting-edge 3D docking, scoring, and profiling methods has created a unique opportunity to develop a comprehensive structural map of interactions between any small molecule and biopolymers. Here we demonstrate that a comprehensive structural genomics engine can be built using multiple pocket conformations, experimentally determined or generated with a variety of modeling methods, and new efficient ensemble docking algorithms. In contrast to traditional ligand-activity-based engines trained on known chemical structures and their activities, the structural pocketome and docking engine will allow prediction of poses and activities for new, previously unknown, protein binding sites, and new, previously uncharacterized, chemical scaffolds. This de novo structure-based activity prediction engine may dramatically accelerate the discovery of potent and specific therapeutics with reduced side effects.

  12. The Structure of Galaxies. III. Two Structural Families of Ellipticals

    NASA Astrophysics Data System (ADS)

    Schombert, James M.

    2015-11-01

    Using isophotal radius correlations for a sample of Two Micron All Sky Survey ellipticals, we have constructed a series of template surface brightness profiles to describe the profile shapes of ellipticals as a function of luminosity. The templates are a smooth function of luminosity, yet are not adequately matched to any fitting function supporting the view that ellipticals are weakly nonhomologous with respect to structure. Through comparison to the templates, it is discovered that ellipticals are divided into two families: those well matched to the templates, and a second class of ellipticals with distinctly shallower profile slopes. We refer to this second type of ellipticals as D class, an old morphological designation acknowledging diffuse appearance on photographic material. D ellipticals cover the same range of luminosity, size, and kinematics as normal ellipticals, but maintain a signature of recent equal-mass dry mergers. We propose that normal ellipticals grow after an initial dissipation formation era by accretion of low-mass companions as outlined in hierarchical formation scenarios, while D ellipticals are the result of later equal-mass mergers producing shallow luminosity profiles.

  13. Engineered biosynthesis of plant polyketides: chain length control in an octaketide-producing plant type III polyketide synthase.

    PubMed

    Abe, Ikuro; Oguro, Satoshi; Utsumi, Yoriko; Sano, Yukie; Noguchi, Hiroshi

    2005-09-14

    The chalcone synthase (CHS) superfamily of type III polyketide synthases (PKSs) produces a variety of plant secondary metabolites with remarkable structural diversity and biological activities (e.g., chalcones, stilbenes, benzophenones, acrydones, phloroglucinols, resorcinols, pyrones, and chromones). Here we describe an octaketide-producing novel plant-specific type III PKS from aloe (Aloe arborescens) sharing 50-60% amino acid sequence identity with other plant CHS-superfamily enzymes. A recombinant enzyme expressed in Escherichia coli catalyzed seven successive decarboxylative condensations of malonyl-CoA to yield aromatic octaketides SEK4 and SEK4b, the longest polyketides known to be synthesized by the structurally simple type III PKS. Surprisingly, site-directed mutagenesis revealed that a single residue Gly207 (corresponding to the CHS's active site Thr197) determines the polyketide chain length and product specificity. Small-to-large substitutions (G207A, G207T, G207M, G207L, G207F, and G207W) resulted in loss of the octaketide-forming activity and concomitant formation of shorter chain length polyketides (from triketide to heptaketide) including a pentaketide chromone, 2,7-dihydroxy-5-methylchromone, and a hexaketide pyrone, 6-(2,4-dihydroxy-6-methylphenyl)-4-hydroxy-2-pyrone, depending on the size of the side chain. Notably, the functional diversity of the type III PKS was shown to evolve from simple steric modulation of the chemically inert single residue lining the active-site cavity accompanied by conservation of the Cys-His-Asn catalytic triad. This provided novel strategies for the engineered biosynthesis of pharmaceutically important plant polyketides.

  14. 14 CFR 33.23 - Engine mounting attachments and structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine mounting attachments and structure... mounting attachments and structure. (a) The maximum allowable limit and ultimate loads for engine mounting attachments and related engine structure must be specified. (b) The engine mounting attachments and...

  15. 1,2,4-Diazaphospholide complexes of lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii): synthesis, X-ray structural characterization, and magnetic susceptibility studies.

    PubMed

    Zhao, Minggang; Wang, Lixia; Li, Pangpang; Ma, Jianping; Zheng, Wenjun

    2016-07-05

    A few heteroleptic, charge-separated heterobimetallic, and polymeric alkali metalate complexes of 1,2,4-diazaphospholide lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii) were simply prepared via the metathesis reaction of MCl3 (THF)m (m = 1-2) and K[3,5-R2dp] ([3,5-R2dp](-) = 3,5-di-substituent-1,2,4-diazaphospholide; R = tBu, Ph) in a varied ratio (1 : 3, 1 : 4, and 1 : 5, respectively) at room temperature in tetrahydrofuran. All the complexes were fully characterized by (1)H, (13)C{(1)H}, (31)P{(1)H}, IR, and X-ray single crystal diffraction analysis despite their paramagnetism (excluding La(iii) complexes). The structures of the complexes were found to feature varied coordination modes. The magnetic properties of several compounds were studied by magnetic susceptibility, and the complexes presented the magnetic moments close to or lower than the theoretical values for the free ions in the trivalent oxidation states (Pr(3+), Nd(3+)).

  16. Structures of engineered Clostridium botulinum neurotoxin derivatives

    PubMed Central

    Masuyer, Geoffrey; Stancombe, Patrick; Chaddock, John A.; Acharya, K. Ravi

    2011-01-01

    Targeted secretion inhibitors (TSIs) are a new class of engineered biopharmaceutical molecules derived from the botulinum neurotoxins (BoNTs). They consist of the metalloprotease light chain (LC) and translocation domain (Hn) of BoNT; they thus lack the native toxicity towards motor neurons but are able to target soluble N-ethylmaleimide-sensitive fusion protein attachment receptor (SNARE) proteins. These functional fragment (LHn) derivatives are expressed as single-chain proteins and require post-translational activation into di-chain molecules for function. A range of BoNT derivatives have been produced to demonstrate the successful use of engineered SNARE substrate peptides at the LC–Hn interface that gives these molecules self-activating capabilities. Alternatively, recognition sites for specific exoproteases can be engineered to allow controlled activation. Here, the crystal structures of three LHn derivatives are reported between 2.7 and 3.0 Å resolution. Two of these molecules are derivatives of serotype A that contain a SNARE peptide. Additionally, a third structure corresponds to LHn serotype B that includes peptide linkers at the exoprotease activation site. In all three cases the added engineered segments could not be modelled owing to disorder. However, these structures highlight the strong interactions holding the LHn fold together despite the inclusion of significant polypeptide sequences at the LC–Hn interface. PMID:22139146

  17. Soy-Based, Water-Cooled, TC W-III Two Cycle Engine Oil

    SciTech Connect

    Scharf, Curtis R.; Miller, Mark E.

    2003-08-30

    The objective of this project was to achieve technical approval and commercial launch for a biodegradable soy oil-based, environmentally safe, TC W-III performance, water-cooled, two cycle engine oil. To do so would: (1) develop a new use for RBD soybean oil; (2) increase soybean utilization in North America in the range of 500 K-3.0 MM bushels; and (3) open up supply opportunities of 1.5-5.0 MM bushels worldwide. These goals have been successfully obtained.

  18. Biomimetic electrospun nanofibrous structures for tissue engineering

    PubMed Central

    Wang, Xianfeng; Ding, Bin; Li, Bingyun

    2013-01-01

    Biomimetic nanofibrous scaffolds mimicking important features of the native extracellular matrix provide a promising strategy to restore functions or achieve favorable responses for tissue regeneration. This review provides a brief overview of current state-of-the-art research designing and using biomimetic electrospun nanofibers as scaffolds for tissue engineering. It begins with a brief introduction of electrospinning and nanofibers, with a focus on issues related to the biomimetic design aspects. The review next focuses on several typical biomimetic nanofibrous structures (e.g. aligned, aligned to random, spiral, tubular, and sheath membrane) that have great potential for tissue engineering scaffolds, and describes their fabrication, advantages, and applications in tissue engineering. The review concludes with perspectives on challenges and future directions for design, fabrication, and utilization of scaffolds based on electrospun nanofibers. PMID:25125992

  19. The Structure and Function of Type III Secretion Systems

    PubMed Central

    Notti, Ryan Q.; Stebbins, C. Erec

    2015-01-01

    ARTICLE SUMMARY Type III secretion systems (T3SS) afford gram-negative bacteria a most intimate means of altering the biology of their eukaryotic hosts — the direct delivery of effector proteins from the bacterial cytoplasm to that of the eukaryote. This incredible biophysical feat is accomplished by nanosyringe “injectisomes,” which form a conduit across the three plasma membranes, peptidoglycan layer and extracellular space that form a barrier to the direct delivery of proteins from bacterium to host. The focus of this chapter is T3SS function at the structural level; we will summarize the core findings that have shaped our understanding of the structure and function of these systems and highlight recent developments in the field. In turn, we describe the T3SS secretory apparatus, consider its engagement with secretion substrates, and discuss the post-translational regulation of secretory function. Lastly, we close with a discussion of the future prospects for the interrogation of structure-function relationships in the T3SS. PMID:26999392

  20. Gallium(III) Tetraphenylporphyrinates Containing Hydrosulfide and Thiolate Ligands: Structural Models for Sulfur-Bound Iron(III) Hemes.

    PubMed

    Meininger, Daniel J; Chee-Garza, Max; Arman, Hadi D; Tonzetich, Zachary J

    2016-03-07

    Gallium(III) tetraphenylporphyrinates (TPP) containing anionic sulfur ligands have been prepared and characterized in the solid state and solution. The complexes serve as structural models for iron(III) heme sites containing sulfur coordination that otherwise prove challenging to synthesize due to the propensity for reduction to iron(II). The compounds prepared include the first well-characterized example of a trivalent metalloporphyrinate containing a terminal hydrosulfide ligand, [Ga(SH)(TPP)], as well as [Ga(SEt)(TPP)], [Ga(SPh)(TPP)], and [Ga(SSi(i)Pr3)(TPP)]. The stability of these compounds toward reduction has permitted an investigation of their solid-state structures and electrochemistry. The structural features and reaction chemistry of the complexes in relation to their iron(III) analogs is discussed.

  1. Structural and functional characterization of two unusual endonuclease III enzymes from Deinococcus radiodurans.

    PubMed

    Sarre, Aili; Ökvist, Mats; Klar, Tobias; Hall, David R; Smalås, Arne O; McSweeney, Sean; Timmins, Joanna; Moe, Elin

    2015-08-01

    While most bacteria possess a single gene encoding the bifunctional DNA glycosylase Endonuclease III (EndoIII) in their genomes, Deinococcus radiodurans possesses three: DR2438 (DrEndoIII1), DR0289 (DrEndoIII2) and DR0982 (DrEndoIII3). Here we have determined the crystal structures of DrEndoIII1 and an N-terminally truncated form of DrEndoIII3 (DrEndoIII3Δ76). We have also generated a homology model of DrEndoIII2 and measured activity of the three enzymes. All three structures consist of two all α-helical domains, one of which exhibits a [4Fe-4S] cluster and the other a HhH-motif, separated by a DNA binding cleft, similar to previously determined structures of endonuclease III from Escherichia coli and Geobacillus stearothermophilus. However, both DrEndoIII1 and DrEndoIII3 possess an extended HhH motif with extra helical features and an altered electrostatic surface potential. In addition, the DNA binding cleft of DrEndoIII3 seems to be less accessible for DNA interactions, while in DrEndoIII1 it seems to be more open. Analysis of the enzyme activities shows that DrEndoIII2 is most similar to the previously studied enzymes, while DrEndoIII1 seems to be more distant with a weaker activity towards substrate DNA containing either thymine glycol or an abasic site. DrEndoIII3 is the most distantly related enzyme and displays no detectable activity towards these substrates even though the suggested catalytic residues are conserved. Based on a comparative structural analysis, we suggest that the altered surface potential, shape of the substrate-binding pockets and specific amino acid substitutions close to the active site and in the DNA interacting loops may underlie the unexpected differences in activity.

  2. Chemistry Characterization of Jet Aircraft Engine Particulate by XPS: Results from APEX III

    NASA Technical Reports Server (NTRS)

    Vander Wal, Randy L.; Bryg, Victoria M.

    2014-01-01

    This paper reports XPS analysis of jet exhaust particulate from a B737, Lear, ERJ, and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and platforms. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20 percent or more. By lower resolution survey scans various elements including transition metals are identified along with lighter elements such as S, N, and O in the form of oxides. Burning additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their presence can be used as a tracer for identifying soots from aircraft engines as well as diagnostic for monitoring engine performance and wear.

  3. Chemistry characterization of jet aircraft engine particulate matter by XPS: Results from APEX III

    NASA Astrophysics Data System (ADS)

    Vander Wal, Randy L.; Bryg, Victoria M.; Huang, Chung-Hsuan

    2016-09-01

    This paper reports X-ray photoelectron spectroscopy (XPS) analysis of jet exhaust particulate matter (PM) from a B737, Lear, ERJ and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and powers. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20% or more. By survey scans various elements including transition metals are identified along with lighter elements such as S, N and O in the form of oxides. Additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their collective presence could serve as an environmental tracer for identifying PM originating from aircraft engines and serving as a diagnostic for engine performance and wear.

  4. Assembly, structure, function and regulation of type III secretion systems.

    PubMed

    Deng, Wanyin; Marshall, Natalie C; Rowland, Jennifer L; McCoy, James M; Worrall, Liam J; Santos, Andrew S; Strynadka, Natalie C J; Finlay, B Brett

    2017-04-10

    Type III secretion systems (T3SSs) are protein transport nanomachines that are found in Gram-negative bacterial pathogens and symbionts. Resembling molecular syringes, T3SSs form channels that cross the bacterial envelope and the host cell membrane, which enable bacteria to inject numerous effector proteins into the host cell cytoplasm and establish trans-kingdom interactions with diverse hosts. Recent advances in cryo-electron microscopy and integrative imaging have provided unprecedented views of the architecture and structure of T3SSs. Furthermore, genetic and molecular analyses have elucidated the functions of many effectors and key regulators of T3SS assembly and secretion hierarchy, which is the sequential order by which the protein substrates are secreted. As essential virulence factors, T3SSs are attractive targets for vaccines and therapeutics. This Review summarizes our current knowledge of the structure and function of this important protein secretion machinery. A greater understanding of T3SSs should aid mechanism-based drug design and facilitate their manipulation for biotechnological applications.

  5. Identification of protein structural elements responsible for the diversity of sequence preferences among Mini-III RNases

    PubMed Central

    Głów, Dawid; Kurkowska, Małgorzata; Czarnecka, Justyna; Szczepaniak, Krzysztof; Pianka, Dariusz; Kappert, Verena; Bujnicki, Janusz M.; Skowronek, Krzysztof J.

    2016-01-01

    Many known endoribonucleases select their substrates based on the presence of one or a few specific nucleotides at or near the cleavage site. In some cases, selectivity is also determined by the structural features of the substrate. We recently described the sequence-specific cleavage of double-stranded RNA by Mini-III RNase from Bacillus subtilis in vitro. Here, we characterized the sequence specificity of eight other members of the Mini-III RNase family from different bacterial species. High-throughput analysis of the cleavage products of Φ6 bacteriophage dsRNA indicated subtle differences in sequence preference between these RNases, which were confirmed and characterized by systematic analysis of the cleavage kinetics of a set of short dsRNA substrates. We also showed that the sequence specificities of Mini-III RNases are not reflected by different binding affinities for cognate and non-cognate sequences, suggesting that target selection occurs predominantly at the cleavage step. We were able to identify two structural elements, the α4 helix and α5b-α6 loop that were involved in target selection. Characterization of the sequence specificity of the eight Mini-III RNases may provide a basis for better understanding RNA substrate recognition by Mini-III RNases and adopting these enzymes and their engineered derivatives as tools for RNA research. PMID:27924926

  6. Identification of protein structural elements responsible for the diversity of sequence preferences among Mini-III RNases.

    PubMed

    Głów, Dawid; Kurkowska, Małgorzata; Czarnecka, Justyna; Szczepaniak, Krzysztof; Pianka, Dariusz; Kappert, Verena; Bujnicki, Janusz M; Skowronek, Krzysztof J

    2016-12-07

    Many known endoribonucleases select their substrates based on the presence of one or a few specific nucleotides at or near the cleavage site. In some cases, selectivity is also determined by the structural features of the substrate. We recently described the sequence-specific cleavage of double-stranded RNA by Mini-III RNase from Bacillus subtilis in vitro. Here, we characterized the sequence specificity of eight other members of the Mini-III RNase family from different bacterial species. High-throughput analysis of the cleavage products of Φ6 bacteriophage dsRNA indicated subtle differences in sequence preference between these RNases, which were confirmed and characterized by systematic analysis of the cleavage kinetics of a set of short dsRNA substrates. We also showed that the sequence specificities of Mini-III RNases are not reflected by different binding affinities for cognate and non-cognate sequences, suggesting that target selection occurs predominantly at the cleavage step. We were able to identify two structural elements, the α4 helix and α5b-α6 loop that were involved in target selection. Characterization of the sequence specificity of the eight Mini-III RNases may provide a basis for better understanding RNA substrate recognition by Mini-III RNases and adopting these enzymes and their engineered derivatives as tools for RNA research.

  7. Fatigue Reliability of Gas Turbine Engine Structures

    NASA Technical Reports Server (NTRS)

    Cruse, Thomas A.; Mahadevan, Sankaran; Tryon, Robert G.

    1997-01-01

    The results of an investigation are described for fatigue reliability in engine structures. The description consists of two parts. Part 1 is for method development. Part 2 is a specific case study. In Part 1, the essential concepts and practical approaches to damage tolerance design in the gas turbine industry are summarized. These have evolved over the years in response to flight safety certification requirements. The effect of Non-Destructive Evaluation (NDE) methods on these methods is also reviewed. Assessment methods based on probabilistic fracture mechanics, with regard to both crack initiation and crack growth, are outlined. Limit state modeling techniques from structural reliability theory are shown to be appropriate for application to this problem, for both individual failure mode and system-level assessment. In Part 2, the results of a case study for the high pressure turbine of a turboprop engine are described. The response surface approach is used to construct a fatigue performance function. This performance function is used with the First Order Reliability Method (FORM) to determine the probability of failure and the sensitivity of the fatigue life to the engine parameters for the first stage disk rim of the two stage turbine. A hybrid combination of regression and Monte Carlo simulation is to use incorporate time dependent random variables. System reliability is used to determine the system probability of failure, and the sensitivity of the system fatigue life to the engine parameters of the high pressure turbine. 'ne variation in the primary hot gas and secondary cooling air, the uncertainty of the complex mission loading, and the scatter in the material data are considered.

  8. Solvation structure and thermodynamics for Pr(III), Nd(III) and Dy(III) complexes in ionic liquids evaluated by Raman spectroscopy and DFT calculation

    NASA Astrophysics Data System (ADS)

    Kuribara, Keita; Matsumiya, Masahiko; Tsunashima, Katsuhiko

    2016-12-01

    package. The bonding energy, ΔEb, was calculated as ΔEb = Etot(cluster) - Etot(RE3+) - nEtot([TFSA]-), and ΔEb ([Pr(III)(cis-TFSA)5]2-), ΔEb([Nd(III)(cis-TFSA)5]2-), and ΔEb([Dy(III)(cis-TFSA)5]2-) were calculated to be -4238.6 ± 6.8, -4362.3 ± 8.2, and -4284.2 ± 7.4 kJ mol-1, respectively. This series of structural results allows us to conclude that [Dy(III)(cis-TFSA)5]2- clusters are more stable state than the [Pr(III)(cis-TFSA)5]2- clusters in [P2225][TFSA]. Furthermore, the average atomic charges and the bond distances of these clusters were consistent with the thermodynamic properties.

  9. Cylinder head structure for internal combustion engines

    SciTech Connect

    Taguchi, T.; Takata, Y.; Tanaka, Y.

    1986-02-04

    This patent describes an engine cylinder head structure including a top wall formed with camshaft bearings, a bottom wall adapted to be attached to a cylinder block, and side walls connecting the top and bottom walls together. It also includes a cooling watter passage defined by the top, bottom and side walls, a transversely extending reinforcement rib formed in the top wall to project into the cooling water passage beneath each of the camshaft bearings and to extend between and interconnect the side walls.

  10. IMPROVEMENT TO PIPELINE COMPRESSOR ENGINE RELIABILITY THROUGH RETROFIT MICRO-PILOT IGNITION SYSTEM -- PHASE III

    SciTech Connect

    Scott Chase; Daniel Olsen; Ted Bestor

    2005-03-01

    This report documents the third year's effort towards a 3-year program conducted by the Engines & Energy Conversion Laboratory (EECL) at Colorado State University (CSU) to develop micropilot ignition systems for existing pipeline compressor engines. Research activities for the overall program were conducted with the understanding that the efforts are to result in a commercial product to capture and disseminate the efficiency and environmental benefits of this new technology. Commercially-available fuel injection products were identified and applied to the program where appropriate. This approach will minimize the overall time-to-market requirements, while meeting performance and cost criteria. Two earlier phases of development precede this report. The objective for Phase I was to demonstrate the feasibility of retrofit micropilot ignition (RMI) systems for large bore, slow speed engines operating at low compression ratios under laboratory conditions at the EECL. The objective for Phase II was to further develop and optimize the micropilot ignition system at the EECL for large bore, slow speed engines operating at low compression ratios. These laboratory results were enhanced, then verified via a field demonstration project during Phase III of the Micropilot Ignition program. An Implementation Team of qualified engine retrofit service providers was assembled to install the retrofit micropilot ignition system for an engine operated by El Paso Pipeline Group at a compressor station near Window Rock, Arizona. Testing of this demonstration unit showed that the same benefits identified by laboratory testing at CSU, i.e., reduced fuel consumption and exhaust emissions (NOx, THC, CO, and CH2O). Installation efforts at Window Rock were completed towards the end of the budget period, which did not leave sufficient time to complete the durability testing. These efforts are ongoing, with funding provided by El Paso Pipeline Group, and the results will be documented in a report

  11. Structural Engineering Managers - Innovation Challenges for their Skills

    NASA Astrophysics Data System (ADS)

    Linkeschová, D.; Tichá, A.

    2015-11-01

    The profession of a structural engineer is highly responsible, because the consequences of a structural engineer's errors result not only in economic damage to the property and often irreversible damage to the environment, they can also lead to direct loss of lives. In the current turbulent, dynamically developing society the managerial methods of structural engineers should not stagnate at the level of the last century applications. This paper deals with the challenges which the ongoing century poses to structural engineers and managers. It compares the results of research regarding the current state of managerial skills of structural engineers in Czech building companies to the defined skills of the 21st century's managers according to the global research programme ITL Research and according to the Vision for the Future of Structural Engineering, drawn up by Structural Engineering Institute - SEI ASCE.

  12. Structural influences on the exchange coupling and zero-field splitting in the single-molecule magnet [Mn(III)6Mn(III)]3+.

    PubMed

    Hoeke, Veronika; Heidemeier, Maik; Krickemeyer, Erich; Stammler, Anja; Bögge, Hartmut; Schnack, Jürgen; Glaser, Thorsten

    2012-11-07

    A comprehensive synthetic, structural, mass spectrometrical, FT-IR and UV/Vis spectroscopic, electrochemical, and magnetic study on [Mn(III)(6)Mn(III)](3+) (= [{(talen(t-Bu(2)))Mn(III)(3)}(2){Mn(III)(CN)(6)}](3+)) is presented. The high stability of [Mn(III)(6)Mn(III)](3+) in solution allows the preparation of different salts and solvates: [Mn(III)(6)Mn(III)](BPh(4))(3)·3MeOH·3MeCN·3Et(2)O (), [Mn(III)(6)Mn(III)(MeOH)(4)](BPh(4))(3)·5MeOH (), [Mn(III)(6)Mn(III)(MeOH)(6)](BF(4))(3)·9MeOH (), [Mn(III)(6)Mn(III)(MeOH)(6)](PF(6))(2)(OAc)·11MeOH (), and [Mn(III)(6)Mn(III)(MeOH)(6)](lactate)(3)·5MeOH·10H(2)O (). The molecular structure of [Mn(III)(6)Mn(III)](3+) is closely related to the already published [Mn(III)(6)M(c)](3+) complexes (M(c) = Cr(III), Fe(III), Co(III)). ESI mass spectra exhibit the signal of the [{(talen(t-Bu(2)))Mn(III)(3)}(2){Mn(III)(CN)(6)}](3+) trication. FT-IR spectra show the characteristic bands of the triplesalen ligand in [Mn(III)(6)M(c)](3+) and the symmetric ν(C≡N) vibration of the [Mn(III)(CN)(6)](3-) unit at 2135 cm(-1). UV/Vis spectra are dominated by intense transitions of the trinuclear Mn(III)(3) triplesalen subunits above 20,000 cm(-1). The electrochemical studies establish the occurrence of ligand-centered oxidations at ≈1.0 V vs. Fc(+)/Fc, an oxidation of the central Mn(III) at 0.78 V, and a series of reductions of the terminal Mn(III) ions between -0.6 and -1.2 V. AC magnetic measurements indicate single-molecule magnet (SMM) behavior for all compounds. The DC magnetic data are analyzed by a full-matrix diagonalization of the appropriate spin-Hamiltonian including isotropic exchange, zero-field splitting with full consideration of the relative orientation of the D-tensors, and Zeeman interaction, taking into account the diamagnetic nature of the central Mn(III) at low temperatures as inferred from a previous ab initio study. The spin-Hamiltonian simulations indicate Mn(III)-Mn(III) interactions in the -0.37 to -0.70 cm

  13. THE CRYSTAL STRUCTURE OF ANTIMONY (III) SULFOBROMIDE, SBSBR,

    DTIC Science & Technology

    ANTIMONY COMPOUNDS, *SULFUR COMPOUNDS, CRYSTAL STRUCTURE , CRYSTAL STRUCTURE , BROMIDES, SYMMETRY(CRYSTALLOGRAPHY), FOURIER ANALYSIS, MOLECULAR STRUCTURE, CRYSTAL LATTICES, CHEMICAL BONDS, X RAY DIFFRACTION.

  14. Investigating the Structure of the WJ-III Cognitive at School Age

    ERIC Educational Resources Information Center

    Dombrowski, Stefan C.

    2013-01-01

    During its development, the Woodcock-Johnson, Third Edition Cognitive (WJ-III Cognitive; McGrew & Woodcock, 2001) was never subjected to structural analysis using exploratory and higher order factor analyses. Instead, confirmatory factor analyses were conducted on separate sets of WJ-III correlation matrices, yielding a seven-factor model…

  15. Crystal structures of salicylideneguanylhydrazinium chloride and its copper(II) and cobalt(III) chloride complexes

    SciTech Connect

    Chumakov, Yu. M. Tsapkov, V. I.; Bocelli, G.; Antosyak, B. Ya.; Shova, S. G.; Gulea, A. P.

    2006-01-15

    The crystal structures of salicylideneguanylhydrazinium chloride hydrate hemiethanol solvate (I), salicylideneguanylhydrazinium trichloroaquacuprate(II) (II), and bis(salicylideneguanylhydrazino)cobalt(III) chloride trihydrate (III) are determined using X-ray diffraction. The structures of compounds I, II, and III are solved by direct methods and refined using the least-squares procedure in the anisotropic approximation for the non-hydrogen atoms to the final factors R = 0.0597, 0.0212, and 0.0283, respectively. In the structure of compound I, the monoprotonated molecules and chlorine ions linked by hydrogen bonds form layers aligned parallel to the (010) plane. In the structure of compound II, the salicylaldehyde guanylhydrazone cations and polymer chains consisting of trichloroaquacuprate(II) anions are joined by an extended three-dimensional network of hydrogen bonds. In the structure of compound III, the [Co(LH){sub 2}]{sup +} cations, chloride ions, and molecules of crystallization water are linked together by a similar network.

  16. Structure of cellular ESCRT-III spirals and their relationship to HIV budding.

    PubMed

    Cashikar, Anil G; Shim, Soomin; Roth, Robyn; Maldazys, Michael R; Heuser, John E; Hanson, Phyllis I

    2014-05-30

    The ESCRT machinery along with the AAA+ ATPase Vps4 drive membrane scission for trafficking into multivesicular bodies in the endocytic pathway and for the topologically related processes of viral budding and cytokinesis, but how they accomplish this remains unclear. Using deep-etch electron microscopy, we find that endogenous ESCRT-III filaments stabilized by depleting cells of Vps4 create uniform membrane-deforming conical spirals which are assemblies of specific ESCRT-III heteropolymers. To explore functional roles for ESCRT-III filaments, we examine HIV-1 Gag-mediated budding of virus-like particles and find that depleting Vps4 traps ESCRT-III filaments around nascent Gag assemblies. Interpolating between the observed structures suggests a new role for Vps4 in separating ESCRT-III from Gag or other cargo to allow centripetal growth of a neck constricting ESCRT-III spiral.

  17. Structural Basis for Substrate Binding and the Catalytic Mechanism of Type III Pantothenate Kinase

    SciTech Connect

    Yang, Kun; Strauss, Erick; Huerta, Carlos; Zhang, Hong

    2008-07-15

    Pantothenate kinase (PanK) catalyzes the first step of the universal five-step coenzyme A (CoA) biosynthetic pathway. The recently characterized type III PanK (PanK-III, encoded by the coaX gene) is distinct in sequence, structure and enzymatic properties from both the long-known bacterial type I PanK (PanK-I, exemplified by the Escherichia coli CoaA protein) and the predominantly eukaryotic type II PanK (PanK-II). PanK-III enzymes have an unusually high K{sub m} for ATP, are resistant to feedback inhibition by CoA, and are unable to utilize the N-alkylpantothenamide family of pantothenate analogues as alternative substrates, thus making type III PanK ineffective in generating CoA analogues as antimetabolites in vivo. Previously, we reported the crystal structure of the PanK-III from Thermotoga maritima and identified it as a member of the 'acetate and sugar kinase/heat shock protein 70/actin' (ASKHA) superfamily. Here we report the crystal structures of the same PanK-III in complex with one of its substrates (pantothenate), its product (phosphopantothenate) as well as a ternary complex structure of PanK-III with pantothenate and ADP. These results are combined with isothermal titration calorimetry experiments to present a detailed structural and thermodynamic characterization of the interactions between PanK-III and its substrates ATP and pantothenate. Comparison of substrate binding and catalytic sites of PanK-III with that of eukaryotic PanK-II revealed drastic differences in the binding modes for both ATP and pantothenate substrates, and suggests that these differences may be exploited in the development of new inhibitors specifically targeting PanK-III.

  18. Rhombus-shaped tetranuclear [Ln4] complexes [Ln = Dy(III) and Ho(III)]: synthesis, structure, and SMM behavior.

    PubMed

    Chandrasekhar, Vadapalli; Hossain, Sakiat; Das, Sourav; Biswas, Sourav; Sutter, Jean-Pascal

    2013-06-03

    The reaction of a new hexadentate Schiff base hydrazide ligand (LH3) with rare earth(III) chloride salts in the presence of triethylamine as the base afforded two planar tetranuclear neutral complexes: [{(LH)2Dy4}(μ2-O)4](H2O)8·2CH3OH·8H2O (1) and [{(LH)2Ho4}(μ2-O)4](H2O)8·6CH3OH·4H2O (2). These neutral complexes possess a structure in which all of the lanthanide ions and the donor atoms of the ligand remain in a perfect plane. Each doubly deprotonated ligand holds two Ln(III) ions in its two distinct chelating coordination pockets to form [LH(Ln)2](4+) units. Two such units are connected by four [μ2-O](2-) ligands to form a planar tetranuclear assembly with an Ln(III)4 core that possesses a rhombus-shaped structure. Detailed static and dynamic magnetic analysis of 1 and 2 revealed single-molecule magnet (SMM) behavior for complex 1. A peculiar feature of the χM" versus temperature curve is that two peaks that are frequency-dependent are revealed, indicating the occurrence of two relaxation processes that lead to two energy barriers (16.8 and 54.2 K) and time constants (τ0 = 1.4 × 10(-6) s, τ0 = 7.2 × 10(-7) s). This was related to the presence of two distinct geometrical sites for Dy(III) in complex 1.

  19. Strain-engineered novel III-N electronic devices with high quality dielectric/semiconductor interfaces

    NASA Astrophysics Data System (ADS)

    Khan, M. Asif; Shur, M. S.; Simin, G.

    2003-11-01

    over AlGaN with low interface state densities. They have then been used to demonstrate III-N insulating gate transistors (MOSHFET (SiO2) and MISHFET (Si3N4) with gate leakage currents 4-6 order less than those for conventional GaN-AlGaN HFETs. The introduction of the thin insulator layers (less then 100 Å) under the gate increases the threshold voltage by 2-3 V. In addition, it reduces the peak transconductance gm. However the unity cut-off frequency, the gain and the rf-powers remain unaffected as the gm/Cgs (gate-source capacitance) ratio remains unchanged. In addition to managing the defects and gate leakage currents we have also employed InGaN channel double heterojunction structures (AlInGaN-InGaN-GaN) to confine the carriers thereby reducing the spillover into trappings states. These InGaN based MOS-DHFETs exhibited no current-collapse, extremely low gate leakage currents (<10-10 A/mm) and 10-26 GHz rf-powers in excess of 6 W/mm. We have also demonstrated the scalability and stable operation of our new and innovative InGaN based insulating gate heterojunction field effect transistor approach. In this paper we will review the III-N heterojunction field-effect transistors progress and pioneering innovations including the excellent work from several research groups around the world. (

  20. Effects of Humidity on Non-Hermetically Packaged III-V Structures and Devices

    NASA Technical Reports Server (NTRS)

    Leon, R.; Martin, S.; Lee, T.; Okuno, J.; Ruiz, R.; Gauldin, R.; Gaidis, M.; Smith, R.

    1999-01-01

    High humidity and temperature test (known as 85/85 tests) were performed on various III-V devices and structures to determine environmental effects in non-hermetically packaged GaAs membrane mixer diodes.

  1. Structure and interactions of fish type III antifreeze protein in solution.

    PubMed

    Salvay, Andrés G; Gabel, Frank; Pucci, Bernard; Santos, Javier; Howard, Eduardo I; Ebel, Christine

    2010-07-21

    It has been suggested that above a critical protein concentration, fish Type III antifreeze protein (AFP III) self-assembles to form micelle-like structures that may play a key role in antifreeze activity. To understand the complex activity of AFP III, a comprehensive description of its association state and structural organization in solution is necessary. We used analytical ultracentrifugation, analytical size-exclusion chromatography, and dynamic light scattering to characterize the interactions and homogeneity of AFP III in solution. Small-angle neutron scattering was used to determine the low-resolution structure in solution. Our results clearly show that at concentrations up to 20 mg mL(-1) and at temperatures of 20 degrees C, 6 degrees C, and 4 degrees C, AFP III is monomeric in solution and adopts a structure compatible with that determined by crystallography. Surface tension measurements show a propensity of AFP III to localize at the air/water interface, but this surface activity is not correlated with any aggregation in the bulk. These results support the hypothesis that each AFP III molecule acts independently of the others, and that specific intermolecular interactions between monomers are not required for binding to ice. The lack of attractive interactions between monomers may be functionally important, allowing for more efficient binding and covering of the ice surface.

  2. Structure and Interactions of Fish Type III Antifreeze Protein in Solution

    PubMed Central

    Salvay, Andrés G.; Gabel, Frank; Pucci, Bernard; Santos, Javier; Howard, Eduardo I.; Ebel, Christine

    2010-01-01

    Abstract It has been suggested that above a critical protein concentration, fish Type III antifreeze protein (AFP III) self-assembles to form micelle-like structures that may play a key role in antifreeze activity. To understand the complex activity of AFP III, a comprehensive description of its association state and structural organization in solution is necessary. We used analytical ultracentrifugation, analytical size-exclusion chromatography, and dynamic light scattering to characterize the interactions and homogeneity of AFP III in solution. Small-angle neutron scattering was used to determine the low-resolution structure in solution. Our results clearly show that at concentrations up to 20 mg mL−1 and at temperatures of 20°C, 6°C, and 4°C, AFP III is monomeric in solution and adopts a structure compatible with that determined by crystallography. Surface tension measurements show a propensity of AFP III to localize at the air/water interface, but this surface activity is not correlated with any aggregation in the bulk. These results support the hypothesis that each AFP III molecule acts independently of the others, and that specific intermolecular interactions between monomers are not required for binding to ice. The lack of attractive interactions between monomers may be functionally important, allowing for more efficient binding and covering of the ice surface. PMID:20643081

  3. Lanthanide ion probes of structure in biology. Environmentally sensitive fine structure in laser-induced terbium(III) luminescence.

    PubMed

    Sudnick, D R; Horrocks, W D

    1979-05-23

    The 488 nm line of the CW argon ion laser provides a convenient visible source for the direct excitation of the emissive 5D4 state of the Tb(III) ion. Room temperature emission spectra of Tb(III) in a variety of environments have been examined under relatively high resolution. The samples studied include structurally well-characterized crystalline solids, model chelate complexes in solution and Tb(III) bound to the enzyme thermolysin and the protein parvalbumin. The fine structure in the emissions is caused by ligand field splittings of both ground and excited state J manifolds. These spectra provide signatures sensitive to the immediate coordination environment of the Tb(III) ion. Solid state/solution state structural comparisons are made. The emission fine structure reveal differences between the EF side calcium-binding sites of parvalbumin and the calcium site 1 of thermolysin.

  4. Advanced fabrication techniques for cooled engine structures

    NASA Technical Reports Server (NTRS)

    Buchmann, O. A.

    1978-01-01

    An improved design for regeneratively cooled engine structures was identified. This design uses photochemically machined (PCM) coolant passages. It permits the braze joint to be placed in a relatively cool area, remote from the critical hot face sheet. The geometry of the passages at the face sheet also minimizes stress concentration and, therefore, enhances the low cycle fatigue performance. The two most promising alloys identified for this application are Inconel 617 and Nickel 201. Inconel 617 was selected because it has excellent creep rupture properties, while Nickel 201 was selected because of its predicted good performance under low cycle fatigue loading. The fabrication of the PCM coolant passages in both Inconel 617 and Nickel 201 was successfully developed. During fabrication of Inconel 617, undesirable characteristics were observed in the braze joints. A development program to resolve this condition was undertaken and led to definition of an isothermal solidification process for joining Inconel 617 panels. This process produced joints which approach parent metal strength and homogeneity.

  5. 1. Photographic copy of engineering drawing showing structure of Test ...

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

    1. Photographic copy of engineering drawing showing structure of Test Stand 'B' (4215/E-16), also known as the 'Short Snorter.' California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering 'Structural Addition - Bldg. E-12, Edwards Test Station,' drawing no. E12/1-1, 8 August 1957. - Jet Propulsion Laboratory Edwards Facility, Test Stand B, Edwards Air Force Base, Boron, Kern County, CA

  6. Syntheses, structures, and spectroscopic properties of plutonium and americium phosphites and the redetermination of the ionic radii of Pu(III) and Am(III).

    PubMed

    Cross, Justin N; Villa, Eric M; Wang, Shuao; Diwu, Juan; Polinski, Matthew J; Albrecht-Schmitt, Thomas E

    2012-08-06

    A series of isotypic rare earth phosphites (RE = Ce(III), Pr(III), Nd(III), Pu(III), or Am(III)) with the general formulas RE(2)(HPO(3))(3)(H(2)O) along with a Pu(IV) phosphite, Pu[(HPO(3))(2)(H(2)O)(2)], have been prepared hydrothermally via reactions of RECl(3) with phosphorous acid. The structure of RE(2)(HPO(3))(3)(H(2)O) features a face-sharing interaction of eight- and nine-coordinate rare earth polyhedra. By use of the crystallographic data from the isotypic series along with data from previously reported isotypic series, the ionic radii for higher coordinate Pu(III) and Am(III) were calculated. The (VIII)Pu(III) radius was calculated as 1.112 ± 0.004 Å, and the (IX)Pu(III) radius was calculated to be 1.165 ± 0.002 Å. The (VIII)Am(III) radius was calculated as 1.108 ± 0.004 Å, and the (IX)Am(III) radius was calculated as 1.162 ± 0.002 Å.

  7. Engineering Property Prediction Tools for Tailored Polymer Composite Structures

    SciTech Connect

    Nguyen, Ba Nghiep; Foss, Peter; Wyzgoski, Michael; Trantina, Gerry; Kunc, Vlastimil; Schutte, Carol; Smith, Mark T.

    2009-12-23

    This report summarizes our FY 2009 research activities for the project titled:"Engineering Property Prediction Tools for Tailored Polymer Composite Structures." These activities include (i) the completion of the development of a fiber length attrition model for injection-molded long-fiber thermoplastics (LFTs), (ii) development of the a fatigue damage model for LFTs and its implementation in ABAQUS, (iii) development of an impact damage model for LFTs and its implementation in ABAQUS, (iv) development of characterization methods for fatigue testing, (v) characterization of creep and fatigue responses of glass-fiber/polyamide (PA6,6) and glass-fiber/polypropylene (PP), (vi) characterization of fiber length distribution along the flow length of glass/PA6,6 and glass-fiber/PP, and (vii) characterization of impact responses of glass-fiber/PA6,6. The fiber length attrition model accurately captures the fiber length distribution along the flow length of the studied glass-fiber/PP material. The fatigue damage model is able to predict the S-N and stiffness reduction data which are valuable to the fatigue design of LFTs. The impact damage model correctly captures damage accumulation observed in experiments of glass-fiber/PA6,6 plaques.Further work includes validations of these models for representative LFT materials and a complex LFT part.

  8. Engineering Encounters: Building a Spaghetti Structure

    ERIC Educational Resources Information Center

    Llewellyn, Douglas; Pray, Sandra; DeRose, Rob; Ottman, William

    2016-01-01

    This column presents ideas and techniques to enhance science teaching. In this month's issue an upper elementary Science, technology, engineering, and math (STEM) challenge brings an engineer into the classroom while emphasizing cooperation, communication, and creativity. STEM activities come in various shapes and sizes. Some are quite involved…

  9. Genetically engineered T cells to target EGFRvIII expressing glioblastoma

    PubMed Central

    Bullain, Szofia S.; Sahin, Ayguen; Szentirmai, Oszkar; Sanchez, Carlos; Lin, Ning; Baratta, Elizabeth; Waterman, Peter; Weissleder, Ralph; Mulligan, Richard C.

    2009-01-01

    Glioblastoma remains a significant therapeutic challenge, warranting further investigation of novel therapies. We describe an immunotherapeutic strategy to treat glioblastoma based on adoptive transfer of genetically modified T-lymphocytes (T cells) redirected to kill EGFRvIII expressing gliomas. We constructed a chimeric immune receptor (CIR) specific to EGFRvIII, (MR1-ζ). After in vitro selection and expansion, MR1-ζ genetically modified primary human T-cells specifically recognized EGFRvIII-positive tumor cells as demonstrated by IFN-γ secretion and efficient tumor lysis compared to control CIRs defective in EGFRvIII binding (MRB-ζ) or signaling (MR1-delζ). MR1-ζ expressing T cells also inhibited EGFRvIII-positive tumor growth in vivo in a xenografted mouse model. Successful targeting of EGFRvIII-positive tumors via adoptive transfer of genetically modified T cells may represent a new immunotherapy strategy with great potential for clinical applications. PMID:19387557

  10. Molecular tectonics: crystal engineering of mixed valence Fe(II)/Fe(III) solid solutions.

    PubMed

    Dechambenoit, Pierre; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2010-02-14

    Based on isostructurality between crystals formed upon combining the dicationic tecton 2 with either M(3)Fe(III)(CN)(6) or M(4)Fe(II)(CN)(6) (M = Cs), a rare example of an H-bonded mixed valence Fe(ii)-Fe(iii) solid solution ((Cs(2)2(3)-[Fe(II)(CN)(6)](2))(0.83)(2(3)-[Fe(III)(CN)(6)](2))(0.17))) and curious necklace-like composite crystals were generated.

  11. Flight Investigation of the Cooling Characteristics of a Two-row Radial Engine Installation III : Engine Temperature Distribution

    NASA Technical Reports Server (NTRS)

    Rennak, Robert M; Messing, Wesley E; Morgan, James E

    1946-01-01

    The temperature distribution of a two-row radial engine in a twin-engine airplane has been investigated in a series of flight tests. The test engine was operated over a wide range of conditions at density altitudes of 5000 and 20,000 feet; quantitative results are presented showing the effects of flight and engine variables upon average engine temperature and over-all temperature spread. Discussions of the effect of the variables on the shape of the temperature patterns and on the temperature distribution of individual cylinders are also included. The results indicate that, for the tests conducted, the temperature distribution patterns were chiefly determined by the fuel-air ratio and cooling-air distributions. It was possible to calculate individual cylinder temperature, on the assumption of equal power distribution among cylinders, to within an average of plus or minus 14 degrees F. of the actual temperature. A considerable change occurred in either the spread or the thrust axis, the average engine fuel-air ratio, the engine speed, the power, or the blower ratio. Smaller effects on the temperature pattern were noticed with a change in cowl-flap opening and altitude. In most of the tests, a change in conditions affected the temperature of the barrels less than that of the heads. The variation of flight and engine variables had a negligible effect on the temperature distributions of the individual cylinders. (author)

  12. Structure and dynamics of the fibronectin-III domains of Aplysia californica cell adhesion molecules.

    PubMed

    Kelly, Catherine M; Muzard, Julien; Brooks, Bernard R; Lee, Gil U; Buchete, Nicolae-Viorel

    2015-04-21

    Due to their homophilic and heterophilic binding properties, cell adhesion molecules (CAMs) such as integrin, cadherin and the immunoglobulin superfamily CAMs are of primary importance in cell-cell and cell-substrate interactions, signalling pathways and other crucial biological processes. We study the molecular structures and conformational dynamics of the two fibronectin type III (Fn-III) extracellular domains of the Aplysia californica CAM (apCAM) protein, by constructing and probing an atomically-detailed structural model based on apCAM's homology with other CAMs. The stability and dynamic properties of the Fn-III domains, individually and in tandem, are probed and analysed using all-atom explicit-solvent molecular dynamics (MD) simulations and normal mode analysis of their corresponding elastic network models. The refined structural model of the Fn-III tandem of apCAM reveals a specific pattern of amino acid interactions that controls the stability of the β-sheet rich structure and could affect apCAM's response to physical or chemical changes of its environment. It also exposes the important role of several specific charged residues in modulating the structural properties of the linker segment connecting the two Fn-III domains, as well as of the inter-domain interface.

  13. (Porphyrinato)bis(phthalocyaninato)dilanthanide(III) complexes presenting a sandwich triple-decker-like structure

    SciTech Connect

    Moussavi, M.; De Cian, A.; Fischer, J.; Weiss, R.

    1986-06-18

    Bis(phthalocyaninato)lanthanide(III) derivatives presenting a sandwich-type structure have been known for many years. These complexes are still intensively studied due to their semi-conductor and electrochromic properties. The synthesis and properties of bis(porphyrinato) and tris(porphyrinato)lanthanide(III) derivatives have also been reported. X-ray structural studies have shown that bis(porphyrinato) complexes have geometries that are similar to those displayed by the LnPc/sub 2/ complexes (Ln = lanthanide; Pc = phthalocyanine) whereas the tris(porphyrinato) derivatives present structures in which two lanthanide(III) metal cations are sandwiched between three macrocyclic rings in triple-decker-like geometry. Structural, magnetic, and spectroscopic properties of the green form of lutetium(III) bis(phthalocyanate) have shown that this complex is in a nonprotonated, one-electron-oxidized ligand form, Ln (Pc/sup 2 -/) (Pc..pi..). In such a molecule, the unpaired spin could be either located on one phthalocyanine ring or delocalized over both rings. In order to force the localization of the unpaired spin on one ring, the authors have tried to synthesize a dissymmetric mixed-ligand, porphyrin (Por) phthalocyanine (Pc), lanthanide sandwich Ln(Por)(Pc). However, under the conditions used, the authors obtained dilanthanide sandwich-triple-decker-like complexes. (Por(Ln)Pc(Ln)Pc) in which the two metal cations are sandwiched between three macrocyclic rings. They report the synthesis and spectral properties of such derivatives obtained with Ln = Nd(III), Eu(III), and Gd(III) and with meso-tetrakis(4-methoxyphenyl) porphyrin (H/sub 2/T(4-OCH/sub 3/)PP) and phthalocyanine (H/sub 2/Pc). The X-ray structure of the neodymim complex is also reported.

  14. Effects of Structural Flexibility on Aircraft-Engine Mounts

    NASA Technical Reports Server (NTRS)

    Phillips, W. H.

    1986-01-01

    Analysis extends technique for design of widely used type of vibration-isolating mounts for aircraft engines, in which rubber mounting pads located in plane behind center of gravity of enginepropeller combination. New analysis treats problem in statics. Results of simple approach useful in providing equations for design of vibrationisolating mounts. Equations applicable in usual situation in which engine-mount structure itself relatively light and placed between large mass of engine and other heavy components of airplane.

  15. Faculty Perceptions of Students: Structure of Faculty Characterizations, Part III.

    ERIC Educational Resources Information Center

    Davis, Junius A.

    The structure of characterizations of college students by faculty members, particularly observable and significant dimensions or trait patterns, were investigated. Student ratings by faculty members on 80 bi-polar traits, together with Scholastic Aptitude Test (SAT) scores and high school and college freshman average grades, were obtained.…

  16. Molecular and structural basis of ESCRT-III recruitment to membranes during archaeal cell division.

    PubMed

    Samson, Rachel Y; Obita, Takayuki; Hodgson, Ben; Shaw, Michael K; Chong, Parkson Lee-Gau; Williams, Roger L; Bell, Stephen D

    2011-01-21

    Members of the crenarchaeal kingdom, such as Sulfolobus, divide by binary fission yet lack genes for the otherwise near-ubiquitous tubulin and actin superfamilies of cytoskeletal proteins. Recent work has established that Sulfolobus homologs of the eukaryotic ESCRT-III and Vps4 components of the ESCRT machinery play an important role in Sulfolobus cell division. In eukaryotes, several pathways recruit ESCRT-III proteins to their sites of action. However, the positioning determinants for archaeal ESCRT-III are not known. Here, we identify a protein, CdvA, that is responsible for recruiting Sulfolobus ESCRT-III to membranes. Overexpression of the isolated ESCRT-III domain that interacts with CdvA results in the generation of nucleoid-free cells. Furthermore, CdvA and ESCRT-III synergize to deform archaeal membranes in vitro. The structure of the CdvA/ESCRT-III interface gives insight into the evolution of the more complex and modular eukaryotic ESCRT complex.

  17. RNA structure-dependent uncoupling of substrate recognition and cleavage by Escherichia coli ribonuclease III

    PubMed Central

    Calin-Jageman, Irina; Nicholson, Allen W.

    2003-01-01

    Members of the ribonuclease III superfamily of double-strand-specific endoribonucleases participate in diverse RNA maturation and decay pathways. Ribonuclease III of the gram-negative bacterium Escherichia coli processes rRNA and mRNA precursors, and its catalytic action can regulate gene expression by controlling mRNA translation and stability. It has been proposed that E.coli RNase III can function in a non-catalytic manner, by binding RNA without cleaving phosphodiesters. However, there has been no direct evidence for this mode of action. We describe here an RNA, derived from the T7 phage R1.1 RNase III substrate, that is resistant to cleavage in vitro by E.coli RNase III but retains comparable binding affinity. R1.1[CL3B] RNA is recognized by RNase III in the same manner as R1.1 RNA, as revealed by the similar inhibitory effects of a specific mutation in both substrates. Structure-probing assays and Mfold analysis indicate that R1.1[CL3B] RNA possesses a bulge– helix–bulge motif in place of the R1.1 asymmetric internal loop. The presence of both bulges is required for uncoupling. The bulge–helix–bulge motif acts as a ‘catalytic’ antideterminant, which is distinct from recognition antideterminants, which inhibit RNase III binding. PMID:12711683

  18. Theoretical discovery of stable structures of group III-V monolayers: The materials for semiconductor devices

    SciTech Connect

    Suzuki, Tatsuo

    2015-11-23

    Group III-V compounds are very important as the materials of semiconductor devices. Stable structures of the monolayers of group III-V binary compounds have been discovered by using first-principles calculations. The primitive unit cell of the discovered structures is a rectangle, which includes four group-III atoms and four group-V atoms. A group-III atom and its three nearest-neighbor group-V atoms are placed on the same plane; however, these connections are not the sp{sup 2} hybridization. The bond angles around the group-V atoms are less than the bond angle of sp{sup 3} hybridization. The discovered structure of GaP is an indirect transition semiconductor, while the discovered structures of GaAs, InP, and InAs are direct transition semiconductors. Therefore, the discovered structures of these compounds have the potential of the materials for semiconductor devices, for example, water splitting photocatalysts. The discovered structures may become the most stable structures of monolayers which consist of other materials.

  19. Head structure for OHC type internal combustion engine

    SciTech Connect

    Arakawa, T.; Kato, M.; Watanabe, K.

    1987-04-28

    A head structure is described for an OHC type internal combustion engine, comprising, a cam case fixed to a cylinder head for the engine, a bearing portions provided on the cam case for rotatably supporting a valve operating camshaft, a rocker shaft for rockably supporting valve rocker arms, and the rocker shaft being fixed to the bearing portions by bolts.

  20. Upgrading of Existing Structures. Phase III. Shelter Design Options.

    DTIC Science & Technology

    1981-05-01

    concrete. ,TT 3-24 0 1 L Fig. 3-19. Loading Configuration, Base Case, 8-inch Slab, Test No. 5. 3-25 440 " 4w 4W F-FF - UFA a1, a Z. 0 4. 0! 90 19 .. 0...simply supported and shored at midspan. The two tests differed in the type and method of shoring. In Test No. 6, the shore consisted of a structural... methods , and the correlation of the tests and results with work performed by others. This first series was also instrumental in providing data to assist

  1. Physics and Technology of III-V Pseudomorphic Structures

    DTIC Science & Technology

    1991-03-01

    otR1tstk 1- An 0^13 DAT E 4. -r ln- 90 -30 Sevt. 91 Physics and Technology of 111-V Pseudomorphic P613 Structures R&T#4 14s002 6. AUTHOR(S) I C.W. Tu 1...tightens its grip on the fiber optic cable. The able gain from I to 5 for the incoming signal from each of electrical RHEED signals leave the phototransistor...box via the two phototransistors. The variable gain allows match- BNC connectors, and the 15 V dc required by the pho- ing of the noise levels of the

  2. Synthesis, crystal structure and magnetic properties of a novel heterobimetallic rhenium(IV)-dysprosium(III) chain.

    PubMed

    Pejo, Carolina; Guedes, Guilherme P; Novak, Miguel A; Speziali, Nivaldo L; Chiozzone, Raúl; Julve, Miguel; Lloret, Francesc; Vaz, Maria G F; González, Ricardo

    2015-06-08

    The use of the mononuclear rhenium(IV) precursor [ReBr5 (H2 pydc)](-) (H2 pydc=3,5-pyridinedicarboxylic acid) as a metalloligand towards dysprosium(III) afforded the first heterobimetallic Re(IV) -Dy(III) complex. Crystal structures and static and dynamic magnetic properties of both rhenium-containing species are reported herein. The 5d-4f compound shows an extended 1D structure and the AC magnetic measurements reveal frequency dependence at low temperature suggesting slow relaxation of the magnetization.

  3. Elucidation of the Fe(III) Gallate Structure in Historical Iron Gall Ink.

    PubMed

    Ponce, Aldo; Brostoff, Lynn B; Gibbons, Sarah K; Zavalij, Peter; Viragh, Carol; Hooper, Joseph; Alnemrat, Sufian; Gaskell, Karen J; Eichhorn, Bryan

    2016-05-17

    Synthetic, structural, spectroscopic and aging studies conclusively show that the main colorant of historical iron gall ink (IGI) is an amorphous form of Fe(III) gallate·xH2O (x = ∼1.5-3.2). Comparisons between experimental samples and historical documents, including an 18th century hand-written manuscript by George Washington, by IR and Raman spectroscopy, XRD, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy confirm the relationship between the model and authentic samples. These studies settle controversy in the cultural heritage field, where an alternative structure for Fe(III) gallate has been commonly cited.

  4. Information and telecommunication system for monitoring of hydraulic engineering structures

    NASA Astrophysics Data System (ADS)

    Pavlycheva, Nadezhda K.; Akhmetgaleeva, Railia R.; Muslimov, Eduard R.; Murav'eva, Elena V.; Peplov, Artem A.; Sibgatulina, Dina S.

    2016-03-01

    In this article, we present the information and telecommunications system that allows to carry out real-time monitoring of the quality and quantity of hydraulic engineering structures in order to reduce the risk of emergencies caused by environmental damage.

  5. Aero/structural tailoring of engine blades (AERO/STAEBL)

    NASA Technical Reports Server (NTRS)

    Brown, K. W.

    1988-01-01

    This report describes the Aero/Structural Tailoring of Engine Blades (AERO/STAEBL) program, which is a computer code used to perform engine fan and compressor blade aero/structural numerical optimizations. These optimizations seek a blade design of minimum operating cost that satisfies realistic blade design constraints. This report documents the overall program (i.e., input, optimization procedures, approximate analyses) and also provides a detailed description of the validation test cases.

  6. Structural dynamic analysis of the Space Shuttle Main Engine

    NASA Technical Reports Server (NTRS)

    Scott, L. P.; Jamison, G. T.; Mccutcheon, W. A.; Price, J. M.

    1981-01-01

    This structural dynamic analysis supports development of the SSME by evaluating components subjected to critical dynamic loads, identifying significant parameters, and evaluating solution methods. Engine operating parameters at both rated and full power levels are considered. Detailed structural dynamic analyses of operationally critical and life limited components support the assessment of engine design modifications and environmental changes. Engine system test results are utilized to verify analytic model simulations. The SSME main chamber injector assembly is an assembly of 600 injector elements which are called LOX posts. The overall LOX post analysis procedure is shown.

  7. The role of strain in the surface structures of III-V alloyed semiconductor films

    NASA Astrophysics Data System (ADS)

    Bickel, Jessica E.

    As length scales continue to decrease, it is vital to understand the fundamental physical parameters governing surfaces and surface interactions. In semiconductors particularly, surface reconstructions are known to impact film growth, bulk atomic ordering and the development of interfacial structure, all of which can drastically impact device growth. While the parameters that determine surface reconstructions in homoepitaxially grown films are well known and understood, those that impact alloy film growth are less studied. This work examines the impact of strain on alloy surface reconstructions, using the III-V semiconductors as a model system for any covalently bonded crystal structure. The presence of surface reconstruction coexistence in both mixed cation and mixed anion systems suggests that localized strain fields on alloy surfaces stabilize elastic relaxation at boundaries, resulting in more complex surface structures than those seen on binary, unstrained films. Atomic size mismatch strain is shown to induce an ordering in alloyed surface reconstructions that is not seen in the non-alloyed constituent surfaces. Lattice mismatch strain is shown to both stabilize new reconstructions not common to the homoepitaxial system and to induce surface reconstruction coexistence on alloy surfaces. The supplied flux of material is shown to affect the kinetics of transformation between the two coexisting surface reconstructions and an incorporation model for material on the alloy surface is developed. The effects of strained surface reconstructions on subsequent film growth is explored and it is shown that identical films grown on two different surfaces have very different strain relaxation profiles, surface topographies and defect structures. The strain fields of surface reconstructions and defects are also shown to interact which may have an impact on the insertion of dislocations in these films. Combined together, this deep understanding of the role that alloy induced

  8. Structure and electrical characterization of gallium arsenide nanowires with different V/III ratio growth parameters

    SciTech Connect

    Muhammad, R.; Ahamad, R.; Ibrahim, Z.; Othaman, Z.

    2014-03-05

    Gallium arsenide (GaAs) nanowires were grown vertically on GaAs(111)B substrate by gold-assisted using metal-organic chemical vapour deposition. Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and conductivity atomic force microscopy (CAFM) analysis were carried out to investigate the effects of V/III ratio on structural properties and current-voltage changes in the wires. Results show that GaAs NWs grow preferably in the wurtzite crystal structure than zinc blende crystal structure with increasing V/III ratio. Additionally, CAFM studies have revealed that zincblende nanowires indicate ohmic characteristic compared to oscillation current occurred for wurtzite structures. The GaAs NWs with high quality structures are needed in solar cells technology for trapping energy that directly converts of sunlight into electricity with maximum capacity.

  9. A NdIII enantiomeric pair: Synthesis, crystal structures and near-infrared luminescent properties

    NASA Astrophysics Data System (ADS)

    Li, Feng-Cai; Li, Xi-Li; Hu, Ming; Zhang, Xue-Li; Chen, Conghui; Zhu, Cancan

    2016-08-01

    Based on enantiopure bis-bidentate N-donor ligands (-)/(+)-2,5-bis(4,5-pinene- 2-pyridyl)pyrazine (LR/LS), a new pair of NdIII enantiomers with the formula Nd(dbm)3LR/S·2H2O (R-1 and S-1 being the isomers containing the LR and LS ligands, respectively, and dbm = dibenzoylmethanate) have been isolated and characterized by X-ray crystallography and spectroscopic methods. Notably, unlike our previously reported homodinuclear EuIII and DyIII complexes based on the identical ligands (LR and LS), the dinuclear NdIII congener have not been obtained by controlling the ligand-to-metal ratio as expected, the reason of which was elucidated in this work. The crystal structure analyses of R-1 and S-1 reveal that they are mononuclear NdIII complexes and crystallize in chiral space group P212121 of the orthorhombic system. Circular dichroic (CD) spectra confirmed their chiroptical activities and enantiomeric nature. The photoluminescence investigations showed that they display characteristic near-infrared (NIR) emissions of the NdIII ions with notable emitting lifetime value.

  10. Parameter identification of civil engineering structures

    NASA Technical Reports Server (NTRS)

    Juang, J. N.; Sun, C. T.

    1980-01-01

    This paper concerns the development of an identification method required in determining structural parameter variations for systems subjected to an extended exposure to the environment. The concept of structural identifiability of a large scale structural system in the absence of damping is presented. Three criteria are established indicating that a large number of system parameters (the coefficient parameters of the differential equations) can be identified by a few actuators and sensors. An eight-bay-fifteen-story frame structure is used as example. A simple model is employed for analyzing the dynamic response of the frame structure.

  11. Molecular structure of yeast RNA polymerase III: demonstration of the tripartite transcriptive system in lower eukaryotes.

    PubMed Central

    Valenzuela, P; Hager, G L; Weinberg, F; Rutter, W J

    1976-01-01

    Homogeneous RNA polymerase III (RNA nucleotidyltransferase III) has been obtained from yeast. The subunit composition of the enzyme was examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme is composed of 12 putative subunits with molecular weights 160,000, 128,000, 82,000, 41,000, 40,500, 37,000, 34,000, 28,000, 24,000, 20,000, 14,500, and 11,000. The high-molecular-weight subunits and several of the smaller subunits of yeast RNA polymerase III are clearly different from those of enzymes I and II, indicating a distinct molecular structure. However, the molecular weights of some of the small subunits (41,000, 28,000, 24,000, and 14,500) appear to be identical to those of polymerases I and II. Thus, it is possible that the three classes of enzymes in yeast have some common subunits. As in other eukaryotes, yeast polymerase II is inhibited by relatively low concentrations of alpha-amanitin; however, contrary to what has been found in higher eukaryotes, yeast polymerase III is resistant (up to 2 mg/ml) to alpha-amanitin, while yeast polymerase I is sensitive to high concentrations of the drug (50% inhibition at 0.3 mg/ml). These results establish the existence of RNA polymerase III in yeast and provide a structural basis for the discrimination of the three functional polymerases in eukaryotes. Images PMID:772675

  12. Crystal structure of hydrazine iron(III) phosphate, the first transition metal phosphate containing hydrazine

    PubMed Central

    David, Renald

    2015-01-01

    The title compound, poly[(μ2-hydrazine)(μ4-phosphato)iron(III)], [Fe(PO4)(N2H4)]n, was prepared under hydro­thermal conditions. Its asymmetric unit contains one FeIII atom located on an inversion centre, one P atom located on a twofold rotation axis, and two O, one N and two H atoms located on general positions. The FeIII atom is bound to four O atoms of symmetry-related PO4 tetra­hedra and to two N atoms of two symmetry-related hydrazine ligands, resulting in a slightly distorted FeO4N2 octa­hedron. The crystal structure consists of a three-dimensional hydrazine/iron phoshate framework whereby each PO4 tetra­hedron bridges four FeIII atoms and each hydrazine ligand bridges two FeIII atoms. The H atoms of the hydrazine ligands are also involved in moderate N—H⋯O hydrogen bonding with phosphate O atoms. The crystal structure is isotypic with the sulfates [Co(SO4)(N2H4)] and [Mn(SO4)(N2H4)]. PMID:26870399

  13. Crystal structure of hydrazine iron(III) phosphate, the first transition metal phosphate containing hydrazine.

    PubMed

    David, Renald

    2015-12-01

    The title compound, poly[(μ2-hydrazine)(μ4-phosphato)iron(III)], [Fe(PO4)(N2H4)] n , was prepared under hydro-thermal conditions. Its asymmetric unit contains one Fe(III) atom located on an inversion centre, one P atom located on a twofold rotation axis, and two O, one N and two H atoms located on general positions. The Fe(III) atom is bound to four O atoms of symmetry-related PO4 tetra-hedra and to two N atoms of two symmetry-related hydrazine ligands, resulting in a slightly distorted FeO4N2 octa-hedron. The crystal structure consists of a three-dimensional hydrazine/iron phoshate framework whereby each PO4 tetra-hedron bridges four Fe(III) atoms and each hydrazine ligand bridges two Fe(III) atoms. The H atoms of the hydrazine ligands are also involved in moderate N-H⋯O hydrogen bonding with phosphate O atoms. The crystal structure is isotypic with the sulfates [Co(SO4)(N2H4)] and [Mn(SO4)(N2H4)].

  14. Amide I'-II' 2D IR spectroscopy provides enhanced protein secondary structural sensitivity.

    PubMed

    Deflores, Lauren P; Ganim, Ziad; Nicodemus, Rebecca A; Tokmakoff, Andrei

    2009-03-11

    We demonstrate how multimode 2D IR spectroscopy of the protein amide I' and II' vibrations can be used to distinguish protein secondary structure. Polarization-dependent amide I'-II' 2D IR experiments on poly-l-lysine in the beta-sheet, alpha-helix, and random coil conformations show that a combination of amide I' and II' diagonal and cross peaks can effectively distinguish between secondary structural content, where amide I' infrared spectroscopy alone cannot. The enhanced sensitivity arises from frequency and amplitude correlations between amide II' and amide I' spectra that reflect the symmetry of secondary structures. 2D IR surfaces are used to parametrize an excitonic model for the amide I'-II' manifold suitable to predict protein amide I'-II' spectra. This model reveals that the dominant vibrational interaction contributing to this sensitivity is a combination of negative amide II'-II' through-bond coupling and amide I'-II' coupling within the peptide unit. The empirically determined amide II'-II' couplings do not significantly vary with secondary structure: -8.5 cm(-1) for the beta sheet, -8.7 cm(-1) for the alpha helix, and -5 cm(-1) for the coil.

  15. Structural Probability Concepts Adapted to Electrical Engineering

    NASA Technical Reports Server (NTRS)

    Steinberg, Eric P.; Chamis, Christos C.

    1994-01-01

    Through the use of equivalent variable analogies, the authors demonstrate how an electrical subsystem can be modeled by an equivalent structural subsystem. This allows the electrical subsystem to be probabilistically analyzed by using available structural reliability computer codes such as NESSUS. With the ability to analyze the electrical subsystem probabilistically, we can evaluate the reliability of systems that include both structural and electrical subsystems. Common examples of such systems are a structural subsystem integrated with a health-monitoring subsystem, and smart structures. Since these systems have electrical subsystems that directly affect the operation of the overall system, probabilistically analyzing them could lead to improved reliability and reduced costs. The direct effect of the electrical subsystem on the structural subsystem is of secondary order and is not considered in the scope of this work.

  16. Sixty years from discovery to solution: crystal structure of bovine liver catalase form III

    SciTech Connect

    Foroughi, Leila M.; Kang, You-Na; Matzger, Adam J.

    2012-03-27

    The crystallization and structural characterization of bovine liver catalase (BLC) has been intensively studied for decades. Forms I and II of BLC have previously been fully characterized using single-crystal X-ray diffraction. Form III has previously been analyzed by electron microscopy, but owing to the thinness of this crystal form an X-ray crystal structure had not been determined. Here, the crystal structure of form III of BLC is presented in space group P212121, with unit-cell parameters a = 68.7, b = 173.7, c = 186.3 {angstrom}. The asymmetric unit is composed of the biological tetramer, which is packed in a tetrahedron motif with three other BLC tetramers. This higher resolution structure has allowed an assessment of the previously published electron-microscopy studies.

  17. Enhanced non-radiative energy transfer in hybrid III-nitride structures

    SciTech Connect

    Smith, R. M.; Athanasiou, M.; Bai, J.; Liu, B.; Wang, T.

    2015-09-21

    The effect of surface states has been investigated in hybrid organic/inorganic white light emitting structures that employ high efficiency, nearfield non-radiative energy transfer (NRET) coupling. The structures utilize blue emitting InGaN/GaN multiple quantum well (MQW) nanorod arrays to minimize the separation with a yellow emitting F8BT coating. Surface states due to the exposed III-nitride surfaces of the nanostructures are found to reduce the NRET coupling rate. The surface states are passivated by deposition of a silicon nitride layer on the III-nitride nanorod surface leading to reduced surface recombination. A low thickness surface passivation is shown to increase the NRET coupling rate by 4 times compared to an un-passivated hybrid structure. A model is proposed to explain the increased NRET rate for the passivated hybrid structures based on the reduction in surface electron depletion of the passivated InGaN/GaN MQW nanorods surfaces.

  18. Engineering structure and function using thermoresponsive biopolymers.

    PubMed

    Pastuszka, Martha K; MacKay, J Andrew

    2016-01-01

    Self-assembly enables exquisite control at the smallest scale and generates order among macromolecular-building blocks that remain too small to be manipulated individually. Environmental cues, such as heating, can trigger the organization of these materials from individual molecules to multipartixcle assemblies with a variety of compositions and functions. Synthetic as well as biological polymers have been engineered for these purposes; however, biological strategies can offer unparalleled control over the composition of these macromolecular-building blocks. Biologic polymers are macromolecules composed of monomeric units that can be precisely tailored at the genetic level; furthermore, they can often utilize endogenous biodegradation pathways, which may enhance their potential clinical applications. DNA (nucleotides), polysaccharides (carbohydrates), and proteins (amino acids) have all been engineered to self-assemble into nanostructures in response to a change in temperature. This focus article reviews the growing body of literature exploring temperature-dependent nano-assembly of these biological macromolecules, summarizes some of their physical properties, and discusses future directions.

  19. Computer applications for engineering/structural analysis

    SciTech Connect

    Zaslawsky, M.; Samaddar, S.K.

    1991-01-01

    Analysts and organizations have a tendency to lock themselves into specific codes with the obvious consequences of not addressing the real problem and thus reaching the wrong conclusion. This paper discusses the role of the analyst in selecting computer codes. The participation and support of a computation division in modifying the source program, configuration management, and pre- and post-processing of codes are among the subjects discussed. Specific examples illustrating the computer code selection process are described in the following problem areas: soil structure interaction, structural analysis of nuclear reactors, analysis of waste tanks where fluid structure interaction is important, analysis of equipment, structure-structure interaction, analysis of the operation of the superconductor supercollider which includes friction and transient temperature, and 3D analysis of the 10-meter telescope being built in Hawaii. Validation and verification of computer codes and their impact on the selection process are also discussed.

  20. Structural Requirements for the Space Propulsion Engine Systems

    NASA Technical Reports Server (NTRS)

    Aggarwal, Pravin K.

    2006-01-01

    In January 2004, the National Aeronautics and Space Administration (NASA) was given a vision for Space Exploration by President Bush, setting our sight on a bold new path to go back to the Moon, then to Mars and beyond. As NASA gets ready to meet the vision set by President Bush, failures are not an option. Reliability of the propulsion engine systems will play an important role in establishing an overall safe and reliable operation of these new space systems. A new standard, NASA-STD-5012, Strength and Life Assessment for Space Propulsion System Engines, has been developed to provide structural requirements for assessment of the propulsion systems engine. This standard is a complement to the current NASA-wide standard NASA-STD-5001, Structural Design and Test Factors of Safety for Spaceflight Hardware, which excluded the requirement for the engine systems (rotatory structures) along with pressure vessels. As developed, this document builds on the heritage of the multiple industrial standards related to strength and life assessment of the structures. For assuring a safe and reliable operation of a product and/or mission, establishing a set of structural assessment requirements is a key ingredient. Hence, a concentrated effort was made to improve the requirements where there are known lessons learned during the design, test, and operation phases of the Space Shuttle Main Engine (SSME) and other engine development programs. Requirements delineated in this standard are also applicable for the reusable and/or human missions. It shall be noted that "reliability of a system cannot be tested and inspected but can only be achieved if it is first designed into a system." Hence, these strength and life assessment requirements for the space propulsion system engines shall be used along with other good engineering practices, requirements, and policies.

  1. The joint WAIS-III and WMS-III factor structure: development and cross-validation of a six-factor model of cognitive functioning.

    PubMed

    Tulsky, David S; Price, Larry R

    2003-06-01

    During the standardization of the Wechsler Adult Intelligence Scale (3rd ed.; WAIS-III) and the Wechsler Memory Scale (3rd ed.; WMS-III) the participants in the normative study completed both scales. This "co-norming" methodology set the stage for full integration of the 2 tests and the development of an expanded structure of cognitive functioning. Until now, however, the WAIS-III and WMS-III had not been examined together in a factor analytic study. This article presents a series of confirmatory factor analyses to determine the joint WAIS-III and WMS-III factor structure. Using a structural equation modeling approach, a 6-factor model that included verbal, perceptual, processing speed, working memory, auditory memory, and visual memory constructs provided the best model fit to the data. Allowing select subtests to load simultaneously on 2 factors improved model fit and indicated that some subtests are multifaceted. The results were then replicated in a large cross-validation sample (N = 858).

  2. Density functional theory studies of actinide(III) motexafins (An-Motex2+, An = Ac, Cm, Lr). Structure, stability, and comparison with lanthanide(III) motexafins.

    PubMed

    Cao, Xiaoyan; Li, Quansong; Moritz, Anna; Xie, Zhizhong; Dolg, Michael; Chen, Xuebo; Fang, Weihai

    2006-04-17

    Newly developed relativistic energy-consistent 5f-in-core actinide pseudopotentials and corresponding (7s6p5d1f)/[5s4p3d1f] basis sets in the segmented contraction scheme, combined with density functional theory methods, have been used to study the molecular structure and chemical properties of selected actinide(III) motexafins (An-Motex2+, An = Ac, Cm, Lr). Structure and stability are discussed, and a comparison to the lanthanide(III) motexafins (Ln-Motex2+, Ln = La, Gd, Lu) is made. The actinide element is found to reside above the mean N5 motexafin plane, and the larger the cation, the greater the observed out-of-plane displacement. It is concluded that the actinium(III), curium(III), and lawrencium(III) cations are tightly bound to the macrocyclic skeleton, yielding stable structures. However, the calculated metal-ligand gas-phase binding energy for An-Motex2+ is about 1-2 eV lower than that of Ln-Motex2+, implying a lower stability of An-Motex2+ compared to Ln-Motex2+. Results including solvent effects imply that Ac-Motex2+ is the most stable complex in aqueous solution and should be the best candidate for experimentalists to get stable actinide(III) motexafin complexes.

  3. Crystal structure of the Yersinia type III secretion protein YscE

    SciTech Connect

    Phan, Jason; Austin, Brian P.; Waugh, David S.

    2010-12-06

    The plague-causing bacterium Yersinia pestis utilizes a contact-dependent (type III) secretion system (T3SS) to transport virulence factors from the bacterial cytosol directly into the interior of mammalian cells where they interfere with signal transduction pathways that mediate phagocytosis and the inflammatory response. The type III secretion apparatus is composed of 20-25 different Yersinia secretion (Ysc) proteins. We report here the structure of YscE, the smallest Ysc protein, which is a dimer in solution. The probable mode of oligomerization is discussed.

  4. Type III Radio Bursts and the Structure of the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Reiner, M. J.

    2003-12-01

    Type III solar radio bursts provide important information on the origin, acceleration, and propagation of particles associated with solar flares and coronal shocks. Since these radio emissions are generated by the plasma emission mechanism, observations of these solar radio transients also provide remote sensing of the plasma conditions in the corona and of the magnetic and plasma structure of the inner heliosphere. In this talk I will review the progress of type III research from their discovery in the late 40s to the most recent advances from low-frequency spacecraft observations, primarily from ISEE-3, Wind and Ulysses.

  5. Phylogeny, topology, structure and functions of membrane-bound class III peroxidases in vascular plants.

    PubMed

    Lüthje, Sabine; Meisrimler, Claudia-Nicole; Hopff, David; Möller, Benjamin

    2011-07-01

    Peroxidases are key player in the detoxification of reactive oxygen species during cellular metabolism and oxidative stress. Membrane-bound isoenzymes have been described for peroxidase superfamilies in plants and animals. Recent studies demonstrated a location of peroxidases of the secretory pathway (class III peroxidases) at the tonoplast and the plasma membrane. Proteomic approaches using highly enriched plasma membrane preparations suggest organisation of these peroxidases in microdomains, a developmentally regulation and an induction of isoenzymes by oxidative stress. Phylogenetic relations, topology, putative structures, and physiological function of membrane-bound class III peroxidases will be discussed.

  6. The Structure-Mapping Engine: Algorithm and Examples.

    ERIC Educational Resources Information Center

    Falkenhainer, Brian; And Others

    This description of the Structure-Mapping Engine (SME), a flexible, cognitive simulation program for studying analogical processing which is based on Gentner's Structure-Mapping theory of analogy, points out that the SME provides a "tool kit" for constructing matching algorithms consistent with this theory. This report provides: (1) a…

  7. Structural Characteristics of University Engineering Students' Conceptions of Energy.

    ERIC Educational Resources Information Center

    Liu, Xiufeng; Ebenezer, Jazlin; Fraser, Duncan M.

    2002-01-01

    Examines structural characteristics of university engineering students' conceptions of energy elicited through paragraph writing and their relations with categories of their conceptions specific to energy in solution processes identified through interviews. Reports that structures of students' conceptions are characterized primarily by…

  8. Reduction of structural Fe(III) in nontronite by methanogen Methanosarcina barkeri

    USGS Publications Warehouse

    Liu, D.; Dong, Hailiang H.; Bishop, M.E.; Wang, Hongfang; Agrawal, A.; Tritschler, S.; Eberl, D.D.; Xie, S.

    2011-01-01

    Clay minerals and methanogens are ubiquitous and co-exist in anoxic environments, yet it is unclear whether methanogens are able to reduce structural Fe(III) in clay minerals. In this study, the ability of methanogen Methanosarcina barkeri to reduce structural Fe(III) in iron-rich smectite (nontronite NAu-2) and the relationship between iron reduction and methanogenesis were investigated. Bioreduction experiments were conducted in growth medium using three types of substrate: H2/CO2, methanol, and acetate. Time course methane production and hydrogen consumption were measured by gas chromatography. M. barkeri was able to reduce structural Fe(III) in NAu-2 with H2/CO2 and methanol as substrate, but not with acetate. The extent of bioreduction, as measured by the 1,10-phenanthroline method, was 7-13% with H2/CO2 as substrate, depending on nontronite concentration (5-10g/L). The extent was higher when methanol was used as a substrate, reaching 25-33%. Methanogenesis was inhibited by Fe(III) reduction in the H2/CO2 culture, but enhanced when methanol was used. High charge smectite and biogenic silica formed as a result of bioreduction. Our results suggest that methanogens may play an important role in biogeochemical cycling of iron in clay minerals and may have important implications for the global methane budget. ?? 2010 Elsevier Ltd.

  9. Afghanistan Security Forces Fund Phase III-U.S. Army Corps of Engineers Real Property Accountability

    DTIC Science & Technology

    2009-04-14

    None A.1., B.1. Commander, U.S. Army Corps of Engineers, Afghanistan Engineer District None A.1., A.2., B.1., B.2., B.3. ii Table of Contents...requirement for an oxygen supply system at NMH. The NMH phase II contract, awarded on August 1, 2006, included option 0016 to replace the oxygen supply...Proposals (RFP). The Kabul NMH phase II contract file did not document that this planning coordination took place. AED exercised this contract

  10. Engineering intelligent structures for energy efficiency

    NASA Astrophysics Data System (ADS)

    Strojnik, M.; Garcia-Torales, G.; Scholl, M. K.; Kranjc, T.

    2016-09-01

    The current philosophy of designing intelligent buildings emphasizes the use of materials whose performance is compatible with thermal environment that changes daily and seasonally. Ideally, engineering designs should incorporate features to reflect as much energy as feasible and store excess thermal energy. This may be for usage during periods when thermal energy is needed for heating. We show that current construction design methods may be improved for energy efficiency, by incorporating an attic as an transitional space for energy storage during summer, and by employing roof materials with high reflectivity in the visible and in the near IR (up to about 1.9 μm). Thus, traditional red or pink brick roofs, potentially glazed or covered with low reflectivity coating, would likely remain (become again) the preferred construction material.

  11. Simultaneous analysis and design. [in structural engineering

    NASA Technical Reports Server (NTRS)

    Haftka, R. T.

    1985-01-01

    Optimization techniques are increasingly being used for performing nonlinear structural analysis. The development of element by element (EBE) preconditioned conjugate gradient (CG) techniques is expected to extend this trend to linear analysis. Under these circumstances the structural design problem can be viewed as a nested optimization problem. There are computational benefits to treating this nested problem as a large single optimization problem. The response variables (such as displacements) and the structural parameters are all treated as design variables in a unified formulation which performs simultaneously the design and analysis. Two examples are used for demonstration. A seventy-two bar truss is optimized subject to linear stress constraints and a wing box structure is optimized subject to nonlinear collapse constraints. Both examples show substantial computational savings with the unified approach as compared to the traditional nested approach.

  12. Situated learning methodologies and assessment in civil engineering structures education

    NASA Astrophysics Data System (ADS)

    Bertz, Michael Davis

    This thesis describes an overarching study of civil engineering undergraduate structural education through student performance in recalling and applying basic structural engineering knowledge, and the viability of alternative situated learning environments for more effectively supporting the learning of this knowledge. To properly ground this study, a thorough investigation of related work in assessment, cognitive science, educational technology, and design education was completed, with connections and applications to civil engineering education highlighted. The experimental work of the thesis is organized into three parts: an assessment of civil engineering undergraduates' fundamental structural engineering knowledge and abilities; the development and testing of a software support environment for situated learning, the Civil Engineering Learning Library (CELL); and, the implementation and evaluation of the design studio, a pedagogical model for situated learning in the classroom. The results of the assessment study indicate that civil engineering seniors (and also students earlier in the curriculum) have difficulty retaining and applying basic knowledge of structural behavior, especially doing so in a flexible fashion in design situations. The survey also suggests that visualization plays an important role in understanding structural behavior. Tests with the CELL system show that a cognitively-flexible multimedia environment can support structural learning, but were inconclusive about whether the computer-based system helped the students to learn better than conventional classroom lecture. Two trial implementations of the design studio indicate that the studio model can serve as a powerful situated learning environment, and that it can be scaled up to reasonable class sizes. Significant requirements are associated with this model, however, primarily in faculty involvement, but also in physical resources and student time. In addition to these conclusions about the

  13. MAPLE deposition of Mn(III) metalloporphyrin thin films: Structural, topographical and electrochemical investigations

    NASA Astrophysics Data System (ADS)

    Cristescu, R.; Popescu, C.; Popescu, A. C.; Grigorescu, S.; Mihailescu, I. N.; Ciucu, A. A.; Iordache, S.; Andronie, A.; Stamatin, I.; Fagadar-Cosma, E.; Chrisey, D. B.

    2011-04-01

    We report the deposition by MAPLE of metallized nanostructured (5,10,15,20-tetraphenyl)porphinato manganese(III) chloride thin films onto gold screen-printed electrodes, or <1 1 1> Si substrates. The deposited nanostructures were characterized by atomic force microscopy and exhibited globular structures with average diameters decreasing with laser fluence. Raman spectroscopy showed that no major decomposition appeared. We have investigated the Mn(III)-metalloporphyrin thin films by cyclic voltammetry in order to evaluate the potential bio/chemosensing activity on dopamine neurotransmitter analyte. We have found that the manganese(III)-porphyrin is appropriate as a single mediator for dopamine sensing in the specific case of gold screen-printed electrodes.

  14. Geometric and Electronic Structure of a Peroxomanganese(III) Complex Supported by a Scorpionate Ligand

    PubMed Central

    Colmer, Hannah E.; Geiger, Robert A.; Leto, Domenick F.; Wijeratne, Gayan B.; Day, Victor W.; Jackson, Timothy A.

    2014-01-01

    A monomeric MnII complex has been prepared with the facially-coordinating TpPh2 ligand, (TpPh2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate). The X-ray crystal structure shows three coordinating solvent molecules resulting in a six-coordinate complex with Mn-ligand bond lengths that are consistent with a high-spin MnII ion. Treatment of this MnII complex with excess KO2 at room temperature resulted in the formation of a MnIII-O2 complex that is stable for several days at ambient conditions, allowing for the determination of the X-ray crystal structure of this intermediate. The electronic structure of this peroxomanganese(III) adduct was examined by using electronic absorption, electron paramagnetic resonance (EPR), low-temperature magnetic circular dichroism (MCD), and variable-temperature variable-field (VTVH) MCD spectroscopies. Density functional theory (DFT), time-dependent (TD)-DFT, and multireference ab initio CASSCF/NEVPT2 calculations were used to assign the electronic transitions and further investigate the electronic structure of the peroxomanganese(III) species. The lowest ligand-field transition in the electronic absorption spectrum of the MnIII-O2 complex exhibits a blue shift in energy compared to other previously characterized peroxomanganese(III) complexes that results from a large axial bond elongation, reducing the metal-ligand covalency and stabilizing the σ-antibonding Mn dz2 MO that is the donor MO for this transition. PMID:25312785

  15. Inspection of the Engineering Condition of Underwater Concrete Structures

    DTIC Science & Technology

    1989-04-01

    information, bulletins, and reports of work accomplished and planned on the evaluation and repair of concrete structures. Research Needs 159. Risse! et al...43-85-01 O&M, Port Hueneme, CA. Hansen, W. C. 1965 (May). "Twenty-Year Report on the Long-Term Study of Cement Performance in Concrete ," Research ...REPAIR, EVALUATION, MAINTENANCE, AND REHABILITATION RESEARCH PROGRAM TECHNICAL REPORT REMR-CS-9 INSPECTION OF THE ENGINE~:RING CONDITION OF

  16. Purification and Subunit Structure of DNA-dependent RNA Polymerase III from Wheat Germ 1

    PubMed Central

    Jendrisak, Jerry

    1981-01-01

    A rapid and simple, large-scale method for the purification of DNA-dependent RNA polymerase III (EC 2.7.7.6) from wheat germ is presented. The method involves enzyme extraction at low ionic strength, polyethyleneimine fractionation, (NH4)2SO4 precipitation, and chromatography on DEAE-Sepharose CL-6B, DEAE-cellulose, and heparin agarose. Milligram quantities of highly purified enzyme can be obtained from kilogram quantities of starting material in 2 to 3 days. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicates that RNA polymerase III contains 14 subunits with molecular weights of: 150,000; 130,000; 94,000; 55,000; 38,000; 30,000; 28,000; 25,000; 24,500; 20,500; 20,000; 19,500; 17,800; and 17,000. Subunit structure comparison of wheat germ RNA polymerases I, II, and III indicates that all three enzymes may contain common subunits with molecular weights 20,000, 17,800, and 17,000. In addition, RNA polymerases II and III may contain a common subunit with a molecular weight of 25,000, and RNA polymerases I and III may contain a common subunit with a molecular weight of 38,000. Images PMID:16661690

  17. Production of fine structures in type III solar radio bursts due to turbulent density profiles

    SciTech Connect

    Loi, Shyeh Tjing; Cairns, Iver H.; Li, Bo

    2014-07-20

    Magnetic reconnection events in the corona release energetic electron beams along open field lines, and the beams generate radio emission at multiples of the electron plasma frequency f{sub p} to produce type III solar radio bursts. Type III bursts often exhibit irregularities in the form of flux modulations with frequency and/or local temporal advances and delays, and a type IIIb burst represents the extreme case where a type III burst is fragmented into a chain of narrowband features called striae. Remote and in situ spacecraft measurements have shown that density turbulence is ubiquitous in the corona and solar wind, and often exhibits a Kolmogorov power spectrum. In this work, we numerically investigate the effects of one-dimensional macroscopic density turbulence (along the beam direction) on the behavior of type III bursts, and find that this turbulence produces stria-like fine structures in the dynamic spectra of both f{sub p} and 2 f{sub p} radiation. Spectral and temporal fine structures in the predicted type III emission are produced by variations in the scattering path lengths and group speeds of radio emission, and in the locations and sizes of emitting volumes. Moderate turbulence levels yield flux enhancements with much broader half-power bandwidths in f{sub p} than 2 f{sub p} emission, possibly explaining the often observed type IIIb-III harmonic pairs as being where intensifications in 2 f{sub p} radiation are not resolved observationally. Larger turbulence levels producing trough-peak regions in the plasma density profile may lead to broader, resolvable intensifications in 2 f{sub p} radiation, which may account for the type IIIb-IIIb pairs that are sometimes observed.

  18. Educating next-generation civil engineers about smart structures technology

    NASA Astrophysics Data System (ADS)

    Zhang, Yunfeng

    2005-05-01

    The implementation of smart structures technology in the design, construction and maintenance of civil and mechanical systems have been shown beneficial to the performance enhancement, operating efficiency and reliability of structural systems. However, most of today's engineering students are unaware of the remarkable properties of smart sensors and many applications of smart structures technology. It is thus desirable to prepare the future engineers of the society for the cutting-edge technologies in smart structures, for which they may see broad application in their generation. Pioneering work in incorporating smart structures technologies into civil engineering curriculum has been done by the writer at Lehigh University and is described in this paper. In particular, a graduate-level course entitled "Smart Structural Systems" has been taught in the Spring Semester of Year 2004 at Lehigh University. To better convey the course material to students, a smart structures test-bed, which is used not only to showcase various technological aspects of a smart structural system but also offer students an opportunity to gain hands-on experience by doing experiments has been under development at Lehigh University. The hands-on experience that could be developed with the smart structures test-bed is believed being essential for students to have a good understanding and mastering of the smart structures technologies.

  19. Crystal structure of class III chitinase from pomegranate provides the insight into its metal storage capacity.

    PubMed

    Masuda, Taro; Zhao, Guanghua; Mikami, Bunzo

    2015-01-01

    Chitinase hydrolyzes the β-1,4-glycosidic bond in chitin. In higher plants, this enzyme has been regarded as a pathogenesis-related protein. Recently, we identified a class III chitinase, which functions as a calcium storage protein in pomegranate (Punica granatum) seed (PSC, pomegranate seed chitinase). Here, we solved a crystal structure of PSC at 1.6 Å resolution. Although its overall structure, including the structure of catalytic site and non-proline cis-peptides, was closely similar to those of other class III chitinases, PSC had some unique structural characteristics. First, there were some metal-binding sites with coordinated water molecules on the surface of PSC. Second, many unconserved aspartate residues were present in the PSC sequence which rendered the surface of PSC negatively charged. This acidic electrostatic property is in contrast to that of hevamine, well-characterized plant class III chitinase, which has rather a positively charged surface. Thus, the crystal structure provides a clue for metal association property of PSC.

  20. Polarization engineering and approaches for high-performance III-nitride light emitters

    NASA Astrophysics Data System (ADS)

    Arif, Ronald A.

    Light emitting diodes (LEDs) have been increasingly integrated into mainstream lighting. In all applications requiring single-colored light, LEDs have outperformed filtered incandescent lamps. However, there are two major challenges. First is the issue of cost. High-performance nitride-based white LEDs cost roughly two orders of magnitude more expensive than incandescent lamps. The second challenge is color rendering---quantified by Color Rendering Index (CRI). Today's nitride white light LEDs still rely on the mixing of blue light from blue InGaN LEDs and yellow phosphor, and the CRI is relatively low. The best white LEDs to date have a CRI of 70--80, in comparison to traditional lamps, which generally have a CRI close to 100, and able to represent the true color of an object. An ideal way to improve the CRI is by mixing the luminescence of primary color LEDs. However, in order to make this approach viable, all the LEDs have to be based on a single materials platform. AlInGaN is the only materials system to date with the potential to fulfill this, since the bandgap of this nitride compound (with varying amount of Al, In, and Ga) can be varied from UV to IR range. There is still a lot of room for improvement in the efficiencies of nitride blue and green LEDs, while nitride-based active region emitting in the red wavelength (lambda ˜ 650-nm) regime is not realizable yet. In this dissertation, methods to increase internal quantum efficiency by polarization field engineering have been proposed. Two novel structures based on (1) staggered InGaN QW and (2) type-II InGaN-GaNAs QW have been investigated. Staggered InGaN QWs have shown improvement in the photoluminescence, cathodoluminescence, and LED output power, which agree well with numerical model prediction. All materials and devices in this work have been designed, grown and fabricated in-house. For the LED fabrication, a method based on selective area epitaxy---which bypasses dry-etching---has been utilized. In

  1. Crystal structures of two cross-bridged chromium(III) tetra­aza­macrocycles

    PubMed Central

    Prior, Timothy J.; Maples, Danny L.; Maples, Randall D.; Hoffert, Wesley A.; Parsell, Trenton H.; Silversides, Jon D.; Archibald, Stephen J.; Hubin, Timothy J.

    2014-01-01

    The crystal structure of di­chlorido­(4,10-dimethyl-1,4,7,10-tetra­aza­bicyclo­[5.5.2]tetra­deca­ne)chromium(III) hexa­fluorido­phosphate, [CrCl2(C12H26N4)]PF6, (I), has monoclinic symmetry (space group P21/n) at 150 K. The structure of the related di­chlorido­(4,11-dimethyl-1,4,8,11-tetra­aza­bicyclo­[6.6.2]hexa­deca­ne)chromium(III) hexa­fluorido­phosphate, [CrCl2(C14H30N4)]PF6, (II), also displays monoclinic symmetry (space group P21/c) at 150 K. In each case, the CrIII ion is hexa­coordinate with two cis chloride ions and two non-adjacent N atoms bound cis equatorially and the other two non-adjacent N atoms bound trans axially in a cis-V conformation of the macrocycle. The extent of the distortion from the preferred octa­hedral coordination geometry of the CrIII ion is determined by the parent macrocycle ring size, with the larger cross-bridged cyclam ring in (II) better able to accommodate this preference and the smaller cross-bridged cyclen ring in (I) requiring more distortion away from octa­hedral geometry. PMID:25309165

  2. Structures, performance, benefit, cost study. [gas turbine engines

    NASA Technical Reports Server (NTRS)

    Feder, E.

    1981-01-01

    Aircraft engine structures were studied to identify the advanced structural technologies that would provide the most benefits to future aircraft operations. A series of studies identified engine systems with the greatest potential for improvements. Based on these studies, six advanced generic structural concepts were selected and conceptually designed. The benefits of each concept were quantitatively assessed in terms of thrust specific fuel consumption, weight, cost, maintenance cost, fuel burned and direct operating cost plus interest. The probability of success of each concept was also determined. The concepts were ranked and the three most promising were selected for further study which consisted of identifying and comprehensively outlining the advanced technologies required to develop these concepts for aircraft engine application. Analytic, fabrication, and test technology developments are required. The technology programs outlined emphasize the need to provide basic, fundamental understanding of technology to obtain the benefit goals.

  3. Calcium ions stabilize a protein structure of hemolytic lectin CEL-III from marine invertebrate Cucumaria echinata.

    PubMed

    Sallay, I; Tojo, S; Nomiyama, K; Kouzuma, Y; Kimura, M; Yamasaki, N

    2001-06-01

    CEL-III, a galactose/N-acetylgalactosamine (Gal/GalNAc)-specific lectin purified from a marine invertebrate, Cucumaria echinata, has a strong hemolytic activity, especially toward human and rabbit erythrocytes in the presence of Ca2+. We evaluated the role of Ca2+ in hemagglutinating and hemolytic activities of CEL-III. We found that Ca2+ is closely associated with both activities of CEL-III. The fluorescence spectra of CEL-III upon binding to Ca2+ were measured. The result showed a structural change of CEL-III in the presence of Ca2+. The structural change of CEL-III upon Ca2+ binding was further demonstrated by stabilization against urea denaturation and by insusceptibility to protease digestions. CEL-III was completely unfolded at a low concentration of 2 M urea, while CEL-III complexed with Ca2+ was stable in 6 M urea. As for protease digestions, CEL-III monomer and oligomer were readily digested by trypsin, chymotrypsin, and papain in the absence of Ca2+, while they were insusceptible to the three proteases in the presence of Ca2+. The papain digestion of the decalcified oligomer produced a large C-terminal peptide, suggestting that the C-terminal region of CEL-III may participate in oligomerization of CEL-III as a core domain.

  4. Electronic Band Structures of the Highly Desirable III-V Semiconductors: TB-mBJ DFT Studies

    NASA Astrophysics Data System (ADS)

    Rehman, Gul; Shafiq, M.; Saifullah; Ahmad, Rashid; Jalali-Asadabadi, S.; Maqbool, M.; Khan, Imad; Rahnamaye-Aliabad, H.; Ahmad, Iftikhar

    2016-07-01

    The correct band gaps of semiconductors are highly desirable for their effective use in optoelectronic and other photonic devices. However, the experimental and theoretical results of the exact band gaps are quite challenging and sometimes tricky. In this article, we explore the electronic band structures of the highly desirable optical materials, III-V semiconductors. The main reason of the ineffectiveness of the theoretical band gaps of these compounds is their mixed bonding character, where large proportions of electrons reside outside atomic spheres in the intestinal regions, which are challenging for proper theoretical treatment. In this article, the band gaps of the compounds are revisited and successfully reproduced by properly treating the density of electrons using the recently developed non-regular Tran and Blaha's modified Becke-Johnson (nTB-mBJ) approach. This study additionally suggests that this theoretical scheme could also be useful for the band gap engineering of the III-V semiconductors. Furthermore, the optical properties of these compounds are also calculated and compared with the experimental results.

  5. Structure Based Formal Methods for Software Engineering

    DTIC Science & Technology

    1989-07-27

    9 3.4 The Initial PegaSys Prototype ....... ...................... 9 4 Related Research 11 References 12 Accession For NI T 1... PegaSys - that uses pictures as for- mal documentation. To our knowledge, PegaSys is the first system to manipu- late nontrivial design structures in...The Initial PegaSys Prototype PegaSys is a display-oriented, interactive environment that uses intuitive graphical pictures as formal documentation to

  6. Engineering Structurally Interacting RNA (sxRNA).

    PubMed

    Doyle, Francis; Lapsia, Sameer; Spadaro, Salvatore; Wurz, Zachary E; Bhaduri-McIntosh, Sumita; Tenenbaum, Scott A

    2017-03-28

    RNA-based three-way junctions (3WJs) are naturally occurring structures found in many functional RNA molecules including rRNA, tRNA, snRNA and ribozymes. 3WJs are typically characterized as resulting from an RNA molecule folding back on itself in cis but could also form in trans when one RNA, for instance a microRNA binds to a second structured RNA, such as a mRNA. Trans-3WJs can influence the final shape of one or both of the RNA molecules and can thus provide a means for modulating the availability of regulatory motifs including potential protein or microRNA binding sites. Regulatory 3WJs generated in trans represent a newly identified regulatory category that we call structurally interacting RNA or sxRNA for convenience. Here we show that they can be rationally designed using familiar cis-3WJ examples as a guide. We demonstrate that an sxRNA "bait" sequence can be designed to interact with a specific microRNA "trigger" sequence, creating a regulatable RNA-binding protein motif that retains its functional activity. Further, we show that when placed downstream of a coding sequence, sxRNA can be used to switch "ON" translation of that sequence in the presence of the trigger microRNA and the amount of translation corresponded with the amount of microRNA present.

  7. Engineering Structurally Interacting RNA (sxRNA)

    PubMed Central

    Doyle, Francis; Lapsia, Sameer; Spadaro, Salvatore; Wurz, Zachary E.; Bhaduri-McIntosh, Sumita; Tenenbaum, Scott A.

    2017-01-01

    RNA-based three-way junctions (3WJs) are naturally occurring structures found in many functional RNA molecules including rRNA, tRNA, snRNA and ribozymes. 3WJs are typically characterized as resulting from an RNA molecule folding back on itself in cis but could also form in trans when one RNA, for instance a microRNA binds to a second structured RNA, such as a mRNA. Trans-3WJs can influence the final shape of one or both of the RNA molecules and can thus provide a means for modulating the availability of regulatory motifs including potential protein or microRNA binding sites. Regulatory 3WJs generated in trans represent a newly identified regulatory category that we call structurally interacting RNA or sxRNA for convenience. Here we show that they can be rationally designed using familiar cis-3WJ examples as a guide. We demonstrate that an sxRNA “bait” sequence can be designed to interact with a specific microRNA “trigger” sequence, creating a regulatable RNA-binding protein motif that retains its functional activity. Further, we show that when placed downstream of a coding sequence, sxRNA can be used to switch “ON” translation of that sequence in the presence of the trigger microRNA and the amount of translation corresponded with the amount of microRNA present. PMID:28350000

  8. Asymmetric ring structure of Vps4 required for ESCRT-III disassembly

    NASA Astrophysics Data System (ADS)

    Caillat, Christophe; Macheboeuf, Pauline; Wu, Yuanfei; McCarthy, Andrew A.; Boeri-Erba, Elisabetta; Effantin, Gregory; Göttlinger, Heinrich G.; Weissenhorn, Winfried; Renesto, Patricia

    2015-12-01

    The vacuolar protein sorting 4 AAA-ATPase (Vps4) recycles endosomal sorting complexes required for transport (ESCRT-III) polymers from cellular membranes. Here we present a 3.6-Å X-ray structure of ring-shaped Vps4 from Metallosphera sedula (MsVps4), seen as an asymmetric pseudohexamer. Conserved key interface residues are shown to be important for MsVps4 assembly, ATPase activity in vitro, ESCRT-III disassembly in vitro and HIV-1 budding. ADP binding leads to conformational changes within the protomer, which might propagate within the ring structure. All ATP-binding sites are accessible and the pseudohexamer binds six ATP with micromolar affinity in vitro. In contrast, ADP occupies one high-affinity and five low-affinity binding sites in vitro, consistent with conformational asymmetry induced on ATP hydrolysis. The structure represents a snapshot of an assembled Vps4 conformation and provides insight into the molecular motions the ring structure undergoes in a concerted action to couple ATP hydrolysis to ESCRT-III substrate disassembly.

  9. Asymmetric ring structure of Vps4 required for ESCRT-III disassembly

    PubMed Central

    Caillat, Christophe; Macheboeuf, Pauline; Wu, Yuanfei; McCarthy, Andrew A.; Boeri-Erba, Elisabetta; Effantin, Gregory; Göttlinger, Heinrich G.; Weissenhorn, Winfried; Renesto, Patricia

    2015-01-01

    The vacuolar protein sorting 4 AAA–ATPase (Vps4) recycles endosomal sorting complexes required for transport (ESCRT-III) polymers from cellular membranes. Here we present a 3.6-Å X-ray structure of ring-shaped Vps4 from Metallosphera sedula (MsVps4), seen as an asymmetric pseudohexamer. Conserved key interface residues are shown to be important for MsVps4 assembly, ATPase activity in vitro, ESCRT-III disassembly in vitro and HIV-1 budding. ADP binding leads to conformational changes within the protomer, which might propagate within the ring structure. All ATP-binding sites are accessible and the pseudohexamer binds six ATP with micromolar affinity in vitro. In contrast, ADP occupies one high-affinity and five low-affinity binding sites in vitro, consistent with conformational asymmetry induced on ATP hydrolysis. The structure represents a snapshot of an assembled Vps4 conformation and provides insight into the molecular motions the ring structure undergoes in a concerted action to couple ATP hydrolysis to ESCRT-III substrate disassembly. PMID:26632262

  10. On the 1s24d Fine Structures of B III and Ne VIII

    NASA Astrophysics Data System (ADS)

    Wang, Zhiwen; Z, W. Wang; Kwong, T. Chung; Zhu, Xiaowei

    1995-01-01

    The fine structure of lithium-like 1s24d states in the literature behaves irregularly as a function of Z. The fine structures of the B III and Ne VIII fall well below the isoelectronic curve. The term energies of these two systems in the data tables also give worse agreement with the theoretical prediction. In this work, we show that the reason for this unusual situation is caused by a misidentification in the original spectra. When the correct identifications are made, the fine structures of both systems fall on the isoelectronic curve and the agreement between theory and experiment is excellent.

  11. Centrifugal Modelling of Soil Structures. Part III. The Stability of River Banks and Flood Embankments.

    DTIC Science & Technology

    1978-10-01

    CENTRIFUGAL MODELLING OF SOIL STRUCTURES. PART I1. THE STARILI--ETC(U) OCT T8 C J PADFIELD. A N SCHOFIELD DA-ERO-76GO-00U C L A S IF I E n N L...ASIIIIIIIII E]lllllEEEEEEE mEEEEEEmhhEEEE EEEEEEEEmhhEEI HhIL~ 222 LEVELA!>1 ; CENTRIFUGAL MODELLING OF SOIL STRUCTURES PART III THE STABILITY OF RIVER...8217WM 1. R NUMBER GOVI ACCESSION NO). 3. R ~CI PIENT . CATALOG NUMNL H .. PERIODCO RED Centrifugal Modelling of soil StructuresPrt = Final Technical The

  12. Can Cr( iii ) substitute for Al( iii ) in the structure of boehmite?

    SciTech Connect

    Chatterjee, Sayandev; Conroy, Michele A.; Smith, Frances N.; Jung, Hee-Joon; Wang, Zheming; Peterson, Reid A.; Huq, Ashfia; Burtt, David G.; Ilton, Eugene S.; Buck, Edgar C.

    2016-01-01

    The dissolution of boehmite is a technical issue for the Al industry because of its recalcitrant nature. In fact, a similar problem exists with boehmite in nuclear waste sludge at the Hanford site in eastern Washington State, USA. Dissolution of Al phases is required to reduce the waste loadings in the final borosilicate glass waste form. Although not the most common Al-bearing species in the sludge, boehmite may become a rate limiting step in the processing of the wastes. Hanford boehmite is an order of magnitude more resistant to dissolution in hot caustic solutions than expected from surface-normalized rates. We are exploring potential intrinsic and extrinsic effects that may limit boehmite reactivity; one clue comes from microstructural analyses that indicate an association of Cr with Al in the Hanford nuclear waste. Hence, in this first paper, we investigated the potential role of chromium on the reactivity of boehmite in caustic solution. An important finding was that irrespective of the synthesis pathway, amount of Cr(III), or the resultant morphology, there was no evidence for Cr incorporation in the bulk structure, in agreement with QM calculations. In fact, electron microscopic (EM) and spectroscopic analyses showed that Cr was enriched at the (101) edges of the boehmite. However, Cr had no measurable effect on the morphology during the synthesis step. In contrast, comparison of the morphologies of the synthetic Cr-doped and pure boehmite samples after exposure to caustic solutions provided evidence that Cr inhibited the corrosion. TEM showed that Cr was not homogeneously distributed at the surface. Consequently, Cr may have partially passivated the surface by blocking discrete energetic sites on the lateral surfaces of boehmite.

  13. Correlation Between Structural, Spectroscopic, and Reactivity Properties Within a Series of Structurally Analogous Metastable Manganese(III)-Alkylperoxo Complexes

    PubMed Central

    Coggins, Michael K.; Martin-Diaconescu, Vlad; DeBeer, Serena; Kovacs, Julie A.

    2013-01-01

    Manganese–peroxos are proposed as key intermediates in a number of important biochemical and synthetic transformations. Our understanding of the structural, spectroscopic, and reactivity properties of these metastable species is limited, however, and correlations between these properties have yet to be established experimentally. Herein we report the crystallographic structures of a series of structurally related metastable Mn(III)–OOR compounds, and examine their spectroscopic and reactivity properties. The four reported Mn(III)–OOR compounds extend the number of known end-on Mn(III)–(η1-peroxos) to six. The ligand backbone is shown to alter the metal–ligand distances and modulate the electronic properties key to bonding and activation of the peroxo. The mechanism of thermal decay of these metastable species is examined via variable-temperature kinetics. Strong correlations between structural (O–O and Mn⋯Npy,quin distances), spectroscopic (E(πv*(O–O) → Mn CT band), νO–O), and kinetic (ΔH‡ and ΔS‡) parameters for these complexes provide compelling evidence for rate-limiting O–O bond cleavage. Products identified in the final reaction mixtures of Mn(III)–OOR decay are consistent with homolytic O–O bond scission. The N-heterocyclic amines and ligand backbone (Et vs Pr) are found to modulate structural and reactivity properties, and O–O bond activation is shown, both experimentally and theoretically, to track with metal ion Lewis acidity. The peroxo O–O bond is shown to gradually become more activated as the N-heterocyclic amines move closer to the metal ion causing a decrease in π-donation from the peroxo πv*(O–O) orbital. The reported work represents one of very few examples of experimentally verified relationships between structure and function. PMID:23432090

  14. Reverse engineering chemical structures from molecular descriptors : how many solutions?

    SciTech Connect

    Brown, William Michael; Martin, Shawn Bryan; Faulon, Jean-Loup Michel

    2005-06-01

    Physical, chemical and biological properties are the ultimate information of interest for chemical compounds. Molecular descriptors that map structural information to activities and properties are obvious candidates for information sharing. In this paper, we consider the feasibility of using molecular descriptors to safely exchange chemical information in such a way that the original chemical structures cannot be reverse engineered. To investigate the safety of sharing such descriptors, we compute the degeneracy (the number of structure matching a descriptor value) of several 2D descriptors, and use various methods to search for and reverse engineer structures. We examine degeneracy in the entire chemical space taking descriptors values from the alkane isomer series and the PubChem database. We further use a stochastic search to retrieve structures matching specific topological index values. Finally, we investigate the safety of exchanging of fragmental descriptors using deterministic enumeration.

  15. AUTOMOTIVE DIESEL MAINTENANCE 1. UNIT III, MAINTAINING THE FUEL SYSTEM--DETROIT DIESEL ENGINE.

    ERIC Educational Resources Information Center

    Human Engineering Inst., Cleveland, OH.

    THIS MODULE OF A 30-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE OPERATION AND MAINTENANCE OF THE DIESEL ENGINE FUEL SYSTEM. TOPICS ARE (1) PURPOSE OF THE FUEL SYSTEM, (2) TRACING THE FUEL FLOW, (3) MINOR COMPONENTS OF THE FUEL SYSTEM, (4) MAINTENANCE TIPS, (5) CONSTRUCTION AND FUNCTION OF THE FUEL INJECTORS, AND (6)…

  16. Nontronite (NAu-1) Structure Associated with Microbial Fe(III) Reduction in Various Redox Conditions

    NASA Astrophysics Data System (ADS)

    Koo, T.; Kim, S.; Kim, J.

    2011-12-01

    Shewanella oneidensis MR-1 respires the structural Fe(III) of smectite and promotes illite formation in O2-free environment (Kostka et al., 1996, Kim et al., 2004). Since S. oneidensis is a facultative iron reducing bacterium, it is crucial to understand the structural changes induced by bio-reduction of structural Fe(III) in various redox conditions. Furthermore, the changes in cation exchange capacity (CEC) of bio-reduced nontronite upon the modification of mineral structure has not been extensively studied in terms of Fe-cycling. In this present study, we reported the evolution of nontronite structure at various time points in various redox conditions and corresponding CEC upon reduction and re-oxidation. S. oneidensis MR-1 was incubated in M1 medium with Na-lactate as the electron donor and Fe in nontronite (NAu-1) as the sole electron acceptor at pH 7 in anaerobic chamber for 3 hrs, 12 hrs, 1 day, 2 days, 4 days, 7 days, 14 days, and 21 days. O2 gas bubbling was then applied to the sample at each time point for 24 hours for re-oxidation. The triplet samples at each time point for both reduction and re-oxidation experiments were prepared. The extent of Fe(III) reduction measured by 1,10-phenanthroline method (Stucki and Anderson, 1981) indicated that the structural Fe(III) was reduced up to 8.8% of total Fe(III) within 21 days. XRD data with various treatments such as air dried, glycolated and lithium-saturated showed that K-nontronite may be formed because no discrete 10-Å illite peak was observed in Li-saturated sample upon glycolation. The CEC increased from 747 meg/kg to 1145 meg/kg during Fe(III) reduction and decreased to 954 meg/kg upon re-oxidation, supporting the possible formation of K-nontronite. The direct observation by electron microscopy verified the structural changes in nontonite in various redox conditions. The long-term experiment for 6 months, is in progress in anaerobic chamber, and results will be discussed. Kim, J. W., Dong, H., Seabaugh

  17. Engineering subwavelength photonic meta structures and devices

    NASA Astrophysics Data System (ADS)

    Fang, Xuanlai

    Meta-materials are novel photonic composites with artificial "atoms" and "molecules" that offer unparallel functionalities. For example, by structuring conductive elements we can manufacture a medium of negative permittivity and/or permeability in desired frequency ranging from microwave to infrared wavelength. Recent theory predicts that such a medium would promise "superlensing", that is, breaking the diffraction limit in conventional optical imaging. The intricate structure of these novel metamaterials and devices necessitate development of viable manufacturing technologies, especially 3D micro/nano-manufacturing techniques. To address this challenge, we developed a unique micro-rapid prototyping system with lateral definition down to 0.6mum. Our study further reveals that the photon-material interaction in the 3D volume leads to a strong correlation of the lateral and vertical dimensions. This unique manufacturing technology shows great potential in future advanced photonic metamaterials and devices. Using microfabrication methods, we realized for the first time the artificial magnetism in terahertz frequency, as well as artificial plasma. Furthermore, at optical wavelengths, I will demonstrate that superlensing can also be realized with a thin silver film. The simulation and experimental study of this intriguing property will be presented, and I will discuss its perspective to subwavelength nanolithography.

  18. Neurotypic cell attachment and growth on III-nitride lateral polarity structures.

    PubMed

    Bain, L E; Kirste, R; Johnson, C A; Ghashghaei, H T; Collazo, R; Ivanisevic, A

    2016-01-01

    III-nitride materials have recently received increasing levels of attention for their potential to successfully interface with, and sense biochemical interactions in biological systems. Expanding on available sensing schemes (including transistor-based devices,) a III-N lateral polarity structure capable of introducing quasi-phase matching through a periodic polarity grating presents a novel platform for second harmonic generation. This platform constitutes a non-linear optical phenomenon with exquisite sensitivity to the chemical state of a surface or interface. To characterize the response of a biological system to the nanostructured lateral polarity structures, we cultured neurotypic PC12 cells on AlGaN with varying ratios of Al:Ga - 0, 0.4, 0.6, and 1 - and on surfaces of varying pitch to the III-polar vs. N-polar grating - 5, 10, 20 and 50 μm. While some toxicity associated with increasing Al is observed, we documented and quantified trends in cell responses to the local material polarity and nanoscale roughness. The nitrogen-polar material has a significantly higher nanoscale roughness than III-polar regions, and a 80-200 nm step height difference between the III-polar and N-polar materials in the lateral polarity configuration generates adequate changes in topography to influence cell growth, improves cell adhesion and promotes cell migration along the direction of the features. As the designed material configuration is further explored for biochemical sensing, the lateral polarity scheme may provide a route in assessing the non-specific protein adsorption to this varying nano-topography that drives the subsequent cell response.

  19. Structural Optimization Methodology for Rotating Disks of Aircraft Engines

    NASA Technical Reports Server (NTRS)

    Armand, Sasan C.

    1995-01-01

    In support of the preliminary evaluation of various engine technologies, a methodology has been developed for structurally designing the rotating disks of an aircraft engine. The structural design methodology, along with a previously derived methodology for predicting low-cycle fatigue life, was implemented in a computer program. An interface computer program was also developed that gathers the required data from a flowpath analysis program (WATE) being used at NASA Lewis. The computer program developed for this study requires minimum interaction with the user, thus allowing engineers with varying backgrounds in aeropropulsion to successfully execute it. The stress analysis portion of the methodology and the computer program were verified by employing the finite element analysis method. The 10th- stage, high-pressure-compressor disk of the Energy Efficient Engine Program (E3) engine was used to verify the stress analysis; the differences between the stresses and displacements obtained from the computer program developed for this study and from the finite element analysis were all below 3 percent for the problem solved. The computer program developed for this study was employed to structurally optimize the rotating disks of the E3 high-pressure compressor. The rotating disks designed by the computer program in this study were approximately 26 percent lighter than calculated from the E3 drawings. The methodology is presented herein.

  20. Synthesis, Structure and Antitumour Properties of a New 1,2-Propylenediaminetetraacetate-Ruthenium(III) Compound

    PubMed Central

    Vilaplana, R.; Romero, M. A.; Quirós, M.; Salas, J. M.

    1995-01-01

    A novel complex formed by ruthenium (III) and the sequestering ligand 1,2-propylenediaminetetraacetic acid (PDTA) has been synthetized and characterized. The structure of the monomeric compound, studied by X-ray diffraction , shows an almost symmetric octahedral geometry around the metal ion, with two chlorine atoms in a cis conformation. The antitumour activity against a variety of murine and human cancers is reported. PMID:18472768

  1. Synthesis, structure and physical properties of luminescent Pr(III) β-diketonate complexes

    NASA Astrophysics Data System (ADS)

    Pereira, V. M.; Costa, A. L.; Feldl, J.; Maria, T. M. R.; Seixas de Melo, J. S.; Martín-Ramos, P.; Martín-Gil, J.; Ramos Silva, M.

    2017-02-01

    Near infrared lanthanide(III)-based light conversion molecular devices (LCMDs) are emerging as a promising class of materials for organic light-emitting diodes (OLEDs) in some niche technologies. Three of these molecular materials -two highly coordinated Pr3+β-diketonate monomers and a dimer- are presented and their structure and properties are discussed. Particular emphasis is placed on the solid-to-solid transformation observed for the homodinuclear compound.

  2. Electrical transport engineering of semiconductor superlattice structures

    NASA Astrophysics Data System (ADS)

    Shokri, Aliasghar

    2014-04-01

    We investigate the influence of doping concentration on band structures of electrons and electrical transmission in a typical aperiodic semiconductor superlattice consisting of quantum well and barrier layers, theoretically. For this purpose, we assume that each unit cell of the superlattice contains alternately two types of material GaAs (as a well) and GaAlAs (as a barrier) with six sublayers of two materials. Our calculations are based on the generalized Kronig-Penny (KP) model and the transfer matrix method within the framework of the parabolic conductance band effective mass approximation in the coherent regime. This model reduces the numerical calculation time and enables us to use the transfer matrix method to investigate transport in the superlattices. We show that by varying the doping concentration and geometrical parameters, one can easily block the transmission of the electrons. The numerical results may be useful in designing of nanoenergy filter devices.

  3. Evaluation of engineering plastic for rollover protective structure (ROPS) mounting.

    PubMed

    Comer, R S; Ayers, P D; Liu, J

    2007-04-01

    Agriculture has one of the highest fatality rates of any industry in America. Tractor rollovers are a significant contributor to the high death rate. Rollover protective structures (ROPS) have helped lower these high fatality rates on full-size tractors. However, a large number of older tractors still do not use ROPS due to the difficulty of designing and creating a mounting structure. To help reduce this difficulty, engineering plastics were evaluated for use in a ROPS mounting structure on older tractors. The use of engineering plastics around axle housings could provide a uniform mounting configuration as well as lower costs for aftermarket ROPS. Various plastics were examined through shear testing, scale model testing, and compressive strength testing. Once a material was chosen based upon strength and cost, full-scale testing of the plastic's strength on axle housings was conducted. Finally, a mounting structure was tested in static ROPS tests, and field upset tests were performed in accordance with SAE Standard J2194. Initial tests revealed that the ROPS mounting structure and axle housing combination had higher torsional strength with less twisting than the axle housing alone. An engineering plastic ROPS mounting structure was easily successful in withstanding the forces applied during the static longitudinal and lateral ROPS tests. Field upset testing revealed that the mounting structure could withstand the impact loads seen during actual upsets without a failure. During both static testing and field upset testing, no permanent twisting of the mounting structure was found. Engineering plastic could therefore be a viable option for a universal ROPS mounting structure for older tractors.

  4. The factor structure of the DSM-III-R and ICD-10 concepts of alcohol dependence.

    PubMed

    Caetano, R

    1990-01-01

    This paper describes the factor structure of the concept of alcohol dependence as proposed in two psychiatric classifications, the DSM-III-R and the ICD-10. Subjects are 219 men and 162 women who were interviewed while in treatment for alcohol-related problems in nine different treatment programs in Contra Costa county, California. Tests of hypotheses supporting a single factor and a dual factor structure of dependence were rejected by confirmatory factor analysis. Results from exploratory factor analysis show a four factor structure for the concept of dependence in DSM-III-R. For ICD-10 there is a four factor solution among men and a three factor solution among women. The item composition of these factors vary by gender and across the two classifications. However, there is good agreement between dependence as measured by DSM-III-R and ICD-10 criteria. Since work on DSM-IV is now under way, the present research aims to provide some empirical base for how future changes should be made.

  5. Lutetium(iii) aqua ion: On the dynamical structure of the heaviest lanthanoid hydration complex.

    PubMed

    Sessa, Francesco; Spezia, Riccardo; D'Angelo, Paola

    2016-05-28

    The structure and dynamics of the lutetium(iii) ion in aqueous solution have been investigated by means of a polarizable force field molecular dynamics (MD). An 8-fold square antiprism (SAP) geometry has been found to be the dominant configuration of the lutetium(iii) aqua ion. Nevertheless, a low percentage of 9-fold complexes arranged in a tricapped trigonal prism (TTP) geometry has been also detected. Dynamic properties have been explored by carrying out six independent MD simulations for each of four different temperatures: 277 K, 298 K, 423 K, 632 K. The mean residence time of water molecules in the first hydration shell at room temperature has been found to increase as compared to the central elements of the lanthanoid series in agreement with previous experimental findings. Water exchange kinetic rate constants at each temperature and activation parameters of the process have been determined from the MD simulations. The obtained structural and dynamical results suggest that the water exchange process for the lutetium(iii) aqua ion proceeds with an associative mechanism, in which the SAP hydration complex undergoes temporary structural changes passing through a 9-fold TTP intermediate. Such results are consistent with the water exchange mechanism proposed for heavy lanthanoid atoms.

  6. Structure and function of the ESCRT-II-III interface in multivesicular body biogenesis

    SciTech Connect

    Im, Young Jun; Wollert, Thomas; Boura, Evzen; Hurley, James H.

    2009-09-08

    The ESCRT-II-ESCRT-III interaction coordinates the sorting of ubiquitinated cargo with the budding and scission of intralumenal vesicles into multivesicular bodies. The interacting regions of these complexes were mapped to the second winged helix domain of human ESCRT-II subunit VPS25 and the first helix of ESCRT-III subunit VPS20. The crystal structure of this complex was determined at 2.0 {angstrom} resolution. Residues involved in structural interactions explain the specificity of ESCRT-II for Vps20, and are critical for cargo sorting in vivo. ESCRT-II directly activates ESCRT-III-driven vesicle budding and scission in vitro via these structural interactions. VPS20 and ESCRT-II bind membranes with nanomolar affinity, explaining why binding to ESCRT-II is dispensable for the recruitment of Vps20 to membranes. Docking of the ESCRT-II-VPS202 supercomplex reveals a convex membrane-binding surface, suggesting a hypothesis for negative membrane curvature induction in the nascent intralumenal vesicle.

  7. Lutetium(iii) aqua ion: On the dynamical structure of the heaviest lanthanoid hydration complex

    NASA Astrophysics Data System (ADS)

    Sessa, Francesco; Spezia, Riccardo; D'Angelo, Paola

    2016-05-01

    The structure and dynamics of the lutetium(iii) ion in aqueous solution have been investigated by means of a polarizable force field molecular dynamics (MD). An 8-fold square antiprism (SAP) geometry has been found to be the dominant configuration of the lutetium(iii) aqua ion. Nevertheless, a low percentage of 9-fold complexes arranged in a tricapped trigonal prism (TTP) geometry has been also detected. Dynamic properties have been explored by carrying out six independent MD simulations for each of four different temperatures: 277 K, 298 K, 423 K, 632 K. The mean residence time of water molecules in the first hydration shell at room temperature has been found to increase as compared to the central elements of the lanthanoid series in agreement with previous experimental findings. Water exchange kinetic rate constants at each temperature and activation parameters of the process have been determined from the MD simulations. The obtained structural and dynamical results suggest that the water exchange process for the lutetium(iii) aqua ion proceeds with an associative mechanism, in which the SAP hydration complex undergoes temporary structural changes passing through a 9-fold TTP intermediate. Such results are consistent with the water exchange mechanism proposed for heavy lanthanoid atoms.

  8. Structure and function of the ESCRT II-III interface in multivesicular body biogenesis

    PubMed Central

    Im, Young Jun; Wollert, Thomas; Boura, Evzen; Hurley, James H.

    2009-01-01

    SUMMARY The ESCRT-II-ESCRT-III interaction coordinates the sorting of ubiquitinated cargo with the budding and scission of intralumenal vesicles into multivesicular bodies. The interacting regions of these complexes were mapped to the second winged-helix domain of human ESCRT-II subunit VPS25 and the first helix of ESCRT-III subunit VPS20. The crystal structure of this complex was determined at 2.0 Å resolution. Residues involved in structural interactions explain the specificity of ESCRT-II for Vps20, and are critical for cargo sorting in vivo. ESCRT-II directly activates ESCRT-III driven vesicle budding and scission in vitro via these structural interactions. VPS20 and ESCRT-II bind membranes with nanomolar affinity, explaining why binding to ESCRT-II is dispensable for the recruitment of Vps20 to membranes. Docking of the ESCRT-II -VPS202 supercomplex reveals a convex membrane-binding surface, suggesting a hypothesis for negative membrane curvature induction in the nascent intralumenal vesicle. PMID:19686684

  9. Structural basis for activation, assembly and membrane binding of ESCRT-III Snf7 filaments.

    PubMed

    Tang, Shaogeng; Henne, W Mike; Borbat, Peter P; Buchkovich, Nicholas J; Freed, Jack H; Mao, Yuxin; Fromme, J Christopher; Emr, Scott D

    2015-12-15

    The endosomal sorting complexes required for transport (ESCRTs) constitute hetero-oligomeric machines that catalyze multiple topologically similar membrane-remodeling processes. Although ESCRT-III subunits polymerize into spirals, how individual ESCRT-III subunits are activated and assembled together into a membrane-deforming filament remains unknown. Here, we determine X-ray crystal structures of the most abundant ESCRT-III subunit Snf7 in its active conformation. Using pulsed dipolar electron spin resonance spectroscopy (PDS), we show that Snf7 activation requires a prominent conformational rearrangement to expose protein-membrane and protein-protein interfaces. This promotes the assembly of Snf7 arrays with ~30 Å periodicity into a membrane-sculpting filament. Using a combination of biochemical and genetic approaches, both in vitro and in vivo, we demonstrate that mutations on these protein interfaces halt Snf7 assembly and block ESCRT function. The architecture of the activated and membrane-bound Snf7 polymer provides crucial insights into the spatially unique ESCRT-III-mediated membrane remodeling.

  10. Structural basis for activation, assembly and membrane binding of ESCRT-III Snf7 filaments

    PubMed Central

    Tang, Shaogeng; Henne, W Mike; Borbat, Peter P; Buchkovich, Nicholas J; Freed, Jack H; Mao, Yuxin; Fromme, J Christopher; Emr, Scott D

    2015-01-01

    The endosomal sorting complexes required for transport (ESCRTs) constitute hetero-oligomeric machines that catalyze multiple topologically similar membrane-remodeling processes. Although ESCRT-III subunits polymerize into spirals, how individual ESCRT-III subunits are activated and assembled together into a membrane-deforming filament remains unknown. Here, we determine X-ray crystal structures of the most abundant ESCRT-III subunit Snf7 in its active conformation. Using pulsed dipolar electron spin resonance spectroscopy (PDS), we show that Snf7 activation requires a prominent conformational rearrangement to expose protein-membrane and protein-protein interfaces. This promotes the assembly of Snf7 arrays with ~30 Å periodicity into a membrane-sculpting filament. Using a combination of biochemical and genetic approaches, both in vitro and in vivo, we demonstrate that mutations on these protein interfaces halt Snf7 assembly and block ESCRT function. The architecture of the activated and membrane-bound Snf7 polymer provides crucial insights into the spatially unique ESCRT-III-mediated membrane remodeling. DOI: http://dx.doi.org/10.7554/eLife.12548.001 PMID:26670543

  11. Structure, Evolution, and Functions of Bacterial Type III Toxin-Antitoxin Systems

    PubMed Central

    Goeders, Nathalie; Chai, Ray; Chen, Bihe; Day, Andrew; Salmond, George P. C.

    2016-01-01

    Toxin-antitoxin (TA) systems are small genetic modules that encode a toxin (that targets an essential cellular process) and an antitoxin that neutralises or suppresses the deleterious effect of the toxin. Based on the molecular nature of the toxin and antitoxin components, TA systems are categorised into different types. Type III TA systems, the focus of this review, are composed of a toxic endoribonuclease neutralised by a non-coding RNA antitoxin in a pseudoknotted configuration. Bioinformatic analysis shows that the Type III systems can be classified into subtypes. These TA systems were originally discovered through a phage resistance phenotype arising due to a process akin to an altruistic suicide; the phenomenon of abortive infection. Some Type III TA systems are bifunctional and can stabilise plasmids during vegetative growth and sporulation. Features particular to Type III systems are explored here, emphasising some of the characteristics of the RNA antitoxin and how these may affect the co-evolutionary relationship between toxins and cognate antitoxins in their quaternary structures. Finally, an updated analysis of the distribution and diversity of these systems are presented and discussed. PMID:27690100

  12. Smoke Emission Tests on Series II and Series III Allison T56 Turboprop Engines

    DTIC Science & Technology

    1986-12-01

    shows schematically the ARL smoke measuring equipment. Engine exhaust _». Refrigerated water trap Stainless steel sample probe Heated sample line...a system based on ARP 1179A. Experience at ARL has confirmed one major criticism of condensed water effecting the filter paper. This was largely...overcome by ensuring that the stainless steel lines and filter luolder were maintained at a temperature of 70oC. The addition of a refrigerated water

  13. Ab initio studies on the structure of and atomic interactions in cellulose III(I) crystals.

    PubMed

    Ishikawa, Tetsuya; Hayakawa, Daichi; Miyamoto, Hitomi; Ozawa, Motoyasu; Ozawa, Tomonaga; Ueda, Kazuyoshi

    2015-11-19

    The crystal structure of cellulose III(I)was analyzed using first-principles density functional theory (DFT). The geometry was optimized using variable-cell relaxation, as implemented in Quantum ESPRESSO. The Perdew-Burke-Ernzerhof (PBE) functional with a correction term for long-range van der Waals interactions (PBE-D) reproduced the experimental structure well. By using the optimized crystal structure, the interactions existed among the cellulose chains in the crystal were precisely investigated using the NBO analysis. The results showed that the weak bonding nature of CH/O and the hydrogen bonding occur among glucose molecules in the optimized crystal structure. To investigate the strength of interaction, dimeric and trimeric glucose units were extracted from the crystal, and analyzed using MP2 ab initio counterpoise methods with BSSE correction. The results estimated the strength of the interactions. That is, the packed chains along with a-axis interacts with weak bonding nature of CH/O and dispersion interactions by -7.50 kcal/mol, and two hydrogen bonds of O2HO2…O6 and O6HO6…O2 connect the neighboring packed chains with -11.9 kcal/mol. Moreover, FMO4 calculation was also applied to the optimized crystal structure to estimate the strength of the interactions. These methods can well estimate the interactions existed in the crystal structure of cellulose III(I).

  14. A New Degree Programme in Structural Engineering and Architecture.

    ERIC Educational Resources Information Center

    Davison, J. B.; Popovic, O.; Tyas, A.

    Structural engineers and architects are educated completely independently. Although both play a major part in designing and building a nation's infrastructure, they are not encouraged to fully understand the work of each other which can result in a lack of collaboration and co-operation, often to the detriment of a project. This divide between the…

  15. Abstraction and Concreteness in the Everyday Mathematics of Structural Engineers.

    ERIC Educational Resources Information Center

    Gainsburg, Julie

    The everyday mathematics processes of structural engineers were studied and analyzed in terms of abstraction. A main purpose of the study was to explore the degree to which the notion of a gap between school and everyday mathematics holds when the scope of practices considered "everyday" is extended. J. Lave (1988) promoted a methodology…

  16. CAL Packages for Civil Engineering Hydraulics and Structural Design.

    ERIC Educational Resources Information Center

    Moss, W. D.; And Others

    1979-01-01

    Describes computer assisted learning (CAL) packages written in FORTRAN IV and developed for use in a degree course in civil engineering dealing with hydraulics and structures. All are used in the interactive mode through a terminal with a keyboard and visual display unit. (Author/CMV)

  17. Optical Engineering for Children--A Structured Approach

    ERIC Educational Resources Information Center

    McCarthy, John; Moore, R. A.

    2006-01-01

    The present paper focuses on the application of a structured template, maximum impact flow (MIF), in order to encourage young students in the area of optics and optical engineering. MIF introduces a template in terms of individual steps and linked functionality and is shown to fuse separate learning tools together into a cohesive unit.…

  18. Complex quantum networks as structured environments: engineering and probing

    NASA Astrophysics Data System (ADS)

    Nokkala, Johannes; Galve, Fernando; Zambrini, Roberta; Maniscalco, Sabrina; Piilo, Jyrki

    2016-05-01

    We consider structured environments modeled by bosonic quantum networks and investigate the probing of their spectral density, structure, and topology. We demonstrate how to engineer a desired spectral density by changing the network structure. Our results show that the spectral density can be very accurately detected via a locally immersed quantum probe for virtually any network configuration. Moreover, we show how the entire network structure can be reconstructed by using a single quantum probe. We illustrate our findings presenting examples of spectral densities and topology probing for networks of genuine complexity.

  19. Complex quantum networks as structured environments: engineering and probing

    PubMed Central

    Nokkala, Johannes; Galve, Fernando; Zambrini, Roberta; Maniscalco, Sabrina; Piilo, Jyrki

    2016-01-01

    We consider structured environments modeled by bosonic quantum networks and investigate the probing of their spectral density, structure, and topology. We demonstrate how to engineer a desired spectral density by changing the network structure. Our results show that the spectral density can be very accurately detected via a locally immersed quantum probe for virtually any network configuration. Moreover, we show how the entire network structure can be reconstructed by using a single quantum probe. We illustrate our findings presenting examples of spectral densities and topology probing for networks of genuine complexity. PMID:27230125

  20. The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export.

    PubMed

    Minamino, Tohru; Morimoto, Yusuke V; Hara, Noritaka; Aldridge, Phillip D; Namba, Keiichi

    2016-03-01

    The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+-protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration.

  1. The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export

    PubMed Central

    Minamino, Tohru; Morimoto, Yusuke V.; Hara, Noritaka; Aldridge, Phillip D.; Namba, Keiichi

    2016-01-01

    The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+–protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration. PMID:26943926

  2. Hydrogen effects in dilute III-N-V alloys: From defect engineering to nanostructuring

    SciTech Connect

    Pettinari, G.; Felici, M.; Capizzi, M.; Polimeni, A.; Trotta, R.

    2014-01-07

    The variation of the band gap energy of III-N-V semiconductors induced by hydrogen incorporation is the most striking effect that H produces in these materials. A special emphasis is given here to the combination of N-activity passivation by hydrogen with H diffusion kinetics in dilute nitrides. Secondary ion mass spectrometry shows an extremely steep (smaller than 5 nm/decade) forefront of the H diffusion profile in Ga(AsN) under appropriate hydrogenation conditions. This discovery prompts the opportunity for an in-plane nanostructuring of hydrogen incorporation and, hence, for a modulation of the material band gap energy at the nanoscale. The properties of quantum dots fabricated by a lithographically defined hydrogenation are presented, showing the zero-dimensional character of these novel nanostructures. Applicative prospects of this nanofabrication method are finally outlined.

  3. Synthesis, structure, luminescent, and magnetic properties of carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2] (Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato).

    PubMed

    Ehama, Kiyomi; Ohmichi, Yusuke; Sakamoto, Soichiro; Fujinami, Takeshi; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Tsuchimoto, Masanobu; Re, Nazzareno

    2013-11-04

    Carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [Zn(II)L(n)(H2O)2]·xH2O, Ln(III)(NO3)3·6H2O, and triethylamine, where Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each Zn(II)2Ln(III)2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO3(2-) ions. The Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of L(n) and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L(n), two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(II)2Ln(III)2 complexes are analyzed on the basis of the dicarbonato-bridged binuclear Ln(III)-Ln(III) structure, as the Zn(II) ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L(1)) and ZnGd2 (L(2)) show a ferromagnetic Gd(III)-Gd(III) interaction with J(Gd-Gd) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)ŜGd1·ŜGd2. The magnetic data of the Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of Zn(II)2Tb(III)2 complexes were observed, while those

  4. Structural-Engineering Rationales of Gold Nanoparticles for Cancer Theranostics.

    PubMed

    Chen, Wenwen; Zhang, Shaohua; Yu, Yangyang; Zhang, Huisheng; He, Qianjun

    2016-10-01

    Personalized theranostics of cancer is increasingly desired, and can be realized by virtue of multifunctional nanomaterials with possible high performances. Gold nanoparticles (GNPs) are a type of especially promising candidate for cancer theranostics, because their synthesis and modification are facile, their structures and physicochemical properties are flexibly controlled, and they are also biocompatible. Especially, the localized surface plasmon resonance and multivalent coordination effects on the surface endow them with NIR light-triggered photothermal imaging and therapy, controlled drug release, and targeted drug delivery. Although the structure, properties, and theranostic application of GNPs are considerably plentiful, no expert review systematically explains the relationships among their structure, property. and application and induces the engineering rationales of GNPs for cancer theranostics. Hence, there are no clear rules to guide the facile construction of optimal GNP structures aiming at a specific theranostic application. A series of structural-engineering rationales of GNPs for cancer theranostics is proposed through digging out the deep relationships between the structure and properties of GNPs. These rationales will be inspiring for guiding the engineering of specific and advanced GNPs for personalized cancer theranostics.

  5. Structural characterization, tissue distribution, and functional expression of murine aminoacylase III.

    PubMed

    Pushkin, Alexander; Carpenito, Gerardo; Abuladze, Natalia; Newman, Debra; Tsuprun, Vladimir; Ryazantsev, Sergey; Motemoturu, Srilakshmi; Sassani, Pakan; Solovieva, Nadezhda; Dukkipati, Ramnath; Kurtz, Ira

    2004-04-01

    Many xenobiotics are detoxified through the mercapturate metabolic pathway. The final product of the pathway, mercapturic acids (N-acetylcysteine S-conjugates), are secreted predominantly by renal proximal tubules. Mercapturic acids may undergo a transformation mediated by aminoacylases and cysteine S-conjugate beta-lyases that leads to nephrotoxic reactive thiol formation. The deacetylation of cysteine S-conjugates of N-acyl aromatic amino acids is thought to be mediated by an aminoacylase whose molecular identity has not been determined. In the present study, we cloned aminoacylase III, which likely mediates this process in vivo, and characterized its function and structure. The enzyme consists of 318 amino acids and has a molecular mass (determined by SDS-PAGE) of approximately 35 kDa. Under nondenaturing conditions, the molecular mass of the enzyme is approximately 140 kDa as determined by size-exclusion chromatography, which suggests that it is a tetramer. In agreement with this hypothesis, transmission electron microscopy and image analysis of aminoacylase III showed that the monomers of the enzyme are arranged with a fourfold rotational symmetry. Northern analysis demonstrated an approximately 1.4-kb transcript that was expressed predominantly in kidney and showed less expression in liver, heart, small intestine, brain, lung, testis, and stomach. In kidney, aminoacylase III was immunolocalized predominantly to the apical domain of S1 proximal tubules and the cytoplasm of S2 and S3 proximal tubules. The data suggest that in kidney proximal tubules, aminoacylase III plays an important role in deacetylating mercapturic acids. The predominant cytoplasmic localization of aminoacylase III may explain the greater sensitivity of the proximal straight tubule to the nephrotoxicity of mercapturic acids.

  6. Ice Protection of Turbojet Engines by Inertia Separation of Water III : Annular Submerged Inlets

    NASA Technical Reports Server (NTRS)

    Von Glahn, Uwe

    1948-01-01

    Aerodynamic and icing studies were conducted on a one-half-scale model of an annular submerged inlet for use with axial-flow turbojet engines. Pressure recoveries, screen radial-velocity profiles, circumferential mass-flow variations, and icing characteristics were determined at the compressor inlet. In order to be effective in maintaining water-free induction air, the inlet gap must be extremely small and ram-pressure recoveries consequently are low, the highest achieved being 65 percent at inlet-velocity ratio of 0.86. All inlets exhibited considerable screen icing. Severe mass-flow shifts occurred at angles of attack.

  7. Electronic structure engineering of various structural phases of phosphorene.

    PubMed

    Kaur, Sumandeep; Kumar, Ashok; Srivastava, Sunita; Tankeshwar, K

    2016-07-21

    We report the tailoring of the electronic structures of various structural phases of phosphorene (α-P, β-P, γ-P and δ-P) based homo- and hetero-bilayers through in-plane mechanical strains, vertical pressure and transverse electric field by employing density functional theory. In-plane biaxial strains have considerably modified the electronic bandgap of both homo- and hetero-bilayers while vertical pressure induces metallization in the considered structures. The γ-P homo-bilayer structure showed the highest ultimate tensile strength (UTS ∼ 6.21 GPa) upon in-plane stretching. Upon application of a transverse electric field, the variation in the bandgap of hetero-bilayers was found to be strongly dependent on the polarity of the applied field which is attributed to the counterbalance between the external electric field and the internal field induced by different structural phases and heterogeneity in the arrangements of atoms of each surface of the hetero-bilayer system. Our results demonstrate that the electronic structures of the considered hetero- and homo-bilayers of phosphorene could be modified by biaxial strain, pressure and electric field to achieve the desired properties for future nano-electronic devices.

  8. Structural Role of the Vps4-Vta1 Interface in ESCRT-III Recycling

    SciTech Connect

    Yang, Dong; Hurley, James H.

    2010-09-27

    The ESCRT complexes are required for multivesicular body biogenesis, macroautophagy, cytokinesis, and the budding of HIV-1. The final step in the ESCRT cycle is the disassembly of the ESCRT-III lattice by the AAA+ ATPase Vps4. Vps4 assembles on its membrane-bound ESCRT-III substrate with its cofactor, Vta1. The crystal structure of the dimeric VSL domain of yeast Vta1 with the small ATPase and the {beta}domains of Vps4 was determined. Residues involved in structural interactions are conserved and are required for binding in vitro and for Cps1 sorting in vivo. Modeling of the Vta1 complex in complex with the lower hexameric ring of Vps4 indicates that the two-fold axis of the Vta1 VSL domain is parallel to within {approx}20 degrees of the six-fold axis of the hexamer. This suggests that Vta1 might not crosslink the two hexameric rings of Vps4, but rather stabilizes an array of Vps4-Vta1 complexes for ESCRT-III disassembly.

  9. Structural basis for midbody targeting of spastin by the ESCRT-III protein CHMP1B

    SciTech Connect

    Yang, Dong; Rimanchi, Neggy; Renvoise, Benoit; Lippincott-Schwartz, Jennifer; Blackstone, Craig; Hurley, James H.

    2009-01-15

    The endosomal sorting complex required for transport (ESCRT) machinery, including ESCRT-III, localizes to the midbody and participates in the membrane-abscission step of cytokinesis. The ESCRT-III protein charged multivesicular body protein 1B (CHMP1B) is required for recruitment of the MIT domain-containing protein spastin, a microtubule-severing enzyme, to the midbody. The 2.5-{angstrom} structure of the C-terminal tail of CHMP1B with the MIT domain of spastin reveals a specific, high-affinity complex involving a noncanonical binding site between the first and third helices of the MIT domain. The structural interface is twice as large as that of the MIT domain of the VPS4-CHMP complex, consistent with the high affinity of the interaction. A series of unique hydrogen-bonding interactions and close packing of small side chains discriminate against the other ten human ESCRT-III subunits. Point mutants in the CHMP1B binding site of spastin block recruitment of spastin to the midbody and impair cytokinesis.

  10. Applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures

    NASA Astrophysics Data System (ADS)

    Zou, Tao; Kaminski, Miroslaw Lech

    2016-09-01

    In design and operation of floating offshore structures, one has to avoid fatigue failures caused by action of ocean waves. The aim of this paper is to investigate the applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures. The applicability was investigated for Bluewaters' FPSO (Floating Production, Storage and Offloading) which had been turret moored at Sable field for half a decade. The waves were predicted as sea-state time series consisting of one wind sea and one swell. The predicted waves were compared with wave data obtained from ERA-interim and buoy measurements. Furthermore, the fatigue calculations were also carried out for main deck and side shell locations. It has been concluded that predicted fatigue damages of main deck using WaveWatch-III are in a very good agreement regardless of differences in predicted wind waves and swells caused by differences in wave system partitioning. When compared to buoy measurements, the model underestimates fatigue damages of side shell by approximately 30 %. The reason for that has been found in wider directional spreading of actual waves. The WaveWatch-III wave model has been found suitable for the fatigue assessment. However, more attention should be paid on relative wave directionality, wave system partitioning and uncertainty analysis in further development.

  11. Investigating the Structure of the WJ-III Cognitive in Early School Age through Two Exploratory Bifactor Analysis Procedures

    ERIC Educational Resources Information Center

    Dombrowski, Stefan C.

    2014-01-01

    Two exploratory bifactor methods (e.g., Schmid-Leiman [SL] and exploratory bifactor analysis [EBFA]) were used to investigate the structure of the Woodcock-Johnson III (WJ-III) Cognitive in early school age (age 6-8). The SL procedure is recognized by factor analysts as a preferred method for EBFA. Jennrich and Bentler recently developed an…

  12. Structural tailoring of engine blades (STAEBL) theoretical manual

    NASA Technical Reports Server (NTRS)

    Brown, K. W.

    1985-01-01

    This Theoretical Manual includes the theories included in the Structural Tailoring of Engine Blades (STAEBL) computer program which was developed to perform engine fan and compressor blade numerical optimizations. These blade optimizations seek a minimum weight or cost design that satisfies practical blade design constraints, by controlling one to twenty design variables. The STAEBL constraint analyses include blade stresses, vibratory response, flutter, and foreign object damage. Blade design variables include airfoil thickness at several locations, blade chord, and construction variables: hole size for hollow blades, and composite material layup for composite blades.

  13. Structural tailoring of engine blades (STAEBL) user's manual

    NASA Technical Reports Server (NTRS)

    Brown, K. W.

    1985-01-01

    This User's Manual contains instructions and demonstration case to prepare input data, run, and modify the Structural Tailoring of Engine Blades (STAEBL) computer code. STAEBL was developed to perform engine fan and compressor blade numerical optimizations. This blade optimization seeks a minimum weight or cost design that satisfies realistic blade design constraints, by tuning one to twenty design variables. The STAEBL constraint analyses include blade stresses, vibratory response, flutter, and foreign object damage. Blade design variables include airfoil thickness at several locations, blade chord, and construction variables: hole size for hollow blades, and composite material layup for composite blades.

  14. Interdisciplinary and multilevel optimum design. [in aerospace structural engineering

    NASA Technical Reports Server (NTRS)

    Sobieszczanski-Sobieski, Jaroslaw; Haftka, Raphael T.

    1987-01-01

    Interactions among engineering disciplines and subsystems in engineering system design are surveyed and specific instances of such interactions are described. Examination of the interactions that a traditional design process in which the numerical values of major design variables are decided consecutively is likely to lead to a suboptimal design. Supporting numerical examples are a glider and a space antenna. Under an alternative approach introduced, the design and its sensitivity data from the subsystems and disciplines are generated concurrently and then made available to the system designer enabling him to modify the system design so as to improve its performance. Examples of a framework structure and an airliner wing illustrate that approach.

  15. The Structured Clinical Interview for DSM-III-R (SCID). I: History, rationale, and description.

    PubMed

    Spitzer, R L; Williams, J B; Gibbon, M; First, M B

    1992-08-01

    The history, rationale, and development of the Structured Clinical Interview for DSM-III-R (SCID) is described. The SCID is a semistructured interview for making the major Axis I DSM-III-R diagnoses. It is administered by a clinician and includes an introductory overview followed by nine modules, seven of which represent the major axis I diagnostic classes. Because of its modular construction, it can be adapted for use in studies in which particular diagnoses are not of interest. Using a decision tree approach, the SCID guides the clinician in testing diagnostic hypotheses as the interview is conducted. The output of the SCID is a record of the presence or absence of each of the disorders being considered, for current episode (past month) and for lifetime occurrence.

  16. Performance of J33 turbojet engine with shaft-power extraction III : turbine performance

    NASA Technical Reports Server (NTRS)

    Huppert, M C; Nettles, J C

    1949-01-01

    The performance of the turbine component of a J33 turbojet engine was determined over a range of turbine speeds from 8000 to 11,500 rpm.Turbine-inlet temperature was varied from the minimum required to drive the compressor to a maximum of approximately 2000 degrees R at each of several intermediate turbine speeds. Data are presented that show the horsepower developed by the turbine per pound of gas flow. The relation between turbine-inlet stagnation pressure, turbine-outlet stagnation pressure, and turbine-outlet static pressure was established. The turbine-weight-flow parameter varied from 39.2 to 43.6. The maximum turbine efficiency measured was 0.86 at a pressure ratio of 3.5 and a ratio of blade speed to theoretical nozzle velocity of 0.39. A generalized performance map of the turbine-horsepower parameter plotted against the turbine-speed parameter indicated that the best turbine efficiency is obtained when the turbine power is 10 percent greater than the compressor horsepower. The variation of efficiency with the ratio of blade speed to nozzle velocity indicated that the turbine operates at a speed above that for maximum efficiency when the engine is operated normally with the 19-inch-diameter jet nozzle.

  17. Structural and electronic dependence of the single-molecule-magnet behavior of dysprosium(III) complexes.

    PubMed

    Campbell, Victoria E; Bolvin, Hélène; Rivière, Eric; Guillot, Regis; Wernsdorfer, Wolfgang; Mallah, Talal

    2014-03-03

    We investigate and compare the magnetic properties of two isostructural Dy(III)-containing complexes. The Dy(III) ions are chelated by hexadentate ligands and possess two apical bidendate nitrate anions. In dysprosium(III) N,N'-bis(imine-2-yl)methylene-1,8-diamino-3,6-dioxaoctane (1), the ligand's donor atoms are two alkoxo, two pyridine, and two imine nitrogen atoms. Dysprosium(III) N,N'-bis(amine-2-yl)methylene-1,8-diamino-3,6-dioxaoctane (2) is identical with 1 except for one modification: the two imine groups have been replaced by amine groups. This change has a minute effect on the structure and a larger effect the magnetic behavior. The two complexes possess slow relaxation of the magnetization in the presence of an applied field of 1000 Oe but with a larger barrier for reorientation of the magnetization for 1 (Ueff/kB = 50 K) than for 2 (Ueff/kB = 34 K). First-principles calculations using the spin-orbit complete active-space self-consistent-field method were performed and allowed to fit the experimental magnetization data. The calculations gave the energy spectrum of the 2J + 1 sublevels issued from the J = 15/2 free-ion ground state. The lowest-lying sublevels were found to have a large contribution of MJ = ±15/2 for 1, while for 2, MJ = ±13/2 was dominant. The observed differences were attributed to a synergistic effect between the electron density of the ligand and the small structural changes provoked by a slight alteration of the coordination environment. It was observed that the stronger ligand field (imine) resulted in complex 1 with a larger energy barrier for reorientation of the magnetization than 2.

  18. Interaction of curcumin with Al(III) and its complex structures based on experiments and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Jiang, Teng; Wang, Long; Zhang, Sui; Sun, Ping-Chuan; Ding, Chuan-Fan; Chu, Yan-Qiu; Zhou, Ping

    2011-10-01

    Curcumin has been recognized as a potential natural drug to treat the Alzheimer's disease (AD) by chelating baleful metal ions, scavenging radicals and preventing the amyloid β (Aβ) peptides from the aggregation. In this paper, Al(III)-curcumin complexes with Al(III) were synthesized and characterized by liquid-state 1H, 13C and 27Al nuclear magnetic resonance (NMR), mass spectroscopy (MS), ultraviolet spectroscopy (UV) and generalized 2D UV-UV correlation spectroscopy. In addition, the density functional theory (DFT)-based UV and chemical shift calculations were also performed to view insight into the structures and properties of curcumin and its complexes. It was revealed that curcumin could interact strongly with Al(III) ion, and form three types of complexes under different molar ratios of [Al(III)]/[curcumin], which would restrain the interaction of Al(III) with the Aβ peptide, reducing the toxicity effect of Al(III) on the peptide.

  19. III-V strain layer superlattice based band engineered avalanche photodiodes (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Ghosh, Sid

    2015-08-01

    Laser detection and ranging (LADAR)-based systems operating in the Near Infrared (NIR) and Short Wave Infrared (SWIR) have become popular optical sensors for remote sensing, medical, and environmental applications. Sophisticated laser-based radar and weapon systems used for long-range military and astronomical applications need to detect, recognize, and track a variety of targets under a wide spectrum of atmospheric conditions. Infrared APDs play an important role in LADAR systems by integrating the detection and gain stages in a single device. Robust silicon-APDs are limited to visible and very near infrared region (< 1 um), while InGaAs works well up to wavelengths of about 1.5um. Si APDs have low multiplication or excess noise but are limited to below 1um due very poor quantum efficiency above 0.8um. InGaAs and Ge APDs operate up to wavelengths of 1.5um but have poor multiplication or excess noise due to a low impact ionization coefficient ratio between electrons and holes. For the past several decades HgCdTe has been traditionally used in longer wavelength (> 3um) infrared photon detection applications. Recently, various research groups (including Ghosh et. al.) have reported SWIR and MWIR HgCdTe APDs on CdZnTe and Si substrates. However, HgCdTe APDs suffer from low breakdown fields due to material defects, and excess noise increases significantly at high electric fields. During the past decade, InAs/GaSb Strain Layer Superlattice (SLS) material system has emerged as a potential material for the entire infrared spectrum because of relatively easier growth, comparable absorption coefficients, lower tunneling currents and longer Auger lifetimes resulting in enhanced detectivities (D*). Band engineering in type II SLS allows us to engineer avalanche properties of electrons and holes. This is a great advantage over bulk InGaAs and HgCdTe APDs where engineering avalanche properties is not possible. The talk will discuss the evolution of superlattice based avalanche

  20. Structurally compliant rocket engine combustion chamber: Experimental and analytical validation

    NASA Technical Reports Server (NTRS)

    Jankovsky, Robert S.; Arya, Vinod K.; Kazaroff, John M.; Halford, Gary R.

    1994-01-01

    A new, structurally compliant rocket engine combustion chamber design has been validated through analysis and experiment. Subscale, tubular channel chambers have been cyclically tested and analytically evaluated. Cyclic lives were determined to have a potential for 1000 percent increase over those of rectangular channel designs, the current state of the art. Greater structural compliance in the circumferential direction gave rise to lower thermal strains during hot firing, resulting in lower thermal strain ratcheting and longer predicted fatigue lives. Thermal, structural, and durability analyses of the combustion chamber design, involving cyclic temperatures, strains, and low-cycle fatigue lives, have corroborated the experimental observations.

  1. Engineering the Electronic Band Structure for Multiband Solar Cells

    SciTech Connect

    Lopez, N.; Reichertz, L.A.; Yu, K.M.; Campman, K.; Walukiewicz, W.

    2010-07-12

    Using the unique features of the electronic band structure of GaNxAs1-x alloys, we have designed, fabricated and tested a multiband photovoltaic device. The device demonstrates an optical activity of three energy bands that absorb, and convert into electrical current, the crucial part of the solar spectrum. The performance of the device and measurements of electroluminescence, quantum efficiency and photomodulated reflectivity are analyzed in terms of the Band Anticrossing model of the electronic structure of highly mismatched alloys. The results demonstrate the feasibility of using highly mismatched alloys to engineer the semiconductor energy band structure for specific device applications.

  2. Engineering the electronic band structure for multiband solar cells.

    PubMed

    López, N; Reichertz, L A; Yu, K M; Campman, K; Walukiewicz, W

    2011-01-14

    Using the unique features of the electronic band structure of GaN(x)As(1-x) alloys, we have designed, fabricated and tested a multiband photovoltaic device. The device demonstrates an optical activity of three energy bands that absorb, and convert into electrical current, the crucial part of the solar spectrum. The performance of the device and measurements of electroluminescence, quantum efficiency and photomodulated reflectivity are analyzed in terms of the band anticrossing model of the electronic structure of highly mismatched alloys. The results demonstrate the feasibility of using highly mismatched alloys to engineer the semiconductor energy band structure for specific device applications.

  3. Structures and Luminescent Properties of Two 2D Coordination Polymers Containing Tb(III) or Dy(III) Ions.

    PubMed

    An, Xiaoping; Wang, Hongsheng; Li, Gongchun

    2014-03-01

    Two 2D rare earth terbium and dysprosium coordination polymers with 2,4-pyridinedicarboxylate and oxalate anions have been synthesized by hydrothermal method, the formula is {[RE(pda)(ox)0.5(H2O)4]·2H2O}n (RE = Tb (1) and Dy (2); H2pda = 2,4-pyridinedicarboxylic acid; ox = oxalate anion). The two complexes are isomorphic and crystallized in monoclinic system, P21/c space group. Each pda anion connects two rare earth ions with 2- carboxyl group and the nitrogen atom but the 4- carboxyl group does not coordinate with rare earth ions. Each ox anion connects two rare earth ions by μ 2-bridge way. Both the complexes exhibit intense characteristic luminescence of Tb(III) or Dy(III) ion with excitation of UV-rays.

  4. NCN-chelated organoantimony(III) and organobismuth(III) phosphates: synthesis and solid-state and solution structures.

    PubMed

    Svoboda, Tomáš; Dostál, Libor; Jambor, Roman; Růžička, Aleš; Jirásko, Robert; Lyčka, Antonín

    2011-07-18

    .Organoantimony(III) and organobismuth(III) phosphates (LM)(3)(PO(4))(2) [M = Sb (3) and Bi (4)], containing the NCN-chelating ligand L [L = 2,6-(CH(2)NMe(2))(2)C(6)H(3)], were prepared by the simple treatment of parent oxides 1 and 2 with H(3)PO(4). Both compounds were characterized by elemental analysis, electrospray ionization mass spectrometry, and IR and NMR spectroscopy and in the case of 3 by X-ray diffraction techniques. Compound 3 has an interesting behavior in solution, i.e., the formation of two possible conformational isomers, which was studied by (1)H, (13)C, and (31)P NMR spectroscopy.

  5. Cabin-fuselage-wing structural design concept with engine installation

    NASA Technical Reports Server (NTRS)

    Ariotti, Scott; Garner, M.; Cepeda, A.; Vieira, J.; Bolton, D.

    1993-01-01

    The purpose of this project is to provide a fuselage structural assembly and wing structural design that will be able to withstand the given operational parameters and loads provided by Federal Aviation Regulation Part 23 (FAR 23) and the Statement of Work (SOW). The goal is to provide a durable lightweight structure that will transfer the applied loads through the most efficient load path. Areas of producibility and maintainability of the structure will also be addressed. All of the structural members will also meet or exceed the desired loading criteria, along with providing adequate stiffness, reliability, and fatigue life as stated in the SOW. Considerations need to be made for control system routing and cabin heating/ventilation. The goal of the wing structure and carry through structure is also to provide a simple, lightweight structure that will transfer the aerodynamic forces produced by the wing, tailboom, and landing gear. These forces will be channeled through various internal structures sized for the pre-determined loading criteria. Other considerations were to include space for flaps, ailerons, fuel tanks, and electrical and control system routing. The difficulties encountered in the fuselage design include expanding the fuselage cabin to accept a third occupant in a staggered configuration and providing ample volume for their safety. By adding a third person the CG of aircraft will move forward so the engine needs to be moved aft to compensate for the difference in the moment. This required the provisions of a ring frame structure for the new position of the engine mount. The difficulties encountered in the wing structural design include resizing the wing for the increased capacity and weight, and compensating for a large torsion produced by the tail boom by placing a great number of stiffeners inside the boom, which will result in the relocation of the fuel tank. Finally, an adequate carry through structure for the wing and fuselage interface will be

  6. Syntheses, structures, and magnetic properties of a family of heterometallic heptanuclear [Cu5Ln2] (Ln = Y(III), Lu(III), Dy(III), Ho(III), Er(III), and Yb(III)) complexes: observation of SMM behavior for the Dy(III) and Ho(III) analogues.

    PubMed

    Chandrasekhar, Vadapalli; Dey, Atanu; Das, Sourav; Rouzières, Mathieu; Clérac, Rodolphe

    2013-03-04

    Sequential reaction of the multisite coordination ligand (LH3) with Cu(OAc)2·H2O, followed by the addition of a rare-earth(III) nitrate salt in the presence of triethylamine, afforded a series of heterometallic heptanuclear complexes containing a [Cu5Ln2] core {Ln = Y(1), Lu(2), Dy(3), Ho(4), Er(5), and Yb(6)}. Single-crystal X-ray crystallography reveals that all the complexes are dicationic species that crystallize with two nitrate anions to compensate the charge. The heptanuclear aggregates in 1-6 are centrosymmetrical complexes, with a hexagonal-like arrangement of six peripheral metal ions (two rare-earth and four copper) around a central Cu(II) situated on a crystallographic inversion center. An all-oxygen environment is found to be present around the rare-earth metal ions, which adopt a distorted square-antiprismatic geometry. Three different Cu(II) sites are present in the heptanuclear complexes: two possess a distorted octahedral coordination sphere while the remaining one displays a distorted square-pyramidal geometry. Detailed static and dynamic magnetic properties of all the complexes have been studied and revealed the single-molecule magnet behavior of the Dy(III) and Ho(III) derivatives.

  7. Impacts of engineered nanomaterials on microbial community structure and function in natural and engineered ecosystems.

    PubMed

    Mohanty, Anee; Wu, Yichao; Cao, Bin

    2014-10-01

    In natural and engineered environments, microorganisms often exist as complex communities, which are key to the health of ecosystems and the success of bioprocesses in various engineering applications. With the rapid development of nanotechnology in recent years, engineered nanomaterials (ENMs) have been considered one type of emerging contaminants that pose great potential risks to the proper function of microbial communities in natural and engineered ecosystems. The impacts of ENMs on microorganisms have attracted increasing research attentions; however, most studies focused on the antimicrobial activities of ENMs at single cell and population level. Elucidating the influence of ENMs on microbial communities represents a critical step toward a comprehensive understanding of the ecotoxicity of ENMs. In this mini-review, we summarize and discuss recent research work on the impacts of ENMs on microbial communities in natural and engineered ecosystems, with an emphasis on their influences on the community structure and function. We also highlight several important research topics which may be of great interest to the research community.

  8. Crystal structures of two ytterbium(III) complexes comprising alkynylamidinate ligands

    PubMed Central

    Wang, Sida; Sroor, Farid M.; Liebing, Phil; Lorenz, Volker; Hilfert, Liane; Edelmann, Frank T.

    2016-01-01

    Two ytterbium(III) complexes comprising alkynylamidinate ligands, namely bis­(η5-cyclo­penta­dien­yl)(3-cyclo­propyl-N,N′-diiso­propyl­propynamidinato-κ2 N,N′)ytterbium(III), [Yb(C5H5)2(C12H19N2)] or Cp2Yb[(iPr2N)2C—C≡C—c-C3H5] (1) and tris­(3-phenyl-N,N′-di­cyclo­hexyl­propynamidinato-κ2 N,N′)ytterbium(III), [Yb(C21H27N2)3] or Yb[(CyN)2C—C≡C—Ph]3 (Cy = cyclo­hex­yl) (2) have been synthesized and structurally characterized. Both complexes are monomers; for complex 2, the contribution to the scattering from highly disordered toluene solvent molecules in these voids was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON. The stated crystal data for Mr, μ etc. do not take these into account. PMID:27920904

  9. Crystal structures of two ytterbium(III) complexes comprising alkynylamidinate ligands.

    PubMed

    Wang, Sida; Sroor, Farid M; Liebing, Phil; Lorenz, Volker; Hilfert, Liane; Edelmann, Frank T

    2016-09-01

    Two ytterbium(III) complexes comprising alkynylamidinate ligands, namely bis-(η(5)-cyclo-penta-dien-yl)(3-cyclo-propyl-N,N'-diiso-propyl-propynamidinato-κ(2)N,N')ytterbium(III), [Yb(C5H5)2(C12H19N2)] or Cp2Yb[( (i) Pr2N)2C-C≡C-c-C3H5] (1) and tris-(3-phenyl-N,N'-di-cyclo-hexyl-propynamidinato-κ(2)N,N')ytterbium(III), [Yb(C21H27N2)3] or Yb[(CyN)2C-C≡C-Ph]3 (Cy = cyclo-hex-yl) (2) have been synthesized and structurally characterized. Both complexes are monomers; for complex 2, the contribution to the scattering from highly disordered toluene solvent molecules in these voids was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9-18] in PLATON. The stated crystal data for Mr, μ etc. do not take these into account.

  10. New lipophilic 3-hydroxy-4-pyridinonate iron(III) complexes: synthesis and EXAFS structural characterisation.

    PubMed

    Schlindwein, Walkiria; Waltham, Emma; Burgess, John; Binsted, Norman; Nunes, Ana; Leite, Andreia; Rangel, Maria

    2006-03-14

    New tris-iron(III) chelates of 3-hydroxy-4-pyridinone ligands derived from maltol (3-hydroxy-2-methyl-4-pyrone) or ethylmaltol (2-ethyl-3-hydroxy-4-pyrone), including a variety of N-aryl (phenyl, 4'-tolyl, 4'-(n-butyl)phenyl, 4'-(n-hexyl)phenyl) and N-benzyl (4'-methylbenzyl, 4'-fluorobenzyl and 4'-(trifluoromethyl)benzylamine) substituents on the nitrogen atom of the pyridinone ring, have been prepared. Characterization by C,H,N elemental analysis and thermogravimetric measurements indicates that most of the complexes are obtained as hydrates of general formula ML3.xH2O. Structural characterization of these difficult to crystallize lipophilic complexes has been achieved by EXAFS spectroscopy. Solutions of iron(III) complexes of maltol, ethylmaltol, 1,2-dimethyl-3-hydroxy-4-pyridinone and 1-phenyl-2-methyl-3-hydroxy-4-pyridinone in methanol-water mixtures were also examined by EXAFS. Distances from the central atom to ligand atoms, within 6 A of the metal, have been determined in the solid and solution samples and the results show that the structure observed in the powder is maintained in solution. The local structure around the metal centre, bond distances and bond angles, does not change significantly with variable lipophilicity, thus indicating that ligands may be tailored according to specific needs without altering their chelation properties. EXAFS data analysis for this set of tris-iron(III) compounds illustrates the important contribution of both intra-ligand and inter-ligand multiple scattering pathways through the metal centre to a peak observed in the FT spectrum at twice the metal ligand distance (approximately 4 A). The present results demonstrate that EXAFS features at twice the metal-ligand distance are valuable in the assignment of molecular geometry and that location of hydration water molecules, by EXAFS analysis, is limited by the geometry of the complexes, in particular for those in which ligands containing phenyl rings are present.

  11. Fourier Analysis and Structure Determination--Part III: X-ray Crystal Structure Analysis.

    ERIC Educational Resources Information Center

    Chesick, John P.

    1989-01-01

    Discussed is single crystal X-ray crystal structure analysis. A common link between the NMR imaging and the traditional X-ray crystal structure analysis is reported. Claims that comparisons aid in the understanding of both techniques. (MVL)

  12. Engineering development of coal-fired high performance power systems, Phase II and III

    SciTech Connect

    1998-07-01

    The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: thermal efficiency (HHV) {ge} 47%, NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard), coal providing {ge} 65% of heat input, all solid wastes benign cost of electricity {le} 90% of present plants. Phase 1, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase 1 also included preliminary R and D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. This phase, Phase 2, involves the development and testing of plant subsystems, refinement and updating of the HIPPS commercial plant design, and the site selection and engineering design of a HIPPS prototype plant. Work reported herein is from: Task 2.1 HITAF Combustor; Task 2.2 HITAF Air Heaters; Task 6 HIPPS Commercial Plant Design Update.

  13. Engineering development of coal-fired high performance power systems, Phase II and III

    SciTech Connect

    1999-01-01

    The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: thermal efficiency (HHV) {ge} 47%; NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard) coal providing {ge} 65% of heat input; all solid wastes benign; cost of electricity {le} 90% of present plants. Phase 1, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase 1 also included preliminary R and D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. This phase, Phase 2, involves the development and testing of plant subsystems, refinement and updating of the HIPPS commercial plant design, and the site selection and engineering design of a HIPPS prototype plant. Work reported herein is from: Task 2.1 HITAC Combustors; Task 2.2 HITAF Air Heaters; Task 6 HIPPS Commercial Plant Design Update.

  14. Synthesis, Structural and Spectroscopic Characterization, and Reactivities of Mononuclear Cobalt(III)-Peroxo Complexes

    PubMed Central

    Cho, Jaeheung; Sarangi, Ritimukta; Kang, Hye Yeon; Lee, Jung Yoon; Kubo, Minoru; Ogura, Takashi; Solomon, Edward I.; Nam, Wonwoo

    2010-01-01

    Metal-dioxygen adducts are key intermediates detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. In this study, mononuclear cobalt(III)- peroxo complexes bearing tetraazamacrocyclic ligands, [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+, were synthesized by reacting [Co(12-TMC)(CH3CN)]2+ and [Co(13-TMC)(CH3CN)]2+, respectively, with H2O2 in the presence of triethylamine. The mononuclear cobalt(III)-peroxo intermediates were isolated and characterized by various spectroscopic techniques and X-ray crystallography, and the structural and spectroscopic characterization demonstrated unambiguously that the peroxo ligand is bound in a side-on η2 fashion. The O-O bond stretching frequency of [Co(12-TMC)(O2)]+ and [Co(13- TMC)(O2)]+ was determined to be 902 cm−1 by resonance Raman spectroscopy. The structural properties of the CoO2 core in both complexes are nearly identical; the O-O bond distances of [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+ were 1.4389(17) Å and 1.438(6) Å, respectively. The cobalt(III)-peroxo complexes showed reactivities in the oxidation of aldehydes and O2-transfer reactions. In the aldehyde oxidation reactions, the nucleophilic reactivity of the cobalt-peroxo complexes was significantly dependent on the ring size of the macrocyclic ligands, with the reactivity of [Co(13-TMC)(O2)]+ > [Co(12-TMC)(O2)]+. In the O2-transfer reactions, the cobalt(III)-peroxo complexes transferred the bound peroxo group to a manganese(II) complex, affording the corresponding cobalt(II) and manganese(III)- peroxo complexes. The reactivity of the cobalt-peroxo complexes in O2-transfer was also significantly dependent on the ring size of tetraazamacrocycles, and the reactivity order in the O2-transfer reactions was the same as that observed in the aldehyde oxidation reactions. PMID:21062059

  15. Fatty acid biosynthesis revisited: structure elucidation and metabolic engineering.

    PubMed

    Beld, Joris; Lee, D John; Burkart, Michael D

    2015-01-01

    Fatty acids are primary metabolites synthesized by complex, elegant, and essential biosynthetic machinery. Fatty acid synthases resemble an iterative assembly line, with an acyl carrier protein conveying the growing fatty acid to necessary enzymatic domains for modification. Each catalytic domain is a unique enzyme spanning a wide range of folds and structures. Although they harbor the same enzymatic activities, two different types of fatty acid synthase architectures are observed in nature. During recent years, strained petroleum supplies have driven interest in engineering organisms to either produce more fatty acids or specific high value products. Such efforts require a fundamental understanding of the enzymatic activities and regulation of fatty acid synthases. Despite more than one hundred years of research, we continue to learn new lessons about fatty acid synthases' many intricate structural and regulatory elements. In this review, we summarize each enzymatic domain and discuss efforts to engineer fatty acid synthases, providing some clues to important challenges and opportunities in the field.

  16. Fatty acid biosynthesis revisited: Structure elucidation and metabolic engineering

    SciTech Connect

    Beld, Joris; Lee, D. John; Burkart, Michael D.

    2014-10-20

    Fatty acids are primary metabolites synthesized by complex, elegant, and essential biosynthetic machinery. Fatty acid synthases resemble an iterative assembly line, with an acyl carrier protein conveying the growing fatty acid to necessary enzymatic domains for modification. Each catalytic domain is a unique enzyme spanning a wide range of folds and structures. Although they harbor the same enzymatic activities, two different types of fatty acid synthase architectures are observed in nature. During recent years, strained petroleum supplies have driven interest in engineering organisms to either produce more fatty acids or specific high value products. Such efforts require a fundamental understanding of the enzymatic activities and regulation of fatty acid synthases. Despite more than one hundred years of research, we continue to learn new lessons about fatty acid synthases' many intricate structural and regulatory elements. Lastly, in this review, we summarize each enzymatic domain and discuss efforts to engineer fatty acid synthases, providing some clues to important challenges and opportunities in the field.

  17. Fatty Acid Biosynthesis Revisited: Structure Elucidation and Metabolic Engineering

    PubMed Central

    Beld, Joris; Lee, D. John

    2014-01-01

    Fatty acids are primary metabolites synthesized by complex, elegant, and essential biosynthetic machinery. Fatty acid synthases resemble an iterative assembly line, with an acyl carrier protein conveying the growing fatty acid to necessary enzymatic domains for modification. Each catalytic domain is a unique enzyme spanning a wide range of folds and structures. Although they harbor the same enzymatic activities, two different types of fatty acid synthase architectures are observed in nature. During recent years, strained petroleum supplies have driven interest in engineering organisms to either produce more fatty acids or specific high value products. Such efforts require a fundamental understanding of the enzymatic activities and regulation of fatty acid synthases. Despite more than one hundred years of research, we continue to learn new lessons about fatty acid synthases’ many intricate structural and regulatory elements. In this review, we summarize each enzymatic domain and discuss efforts to engineer fatty acid synthases, providing some clues to important challenges and opportunities in the field. PMID:25360565

  18. Structure of Salmonella FlhE, conserved member of a flagellar Type III secretion operon

    DOE PAGES

    Lee, Jaemin; Monzingo, Arthur F.; Keatinge-Clay, Adrian T.; ...

    2014-12-26

    In this paper, the bacterial flagellum is assembled by a multicomponent transport apparatus categorized as a type III secretion system. The secretion of proteins that assemble into the flagellum is driven by the proton motive force. The periplasmic protein FlhE is a member of the flhBAE operon in the majority of bacteria where FlhE is found. FlhA and FlhB are established components of the flagellar type III secretion system. The absence of FlhE results in a proton leak through the flagellar system, inappropriate secretion patterns, and cell death, indicating that FlhE regulates an important aspect of proper flagellar biosynthesis. Wemore » isolated FlhE from the periplasm of Salmonella and solved its structure to 1.5 Å resolution. The structure reveals a β-sandwich fold, with no close structural homologs. Finally, possible roles of FlhE, including that of a chaperone, are discussed.« less

  19. Biology of Budding Bacteria III. Fine Structure of Rhodomicrobium and Hyphomicrobium spp

    PubMed Central

    Conti, S. F.; Hirsch, Peter

    1965-01-01

    Conti, S. F. (Dartmouth Medical School, Hanover, N.H.), and Peter Hirsch. Biology of budding bacteria. III. Fine structure of Rhodomicrobium and Hyphomicrobium spp. J. Bacteriol. 89:503–512. 1965.—The ultrastructure of 14 strains of hyphomicrobia, and of Rhodomicrobium vannielii, was investigated by means of electron microscopy of thin sections. The majority of the strains of hyphomicrobia possessed a well-developed internal membrane system, which appeared to be derived by invagination from the cytoplasmic membrane. The subcellular organization of the hyphomicrobia and R. vannielii was investigated. Images PMID:14255720

  20. Nitroxylcob(III)Alamin: Synthesis And X-Ray Structural Characterization

    SciTech Connect

    Hannibal, L.; Smith, C.A.; Jacobsen, D.W.; Brasch, N.E.

    2009-06-01

    The long-elusive crystal structure of nitrosylcobalamin (NOCbl) reveals that the Co-N-O angle is 117.4-121.4{sup o}; hence, NOCbl is best described as nitroxylcob(III)alamin in the solid state (see picture: Co purple, N blue, O red, P orange, C gray, H white). The length of the Co-N bond trans to the NO ligand is typical of those seen when strong {beta}-axial ligands are positioned trans to the 5,6-dimethylbenzimidazole group.

  1. Advanced stress analysis methods applicable to turbine engine structures

    NASA Technical Reports Server (NTRS)

    Pian, T. H. H.

    1985-01-01

    Advanced stress analysis methods applicable to turbine engine structures are investigated. Constructions of special elements which containing traction-free circular boundaries are investigated. New versions of mixed variational principle and version of hybrid stress elements are formulated. A method is established for suppression of kinematic deformation modes. semiLoof plate and shell elements are constructed by assumed stress hybrid method. An elastic-plastic analysis is conducted by viscoplasticity theory using the mechanical subelement model.

  2. Phytases: crystal structures, protein engineering and potential biotechnological applications.

    PubMed

    Yao, M-Z; Zhang, Y-H; Lu, W-L; Hu, M-Q; Wang, W; Liang, A-H

    2012-01-01

    Phytases are a group of enzymes capable of releasing phosphates from phytates, one of the major forms of phosphorus (P) in animal feeds of plant origin. These enzymes have been widely used in animal feed to improve phosphorus nutrition and to reduce phosphorus pollution in animal waste. This review covers the basic nomenclature and crystal structures of phytases and emphasizes both the protein engineering strategies used for the development of new, effective phytases with improved properties and the potential biotechnological applications of phytases.

  3. Structured electron beams from nano-engineered cathodes

    NASA Astrophysics Data System (ADS)

    Lueangaramwong, A.; Mihalcea, D.; Andonian, G.; Piot, P.

    2017-03-01

    The ability to engineer cathodes at the nano-scale have opened new possibilities such as enhancing quantum efficiency via surface-plasmon excitation, forming ultra-low-emittance beams, or producing structured electron beams. In this paper, we present numerical investigations of the beam dynamics associated with this class of cathode in the weak- and strong-field regimes. We finally discuss the possible applications of some of the achievable cathode patterns when coupled with other phase space manipulations.

  4. Synthesis and crystal structure of Ru III-supported tungstoantimonate [Sb 2W 20Ru III2(H 2O) 2(dmso) 6O 68] 4-

    NASA Astrophysics Data System (ADS)

    Bi, Li-Hua; Li, Bao; Bi, Shuai; Wu, Li-Xin

    2009-06-01

    The first Ru III-supported tungstoantimonate [Ru II(bpy) 3] 2[Sb 2W 20Ru III2(H 2O) 2(dmso) 6O 68]·3dmso (bpy=bi-pyridine) ( 1a) has been successfully isolated as [Ru(bpy) 3] 2+ (Rubpy) salt by routine synthetic reaction in mixed solutions with dmso and water. Single-crystal X-ray analysis was carried out on 1a, which crystallizes in the triclinic system space group P-1 with a=16.804 (6), b=16.988 (6), c=17.666 (6) Å, α=107.397 (13)°, β=106.883 (13)°, γ=103.616 (12)°. V=4309 (3) Å 3, Z=1 with R1=0.0773. The compound 1a reveals the following features: (1) Rubpy is firstly used as an alternative ruthenium-source for the synthesis of Ru-substituted heteropolytungstate; (2) the structure of 1a consists of four Ru III-O-S(CH 3) 2 and two W-O-S(CH 3) 2 bonds resulting in an assembly with C2 symmetry; (3) the Ru III ions are linked to two dmso groups via two Ru III-O-S(CH 3) 2 bonds, which represents the other dmso-coordination mode to Ru III in POM chemistry. The cyclic voltammetry studies of 1a in dmso/H 2SO 4 (3/1 v/v) at pH 2.5 medium using the glassy carbon electrode as a working electrode show the respective electrochemical behaviors of the W-centers and the Ru-centers within 1a, which could be separated clearly. In addition, the compound 1a exhibits photoluminescence arising from π*- t2g ligand-to-metal transition of Rubpy.

  5. Note: Comparison of grazing incidence small angle x-ray scattering of a titania sponge structure at the beamlines BW4 (DORIS III) and P03 (PETRA III)

    SciTech Connect

    Rawolle, M.; Koerstgens, V.; Ruderer, M. A.; Metwalli, E.; Guo, S.; Mueller-Buschbaum, P.; Herzog, G.; Benecke, G.; Schwartzkopf, M.; Buffet, A.; Perlich, J.; Roth, S. V.

    2012-10-15

    Grazing incidence small angle x-ray scattering (GISAXS) is a powerful technique for morphology investigation of nanostructured thin films. GISAXS measurements at the newly installed P03 beamline at the storage ring PETRA III in Hamburg, Germany, are compared to the GISAXS data from the beamline BW4 at the storage ring DORIS III, which had been used extensively for GISAXS investigations in the past. As an example, a titania thin film sponge structure is investigated. Compared to BW4, at beamline P03 the resolution of larger structures is slightly improved and a higher incident flux leads to a factor of 750 in scattered intensity. Therefore, the acquisition time in GISAXS geometry is reduced significantly at beamline P03.

  6. Ferroelectric domain engineering and micro-structuring of lithium niobate

    NASA Astrophysics Data System (ADS)

    Mailis, Sakellaris

    2010-11-01

    This paper discusses a number of recently developed all optical and optically assisted methods for ferroelectric domain engineering in lithium niobate and their impact on the micro-structuring of this optical ferroelectric crystal. Optical radiation is used to change the response of lithium niobate crystals to externally applied electric field encouraging or inhibiting ferroelectric domain inversion in a simultaneous or latent manner. Optically assisted poling processes have the advantage of producing ferroelectric domains with arbitrary shapes free from crystal symmetry restrictions which is very important for fabricating surface micro/nano-structures in this material.

  7. Active Narrow-Band Vibration Isolation of Large Engineering Structures

    NASA Technical Reports Server (NTRS)

    Rahman, Zahidul; Spanos, John

    1994-01-01

    We present a narrow-band tracking control method using a variant of the Least Mean Squares (LMS) algorithm to isolate slowly changing periodic disturbances from engineering structures. The advantage of the algorithm is that it has a simple architecture and is relatively easy to implement while it can isolate disturbances on the order of 40-50 dB over decades of frequency band. We also present the results of an experiment conducted on a flexible truss structure. The average disturbance rejection achieved is over 40 dB over the frequency band of 5 Hz to 50 Hz.

  8. Structural dynamic testing of the Engineering Test Satellite-IV

    NASA Astrophysics Data System (ADS)

    Shiraki, K.; Mitsuma, H.; Matsushita, T.; Izumi, H.

    The Engineering Test Satellite-IV (ETS-IV) was the first large scale spacecraft developed and launched successfully in Japan on a new N-II launch vehicle. This paper presents an approach taken for the structural development of the ETS-IV. Extensive structural tests were performed to demonstrate that the ETS-IV spacecraft meets all design requirements and will survive all critical environments. Details of the static load test, vibration tests, acoustic test, and pyrotechnic shock test were described. The test results were compared with analyses and measured flight data.

  9. Harnessing natural product assembly lines: structure, promiscuity, and engineering

    PubMed Central

    Ladner, Christopher C; Williams, Gavin J

    2015-01-01

    Many therapeutically relevant natural products are biosynthesized by the action of giant mega-enzyme assembly lines. By leveraging the specificity, promiscuity, and modularity of assembly lines, a variety of strategies have been developed that enable the biosynthesis of modified natural products. This review briefly summarizes recent structural advances related to natural product assembly lines, discusses chemical approaches to probing assembly line structures in the absence of traditional biophysical data, and surveys efforts that harness the inherent or engineered promiscuity of assembly lines for the synthesis of non-natural polyketides and nonribosomal peptide analogues. PMID:26527577

  10. Engineered biosynthesis of plant polyketides: structure-based and precursor-directed approach.

    PubMed

    Abe, Ikuro

    2010-01-01

    Pentaketide chromone synthase (PCS) and octaketide synthase (OKS) are novel plant-specific type III polyketide synthases (PKSs) obtained from Aloe arborescens. Recombinant PCS expressed in Escherichia coli catalyzes iterative condensations of five molecules of malonyl-CoA to produce a pentaketide 5,7-dihydroxy-2-methylchromone, while recombinant OKS carries out sequential condensations of eight molecules of malonyl-CoA to yield octaketides SEK4 and SEK4b, the longest polyketides produced by the structurally simple type III PKS. The amino acid sequences of PCS and OKS are 91% identical, sharing 50-60% identity with those of other chalcone synthase (CHS) superfamily type III PKSs of plant origin. One of the most characteristic features is that the conserved active-site Thr197 of CHS (numbering in Medicago sativa CHS) is uniquely replaced with Met207 in PCS and with Gly207 in OKS, respectively. Site-directed mutagenesis and X-ray crystallographic analyses demonstrated that the chemically inert single residue lining the active-site cavity controls the polyketide chain length and the product specificity depending on the steric bulk of the side chain. On the basis of the crystal structures, an F80A/Y82A/M207G triple mutant of the pentaketide-producing PCS was constructed and shown to catalyze condensations of nine molecules of malonyl-CoA to produce an unnatural novel nonaketide naphthopyrone, whereas an N222G mutant of the octaketides-producing OKS yielded a decaketide benzophenone SEK15 from ten molecules of malonyl-CoA. On the other hand, the type III PKSs exhibited broad substrate specificities and catalytic potential. OKS accepted p-coumaroyl-CoA as a starter substrate to produce an unnatural novel C19 hexaketide stilbene and a C21 heptaketide chalcone. Remarkably, the C21 chalcone-forming activity was dramatically increased in the structure-guided OKS N222G mutant. In addition, OKS N222G mutant also yielded unnatural novel polyketides from phenylacetyl-CoA and

  11. Engineered Biosynthesis of Plant Polyketides: Structure-Based and Precursor-Directed Approach

    NASA Astrophysics Data System (ADS)

    Abe, Ikuro

    Pentaketide chromone synthase (PCS) and octaketide synthase (OKS) are novel plant-specific type III polyketide synthases (PKSs) obtained from Aloe arborescens. Recombinant PCS expressed in Escherichia coli catalyzes iterative condensations of five molecules of malonyl-CoA to produce a pentaketide 5,7-dihydroxy-2-methylchromone, while recombinant OKS carries out sequential condensations of eight molecules of malonyl-CoA to yield octaketides SEK4 and SEK4b, the longest polyketides produced by the structurally simple type III PKS. The amino acid sequences of PCS and OKS are 91% identical, sharing 50-60% identity with those of other chalcone synthase (CHS) superfamily type III PKSs of plant origin. One of the most characteristic features is that the conserved active-site Thr197 of CHS (numbering in Medicago sativa CHS) is uniquely replaced with Met207 in PCS and with Gly207 in OKS, respectively. Site-directed mutagenesis and X-ray crystallographic analyses demonstrated that the chemically inert single residue lining the active-site cavity controls the polyketide chain length and the product specificity depending on the steric bulk of the side chain. On the basis of the crystal structures, an F80A/Y82A/M207G triple mutant of the pentaketide-producing PCS was constructed and shown to catalyze condensations of nine molecules of malonyl-CoA to produce an unnatural novel nonaketide naphthopyrone, whereas an N222G mutant of the octaketides-producing OKS yielded a decaketide benzophenone SEK15 from ten molecules of malonyl-CoA. On the other hand, the type III PKSs exhibited broad substrate specificities and catalytic potential. OKS accepted p-coumaroyl-CoA as a starter substrate to produce an unnatural novel C19 hexaketide stilbene and a C21 heptaketide chalcone. Remarkably, the C21 chalcone-forming activity was dramatically increased in the structure-guided OKS N222G mutant. In addition, OKS N222G mutant also yielded unnatural novel polyketides from phenylacetyl-CoA and

  12. Intrinsic acidity of aluminum, chromium (III) and iron (III) μ 3-hydroxo functional groups from ab initio electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Rustad, James R.; Dixon, David A.; Felmy, Andrew R.

    2000-05-01

    Density functional calculations are performed on M 3(OH) 7(H 2O) 62+ and M 3O(OH) 6(H 2O) 6+ clusters for MAl, Cr(III), and Fe(III), allowing determination of the relative acidities of the μ 3-hydroxo and aquo functional groups. Contrary to previous predictions and rationalizations, Fe 3OH and Al 3OH groups have nearly the same intrinsic acidity, while Cr 3OH groups are significantly more acidic. The gas-phase acidity of the Fe 3OH site is in good agreement with the value predicted by the molecular mechanics model previously used to estimate the relative acidities of surface sites on iron oxides. [ J. R. Rustad et al. (1996)Geochim. Cosmochim. Acta 60, 1563]. Acidities of aquo functional groups were also computed for Al and Cr. The AlOH 2 site is more acidic than the Al 3OH site, whereas the Cr 3OH site is more acidic than the CrOH 2 site. These findings predict that the surface charging behavior of chromium oxides/oxyhydroxides should be distinguishable from their Fe, Al counterparts. The calculations also provide insight into why the lepidocrocite/boehmite polymorph is not observed for CrOOH.

  13. Structural integrity of engineering composite materials: a cracking good yarn.

    PubMed

    Beaumont, Peter W R; Soutis, Costas

    2016-07-13

    Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Where human life depends upon engineering ingenuity, the burden of testing to prove a 'fracture safe design' is immense. Fitness considerations for long-life implementation of large composite structures include understanding phenomena such as impact, fatigue, creep and stress corrosion cracking that affect reliability, life expectancy and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined, and takes service duty into account. However, there are conflicting aims in the complete design process of designing simultaneously for high efficiency and safety assurance throughout an economically viable lifetime with an acceptable level of risk. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  14. Structural integrity of engineering composite materials: a cracking good yarn

    PubMed Central

    Beaumont, Peter W. R.

    2016-01-01

    Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Where human life depends upon engineering ingenuity, the burden of testing to prove a ‘fracture safe design’ is immense. Fitness considerations for long-life implementation of large composite structures include understanding phenomena such as impact, fatigue, creep and stress corrosion cracking that affect reliability, life expectancy and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined, and takes service duty into account. However, there are conflicting aims in the complete design process of designing simultaneously for high efficiency and safety assurance throughout an economically viable lifetime with an acceptable level of risk. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’. PMID:27242293

  15. Synthesis, structural characterization and photoluminescence properties of a novel La(III) complex

    NASA Astrophysics Data System (ADS)

    Köse, Muhammet; Ceyhan, Gökhan; Atcı, Emine; McKee, Vickie; Tümer, Mehmet

    2015-05-01

    In this study, a novel La(III) complex [La(H2L)2(NO3)3(MeOH)] of a Schiff base ligand was synthesized and characterized by spectroscopic and analytical methods. Single crystals of the complex suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a MeOH solution of the complex which was found to crystallise as [La(H2L)2(NO3)3(MeOH)]ṡ2MeOHṡH2O. The structure was solved in monoclinic crystal system, P21/n space group with unit cell parameters a = 10.5641(11), b = 12.6661(16), c = 16.0022(17) Å, α = 67.364(2), β = 83.794(2)°, γ = 70.541(2)°, V = 1862.9(4) Å3 and Z = 2 with R final value of 0.526. In the complex, the La(III) ion is ten-coordinated by O atoms, five of which come from three nitrate ions, four from the two Schiff base ligands and one from MeOH oxygen atom. The Schiff base ligands in the structure are in a zwitter ion form with the phenolic H transferred to the imine N atom. Thermal properties of the La(III) complex were examined by thermogravimetric analysis and the complex was found to be thermally stable up to 310 °C. The Schiff base ligand and its La(II) complex were screened for their in vitro antimicrobial activity against Bacillus megaterium, Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus (Gram positive bacteria), Klebsiella pneumonia, Escherichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa (Gram negative bacteria), Candida albicans,Yarrowia lipolytica (fungus) and Saccharomyces cerevisiae (yeast). The complex shows more antimicrobial activity than the free ligand.

  16. Magnetic coupling in discrete cyano-bridged Mn(III)-Fe(III) motifs: synthesis, crystal structure, magnetic properties and theoretical study.

    PubMed

    Visinescu, Diana; Toma, Luminita Marilena; Cano, Joan; Fabelo, Oscar; Ruiz-Pérez, Catalina; Labrador, Ana; Lloret, Francesc; Julve, Miguel

    2010-05-28

    The preparation, crystal structures and magnetic properties of the heterobimetallic complexes of formula [Mn(III)(n-MeOsalen)(H(2)O)(mu-CN)Fe(III)(bpym)(CN)(3)]·mH(2)O with n = m = 3 (1) and n = 4 and m = 2 (2) [n-MeOsalen(2-) = N,N'-ethylenebis(n-methoxysalicylideneiminate) dianion and bpym = 2,2'-bipyrimidine] are reported. 1 and 2 are dinuclear neutral species where the cyano-bearing low-spin unit [Fe(III)(bpym)(CN)(4)](-) acts as a monodentate ligand towards the [Mn(III)(SB)(solv)(x)](+) entity (SB = tetradentate Schiff-base) through one of its four cyano groups. Adjacent heterobimetallic units are interlinked through hydrogen bonds involving the coordinated water molecule of one dinuclear unit and the phenolate oxygen atoms of the neighbouring one to afford pairs of dimers with values of the interdimer Mn···Mn distance of 4.925(20) (1) and 5.0508(25) Å (2). The analysis of the magnetic data of 1 and 2 in the temperature range 1.9-300 K shows the coexistence of weak ferro- [J = +2.95 (1) and +3.88 cm(-1) (2)] and antiferromagnetic interactions [j = -1.91 (1) and -0.70 cm(-1) (2)] through the single cyano bridge and hydrogen bonds, respectively (the Hamiltonian being of the type Ĥ = J[Ŝ(Fe)·Ŝ(Mn) + Ŝ(Fe')·Ŝ(Mn')] -jŜ(Mn)·Ŝ(Mn')). Theoretical calculations using methods based on density functional theory (DFT) have been used to substantiate the nature and magnitude of the magnetic coupling observed in 1 and 2 and also to analyze the dependence of the magnetic coupling on the structural parameters for the Fe-C-N-Mn skeleton. An extension of the calculations to selected examples of heterobimetallic Fe(III)-C-N-Mn(III) compounds with a different number of cyano groups on the low-spin iron(III) precursor has been carried out allowing us to illustrate the influence of the symmetry of the magnetic orbital of the iron center on the magnetic coupling in this heterobimetallic unit.

  17. Structure and Management of an Engineering Senior Design Course.

    PubMed

    Tanaka, Martin L; Fischer, Kenneth J

    2016-07-01

    The design of products and processes is an important area in engineering. Students in engineering schools learn fundamental principles in their courses but often lack an opportunity to apply these methods to real-world problems until their senior year. This article describes important elements that should be incorporated into a senior capstone design course. It includes a description of the general principles used in engineering design and a discussion of why students often have difficulty with application and revert to trial and error methods. The structure of a properly designed capstone course is dissected and its individual components are evaluated. Major components include assessing resources, identifying projects, establishing teams, understanding requirements, developing conceptual designs, creating detailed designs, building prototypes, testing performance, and final presentations. In addition to the course design, team management and effective mentoring are critical to success. This article includes suggested guidelines and tips for effective design team leadership, attention to detail, investment of time, and managing project scope. Furthermore, the importance of understanding business culture, displaying professionalism, and considerations of different types of senior projects is discussed. Through a well-designed course and proper mentoring, students will learn to apply their engineering skills and gain basic business knowledge that will prepare them for entry-level positions in industry.

  18. Synthesis and structures of a pincer-type rhodium(iii) complex: reactivity toward biomolecules.

    PubMed

    Milutinović, Milan M; Bogojeski, Jovana V; Klisurić, Olivera; Scheurer, Andreas; Elmroth, Sofi K C; Bugarčić, Živadin D

    2016-10-04

    A novel rhodium(iii) complex [Rh(III)(H2L(tBu))Cl3] (1) (H2L(tBu) = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine) containing a pincer type, tridentate nitrogen-donor chelate system was synthesized. Single crystal X-ray structure analysis revealed that 1 crystallizes in the orthorhombic space group Pbcn with a = 20.7982(6), b = 10.8952(4), c = 10.9832(4) Å, V = 2488.80(15) Å(3), and eight molecules in the unit cell. The rhodium center in the complex [Rh(III)(H2L(tBu))Cl3] (1) is coordinated in a slightly distorted octahedral geometry by the tridentate N,N,N-donor and three chloro ligands, adopting a mer arrangement with an essentially planar ligand skeleton. Due to the tridentate coordination of the N,N,N-donor, the central nitrogen atom N1 is located closer to the Rh(III) center. The reactivity of the synthesized complex toward small biomolecules (l-methionine (l-Met), guanosine-5'-monophosphate (5'-GMP), l-histidine (l-His) and glutathione (GSH)) and to a series of duplex DNAs and RNA was investigated. The order of reactivity of the studied small biomolecules is: 5'-GMP > GSH > l-Met > l-His. Duplex RNA reacts faster with the [Rh(III)(H2L(tBu))Cl3] complex than duplex DNA, while shorter duplex DNA (15mer GG) reacts faster compared with 22mer GG duplex DNA. In addition, a higher reactivity is achieved with a DNA duplex with a centrally located GG-sequence than with a 22GTG duplex DNA, in which the GG-sequence is separated by a T base. Furthermore, the interaction of this metal complex 1 with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) was examined by absorption (UV-Vis) and emission spectral studies (EthBr displacement studies). Overall, the studied complex exhibited good DNA and BSA interaction ability.

  19. From Geometry to Diagnosis: Experiences of Geomatics in Structural Engineering

    NASA Astrophysics Data System (ADS)

    Riveiro, B.; Arias, P.; Armesto, J.; Caamaño, J. C.; Solla, M.

    2012-07-01

    Terrestrial photogrammetry and laser scanning are technologies that have been successfully used for metric surveying and 3D modelling in many different fields (archaeological and architectural documentation, industrial retrofitting, mining, structural monitoring, road surveying, etc.). In the case of structural applications, these techniques have been successfully applied to 3D modelling and sometimes monitoring; but they have not been sufficiently implemented to date, as routine tools in infrastructure management systems, in terms of automation of data processing and integration in the condition assessment procedures. In this context, this paper presents a series of experiences in the usage of terrestrial photogrammetry and laser scanning in the context of dimensional and structural evaluation of structures. These experiences are particularly focused on historical masonry structures, but modern prestressed concrete bridges are also investigated. The development of methodological procedures for data collection, and data integration in some cases, is tackled for each particular structure (with access limitations, geometrical configuration, range of measurement, etc.). The accurate geometrical information provided by both terrestrial techniques motivates the implementation of such results in the complex, and sometimes slightly approximated, geometric scene that is frequently used in structural analysis. In this sense, quantitative evaluating of the influence of real and accurate geometry in structural analysis results must be carried out. As main result in this paper, a series of experiences based on the usage of photogrammetric and laser scanning to structural engineering are presented.

  20. Crystal structure of 8-iodo-quinolinium tetra-chlorido-aurate(III).

    PubMed

    Onserio, Benard O; Tamang, Sem Raj; Hoefelmeyer, James D

    2015-12-01

    The structure of the title salt, (C9H7IN)[AuCl4], is comprised of planar 8-iodo-quinolinium cations (r.m.s. deviation = 0.05 Å) and square-planar tetra-chlorido-aurate(III) anions. The asymmetric unit contains one 8-iodo-quinolinium cation and two halfs of [AuCl4](-) anions, in each case with the central Au(III) atom located on an inversion center. Inter-molecular halogen-halogen contacts were found between centrosymmetric pairs of I [3.6178 (4) Å] and Cl atoms [3.1484 (11), 3.3762 (13), and 3.4935 (12) Å]. Inter-molecular N-H⋯Cl and C-H⋯Cl hydrogen bonding is also found in the structure. These inter-actions lead to the formation of a three-dimensional network. Additionally, there is an intra-molecular N-H⋯I hydrogen bond between the aromatic iminium and iodine. There are no aurophilic inter-actions or short contacts between I and Au atoms, and there are no notable π-stacking inter-actions between the aromatic cations.

  1. On the design and structural analysis of jet engine fan blade structures

    NASA Astrophysics Data System (ADS)

    Amoo, Leye M.

    2013-07-01

    Progress in the design and structural analysis of commercial jet engine fan blades is reviewed and presented. This article is motivated by the key role fan blades play in the performance of advanced gas turbine jet engines. The fundamentals of the associated physics are emphasized. Recent developments and advancements have led to an increase and improvement in fan blade structural durability, stability and reliability. This article is intended as a high level review of the fan blade environment and current state of structural design to aid further research in developing new and innovative fan blade technologies.

  2. Distinct Structural Elements Dictate the Specificity of the Type III Pentaketide Synthase from Neurospora crassa

    SciTech Connect

    Rubin-Pitel, Sheryl B.; Zhang, Houjin; Vu, Trang; Brunzelle, Joseph S.; Zhao, Huimin; Nair, Satish K.

    2009-01-15

    The fungal type III polyketide synthase 2'-oxoalkylresorcyclic acid synthase (ORAS) primes with a range of acyl-Coenzyme A thioesters (C{sub 4}--C{sub 20}) and extends using malonyl-Coenzyme A to produce pyrones, resorcinols, and resorcylic acids. To gain insight into this unusual substrate specificity and product profile, we have determined the crystal structures of ORAS to 1.75 {angstrom} resolution, the Phe-252{yields}Gly site-directed mutant to 2.1 {angstrom} resolution, and a binary conplex of ORAS with eicosanoic acid to 2.0 {angstrom} resolution. The structures reveal a distinct rearrangement of structural elements near the active site that allows accomodation of long-chain fatty acid esters and a reorientation of the gating mechanism that controls cyclization and polyketide chain length. The roles of these structural elements are further elucidated by characterization of various structure-based site-directed variants. These studies establish an unexpected plasticity to the PKS fold, unanticipated from structural studies of other members of this enzyme family.

  3. Acoustic Detection of Faults and Degradation in a High-Bypass Turbofan Engine during VIPR Phase III Testing

    NASA Technical Reports Server (NTRS)

    Boyle, Devin K.

    2017-01-01

    The Vehicle Integrated Propulsion Research (VIPR) Phase III project was executed at Edwards Air Force Base, California, by the National Aeronautics and Space Administration and several industry, academic, and government partners in the summer of 2015. One of the research objectives was to use external radial acoustic microphone arrays to detect changes in the noise characteristics produced by the research engine during volcanic ash ingestion and seeded fault insertion scenarios involving bleed air valves. Preliminary results indicate the successful acoustic detection of suspected degradation as a result of cumulative exposure to volcanic ash. This detection is shown through progressive changes, particularly in the high-frequency content, as a function of exposure to greater cumulative quantities of ash. Additionally, detection of the simulated failure of the 14th stage stability bleed valve and, to a lesser extent, the station 2.5 stability bleed valve, to their fully-open fail-safe positions was achieved by means of spectral comparisons between nominal (normal valve operation) and seeded fault scenarios.

  4. Structural engineering of three-dimensional phononic crystals

    NASA Astrophysics Data System (ADS)

    Delpero, Tommaso; Schoenwald, Stefan; Zemp, Armin; Bergamini, Andrea

    2016-02-01

    Artificially-structured materials are attracting the research interest of a growing community of scientists for the possibility to develop novel materials with advantageous properties that arise from the ability to tailor the propagation of elastic waves, and thus energy, through them. In this work, we propose a three-dimensional phononic crystal whose unit cell has been engineered to obtain a strong wave-attenuation band in the middle of the acoustic frequency range. The combination of its acoustic properties with the dimensions of the unit cell and its static mechanical properties makes it an interesting material for possibly several applications in civil and mechanical engineering, for instance as the core of an acoustically insulating sandwich panel. A sample of this crystal has been manufactured and experimentally tested with respect to its acoustic transmissibility. The performance of the phononic crystal core is remarkable both in terms of amplitude reduction in the transmissibility and width of the attenuation band. A parametric study has been finally conducted on selected geometrical parameters of the unit cell and on their effect on the macroscopic properties of the crystal. This work represents an application-oriented example of how the macroscopic properties of an artificially-structured material can be designed, according to specific needs, by a conventional engineering of its unit cell.

  5. Simulation of Aircraft Engine Blade-Out Structural Dynamics. Revised

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Carney, Kelly; Gallardo, Vicente

    2001-01-01

    A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

  6. Simulation of Aircraft Engine Blade-Out Structural Dynamics

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Carney, Kelly; Gallardo, Vicente

    2001-01-01

    A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

  7. Extracellular matrix, mechanotransduction and structural hierarchies in heart tissue engineering.

    PubMed

    Parker, Kevin K; Ingber, Donald E

    2007-08-29

    The spatial and temporal scales of cardiac organogenesis and pathogenesis make engineering of artificial heart tissue a daunting challenge. The temporal scales range from nanosecond conformational changes responsible for ion channel opening to fibrillation which occurs over seconds and can lead to death. Spatial scales range from nanometre pore sizes in membrane channels and gap junctions to the metre length scale of the whole cardiovascular system in a living patient. Synchrony over these scales requires a hierarchy of control mechanisms that are governed by a single common principle: integration of structure and function. To ensure that the function of ion channels and contraction of muscle cells lead to changes in heart chamber volume, an elegant choreography of metabolic, electrical and mechanical events are executed by protein networks composed of extracellular matrix, transmembrane integrin receptors and cytoskeleton which are functionally connected across all size scales. These structural control networks are mechanoresponsive, and they process mechanical and chemical signals in a massively parallel fashion, while also serving as a bidirectional circuit for information flow. This review explores how these hierarchical structural networks regulate the form and function of living cells and tissues, as well as how microfabrication techniques can be used to probe this structural control mechanism that maintains metabolic supply, electrical activation and mechanical pumping of heart muscle. Through this process, we delineate various design principles that may be useful for engineering artificial heart tissue in the future.

  8. Cylinder head cover structure for a V-type engine

    SciTech Connect

    Okada, M.; Nishida, M.; Hokazono, K.

    1988-11-15

    This patent describes a cylinder head cover structure for a cylinder engine having first and second cylinder heads for forming first and second cylinder banks, each cylinder head being provided, in an inner side wall thereof, with intake ports each communicating with a cylinder formed in the cylinder bank, at least one camshaft provided in each cylinder bank above intake and exhaust valves to drive the valves in synchronization with rotation of the engine and supported for rotation by a plurality of bearings, discrete intake passages each of which is connected to one of the intake ports of one of the cylinder banks and extends above the other cylinder bank, and cylinder head covers mounted on the respective cylinder heads, characterized in that recessed portions are formed in each of the cylinder head covers at corresponding portions of the camshaft and respective the discrete intake passages extend through corresponding ones of the recessed portions.

  9. Dynamical structure of solar radio burst type III as evidence of energy of solar flares

    NASA Astrophysics Data System (ADS)

    Hamidi, Zety Sharizat Binti

    2013-11-01

    Observations of low frequency solar type III radio bursts associated with the ejection of plasma oscillations localized disturbance is due to excitation atoms in the plasma frequency incoherent radiations play a dominant role at the meter and decimeter wavelengths. Here, we report the results of the dynamical structure of solar flare type III that occurred on 9th March 2012 at National Space Centre, Sg Lang, Selangor, Malaysia by using the CALLISTO system. These bursts are associated with solar flare type M6 which suddenly ejected in the active region AR 1429 starting at 03:32 UT and ending at 05:00 UT with the peak at 04:12 UT. The observation showed an initial strong burst occurred due to strong signal at the beginning of the phase. We also found that both solar burst and flares tend to be a numerous on the same day and probability of chance coincidence is high. It is clearly seen that an impulsive lace burst was detected at 4:24 UT and it is more plausible that the energies are confined to the top of the loop when we compared with X-ray results. Associated with this event was type II with velocities 1285 km/s and type IV radio sweeps along with a full halo Coronal Mass Ejections (CMEs) first seen in SOHO/LASCO C2 imagery at 09/0426 Z. We concluded that the significance of study solar burst type III lies in the fact that the emission at decimetric wavelength comes from the role of magnetic field in active region that may provide the key to the energy release mechanism in a flare.

  10. Importance of ligand structure in DNA/protein binding, mutagenicity, excision repair and nutritional aspects of chromium(III) complexes.

    PubMed

    Vaidyanathan, V G; Asthana, Yamini; Nair, Balachandran Unni

    2013-02-21

    Chromium is extensively used in leather, chrome plating and refining industries. On one hand the occupational exposure to chromium leads to cancer, whereas on the contrary certain Cr(III) compounds have been proposed as nutritional supplements for Type II diabetes and as muscle building agents. Despite the positive outlook of chromium as a bio-essential element, there is increasing concern over the therapeutic application of Cr(III) based supplements, its bioavailability and toxicity profile. In this perspective, we discuss the role of ligand structure in mediating the interaction of chromium(III) complexes with DNA/protein, their mutagenic outcomes, adduct reparability and as nutritional supplements.

  11. Structural and phase transformation of A{sup III}B{sup V}(100) semiconductor surface in interaction with selenium

    SciTech Connect

    Bezryadin, N. N.; Kotov, G. I. Kuzubov, S. V.

    2015-03-15

    Surfaces of GaAs(100), InAs(100), and GaP(100) substrates thermally treated in selenium vapor have been investigated by transmission electron microscopy and electron probe X-ray microanalysis. Some specific features and regularities of the formation of A{sub 3}{sup III}B{sub 4}{sup VI} (100)c(2 × 2) surface phases and thin layers of gallium or indium selenides A{sub 2}{sup III}B{sub 3}{sup VI} (100) on surfaces of different A{sup III}B{sup V}(100) semiconductors are discussed within the vacancy model of surface atomic structure.

  12. Band-structure engineering in conjugated 2D polymers.

    PubMed

    Gutzler, Rico

    2016-10-26

    Conjugated polymers find widespread application in (opto)electronic devices, sensing, and as catalysts. Their common one-dimensional structure can be extended into the second dimension to create conjugated planar sheets of covalently linked molecules. Extending π-conjugation into the second dimension unlocks a new class of semiconductive polymers which as a consequence of their unique electronic properties can find usability in numerous applications. In this article the theoretical band structures of a set of conjugated 2D polymers are compared and information on the important characteristics band gap and valence/conduction band dispersion is extracted. The great variance in these characteristics within the investigated set suggests 2D polymers as exciting materials in which band-structure engineering can be used to tailor sheet-like organic materials with desired electronic properties.

  13. Structural Evaluation of Exo-Skeletal Engine Fan Blades

    NASA Technical Reports Server (NTRS)

    Kuguoglu, Latife; Abumeri, Galib; Chamis, Christos C.

    2003-01-01

    The available computational simulation capability is used to demonstrate the structural viability of composite fan blades of innovative Exo-Skeletal Engine (ESE) developed at NASA Glenn Research Center for a subsonic mission. Full structural analysis and progressive damage evaluation of ESE composite fan blade is conducted through the NASA in-house computational simulation software system EST/BEST. The results of structural assessment indicate that longitudinal stresses acting on the blade are in compression. At a design speed of 2000 rpm, pressure and suction surface outer most ply stresses in longitudinal, transverse and shear direction are much lower than the corresponding composite ply strengths. Damage is initiated at 4870 rpm and blade fracture takes place at rotor speed of 7735 rpm. Damage volume is 51 percent. The progressive damage, buckling, stress and strength results indicate that the design at hand is very sound because of the factor of safety, damage tolerance, and buckling load of 6811 rpm.

  14. STRUCTURE OF THE TYPE III PANTOTHENATE KINASE FROM Bacillus anthracis AT 2.0 Å RESOLUTION

    PubMed Central

    Nicely, Nathan I.; Parsonage, Derek; Paige, Carleitta; Newton, Gerald L.; Fahey, Robert C.; Leonardi, Roberta; Jackowski, Suzanne; Mallett, T. Conn; Claiborne, Al

    2008-01-01

    Coenzyme A (CoASH) is the major low-molecular weight thiol in Staphylococcus aureus and a number of other bacteria; the crystal structure of the S. aureus coenzyme A-disulfide reductase (CoADR), which maintains the reduced intracellular state of CoASH, has recently been reported [Mallett, T.C., Wallen, J.R., Karplus, P.A., Sakai, H., Tsukihara, T., and Claiborne, A. (2006) Biochemistry 45, 11278-11289]. In this report we demonstrate that CoASH is the major thiol in Bacillus anthracis; a bioinformatics analysis indicates that three of the four proteins responsible for the conversion of pantothenate (Pan) to CoASH in Escherichia coli are conserved in B. anthracis. In contrast, a novel type III pantothenate kinase (PanK) catalyzes the first committed step in the biosynthetic pathway in B. anthracis; unlike the E. coli type I PanK, this enzyme is not subject to feedback inhibition by CoASH. The crystal structure of B. anthracis PanK (BaPanK), solved using multiwavelength anomalous dispersion data and refined at a resolution of 2.0 Å, demonstrates that BaPanK is a new member of the Acetate and Sugar Kinase/Hsc70/Actin (ASKHA) superfamily. The Pan and ATP substrates have been modeled into the active-site cleft; in addition to providing a clear rationale for the absence of CoASH inhibition, analysis of the Pan-binding pocket has led to the development of two new structure-based motifs (the PAN and INTERFACE motifs). Our analyses also suggest that the type III PanK in the spore-forming B. anthracis plays an essential role in the novel thiol/disulfide redox biology of this category A biodefense pathogen. PMID:17323930

  15. The synthesis, structure, magnetic and luminescent properties of a new tetranuclear dysprosium (III) cluster

    SciTech Connect

    Chen, Yen-Han; Tsai, Yun-Fan; Lee, Gene-Hsian; Yang, En-Che

    2012-01-15

    The synthesis and characterization of [Dy{sub 4}(dhampH{sub 3}){sub 4}(NO{sub 3}){sub 2}](NO{sub 3}){sub 2} (1), a new tetranuclear dysprosium (III) complex, is described. The compound was characterized by its X-ray structure, magnetic properties as well as the luminescent spectra. The compound crystallizes in a P1-bar space group with a zig-zag linear form of geometry. The ac magnetic susceptibilities of the molecule indicate that it is a magnetic molecule with a slow magnetization relaxation. The molecule also exhibits an emission spectrum that was confirmed to be ligand based. These results indicate that this molecule has both a slow magnetization relaxation (that could be potentially a SMM) and luminescent properties. - Graphical Abstract: A new tetranuclear dysprosium (III) complex [Dy{sub 4}(dhampH{sub 3}){sub 4}(NO{sub 3}){sub 2}](NO{sub 3}){sub 2} is synthesized and reported in this paper. This molecule has luminescence and can potentially act as a SMM. Highlights: Black-Right-Pointing-Pointer A new designed ligand (dhampH{sub 5}) was syntheisized. Black-Right-Pointing-Pointer A new tetra-dysprosium cluster [Dy{sub 4}(dhampH{sub 3}){sub 4}(NO{sub 3}){sub 2}](NO{sub 3}){sub 2} was made. Black-Right-Pointing-Pointer Slow magnetization relaxation phenomenon was observed. Black-Right-Pointing-Pointer Ligand-based luminescence was observed.

  16. Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport

    SciTech Connect

    Tanaka, Masaaki; Ohya, Shinobu Nam Hai, Pham

    2014-03-15

    Spin-based electronics or spintronics is an emerging field, in which we try to utilize spin degrees of freedom as well as charge transport in materials and devices. While metal-based spin-devices, such as magnetic-field sensors and magnetoresistive random access memory using giant magnetoresistance and tunneling magnetoresistance, are already put to practical use, semiconductor-based spintronics has greater potential for expansion because of good compatibility with existing semiconductor technology. Many semiconductor-based spintronics devices with useful functionalities have been proposed and explored so far. To realize those devices and functionalities, we definitely need appropriate materials which have both the properties of semiconductors and ferromagnets. Ferromagnetic semiconductors (FMSs), which are alloy semiconductors containing magnetic atoms such as Mn and Fe, are one of the most promising classes of materials for this purpose and thus have been intensively studied for the past two decades. Here, we review the recent progress in the studies of the most prototypical III-V based FMS, p-type (GaMn)As and its heterostructures with focus on tunneling transport, Fermi level, and bandstructure. Furthermore, we cover the properties of a new n-type FMS, (In,Fe)As, which shows electron-induced ferromagnetism. These FMS materials having zinc-blende crystal structure show excellent compatibility with well-developed III-V heterostructures and devices.

  17. Remote online monitoring and measuring system for civil engineering structures

    NASA Astrophysics Data System (ADS)

    Kujawińska, Malgorzata; Sitnik, Robert; Dymny, Grzegorz; Karaszewski, Maciej; Michoński, Kuba; Krzesłowski, Jakub; Mularczyk, Krzysztof; Bolewicki, Paweł

    2009-06-01

    In this paper a distributed intelligent system for civil engineering structures on-line measurement, remote monitoring, and data archiving is presented. The system consists of a set of optical, full-field displacement sensors connected to a controlling server. The server conducts measurements according to a list of scheduled tasks and stores the primary data or initial results in a remote centralized database. Simultaneously the server performs checks, ordered by the operator, which may in turn result with an alert or a specific action. The structure of whole system is analyzed along with the discussion on possible fields of application and the ways to provide a relevant security during data transport. Finally, a working implementation consisting of a fringe projection, geometrical moiré, digital image correlation and grating interferometry sensors and Oracle XE database is presented. The results from database utilized for on-line monitoring of a threshold value of strain for an exemplary area of interest at the engineering structure are presented and discussed.

  18. Structural and Machine Design Using Piezoceramic Materials: A Guide for Structural Design Engineers

    NASA Technical Reports Server (NTRS)

    Inman, Daniel J.; Cudney, Harley H.

    2000-01-01

    Using piezoceramic materials is one way the design engineer can create structures which have an ability to both sense and respond to their environment. Piezoceramic materials can be used to create structural sensors and structural actuators. Because piezoceramic materials have transduction as a material property, their sensing or actuation functions are a result of what happens to the material. This is different than discrete devices we might attach to the structure. For example, attaching an accelerometer to a structure will yield an electrical signal proportional to the acceleration at the attachment point on the structure. Using a electromagnetic shaker as an actuator will create an applied force at the attachment point. Active material elements in a structural design are not easily modeled as providing transduction at a point, but rather they change the physics of the structure in the areas where they are used. Hence, a designer must not think of adding discrete devices to a structure to obtain an effect, but rather must design a structural system which accounts for the physical principles of all the elements in the structure. The purpose of this manual is to provide practicing engineers the information necessary to incorporate piezoelectric materials in structural design and machine design. First, we will review the solid-state physics of piezoelectric materials. Then we will discuss the physical characteristics of the electrical-active material-structural system. We will present the elements of this system which must be considered as part of the design task for a structural engineer. We will cover simple modeling techniques and review the features and capabilities of commercial design tools that are available. We will then cover practical how-to elements of working with piezoceramic materials. We will review sources of piezoceramic materials and built-up devices, and their characteristics. Finally, we will provide two design examples using piezoceramic

  19. Advanced stress analysis methods applicable to turbine engine structures

    NASA Technical Reports Server (NTRS)

    Pian, Theodore H. H.

    1991-01-01

    The following tasks on the study of advanced stress analysis methods applicable to turbine engine structures are described: (1) constructions of special elements which contain traction-free circular boundaries; (2) formulation of new version of mixed variational principles and new version of hybrid stress elements; (3) establishment of methods for suppression of kinematic deformation modes; (4) construction of semiLoof plate and shell elements by assumed stress hybrid method; and (5) elastic-plastic analysis by viscoplasticity theory using the mechanical subelement model.

  20. Overview of Lightweight Structures for Rotorcraft Engines and Drivetrains

    NASA Technical Reports Server (NTRS)

    Roberts, Gary D.

    2011-01-01

    This is an overview presentation of research being performed in the Advanced Materials Task within the NASA Subsonic Rotary Wing Project. This research is focused on technology areas that address both national goals and project goals for advanced rotorcraft. Specific technology areas discussed are: (1) high temperature materials for advanced turbines in turboshaft engines; (2) polymer matrix composites for lightweight drive system components; (3) lightweight structure approaches for noise and vibration control; and (4) an advanced metal alloy for lighter weight bearings and more reliable mechanical components. An overview of the technology in each area is discussed, and recent accomplishments are presented.

  1. Engineering band structure in nanoscale quantum-dot supercrystals.

    PubMed

    Baimuratov, Anvar S; Rukhlenko, Ivan D; Fedorov, Anatoly V

    2013-07-01

    Supercrystals made of periodically arranged semiconductor quantum dots (QDs) are promising structures for nanophotonics applications due to almost unlimited degrees of freedom enabling fine tuning of their optical responses. Here we demonstrate broad engineering opportunities associated with the possibility of tailoring the energy bands of excitons in two-dimensional quantum-dot supercrystals through the alteration in the QD arrangement. These opportunities offer an unprecedented control over the optical properties of the supercrystals, which may be used as a versatile material base for advanced photonics devices on the nanoscale.

  2. Novel DNA binding motifs in the DNA repair enzyme endonuclease III crystal structure.

    PubMed Central

    Thayer, M M; Ahern, H; Xing, D; Cunningham, R P; Tainer, J A

    1995-01-01

    The 1.85 A crystal structure of endonuclease III, combined with mutational analysis, suggests the structural basis for the DNA binding and catalytic activity of the enzyme. Helix-hairpin-helix (HhH) and [4Fe-4S] cluster loop (FCL) motifs, which we have named for their secondary structure, bracket the cleft separating the two alpha-helical domains of the enzyme. These two novel DNA binding motifs and the solvent-filled pocket in the cleft between them all lie within a positively charged and sequence-conserved surface region. Lys120 and Asp138, both shown by mutagenesis to be catalytically important, lie at the mouth of this pocket, suggesting that this pocket is part of the active site. The positions of the HhH motif and protruding FCL motif, which contains the DNA binding residue Lys191, can accommodate B-form DNA, with a flipped-out base bound within the active site pocket. The identification of HhH and FCL sequence patterns in other DNA binding proteins suggests that these motifs may be a recurrent structural theme for DNA binding proteins. Images PMID:7664751

  3. Crystal structure of new complexes of praseodymium(III) nitrate and ytterbium(III) nitrate with 2,2': 6,2''-terpyridine

    SciTech Connect

    Charushnikova, I. A. Auwer, C. Den

    2006-12-15

    The crystal structure of new complexes of praseodymium(III) and ytterbium(III) (elements from the initial and final parts of the lanthanide series), namely, [Pr(NO{sub 3}){sub 3} (Terpy)((CH{sub 3}){sub 2}CO)] (I) and [Yb(NO{sub 3}){sub 2}(Terpy)(H{sub 2}O){sub 2}]NO{sub 3} . 2H{sub 2}O (II), is investigated. The structure of compound I consists of [Pr(NO{sub 3}){sub 3}(Terpy)((CH{sub 3}){sub 2}CO)] neutral complexes. The coordination number of the praseodymium atom is 10. The coordination polyhedron of the praseodymium atom can be described as a distorted bicapped tetragonal antiprism. The structure of compound II is composed of [Yb(NO{sub 3}){sub 2}(Terpy)(H{sub 2}O){sub 2}]{sup +} cationic complexes, nitrate anions, and molecules of crystallization water. The structural components are joined together via a three-dimensional system of hydrogen bonds. The coordination polyhedron of the ytterbium atom can be represented as a distorted tricapped trigonal prism. The coordination number of the ytterbium atom is 9.

  4. Engineering NK Cells Modified With an EGFRvIII-specific Chimeric Antigen Receptor to Overexpress CXCR4 Improves Immunotherapy of CXCL12/SDF-1α-secreting Glioblastoma.

    PubMed

    Müller, Nadja; Michen, Susanne; Tietze, Stefanie; Töpfer, Katrin; Schulte, Alexander; Lamszus, Katrin; Schmitz, Marc; Schackert, Gabriele; Pastan, Ira; Temme, Achim

    2015-06-01

    Natural killer (NK) cells are promising effector cells for adjuvant immunotherapy of cancer. So far, several preclinical studies have shown the feasibility of gene-engineered NK cells, which upon expression of chimeric antigen receptors (CARs) are redirected to otherwise NK cell-resistant tumors. Yet, we reasoned that the efficiency of an immunotherapy using CAR-modified NK cells critically relies on efficient migration to the tumor site and might be improved by the engraftment of a receptor specific for a chemokine released by the tumor. On the basis of the DNAX-activation protein 12 (DAP12), a signaling adapter molecule involved in signal transduction of activating NK cell receptors, we constructed an epidermal growth factor variant III (EGFRvIII)-CAR, designated MR1.1-DAP12 which confers specific cytotoxicity of NK cell towards EGFRvIII glioblastoma cells in vitro and to established subcutaneous U87-MG tumor xenografts. So far, infusion of NK cells with expression of MR1.1-DAP12 caused a moderate but significantly delayed tumor growth and increased median survival time when compared with NK cells transduced with an ITAM-defective CAR. Notably, the further genetic engineering of these EGFRvIII-specific NK cells with the chemokine receptor CXCR4 conferred a specific chemotaxis to CXCL12/SDF-1α secreting U87-MG glioblastoma cells. Moreover, the administration of such NK cells resulted in complete tumor remission in a number of mice and a significantly increased survival when compared with the treatment of xenografts with NK cells expressing only the EGFRvIII-specific CAR or mock control. We conclude that chemokine receptor-engineered NK cells with concomitant expression of a tumor-specific CAR are a promising tool to improve adoptive tumor immunotherapy.

  5. Nebraska School Facilities: Educational Adequacy of Class III School District Structures

    ERIC Educational Resources Information Center

    Weidner, John M., Sr.

    2009-01-01

    In 2009, a replication of the Pool study was conducted. This study, however, focused on the school systems classified as Class III districts. Nebraska has 252 Class III districts. Compared with Class II (21), Class IV (1), and Class V(1) districts, the Class III districts offer a wide array of school settings, from urban to extremely rural, and…

  6. Crystal structure of tris-(ethyl-enedi-ammonium) hexasulfatopraseodymium(III) hexa-hydrate.

    PubMed

    Held, Peter

    2014-10-01

    In the title salt, (C2H10N2)3[Pr2(SO4)6]·6H2O, the Pr(III) cation is surrounded ninefold by five sulfate groups (two monodentate and three chelating) and by one water mol-ecule [range of Pr-O bond lengths 2.383 (3) to 2.582 (3) Å]. The [Pr(SO4)5(H2O)] groups are arranged in sheets parallel to (010). Two crystal water mol-ecules and two ethyl-enedi-ammonium cations (one with point group symmetry -1) connect the sheets via O-H⋯O and N-H⋯O hydrogen bonds from weak up to medium strength into a three-dimensional framework structure.

  7. Neutron structure of type-III antifreeze protein allows the reconstruction of AFP-ice interface.

    PubMed

    Howard, Eduardo I; Blakeley, Matthew P; Haertlein, Michael; Petit-Haertlein, Isabelle; Mitschler, Andre; Fisher, Stuart J; Cousido-Siah, Alexandra; Salvay, Andrés G; Popov, Alexandre; Muller-Dieckmann, Christoph; Petrova, Tatiana; Podjarny, Alberto

    2011-01-01

    Antifreeze proteins (AFPs) inhibit ice growth at sub-zero temperatures. The prototypical type-III AFPs have been extensively studied, notably by X-ray crystallography, solid-state and solution NMR, and mutagenesis, leading to the identification of a compound ice-binding surface (IBS) composed of two adjacent ice-binding sections, each which binds to particular lattice planes of ice crystals, poisoning their growth. This surface, including many hydrophobic and some hydrophilic residues, has been extensively used to model the interaction of AFP with ice. Experimentally observed water molecules facing the IBS have been used in an attempt to validate these models. However, these trials have been hindered by the limited capability of X-ray crystallography to reliably identify all water molecules of the hydration layer. Due to the strong diffraction signal from both the oxygen and deuterium atoms, neutron diffraction provides a more effective way to determine the water molecule positions (as D(2) O). Here we report the successful structure determination at 293 K of fully perdeuterated type-III AFP by joint X-ray and neutron diffraction providing a very detailed description of the protein and its solvent structure. X-ray data were collected to a resolution of 1.05 Å, and neutron Laue data to a resolution of 1.85 Å with a "radically small" crystal volume of 0.13 mm(3). The identification of a tetrahedral water cluster in nuclear scattering density maps has allowed the reconstruction of the IBS-bound ice crystal primary prismatic face. Analysis of the interactions between the IBS and the bound ice crystal primary prismatic face indicates the role of the hydrophobic residues, which are found to bind inside the holes of the ice surface, thus explaining the specificity of AFPs for ice versus water.

  8. CAR-Engineered NK Cells Targeting Wild-Type EGFR and EGFRvIII Enhance Killing of Glioblastoma and Patient-Derived Glioblastoma Stem Cells.

    PubMed

    Han, Jianfeng; Chu, Jianhong; Keung Chan, Wing; Zhang, Jianying; Wang, Youwei; Cohen, Justus B; Victor, Aaron; Meisen, Walter H; Kim, Sung-hak; Grandi, Paola; Wang, Qi-En; He, Xiaoming; Nakano, Ichiro; Chiocca, E Antonio; Glorioso, Joseph C; Kaur, Balveen; Caligiuri, Michael A; Yu, Jianhua

    2015-07-09

    Glioblastoma (GB) remains the most aggressive primary brain malignancy. Adoptive transfer of chimeric antigen receptor (CAR)-modified immune cells has emerged as a promising anti-cancer approach, yet the potential utility of CAR-engineered natural killer (NK) cells to treat GB has not been explored. Tumors from approximately 50% of GB patients express wild-type EGFR (wtEGFR) and in fewer cases express both wtEGFR and the mutant form EGFRvIII; however, previously reported CAR T cell studies only focus on targeting EGFRvIII. Here we explore whether both wtEGFR and EGFRvIII can be effectively targeted by CAR-redirected NK cells to treat GB. We transduced human NK cell lines NK-92 and NKL, and primary NK cells with a lentiviral construct harboring a second generation CAR targeting both wtEGFR and EGFRvIII and evaluated the anti-GB efficacy of EGFR-CAR-modified NK cells. EGFR-CAR-engineered NK cells displayed enhanced cytolytic capability and IFN-γ production when co-cultured with GB cells or patient-derived GB stem cells in an EGFR-dependent manner. In two orthotopic GB xenograft mouse models, intracranial administration of NK-92-EGFR-CAR cells resulted in efficient suppression of tumor growth and significantly prolonged the tumor-bearing mice survival. These findings support intracranial administration of NK-92-EGFR-CAR cells represents a promising clinical strategy to treat GB.

  9. New Insights into Structure and Luminescence of EuIII and SmIII Complexes of the 3,4,3-LI(1,2-HOPO) Ligand

    PubMed Central

    2016-01-01

    We report the preparation and new insight into photophysical properties of luminescent hydroxypyridonate complexes [MIIIL]− (M = Eu or Sm) of the versatile 3,4,3-LI(1,2-HOPO) ligand (L). We report the crystal structure of this ligand with EuIII as well as insights into the coordination behavior and geometry in solution by using magnetic circular dichroism. In addition TD-DFT calculations were used to examine the excited states of the two different chromophores present in the 3,4,3-LI(1,2-HOPO) ligand. We find that the EuIII and SmIII complexes of this ligand undergo a transformation after in situ preparation to yield complexes with higher quantum yield (QY) over time. It is proposed that the lower QY in the in situ complexes is not only due to water quenching but could also be due to a lower degree of f-orbital overlap (in a kinetic isomer) as indicated by magnetic circular dichroism measurements. PMID:25607882

  10. Assessment and economic analysis of the MOD III Stirling-engine driven chiller system. Final report, October 1989-July 1990

    SciTech Connect

    Moryl, J.

    1990-07-01

    The Stirling engine is an inherently clean and efficient engine. With the requirements for environmentally benign emissions and high energy efficiency, the Stirling engine is an attractive alternative to both internal combustion (IC) engines and electric motors. The study evaluated a Stirling-engine-driven chiller package. Technically, the Stirling engine is a good selection as a compressor drive, with inherently low vibrations, quiet operation, long life, and low maintenance. Exhaust emissions are below the projected 1995 stringent California standards. Economically, the Stirling-engine-driven chiller is a viable alternative to both IV-engine and electric-driven chillers, trading off slightly higher installed cost against lower total operating expenses. The penetration of a small portion of the projected near-term stationary engine market opportunity will provide the volume production basis to achieve competitively priced engines.

  11. Advanced fabrication techniques for hydrogen-cooled engine structures

    NASA Technical Reports Server (NTRS)

    Buchmann, O. A.; Arefian, V. V.; Warren, H. A.; Vuigner, A. A.; Pohlman, M. J.

    1985-01-01

    Described is a program for development of coolant passage geometries, material systems, and joining processes that will produce long-life hydrogen-cooled structures for scramjet applications. Tests were performed to establish basic material properties, and samples constructed and evaluated to substantiate fabrication processes and inspection techniques. Results of the study show that the basic goal of increasing the life of hydrogen-cooled structures two orders of magnitude relative to that of the Hypersonic Research Engine can be reached with available means. Estimated life is 19000 cycles for the channels and 16000 cycles for pin-fin coolant passage configurations using Nickel 201. Additional research is required to establish the fatigue characteristics of dissimilar-metal coolant passages (Nickel 201/Inconel 718) and to investigate the embrittling effects of the hydrogen coolant.

  12. Biochemical and Structural Characterization of Germicidin Synthase: Analysis of a Type III Polyketide Synthase That Employs Acyl-ACP as a Starter Unit Donor

    SciTech Connect

    Chemler, Joseph A.; Buchholz, Tonia J.; Geders, Todd W.; Akey, David L.; Rath, Christopher M.; Chlipala, George E.; Smith, Janet L.; Sherman, David H.

    2012-08-10

    Germicidin synthase (Gcs) from Streptomyces coelicolor is a type III polyketide synthase (PKS) with broad substrate flexibility for acyl groups linked through a thioester bond to either coenzyme A (CoA) or acyl carrier protein (ACP). Germicidin synthesis was reconstituted in vitro by coupling Gcs with fatty acid biosynthesis. Since Gcs has broad substrate flexibility, we directly compared the kinetic properties of Gcs with both acyl-ACP and acyl-CoA. The catalytic efficiency of Gcs for acyl-ACP was 10-fold higher than for acyl-CoA, suggesting a strong preference toward carrier protein starter unit transfer. The 2.9 {angstrom} germicidin synthase crystal structure revealed canonical type III PKS architecture along with an unusual helical bundle of unknown function that appears to extend the dimerization interface. A pair of arginine residues adjacent to the active site affect catalytic activity but not ACP binding. This investigation provides new and surprising information about the interactions between type III PKSs and ACPs that will facilitate the construction of engineered systems for production of novel polyketides.

  13. Cabin fuselage structural design with engine installation and control system

    NASA Technical Reports Server (NTRS)

    Balakrishnan, Tanapaal; Bishop, Mike; Gumus, Ilker; Gussy, Joel; Triggs, Mike

    1994-01-01

    Design requirements for the cabin, cabin system, flight controls, engine installation, and wing-fuselage interface that provide adequate interior volume for occupant seating, cabin ingress and egress, and safety are presented. The fuselage structure must be sufficient to meet the loadings specified in the appropriate sections of Federal Aviation Regulation Part 23. The critical structure must provide a safe life of 10(exp 6) load cycles and 10,000 operational mission cycles. The cabin seating and controls must provide adjustment to account for various pilot physiques and to aid in maintenance and operation of the aircraft. Seats and doors shall not bind or lockup under normal operation. Cabin systems such as heating and ventilation, electrical, lighting, intercom, and avionics must be included in the design. The control system will consist of ailerons, elevator, and rudders. The system must provide required deflections with a combination of push rods, bell cranks, pulleys, and linkages. The system will be free from slack and provide smooth operation without binding. Environmental considerations include variations in temperature and atmospheric pressure, protection against sand, dust, rain, humidity, ice, snow, salt/fog atmosphere, wind and gusts, and shock and vibration. The following design goals were set to meet the requirements of the statement of work: safety, performance, manufacturing and cost. To prevent the engine from penetrating the passenger area in the event of a crash was the primary safety concern. Weight and the fuselage aerodynamics were the primary performance concerns. Commonality and ease of manufacturing were major considerations to reduce cost.

  14. Engineering structured light with Vogel spiral arrays of nanoparticles

    NASA Astrophysics Data System (ADS)

    Lawrence, Nate; Trevino, Jacob; Dal Negro, Luca

    2013-03-01

    We present a general analytical model for light scattering by arbitrary Vogel spiral arrays of circular apertures uniformly illuminated at normal incidence. This model suffices to unveil the fundamental mathematical structure of their complex Fraunhofer diffraction patterns and enables the engineering of optical beams carrying multiple values of orbital angular momentum (OAM). By performing analytical Fourier-Hankel decomposition of spiral arrays and far field patterns, we rigorously demonstrate the ability to encode specific numerical sequences onto the OAM values of diffracted optical beams. In particular, we show that these OAM values are determined by the rational approximations of the continued fraction expansions of the irrational angles utilized to generate Vogel spirals. Finally, we experimentally demonstrate structured light carrying multiple values of OAM in the far-field scattering region of Vogel spiral arrays of metallic nanoparticles. Using Fourier-Hankel mode decomposition analysis and interferometric reconstruction of the complex amplitude of scattered waves, we show the ability to encode well-defined numerical sequences, determined by the aperiodic spiral geometry, into azimuthal OAM values, in excellent agreement with analytical scattering theory. The generation of sequences of OAM values by light scattering from engineered aperiodic surfaces is relevant to a number of device applications for secure optical communication, classical and quantum cryptography.

  15. Fatty acid biosynthesis revisited: Structure elucidation and metabolic engineering

    DOE PAGES

    Beld, Joris; Lee, D. John; Burkart, Michael D.

    2014-10-20

    Fatty acids are primary metabolites synthesized by complex, elegant, and essential biosynthetic machinery. Fatty acid synthases resemble an iterative assembly line, with an acyl carrier protein conveying the growing fatty acid to necessary enzymatic domains for modification. Each catalytic domain is a unique enzyme spanning a wide range of folds and structures. Although they harbor the same enzymatic activities, two different types of fatty acid synthase architectures are observed in nature. During recent years, strained petroleum supplies have driven interest in engineering organisms to either produce more fatty acids or specific high value products. Such efforts require a fundamental understandingmore » of the enzymatic activities and regulation of fatty acid synthases. Despite more than one hundred years of research, we continue to learn new lessons about fatty acid synthases' many intricate structural and regulatory elements. Lastly, in this review, we summarize each enzymatic domain and discuss efforts to engineer fatty acid synthases, providing some clues to important challenges and opportunities in the field.« less

  16. Glucoamylase: structure/function relationships, and protein engineering.

    PubMed

    Sauer, J; Sigurskjold, B W; Christensen, U; Frandsen, T P; Mirgorodskaya, E; Harrison, M; Roepstorff, P; Svensson, B

    2000-12-29

    Glucoamylases are inverting exo-acting starch hydrolases releasing beta-glucose from the non-reducing ends of starch and related substrates. The majority of glucoamylases are multidomain enzymes consisting of a catalytic domain connected to a starch-binding domain by an O-glycosylated linker region. Three-dimensional structures have been determined of free and inhibitor complexed glucoamylases from Aspergillus awamori var. X100, Aspergillus niger, and Saccharomycopsis fibuligera. The catalytic domain folds as a twisted (alpha/alpha)(6)-barrel with a central funnel-shaped active site, while the starch-binding domain folds as an antiparallel beta-barrel and has two binding sites for starch or beta-cyclodextrin. Certain glucoamylases are widely applied industrially in the manufacture of glucose and fructose syrups. For more than a decade mutational investigations of glucoamylase have addressed fundamental structure/function relationships in the binding and catalytic mechanisms. In parallel, issues of relevance for application have been pursued using protein engineering to improve the industrial properties. The present review focuses on recent findings on the catalytic site, mechanism of action, substrate recognition, the linker region, the multidomain architecture, the engineering of specificity and stability, and roles of individual substrate binding subsites.

  17. Recent Advances In Optimization Of Aerospace Structures And Engines

    NASA Astrophysics Data System (ADS)

    Rao*, J. S.

    Optimization theories have been well advanced during the last few decades; however when it came to handle real life engineering structures it has been always time consuming and approximate when the structure geometry is highly complex. Design of Experiments has helped in understanding the influence of size and shape parameters on achieving a specified objective function with required constraints and a suitable analysis platform, but has its limitations in arriving at the final optimal solution. There are several commercial codes that addressed this need to handle large size structures subjected to dynamic loads. Most advanced tools in this category are Altair OptiStruct and Altair HyperStudy available in Altair HyperWorks suite. Application of these tools in achieving optimum solutions for linear advanced aircraft structures for minimization of weight are first explained. The application of these tools for globally elastic and locally plastic nonlinear structures to reduce local plastic strains and achieve higher life under dynamic loads will then be discussed.

  18. Structural, Hirshfeld surface and spectroscopic studies of the noncentrosymmetric 1-ethylpiperazinediium pentachloroantimonate (III) monohydrate

    NASA Astrophysics Data System (ADS)

    Soudani, S.; Zeller, M.; Jelsch, C.; Lefebvre, F.; Ben Nasr, Cherif

    2016-08-01

    1-Ethylpiperazinediium pentachloroantimonate (III) monohydrate, C6H16N2SbCl5·H2O, has been synthesized by the reaction of antimony trioxide (Sb2O3) and 1-ethylpiperazine in an aqueous solution of hydrochloric acid. The structure crystallizes in orthorhombic system, in the non-centrosymmetric space group Pca21 and consists of isolated [C6H16N2]2+ cations, square pyramidal [SbCl5]2- anions and lattice water molecules. Osbnd H⋯Cl hydrogen bonds link the [SbCl5]2- anions and water molecules to form double chains stretching along the [101] direction. The chains in turn are linked to the organic cations via Nsbnd H⋯Cl, Csbnd H⋯Cl, Csbnd H⋯O and Nsbnd H⋯O hydrogen bonds to form a three-dimensional network. This structure presents an example of a general square pyramidal complex ion containing a stereo-chemically active lone pair of electrons. Solid state 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure, and vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the NMR peaks and IR absorption bands. The interactions variability of the two independent cations and ten chloride atoms is analyzed via Hirshfeld surface analysis.

  19. Structure of a bacterial type III secretion system in contact with a host membrane in situ

    NASA Astrophysics Data System (ADS)

    Nans, Andrea; Kudryashev, Mikhail; Saibil, Helen R.; Hayward, Richard D.

    2015-12-01

    Many bacterial pathogens of animals and plants use a conserved type III secretion system (T3SS) to inject virulence effector proteins directly into eukaryotic cells to subvert host functions. Contact with host membranes is critical for T3SS activation, yet little is known about T3SS architecture in this state or the conformational changes that drive effector translocation. Here we use cryo-electron tomography and sub-tomogram averaging to derive the intact structure of the primordial Chlamydia trachomatis T3SS in the presence and absence of host membrane contact. Comparison of the averaged structures demonstrates a marked compaction of the basal body (4 nm) occurs when the needle tip contacts the host cell membrane. This compaction is coupled to a stabilization of the cytosolic sorting platform-ATPase. Our findings reveal the first structure of a bacterial T3SS from a major human pathogen engaged with a eukaryotic host, and reveal striking `pump-action' conformational changes that underpin effector injection.

  20. Magnetic Structures of Heterometallic M(II)-M(III) Formate Compounds.

    PubMed

    Mazzuca, Lidia; Cañadillas-Delgado, Laura; Rodríguez-Velamazán, J Alberto; Fabelo, Oscar; Scarrozza, Marco; Stroppa, Alessandro; Picozzi, Silvia; Zhao, Jiong-Peng; Bu, Xian-He; Rodríguez-Carvajal, Juan

    2017-01-03

    A study of the magnetic structure of the [NH2(CH3)2]n[Fe(III)M(II)(HCOO)6]n niccolite-like compounds, with M(II) = Co(II) (2) and Mn(II) (3) ions, has been carried out using neutron diffraction and compared with the previously reported Fe(II)-containing compound (1). The inclusion of two different metallic atoms into the niccolite-like structure framework leads to the formation of isostructural compounds with very different magnetic behaviors due to the compensation or not of the different spins involved in each lattice. Below TN, the magnetic order in these compounds varies from ferrimagnetic behavior for 1 and 2 to an antiferromagnetic behavior with a weak spin canting for 3. Structure refinements of 2 and 3 at low temperature (45 K) have been carried out combining synchrotron X-ray and high-resolution neutron diffraction in a multipattern approach. The magnetic structures have been determined from the difference patterns between the neutron data in the paramagnetic and the magnetically ordered regions. These difference patterns have been analyzed using a simulated annealing protocol and symmetry analysis techniques. The obtained magnetic structures have been further rationalized by means of ab initio DFT calculations. The direction of the magnetic moment of each compound has been determined. The easy axis of the M(II) for compound 1 (Fe(II)) is along the c axis; for compound 2 (Co(II)), the moments are mainly within the ab plane; finally, for compound 3 (Mn(II)), the calculations show that the moments have components both in the ab plane and along the c axis.

  1. βIII Spectrin Regulates the Structural Integrity and the Secretory Protein Transport of the Golgi Complex*

    PubMed Central

    Salcedo-Sicilia, Laia; Granell, Susana; Jovic, Marko; Sicart, Adrià; Mato, Eugenia; Johannes, Ludger; Balla, Tamas; Egea, Gustavo

    2013-01-01

    A spectrin-based cytoskeleton is associated with endomembranes, including the Golgi complex and cytoplasmic vesicles, but its role remains poorly understood. Using new generated antibodies to specific peptide sequences of the human βIII spectrin, we here show its distribution in the Golgi complex, where it is enriched in the trans-Golgi and trans-Golgi network. The use of a drug-inducible enzymatic assay that depletes the Golgi-associated pool of PI4P as well as the expression of PH domains of Golgi proteins that specifically recognize this phosphoinositide both displaced βIII spectrin from the Golgi. However, the interference with actin dynamics using actin toxins did not affect the localization of βIII spectrin to Golgi membranes. Depletion of βIII spectrin using siRNA technology and the microinjection of anti-βIII spectrin antibodies into the cytoplasm lead to the fragmentation of the Golgi. At ultrastructural level, Golgi fragments showed swollen distal Golgi cisternae and vesicular structures. Using a variety of protein transport assays, we show that the endoplasmic reticulum-to-Golgi and post-Golgi protein transports were impaired in βIII spectrin-depleted cells. However, the internalization of the Shiga toxin subunit B to the endoplasmic reticulum was unaffected. We state that βIII spectrin constitutes a major skeletal component of distal Golgi compartments, where it is necessary to maintain its structural integrity and secretory activity, and unlike actin, PI4P appears to be highly relevant for the association of βIII spectrin the Golgi complex. PMID:23233669

  2. Structural engineering masters level education framework of knowledge for the needs of initial professional practice

    NASA Astrophysics Data System (ADS)

    Balogh, Zsuzsa Enriko

    For at least the last decade, engineering, civil engineering, along with structural engineering as a profession within civil engineering, have and continue to face an emerging need for "Raising the Bar" of preparedness of young engineers seeking to become practicing professional engineers. The present consensus of the civil engineering profession is that the increasing need for broad and in-depth knowledge should require the young structural engineers to have at least a Masters-Level education. This study focuses on the Masters-Level preparedness in the structural engineering area within the civil engineering field. It follows much of the methodology used in the American Society of Civil Engineers (ASCE) Body of Knowledge determination for civil engineering and extends this type of study to better define the portion of the young engineers preparation beyond the undergraduate program for one specialty area of civil engineering. The objective of this research was to create a Framework of Knowledge for the young engineer which identifies and recognizes the needs of the profession, along with the profession's expectations of how those needs can be achieved in the graduate-level academic setting, in the practice environment, and through lifelong learning opportunities with an emphasis on the initial five years experience past completion of a Masters program in structural engineering. This study applied a modified Delphi method to obtain the critical information from members of the structural engineering profession. The results provide a Framework of Knowledge which will be useful to several groups seeking to better ensure the preparedness of the future young structural engineers at the Masters-Level.

  3. Probabilistic structural analysis methods for improving Space Shuttle engine reliability

    NASA Technical Reports Server (NTRS)

    Boyce, L.

    1989-01-01

    Probabilistic structural analysis methods are particularly useful in the design and analysis of critical structural components and systems that operate in very severe and uncertain environments. These methods have recently found application in space propulsion systems to improve the structural reliability of Space Shuttle Main Engine (SSME) components. A computer program, NESSUS, based on a deterministic finite-element program and a method of probabilistic analysis (fast probability integration) provides probabilistic structural analysis for selected SSME components. While computationally efficient, it considers both correlated and nonnormal random variables as well as an implicit functional relationship between independent and dependent variables. The program is used to determine the response of a nickel-based superalloy SSME turbopump blade. Results include blade tip displacement statistics due to the variability in blade thickness, modulus of elasticity, Poisson's ratio or density. Modulus of elasticity significantly contributed to blade tip variability while Poisson's ratio did not. Thus, a rational method for choosing parameters to be modeled as random is provided.

  4. Engineering robust and tunable spatial structures with synthetic gene circuits.

    PubMed

    Kong, Wentao; Blanchard, Andrew E; Liao, Chen; Lu, Ting

    2017-01-25

    Controllable spatial patterning is a major goal for the engineering of biological systems. Recently, synthetic gene circuits have become promising tools to achieve the goal; however, they need to possess both functional robustness and tunability in order to facilitate future applications. Here we show that, by harnessing the dual signaling and antibiotic features of nisin, simple synthetic circuits can direct Lactococcus lactis populations to form programmed spatial band-pass structures that do not require fine-tuning and are robust against environmental and cellular context perturbations. Although robust, the patterns are highly tunable, with their band widths specified by the external nisin gradient and cellular nisin immunity. Additionally, the circuits can direct cells to consistently generate designed patterns, even when the gradient is driven by structured nisin-producing bacteria and the patterning cells are composed of multiple species. A mathematical model successfully reproduces all of the observed patterns. Furthermore, the circuits allow us to establish predictable structures of synthetic communities and controllable arrays of cellular stripes and spots in space. This study offers new synthetic biology tools to program spatial structures. It also demonstrates that a deep mining of natural functionalities of living systems is a valuable route to build circuit robustness and tunability.

  5. Engineering robust and tunable spatial structures with synthetic gene circuits

    PubMed Central

    Kong, Wentao; Blanchard, Andrew E.; Liao, Chen; Lu, Ting

    2017-01-01

    Controllable spatial patterning is a major goal for the engineering of biological systems. Recently, synthetic gene circuits have become promising tools to achieve the goal; however, they need to possess both functional robustness and tunability in order to facilitate future applications. Here we show that, by harnessing the dual signaling and antibiotic features of nisin, simple synthetic circuits can direct Lactococcus lactis populations to form programmed spatial band-pass structures that do not require fine-tuning and are robust against environmental and cellular context perturbations. Although robust, the patterns are highly tunable, with their band widths specified by the external nisin gradient and cellular nisin immunity. Additionally, the circuits can direct cells to consistently generate designed patterns, even when the gradient is driven by structured nisin-producing bacteria and the patterning cells are composed of multiple species. A mathematical model successfully reproduces all of the observed patterns. Furthermore, the circuits allow us to establish predictable structures of synthetic communities and controllable arrays of cellular stripes and spots in space. This study offers new synthetic biology tools to program spatial structures. It also demonstrates that a deep mining of natural functionalities of living systems is a valuable route to build circuit robustness and tunability. PMID:27899571

  6. Acoustic-Structure Interaction in Rocket Engines: Validation Testing

    NASA Technical Reports Server (NTRS)

    Davis, R. Benjamin; Joji, Scott S.; Parks, Russel A.; Brown, Andrew M.

    2009-01-01

    While analyzing a rocket engine component, it is often necessary to account for any effects that adjacent fluids (e.g., liquid fuels or oxidizers) might have on the structural dynamics of the component. To better characterize the fully coupled fluid-structure system responses, an analytical approach that models the system as a coupled expansion of rigid wall acoustic modes and in vacuo structural modes has been proposed. The present work seeks to experimentally validate this approach. To experimentally observe well-coupled system modes, the test article and fluid cavities are designed such that the uncoupled structural frequencies are comparable to the uncoupled acoustic frequencies. The test measures the natural frequencies, mode shapes, and forced response of cylindrical test articles in contact with fluid-filled cylindrical and/or annular cavities. The test article is excited with a stinger and the fluid-loaded response is acquired using a laser-doppler vibrometer. The experimentally determined fluid-loaded natural frequencies are compared directly to the results of the analytical model. Due to the geometric configuration of the test article, the analytical model is found to be valid for natural modes with circumferential wave numbers greater than four. In the case of these modes, the natural frequencies predicted by the analytical model demonstrate excellent agreement with the experimentally determined natural frequencies.

  7. Structural Analysis of a Specialized Type III Secretion System Peptidoglycan-cleaving Enzyme*

    PubMed Central

    Burkinshaw, Brianne J.; Deng, Wanyin; Lameignère, Emilie; Wasney, Gregory A.; Zhu, Haizhong; Worrall, Liam J.; Finlay, B. Brett; Strynadka, Natalie C.J.

    2015-01-01

    The Gram-negative bacterium enteropathogenic Escherichia coli uses a syringe-like type III secretion system (T3SS) to inject virulence or “effector” proteins into the cytoplasm of host intestinal epithelial cells. To assemble, the T3SS must traverse both bacterial membranes, as well as the peptidoglycan layer. Peptidoglycan is made of repeating N-acetylmuramic acid and N-acetylglucosamine disaccharides cross-linked by pentapeptides to form a tight mesh barrier. Assembly of many macromolecular machines requires a dedicated peptidoglycan lytic enzyme (PG-lytic enzyme) to locally clear peptidoglycan. Here we have solved the first structure of a T3SS-associated PG-lytic enzyme, EtgA from enteropathogenic E. coli. Unexpectedly, the active site of EtgA has features in common with both lytic transglycosylases and hen egg white lysozyme. Most notably, the β-hairpin region resembles that of lysozyme and contains an aspartate that aligns with lysozyme Asp-52 (a residue critical for catalysis), a conservation not observed in other previously characterized lytic transglycosylase families to which the conserved T3SS enzymes had been presumed to belong. Mutation of the EtgA catalytic glutamate, Glu-42, conserved across lytic transglycosylases and hen egg white lysozyme, and this differentiating aspartate diminishes type III secretion in vivo, supporting its essential role in clearing the peptidoglycan for T3SS assembly. Finally, we show that EtgA forms a 1:1 complex with the building block of the polymerized T3SS inner rod component, EscI, and that this interaction enhances PG-lytic activity of EtgA in vitro, collectively providing the necessary strict localization and regulation of the lytic activity to prevent overall cell lysis. PMID:25678709

  8. Synthesis, crystal structures, and properties of oxovanadium(IV)-lanthanide(III) heteronuclear complexes.

    PubMed

    Shi, Wei; Chen, Xiao-Yan; Zhao, Yan-Nan; Zhao, Bin; Cheng, Peng; Yu, Ao; Song, Hai-Bin; Wang, Hong-Gen; Liao, Dai-Zheng; Yan, Shi-Ping; Jiang, Zong-Hui

    2005-08-19

    A new series of oxovanadium(IV)-lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)](3)21 H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)} 8.5 H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)}8.5 H2O (3), {[Eu(H2O)7][(VO)2(TTHA)](1.5)} 10.5 H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H(6)TTHA as structure-directing agent. X-ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2- unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2- ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2- ion. Compound 4 is an extended one-dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2- ions. For 5, the structure is further assembled into a three-dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV)-lanthanide(III) coordination polymers and thus enlarge the realm of 3d-4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions.

  9. Tuning intracellular homeostasis of human uroporphyrinogen III synthase by enzyme engineering at a single hotspot of congenital erythropoietic porphyria.

    PubMed

    ben Bdira, Fredj; González, Esperanza; Pluta, Paula; Laín, Ana; Sanz-Parra, Arantza; Falcon-Perez, Juan Manuel; Millet, Oscar

    2014-11-01

    Congenital erythropoietic porphyria (CEP) results from a deficiency in uroporphyrinogen III synthase enzyme (UROIIIS) activity that ultimately stems from deleterious mutations in the uroS gene. C73 is a hotspot for these mutations and a C73R substitution, which drastically reduces the enzyme activity and stability, is found in almost one-third of all reported CEP cases. Here, we have studied the structural basis, by which mutations in this hotspot lead to UROIIIS destabilization. First, a strong interdependency is observed between the volume of the side chain at position 73 and the folded protein. Moreover, there is a correlation between the in vitro half-life of the mutated proteins and their expression levels in eukaryotic cell lines. Molecular modelling was used to rationalize the results, showing that the mutation site is coupled to the hinge region separating the two domains. Namely, mutations at position 73 modulate the inter-domain closure and ultimately affect protein stability. By incorporating residues capable of interacting with R73 to stabilize the hinge region, catalytic activity was fully restored and a moderate increase in the kinetic stability of the enzyme was observed. These results provide an unprecedented rationale for a destabilizing missense mutation and pave the way for the effective design of molecular chaperones as a therapy against CEP.

  10. Solution thermodynamics and structures of biscatecholamide complexes of Fe(III) and U(VI)

    SciTech Connect

    Gohdes, J.W.; Reilly, S.D.; Pecha, A.W.; Neu, M.P.

    1996-12-31

    We have studied the solution and solid-state complexes of a bis-catecholamide ligand, 2-LICAMS, with Fe(III) and U(VI). The first protonation constant was found to be pK{sub al} = 14.2(3) using {sup 1}H NMR titrations. Subsequent protonation constants were determined by potentiometric titration in 0.1 M TMAOTf at 25{degrees}C to be pK{sub a2} = 11.2(1), pK{sub 13} =6.5(1), pK{sub a4}= 5.9(1). Ligand-metal formation constants, {Beta}{sub mlh}, were found to be log {beta}{sub 110} = 31.4(2), log {beta}{sub 111} = 31.7(2), log {beta}{sub 112} = 34.9(2), and log {beta}11.1 = 18.0(1) for uranium(VI). To discriminate between monomeric or dimeric species models which both fit the potentiometric titration data, we isolated the hydroxide species and determined its single-crystal X-ray structure and EXAFS. The structure consists of a dimeric, bis-hydroxide bridged iron core which is spanned by two ligands. This study of solution equilibria indicates a higher stability for iron complexes of 2-LICAMS relative to uranyl complexes.

  11. Blue light emission from cyclometallated iridium (III) cyano complexes: Syntheses, crystal structures, and photophysical properties

    DOE PAGES

    Sanner, Robert D.; Cherepy, Nerine J.; Young, Jr., Victor G.

    2015-11-02

    In this study, we describe the synthesis and crystal structures of four iridium compounds containing the 2-(4,6-difluorophenyl)pyridyl ligand. Cleavage of dichloro-bridged iridium(III) dimers with phosphorus ligands leads to (46dfppy)2Ir(L)(Cl) where L = PPh3 or P(OPh)3. Treatment of the chloro compounds with cyanide forms the cyano complexes (46dfppy)2Ir(L)(CN). All complexes exhibit a trans effect in their molecular structures due to the phosphorus ligands, with the phosphite having a greater effect than the phosphine. With L = PPh3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.24), quantum yield of 0.66 ± 0.15 and 4.5 ± 0.5 μs decay timemore » is measured. For L = P(OPh)3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.21), quantum yield of 0.65 ± 0.15 and 2.9 ± 0.3 μs decay time is measured.« less

  12. Blue light emission from cyclometallated iridium (III) cyano complexes: Syntheses, crystal structures, and photophysical properties

    SciTech Connect

    Sanner, Robert D.; Cherepy, Nerine J.; Young, Jr., Victor G.

    2015-11-02

    In this study, we describe the synthesis and crystal structures of four iridium compounds containing the 2-(4,6-difluorophenyl)pyridyl ligand. Cleavage of dichloro-bridged iridium(III) dimers with phosphorus ligands leads to (46dfppy)2Ir(L)(Cl) where L = PPh3 or P(OPh)3. Treatment of the chloro compounds with cyanide forms the cyano complexes (46dfppy)2Ir(L)(CN). All complexes exhibit a trans effect in their molecular structures due to the phosphorus ligands, with the phosphite having a greater effect than the phosphine. With L = PPh3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.24), quantum yield of 0.66 ± 0.15 and 4.5 ± 0.5 μs decay time is measured. For L = P(OPh)3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.21), quantum yield of 0.65 ± 0.15 and 2.9 ± 0.3 μs decay time is measured.

  13. Structure-property relations in engineered semiconductor nanomaterials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hollingsworth, Jennifer A.; Htoon, Han

    2016-09-01

    Particle-size or `quantum-confinement' effects have been used for decades to tune semiconductor opto-electronic properties. More recently, particle size control as the primary means for properties control has been succeeded by nanoscale hetero-structuring. In this case, the nanosized particle is modified to include internal, nanoscale interfaces, generally defined by compositional variations that induce additional changes to semiconductor properties. These changes can entail enhancements to the size-induced properties as well as unexpected or `emergent' behaviors. Common structural motifs include enveloping a spherical semiconductor nanocrystal, i.e., a quantum dot, within a shell of a different composition. In this talk, I will discuss how solution-phase synthesis can be used to create these structures with precisely `engineered' complexity. Most notably, I will review our experiences with so-called `giant' quantum dots that, due to their internal nanoscale structure, exhibit a range of novel behaviors, including being non-blinking and non-photobleaching (Chen et al. J. Am. Chem. Soc. 2008, 130, 5026; Ghosh et al. J. Am. Chem. Soc. 2012, 134, 9634; Dennis et al. Nano Lett. 2012 12, 5545; Acharya et al. J. Am. Chem. Soc. 2015, 137, 3755), and remarkably efficient emitters of `multi-excitons' due to extreme suppression of Auger recombination (Mangum et al. Nanoscale 2014, 6, 3712; Gao et al. Adv. Optical Mater. 2015, 3, 39). I will discuss recent work extending non-blinking behavior to the blue/green and "dual-color" emission, and show how correlated optical/structural characterization can reveal new information regarding structure-property relations to guide new nanomaterials development (Orfield et al. ACS Nano, Article ASAP).

  14. MoSi2-Base Structural Composite Passed Engine Test

    NASA Technical Reports Server (NTRS)

    Nathal, Michael V.; Hebsur, Mohan G.

    1999-01-01

    The intermetallic compound molybdenum disilicide (MoSi2) is an attractive high-temperature structural material for advanced engine applications. It has excellent oxidation resistance, a high melting point, relatively low density, and high thermal conductivity; and it is easily machined. Past research at the NASA Lewis Research Center has resulted in the development of a hybrid composite consisting of a MoSi2 matrix reinforced with silicon nitride (Si3N4) particulate and silicon carbide (SiC) fibers. This composite has demonstrated attractive strength, toughness, thermal fatigue, and oxidation resistance, including resistance to "pest" oxidation. These properties attracted the interest of the Office of Naval Research and Pratt & Whitney, and a joint NASA/Navy/Pratt & Whitney effort was developed to continue to mature the MoSi2 composite technology. A turbine blade outer air seal, which was part of the Integrated High Performance Turbine Engine Technology (IHPTET) program, was chosen as a first component on which to focus.

  15. Cylinder head structure for V-type engine

    SciTech Connect

    Okada, M.; Asanomi, K.; Choshi, M.; Abe, R.

    1988-03-08

    A cylinder head structure for a V-type engine having a pair of cylinder banks is described comprising a pair of cylinder head members which are the same in shape and oriented in opposite directions and which are provided in each of the front and rear end wall portions with an opening, and camshaft supported for rotation in the respective cylinder head members so that the respective one ends of the camshafts project outside through the openings on the same end of the engine. A cam pulley is mounted on the projecting portion of each cam shaft, a transmission belt means is for transmitting the driving force off the crankshaft to the cam pulley on each camshaft, a pair of first cover members are mounted on the end wall portions of the respective cylinder head members through which the camshafts project to form closed cross section spaces together with the corresponding cylinder head members for covering the transmission belt means, and second cover members are mounted on the end wall portions of the respective cylinder heads opposite to the end wall portions through which the camshafts project to cover the openings therein.

  16. Unmasking Snake Venom of Bothrops leucurus: Purification and Pharmacological and Structural Characterization of New PLA2 Bleu TX-III

    PubMed Central

    Marangoni, Fábio André; Ponce-Soto, Luis Alberto; Marangoni, Sergio; Landucci, Elen Cristina Teizem

    2013-01-01

    Bleu TX-III was isolated from Bothrops leucurus snake venom on one-step analytical chromatography reverse phase HPLC, was homogeneous on SDS-PAGE, and was confirmed by Q-Tof Ultima API ESI/MS (TOF MS mode) mass spectrometry in 14243.8 Da. Multiple alignments of Bleu TX-III show high degree of homology with basic PLA2 myotoxins from other Bothrops venoms. Our studies on local and systemic myotoxicity “in vivo” reveal that Bleu TX-III is myotoxin with local but not systemic action due to the decrease in the plasmatic CK levels when Bleu TX-III is administrated by intravenous route in mice (dose 1 and 5 μg). And at a dose of 20 μg myotoxin behaves like a local and systemic action. Bleu TX-III induced moderate marked paw edema, evidencing the local increase in vascular permeability. The inflammatory events induced in the mice (I.M.) were investigated. The increase in the levels of IL-1, IL-6, and TNF-α was observed in the plasma. It is concluded that Bleu TX-III induces inflammatory events in this model. The enzymatic phospholipid hydrolysis may be relevant to these phenomena. Bothrops leucurus venom is still not extensively explored, and the knowledge of its toxins separately through the study of structure/function will contribute for a better understanding of its action mechanism. PMID:23509815

  17. Band structure engineering in topological insulator based heterostructures.

    PubMed

    Menshchikova, T V; Otrokov, M M; Tsirkin, S S; Samorokov, D A; Bebneva, V V; Ernst, A; Kuznetsov, V M; Chulkov, E V

    2013-01-01

    The ability to engineer an electronic band structure of topological insulators would allow the production of topological materials with tailor-made properties. Using ab initio calculations, we show a promising way to control the conducting surface state in topological insulator based heterostructures representing an insulator ultrathin films on the topological insulator substrates. Because of a specific relation between work functions and band gaps of the topological insulator substrate and the insulator ultrathin film overlayer, a sizable shift of the Dirac point occurs resulting in a significant increase in the number of the topological surface state charge carriers as compared to that of the substrate itself. Such an effect can also be realized by applying the external electric field that allows a gradual tuning of the topological surface state. A simultaneous use of both approaches makes it possible to obtain a topological insulator based heterostructure with a highly tunable topological surface state.

  18. Engineering the shape and structure of materials by fractal cut

    PubMed Central

    Cho, Yigil; Shin, Joong-Ho; Costa, Avelino; Kim, Tae Ann; Kunin, Valentin; Li, Ju; Lee, Su Yeon; Yang, Shu; Han, Heung Nam; Choi, In-Suk; Srolovitz, David J.

    2014-01-01

    In this paper we discuss the transformation of a sheet of material into a wide range of desired shapes and patterns by introducing a set of simple cuts in a multilevel hierarchy with different motifs. Each choice of hierarchical cut motif and cut level allows the material to expand into a unique structure with a unique set of properties. We can reverse-engineer the desired expanded geometries to find the requisite cut pattern to produce it without changing the physical properties of the initial material. The concept was experimentally realized and applied to create an electrode that expands to >800% the original area with only very minor stretching of the underlying material. The generality of our approach greatly expands the design space for materials so that they can be tuned for diverse applications. PMID:25422433

  19. Nuclear magnetic resonance structure of the III-IV-V three-way junction from the Varkud satellite ribozyme and identification of magnesium-binding sites using paramagnetic relaxation enhancement.

    PubMed

    Bonneau, Eric; Legault, Pascale

    2014-10-07

    The VS ribozyme is a catalytic RNA found within some natural isolates of Neurospora that is being used as a model system to improve our understanding of RNA structure, catalysis, and engineering. The catalytic domain contains five helical domains (SLII-SLVI) that are organized by two three-way junctions. The III-IV-V junction is required for high-affinity binding of the substrate domain (SLI) through formation of a kissing loop interaction with SLV. Here, we determine the high-resolution nuclear magnetic resonance (NMR) structure of a 47-nucleotide RNA containing the III-IV-V junction (J345). The J345 RNA adopts a Y-shaped fold typical of the family C three-way junctions, with coaxial stacking between stems III and IV and an acute angle between stems III and V. The NMR structure reveals that the core of the III-IV-V junction contains four stacked base triples, a U-turn motif, a cross-strand stacking interaction, an A-minor interaction, and a ribose zipper. In addition, the NMR structure shows that the cCUUGg tetraloop used to stabilize stem IV adopts a novel RNA tetraloop fold, different from the known gCUUGc tetraloop structure. Using Mn(2+)-induced paramagnetic relaxation enhancement, we identify six Mg(2+)-binding sites within J345, including one associated with the cCUUGg tetraloop and two with the junction core. The NMR structure of J345 likely represents the conformation of the III-IV-V junction in the context of the active VS ribozyme and suggests that this junction functions as a dynamic hinge that contributes to substrate recognition and catalysis. Moreover, this study highlights a new role for family C three-way junctions in long-range tertiary interactions.

  20. Applications of Substrate Integrated Waveguide (SIW) Structure in Microwave Engineering

    NASA Astrophysics Data System (ADS)

    Shen, Zhi

    This thesis is focused on some applications of the Substrate Integrated Waveguide (SIW) structure in microwave engineering. It is mainly divided into two parts, covering a dual-band high Q filter and a broadband high gain ring slot antenna, both of which are based on SIW resonators. This work indicates strong potential of SIW structure in communication system and discusses its unique advantages in detail. In the first part of the thesis, a dual-band high Q second order filter is designed to work at around 10 GHz and 14 GHz. SIW cavities are chosen in order to fulfill the low loss requirements. Two kinds of perturbation theories are applied in this structure to make two second order pass bands. Transmission lines of proper length are designed to connect the cavities together and make them work efficiently. In the second part of the thesis, a broadband high gain SIW ring slot antenna working at around 18 GHz is discussed. The bandwidth of the antenna is approximately 12.7% and the gain is around 7 dB. The cavity mode is properly chosen to reach the high antenna gain requirement. The working mechanism of its broadband property is discussed in detail to reach a reasonable argument.

  1. Spiky Fine Structure of Type III-like Radio Bursts in Absorption

    NASA Astrophysics Data System (ADS)

    Chernov, G. P.; Yan, Y. H.; Tan, C. M.; Chen, B.; Fu, Q. J.

    2010-03-01

    An uncommon fine structure in the radio spectrum consisting of bursts in absorption was observed with the Chinese Solar Broadband Radiospectrometer (SBRS) in the frequency range of 2.6 - 3.8 GHz during an X3.4/4B flare on 13 December 2006 in active region NOAA 10930 (S05W33). Usual fine structures in emission such as spikes, zebra stripes, and drifting fibers were observed at the peak of every new flare brightening. Within an hour at the decay phase of the event we observed bursts consisting of spikes in absorption, which pulsated periodically in frequency. Their instantaneous frequency bandwidths were found to be in the 75 MHz range. Moreover, in the strongest Type III-like bursts in absorption, the spikes showed stripes of the zebra-pattern (ZP) that drifted to higher frequencies. All spikes had the duration as short as down to the limit of the instrument resolution of ≈8 ms. The TRACE 195 Å images indicate that the magnetic reconnection at this moment occurred in the western edge of the flare loop arcade. Taking into account the presence of the reverse-drifting bursts in emission, in the course of the restoration of the magnetic structures in the corona, the acceleration of the beams of fast particles must have occurred both upward and downward at different heights. The upward beams will be captured by the magnetic trap, where the loss-cone distribution of fast particles (responsible for the emission of continuum and ZP) were formed. An additional injection of fast particles will fill the loss-cone later, breaking the loss-cone distribution. Therefore, the generation of continuum will be quenched at these moments, which was evidenced by the formation of bursts in absorption.

  2. Volatilization of Arsenic from Polluted Soil by Pseudomonas putida Engineered for Expression of the arsM Arsenic(III) S-Adenosine Methyltransferase Gene

    PubMed Central

    2015-01-01

    Even though arsenic is one of the most widespread environmental carcinogens, methods of remediation are still limited. In this report we demonstrate that a strain of Pseudomonas putida KT2440 endowed with chromosomal expression of the arsM gene encoding the As(III) S-adenosylmethionine (SAM) methyltransfase from Rhodopseudomonas palustris to remove arsenic from contaminated soil. We genetically engineered the P. putida KT2440 with stable expression of an arsM-gfp fusion gene (GE P. putida), which was inserted into the bacterial chromosome. GE P. putida showed high arsenic methylation and volatilization activity. When exposed to 25 μM arsenite or arsenate overnight, most inorganic arsenic was methylated to the less toxic methylated arsenicals methylarsenate (MAs(V)), dimethylarsenate (DMAs(V)) and trimethylarsine oxide (TMAs(V)O). Of total added arsenic, the species were about 62 ± 2.2% DMAs(V), 25 ± 1.4% MAs(V) and 10 ± 1.2% TMAs(V)O. Volatilized arsenicals were trapped, and the predominant species were dimethylarsine (Me2AsH) (21 ± 1.0%) and trimethylarsine (TMAs(III)) (10 ± 1.2%). At later times, more DMAs(V) and volatile species were produced. Volatilization of Me2AsH and TMAs(III) from contaminated soil is thus possible with this genetically engineered bacterium and could be instrumental as an agent for reducing the inorganic arsenic content of soil and agricultural products. PMID:25122054

  3. Structure of a Eukaryotic RNase III Post-Cleavage Complex Reveals a Double- Ruler Mechanism for Substrate Selection

    PubMed Central

    Liang, Yu-He; Lavoie, Mathieu; Comeau, Marc-Andre; Elela, Sherif Abou; Ji, Xinhua

    2014-01-01

    SUMMARY RNase III represents a family of dsRNA-specific endoribonucleases required for RNA maturation and gene regulation. The mechanism of action has been well characterized for the bacterial enzyme, but is not clear for eukaryotic RNase IIIs. Here, we describe the structure of Saccharomyces cerevisiae RNase III (Rnt1p) post-cleavage complex and explain the basis of its affinity for RNA stems capped with an NGNN tetraloop. The structure shows specific interactions between a new structural motif located at the end of Rnt1p dsRNA-binding domain (dsRBD) and the guanine nucleotide in the second position of the loop. Strikingly, structural and biochemical analyses indicate that the dsRBD and N-terminal domain function as two rulers measuring the distance between the tetraloop and the cleavage site. This unusual mechanism of substrate selectivity represents an example of the evolution of substrate selectivity and provides a framework for understanding the mechanism of action of eukaryotic RNase IIIs. PMID:24703949

  4. Engineering and Design: Stability Criteria for Existing Concrete Navigation Structures on Rock Foundations

    DTIC Science & Technology

    2007-11-02

    Engineering and Design STABILITY CRITERIA FOR EXISTING CONCRETE NAVIGATION STRUCTURES ON ROCK FOUNDATIONS Distribution Restriction Statement Approved...Title and Subtitle Engineering and Design: Stability Criteria for Existing Concrete Navigation Structures on Rock Foundations Contract Number Grant... CONCRETE NAVIGATION STRUCTURES ON ROCK FOUNDATIONS 1. Purpose. The purpose of this letter is to provide interim criteria and procedures for analyzing

  5. Structure of putrescine aminotransferase from Escherichia coli provides insights into the substrate specificity among class III aminotransferases.

    PubMed

    Cha, Hyung Jin; Jeong, Jae-Hee; Rojviriya, Catleya; Kim, Yeon-Gil

    2014-01-01

    YgjG is a putrescine aminotransferase enzyme that transfers amino groups from compounds with terminal primary amines to compounds with an aldehyde group using pyridoxal-5'-phosphate (PLP) as a cofactor. Previous biochemical data show that the enzyme prefers primary diamines, such as putrescine, over ornithine as a substrate. To better understand the enzyme's substrate specificity, crystal structures of YgjG from Escherichia coli were determined at 2.3 and 2.1 Å resolutions for the free and putrescine-bound enzymes, respectively. Sequence and structural analyses revealed that YgjG forms a dimer that adopts a class III PLP-dependent aminotransferase fold. A structural comparison between YgjG and other class III aminotransferases revealed that their structures are similar. However, YgjG has an additional N-terminal helical structure that partially contributes to a dimeric interaction with the other subunit via a helix-helix interaction. Interestingly, the YgjG substrate-binding site entrance size and charge distribution are smaller and more hydrophobic than other class III aminotransferases, which suggest that YgjG has a unique substrate binding site that could accommodate primary aliphatic diamine substrates, including putrescine. The YgjG crystal structures provide structural clues to putrescine aminotransferase substrate specificity and binding.

  6. Resonance assignments and secondary structure prediction of the As(III) metallochaperone ArsD in solution

    PubMed Central

    Ye, Jun; He, Yanan; Skalicky, Jack; Rosen, Barry P.; Stemmler, Timothy L.

    2012-01-01

    ArsD is a metallochaperone that delivers As(III) to the ArsA ATPase, the catalytic subunit of the ArsAB pump encoded by the arsRDABC operon of Escherichia coli plasmid R773. Conserved ArsD cysteine residues (Cys12, Cys13 and Cys18) construct the As(III) binding site of the protein, however a global structural understanding of this arsenic binding remains unclear. We have obtained NMR assignments for ArsD as a starting point for probing structural changes on the protein that occur in response to metalloid binding and upon formation of a complex with ArsA. The predicted solution structure of ArsD is in agreement with recently published crystallographic structural results. PMID:21063813

  7. Structural design of Stirling engine with free pistons

    NASA Astrophysics Data System (ADS)

    Matusov, Jozef; Gavlas, Stanislav; Malcho, Milan

    2014-08-01

    Stirling engine is a device that converts thermal energy to mechanical work, which is mostly used to drive a generator of electricity. Advantage of Stirling engine is that it works with closed-cycle, where working medium is regularly cooled and heated, which acts on the working piston. This engine can be made in three modifications - alpha, beta, gamma. This paper discusses the design of the gamma Stirling engine with free pistons.

  8. Synthesis and structure of dinuclear complexes of terbium(III) with 4-acetalbispyrazolone

    SciTech Connect

    Luqin Yang; Rudong Yang

    1994-12-01

    Two novel dinuclear complexes of terbium(III) with 1,5-bis(1`-phenyl-3`-methyl-5`-pyrazolone-4`)-1,5- pentanedione (H{sub 2}L), Tb{sub 2}L{sub 3}{center_dot}6H{sub 2}, Tb{sub 2}L{sub 3}{center_dot}5DMF, have been synthesized. The crystal structure of Tb{sub 2}L{sub 3}{center_dot}5DMF was determined by X-ray diffraction methods. Crystals are triclinic, space group P{rvec 1} with a = 16.957(5), b = 17.877(7), c = 18.269(2){Angstrom}, a = 110.35(2), {beta} = 101.29(2), {gamma} = 111.02(2){degrees}, V = 4511(6){Angstrom}{sup 3}, Mr = 2010.76 Z = 2, Dx = 1.48 g cm{sup -3}, {mu} = 16.45 cm{sub -1} F(000) = 2,052, R = 0.058 with 6574 reflections used in refinement. In the complex, L acts as a bridging ligand and bonds two terbium atoms with its two {beta}-diketone groups. Each terbium ion bonds to two DMF solvent molecules. The coordination number of the two terbium ions is eight. The eight oxygen atoms around the terbium make a distorted square antiprismatic coordination polyhedron.

  9. Structural chemistry of Au(III)-substituted Ba2YCu3O(7-delta)

    NASA Technical Reports Server (NTRS)

    Hepp, A. F.; Gaier, J. R.; Pouch, J. J.; Hambourger, P. D.

    1988-01-01

    A series of gold-substituted perovskite superconductors Ba2Y(Cu/1-x/Aux)3O(7-delta)(x = 0-0.1) was synthesized. For x = 0.1, there was no change in the a and b lattice parameters (a = 3.826 A and b = 3.889 A), but a 0.06 A c-axis expansion to 11.75 A was observed. Substituted gold was found to be trivalent by X-ray photoelectron spectroscopy. Replacing Cu(1) in the copper oxide chain with a slight reordering of oxygen is consistent with c-axis expansion. The formal charge of the site remains trivalent, while remaining Cu in the chains is reduced to Cu(I), resulting in an oxygen stoichiometry of less than 7. Finally, no large effect on Tc is observed (Tc = 89 K for x = 0.10), in contrast to the effect of a number of other metal ion dopants. These results are discussed relative to the chemistry of Au(III) and to the use of the metal in structures containing gold and ceramic superconductors.

  10. Type III phosphatidylinositol 4 kinases: structure, function, regulation, signalling and involvement in disease.

    PubMed

    Dornan, Gillian L; McPhail, Jacob A; Burke, John E

    2016-02-01

    Many important cellular functions are regulated by the selective recruitment of proteins to intracellular membranes mediated by specific interactions with lipid phosphoinositides. The enzymes that generate lipid phosphoinositides therefore must be properly positioned and regulated at their correct cellular locations. Phosphatidylinositol 4 kinases (PI4Ks) are key lipid signalling enzymes, and they generate the lipid species phosphatidylinositol 4-phosphate (PI4P), which plays important roles in regulating physiological processes including membrane trafficking, cytokinesis and organelle identity. PI4P also acts as the substrate for the generation of the signalling phosphoinositides phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3). PI4Ks also play critical roles in a number of pathological processes including mediating replication of a number of pathogenic RNA viruses, and in the development of the parasite responsible for malaria. Key to the regulation of PI4Ks is their regulation by a variety of both host and viral protein-binding partners. We review herein our current understanding of the structure, regulatory interactions and role in disease of the type III PI4Ks.

  11. Structure and conformation of (dibenzyldiaza-18-crown-6)-Nd(III) and Eu(III) thiocyanates: infrared spectroscopic and X-ray crystallographic studies

    NASA Astrophysics Data System (ADS)

    Saleh, Muhammad Idiris; Salhin, Abdussalam; Saad, Bahruddin; Fun, Hoong-Kun

    1999-01-01

    Dibenzyldiaza-18-crown-6 was utilised as a host to accommodate Nd(III) and Eu(III) metal ions together with thiocyanate as counter ion. The crystalline complexes formed were studied for their absorption in the infrared region and their crystalline structure by X-ray diffraction. The coordination of the metal ions to the counter ion and also to the donor atoms of the crown ether was clearly seen from the shift of the absorption band of the pure compound by up to nearly 15 cm -1. From these absorption it was found that each lanthanide ion was coordinated to six donor atoms (2 N and 4 O) from crown ether and three donor atoms, N from NCS -. This nine coordination number complex was found to have the stoichiometry of 1:1:3 (crown ether:lanthanide; NCS -). This ratio was further confirmed by X-ray crystallographic method. The lanthanide thiocyanate salts existed as an isolated (separate) entity in the center of the macrocyclic cavity. The three N atoms surrounded the Ln cation in a nearly planar trigonal arrangement with Ln ion being slightly out of plane. The trigonal plane was perpendicular to and bisects the plane of the macrocycle.

  12. Engineering High-Energy Interfacial Structures for High-Performance Oxygen-Involving Electrocatalysis.

    PubMed

    Guo, Chunxian; Zheng, Yao; Ran, Jingrun; Xie, Fangxi; Jaroniec, Mietek; Qiao, Shi-Zhang

    2017-03-24

    Engineering high-energy interfacial structures for high-performance electrocatalysis is achieved by chemical coupling of active CoO nanoclusters and high-index facet Mn3 O4 nano-octahedrons (hi-Mn3 O4 ). A thorough characterization, including synchrotron-based near edge X-ray absorption fine structure, reveals that strong interactions between both components promote the formation of high-energy interfacial Mn-O-Co species and high oxidation state CoO, from which electrons are drawn by Mn(III) -O present in hi-Mn3 O4 . The CoO/hi-Mn3 O4 demonstrates an excellent catalytic performance over the conventional metal oxide-based electrocatalysts, which is reflected by 1.2 times higher oxygen evolution reaction (OER) activity than that of Ru/C and a comparable oxygen reduction reaction (ORR) activity to that of Pt/C as well as a better stability than that of Ru/C (95 % vs. 81 % retained OER activity) and Pt/C (92 % vs. 78 % retained ORR activity after 10 h running) in alkaline electrolyte.

  13. Engineer Company Force Structure Force Modularization in Support of Decisive Action. Does the Corps of Engineers Need to Re-Structure Engineer Construction Companies Again in order to Support Decisive Actions?

    DTIC Science & Technology

    2012-05-16

    Point ATN Army Training Network AUTL Army Universal Task List BCT Brigade Combat Team BEB Brigade Combat Team Engineer Battalion BSO Battle...Additionally some measures of effectiveness are suggested for better tracking the progress of the engineer transformation and for structuring the engineer...

  14. Spectroscopic and quantum chemical study of the structure of a new paramagnetic dimeric palladium(II,III) complex with creatine

    NASA Astrophysics Data System (ADS)

    Mitewa, Mariana; Enchev, Venelin; Bakalova, Tatyana

    2002-05-01

    The structure and coordination mode of the newly synthesized dimeric paramagnetic Pd(II,III) complex are studied using magneto-chemical, EPR and IR spectroscopic methods. In order to perform reliable assignment of the IR bands, the structure and IR spectrum of the free creatine were calculated using ab initio method. For calculation of the configuration of its deprotonated and doubly deprotonated forms the semiempirical AM1 method was used.

  15. Structural investigations of PuIII phosphate by X-ray diffraction, MAS-NMR and XANES spectroscopy

    NASA Astrophysics Data System (ADS)

    Popa, Karin; Raison, Philippe E.; Martel, Laura; Martin, Philippe M.; Prieur, Damien; Solari, Pier L.; Bouëxière, Daniel; Konings, Rudy J. M.; Somers, Joseph

    2015-10-01

    PuPO4 was prepared by a solid state reaction method and its crystal structure at room temperature was solved by powder X-ray diffraction combined with Rietveld refinement. High resolution XANES measurements confirm the +III valence state of plutonium, in agreement with valence bond derivation. The presence of the americium (as β- decay product of plutonium) in the +III oxidation state was determined based on XANES spectroscopy. High resolution solid state 31P NMR agrees with the XANES results and the presence of a solid-solution.

  16. Core-sheath differentially biodegradable nanofiber structures for tissue engineering

    NASA Astrophysics Data System (ADS)

    Moghe, Ajit Keshav

    In recent years, it has been shown that the nanofiber structures prepared using electrospinning can serve as near ideal substrates for engineering tissues. Various biodegradable polymers of natural and synthetic origins have been used to construct the nanofiber scaffolds. The use of natural polymers is important in that they contain specific cell recognition sites that are capable of binding cells. Synthetic biodegradable polymers, on the other hand, can provide the necessary mechanical properties and their degradation rate can be controlled positively. When used alone, however, neither can provide an ideal structure for long-term development of tissues. This is because the regenerated natural polymers, although greatly biocompatible, are weak and degrade rapidly and uncontrollably, while the synthetic polymers, although mechanically more stable, are not as biocompatible. The focus of the current investigation was, therefore, to combine natural and synthetic polymers and to produce materials that have novel hybrid properties at the nano level. An optimum structure proposed was a differentially biodegradable bicomponent nanofiber with the sheath of natural and the core of synthetic polymers. Co-axial electrospinning was used to prepare the proposed core-sheath nanofibers. A major objective of the current research was to develop and optimize the technology to produce uniform bicomponent nanofibers of predictable morphologies by understanding the effects of various material and process variables such as solution concentration, solvent type, solution flow rate, and applied voltage. Two natural polymers (collagen and gelatin) and one synthetic biodegradable polymer (PCL) were used to develop the proposed structures. The factors that affected the bicomponent fiber formation were: interfacial tension between sheath and core solutions, volatility of the solvent, and applied voltage. By minimizing the interfacial tension, selecting the solvents with low vapor pressure, and

  17. Development and fabrication of structural components for a scramjet engine

    NASA Technical Reports Server (NTRS)

    Buchmann, O. A.

    1990-01-01

    A program broadly directed toward design and development of long-life (100 hours and 1,000 cycles with a goal of 1,000 hours and 10,000 cycles) hydrogen-cooled structures for application to scramjets is presented. Previous phases of the program resulted in an overall engine design and analytical and experimental characterization of selected candidate materials and concepts. The latter efforts indicated that the basic life goals for the program can be reached with available means. The main objective of this effort was an integrated, experimental evaluation of the results of the previous program phases. The fuel injection strut was selected for this purpose, including fabrication development and fabrication of a full-scale strut. Testing of the completed strut was to be performed in a NASA-Langley wind tunnel. In addition, conceptual designs were formulated for a heat transfer test unit and a flat panel structural test unit. Tooling and fabrication procedures required to fabricate the strut were developed, and fabrication and delivery to NASA of all strut components, including major subassemblies, were completed.

  18. Fabrication and photonics properties of III-V semiconductor nanowire structures

    NASA Astrophysics Data System (ADS)

    Lin, Tzu-ging

    III-V semiconductor nanowires (NWs) have shown great potential to be building blocks for optical, optoelectronic, and electronic devices due to their special transverse confinement of electrons and photons along the nanowire axis. In addition, semiconductor nanowires with subwavelength structures exhibit strong optical Mie resonance, making them ideal platforms for realizing novel optical devices, such as extreme solar energy absorbers and broadband light trapping devices. This special 1D optical Mie resonance can be enhanced by using semiconductor-core dielectric-shell (CS) and metal-core semiconductor-shell dielectric-outer shell (CSS) nanowire heterostructures. Those advantages can be even leveraged up by utilizing nanowire arrays, attributing to the increasing optical inter-wire interaction between incident light and nanostructures. However, to form a very thin, vertical IIIV nanowire array is challenging for both conventional top-down and bottom-up approaches due to the limitation of the resolution of lithographically defined masks and thermodynamic limits of growth direction and diameter of nanowires, respectively. By employing nanoscale self-mask effects, those limitations can be circumvented. In this dissertation, we presented a novel top-down etching method to fabricate very thin, high aspect ratio and vertical III-V nanowire arrays without lithographically defined masks. The mechanism of the formation of nanowire arrays was proposed and verified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in this work. Optical characterizations, such as optical reflectance and Raman spectroscopy, were also performed on those nanowire arrays. By employing those nanowire arrays, broadband light trapping can be achieved. Besides, the effects of contact electrodes, such as indium tin oxide (ITO), silver, and copper, on semiconductor nanowire solar cell devices with different bandgaps were also investigated with a focus on optical

  19. Engine-induced structural-borne noise in a general aviation aircraft

    NASA Technical Reports Server (NTRS)

    Unruh, J. F.; Scheidt, D. C.; Pomerening, D. J.

    1979-01-01

    Structural borne interior noise in a single engine general aviation aircraft was studied to determine the importance of engine induced structural borne noise and to determine the necessary modeling requirements for the prediction of structural borne interior noise. Engine attached/detached ground test data show that engine induced structural borne noise is a primary interior noise source for the single engine test aircraft, cabin noise is highly influenced by responses at the propeller tone, and cabin acoustic resonances can influence overall noise levels. Results from structural and acoustic finite element coupled models of the test aircraft show that wall flexibility has a strong influence on fundamental cabin acoustic resonances, the lightweight fuselage structure has a high modal density, and finite element analysis procedures are appropriate for the prediction of structural borne noise.

  20. Geometric and electronic structures of boron(III)-cored dyes tailored by incorporation of heteroatoms into ligands.

    PubMed

    Sun, Lin; Zhang, Fan; Wang, Xinyang; Qiu, Feng; Xue, Minzhao; Tregnago, Giulia; Cacialli, Franco; Osella, Silvio; Beljonne, David; Feng, Xinliang

    2015-03-01

    Complexation of a boron atom with a series of bidentate heterocyclic ligands successfully gives rise to corresponding BF2-chelated heteroarenes, which could be considered as novel boron(III)-cored dyes. These dye molecules exhibit planar structures and expanded π-conjugated backbones due to the locked conformation with a boron center. The geometric and electronic structures of these BF2 complexes can be tailored by embedding heteroatoms in the unique modes to form positional isomer and isoelectronic structures. The structure-property relationship is further elucidated by studying the photophysical properties, electrochemical behavior and quantum-chemical calculations.

  1. Structure and stability of hexa-aqua V(III) cations in vanadium redox flow battery electrolytes.

    PubMed

    Vijayakumar, M; Li, Liyu; Nie, Zimin; Yang, Zhenguo; Hu, JianZhi

    2012-08-07

    The vanadium(III) cation structure in mixed acid based electrolyte solution from vanadium redox flow batteries is studied by (17)O and (35/37)Cl nuclear magnetic resonance (NMR) spectroscopy, electronic spectroscopy and density functional theory (DFT) based computational modelling. Both computational and experimental results reveal that the V(III) species can complex with counter anions (sulfate/chlorine) depending on the composition of its solvation sphere. By analyzing the powder precipitate it was found that the formation of sulfate complexed V(III) species is the crucial process in the precipitation reaction. The precipitation occurs through nucleation of neutral species formed through deprotonation and ion-pair formation process. However, the powder precipitate shows a multiphase nature which warrants multiple reaction pathways for precipitation reaction.

  2. Forensic engineering of advanced polymeric materials. Part III - Biodegradation of thermoformed rigid PLA packaging under industrial composting conditions.

    PubMed

    Musioł, Marta; Sikorska, Wanda; Adamus, Grazyna; Janeczek, Henryk; Richert, Jozef; Malinowski, Rafal; Jiang, Guozhan; Kowalczuk, Marek

    2016-06-01

    This paper presents a forensic engineering study on the biodegradation behaviour of prototype packaging thermoformed from PLA-extruded film and plain PLA film under industrial composting conditions. Hydrolytic degradation in water was conducted for reference. The effects of composting duration on changes in molar mass, glass transition temperature and degree of crystallinity of the polymeric material were monitored using gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The chemical structure of water soluble degradation products of the polymeric material was determined using nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS). The results show that the biodegradation process is less dependent on the thermoforming process of PLA and more dependent on the composting/degradation conditions that are applied. The increase in the dispersity index, leading to the bimodal molar mass distribution profile, suggests an autocatalytic hydrolysis effect at the early stage of the composting process, during which the bulk hydrolysis mechanism dominantly operates. Both the prototype PLA-packaging and PLA rigid film samples were shown to have a gradual increase in opacity due to an increase in the degree of crystallinity.

  3. Automated output-only dynamic identification of civil engineering structures

    NASA Astrophysics Data System (ADS)

    Rainieri, C.; Fabbrocino, G.

    2010-04-01

    Modal-based damage detection algorithms are well-known techniques for structural health assessment, but they are not commonly used due to the lack of automated modal identification and tracking procedures. Development of such procedures is not a trivial task since traditional modal identification requires extensive interaction from an expert user. Nevertheless, computational efforts have to be carefully considered. If fast on-line data processing is crucial for quickly varying in time systems (such as a rocket burning fuel), a number of vibration-based condition monitoring applications are performed at very different time scales, resulting in satisfactory time steps for on-line data analysis. Moreover, promising results in the field of automated modal identification have been recently achieved. In the present paper, a literature review on this topic is presented and recent developments concerning fully automated output-only modal identification procedures are described. Some case studies are also reported in order to validate the approach. They are characterized by different levels of complexity, in terms of mode coupling, dynamic interaction effects and level of vibration. Advantages and drawbacks of the proposed approach will be pointed out with reference to available experimental results. The final objective is the implementation of a fully automated system for vibration-based structural health monitoring of civil engineering structures and identification of adequate requirements about sensor number and layout, record duration and hardware characteristics able to ensure a reliable low-cost health assessment of constructions. Results of application of the proposed methodology to modal parameter estimation in operational conditions and during ground motions induced by the recent L'Aquila earthquake will be finally presented and discussed.

  4. Spectroscopic, structural characterizations and antioxidant capacity of the chromium (III) niacinamide compound as a diabetes mellitus drug model

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Megharbel, Samy M.; Hussien, M. A.; Hamza, Reham Z.; Al-Omar, Mohamed A.; Naglah, Ahmed M.; Afifi, Walid M.; Kobeasy, Mohamed I.

    2017-02-01

    New binuclear chromium (III) niacinamide compound with chemical formula [Cr2(Nic)(Cl)6(H2O)4]·H2O was obtained upon the reaction of chromium (III) chloride with niacinamide (Nic) in methanol solvent at 60 °C. The proposed structure was discussed with the help of microanalytical analyses, conductivity, spectroscopic (FT-IR and UV-vis.), magnetic calculations, thermogravimetric analyses (TG/TGA), and morphological studies (X-ray of solid powder and scan electron microscopy. The infrared spectrum of free niacinamide in comparison with its chromium (III) compound indicated that the chelation mode occurs via both nitrogen atoms of pyridine ring and primary -NH2 group. The efficiency of chromium (III) niacinamide compound in decreasing of glucose level of blood and HbA1c in case of diabetic rats was checked. The ameliorating gluconeogenic enzymes, lipid profile and antioxidant defense capacities are considered as an indicator of the efficiency of new chromium (III) compound as antidiabetic drug model.

  5. Spectroscopic, structural characterizations and antioxidant capacity of the chromium (III) niacinamide compound as a diabetes mellitus drug model.

    PubMed

    Refat, Moamen S; El-Megharbel, Samy M; Hussien, M A; Hamza, Reham Z; Al-Omar, Mohamed A; Naglah, Ahmed M; Afifi, Walid M; Kobeasy, Mohamed I

    2017-02-15

    New binuclear chromium (III) niacinamide compound with chemical formula [Cr2(Nic)(Cl)6(H2O)4]·H2O was obtained upon the reaction of chromium (III) chloride with niacinamide (Nic) in methanol solvent at 60°C. The proposed structure was discussed with the help of microanalytical analyses, conductivity, spectroscopic (FT-IR and UV-vis.), magnetic calculations, thermogravimetric analyses (TG/TGA), and morphological studies (X-ray of solid powder and scan electron microscopy. The infrared spectrum of free niacinamide in comparison with its chromium (III) compound indicated that the chelation mode occurs via both nitrogen atoms of pyridine ring and primary -NH2 group. The efficiency of chromium (III) niacinamide compound in decreasing of glucose level of blood and HbA1c in case of diabetic rats was checked. The ameliorating gluconeogenic enzymes, lipid profile and antioxidant defense capacities are considered as an indicator of the efficiency of new chromium (III) compound as antidiabetic drug model.

  6. Structural and optical properties of II-VI and III-V compound semiconductors

    NASA Astrophysics Data System (ADS)

    Huang, Jingyi

    This dissertation is on the study of structural and optical properties of some III-V and II-VI compound semiconductors. The first part of this dissertation is a study of the deformation mechanisms associated with nanoindentation and nanoscratching of InP, GaN, and ZnO crystals. The second part is an investigation of some fundamental issues regarding compositional fluctuations and microstructure in GaInNAs and InAlN alloys. In the first part, the microstructure of (001) InP scratched in an atomic force microscope with a small diamond tip has been studied as a function of applied normal force and crystalline direction in order to understand at the nanometer scale the deformation mechanisms in the zinc-blende structure. TEM images show deeper dislocation propagation for scratches along <110> compared to <100>. High strain fields were observed in <100> scratches, indicating hardening due to locking of dislocations gliding on different slip planes. Reverse plastic flow have been observed in <110> scratches in the form of pop-up events that result from recovery of stored elastic strain. In a separate study, nanoindentation-induced plastic deformation has been studied in c-, a-, and m-plane ZnO single crystals and c-plane GaN respectively, to study the deformation mechanism in wurtzite hexagonal structures. TEM results reveal that the prime deformation mechanism is slip on basal planes and in some cases, on pyramidal planes, and strain built up along particular directions. No evidence of phase transformation or cracking was observed in both materials. CL imaging reveals quenching of near band-edge emission by dislocations. In the second part, compositional inhomogeneity in quaternary GaInNAs and ternary InAlN alloys has been studied using TEM. It is shown that exposure to antimony during growth of GaInNAs results in uniform chemical composition in the epilayer, as antimony suppresses the surface mobility of adatoms that otherwise leads to two-dimensional growth and

  7. Homometallic Dy(III) Complexes of Varying Nuclearity from 2 to 21: Synthesis, Structure, and Magnetism.

    PubMed

    Biswas, Sourav; Das, Sourav; Acharya, Joydev; Kumar, Vierandra; van Leusen, Jan; Kögerler, Paul; Herrera, Juan Manuel; Colacio, Enrique; Chandrasekhar, Vadapalli

    2017-04-11

    The synthesis, structure, and magnetic properties of four Dy(III) coordination compounds isolated as [Dy2 (LH2 )2 (μ2 -η(1) :η(1) -Piv)]Cl⋅2 MeOH⋅H2 O (1), [Dy4 (LH)2 (μ3 -OH)2 (Piv)4 (MeOH)2 ]⋅4 MeOH⋅2 H2 O (2), [Dy6 (LH2 )3 (tfa)3 (O3 PtBu)(Cl)3 ]Cl4 ⋅15.5 H2 O⋅4 MeOH⋅5 CHCl3 (3) and [Dy21 (L)7 (LH)7 (tfa)7 ]Cl7 ⋅15 H2 O⋅7 MeOH⋅12 CHCl3 (4) are reported (Piv=pivalate, tfa=1,1,1-trifluoroacetylacetone, O3 PtBu=tert-butylphosphonate). Among these, 3 displays an equilateral triangle topology with a side length of 9.541 Å and a rare pentagonal-bipyramidal Dy(3+) environment, whereas complex 4 exhibits a single-stranded nanowheel structure with the highest nuclearity known for a homometallic lanthanide cluster structure. A tentative model of the dc magnetic susceptibility and the low-temperature magnetization of compounds 1 and 2 indicates that the former exhibits weak ferromagnetic intramolecular exchange interaction between the Dy(3+) ions, whereas in the latter both intramolecular ferromagnetic and antiferromagnetic magnetic exchange interactions are present. Compounds 1, 3, and 4 exhibit frequency-dependent ac signals below 15 K at zero bias field, but without exhibiting any maximum above 2 K at frequencies up to 1400 Hz. The observed slow relaxation of the magnetization suggests that these compounds could exhibit single molecule magnet (SMM) behavior with either a thermal energy barrier for the reversal of the magnetization that is not high enough to block the magnetization above 2 K, or there exists quantum tunneling of the magnetization (QTM).

  8. Orthogonal higher order structure and confirmatory factor analysis of the French Wechsler Adult Intelligence Scale (WAIS-III).

    PubMed

    Golay, Philippe; Lecerf, Thierry

    2011-03-01

    According to the most widely accepted Cattell-Horn-Carroll (CHC) model of intelligence measurement, each subtest score of the Wechsler Intelligence Scale for Adults (3rd ed.; WAIS-III) should reflect both 1st- and 2nd-order factors (i.e., 4 or 5 broad abilities and 1 general factor). To disentangle the contribution of each factor, we applied a Schmid-Leiman orthogonalization transformation (SLT) to the standardization data published in the French technical manual for the WAIS-III. Results showed that the general factor accounted for 63% of the common variance and that the specific contributions of the 1st-order factors were weak (4.7%-15.9%). We also addressed this issue by using confirmatory factor analysis. Results indicated that the bifactor model (with 1st-order group and general factors) better fit the data than did the traditional higher order structure. Models based on the CHC framework were also tested. Results indicated that a higher order CHC model showed a better fit than did the classical 4-factor model; however, the WAIS bifactor structure was the most adequate. We recommend that users do not discount the Full Scale IQ when interpreting the index scores of the WAIS-III because the general factor accounts for the bulk of the common variance in the French WAIS-III. The 4 index scores cannot be considered to reflect only broad ability because they include a strong contribution of the general factor.

  9. Crystal structure of the coordination polymer [Fe(III) 2{Pt(II)(CN)4}3].

    PubMed

    Seredyuk, Maksym; Muñoz, M Carmen; Real, José A; Iskenderov, Turganbay S

    2015-01-01

    The title complex, poly[dodeca-μ-cyanido-diiron(III)triplat-inum(II)], [Fe(III) 2{Pt(II)(CN)4}3], has a three-dimensional polymeric structure. It is built-up from square-planar [Pt(II)(CN)4](2-) anions (point group symmetry 2/m) bridging cationic [Fe(III)Pt(II)(CN)4](+) ∞ layers extending in the bc plane. The Fe(II) atoms of the layers are located on inversion centres and exhibit an octa-hedral coordination sphere defined by six N atoms of cyanide ligands, while the Pt(II) atoms are located on twofold rotation axes and are surrounded by four C atoms of the cyanide ligands in a square-planar coordination. The geometrical preferences of the two cations for octa-hedral and square-planar coordination, respectively, lead to a corrugated organisation of the layers. The distance between neighbouring [Fe(III)Pt(II)(CN)4](+) ∞ layers corresponds to the length a/2 = 8.0070 (3) Å, and the separation between two neighbouring Pt(II) atoms of the bridging [Pt(II)(CN)4](2-) groups corresponds to the length of the c axis [7.5720 (2) Å]. The structure is porous with accessible voids of 390 Å(3) per unit cell.

  10. Innovative tissue engineering structures through advanced manufacturing technologies.

    PubMed

    Ciardelli, Gianluca; Chiono, Valeria; Cristallini, Caterina; Barbani, Niccoletta; Ahluwalia, Arti; Vozzi, Giovanni; Previti, Antonino; Tantussi, Giovanni; Giusti, Paolo

    2004-04-01

    Awide range of rapid prototyping (RP) techniques for the construction of three-dimensional (3-D) scaffolds for tissue engineering has been recently developed. In this study, we report and compare two methods for the fabrication of poly-(epsilon-caprolactone) and poly-(epsilon-caprolactone)-poly-(oxyethylene)-poly-(epsilon-caprolactone) copolymer scaffolds. The first technique is based on the use of a microsyringe and a computer-controlled three-axis micropositioner, which regulates motor speed and position. Polymer solutions are extruded through the needle of the microsyringe by the application of a constant pressure of 10-300 mm Hg, resulting in controlled polymer deposition of 5-600 microm lateral dimensions. The second method utilises the heating energy of a laser beam to sinter polymer microparticles according to computer-guided geometries. Materials may be fed either as dry powder or slurry of microparticles. Both powder granulometry and laser working parameters influence resolution (generally 300 microm x 700 microm), accuracy of sintering and surface and bulk properties of the final structures. The two RP methods allow the fabrication of 3-D scaffolds with a controlled architecture, providing a powerful means to study cell response to an environment similar to that found

  11. Purification, crystal structure determination and functional characterization of type III antifreeze proteins from the European eelpout Zoarces viviparus.

    PubMed

    Wilkens, Casper; Poulsen, Jens-Christian N; Ramløv, Hans; Lo Leggio, Leila

    2014-08-01

    Antifreeze proteins (AFPs) are essential components of many organisms adaptation to cold temperatures. Fish type III AFPs are divided into two groups, SP isoforms being much less active than QAE1 isoforms. Two type III AFPs from Zoarces viviparus, a QAE1 (ZvAFP13) and an SP (ZvAFP6) isoform, are here characterized and their crystal structures determined. We conclude that the higher activity of the QAE1 isoforms cannot be attributed to single residues, but rather a combination of structural effects. Furthermore both ZvAFP6 and ZvAFP13 crystal structures have water molecules around T18 equivalent to the tetrahedral-like waters previously identified in a neutron crystal structure. Interestingly, ZvAFP6 forms dimers in the crystal, with a significant dimer interface. The presence of ZvAFP6 dimers was confirmed in solution by native electrophoresis and gel filtration. To our knowledge this is the first report of dimerization of AFP type III proteins.

  12. Quantum mechanical treatment of As(3+)-thiol model compounds: implication for the core structure of As(III)-metallothionein.

    PubMed

    Garla, Roobee; Kaur, Narinder; Bansal, Mohinder Pal; Garg, Mohan Lal; Mohanty, Biraja Prasad

    2017-03-01

    Exposure to inorganic arsenic (As) is one of the major health concerns in several regions around the world. Binding of As(III) with thiols is central to the mechanisms related to its toxicity, detoxification, and therapeutic effects. Due to its high thiol content, metallothionein (MT) is presumed to play an important role in case of arsenic toxicity. Consequences of these As-thiol interactions are not yet clear due to various difficulties in the characterization of arsenic bound proteins by spectroscopic techniques. Computational modeling can be a reliable approach in predicting the molecular structures of such complexes. This paper presents the results of a systematic study on different As(III)-thiol model compounds conducted by both ab initio and DFT methods with different Gaussian type basis sets. Proficiency of these theoretical methods has been evaluated in terms of bond lengths, bond angles, free energy, partial atomic charges, computational cost, and comparison with the experimental data. It has been demonstrated that the DFT-B3LYP/6-311+G(3df) functional offers better accuracy in predicting the structure and the UV absorption spectra of As(III)-thiol complexes. The results of the present study also helps in defining the boundaries for the core of arsenic bound MT so that quantum mechanical/molecular mechanical (QM/MM) methods can be employed to predict the structural and functional aspects of the protein. Graphical Abstract Optimized structural parameters of As(3+)-thiol model compounds.

  13. Structural effects on the photophysical properties of mono-β-diketonate and bis-β-diketonate Eu(III) complexes.

    PubMed

    Zhu, Tianyu; Chen, Peng; Li, Hongfeng; Sun, Wenbin; Gao, Ting; Yan, Pengfei

    2015-06-28

    Two ligands, mono-β-diketone (p-methoxylbenzoyl)trifluoroacetone (MBTF) and bis-β-diketone 1,2-bis(4,4'-bis(4,4,4-trifluoro-1,3-dioxobutyl))phenoxyl ethane (BTPE) with similar chemical structures, have been designed and prepared for the purpose of building the relationship between the structures and luminescence properties of Eu(iii) complexes. Structures of the Eu(iii) complexes [Eu(MBTF)3(DMSO)(H2O)] and [Eu2(BTPE)3(DMSO)4] have been defined by single crystal X-ray crystallography. The mono-β-diketone complex [Eu(MBTF)3(DMSO)(H2O)] is a mononuclear structure, the central Eu(iii) ion is coordinated by eight oxygen atoms from three ligands and two solvents, in a distorted trigonal-dodecahedral (8-TDH) geometry. Whereas, the bis-β-diketone complex [Eu2(BTPE)3(DMSO)4] adopts a triple-stranded dinuclear structure in which the two Eu(iii) ions are helically wrapped by three bis-bidentate ligands, and each Eu(iii) ion is eight-coordinated by six oxygen atoms from the ligands and two oxygen atoms from the coordinated DMSO molecules, in a distorted square-antiprismatic (8-SAP) geometry. The photophysical properties related to the electronic transition are characterized by the absorbance spectra, the emission spectra, the emission quantum yields, the emission lifetimes, and the radiative (kr) and nonradiative rate constants (knr). The mono-β-diketone complex [Eu(MBTF)3(DMSO)(H2O)] offers a relatively high emission quantum yield (38%, in solid) compared to that observed in the bis-β-diketone complex [Eu2(BTPE)3(DMSO)4] (25%, in solid). This enhancement of emission quantum yield in the mono-β-diketone complex can be attributed to its lower site symmetry around the Eu(iii) ion, lower non-radiative rate constant and higher energy transfer efficiency from the ligand to the metal ion.

  14. Measuring Displacements in Engineering Structures by Means of a Coordinate Laser Station

    NASA Astrophysics Data System (ADS)

    Sztubecki, Jacek; Bujarkiewicz, Adam; Sztubecka, Małgorzata

    2016-12-01

    The application of geodetic methods to examine structures consists in the determination of their displacements relative to an established geodetic reference datum or in the definition of the geometry of their individual components. Such examinations form a picture of changes happening between specific points in time. Modern measurement technologies used in geodetic engineering enable undertaking more and more challenging measurements with increasing accuracy. The purpose of this article is to present a measurement technique involving a Leica TDRA 6000 total station to measure displacements in engineering structures. The station features a direct drive technology to achieve an accuracy of 0.25 mm in 3-dimensional measurements. Supported by appropriate software, the unit makes a perfect instrument for the monitoring of civil engineering structures. The article presents the results of measurement of static and dynamic displacements in a few engineering structures. The measurements were carried out both in laboratory conditions and on actual, operated civil engineering structures.

  15. Partitioning the effects of an ecosystem engineer: kangaroo rats control community structure via multiple pathways.

    PubMed

    Prugh, Laura R; Brashares, Justin S

    2012-05-01

    1. Ecosystem engineers impact communities by altering habitat conditions, but they can also have strong effects through consumptive, competitive and other non-engineering pathways. 2. Engineering effects can lead to fundamentally different community dynamics than non-engineering effects, but the relative strengths of these interactions are seldom quantified. 3. We combined structural equation modelling and exclosure experiments to partition the effects of a keystone engineer, the giant kangaroo rat (Dipodomys ingens), on plants, invertebrates and vertebrates in a semi-arid California grassland. 4. We separated the effects of burrow creation from kangaroo rat density and found that kangaroo rats increased the diversity and abundance of other species via both engineering and non-engineering pathways. 5. Engineering was the primary factor structuring plant and small mammal communities, whereas non-engineering effects structured invertebrate communities and increased lizard abundance. 6. These results highlight the importance of the non-engineering effects of ecosystem engineers and shed new light on the multiple pathways by which strong-interactors shape communities.

  16. Weibull-Based Design Methodology for Rotating Aircraft Engine Structures

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin; Hendricks, Robert C.; Soditus, Sherry

    2002-01-01

    The NASA Energy Efficient Engine (E(sup 3)-Engine) is used as the basis of a Weibull-based life and reliability analysis. Each component's life and thus the engine's life is defined by high-cycle fatigue (HCF) or low-cycle fatigue (LCF). Knowing the cumulative life distribution of each of the components making up the engine as represented by a Weibull slope is a prerequisite to predicting the life and reliability of the entire engine. As the engine Weibull slope increases, the predicted lives decrease. The predicted engine lives L(sub 5) (95 % probability of survival) of approximately 17,000 and 32,000 hr do correlate with current engine maintenance practices without and with refurbishment. respectively. The individual high pressure turbine (HPT) blade lives necessary to obtain a blade system life L(sub 0.1) (99.9 % probability of survival) of 9000 hr for Weibull slopes of 3, 6 and 9, are 47,391 and 20,652 and 15,658 hr, respectively. For a design life of the HPT disks having probable points of failure equal to or greater than 36,000 hr at a probability of survival of 99.9 %, the predicted disk system life L(sub 0.1) can vary from 9,408 to 24,911 hr.

  17. Crystal structure of the hemolytic lectin CEL-III isolated from the marine invertebrate Cucumaria echinata: implications of domain structure for its membrane pore-formation mechanism.

    PubMed

    Uchida, Tatsuya; Yamasaki, Takayuki; Eto, Seiichiro; Sugawara, Hajime; Kurisu, Genji; Nakagawa, Atsushi; Kusunoki, Masami; Hatakeyama, Tomomitsu

    2004-08-27

    CEL-III is a Ca(2+)-dependent and galactose-specific lectin purified from the sea cucumber, Cucumaria echinata, which exhibits hemolytic and hemagglutinating activities. Six molecules of CEL-III are assumed to oligomerize to form an ion-permeable pore in the cell membrane. We have determined the crystal structure of CELIII by using single isomorphous replacement aided by anomalous scattering in lead at 1.7 A resolution. CEL-III consists of three distinct domains as follows: the N-terminal two carbohydrate-binding domains (1 and 2), which adopt beta-trefoil folds such as the B-chain of ricin and are members of the (QXW)(3) motif family; and domain 3, which is a novel fold composed of two alpha-helices and one beta-sandwich. CEL-III is the first Ca(2+)-dependent lectin structure with two beta-trefoil folds. Despite sharing the structure of the B-chain of ricin, CEL-III binds five Ca(2+) ions at five of the six subdomains in both domains 1 and 2. Considering the relatively high similarity among the five subdomains, they are putative binding sites for galactose-related carbohydrates, although it remains to be elucidated whether bound Ca(2+) is directly involved in interaction with carbohydrates. The paucity of hydrophobic interactions in the interfaces between the domains and biochemical data suggest that these domains rearrange upon carbohydrate binding in the erythrocyte membrane. This conformational change may be responsible for oligomerization of CEL-III molecules and hemolysis in the erythrocyte membranes.

  18. Terbium(III) and yttrium(III) complexes with pyridine-substituted nitronyl nitroxide radical and different β-diketonate ligands. Crystal structures and magnetic and luminescence properties.

    PubMed

    Lannes, Anthony; Intissar, Mourad; Suffren, Yan; Reber, Christian; Luneau, Dominique

    2014-09-15

    A terbium(III) complex of nitronyl nitroxide free radical 2-(2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro1H-imidazolyl-1-oxy-3-oxide (NIT2Py), [Tb(acac)3NIT2Py]·0.5H2O (3) (acac = acetylacetonate), was synthesized for comparison with the previously reported [Tb(hfac)3NIT2Py]·0.5C7H16 (1) (hfac = hexafluoroacetylacetonate), together with their yttrium analogues [Y(hfac)3NIT2Py]·0.5C7H16 (2) and [Y(acac)3NIT2Py]·0.5H2O (4). The crystal structures show that in all complexes the nitronyl nitroxide radical acts as a chelating ligand. Magnetic studies show that 3 like 1 exhibits slow relaxation of magnetization at low temperature, suggesting single-molecule magnet behavior. The luminescence spectra show resolved vibronic structure with the main interval decreasing from 1600 cm(-1) to 1400 cm(-1) between 80 and 300 K. This effect is analyzed quantitatively using experimental Raman frequencies.

  19. V/III ratio effects on high quality InAlAs for quantum cascade laser structures

    NASA Astrophysics Data System (ADS)

    Demir, Ilkay; Elagoz, Sezai

    2017-04-01

    In this study we report the V/III ratio effects on growth, structural, optical and doping characteristics of low growth rate (∼1 Å/s) heteroepitaxial Metal Organic Chemical Vapor Deposition (MOCVD) grown InxAl1-xAs layers, a part of Quantum Cascade Laser (QCL) structures, on InP substrate. Especially photoluminescence (PL) properties of InAlAs-InP interface show strong dependence on AsH3 overpressure. We have shown that the V/III ratio with fixed metalorganic precursor flow is a crucial parameter on InxAl1-xAs layers to have a good material quality in terms of crystallinity, optical and electrical characteristics with and without doping.

  20. Reverse osmosis membrane composition, structure and performance modification by bisulphite, iron(III), bromide and chlorite exposure.

    PubMed

    Ferrer, O; Gibert, O; Cortina, J L

    2016-10-15

    Reverse osmosis (RO) membrane exposure to bisulphite, chlorite, bromide and iron(III) was assessed in terms of membrane composition, structure and performance. Membrane composition was determined by Rutherford backscattering spectrometry (RBS) and membrane performance was assessed by water and chloride permeation, using a modified version of the solution-diffusion model. Iron(III) dosage in presence of bisulphite led to an autooxidation of the latter, probably generating free radicals which damaged the membrane. It comprised a significant raise in chloride passage (chloride permeation coefficient increased 5.3-5.1 fold compared to the virgin membrane under the conditions studied) rapidly. No major differences in terms of water permeability and membrane composition were observed. Nevertheless, an increase in the size of the network pores, and a raise in the fraction of aggregate pores of the polyamide (PA) layer were identified, but no amide bond cleavage was observed. These structural changes were therefore, in accordance with the transport properties observed.

  1. Solution structure and dynamics of lanthanide complexes of the macrocyclic polyamino carboxylate DTPA-dien. NMR study and crystal structures of the lanthanum(III) and europium(III) complexes

    SciTech Connect

    Franklin, S.J.; Raymond, K.N.

    1994-12-07

    An 18-membered macrocyclic DTPA-bis(amide) ligand (DTPA = diethylenetriaminepentaacetic acid) containing a heteroatom in the amide link has been prepared via the condensation of DTPA-dianhydride and diethylenetriamine. The solution structures of the two isomeric pairs present in the Ln(III) complexes of DTPA-dien have been investigated by {sup 1}H NMR. The structures of the lanthanum(III) and europium(III) DTPA-dien complexes have been determined by X-ray analysis. [La(DTPA-dienH{sup +})H{sub 2}O]{sub 2}(CF{sub 3}SO{sub 3}{sup -}){sub 2}{center_dot}18H{sub 2}O (I) crystallizes as a carboxylate-bridged dimer about a center of inversion in the orthorhombic space group Pbca with a = 12.626(2) {angstrom}, b = 21.405(3) {angstrom}, c = 26.422(9) {angstrom}, and Z = 8. Each lanthanum ion is 11-coordinate with octadentate ligand coordination, an {eta}{sup 2} bridging carboxylate, and one water. [Eu(DTPA-dienH{sup +})]{sub 4}(CF{sub 3}SO{sub 3}{sup -}){sub 4}{center_dot}6NaCF{sub 3}SO{sub 3}{center_dot}20H{sub 2}O (II) crystallizes as a carboxylate-bridged tetramer with two crystallographically independent Eu(III) positions (Z = 8 for each) in the monoclinic space group C2/c: a = 30.94(1) {angstrom}, b = 23.456(3) {angstrom}, c = 22.611(4) {angstrom}, {beta} = 105.78(2){degrees}. The coordination geometries about Eu1 and Eu2 are nearly identical and are described as a nine-coordinate tricapped trigonal prism with octadentate ligand coordination plus an {eta}{sup 1} bridging carboxylate. The tendency to oligomerize is attributed to the constraints imposed by the macrocycle and the hydrogen bonding available with the link heteroatom. The structural differences between the two complexes are attributed to a difference in La(III) and Eu(III) ionic size.

  2. Crystal structures of type III{sub H} NAD-dependent D-3-phosphoglycerate dehydrogenase from two thermophiles

    SciTech Connect

    Kumar, S.M.; Pampa, K.J.; Manjula, M.; Hemantha Kumar, G.; Kunishima, Naoki; Lokanath, N.K.

    2014-08-15

    Highlights: • Determined the crystal structures of PGDH from two thermophiles. • Monomer is composed of nucleotide binding domain and substrate binding domain. • Crystal structures of type III{sub H} PGDH. - Abstract: In the L-Serine biosynthesis, D-3-phosphoglycerate dehydrogenase (PGDH) catalyzes the inter-conversion of D-3-phosphoglycerate to phosphohydroxypyruvate. PGDH belongs to 2-hydroxyacid dehydrogenases family. We have determined the crystal structures of PGDH from Sulfolobus tokodaii (StPGDH) and Pyrococcus horikoshii (PhPGDH) using X-ray diffraction to resolution of 1.77 Å and 1.95 Å, respectively. The PGDH protomer from both species exhibits identical structures, consisting of substrate binding domain and nucleotide binding domain. The residues and water molecules interacting with the NAD are identified. The catalytic triad residues Glu-His-Arg are highly conserved. The residues involved in the dimer interface and the structural features responsible for thermostability are evaluated. Overall, structures of PGDHs with two domains and histidine at the active site are categorized as type III{sub H} and such PGDHs structures having this type are reported for the first time.

  3. Synthesis, structural characterization, luminescent properties and theoretical study of three novel lanthanide metal-organic frameworks of Ho(III), Gd(III) and Eu(III) with 2,5-thiophenedicarboxylate anion

    SciTech Connect

    Marques, Lippy F.; Correa, Charlane C.; Ribeiro, Sidney J.L.; Santos, Molíria V. dos; Dutra, José Diogo L.; Freire, Ricardo O.; Machado, Flávia C.

    2015-07-15

    In this paper, the synthesis of three new metal-organic frameworks of lanthanides (LnMOFs) ([Ln{sub 2}(2,5-tdc){sub 3}(dmso){sub 2}]·H{sub 2}O){sub n} (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structure of (1) reveals that each lanthanide ion is seven-coordinated by oxygen atoms in an overall distorted capped trigonal – prismatic geometry. The 2,5-tdc{sup 2−} ligands connect four Ln(III) centers, adopting (κ{sup 1}–κ{sup 1})–(κ{sup 1}–κ{sup 1})–μ{sub 4} coordination mode, generating an 8-connected uninodal 3D network. In addition, theoretical studies for Eu(III) complex were performed using the Sparkle model for lanthanide complexes. - Graphical abstract: Three new metal-organic frameworks of lanthanides (LnMOFs) ([Ln{sub 2}(2,5-tdc){sub 3}(dmso){sub 2}]·H{sub 2}O){sub n} (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), were synthesized and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. - Highlights: • Three new LnMOFs were synthesized and fully characterized. • Ho{sup 3+}, Gd{sup 3+} and Eu{sup 3+} complexes photoluminescence properties were investigated. • Theoretical approaches for Eu{sup 3+} complex luminescence has been performed. • An energy level diagram is used to establish the ligand-to-metal energy transfer. • These metal−organic frameworks can act as light conversion molecular devices.

  4. Role of phospholipids of subunit III in the regulation of structural rearrangements in cytochrome c oxidase of Rhodobacter sphaeroides.

    PubMed

    Alnajjar, Khadijeh S; Cvetkov, Teresa; Prochaska, Lawrence

    2015-02-03

    Subunit III of cytochrome c oxidase possesses structural domains that contain conserved phospholipid binding sites. Mutations within these domains induce a loss of phospholipid binding, coinciding with decreased electron transfer activity. Functional and structural roles for phospholipids in the enzyme from Rhodobacter sphaeroides have been investigated. Upon the removal of intrinsic lipids using phospholipase A2, electron transfer activity was decreased 30-50%. Moreover, the delipidated enzyme exhibited turnover-induced, suicide inactivation, which was reversed by the addition of exogenous lipids, most specifically by cardiolipin. Cardiolipin exhibited two sites of interaction with the delipidated enzyme, a high-affinity site (Km = 0.14 μM) and a low-affinity site (Km = 26 μM). Subunit I of the delipidated enzyme exhibited a faster digestion rate when it was treated with α-chymotrypsin compared to that of the wild-type enzyme, suggesting that lipid removal induces a conformational change to expose the digestion sites further. Upon reaction of subunit III of the enzyme with a fluorophore (AEDANS), fluorescence anisotropy showed an increased rotational rate of the fluorophore in the absence of lipids, indicating increased flexibility of subunit III within the enzyme's tertiary structure. Additionally, Förster resonance energy transfer between AEDANS and a fluorescently labeled cardiolipin revealed that cardiolipin binds in the v-shaped cleft of subunit III in the delipidated enzyme and that it moves closer to the active site in subunit I upon a change in the redox state of the enzyme. In conclusion, these results show that the phospholipids regulate events occurring during electron transfer activity by maintaining the structural integrity of the enzyme at the active site.

  5. Complexation of Eu(III) with cucurbit[n]uril, n = 5 and 7: a thermodynamic and structural study.

    PubMed

    Rawat, Neetika; Kar, Aishwarya; Bhattacharyya, A; Rao, Ankita; Nayak, S K; Nayak, C; Jha, S N; Bhattacharyya, D; Tomar, B S

    2015-03-07

    Cucurbit[n]urils (CBn) are a new class of macrocyclic cage compounds capable of binding organic and inorganic species, owing to their unique pumpkin like structure comprising of both a hydrophobic cavity and a hydrophilic portal. The thermodynamics of the complexation of Eu(III) with CBn of a different cavity size viz. cucurbit[5]uril (CB5) and cucurbit[7]uril (CB7) has been studied by UV-Vis spectroscopy and calorimetry at 25 °C whereas the structure of the complexes was investigated using time resolved fluorescence spectroscopy (TRFS) and extended X-ray absorption fine structure spectroscopy (EXAFS) in a formic acid-water mixture (50 wt%). This is the first report on the structural investigation of Eu-CBn complexes in solution. The thermodynamic data (ΔG, ΔH and ΔS) for Eu(III) complexation with CBn reveal the formation of a 1 : 1 complex with CB5, while both 1 : 1 and 1 : 2 complexes are observed with CB7. The signatures of these species are observed in ESI-MS measurements, which corroborates with the species postulated in thermodynamic studies. The complexation reactions are found to be driven by ΔS as ΔH is either small negative or positive indicating the formation of inner sphere complexes, which is in line with TRFS and EXAFS results. These studies show that Eu(III) caps one of the CB5 portals by binding with all the carbonyl groups in the 1 : 1 Eu-CB5 complex, whereas in the 1 : 1 Eu-CB7 complex, Eu(III) interacts with only a few of the carbonyl groups of CB7. The computational studies (DFT calculations) on Eu-CB5 and Eu-CB7 complexes further support the experimental data.

  6. Effect of aging on the structure and phosphate retention of Fe(III)-precipitates formed by Fe(II) oxidation in water

    NASA Astrophysics Data System (ADS)

    Senn, Anna-Caterina; Kaegi, Ralf; Hug, Stephan J.; Hering, Janet G.; Mangold, Stefan; Voegelin, Andreas

    2017-04-01

    Iron(III)-precipitates formed by Fe(II) oxidation in aqueous solutions affect the cycling and impact of Fe and other co-precipitated elements in environmental systems. Fresh Fe(III)-precipitates are metastable and their transformation into more stable phases during aging may result in the release of initially co-precipitated ions. Phosphate, silicate, Mg and Ca play key roles in determining the structure and composition of fresh Fe(III)-precipitates. Here we examine how these ions affect the structure and phosphate retention of Fe(III)-precipitates formed by oxidation of 0.5 mM dissolved Fe(II) at pH 7.0 after aging for 30 days at 40 °C. Iron K-edge X-ray absorption spectroscopy (XAS) shows that aged precipitates consist of the same structural units as fresh precipitates: Amorphous Fe(III)- or Ca-Fe(III)-phosphate, ferrihydrite, and poorly crystalline lepidocrocite. Mg, Ca, and dissolved phosphate stabilize (Ca-)Fe(III)-phosphate against transformation into ferrihydrite. Silicate further attenuates (Ca-)Fe(III)-phosphate transformation. The crystallinity of lepidocrocite formed in phosphate- and silicate-free solutions slightly increases during aging. The transformation of Fe(III)- and Ca-Fe(III)-phosphate into ferrihydrite and ongoing ferrihydrite crystallization during aging result in the release of co-precipitated phosphate. Dissolved Ca on the other hand limits phosphate concentrations to values consistent with solubility control by octacalciumphosphate. Owing to the combined effects of Ca and silicate, phosphate is most effectively retained by Fe(III)-precipitates formed and aged in Ca- and silicate-containing solutions. The results from this study contribute to an improved understanding of the formation and transformation of Fe(III)-precipitates and emphasize that the complexity of Fe(III)-precipitate dynamics in the presence of multiple interfering solutes must be considered when addressing their impact on major and trace elements in environmental systems.

  7. Synthesis and Structural Characterization of a Series of Mn(III)-OR Complexes, Including a Water-Soluble Mn(III)-OH that Promotes Aerobic Hydrogen Atom Transfer

    PubMed Central

    Coggins, Michael K.; Brines, Lisa M.; Kovacs, Julie A.

    2013-01-01

    Hydrogen atom transfer reactions (HAT) are a class of proton-coupled electron transfer (PCET) reactions used in biology to promote substrate oxidation. The driving force for such reactions depend on both the oxidation potential of the catalyst and the pKa of the proton acceptor site. Both high-valent transition-metal oxo M(IV)=O (M= Fe, Mn) and lower-valent transition-metal hydroxo compounds M(III)–OH (M= Fe, Mn) have been shown to promote these reactions. Herein we describe the synthesis, structure and reactivity properties of a series of Mn(III)-OR compounds (R= pNO2Ph(5), Ph(6), Me(7), H(8)), some of which abstract H-atoms. The Mn(III)-OH complex 8 is water-soluble and represents a rare example of a stable mononuclear Mn(III)-OH. In water, the redox potential of 8 was found to be pH-dependent and the Pourbaix (Ep,c vs pH) diagram has a slope (52 mV/pH) that is indicative of the transfer a single proton with each electron (ie, PCET). The two compounds with the lowest oxidation potential, hydroxide and methoxide-bound 7 and 8 are found to oxidize TEMPOH, whereas the compounds with the highest oxidation potential, phenol-ligated 5 and 6, are shown to be unreactive. Hydroxide-bound 8 reacts with TEMPOH an order of magnitude faster than methoxide-bound 7. Kinetic data (kH/kD= 3.1 (8), kH/kD= 2.1 (7)) are consistent with concerted H-atom abstraction. The reactive species 8 can be aerobically regenerated in H2O, and at least 10 turnovers can be achieved without significant degradation of the “catalyst”. The linear correlation between redox potential and pH, obtained from the Pourbaix diagram, was used to calculate the BDFE= 74.0±0.5 kcal/mol for Mn(II)-OH2 in water, and in MeCN its BDFE was estimated to be (70.1 kcal/mol). The reduced protonated derivative of 8, [MnII(SMe2N4(tren))(H2O)]+ (9), was estimated to have a pKa of 21.2 in MeCN. The ability (7) and inability (5 and 6) of the other members of the series to abstract a H-atom from TEMPOH was used to

  8. Engineering, construction, and operations in space - III: Space '92; Proceedings of the 3rd International Conference, Denver, CO, May 31-June 4, 1992. Vols. 1 & 2

    NASA Technical Reports Server (NTRS)

    Sadeh, Willy Z. (Editor); Sture, Stein (Editor); Miller, Russell J. (Editor)

    1992-01-01

    The present volume on engineering, construction, and operations in space discusses surface structures on the moon and Mars, surface equipment, construction, and transportation on the moon and Mars, in situ materials use and processing, and space energy. Attention is given to such orbital structures as LEO and the space station, space mining and excavation, space materials, space automation and robotics, and space life support systems. Topics addressed include lunar-based astronomy, space systems integration, terrestrial support for space functions, and space education. Also discussed are space plans, policy, and history, space science and engineering, geoengineering and space exploration, and the construction and development of a human habitat on Mars.

  9. Structural investigations of Pu{sup III} phosphate by X-ray diffraction, MAS-NMR and XANES spectroscopy

    SciTech Connect

    Popa, Karin; Raison, Philippe E.; Martel, Laura; Martin, Philippe M.; Solari, Pier L.; Bouëxière, Daniel; Konings, Rudy J.M.; Somers, Joseph

    2015-10-15

    PuPO{sub 4} was prepared by a solid state reaction method and its crystal structure at room temperature was solved by powder X-ray diffraction combined with Rietveld refinement. High resolution XANES measurements confirm the +III valence state of plutonium, in agreement with valence bond derivation. The presence of the americium (as β{sup −} decay product of plutonium) in the +III oxidation state was determined based on XANES spectroscopy. High resolution solid state {sup 31}P NMR agrees with the XANES results and the presence of a solid-solution. - Graphical abstract: A full structural analysis of PuPO{sub 4} based on Rietveld analysis of room temperature X-ray diffraction data, XANES and MAS NMR measurements was performed. - Highlights: • The crystal structure of PuPO{sub 4} monazite is solved. • In PuPO{sub 4} plutonium is strictly trivalent. • The presence of a minute amount of Am{sup III} is highlighted. • We propose PuPO{sub 4} as a potential reference material for spectroscopic and microscopic studies.

  10. Band structure effects on resonant tunneling in III-V quantum wells versus two-dimensional vertical heterostructures

    NASA Astrophysics Data System (ADS)

    Campbell, Philip M.; Tarasov, Alexey; Joiner, Corey A.; Ready, W. Jud; Vogel, Eric M.

    2016-01-01

    Since the invention of the Esaki diode, resonant tunneling devices have been of interest for applications including multi-valued logic and communication systems. These devices are characterized by the presence of negative differential resistance in the current-voltage characteristic, resulting from lateral momentum conservation during the tunneling process. While a large amount of research has focused on III-V material systems, such as the GaAs/AlGaAs system, for resonant tunneling devices, poor device performance and device-to-device variability have limited widespread adoption. Recently, the symmetric field-effect transistor (symFET) was proposed as a resonant tunneling device incorporating symmetric 2-D materials, such as transition metal dichalcogenides (TMDs), separated by an interlayer barrier, such as hexagonal boron-nitride. The achievable peak-to-valley ratio for TMD symFETs has been predicted to be higher than has been observed for III-V resonant tunneling devices. This work examines the effect that band structure differences between III-V devices and TMDs has on device performance. It is shown that tunneling between the quantized subbands in III-V devices increases the valley current and decreases device performance, while the interlayer barrier height has a negligible impact on performance for barrier heights greater than approximately 0.5 eV.

  11. Band structure effects on resonant tunneling in III-V quantum wells versus two-dimensional vertical heterostructures

    SciTech Connect

    Campbell, Philip M.; Tarasov, Alexey; Joiner, Corey A.; Vogel, Eric M.; Ready, W. Jud

    2016-01-14

    Since the invention of the Esaki diode, resonant tunneling devices have been of interest for applications including multi-valued logic and communication systems. These devices are characterized by the presence of negative differential resistance in the current-voltage characteristic, resulting from lateral momentum conservation during the tunneling process. While a large amount of research has focused on III-V material systems, such as the GaAs/AlGaAs system, for resonant tunneling devices, poor device performance and device-to-device variability have limited widespread adoption. Recently, the symmetric field-effect transistor (symFET) was proposed as a resonant tunneling device incorporating symmetric 2-D materials, such as transition metal dichalcogenides (TMDs), separated by an interlayer barrier, such as hexagonal boron-nitride. The achievable peak-to-valley ratio for TMD symFETs has been predicted to be higher than has been observed for III-V resonant tunneling devices. This work examines the effect that band structure differences between III-V devices and TMDs has on device performance. It is shown that tunneling between the quantized subbands in III-V devices increases the valley current and decreases device performance, while the interlayer barrier height has a negligible impact on performance for barrier heights greater than approximately 0.5 eV.

  12. Crystal structure and solution species of Ce(III) and Ce(IV) formates: from mononuclear to hexanuclear complexes.

    PubMed

    Hennig, Christoph; Ikeda-Ohno, Atsushi; Kraus, Werner; Weiss, Stephan; Pattison, Philip; Emerich, Hermann; Abdala, Paula M; Scheinost, Andreas C

    2013-10-21

    Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution and the solid-state structures are surprisingly different. The species in aqueous solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) formate shows only mononuclear complexes, which is in agreement with the predicted mononuclear species of Ce(HCOO)(2+) and Ce(HCOO)2(+). In contrast, Ce(IV) formate forms in aqueous solution a stable hexanuclear complex of [Ce6(μ3-O)4(μ3-OH)4(HCOO)x(NO3)y](12-x-y). The structural differences reflect the different influence of hydrolysis, which is weak for Ce(III) and strong for Ce(IV). Hydrolysis of Ce(IV) ions causes initial polymerization while complexation through HCOO(-) results in 12 chelate rings stabilizing the hexanuclear Ce(IV) complex. Crystals were grown from the above-mentioned solutions. Two crystal structures of Ce(IV) formate were determined. Both form a hexanuclear complex with a [Ce6(μ3-O)4(μ3-OH)4](12+) core in aqueous HNO3/HCOOH solution. The pH titration with NaOH resulted in a structure with the composition [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)2(H2O)3]·(H2O)9.5, while the pH adjustment with NH3 resulted in [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)4]·(NO3)3(NH4)5(H2O)5. Furthermore, the crystal structure of Ce(III) formate, Ce(HCOO)3, was determined. The coordination polyhedron is a tricapped trigonal prism which is formed exclusively by nine HCOO(-) ligands. The hexanuclear Ce(IV) formate species from aqueous solution is widely preserved in the crystal structure, whereas the mononuclear solution species of Ce(III) formate undergoes a polymerization during the crystallization process.

  13. Composition and structure of Fe(III)-precipitates formed by Fe(II) oxidation in water at near-neutral pH: Interdependent effects of phosphate, silicate and Ca

    NASA Astrophysics Data System (ADS)

    Senn, Anna-Caterina; Kaegi, Ralf; Hug, Stephan J.; Hering, Janet G.; Mangold, Stefan; Voegelin, Andreas

    2015-08-01

    We studied the interdependent effects of phosphate, silicate and Ca on the formation of Fe(III)-precipitates by oxidation of 0.5 mM Fe(II) in near-neutral bicarbonate-buffered aqueous solutions at concentrations relevant for natural water resources. Complementary results obtained by a suite of analytical techniques including X-ray absorption spectroscopy and transmission electron microscopy showed that the ratio of initially dissolved phosphate over Fe(II) ((P/Fe)init) had a major impact on precipitate formation. At (P/Fe)init above a critical ratio ((P/Fe)crit) of ∼0.5 in 8 mM NaHCO3 and ∼0.8 in 4 mM Ca(HCO3)2 electrolyte, Fe(II) oxidation led to exclusive formation of amorphous basic Fe(III)-phosphate or Ca-Fe(III)-phosphate ((Ca-)Fe(III)-phosphate) with maximum precipitate P/Fe ratios ((P/Fe)ppt) of ∼0.7 in Na and ∼1.1 in Ca electrolyte. Enhanced phosphate uptake in the presence of Ca was due to phosphate-Ca interactions coupled to Fe precipitation, mainly formation of mitridatite-like Ca-Fe(III)-phosphate polymers and Ca-phosphate polymers. At (P/Fe)init < (P/Fe)crit, in the absence of silicate, (Ca-)Fe(III)-phosphate precipitation was followed by the formation of poorly crystalline lepidocrocite and concomitant transformation of the (Ca-)Fe(III)-phosphate into a phosphate-rich ferrihydrite-type precipitate with a (P/Fe)ppt of ∼0.25. In the presence of 0.5 mM silicate, initially formed (Ca-)Fe(III)-phosphate nanoparticles became coated with silicate-rich ferrihydrite during continuing Fe(II) oxidation and only limited transformation of the (Ca-)Fe(III)-phosphate occurred. The results from this study indicate the complexity of Fe(III)-precipitate formation in the presence of interfering solutes and its consequences for precipitate structure and phosphate sequestration. The findings provide a solid basis for further studies of the reactivity of different Fe(III)-precipitate types and for the systematic assessment of their impact on Fe, phosphate and

  14. Quantitative study of Au(III) and Pd(II) ion biosorption on genetically engineered Tobacco mosaic virus.

    PubMed

    Lim, Jung-Sun; Kim, Seung-Min; Lee, Sang-Yup; Stach, Eric A; Culver, James N; Harris, Michael T

    2010-02-15

    One major obstacle in the mineralization of metal onto biologically derived templates is the lack of fundamental information pertaining to the relationship between metal ion loading and overall metal deposition onto the biotemplate. This study focuses on Au(III) and Pd(II) biosorption on the genetically-modified model biological template Tobacco mosaic virus (TMV1Cys). Metal ion (Au(III) or Pd(II)) loading on the TMV1Cys template was measured as a function of the equilibrium concentration of Au(III) or Pd(II) ions in solution at several temperatures. In addition, the Pd(II) loading on the TMV-wild (wild-type TMV) and TMV1Cys were compared to estimate the improvement of metal ion loading by genetic modification of the biotemplate. The gold or palladium coatings on the TMV1Cys were prepared using various metal ion loadings. Results show, for a range of metal ion loadings, a positive correlation existed between the concentration of the metal ions and the coating density of the metals deposited on the virus surface.

  15. Factor Structure of the French Version of the Wechsler Adult Intelligence Scale-III. Validity Studies

    ERIC Educational Resources Information Center

    Gregoire, Jacques

    2004-01-01

    The standardization of the French version of the Wechsler Adult Intelligence Scale (WAIS-III) was conducted after carefully adapting the French version from the U.S. version and extensive field testing. The standardization sample was composed of 1,104 participants from 16 to 89 years. To assess the construct validity of the French version,…

  16. Structure and membrane remodeling activity of ESCRT-III helical polymers

    SciTech Connect

    McCullough, John; Clippinger, Amy K.; Talledge, Nathaniel; Skowyra, Michael L.; Saunders, Marissa G.; Naismith, Teresa V.; Colf, Leremy A.; Afonine, Pavel; Arthur, Christopher; Sundquist, Wesley I.; Hanson, Phyllis I.; Frost, Adam

    2015-12-18

    The endosomal sorting complexes required for transport (ESCRT) proteins mediate fundamental membrane remodeling events that require stabilizing negative membrane curvature. These include endosomal intralumenal vesicle formation, HIV budding, nuclear envelope closure, and cytokinetic abscission. ESCRT-III subunits perform key roles in these processes by changing conformation and polymerizing into membrane-remodeling filaments. Here, we report the 4 angstrom resolution cryogenic electron microscopy reconstruction of a one-start, double-stranded helical copolymer composed of two different human ESCRT-III subunits, charged multivesicular body protein 1B (CHMP1B) and increased sodium tolerance 1 (IST1). The inner strand comprises “open” CHMP1B subunits that interlock in an elaborate domain-swapped architecture and is encircled by an outer strand of “closed” IST1 subunits. Unlike other ESCRT-III proteins, CHMP1B and IST1 polymers form external coats on positively curved membranes in vitro and in vivo. In conclusion, our analysis suggests how common ESCRT-III filament architectures could stabilize different degrees and directions of membrane curvature.

  17. Structure and membrane remodeling activity of ESCRT-III helical polymers.

    PubMed

    McCullough, John; Clippinger, Amy K; Talledge, Nathaniel; Skowyra, Michael L; Saunders, Marissa G; Naismith, Teresa V; Colf, Leremy A; Afonine, Pavel; Arthur, Christopher; Sundquist, Wesley I; Hanson, Phyllis I; Frost, Adam

    2015-12-18

    The endosomal sorting complexes required for transport (ESCRT) proteins mediate fundamental membrane remodeling events that require stabilizing negative membrane curvature. These include endosomal intralumenal vesicle formation, HIV budding, nuclear envelope closure, and cytokinetic abscission. ESCRT-III subunits perform key roles in these processes by changing conformation and polymerizing into membrane-remodeling filaments. Here, we report the 4 angstrom resolution cryogenic electron microscopy reconstruction of a one-start, double-stranded helical copolymer composed of two different human ESCRT-III subunits, charged multivesicular body protein 1B (CHMP1B) and increased sodium tolerance 1 (IST1). The inner strand comprises "open" CHMP1B subunits that interlock in an elaborate domain-swapped architecture and is encircled by an outer strand of "closed" IST1 subunits. Unlike other ESCRT-III proteins, CHMP1B and IST1 polymers form external coats on positively curved membranes in vitro and in vivo. Our analysis suggests how common ESCRT-III filament architectures could stabilize different degrees and directions of membrane curvature.

  18. Status of ASME Section III Task Group on Graphite Support Core Structures

    SciTech Connect

    Robert L. Bratton; Tim D. Burchell

    2005-08-01

    This report outlines the roadmap that the ASME Project Team on Graphite Core Supports is pursuing to establish design codes for unirradiated and irradiated graphite core components during its first year of operation. It discusses the deficiencies in the proposed Section III, Division 2, Subsection CE graphite design code and the different approaches the Project Team has taken to address those deficiencies.

  19. Structure and membrane remodeling activity of ESCRT-III helical polymers

    DOE PAGES

    McCullough, John; Clippinger, Amy K.; Talledge, Nathaniel; ...

    2015-12-18

    The endosomal sorting complexes required for transport (ESCRT) proteins mediate fundamental membrane remodeling events that require stabilizing negative membrane curvature. These include endosomal intralumenal vesicle formation, HIV budding, nuclear envelope closure, and cytokinetic abscission. ESCRT-III subunits perform key roles in these processes by changing conformation and polymerizing into membrane-remodeling filaments. Here, we report the 4 angstrom resolution cryogenic electron microscopy reconstruction of a one-start, double-stranded helical copolymer composed of two different human ESCRT-III subunits, charged multivesicular body protein 1B (CHMP1B) and increased sodium tolerance 1 (IST1). The inner strand comprises “open” CHMP1B subunits that interlock in an elaborate domain-swapped architecturemore » and is encircled by an outer strand of “closed” IST1 subunits. Unlike other ESCRT-III proteins, CHMP1B and IST1 polymers form external coats on positively curved membranes in vitro and in vivo. In conclusion, our analysis suggests how common ESCRT-III filament architectures could stabilize different degrees and directions of membrane curvature.« less

  20. Structured system engineering methodologies used to develop a nuclear thermal propulsion engine

    NASA Technical Reports Server (NTRS)

    Corban, R.; Wagner, R.

    1993-01-01

    To facilitate the development of a space nuclear thermal propulsion engine for manned flights to Mars, requirements must be established early in the technology development cycle. The long lead times for the acquisition of the engine system and nuclear test facilities demands that the engine system size, performance and safety goals be defined at the earliest possible time. These systems are highly complex and require a large multidisciplinary systems engineering team to develop and track requirements, and to ensure that the as-built system reflects the intent of the mission. A methodology has been devised which uses sophisticated computer tools to effectively develop and interpret functional requirements, and furnish these to the specification level for implementation.

  1. Fundamentals of the Control of Gas-Turbine Power Plants for Aircraft. Part III Control of Jet Engines. Part 3; Control of Jet Engines

    NASA Technical Reports Server (NTRS)

    Kuehl, H.

    1947-01-01

    The basic principles of the control of TL ongincs are developed on .the basis of a quantitative investigation of the behavior of these behavior under various operating conditions with particular consideration of the simplifications pormissible in each case. Various possible means of control of jet engines are suggested and are illustrated by schematic designs.

  2. Defect-free zinc-blende structured InAs nanowires realized by in situ two V/III ratio growth in molecular beam epitaxy.

    PubMed

    Zhang, Zhi; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin

    2015-08-07

    In this study, we devised a two-V/III-ratio procedure to control the Au-assisted growth of defect-free InAs nanowires in molecular beam epitaxy. The demonstrated two V/III ratio procedure consists of a first high V/III ratio growth step to prepare the nanowire foundation on the substrate surface, followed by a low V/III ratio step to induce the nanowire growth. By manipulating the V/III ratios in different steps, we have achieved the controlled growth of pure defect-free zinc-blende structured InAs nanowires on the GaAs {1̄1̄1̄} substrates. This study provides an approach to control not only the crystal structure of semiconductor nanowires, but also their structural qualities.

  3. Structural Studies of E. coli Topoisomerase III-DNA Complexes Reveal a Novel Type IA Topoisomerase-DNA Conformational Intermediate

    SciTech Connect

    Changela, Anita; DiGate, Russell J.; Mondragon, Alfonso

    2010-03-05

    Escherichia coli DNA topoisomerase III belongs to the type IA family of DNA topoisomerases, which transiently cleave single-stranded DNA (ssDNA) via a 5{prime} phosphotyrosine intermediate. We have solved crystal structures of wild-type E. coli topoisomerase III bound to an eight-base ssDNA molecule in three different pH environments. The structures reveal the enzyme in three distinct conformational states while bound to DNA. One conformation resembles the one observed previously with a DNA-bound, catalytically inactive mutant of topoisomerase III where DNA binding realigns catalytic residues to form a functional active site. Another conformation represents a novel intermediate in which DNA is bound along the ssDNA-binding groove but does not enter the active site, which remains in a catalytically inactive, closed state. A third conformation shows an intermediate state where the enzyme is still in a closed state, but the ssDNA is starting to invade the active site. For the first time, the active site region in the presence of both the catalytic tyrosine and ssDNA substrate is revealed for a type IA DNA topoisomerase, although there is no evidence of ssDNA cleavage. Comparative analysis of the various conformational states suggests a sequence of domain movements undertaken by the enzyme upon substrate binding.

  4. Structural basis for the endoribonuclease activity of the type III-A CRISPR-associated protein Csm6

    PubMed Central

    Niewoehner, Ole; Jinek, Martin

    2016-01-01

    Prokaryotic CRISPR–Cas systems provide an RNA-guided mechanism for genome defense against mobile genetic elements such as viruses and plasmids. In type III-A CRISPR–Cas systems, the RNA-guided multisubunit Csm effector complex targets both single-stranded RNAs and double-stranded DNAs. In addition to the Csm complex, efficient anti-plasmid immunity mediated by type III-A systems also requires the CRISPR-associated protein Csm6. Here we report the crystal structure of Csm6 from Thermus thermophilus and show that the protein is a ssRNA-specific endoribonuclease. The structure reveals a dimeric architecture generated by interactions involving the N-terminal CARF and C-terminal HEPN domains. HEPN domain dimerization leads to the formation of a composite ribonuclease active site. Consistently, mutations of invariant active site residues impair catalytic activity in vitro. We further show that the ribonuclease activity of Csm6 is conserved across orthologs, suggesting that it plays an important functional role in CRISPR–Cas systems. The dimer interface of the CARF domains features a conserved electropositive pocket that may function as a ligand-binding site for allosteric control of ribonuclease activity. Altogether, our work suggests that Csm6 proteins provide an auxiliary RNA-targeting interference mechanism in type III-A CRISPR–Cas systems that operates in conjunction with the RNA- and DNA-targeting endonuclease activities of the Csm effector complex. PMID:26763118

  5. Crystal structure of [(1,2,3,4,11,12-η)-anthracene]tris-(tri-methyl-stann-yl)cobalt(III).

    PubMed

    Brennessel, William W; Ellis, John E

    2014-11-01

    The asymmetric unit of the title structure, [Co(η(6)-C14H10){Sn(CH3)3}3], contains two independent mol-ecules. Each anthracene ligand is η(6)-coordinating to a Co(III) cation and is nearly planar [fold angles of 5.4 (3) and 9.7 (3)°], as would be expected for its behaving almost entirely as a donor to a high-oxidation-state metal center. The slight fold in each anthracene ligand gives rise to slightly longer Co-C bond lengths to the ring junction carbon atoms than to the other four. Each Co(III) cation is further coordinated by three Sn(CH3)3 ligands, giving each mol-ecule a three-legged piano-stool geometry. In each of the two independent mol-ecules, the trio of SnMe3 ligands are modeled as disordered over two positions, rotated by approximately 30%, such that the C atoms nearly overlap. In one mol-ecule, the disorder ratio refined to 0.9365 (8):0.0635 (8), while that for the other refined to 0.9686 (8):0.0314 (8). The mol-ecules are well separated, and thus no significant inter-molecular inter-actions are observed. The compound is of inter-est as the first structure report of an η(6)-anthracene cobalt(III) complex.

  6. Structure of macrophage colony stimulating factor bound to FMS: Diverse signaling assemblies of class III receptor tyrosine kinases

    SciTech Connect

    Chen, Xiaoyan; Liu, Heli; Focia, Pamela J.; Shim, Ann Hye-Ryong; He, Xiaolin

    2009-06-12

    Macrophage colony stimulating factor (M-CSF), through binding to its receptor FMS, a class III receptor tyrosine kinase (RTK), regulates the development and function of mononuclear phagocytes, and plays important roles in innate immunity, cancer and inflammation. We report a 2.4 {angstrom} crystal structure of M-CSF bound to the first 3 domains (D1-D3) of FMS. The ligand binding mode of FMS is surprisingly different from KIT, another class III RTK, in which the major ligand-binding domain of FMS, D2, uses the CD and EF loops, but not the {beta}-sheet on the opposite side of the Ig domain as in KIT, to bind ligand. Calorimetric data indicate that M-CSF cannot dimerize FMS without receptor-receptor interactions mediated by FMS domains D4 and D5. Consistently, the structure contains only 1 FMS-D1-D3 molecule bound to a M-CSF dimer, due to a weak, hydrophilic M-CSF:FMS interface, and probably a conformational change of the M-CSF dimer in which binding to the second site is rendered unfavorable by FMS binding at the first site. The partial, intermediate complex suggests that FMS may be activated in two steps, with the initial engagement step distinct from the subsequent dimerization/activation step. Hence, the formation of signaling class III RTK complexes can be diverse, engaging various modes of ligand recognition and various mechanistic steps for dimerizing and activating receptors.

  7. Structural basis for the endoribonuclease activity of the type III-A CRISPR-associated protein Csm6.

    PubMed

    Niewoehner, Ole; Jinek, Martin

    2016-03-01

    Prokaryotic CRISPR-Cas systems provide an RNA-guided mechanism for genome defense against mobile genetic elements such as viruses and plasmids. In type III-A CRISPR-Cas systems, the RNA-guided multisubunit Csm effector complex targets both single-stranded RNAs and double-stranded DNAs. In addition to the Csm complex, efficient anti-plasmid immunity mediated by type III-A systems also requires the CRISPR-associated protein Csm6. Here we report the crystal structure of Csm6 from Thermus thermophilus and show that the protein is a ssRNA-specific endoribonuclease. The structure reveals a dimeric architecture generated by interactions involving the N-terminal CARF and C-terminal HEPN domains. HEPN domain dimerization leads to the formation of a composite ribonuclease active site. Consistently, mutations of invariant active site residues impair catalytic activity in vitro. We further show that the ribonuclease activity of Csm6 is conserved across orthologs, suggesting that it plays an important functional role in CRISPR-Cas systems. The dimer interface of the CARF domains features a conserved electropositive pocket that may function as a ligand-binding site for allosteric control of ribonuclease activity. Altogether, our work suggests that Csm6 proteins provide an auxiliary RNA-targeting interference mechanism in type III-A CRISPR-Cas systems that operates in conjunction with the RNA- and DNA-targeting endonuclease activities of the Csm effector complex.

  8. Materials and structural aspects of advanced gas-turbine helicopter engines

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Acurio, J.

    1979-01-01

    The key to improved helicopter gas turbine engine performance lies in the development of advanced materials and advanced structural and design concepts. The modification of the low temperature components of helicopter engines (such as the inlet particle separator), the introduction of composites for use in the engine front frame, the development of advanced materials with increased use-temperature capability for the engine hot section, can result in improved performance and/or decreased engine maintenance cost. A major emphasis in helicopter engine design is the ability to design to meet a required lifetime. This, in turn, requires that the interrelated aspects of higher operating temperatures and pressures, cooling concepts, and environmental protection schemes be integrated into component design. The major material advances, coatings, and design life-prediction techniques pertinent to helicopter engines are reviewed; the current state-of-the-art is identified; and when appropriate, progress, problems, and future directions are assessed.

  9. Two- and three-dimensional networks of gadolinium(III) with dicarboxylate ligands: synthesis, crystal structure, and magnetic properties.

    PubMed

    Cañadillas-Delgado, Laura; Pasan, Jorge; Fabelo, Oscar; Hernandez-Molina, María; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2006-12-25

    Four gadolinium(III) complexes with dicarboxylate ligands of formulas [Gd2(mal)3(H2O)5]n.2nH2O (1), [Gd2(mal)3(H2O)6]n (2), [NaGd(mal)(ox)(H2O)3]n (3), and [Gd2(ox)3(H2O)6]n.2.5nH2O (4) (mal = malonate; ox = oxalate) have been prepared, and their magnetic properties have been investigated as a function of the temperature. The structures of 1-3 have been determined by X-ray diffraction methods. The crystal structure of 4 was already known, and it is made of hexagonal layers of Gd atoms that are bridged by bis-bidentate oxalate. Compound 1 is isostructural with the europium(III) malonate complex [Eu2(mal)3(H2O)5]n.2nH2O,1 whose structure was reported elsewhere. The Gd atoms in 1 define a two-dimensional network where a terminal bidentate and bridging bidentate/bis-monodentate and tris-bidentate coordination modes of malonate occur. Compound 2 has a three-dimensional structure with a structural phase transition at 226 K, which involves a change of the space group from I2/a to Ia. Although its structure at room temperature was already known, that below 226 K was not. Pairs of Gd atoms with a double oxo-carboxylate bridge occur in both phases, and the main differences between both structures deal with the Gd environment and the H-bond pattern. 3 is also a three-dimensional compound, and it was obtained by reacting Gd(III) ions with malonic acid in a silica gel medium. Oxalic acid results as an oxidized product of the malonic acid, and single crystals of the heteroleptic complex were produced. The Gd atoms in 3 are connected through bis-bidentate oxalate and carboxylate-malonate bridges in the anti-anti and anti-syn coordination modes. Compounds 1 and 2 exhibit weak but significant ferromagnetic couplings between the Gd(III) ions through the single (1) and double (2) oxo-carboxylate bridges, whereas antiferromagnetic interactions across the bis-bidentate oxalate account for the overall antiferromagnetic behavior observed in 3 and 4.

  10. Role of structural noise in aircraft pressure cockpit from vibration action of new-generation engines

    NASA Astrophysics Data System (ADS)

    Baklanov, V. S.

    2016-07-01

    The evolution of new-generation aircraft engines is transitioning from a bypass ratio of 4-6 to an increased ratio of 8-12. This is leading to substantial broadening of the vibration spectrum of engines with a shift to the low-frequency range due to decreased rotation speed of the fan rotor, in turn requiring new solutions to decrease structural noise from engine vibrations to ensure comfort in the cockpits and cabins of aircraft.

  11. Thermal and structural assessments of a ceramic wafer seal in hypersonic engine

    NASA Technical Reports Server (NTRS)

    Tong, Mike; Steinetz, Bruce

    1991-01-01

    The thermal and structural performances of a ceramic wafer seal in a simulated hypersonic engine environment are numerically assessed. The effects of aerodynamic heating, surface contact conductance between the seal and its adjacent surfaces, flow of purge coolant gases, and leakage of hot engine flow path gases on the seal temperature were investigated from the engine inlet back to the entrance region of the combustion chamber. Finite element structural analyses, coupled with Weibull failure analyses, were performed to determine the structural reliability of the wafer seal.

  12. Thermal and structural assessments of a ceramic wafer seal in hypersonic engines

    NASA Technical Reports Server (NTRS)

    Tong, Mike T.; Steinetz, Bruce M.

    1991-01-01

    The thermal and structural performances of a ceramic wafer seal in a simulated hypersonic engine environment are numerically assessed. The effects of aerodynamic heating, surface contact conductance between the seal and its adjacent surfaces, flow of purge coolant gases, and leakage of hot engine flow path gases on the seal temperature were investigated from the engine inlet back to the entrance region of the combustion chamber. Finite element structural analyses, coupled with Weibull failure analyses, were performed to determine the structural reliability of the wafer seal.

  13. Investigating the growth, structural and electrical properties of III-V semiconductor nanopillars for the next-generation electronic and optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Lin, Andrew

    Extensive research efforts have been devoted to the study and development of III-V compound semiconductor nanowires (NWs) and nanopillars (NPs) because of their unique physical properties and ability to form high quality, highly lattice-mismatched axial and radial heterostructures. These advantages lead to precise nano-bandgap engineering to achieve new device functionalities. One unique and powerful approach to realize these NPs is by catalyst-free, selective-area epitaxy (SAE) via metal-organic chemical vapor deposition, in which the NP location and diameter can be precisely controlled lithographically. Early demonstrations of electronic and optoelectronic devices based on these NPs, however, are often inferior compared to their planar counterparts due to a few factors: (1) interface/surface states, (2) inaccurate doping calibration, and (3) increased carrier scattering and trapping from stacking fault formation in the NPs. In this study, the detailed growth mechanisms of different III-As, III-Sb and III-P NPs and their heterostructures are investigated. These NPs are then fabricated into single-NP field-effect transistors (FETs) to probe their electrical properties. It is shown that these devices are highly diameter-dependent, mainly because of the effects of surface states. By growing a high band-gap shell around the NP cores to passivate the surface, the device performance can be significantly improved. Further fabrication and characterization of vertical surround-gate FETs using a high-mobility InAs/InP NP channel is also discussed. Aside from the radial NP heterostructures, different approaches to achieve purely axial heterostructures in InAs/In(As)P materials are also presented with excellent interface quality. Both single barrier and double barrier structures are realized and fabricated into devices that show carrier transport characteristics over a barrier and even resonant tunneling behavior. Antimonide-based NPs are also studied for their immense

  14. The 3'-5' exonuclease site of DNA polymerase III from gram-positive bacteria: definition of a novel motif structure.

    PubMed

    Barnes, M H; Spacciapoli, P; Li, D H; Brown, N C

    1995-11-07

    The primary structure of the 3'-5' exonuclease (Exo) site of the Gram+ bacterial DNA polymerase III (Pol III) was examined by site-directed mutagenesis of Bacillus subtilis Pol III (BsPol III). It was found to differ significantly from the conventional three-motif substructure established for the Exo site of DNA polymerase I of Escherichia coli (EcPol I) and the majority of other DNA polymerase-exonucleases. Motifs I and II were conventionally organized and anchored functionally by the predicted carboxylate residues. However, the conventional downstream motif, motif III, was replaced by motif III epsilon, a novel 55-amino-acid (aa) segment incorporating three essential aa (His565, Asp533 and Asp570) which are strictly conserved in three Gram+ Pol III and in the Ec Exo epsilon (epsilon). Despite its unique substructure, the Gram+ Pol III-specific Exo site was conventionally independent of Pol, the site of 2'-deoxyribonucleoside 5-triphosphate (dNTP) binding and polymerization. The entire Exo site, including motif III epsilon, could be deleted without profoundly affecting the enzyme's capacity to polymerize dNTPs. Conversely, Pol and all other sequences downstream of the Exo site could be deleted with little apparent effect on Exo activity. Whether the three essential aa within the unique motif III epsilon substructure participate in the conventional two-metal-ion mechanism elucidated for the model Exo site of EcPol I, remains to be established.

  15. Model Compounds for Iron Proteins. Structures and Magnetic, Spectroscopic, and Redox Properties of Fe(III)M(II) and [Co(III)Fe(III)](2)O Complexes with (&mgr;-Carboxylato)bis(&mgr;-phenoxo)dimetalate and (&mgr;-Oxo)diiron(III) Cores.

    PubMed

    Dutta, Sujit K.; Werner, Rüdiger; Flörke, Ulrich; Mohanta, Sasankasekhar; Nanda, Kausik K.; Haase, Wolfgang; Nag, Kamalaksha

    1996-04-10

    A series of heterobimetallic complexes of the type [Fe(III)M(II)L(&mgr;-OAc)(OAc)(H(2)O)](ClO(4)).nH(2)O (2-5) and [{Fe(III)Co(III)L(&mgr;-OAc)(OAc)}(2)(&mgr;-O)](ClO(4))(2).3H(2)O (6) where H(2)L is a tetraaminodiphenol macrocyclic ligand and M(II) = Zn(2), Ni(3), Co(4), and Mn(5) have been synthesized and characterized. The (1)H NMR spectrum of 6 exhibits all the resonances between 1 and 12 ppm. The IR and UV-vis spectra of 2-5 indicate that in all the cases the metal ions have similar coordination environments. A disordered crystal structure determined for 3 reveals the presence of a (&mgr;-acetate)bis(&mgr;-phenoxide)-Ni(II)Fe(III) core, in which the two metal ions have 6-fold coordination geometry and each have two amino nitrogens and two phenolate oxygens as the in-plane donors; aside from the axial bridging acetate, the sixth coordination site of nickel(II) is occupied by the unidentate acetate and that of iron(III) by a water molecule. The crystal structure determination of 6 shows that the two heterobinuclear Co(III)Fe(III) units are bound by an Fe-O-Fe linkage. 6 crystallizes in the orthorhombic space group Ibca with a = 17.577(4) Å, b = 27.282(7) Å, c = 28.647(6) Å, and Z = 8. The two iron(III) centers in 6 are strongly antiferromagnetically coupled, J = -100 cm(-1) (H = -2JS(1).S(2)), whereas the other two S(1) = S(2) = (5)/(2) systems, viz. [Fe(2)(III)(HL)(2)(&mgr;-OH)(2)](ClO(4))(2) (1) and the Fe(III)Mn(II) complex (5), exhibit weak antiferromagnetic exchange coupling with J = -4.5 cm(-1) (1) and -1.8 cm(-1) (5). The Fe(III)Ni(II) (3) and Fe(III)Co(II) (4) systems, however, exhibit weak ferromagnetic behavior with J = 1.7 cm(-1) (3) and 4.2 cm(-1) (4). The iron(III) center in 2-5 exhibits quasi-reversible redox behavior between -0.44 and -0.48 V vs Ag/AgCl associated with reduction to iron(II). The oxidation of cobalt(II) in 4 occurs quasi-reversibly at 0.74 V, while both nickel(II) and manganese(II) in 3 and 5 undergo irreversible oxidation at 0

  16. Understanding lanthanoid(III) hydration structure and kinetics by insights from energies and wave functions.

    PubMed

    Zhang, Jun; Heinz, Norah; Dolg, Michael

    2014-07-21

    The hydration of all trivalent lanthanoid (Ln) ions is studied theoretically from two aspects: energy and wave function. With the help of the incremental scheme, for the first time the lanthanoid(III) aqua complexes are computed at the CCSD(T) level using large basis sets. These computations prove that SCS-MP2 is nearly as accurate as CCSD, thus enabling us to give the most accurate first principle hydration Gibbs free energies and reliable preferred coordination numbers (CNs) of lanthanoid(III) aqua complexes: 9, 8, and both, for light, heavy, and intermediate lanthanoids, respectively. Then a series of wave function analyses were performed to explore the deeper reasons for the preference of specific CNs. An unexpected observation is that as Ln goes from samarium to lutetium, the capping Ln-O bonds in nona-aqua lanthanoid complexes become weaker while they get shorter. Therefore, as the capping Ln-O bonds are getting easier to disrupt, heavier lanthanoids will prefer a low CN, i.e., 8. On the basis of this and previous work of other groups, a model for the water exchange kinetics of lanthanoid(III) ions is proposed. This model suggests that the capping Ln-O bonds of moderate strength, which occur for intermediate lanthanoids, are advantageous for the formation of a bicapped trigonal prism intermediate during water exchange. This explains some NMR experiments and, more importantly, an observation which puzzled investigators for a long time, i.e., that the exchange rate reaches a maximum for the middle region but is low at the beginning and end of the lanthanoid series. This nontrivial behavior of capping Ln-O bonds is interpreted and is believed to determine the hydration behavior of lanthanoid(III) ions.

  17. X-Ray Crystal Structure Analysis of Radical Bisphthalocyaninatoneodymium(III).

    DTIC Science & Technology

    1980-06-01

    prepared.7 Recently, intense attention has been also directed toward electrochromism of the bisphthalocyaninato- 8 lanthanide (III) complexes for color...uaercyclic planes. From E1 see surements, the title complex was found to contain an organic-free radical (S " 2.0029). Magnetic susceptibility muasuremente...also denonstrated that the titi complex contains one organic-free radical which could have an exchange Inter- action with f-electrens of the central

  18. III/V nano ridge structures for optical applications on patterned 300 mm silicon substrate

    NASA Astrophysics Data System (ADS)

    Kunert, B.; Guo, W.; Mols, Y.; Tian, B.; Wang, Z.; Shi, Y.; Van Thourhout, D.; Pantouvaki, M.; Van Campenhout, J.; Langer, R.; Barla, K.

    2016-08-01

    We report on an integration approach of III/V nano ridges on patterned silicon (Si) wafers by metal organic vapor phase epitaxy (MOVPE). Trenches of different widths (≤500 nm) were processed in a silicon oxide (SiO2) layer on top of a 300 mm (001) Si substrate. The MOVPE growth conditions were chosen in a way to guarantee an efficient defect trapping within narrow trenches and to form a box shaped ridge with increased III/V volume when growing out of the trench. Compressively strained InGaAs/GaAs multi-quantum wells with 19% indium were deposited on top of the fully relaxed GaAs ridges as an active material for optical applications. Transmission electron microcopy investigation shows that very flat quantum well (QW) interfaces were realized. A clear defect trapping inside the trenches is observed whereas the ridge material is free of threading dislocations with only a very low density of planar defects. Pronounced QW photoluminescence (PL) is detected from different ridge sizes at room temperature. The potential of these III/V nano ridges for laser integration on Si substrates is emphasized by the achieved ridge volume which could enable wave guidance and by the high crystal quality in line with the distinct PL.

  19. Synthesis, structure and spectroscopic study of Rh III polypyridine complexes with phenylcyanamide derivative ligands

    NASA Astrophysics Data System (ADS)

    Hadadzadeh, Hassan; Rezvani, Ali R.; Belanger-Gariepy, Francine

    2005-04-01

    Several new Rh III complexes, [Rh(tpy)(bpy)L](PF 6) 2 (tpy=2,2':6',2″-terpyridine, bpy=2,2'-bipyridine, and L=monoanions of phenylcyanamide(pcyd)), 4-methylphenylcyanamide (4-MePcyd), 2,4-dimethylphenylcyanamide (2,4-Me 2pcyd), 4-methoxyphenylcyanamide (4-MeOPcyd), 2-chlorophenylcyanamide (2-Clpcyd) and 2,5-dichlorophenylcyanamide (2,5-Cl 2pcyd) have been synthesized and characterized by elemental analysis, IR, 1H NMR and electronic absorption spectroscopies. ORTEP drawing of [Rh(tpy)(bpy)(2,5-Cl 2pcyd)](PF 6) 2·1/2CH 3CN shows three pyridyl rings of the tpy ligand that are nearly coplanar, as are the two rings of bpy. The anionic cyanamide group is coordinated end-on by the nitrile nitrogen to the Rh III. The Rh III-NCN bond is bent, having an angle of 125.4°. This bent bond is largely determined by the σ-bonding interaction of a cyanamide non-bonding electron pair in a sp 2 hybrid orbital.

  20. Equatorially connected diruthenium(II,III) units toward paramagnetic supramolecular structures with singular magnetic properties.

    PubMed

    Barral, M Carmen; Gallo, Teresa; Herrero, Santiago; Jiménez-Aparicio, Reyes; Torres, M Rosario; Urbanos, Francisco A

    2006-05-01

    The reaction of Ru2Cl(O2CMe)(DPhF)3 (DPhF = N,N'-diphenylformamidinate) with mono- and polycarboxylic acids gives a clean substitution of the acetate ligand, leading to the formation of complexes Ru2Cl(O2CC6H5)(DPhF)3 (1), Ru2Cl(O2CC6H4-p-CN)(DPhF)3 (2), [Ru2Cl(DPhF)3(H2O)]2(O2C)2 (3), [Ru2Cl(DPhF)3]2[C6H4-p-(CO2)2] (4), and [Ru2Cl(DPhF)3]3[C6H3-1,3,5-(CO2)3] (5). The preparation of [Ru2(NCS)(DPhF)3]3[C6H3-1,3,5-(CO2)3] (6) and {[Ru2(DPhF)3(H2O)]3[C6H3-1,3,5-(CO2)3]}(SO3CF3)3 (7) from 5 is also described. All complexes are characterized by elemental analysis, IR and electronic spectroscopy, mass spectrometry, cyclic voltammetry, and variable-temperature magnetic measurements. The crystal structure determinations of complexes 2.0.5THF and 3.THF.4H2O (THF = tetrahydrofuran) are reported. The reactions carried out demonstrate the high chemical stability of the fragment [Ru2(DPhF)3]2+, which is preserved in all tested experimental conditions. The stability of this fragment is also corroborated by the mass spectra. Electrochemical measurements reveal in all complexes one redox process due to the equilibrium Ru2(5+) <--> Ru2(6+). In the polynuclear complex 7, some additional oxidation processes are also observed that have been ascribed to the presence of two types of dimetallic units rather than two consecutive reversible oxidations. The magnetic behavior toward temperature for complexes 1-7 from 300 to 2 K is analyzed. Complexes 1-7 show low values of antiferromagnetic coupling in accordance with the molecular nature in 1 and 2 and the absence of important antiferromagnetic interaction through the carboxylate bridging ligands in 3-7, respectively. In addition, the magnetic properties of complex 7 do not correspond to any magnetic behavior described for diruthenium(II,III) complexes. The experimental data of compound 7 are simulated considering a physical mixture of S = 1/2 and 3/2 spin states. This magnetic study demonstrates the high sensitivity of the electronic

  1. Cylinder head fastening structure for internal combustion engines

    SciTech Connect

    Futakuchi, Y.; Oshiro, N.

    1988-01-26

    In a construction for an overhead cam internal combustion engine comprising a cylinder head adapted to be affixed to another component of the engine by at least one fastener having a tool receiving portion for tightening thereof and having a bearing cap affixed to the cylinder head and rotatably journaling the overhead camshaft, the improvement is described comprising the bearing cap having a portion overlying the fastener tool receiving portion, and means defining an access opening passing through the bearing cap and adapted to pass a tool for tightening of the fastener without removal of the bearing cap.

  2. Pre-Service Science Teachers' Cognitive Structures Regarding Science, Technology, Engineering, Mathematics (STEM) and Science Education

    ERIC Educational Resources Information Center

    Hacioglu, Yasemin; Yamak, Havva; Kavak, Nusret

    2016-01-01

    The aim of this study is to reveal pre-service science teachers' cognitive structures regarding Science, Technology, Engineering, Mathematics (STEM) and science education. The study group of the study consisted of 192 pre-service science teachers. A Free Word Association Test (WAT) consisting of science, technology, engineering, mathematics and…

  3. Effect of structural flexibility on the design of vibration-isolating mounts for aircraft engines

    NASA Technical Reports Server (NTRS)

    Phillips, W. H.

    1984-01-01

    Previous analyses of the design of vibration-isolating mounts for a rear-mounted engine to decouple linear and rotational oscillations are extended to take into account flexibility of the engine-mount structure. Equations and curves are presented to allow the design of mount systems and to illustrate the results for a range of design conditions.

  4. Crystal structure of the Csm3-Csm4 subcomplex in the type III-A CRISPR-Cas interference complex.

    PubMed

    Numata, Tomoyuki; Inanaga, Hideko; Sato, Chikara; Osawa, Takuo

    2015-01-30

    Clustered, regularly interspaced, short palindromic repeat (CRISPR) loci play a pivotal role in the prokaryotic host defense system against invading genetic materials. The CRISPR loci are transcribed to produce CRISPR RNAs (crRNAs), which form interference complexes with CRISPR-associated (Cas) proteins to target the invading nucleic acid for degradation. The interference complex of the type III-A CRISPR-Cas system is composed of five Cas proteins (Csm1-Csm5) and a crRNA, and targets invading DNA. Here, we show that the Csm1, Csm3, and Csm4 proteins from Methanocaldococcus jannaschii form a stable subcomplex. We also report the crystal structure of the M. jannaschii Csm3-Csm4 subcomplex at 3.1Å resolution. The complex structure revealed the presence of a basic concave surface around their interface, suggesting the RNA and/or DNA binding ability of the complex. A gel retardation analysis showed that the Csm3-Csm4 complex binds single-stranded RNA in a non-sequence-specific manner. Csm4 structurally resembles Cmr3, a component of the type III-B CRISPR-Cas interference complex. Based on bioinformatics, we constructed a model structure of the Csm1-Csm4-Csm3 ternary complex, which provides insights into its role in the Csm interference complex.

  5. Self-assembly synthesis, structural features, and photophysical properties of dilanthanide complexes derived from a novel amide type ligand: energy transfer from Tb(III) to Eu(III) in a heterodinuclear derivative.

    PubMed

    Gao, Cunji; Kirillov, Alexander M; Dou, Wei; Tang, Xiaoliang; Liu, Liangliang; Yan, Xuhuan; Xie, Yujie; Zang, Peixian; Liu, Weisheng; Tang, Yu

    2014-01-21

    A novel amide type ligand benzyl-N,N-bis[(2'-furfurylaminoformyl)phenoxyl)ethyl]-amine (L) has been designed and applied for the self-assembly generation of homodinuclear lanthanide coordination compounds [Ln2(μ2-L)2(NO3)6(EtOH)2] [Ln = Eu (1), Tb (2), and Gd (3)] and a heterodinuclear derivative [EuTb(μ2-L)2(NO3)6(EtOH)2] (4). All the complexes have been characterized by the X-ray single-crystal diffraction analyses. They are isostructural, crystallize in a monoclinic space group P21/c, and form [2 + 2] rectangular macrocycle structures. Compound 4 is the first example of a [2 + 2] rectangular macrocycle heterodinuclear EuTb complex assembled from an amide type ligand. In 4, the discrete 0D dimeric [EuTb(μ2-L)2(NO3)6(EtOH)2] units are extended, via the multiple N-H···O hydrogen bonds, into a 2D supramolecular network that has been topologically classified as a uninodal 4-connected underlying net with the sql [Shubnikov tetragonal plane net] topology. The triplet state ((3)ππ*) of L studied by the Gd(III) complex 3 demonstrated that the ligand beautifully populates Tb(III) emission (Φ = 52%), whereas the corresponding Eu(III) derivative 1 shows weak luminescence efficiency (Φ = 0.7%) because the triplet state of L has a poor match with (5)D1 energy level of Eu(III). Furthermore, the photoluminescent properties of heterodinuclear complex 4 have been compared with those of the analogous homodinuclear compounds. The quantum yield and lifetime measurements prove that energy transfer from Tb(III) to Eu(III) is being achieved, namely, that the Tb(III) center is also acting to sensitize the Eu(III) and enhancing Eu(III) emission in 4.

  6. Half-metallicity and electronic structures for carbon-doped group III-nitrides: Calculated with a modified Becke-Johnson potential

    NASA Astrophysics Data System (ADS)

    Fan, Shuai-wei; Wang, Ri-gao; Xu, Pemg

    2016-09-01

    The electronic structures and magnetism for carbon-doped group III-nitrides are investigated by utilizing the first principle method with the modified Becke-Johnson potential. Calculations show that carbon substituting cations (anions) would induce the group III-nitrides to be paramagnetic metals (half-metallic ferromagnets). Single carbon substituting nitrogen could produce 1.00μB magnetic moment. Electronic structures indicate that the carriers-mediated double-exchange interaction plays a crucial role in forming the ferromagnetism. Based on the mean-field theory, the Curie temperature for carbon-doped group III-nitrides would be above the room temperature. Negative chemical pair interactions imply that carbon dopants tend to form clustering distribution in group III-nitrides. The nitrogen vacancy would make the carbon-doped group III-nitrides lose the half-metallic ferromagnetism.

  7. Solution structure of Ln(III) complexes with macrocyclic ligands through theoretical evaluation of 1H NMR contact shifts.

    PubMed

    Rodríguez-Rodríguez, Aurora; Esteban-Gómez, David; de Blas, Andrés; Rodríguez-Blas, Teresa; Botta, Mauro; Tripier, Raphaël; Platas-Iglesias, Carlos

    2012-12-17

    Herein, we present a new approach that combines DFT calculations and the analysis of Tb(III)-induced (1)H NMR shifts to quantitatively and accurately account for the contact contribution to the paramagnetic shift in Ln(III) complexes. Geometry optimizations of different Gd(III) complexes with macrocyclic ligands were carried out using the hybrid meta-GGA TPSSh functional and a 46 + 4f(7) effective core potential (ECP) for Gd. The complexes investigated include [Ln(Me-DODPA)](+) (H(2)Me-DODPA = 6,6'-((4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(methylene))dipicolinic acid, [Ln(DOTA)(H(2)O)](-) (H(4)DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate), [Ln(DOTAM)(H(2)O)](3+) (DOTAM = 1,4,7,10- tetrakis[(carbamoyl)methyl]-1,4,7,10-tetraazacyclododecane), and related systems containing pyridyl units (Ln = Gd, Tb). Subsequent all-electron relativistic calculations based on the DKH2 approximation, or small-core ECP calculations, were used to compute the (1)H hyperfine coupling constants (HFCCs) at the ligand nuclei (A(iso) values). The calculated A(iso) values provided direct access to contact contributions to the (1)H NMR shifts of the corresponding Tb(III) complexes under the assumption that Gd and Tb complexes with a given ligand present similar HFCCs. These contact shifts were used to obtain the pseudocontact shifts, which encode structural information as they depend on the position of the nucleus with respect to the lanthanide ion. An excellent agreement was observed between the experimental and calculated pseudocontact shifts using the DFT-optimized geometries as structural models of the complexes in solution, which demonstrates that the computational approach used provides (i) good structural models for the complexes, (ii) accurate HFCCs at the ligand nuclei. The methodology presented in this work can be classified in the context of model-dependent methods, as it relies on the use of a specific molecular structure obtained from DFT

  8. Slave finite elements for nonlinear analysis of engine structures, volume 1

    NASA Technical Reports Server (NTRS)

    Gellin, S.

    1991-01-01

    A 336 degrees of freedom slave finite element processing capability to analyze engine structures under severe thermomechanical loading is presented. Description of the theoretical development and demonstration of that element is presented in this volume.

  9. Structural validity of the Dutch-language version of the WAIS-III in a psychiatric sample.

    PubMed

    van der Heijden, Paul; van den Bos, Pancras; Mol, Bart; Kessels, Roy P C

    2013-01-01

    The Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; Wechsler, 2008 ) no longer provides the "traditional" Verbal IQ and Performance IQ deviation scores. In the current study, we investigated the structural validity of these scores in the scale's predecessor, the WAIS-Third Edition (WAIS-III; Wechsler, 1997c ), which is still widely used in clinical practice, especially outside the United States. Confirmative (CFA) and exploratory factor analyses (EFA) were performed on WAIS-III data from a Dutch sample of 247 psychiatric patients. Four competing models were tested in the CFA on 11 subtests. The model that fit the data best was a model in which subtests loaded on the four factor indexes (i.e., 3 Verbal Comprehension subtests, 3 Perceptual Organization subtests, 3 Working Memory subtests, and 2 Processing Speed subtests) as proposed by the manual (Wechsler, 1997b ). In the EFA on 13 subtests with four factors extracted, all subtests were found to load on the factors in accordance with the WAIS-III test manual. However, Picture Arrangement, Arithmetic, and Picture Completion showed only moderate loadings on the proposed factors. Implications for clinical practice are discussed.

  10. Hydro-thermal synthesis and crystal structure of a new lanthanum(III) coordination polymer with fumaric acid.

    PubMed

    Anana, Hayet; Trifa, Chahrazed; Bouacida, Sofiane; Boudaren, Chaouki; Merazig, Hocine

    2015-05-01

    The title compound, poly[di-aqua-tris-(μ4-but-2-enedioato)(μ2-but-2-enedioic acid)dilanthanum(III)], [La2(C4H2O4)3(C4H4O4)(H2O)2] n , was synthesized by the reaction of lanthanum chloride penta-hydrate with fumaric acid under hydro-thermal conditions. The asymmetric unit comprises an La(III) cation, one and a half fumarate dianions (L (2-)), one a half-mol-ecule of fumaric acid (H2 L) and one coordinated water mol-ecule. Each La(III) cation has the same nine-coordinate environment and is surrounded by eight O atoms from seven distinct fumarate moieties, including one proton-ated fumarate unit and one water mol-ecule in a distorted tricapped trigonal-prismatic environment. The LaO8(H2O) polyhedra centres are edge-shared through three carboxyl-ate bridges of the fumarate ligand, forming chains in three dimensions to construct the MOF. The crystal structure is stabilized by O-H⋯O hydrogen-bond inter-actions between the coordin-ated water mol-ecule and the carboxyl-ate O atoms, and also between oxygen atoms of fumaric acid.

  11. Enhanced fluorescence and structural characteristics of carboxymethyl cellulose/Eu(III) nano-complex: Influence of reaction time.

    PubMed

    Ye, Jun; Wang, Ben; Xiong, Jian; Sun, Runcang

    2016-01-01

    CMC/Eu(III) nano-complexes were synthesized by reacting Eu(3+) with carboxymethyl cellulose (CMC). The SEM and EDS showed that particle size was less than 100nm and evenly distributed. FTIR and XPS indicated that the oxygen atoms in COO (-), OH, and COC were involved in the complexation with Eu(3+), yet, the O atoms were involved in different positions on anhydroglucose rings depending on reaction time. It was found that there were good energy matches between energy levels on ground state of CMC and (5)D0 Eu(III). Moreover, the intensities of (5)D0→(7)F2 of the nano-complexes were stronger than that of (5)D0→(7)F1, which indicated that the Eu(III) was not in the center of symmetry. The optimized reaction time was 35min, at this reaction time the smallest particle size and uniform distribution was obtained, the coordination structure was advantageous for the energy absorption transfer and emission.

  12. Engineering a naturally inactive isoform of type III antifreeze protein into one that can stop the growth of ice.

    PubMed

    Garnham, Christopher P; Nishimiya, Yoshiyuki; Tsuda, Sakae; Davies, Peter L

    2012-11-02

    Type III antifreeze proteins (AFPs) can be sub-divided into three classes of isoforms. SP and QAE2 isoforms can slow, but not stop, the growth of ice crystals by binding to pyramidal ice planes. The other class (QAE1) binds both pyramidal and primary prism planes and is able to halt the growth of ice. Here we describe the conversion of a QAE2 isoform into a fully-active QAE1-like isoform by changing four surface-exposed residues to develop a primary prism plane binding site. Molecular dynamics analyses suggest that the basis for gain in antifreeze activity is the formation of ice-like waters on the mutated protein surface.

  13. Structure and function of hainantoxin-III, a selective antagonist of neuronal tetrodotoxin-sensitive voltage-gated sodium channels isolated from the Chinese bird spider Ornithoctonus hainana.

    PubMed

    Liu, Zhonghua; Cai, Tianfu; Zhu, Qi; Deng, Meichun; Li, Jiayan; Zhou, Xi; Zhang, Fan; Li, Dan; Li, Jing; Liu, Yu; Hu, Weijun; Liang, Songping

    2013-07-12

    In the present study, we investigated the structure and function of hainantoxin-III (HNTX-III), a 33-residue polypeptide from the venom of the spider Ornithoctonus hainana. It is a selective antagonist of neuronal tetrodotoxin-sensitive voltage-gated sodium channels. HNTX-III suppressed Nav1.7 current amplitude without significantly altering the activation, inactivation, and repriming kinetics. Short extreme depolarizations partially activated the toxin-bound channel, indicating voltage-dependent inhibition of HNTX-III. HNTX-III increased the deactivation of the Nav1.7 current after extreme depolarizations. The HNTX-III·Nav1.7 complex was gradually dissociated upon prolonged strong depolarizations in a voltage-dependent manner, and the unbound toxin rebound to Nav1.7 after a long repolarization. Moreover, analysis of chimeric channels showed that the DIIS3-S4 linker was critical for HNTX-III binding to Nav1.7. These data are consistent with HNTX-III interacting with Nav1.7 site 4 and trapping the domain II voltage sensor in the closed state. The solution structure of HNTX-III was determined by two-dimensional NMR and shown to possess an inhibitor cystine knot motif. Structural analysis indicated that certain basic, hydrophobic, and aromatic residues mainly localized in the C terminus may constitute an amphiphilic surface potentially involved in HNTX-III binding to Nav1.7. Taken together, our results show that HNTX-III is distinct from β-scorpion toxins and other β-spider toxins in its mechanism of action and binding specificity and affinity. The present findings contribute to our understanding of the mechanism of toxin-sodium channel interaction and provide a useful tool for the investigation of the structure and function of sodium channel isoforms and for the development of analgesics.

  14. NASA Lewis Research Center/university graduate research program on engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1985-01-01

    NASA Lewis Research Center established a graduate research program in support of the Engine Structures Research activities. This graduate research program focuses mainly on structural and dynamics analyses, computational mechanics, mechanics of composites and structural optimization. The broad objectives of the program, the specific program, the participating universities and the program status are briefly described.

  15. NASA Lewis Research Center/University Graduate Research Program on Engine Structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1985-01-01

    NASA Lewis Research Center established a graduate research program in support of the Engine Structures Research activities. This graduate research program focuses mainly on structural and dynamics analyses, computational mechanics, mechanics of composites and structural optimization. The broad objectives of the program, the specific program, the participating universities and the program status are briefly described.

  16. Combination of X-ray crystallography, SAXS and DEER to obtain the structure of the FnIII-3, 4 domains of integrin α6β4

    SciTech Connect

    Alonso-García, Noelia; García-Rubio, Inés; Buey, Rubén M.; Urien, Hector; Sonnenberg, Arnoud; Jeschke, Gunnar; Pereda, José M. de

    2015-04-01

    The structure of the FnIII-3, 4 region of integrin β4 was solved using a hybrid approach that combines crystallographic structures, SAXS, DEER and molecular modelling. The structure helps in understanding how integrin β4 might bind to other hemidesmosomal proteins and mediate signalling. Integrin α6β4 is a major component of hemidesmosomes that mediate the stable anchorage of epithelial cells to the underlying basement membrane. Integrin α6β4 has also been implicated in cell proliferation and migration and in carcinoma progression. The third and fourth fibronectin type III domains (FnIII-3, 4) of integrin β4 mediate binding to the hemidesmosomal proteins BPAG1e and BPAG2, and participate in signalling. Here, it is demonstrated that X-ray crystallography, small-angle X-ray scattering and double electron–electron resonance (DEER) complement each other to solve the structure of the FnIII-3, 4 region. The crystal structures of the individual FnIII-3 and FnIII-4 domains were solved and the relative arrangement of the FnIII domains was elucidated by combining DEER with site-directed spin labelling. Multiple structures of the interdomain linker were modelled by Monte Carlo methods complying with DEER constraints, and the final structures were selected against experimental scattering data. FnIII-3, 4 has a compact and cambered flat structure with an evolutionary conserved surface that is likely to correspond to a protein-interaction site. Finally, this hybrid method is of general application for the study of other macromolecules and complexes.

  17. Cobalt(III) complexes as potential anticancer agents: Physicochemical, structural, cytotoxic activity and DNA/protein interactions.

    PubMed

    Thamilarasan, V; Sengottuvelan, N; Sudha, A; Srinivasan, P; Chakkaravarthi, G

    2016-09-01

    Cobalt(III) complexes (1-3) such as [Co(acac)(bpy)(N3)2·H2O] 1, [Co(acac)(en)(N3)2] 2, and [Co(acac)(2-pic)(N3)2] 3 (where, acac=acetylacetone, bpy=2.2'-bipyridine, en=ethylenediamine, 2-pic=2-picolylamine and NaN3=sodium azide) were synthesized and characterized. The structure of complexes (1-3) has been determined by single crystal X-ray diffraction studies and the configuration around cobalt(III) ion was distorted octahedral coordination geometry. Density functional theory calculations were performed to examine the molecular geometry and frontier molecular orbital properties of complexes (1-3). DNA binding properties of the cobalt(III) complexes with calf thymus DNA (CT-DNA) were investigated by UV-visible absorption, fluorescence, circular dichroism spectroscopy and viscosity measurements. The docking studies showed the preferred orientation of sterically acceptable Co(III) complexes (1, 2) inside the DNA through the mode of intercalation, whereas complex 3 exhibited minor groove binding modes. The intrinsic binding constants Kb of complexes (1-3) with CT-DNA were in the following order 1>3>2. Complexes (1-3) exhibit a good binding propensity to bovine serum albumin (BSA) and gel electrophoresis assay demonstrated that the complexes (1-3) promote the cleavage of the pBR322 DNA in the presence of 3-mercaptopropionic acid (MPA) and cleavage process was found to proceed by singlet oxygen cleavage mechanism. Further, the in vitro cytotoxicity studies of complexes (1-3) were tested on human breast cancer cell line (MCF-7).

  18. Expression, refolding and bio-structural analysis of a tetravalent recombinant dengue envelope domain III protein for serological diagnosis.

    PubMed

    Combe, Maxime; Lacoux, Xavier; Martinez, Jérôme; Méjan, Odile; Luciani, Françoise; Daniel, Soizic

    2017-03-06

    Dengue is a mosquito-borne disease caused by four genetically and serologically related viruses that affect several millions of people. Envelope domain III (EDIII) of the viral envelope protein contains dengue virus (DENV) type-specific and DENV complex-reactive antigenic sites. Here, we describe the expression in Escherichia coli, the refolding and bio-structural analysis of envelope domain III of the four dengue serotypes as a tetravalent dengue protein (EDIIIT2), generating an attractive diagnostic candidate. In vitro refolding of denatured EDIIIT2 was performed by successive dialysis with decreasing concentrations of chaotropic reagent and in the presence of oxidized glutathione. The efficiency of refolding was demonstrated by protein mobility shifting and fluorescent visualization of labeled cysteine in non-reducing SDS-PAGE. The identity and the fully oxidized state of the protein were verified by mass spectrometry. Analysis of the structure by fluorescence, differential scanning calorimetry and circular dichroism showed a well-formed structural conformation mainly composed of β-strands. A label-free immunoassay based on biolayer interferometry technology was subsequently used to evaluate antigenic properties of folded EDIIIT2 protein using a panel of dengue IgM positive and negative human sera. Our data collectively support the use of an oxidatively refolded EDIIIT2 recombinant chimeric protein as a promising antigen in the serological diagnosis of dengue virus infections.

  19. Structure of Salmonella FlhE, conserved member of a flagellar Type III secretion operon

    SciTech Connect

    Lee, Jaemin; Monzingo, Arthur F.; Keatinge-Clay, Adrian T.; Harshey, Rasika M.

    2014-12-26

    In this paper, the bacterial flagellum is assembled by a multicomponent transport apparatus categorized as a type III secretion system. The secretion of proteins that assemble into the flagellum is driven by the proton motive force. The periplasmic protein FlhE is a member of the flhBAE operon in the majority of bacteria where FlhE is found. FlhA and FlhB are established components of the flagellar type III secretion system. The absence of FlhE results in a proton leak through the flagellar system, inappropriate secretion patterns, and cell death, indicating that FlhE regulates an important aspect of proper flagellar biosynthesis. We isolated FlhE from the periplasm of Salmonella and solved its structure to 1.5 Å resolution. The structure reveals a β-sandwich fold, with no close structural homologs. Finally, possible roles of FlhE, including that of a chaperone, are discussed.

  20. The Influence of Channel Regulating Structures on Fish and Wildlife Habitat (GREAT-III).

    DTIC Science & Technology

    1982-08-01

    McGraw-Hill Book Company, Inc., New York, New York. 508 pp. Margalef, R . 1957. La Teoria de la Informacions en Ecologia. Mem. Real. Acad. Ciencias y...D-Ai412i 687 THE INFLUENCE OF CHANNEL REGULA AND HILDLIFE HABITAT (GREAT-III)(U) MISSOURI UNIV-ROLLA INST OF RIVER STUDIES R H SMITH ET AL. AUG...Roger H. Smith and Glendon T. Stevens, Jr. ’,cunent has been op-oved AND " r public release and sale; its daT:b i n isUliied The Missouri Department of

  1. Stress Engineering of Multi-pass Welds of Structural Steel to Enhance Structural Integrity

    NASA Astrophysics Data System (ADS)

    Ganguly, Supriyo; Sule, Jibrin; Yakubu, Mustapha Y.

    2016-08-01

    In multi-pass welding, the weld metal and the associated heat-affected zone are subjected to repeated thermal cycling from successive deposition of filler metals. The thermal straining results into multi-mode deformation of the weld metal which causes a variably distributed residual stress field through the thickness and across the weld of a multi-pass weldment. In addition to this, the as-welded fusion zone microstructure shows dendritic formation of grains and segregation of alloying element. This may result in formation of micro-corrosion cells and the problem would aggravate in case of highly alloyed materials. Local mechanical tensioning is an effective way of elimination of the weld tensile residual stress. It has been shown that application of cold rolling is capable not only of removing the residual stress, but depending on its magnitude it may also form beneficial compressive stress state. Multi-pass structural steel welds used as structural alloy in general engineering and structural applications. Such alloys are subjected to severe in-service degradation mechanisms e.g., corrosion and stress corrosion cracking. Welds and the locked-in residual stress in the welded area often initiate the defect which finally results in failure. In the present study, a multi-pass structural steel weld metal was first subjected to post-weld cold rolling which was followed by controlled heating by a fiber laser. Cold straining resulted in redistribution of the internal stress through the thickness and controlled laser processing helps in reforming of the grain structure. However, even with controlled laser, processing the residual stress is reinstated. Therefore, a strategy has been adopted to roll the metal post-laser processing so as to obtain a complete stress-free and recrystallized microstructure.

  2. Crystal structure of tris­(N-methyl­salicyl­aldiminato-κ2 N,O)chromium(III)

    PubMed Central

    Hilbert, Jessica; Kabus, Sven; Näther, Christian; Bensch, Wolfgang

    2015-01-01

    The crystal structure of the title compound, [Cr(C8H8NO)3], is isotypic with the vanadium(III) analogue. The asymmetric unit consists of one Cr3+ cation and three N-methyl­salicylaldiminate anions. The metal cation is octa­hedrally coordinated by three N,O-chelating N-methyl­salicylaldiminate ligands, leading to discrete and neutral complexes. In the crystal, neighbouring complexes are linked via C—H⋯O hydrogen-bonding inter­actions into chains propagating parallel to the c axis. PMID:26870448

  3. Syntheses, crystal structures and properties of new lead(II) or bismuth(III) selenites and tellurite.

    PubMed

    Zhang, Su-Yun; Hu, Chun-Li; Li, Pei-Xin; Jiang, Hai-Long; Mao, Jiang-Gao

    2012-08-21

    Four new lead(II) or bismuth(III) selenites and a tellurite, namely, Pb(3)(TeO(3))Cl(4), Pb(3)(SeO(3))(2)Br(2), Pb(2)Cd(3)(SeO(3))(4)I(2)(H(2)O), Pb(2)Ge(SeO(3))(4) and BiFe(SeO(3))(3), have been prepared and structurally characterized by single crystal X-ray diffraction (XRD) analyses. These compounds exhibit five different types of structures. The structure of Pb(3)(TeO(3))Cl(4) features a three-dimensional (3D) lead(II) chloride network with tellurite anions filling in the 1D tunnels of Pb(4) 4-member rings (MRs) along the c-axis. Pb(3)(SeO(3))(2)Br(2) contains a 3D network composed of lead(II) selenite layers interconnected by bromide anions. Pb(2)Cd(3)(SeO(3))(4)I(2)(H(2)O) is a 3D structure based on 2D cadmium(II) selenite layers which are further connected by 1D lead(II) iodide ladder chains with lattice water molecules located at the 1D tunnels of the structure. Pb(2)Ge(SeO(3))(4) features a 3D framework constructed by the alternate arrangement of lead(II) selenite layers and germanium(iv) selenite layers in the [100] direction. The structure of BiFe(SeO(3))(3) is built on the 3D anionic framework of ion(III) selenite with the bismuth(III) ions located at its Fe(6)Se(6) 12-MR tunnels. Pb(3)(TeO(3))Cl(4) (Pna2(1)) is polar and BiFe(SeO(3))(3) (P2(1)2(1)2(1)) is noncentrosymmetric. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicate that BiFe(SeO(3))(3) exhibits a weak SHG efficiency of about 0.2 × KH(2)PO(4) (KDP). Magnetic property measurements for BiFe(SeO(3))(3) show a dominant antiferromagnetic interaction with weak spin-canting at low temperatures. IR, UV-vis and thermogravimetric, as well as electronic structure calculations were also performed.

  4. Engineering approaches to illuminating brain structure and dynamics.

    PubMed

    Deisseroth, Karl; Schnitzer, Mark J

    2013-10-30

    Historical milestones in neuroscience have come in diverse forms, ranging from the resolution of specific biological mysteries via creative experimentation to broad technological advances allowing neuroscientists to ask new kinds of questions. The continuous development of tools is driven with a special necessity by the complexity, fragility, and inaccessibility of intact nervous systems, such that inventive technique development and application drawing upon engineering and the applied sciences has long been essential to neuroscience. Here we highlight recent technological directions in neuroscience spurred by progress in optical, electrical, mechanical, chemical, and biological engineering. These research areas are poised for rapid growth and will likely be central to the practice of neuroscience well into the future.

  5. Structural Engineering of Microwave Antennas, Chapters 1-4

    NASA Technical Reports Server (NTRS)

    Levy, R.

    1994-01-01

    This paper discusses computer-aided design procedures for antenna reflector structures and related components. Examples in the paper illustrate effective design improvement for structures with several thousand degrees of freedom and within reasonable computing times.

  6. Engineering of Sensor Network Structure for Dependable Fusion

    DTIC Science & Technology

    2014-08-15

    Transient Time Series for Fault Detection in Gas Turbine Engines, Journal of Dynamic Systems , Measurement, and Control, (01 2013): 0. doi: 10.1115...China. : , Soumik Sarkar, Dheeraj S. Singh, Abhishek Srivastav, Asok Ray. Semantic Sensor Fusion for Fault Diagnosis in Aircraft Gas Turbine...2. Online void fraction measurement in two phase flow systems via nonlinear filtering of ultrasonic signals (Dr. Ray, PSU) 3. Diagnosis and

  7. The structures of CyMe4-BTBP complexes of americium(iii) and europium(iii) in solvents used in solvent extraction, explaining their separation properties.

    PubMed

    Ekberg, Christian; Löfström-Engdahl, Elin; Aneheim, Emma; Foreman, Mark R StJ; Geist, Andreas; Lundberg, Daniel; Denecke, Melissa; Persson, Ingmar

    2015-11-14

    Separation of trivalent actinoid (An(iii)) and lanthanoid (Ln(iii)) ions is extremely challenging due to their similar ionic radii and chemical properties. Poly-aromatic nitrogen compounds acting as tetradentate chelating ligands to the metal ions in the extraction, have the ability to sufficiently separate An(iii) from Ln(iii). One of these compounds, 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzol[1,2,4]triazin-3-yl)[2,2]bipyridine, CyMe4-BTBP, has proven to be resistant towards acidic environments and strong radiation from radioactive decomposition. EXAFS studies of the dicomplexes of CyMe4-BTBP with americium(iii) and europium(iii) in nitrobenzene, cyclohexanone, 1-hexanol, 1-octanol and malonamide (DMDOHEMA) in 1-octanol have been carried out to get a deeper understanding of the parameters responsible for the separation. The predominating complexes independent of solvent used are [Am(CyMe4-BTBP)2(NO3)](2+) and [Eu(CyMe4-BTBP)2](3+), respectively, which are present as outer-sphere ion-pairs with nitrate ions in the studied solvents with low relative permittivity. The presence of a nitrate ion in the first coordination sphere of the americium(iii) complex compensates the charge density of the complex considerably in comparison when only outer-sphere ion-pairs are formed as for the [Eu(CyMe4-BTBP)2](3+) complex. The stability and solubility of a complex in a solvent with low relative permittivity increase with decreasing charge density. The [Am(CyMe4-BTBP)2(NO3)](2+) complex will therefore be increasingly soluble and stabilized over the [Eu(CyMe4-BTBP)2](3+) complex in solvents with decreasing relative permittivity of the solvent. The separation of americium(iii) from europium(iii) with CyMe4-BTBP as extraction agent will increase with decreasing relative permittivity of the solvent, and thereby also with decreasing solubility of CyMe4-BTBP. The choice of solvent is therefore a balance of a high separation factor and sufficient solubility of the CyMe4-BTBP

  8. Structural Properties of 2/2 Hemoglobins: The Group III Protein from Helicobacter hepaticus

    PubMed Central

    Nothnagel, Henry J.; Winer, Benjamin Y.; Vuletich, David A.; Pond, Matthew P.; Lecomte, Juliette T.J.

    2011-01-01

    Summary The ε-proteobacterium Helicobacter hepaticus (Hh) contains a gene coding for a hemoglobin (Hb). The protein belongs to the 2/2 Hb lineage and is representative of Group III, a set of Hbs about which little is known. An expression and purification procedure was developed for Hh Hb. Electronic absorption and NMR spectra were used to characterize ligation states of the ferric and ferrous protein. The pKa of the acid/alkaline transition of ferric Hh Hb was 7.3, an unusually low value. NMR analysis of the cyanomet complex showed the orientation of the heme group to be reversed compared to most Group I and II 2/2 Hbs. Ferrous Hh Hb formed a stable cyanide complex that yielded NMR spectra similar to those of the carbonmonoxy complex. All forms of Hh Hb self-associated at NMR concentrations. Comparison was made to the related Campylobacter jejuni 2/2 Hb (Ctb), and the amino acid conservation pattern of Group III was re-inspected to help in the generalization of structure–function relationships. PMID:21445851

  9. Syntheses, crystal structures, reactivity, and photochemistry of gold(III) bromides bearing N-heterocyclic carbenes.

    PubMed

    Hirtenlehner, Christa; Krims, Charlotte; Hölbling, Johanna; List, Manuela; Zabel, Manfred; Fleck, Michel; Berger, Raphael J F; Schoefberger, Wolfgang; Monkowius, Uwe

    2011-10-14

    Gold(I) complexes bearing N-heterocyclic carbenes (NHC) of the type (NHC)AuBr (3a/3b) [NHC = 1-methyl-3-benzylimidazol-2-ylidene (= MeBnIm), and 1,3-dibenzylimidazol-2-ylidene (= Bn(2)Im)] are prepared by transmetallation reactions of (tht)AuBr (tht = tetrahydrothiophene) and (NHC)AgBr (2a/2b). The homoleptic, ionic complexes [(NHC)(2)Au]Br (6a/6b) are synthesized by the reaction with free carbene. Successive oxidation of 3a/3b and 6a/6b with bromine gave the respective (NHC)AuBr(3) (4a/4b) and [(NHC)(2)AuBr(2)]Br (7a/7b) in good overall yields as yellow powders. All complexes were characterized by NMR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction. Reactions of the Au(III) complexes towards anionic ligands like carboxylates, phenolates and thiophenolates were investigated and result in a complete or partial reduction to a Au(I) complex. Irradiation of the Au(III) complexes with UV light yield the Au(I) congeners in a clean photo-reaction.

  10. IgE and IgG cross-reactivity among Lol p I and Lol p II/III. Identification of the C-termini of Lol p I, II, and III as cross-reactive structures.

    PubMed

    van Ree, R; van Leeuwen, W A; van den Berg, M; Weller, H H; Aalberse, R C

    1994-04-01

    In this study, the homologous C-termini of Lol p I, Lol p II, and Lol p III were shown to contain cross-reactive B-cell epitopes. This was demonstrated by inhibition studies with purified Lol p I, II, and III and synthetic peptides of their C-termini. It was ruled out that the observed cross-reactivity was caused by cross-contamination of the purified allergens. Both human IgE and IgG bound to the C-terminus of Lol p I. These antibodies were cross-reactive with Lol p II and, more specifically, with its C-terminus. Within a small panel of allergic patients, no cross-reactivity with Lol p III was found. A hyperimmune polyclonal rabbit antiserum against Lol p I also recognized the Lol p I C-terminus. As for human antibodies, cross-reactivity with Lol p II and its C-terminus was demonstrated. Cross-reactivity with Lol p III was demonstrated with C-terminal peptides, but not with native Lol p III. A polyclonal rabbit antiserum against Lol p II bound to the C-terminal peptides of both Lol p II and III. This binding was inhibited with Lol p I, confirming that cross-reactive structures exist not only on the C-termini of Lol p II and Lol p I, but also of Lol p III and Lol p I. The existence of cross-reactivity between Lol p I and Lol p II and III possibly contributes to the frequently observed cosensitization for these allergens in grass-pollen-allergic patients.

  11. Strain properties analysis and wireless collection system of PVDF for structural local health monitoring of civil engineering structures

    NASA Astrophysics Data System (ADS)

    Yu, Yan; Wang, Yang; Dong, Weijie; Jin, Yajing; Ou, Jinping

    2009-07-01

    For large civil engineering structures and base establishments, for example, bridges, super-high buildings, long-span space structures, offshore platforms and pipe systems of water & gas supply, their lives are up to a few decades or centuries. Damaged by environmental loads, fatigue effects, corrosion effects and material aging, these structures experience inevitably such side effects as damage accumulation, resistance reduction and even accidents. The traditional civil structure is a kind of passive one, whose performance and status are unpredictable to a great extent, but the informatics' introduction breaks a new path to obtain the status of the structure, thus it is an important research direction to evaluate and improve reliability of civil structures by the use of monitoring and health diagnosis technique, and this also assures the security of service for civil engineering structures. Smart material structure, originated from the aerospace sector, has been a research hotspot in civil engineering, medicine, shipping, and so on. For structural health monitoring of civil engineering, the research about high-performance sensing unit of smart material structure is very important, and this will possibly push further the development and application of monitoring and health diagnosis techniques. At present, piezoelectric materials are one of the most widely used sensing materials among the research of smart material structures. As one of the piezoelectric materials, PVDF(Polyvinylidene Fluoride)film is widely considered for the advantages of low cost, good mechanical ability, high sensibility, the ability of being easily placed and resistance of corrosion. However, only a few studies exit about building a mature monitoring system using PVDF. In this paper, for the sake of using PVDF for sensing unit for structural local monitoring of civil engineering, the strain sensing properties of PVDF are studied in detail. Firstly, the operating mechanism of PVDF is analyzed

  12. Aligned poly(L-lactic-co-e-caprolactone) electrospun microfibers and knitted structure: a novel composite scaffold for ligament tissue engineering.

    PubMed

    Vaquette, Cédryck; Kahn, Cyril; Frochot, Céline; Nouvel, Cécile; Six, Jean-Luc; De Isla, Natalia; Luo, Li-Hua; Cooper-White, Justin; Rahouadj, Rachid; Wang, Xiong

    2010-09-15

    We developed a novel technique involving knitting and electrospinning to fabricate a composite scaffold for ligament tissue engineering. Knitted structures were coated with poly(L-lactic-co-e-caprolactone) (PLCL) and then placed onto a rotating cylinder and a PLCL solution was electrospun onto the structure. Highly aligned 2-microm-diameter microfibers covered the space between the stitches and adhered to the knitted scaffolds. The stress-strain tensile curves exhibited an initial toe region similar to the tensile behavior of ligaments. Composite scaffolds had an elastic modulus (150 +/- 14 MPa) similar to the modulus of human ligaments. Biological evaluation showed that cells proliferated on the composite scaffolds and they spontaneously orientated along the direction of microfiber alignment. The microfiber architecture also induced a high level of extracellular matrix secretion, which was characterized by immunostaining. We found that cells produced collagen type I and type III, two main components found in ligaments. After 14 days of culture, collagen type III started to form a fibrous network. We fabricated a composite scaffold having the mechanical properties of the knitted structure and the morphological properties of the aligned microfibers. It is difficult to seed a highly macroporous structure with cells, however the technique we developed enabled an easy cell seeding due to presence of the microfiber layer. Therefore, these scaffolds presented attractive properties for a future use in bioreactors for ligament tissue engineering.

  13. Finite Element Model Optimization of the FalconSAT-5 Structural Engineering Model

    DTIC Science & Technology

    2009-03-01

    low-level sine sweep was performed to measure structural natural frequencies. Random vibration and sine burst tests were performed to validate the...3 FE Model Results . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.8 SEM I Vibrometer Test ...29 2.9 SEM II Shaker Vibration Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 III. Method

  14. The influence of particle size and structure on the sorption and oxidation behavior of birnessite: I. Adsorption of As(V) and oxidation of As(III)

    NASA Astrophysics Data System (ADS)

    Villalobos, Mario; Escobar-Quiroz, Ingrid N.; Salazar-Camacho, Carlos

    2014-01-01

    Sorption and oxidation reactions in the environment may affect substantially the mobility of redox-sensitive toxic trace elements and compounds. Investigating the environmental factors that influence these reactions is crucial in understanding and predicting the geochemical fate of these environmental species, as well as to design appropriate engineered remediation schemes. Arsenic is a widespread contaminant of concern, especially in its oxidized forms, and Mn oxide minerals are some of the major contributors to its oxidation. The goal of this work was to investigate the influence of particle size and structural differences of environmentally-relevant Mn(IV) birnessites on the adsorption of As(V) and on the oxidation of As(III). An acid birnessite of 39 m2/g and a δ-MnO2 of 114 m2/g were used. Both birnessites sorbed a maximum Pb(II) of 0.3 Pb/Mn, indicating a significantly larger layer cationic vacancy content for acid birnessite, and a density of reactive edge sites for both of 12 sites/nm2. As(V) forms a bidentate bridging complex on singly-coordinated surface sites at the birnessite particle edges regardless of loading, pH, birnessite type, and presence of pre-sorbed metals(II). Maximum As(V) adsorption, under repulsive electrostatic pH conditions did not yield adsorption congruency behavior between both birnessites at constant pH, presumably because the increase in internal vacancy content causes negative electrostatic repulsion towards external As(V) oxyanion binding. At pH 4.5 As(III) oxidation on birnessites was fast and quantitative at As/Mn ratios of 0.3-0.33, the reaction being largely driven by the proton concentration. At pH 6 δ-MnO2 oxidized As(III) faster and to a higher extent than acid birnessite, at equal masses; but the reverse at equal total surface areas. The oxidation driving force (independently from protons) was higher at pH 6 than at pH 4.5 because of Mn(II) product removal by sorption to interlayer vacancies, which overcomes reactive

  15. The Structures of Coiled-Coil Domains from Type III Secretion System Translocators Reveal Homology to Pore-Forming Toxins

    SciTech Connect

    Barta, Michael L.; Dickenson, Nicholas E.; Patil, Mrinalini; Keightley, Andrew; Wyckoff, Gerald J.; Picking, William D.; Picking, Wendy L.; Geisbrecht, Brian V.

    2012-03-26

    Many pathogenic Gram-negative bacteria utilize type III secretion systems (T3SSs) to alter the normal functions of target cells. Shigella flexneri uses its T3SS to invade human intestinal cells to cause bacillary dysentery (shigellosis) that is responsible for over one million deaths per year. The Shigella type III secretion apparatus is composed of a basal body spanning both bacterial membranes and an exposed oligomeric needle. Host altering effectors are secreted through this energized unidirectional conduit to promote bacterial invasion. The active needle tip complex of S. flexneri is composed of a tip protein, IpaD, and two pore-forming translocators, IpaB and IpaC. While the atomic structure of IpaD has been elucidated and studied, structural data on the hydrophobic translocators from the T3SS family remain elusive. We present here the crystal structures of a protease-stable fragment identified within the N-terminal regions of IpaB from S. flexneri and SipB from Salmonella enterica serovar Typhimurium determined at 2.1 {angstrom} and 2.8 {angstrom} limiting resolution, respectively. These newly identified domains are composed of extended-length (114 {angstrom} in IpaB and 71 {angstrom} in SipB) coiled-coil motifs that display a high degree of structural homology to one another despite the fact that they share only 21% sequence identity. Further structural comparisons also reveal substantial similarity to the coiled-coil regions of pore-forming proteins from other Gram-negative pathogens, notably, colicin Ia. This suggests that these mechanistically separate and functionally distinct membrane-targeting proteins may have diverged from a common ancestor during the course of pathogen-specific evolutionary events.

  16. III-V semiconductor Quantum Well systems: Physics of Gallium Arsenide two-dimensional hole systems and engineering of mid-infrared Quantum Cascade lasers

    NASA Astrophysics Data System (ADS)

    Chiu, YenTing

    This dissertation examines two types of III-V semiconductor quantum well systems: two-dimensional holes in GaAs, and mid-infrared Quantum Cascade lasers. GaAs holes have a much reduced hyperfine interaction with the nuclei due to the p-like orbital, resulting in a longer hole spin coherence time comparing to the electron spin coherence time. Therefore, holes' spins are promising candidates for quantum computing qubits, but the effective mass and the Lande g-factor, whose product determines the spin-susceptibility of holes, are not well known. In this thesis, we measure the effective hole mass through analyzing the temperature dependence of Shubnikov-de Haas oscillations in a relatively strong interacting two-dimensional hole systems confined to a 20 nm-wide, (311)A GaAs quantum well. The holes in this system occupy two nearly-degenerate spin subbands whose effective mass we measure to be ˜ 0.2 me. We then apply a sufficiently strong parallel magnetic field to fully depopulate one of the spin subbands, and the spin susceptibility of the two-dimensional hole system is deduced from the depopulation field. We also confine holes in closely spaced bilayer GaAs quantum wells to study the interlayer tunneling spectrum as a function of interlayer bias and in-plane magnetic field, in hope of probing the hole's Fermi contour. Quantum Cascade lasers are one of the major mid-infrared light sources well suited for applications in health and environmental sensing. One of the important factors that affect Quantum Cascade laser performance is the quality of the interfaces between the epitaxial layers. What has long been neglected is that interface roughness causes intersubband scattering, and thus affecting the relation between the lifetimes of the upper and lower laser states, which determines if population inversion is possible. We first utilize strategically added interface roughness in the laser design to engineer the intersubband scattering lifetimes. We further

  17. Solution structures of cyclosporin a and its complex with dysprosium(III) in SDS micelles: NMR and molecular dynamics studies.

    PubMed

    Bernardi, Francesca; D'Amelio, Nicola; Gaggelli, Elena; Molteni, Elena; Valensin, Gianni

    2008-01-24

    Cyclosporin A (CsA) is a cyclic naturally occurring peptide used to prevent graft rejection in organ transplantations. Its immunosuppressive activity is due to the formation of a complex with cyclophilin A (Cyp), in which the cis 9MeLeu-10MeLeu amide bond of CsA assumes a trans conformation. The mechanism of the conformational inversion has not been delineated, but it has been postulated that metal ions binding induces a conformational change that enables CsA to bind Cyp. In this work, we solved the structures of CsA in sodium dodecyl sulfate (SDS) micelles (which enhance its solubility and mimic the hydrophobic environment clinically used for drug delivery) and its complex with Dy(III) ion, whose coordination chemistry is frequently used to reproduce the effect of Ca(II). The paramagnetic properties of Dy(III) allowed us to build up a structure using proton relaxation enhancements, which remains stable in a MD simulation in the micelle environment.

  18. The Effect of the Secondary Structure on Dissociation of Peptide Radical Cations: Fragmentation of Angiotensin III and Its Analogues

    SciTech Connect

    Yang, Zhibo; Lam, Corey; Chu, Ivan K.; Laskin, Julia

    2008-09-28

    Fragmentation of protonated RVYIHPF and RVYIHPF-OMe and the corresponding radical cations was studied using time- and collision energy-resolved surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) specially equipped to perform SID experiments. Peptide radical cations were produced by gas-phase fragmentation of CoIII(salen)-peptide complexes. Both the energetics and mechanisms of dissociation of even-electron and odd-electron angiotensin III ions are quite different. Protonated molecules are much more stable towards fragmentation than the corresponding radical cations. RRKM modeling of the experimental data suggests that this stability is largely attributed to differences in threshold energies for dissociation while activation entropies are very similar. Detailed analysis of the experimental data obtained for radical cations demonstrated the presence of two distinct structures separated by a high free-energy barrier. The two families of structures were ascribed to the canonical and zwitterionic forms of the radical cations produced in our experiments.

  19. Crystal structure of the coordination polymer [FeIII 2{PtII(CN)4}3

    PubMed Central

    Seredyuk, Maksym; Muñoz, M. Carmen; Real, José A.; Iskenderov, Turganbay S.

    2015-01-01

    The title complex, poly[dodeca-μ-cyanido-diiron(III)triplat­inum(II)], [FeIII 2{PtII(CN)4}3], has a three-dimensional polymeric structure. It is built-up from square-planar [PtII(CN)4]2− anions (point group symmetry 2/m) bridging cationic [FeIIIPtII(CN)4]+ ∞ layers extending in the bc plane. The FeII atoms of the layers are located on inversion centres and exhibit an octa­hedral coordination sphere defined by six N atoms of cyanide ligands, while the PtII atoms are located on twofold rotation axes and are surrounded by four C atoms of the cyanide ligands in a square-planar coordination. The geometrical preferences of the two cations for octa­hedral and square-planar coordination, respectively, lead to a corrugated organisation of the layers. The distance between neighbouring [FeIIIPtII(CN)4]+ ∞ layers corresponds to the length a/2 = 8.0070 (3) Å, and the separation between two neighbouring PtII atoms of the bridging [PtII(CN)4]2− groups corresponds to the length of the c axis [7.5720 (2) Å]. The structure is porous with accessible voids of 390 Å3 per unit cell. PMID:25705468

  20. Fe(II) sorption on pyrophyllite: Effect of structural Fe(III) (impurity) in pyrophyllite on nature of layered double hydroxide (LDH) secondary mineral formation

    SciTech Connect

    Starcher, Autumn N.; Li, Wei; Kukkadapu, Ravi K.; Elzinga, Evert J.; Sparks, Donald L.

    2016-11-01

    Fe(II)-Al(III)-LDH (layered double hydroxide) phases have been shown to form from reactions of aqueous Fe(II) with Fe-free Al-bearing minerals (phyllosilicate/clays and Al-oxides). To our knowledge, the effect of small amounts of structural Fe(III) impurities in “neutral” clays on such reactions, however, were not studied. In this study to understand the role of structural Fe(III) impurity in clays, laboratory batch studies with pyrophyllite (10 g/L), an Al-bearing phyllosilicate, containing small amounts of structural Fe(III) impurities and 0.8 mM and 3 mM Fe(II) (both natural and enriched in 57Fe) were carried out at pH 7.5 under anaerobic conditions (4% H2 – 96% N2 atmosphere). Samples were taken up to 4 weeks for analysis by Fe-X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy. In addition to the precipitation of Fe(II)-Al(III)-LDH phases as observed in earlier studies with pure minerals (no Fe(III) impurities in the minerals), the analyses indicated formation of small amounts of Fe(III) containing solid(s), most probably hybrid a Fe(II)-Al(III)/Fe(III)-LDH phase. The mechanism of Fe(II) oxidation was not apparent but most likely was due to interfacial electron transfer from the sorbed Fe(II) to the structural Fe(III) and/or surface-sorption-induced electron-transfer from the sorbed Fe(II) to the clay lattice. Increase in the Fe(II)/Al ratio of the LDH with reaction time further indicated the complex nature of the samples. This research provides evidence for the formation of both Fe(II)-Al(III)-LDH and Fe(II)-Fe(III)/Al(III)-LDH-like phases during reactions of Fe(II) in systems that mimic the natural environments. Better understanding Fe phase formation in complex laboratory studies will improve models of natural redox systems.

  1. Structure of the cauliflower mosaic virus genome. III. Restriction endonuclease mapping of thirty-three isolates.

    PubMed

    Hull, R

    1980-01-15

    The sites of various restriction endonucleases were mapped on the DNA of cauliflower mosaic virus isolate Cabb B-JI.FspAI,HgiAI,HhaI, andXhoI each cut at one site,PstI andPvuII each at two sites,BglII at five sites, andHindIII at nine sites;SacP,SmaI, andXbaI did not cut this DNA. These sites and those ofBamHI,EcoRI, andSalGI were compared with the sites of these enzymes on the DNAs of 32 other CaMV isolates. Considerable variations were found both in numbers and map positions of the sites of the restriction enzymes. The significance of this variation is discussed.

  2. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide.

    PubMed

    Kharchenko, Valerii I; Kurbatov, Ilya A; Cherednichenko, Alexander I; Mirochnik, Anatoly G; Zhikhareva, Polina A

    2017-03-05

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb(3+) ion (transitions (5)D4→(7)FJ, J=3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  3. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide

    NASA Astrophysics Data System (ADS)

    Kharchenko, Valerii I.; Kurbatov, Ilya A.; Cherednichenko, Alexander I.; Mirochnik, Anatoly G.; Zhikhareva, Polina A.

    2017-03-01

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb3 + ion (transitions 5D4 → 7FJ, J = 3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  4. Photoluminescence changes of III-Nitride lateral polarity structures after chemical functionalization

    NASA Astrophysics Data System (ADS)

    Berg, Nora G.; Franke, Alexander; Kirste, Ronny; Collazo, Ramon; Ivanisevic, Albena

    2016-12-01

    The photoluminescence changes of a III-Nitride semiconductor with various surface topographies were studied after chemical functionalization. Al x Ga1-x N with a composition of 70% aluminum was used and the surfaces were functionalized with a fluorophore dye-terminated peptide using a linker molecule. The stability of the wafers in water was studied using inductively coupled plasma mass spectrometry prior to modifying the material. The leaching data demonstrated that the AlGaN material in highly stable in biological conditions over 7 d. The attachment of the dye to the wafer was investigated using x-ray photoelectron spectroscopy and photoluminescence spectroscopy (PL). The PL spectrum showed a clear signature of the dye with a pronounced emission peak at approximately 260 nm, indicating a successful attachment to the surface.

  5. A Study on Aircraft Structure and Jet Engine

    NASA Astrophysics Data System (ADS)

    Park, Gil Moon; Park, Hwan Kyu; Kim, Jong Il; Kim, Jin Won; Kim, Jin Heung; Lee, Moo Seok; Chung, Nak Kyu

    1985-12-01

    The one of critical factor in gas turbine engine performance is high turbine inlet gas temperature. Therefore, the turbine rotor has so many problems which must be considered such as the turbine blade cooling, thermal stress of turbine disk due to severe temperature gradient, turbine rotor tip clearance, under the high operation temperature. The purpose of this study is to provide the temperature distribution and heat flux in turbine disk which is required to considered premensioned problem by the Finite Difference Method and the Finite Element Methods on the steady state condition.

  6. Bismuth-induced surface structure and morphology in III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Duzik, Adam J.

    2015-04-01

    Bi is the largest group V element and has a number of advantages in III-V semiconductor properties, such as bandgap reduction, spin-orbit coupling, a preserved electron mobility over III-V-N materials, and nearly ideal surfactant properties resulting in a surface smoothing effect on GaAs. However, the mechanism for this behavior is not well understood. Insight on the mechanism is obtained through study of the Bi-terminated GaAs surface morphology and atomic reconstructions produced via molecular beam epitaxy (MBE). Experimental scanning tunneling microscopy (STM) characterization of the Bi/GaAs surface reveal disordered (1x3), (2x3), and (4x3) reconstructions, often sharing the same reflective high-energy electron diffraction (RHEED) patterns. Roughness on the micron length scale decreases as the step widen, attributed to the concurrent increase of opposite direction step edges on the nanometer length scale. Corresponding cluster expansion, density functional theory (DFT), and Monte Carlo simulations all point to the stability of the disordered (4x3) reconstruction at finite temperature as observed in experimental STM. The effects of incorporated Bi are determined through epitaxial GaSbBi growth on GaSb with various Ga:Sb:Bi flux ratios. Biphasic surface droplets are observed with sub-droplets, facets, and substrate etching. Despite the rough growth front, X-ray diffraction (XRD) and Rutherford backscatter (RBS) measurements show significant Bi incorporation of up to 12% into GaSb, along with a concurrent increase of background As concentration. This is attributed to a strain auto-compensation effect. Bi incorporation of up to 10% is observed for the highest Bi fluxes while maintaining low surface droplet density.

  7. Synthesis, structure, and spectral and electrochemical properties of chromium(III) tris-(8-hydroxyquinolinate).

    PubMed

    Freitas, Ana R; Silva, Mónica; Ramos, M Luísa; Justino, Licínia L G; Fonseca, Sofia M; Barsan, Madalina M; Brett, Christopher M A; Silva, M Ramos; Burrows, Hugh D

    2015-07-07

    The kinetically inert chromium(III) tris-(8-hydroxyquinolinate), Crq3, has been synthesized, crystallized from 90% methanol-water, and characterized by MALDI-TOF mass spectrometry, thermogravimetry, FTIR, NMR spectroscopy, and X-ray powder diffraction. It is formed as a methanol solvate, but the solvent can be removed by heating. Large paramagnetic shifts and spectral broadening in (1)H NMR spectra indicate electron delocalization between the metal and the ligand. DFT calculations show it is present as the meridional isomer, with the HOMO largely based on one of the metal 3d orbitals and the LUMO essentially localized on the ligands. Cyclic voltammetry (CV) in acetonitrile solutions shows four oxidation peaks and two, less intense reduction waves on the first scan. The HOMO energy determined from the first oxidation peak is fairly close to that obtained by DFT, in agreement with this being mainly metal based. Although the number of peaks decreases on subsequent CV scans, the complex shows markedly enhanced electrochemical stability compared with aluminium(III) tris-(8-hydroxyquinolinate). Solution UV/visible absorption and solid diffuse reflectance spectra have a weak, long wavelength band, assigned to the metal based d-d transition, in addition to the normal, ligand based bands seen in metal quinolates. The energy of the lowest energy band is identical to the HOMO-LUMO separation obtained by cyclic voltammetry, in agreement with the above description. The compound is only weakly luminescent, in contrast to many other metal quinolates, due to the lowest energy transition being metal rather than ligand based. The potential of this compound as an electron transporting/hole blocking layer in optoelectronic devices is indicated.

  8. Detailed Post-Soft Impact Progressive Damage Assessment for Hybrid Structure Jet Engines

    NASA Technical Reports Server (NTRS)

    Siddens, Aaron; Bayandor, Javid; Celestina, Mark L.

    2014-01-01

    Currently, certification of engine designs for resistance to bird strike is reliant on physical tests. Predictive modeling of engine structural damage has mostly been limited to evaluation of individual forward section components, such as fan blades within a fixed frame of reference, to direct impact with a bird. Such models must be extended to include interactions among engine components under operating conditions to evaluate the full extent of engine damage. This paper presents the results of a study aim to develop a methodology for evaluating bird strike damage in advanced propulsion systems incorporating hybrid composite/metal structures. The initial degradation and failure of individual fan blades struck by a bird were investigated. Subsequent damage to other fan blades and engine components due to resultant violent fan assembly vibrations and fragmentation was further evaluated. Various modeling parameters for the bird and engine components were investigated to determine guidelines for accurately capturing initial damage and progressive failure of engine components. Then, a novel hybrid structure modeling approach was investigated and incorporated into the crashworthiness methodology. Such a tool is invaluable to the process of design, development, and certification of future advanced propulsion systems.

  9. Immobilization of cobalt(III) Schiff base complexes onto Montmorillonite-K10: Synthesis, experimental and theoretical structural determination.

    PubMed

    Kianfar, Ali Hossein; Kamil Mahmood, Wan Ahmad; Dinari, Mohammad; Farrokhpour, Hossein; Enteshari, Majid; Azarian, Mohammad Hossein

    2015-02-05

    The [Co(naphophen)(PPh3)(OH2)]ClO4 and [Co(naphophen)(PBu3)(OH2)]BF4 (where naphophen=bis(naphthaldehyde)1,2-phenylenediimine) complexes were synthesized and chracterized by FT-IR, UV-Vis, (1)H NMR, (13)C NMR spectroscopy and elemental analysis techniques. The coordination geometry of the synthesized complexes were determined by X-ray crystallography. Cobalt (III) complexes have six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base forms the equatorial plane. These complexes showed a dimeric structure via hydrogen bonding between the phenolate oxygen and the hydrogens of the coordinated H2O molecule. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The synthesized complexes were incorporated onto the Montmorillonite-K10 nanoclay via simple ion-exchange reaction. The structure and morphology of the obtained nanohybrids were identified by FT-IR, XRD, TGA/DTA, SEM and TEM techniques. Based on the XRD results of the new nanohybrid materials, the Schiff base complexes were intercalated in the interlayer spaces of clay. SEM and TEM micrographs of the clay/complex shows that the resulting hybrid nanomaterials has layer structures.

  10. Immobilization of cobalt(III) Schiff base complexes onto Montmorillonite-K10: Synthesis, experimental and theoretical structural determination

    NASA Astrophysics Data System (ADS)

    Kianfar, Ali Hossein; Kamil Mahmood, Wan Ahmad; Dinari, Mohammad; Farrokhpour, Hossein; Enteshari, Majid; Azarian, Mohammad Hossein

    2015-02-01

    The [Co(naphophen)(PPh3)(OH2)]ClO4 and [Co(naphophen)(PBu3)(OH2)]BF4 (where naphophen = bis(naphthaldehyde)1,2-phenylenediimine) complexes were synthesized and chracterized by FT-IR, UV-Vis, 1H NMR, 13C NMR spectroscopy and elemental analysis techniques. The coordination geometry of the synthesized complexes were determined by X-ray crystallography. Cobalt (III) complexes have six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base forms the equatorial plane. These complexes showed a dimeric structure via hydrogen bonding between the phenolate oxygen and the hydrogens of the coordinated H2O molecule. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The synthesized complexes were incorporated onto the Montmorillonite-K10 nanoclay via simple ion-exchange reaction. The structure and morphology of the obtained nanohybrids were identified by FT-IR, XRD, TGA/DTA, SEM and TEM techniques. Based on the XRD results of the new nanohybrid materials, the Schiff base complexes were intercalated in the interlayer spaces of clay. SEM and TEM micrographs of the clay/complex shows that the resulting hybrid nanomaterials has layer structures.

  11. Engineering structure and function using thermo-responsive biopolymers

    PubMed Central

    Pastuszka, Martha K.

    2015-01-01

    Self-assembly enables exquisite control at the smallest scale and generates order amongst macromolecular building blocks that remain too small to be manipulated individually. Environmental cues, such as heating, can trigger the organization of these materials from individual molecules to multiparticle assemblies with a variety of compositions and functions. Synthetic as well as biological polymers have been engineered for these purposes; however, biological strategies can offer unparalleled control over the composition of these macromolecular building blocks. Biologic polymers are macromolecules, themselves composed of monomeric units that can be precisely tailored at the genetic level; furthermore, they can often utilize endogenous biodegradation pathways, which may enhance their potential clinical applications. DNA (nucleotides), polysaccharides (carbohydrates), and proteins (amino acids) have all been engineered to self-assemble into nanostructures in response to a change in temperature. This focus article reviews the growing body of literature exploring temperature-dependent nano-assembly of these biological macromolecules, summarizes some of their physical properties, and discusses future directions. PMID:26112277

  12. Introducing Students to Structural Dynamics and Earthquake Engineering

    ERIC Educational Resources Information Center

    Anthoine, Armelle; Marazzi, Francesco; Tirelli, Daniel

    2010-01-01

    The European Laboratory for Structural Assessment (ELSA) is one of the world's main laboratories for seismic studies. Besides its research activities, it also aims to bring applied science closer to the public. This article describes teaching activities based on a demonstration shaking table which is used to introduce the structural dynamics of…

  13. Fluorescent naphthalene diols as bridging ligands in Ln(III) cluster chemistry: synthetic, structural, magnetic, and photophysical characterization of Ln(III)8 "Christmas stars".

    PubMed

    Alexandropoulos, Dimitris I; Fournet, Adeline; Cunha-Silva, Luís; Mowson, Andrew M; Bekiari, Vlasoula; Christou, George; Stamatatos, Theocharis C

    2014-06-02

    The initial employment of the fluorescent bridging ligand naphthalene-2,3-diol in 4f-metal coordination chemistry has provided access to a new family of Ln(III)8 clusters with a "Christmas-star" topology, single-molecule magnetism behavior, and ligand-centered emissions.

  14. Computer applications for engineering/structural analysis. Revision 1

    SciTech Connect

    Zaslawsky, M.; Samaddar, S.K.

    1991-12-31

    Analysts and organizations have a tendency to lock themselves into specific codes with the obvious consequences of not addressing the real problem and thus reaching the wrong conclusion. This paper discusses the role of the analyst in selecting computer codes. The participation and support of a computation division in modifying the source program, configuration management, and pre- and post-processing of codes are among the subjects discussed. Specific examples illustrating the computer code selection process are described in the following problem areas: soil structure interaction, structural analysis of nuclear reactors, analysis of waste tanks where fluid structure interaction is important, analysis of equipment, structure-structure interaction, analysis of the operation of the superconductor supercollider which includes friction and transient temperature, and 3D analysis of the 10-meter telescope being built in Hawaii. Validation and verification of computer codes and their impact on the selection process are also discussed.

  15. Engineering Virus Capsids Into Biomedical Delivery Vehicles: Structural Engineering Problems in Nanoscale.

    PubMed

    Bajaj, Saumya; Banerjee, Manidipa

    2015-01-01

    Virus capsids have evolved to protect the genome sequestered in their interior from harsh environmental conditions, and to deliver it safely and precisely to the host cell of choice. This characteristic makes them naturally perfect containers for delivering therapeutic molecules to specific locations. Development of an ideal virus-based nano-container for medical usage requires that the capsid be converted into a targetable protein cage which retains the original stability, flexibility and host cell penetrating properties of the native particles, without the associated immunogenicity, and is able to encapsulate large quantities of therapeutic or diagnostic material. In the last few years, several icosahedral, non-enveloped viruses, with a diameter of 25-90 nm-a size which conveniently falls within the 10-100 nm range desirable for biomedical nanoparticles-have been chemically or genetically engineered towards partial fulfilment of the above criteria. This review summarizes the approaches taken towards engineering viruses into biomedical delivery devices and discusses the challenges involved in achieving this goal.

  16. Two-dimensional 3d-4f heterometallic coordination polymers: syntheses, crystal structures, and magnetic properties of six new Co(II)-Ln(III) compounds.

    PubMed

    Díaz-Gallifa, Pau; Fabelo, Oscar; Pasán, Jorge; Cañadillas-Delgado, Laura; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2014-06-16

    Six new heterometallic cobalt(II)-lanthanide(III) complexes of formulas [Ln(bta)(H2O)2]2[Co(H2O)6]·10H2O [Ln = Nd(III) (1) and Eu(III) (2)] and [Ln2Co(bta)2(H2O)8]n·6nH2O [Ln = Eu(III) (3), Sm(III) (4), Gd(III) (5), and Tb(III) (6)] (H4bta = 1,2,4,5-benzenetretracaboxylic acid) have been synthesized and characterized via single-crystal X-ray diffraction. 1 and 2 are isostructural compounds with a structure composed of anionic layers of [Ln(bta)(H2O)2]n(n-) sandwiching mononuclear [Co(H2O)6](2+) cations plus crystallization water molecules, which are interlinked by electrostatic forces and hydrogen bonds, leading to a supramolecular three-dimensional network. 3-6 are also isostructural compounds, and their structure consists of neutral layers of formula [Ln2Co(bta)2(H2O)8]n and crystallization water molecules, which are connected through hydrogen bonds to afford a supramolecular three-dimensional network. Heterometallic chains formed by the regular alternation of two nine-coordinate lanthanide(III) polyhedra [Ln(III)O9] and one compressed cobalt(II) octahedron [Co(II)O6] along the crystallographic c-axis are cross-linked by bta ligands within each layer of 3-6. Magnetic susceptibility measurements on polycrystalline samples for 3-6 have been carried out in the temperature range of 2.0-300 K. The magnetic behavior of these types of Ln(III)-Co(II) complexes, which have been modeled by using matrix dagonalization techniques, reveals the lack of magnetic coupling for 3 and 4, and the occurrence of weak antiferromagnetic interactions within the Gd(III)-Gd(III) (5) and Tb(III)-Tb(III) (6) dinuclear units through the exchange pathway provided by the double oxo(carboxylate) and double syn-syn carboxylate bridges.

  17. RNA-Puzzles Round III: 3D RNA structure prediction of five riboswitches and one ribozyme.

    PubMed

    Miao, Zhichao; Adamiak, Ryszard W; Antczak, Maciej; Batey, Robert T; Becka, Alexander J; Biesiada, Marcin; Boniecki, Michał J; Bujnicki, Janusz; Chen, Shi-Jie; Cheng, Clarence Yu; Chou, Fang-Chieh; Ferré-D'Amaré, Adrian R; Das, Rhiju; Dawson, Wayne K; Feng, Ding; Dokholyan, Nikolay V; Dunin-Horkawicz, Stanisław; Geniesse, Caleb; Kappel, Kalli; Kladwang, Wipapat; Krokhotin, Andrey; Łach, Grzegorz E; Major, François; Mann, Thomas H; Magnus, Marcin; Pachulska-Wieczorek, Katarzyna; Patel, Dinshaw J; Piccirilli, Joseph A; Popenda, Mariusz; Purzycka, Katarzyna J; Ren, Aiming; Rice, Greggory M; Santalucia, John; Sarzynska, Joanna; Szachniuk, Marta; Tandon, Arpit; Trausch, Jeremiah J; Tian, Siqi; Wang, Jian; Weeks, Kevin M; Williams, Benfeard; Xiao, Yi; Xu, Xiaojun; Zhang, Dong; Zok, Tomasz; Westhof, Eric

    2017-01-30

    RNA-Puzzles is a collective experiment in blind 3D RNA structure prediction. We report here a third round of RNA-Puzzles. Five puzzles, 4, 8, 12, 13, 14, all structures of riboswitch aptamers and puzzle 7, a ribozyme structure, are included in this round of the experiment. The riboswitch structures include biological binding sites for small molecules (S-adenosyl methionine, cyclic diadenosine monophosphate, 5-amino 4-imidazole carboxamide riboside 5'-triphosphate, glutamine) and proteins (YbxF) and one set describes large conformational changes between ligand-free and ligand-bound states; the Varkud satellite ribozyme is the most recently solved structure of a known large ribozyme. All the puzzles have established biological functions and require structural understanding to appreciate their molecular mechanisms. Through the use of fast-track experimental data, including multidimensional chemical mapping, and accurate prediction of RNA secondary structure, a large portion of the contacts in 3D have been predicted correctly leading to similar topologies for the top ranking predictions. Template-based and homology-derived predictions could predict structures to particularly high accuracies. However, achieving biological insights from de novo prediction of RNA 3D structures still depends on the size and complexity of the RNA. Blind computational predictions of RNA structures already appear to provide useful structural information in many cases. Similar to the previous RNA-Puzzles Round II experiment, the prediction of non-Watson-Crick interactions and the observed high atomic clash scores reveal notable need for algorithm of improvement. All prediction models and assessment results are available at http://ahsoka.u-strasbg.fr/rnapuzzles/.

  18. Structure of the haemagglutinin-neuraminidase from human parainfluenza virus type III.

    PubMed

    Lawrence, Michael C; Borg, Natalie A; Streltsov, Victor A; Pilling, Patricia A; Epa, V Chandana; Varghese, Joseph N; McKimm-Breschkin, Jennifer L; Colman, Peter M

    2004-01-30

    The three-dimensional structure of the haemagglutinin-neuraminidase (HN) from a human parainfluenza virus is described at ca 2.0 A resolution, both in native form and in complex with three substrate analogues. In support of earlier work on the structure of the homologous protein from the avian pathogen Newcastle disease virus (NDV), we observe a dimer of beta-propellers and find no evidence for spatially separated sites performing the receptor-binding and neuraminidase functions of the protein. As with the NDV HN, the active site of the HN of parainfluenza viruses is structurally flexible, suggesting that it may be able to switch between a receptor-binding state and a catalytic state. However, in contrast to the NDV structures, we observe no ligand-induced structural changes that extend beyond the active site and modify the dimer interface.

  19. Engine structures modeling software system: Computer code. User's manual

    NASA Technical Reports Server (NTRS)

    1992-01-01

    ESMOSS is a specialized software system for the construction of geometric descriptive and discrete analytical models of engine parts, components and substructures which can be transferred to finite element analysis programs such as NASTRAN. The software architecture of ESMOSS is designed in modular form with a central executive module through which the user controls and directs the development of the analytical model. Modules consist of a geometric shape generator, a library of discretization procedures, interfacing modules to join both geometric and discrete models, a deck generator to produce input for NASTRAN and a 'recipe' processor which generates geometric models from parametric definitions. ESMOSS can be executed both in interactive and batch modes. Interactive mode is considered to be the default mode and that mode will be assumed in the discussion in this document unless stated otherwise.

  20. A hexaaza macrocyclic ligand containing acetohydrazide pendants for Ln(III) complexation in aqueous solution. Solid-state and solution structures and DFT calculations.

    PubMed

    Núñez, Cristina; Bastida, Rufina; Macías, Alejandro; Mato-Iglesias, Marta; Platas-Iglesias, Carlos; Valencia, Laura

    2008-08-07

    Lanthanide complexes of a hexaaza macrocyclic ligand containing acetohydrazide pendants (L) have been synthesised (Ln = La-Er, except Pm), and structural studies have been carried out both in the solid state and in aqueous solution. Attempts to isolate the complexes of the heaviest Ln(iii) ions (Ln = Tm-Lu) were unsuccessful. The crystal structures of the ligand and its lanthanum complex have been determined by single-crystal X-ray crystallography. The X-ray crystal structure of [La(L)](3+) shows the metal ion being ten-coordinate, with the acetohydrazide pendants situated alternatively above and below the plane of the macrocycle. The two five membered chelate rings formed by the ethylenediamine moieties adopt (deltadelta) [or (lambdalambda)] conformations. The [Ln(L)](3+) complexes have been characterised by means of density-functional theory (DFT) calculations (B3LYP model). The structures obtained from these theoretical calculations are in very good agreement with the experimental solution structures, as obtained from paramagnetic NMR measurements on the Ce(iii), Pr(III), Nd(III) and Eu(III) complexes. The complexes adopt in aqueous solution a D(2) structure with the ligand adopting a (deltadelta) [or (lambdalambda)] conformation.

  1. Mapping the effective mass of electrons in III-V semiconductor quantum confined structures

    NASA Astrophysics Data System (ADS)

    Gass, M. H.; Papworth, A. J.; Beanland, R.; Bullough, T. J.; Chalker, P. R.

    2006-01-01

    The electron effective mass me* can be calculated from the Kramers-Kronig transformation of electron energy loss spectra (EELS) for III-V semiconductor materials. The mapping capabilities of a scanning transmission electron microscope, equipped with a GatanEnfina™ EELS system are exploited to produce maps showing the variation of me* with nanometer scale resolution for a range of semiconductors. The analysis was carried out on three material systems: a GaInNAs quantum well in a GaAs matrix; InAs quantum dots in a GaAs matrix, and bulk wurzitic GaN. Values of me* were measured as ˜0.07m0 for GaAs and 0.183m0 for GaN, both in excellent agreement with the literature. It has also been shown that the high frequency dielectric constant can be calculated using the Kramers-Kronig methodology. When the high frequency dielectric constant is incorporated into the calculations a much more accurate visual representation of me* is displayed in the maps.

  2. Uranium dioxide in Fe(III)-containing ionic liquids with DMSO: Dissolution, separation, and structural characterization

    NASA Astrophysics Data System (ADS)

    Yao, Aining; Chu, Taiwei

    2016-11-01

    UO2 can be successfully dissolved in imidazolium-based Fe(III)-containing ionic liquids (ILs) with the help of DMSO. Spectroscopic studies and X-ray diffraction show that UO2Cl42- is the principal product. The dissolved uranyl species can be easily separated from the ILs via a combination of crystallization and solvent extraction. Moreover, even if 15.2 wt% of the rare-earth elements of Sm, Eu, and Gd, compared with the total amount of uranium and the rare-earth elements, exist in the IL, only uranium-containing crystals would be selectively formed and separated from the system. The solvents of acetone and acetonitrile could be used to separate the rare-earth elements from uranium in the IL with the help of imidazolium chloride. Considering the complete process from the dissolution of UO2 and some rare-earth oxides to the separation of uranium and rare-earth elements in the IL, the facile approach is promising for the spent nuclear fuel reprocessing.

  3. Synthesis and structure of new mononuclear octahedral cobalt(III) dioximates derived from isonicotinic hydrazide

    NASA Astrophysics Data System (ADS)

    Cocu, Maria; Bulhac, Ion; Coropceanu, Eduard; Melnic, Elena; Shova, Sergiu; Ciobanica, Olga; Gutium, Victoria; Bourosh, Paulina

    2014-04-01

    New organic ligand L (1) resulting from isonicotinic hydrazide and 2,4-pentanedione has been prepared and investigated by physicochemical methods, including elemental analysis, 1H and 13C NMR, IR spectroscopy and X-ray studies. The X-ray investigation revealed that the condensation of 2,4-pentanedione with isonicotinic hydrazide is accompanied by the formation of a five-membered ring including three carbon atoms of 2,4-pentanedione and two nitrogen atoms of the isonicotinic hydrazide fragment. The reaction between [Co(DfgH)2Br(H2O)] (DfgH2 = diphenylglyoxime) and L resulted in the formation of the mononuclear octahedral complex [Co(DfgH)2BrL] (2) with the substitution of the water molecule in the apical position by the ligand L. The reaction starting from [Co(DmgH)2Cl(H2O)] (DmgH = dimethylglyoxime) and L resulted in the mononuclear octahedral Co(III) complex with the composition [Co(DmgH)2ClL‧] (3), where L‧ unexpectedly represents a dehydrated derivative of L. The two coordination compounds are characterized by X-ray diffraction method. The IR, 1H NMR spectral studies of new compounds are also reported.

  4. Structural and Functional Characterization of the Bacterial Type III Secretion Export Apparatus

    PubMed Central

    Brunner, Matthias J.; Yan, Jun; Franz-Wachtel, Mirita; Schärfe, Charlotta; Grin, Iwan; Galán, Jorge E.; Macek, Boris; Marlovits, Thomas C.; Robinson, Carol V.

    2016-01-01

    Bacterial type III protein secretion systems inject effector proteins into eukaryotic host cells in order to promote survival and colonization of Gram-negative pathogens and symbionts. Secretion across the bacterial cell envelope and injection into host cells is facilitated by a so-called injectisome. Its small hydrophobic export apparatus components SpaP and SpaR were shown to nucleate assembly of the needle complex and to form the central “cup” substructure of a Salmonella Typhimurium secretion system. However, the in vivo placement of these components in the needle complex and their function during the secretion process remained poorly defined. Here we present evidence that a SpaP pentamer forms a 15 Å wide pore and provide a detailed map of SpaP interactions with the export apparatus components SpaQ, SpaR, and SpaS. We further refine the current view of export apparatus assembly, consolidate transmembrane topology models for SpaP and SpaR, and present intimate interactions of the periplasmic domains of SpaP and SpaR with the inner rod protein PrgJ, indicating how export apparatus and needle filament are connected to create a continuous conduit for substrate translocation. PMID:27977800

  5. Synthesis, structures and urease inhibitory activity of cobalt(III) complexes with Schiff bases.

    PubMed

    Jing, Changling; Wang, Cunfang; Yan, Kai; Zhao, Kedong; Sheng, Guihua; Qu, Dan; Niu, Fang; Zhu, Hailiang; You, Zhonglu

    2016-01-15

    A series of new cobalt(III) complexes were prepared. They are [CoL(1)(py)3]·NO3 (1), [CoL(2)(bipy)(N3)]·CH3OH (2), [CoL(3)(HL(3))(N3)]·NO3 (3), and [CoL(4)(MeOH)(N3)] (4), where L(1), L(2), L(3) and L(4) are the deprotonated form of N'-(2-hydroxy-5-methoxybenzylidene)-3-methylbenzohydrazide, N'-(2-hydroxybenzylidene)-3-hydroxylbenzohydrazide, 2-[(2-dimethylaminoethylimino)methyl]-4-methylphenol, and N,N'-bis(5-methylsalicylidene)-o-phenylenediamine, respectively, py is pyridine, and bipy is 2,2'-bipyridine. The complexes were characterized by infrared and UV-Vis spectra, and single crystal X-ray diffraction. The Co atoms in the complexes are in octahedral coordination. Complexes 1 and 4 show effective urease inhibitory activities, with IC50 values of 4.27 and 0.35 μmol L(-1), respectively. Complex 2 has medium activity against urease, with IC50 value of 68.7 μmol L(-1). While complex 3 has no activity against urease. Molecular docking study of the complexes with Helicobacter pylori urease was performed.

  6. Epitaxial growth of three dimensionally structured III-V photonic crystal via hydride vapor phase epitaxy

    SciTech Connect

    Zheng, Qiye; Kim, Honggyu; Zhang, Runyu; Zuo, Jianmin; Braun, Paul V.; Sardela, Mauro; Balaji, Manavaimaran; Lourdudoss, Sebastian; Sun, Yan-Ting

    2015-12-14

    Three-dimensional (3D) photonic crystals are one class of materials where epitaxy, and the resultant attractive electronic properties, would enable new functionalities for optoelectronic devices. Here we utilize self-assembled colloidal templates to fabricate epitaxially grown single crystal 3D mesostructured Ga{sub x}In{sub 1−x}P (GaInP) semiconductor photonic crystals using hydride vapor phase epitaxy (HVPE). The epitaxial relationship between the 3D GaInP and the substrate is preserved during the growth through the complex geometry of the template as confirmed by X-ray diffraction (XRD) and high resolution transmission electron microscopy. XRD reciprocal space mapping of the 3D epitaxial layer further demonstrates the film to be nearly fully relaxed with a negligible strain gradient. Fourier transform infrared spectroscopy reflection measurement indicates the optical properties of the photonic crystal which agree with finite difference time domain simulations. This work extends the scope of the very few known methods for the fabrication of epitaxial III-V 3D mesostructured materials to the well-developed HVPE technique.

  7. Structure of the SSB-DNA polymerase III interface and its role in DNA replication

    SciTech Connect

    Marceau, Aimee H; Bahng, Soon; Massoni, Shawn C; George, Nicholas P; Sandler, Steven J; Marians, Kenneth J; Keck, James L

    2012-05-22

    Interactions between single-stranded DNA-binding proteins (SSBs) and the DNA replication machinery are found in all organisms, but the roles of these contacts remain poorly defined. In Escherichia coli, SSB's association with the χ subunit of the DNA polymerase III holoenzyme has been proposed to confer stability to the replisome and to aid delivery of primers to the lagging-strand DNA polymerase. Here, the SSB-binding site on χ is identified crystallographically and biochemical and cellular studies delineate the consequences of destabilizing the χ/SSB interface. An essential role for the χ/SSB interaction in lagging-strand primer utilization is not supported. However, sequence changes in χ that block complex formation with SSB lead to salt-dependent uncoupling of leading- and lagging-strand DNA synthesis and to a surprising obstruction of the leading-strand DNA polymerase in vitro, pointing to roles for the χ/SSB complex in replisome establishment and maintenance. Destabilization of the χ/SSB complex in vivo produces cells with temperature-dependent cell cycle defects that appear to arise from replisome instability.

  8. Upgrading of existing structures. Phase III. Shelter design options. Final report

    SciTech Connect

    Tansley, R.S.; Gabrielsen, B.L.; Cuzner, G.J.

    1981-05-01

    This report presents the results of an investigation of blast upgrading of existing structures, which consisted of developing failure prediction methodologies for various structure types, both in as built and in upgraded configurations, and verifying these prediction techniques with full-scale load tests. These upgrading schemes were developed for use as shelters in support of Civil Defense crisis relocation planning. Structure types investigated included wood, steel, and concrete floor and roof systems. The results of this study are being used in the development of a shelter manual presenting the various upgrading concepts in an illustrative workbook form for use in the field.

  9. Isoform-specific monobody inhibitors of small ubiquitin-related modifiers engineered using structure-guided library design

    SciTech Connect

    Gilbreth, Ryan N.; Truong, Khue; Madu, Ikenna; Koide, Akiko; Wojcik, John B.; Li, Nan-Sheng; Piccirilli, Joseph A.; Chen, Yuan; Koide, Shohei

    2011-07-25

    Discriminating closely related molecules remains a major challenge in the engineering of binding proteins and inhibitors. Here we report the development of highly selective inhibitors of small ubiquitin-related modifier (SUMO) family proteins. SUMOylation is involved in the regulation of diverse cellular processes. Functional differences between two major SUMO isoforms in humans, SUMO1 and SUMO2/3, are thought to arise from distinct interactions mediated by each isoform with other proteins containing SUMO-interacting motifs (SIMs). However, the roles of such isoform-specific interactions are largely uncharacterized due in part to the difficulty in generating high-affinity, isoform-specific inhibitors of SUMO/SIM interactions. We first determined the crystal structure of a 'monobody,' a designed binding protein based on the fibronectin type III scaffold, bound to the yeast homolog of SUMO. This structure illustrated a mechanism by which monobodies bind to the highly conserved SIM-binding site while discriminating individual SUMO isoforms. Based on this structure, we designed a SUMO-targeted library from which we obtained monobodies that bound to the SIM-binding site of human SUMO1 with K{sub d} values of approximately 100 nM but bound to SUMO2 400 times more weakly. The monobodies inhibited SUMO1/SIM interactions and, unexpectedly, also inhibited SUMO1 conjugation. These high-affinity and isoform-specific inhibitors will enhance mechanistic and cellular investigations of SUMO biology.

  10. Quantum Chemical Study of the Fe(III)-Desferrioxamine B Siderophore Complex-Electronic Structure, Vibrational Frequencies, and Equilibrium Fe-Isotope Fractionation

    DTIC Science & Technology

    2008-09-19

    chemical study of the Fe(III)-desferrioxamine B siderophore complex—Electronic structure, vibrational frequencies, and equilibrium Fe-isotope fractionation...Fitzwater, 1988). Siderophores , an important class of organic acids with large complexation constants for Fe, are produced by sev- eral organisms in order...to overcome iron deficiencies (Wie- derhold et al., 2006). Due to their exceptionally high affinity for Fe, siderophores complex Fe(III) by extracting

  11. Fibre Bragg grating sensors for reinforcement corrosion monitoring in civil engineering structures

    NASA Astrophysics Data System (ADS)

    Grattan, S. K. T.; Basheer, P.; Taylor, S. E.; Zhao, W.; Sun, T.; Grattan, K. T. V.

    2007-07-01

    Fibre optic strain sensors offer a number of advantages over the current electrical resistance type gauges, yet are not widely used in civil engineering applications. The use of fibre optic strain sensors (with a cross comparison with the output of electrical resistance gauges) to monitor the production of corrosion by-products in civil engineering concrete structures containing reinforcement bars has been investigated and results reported.

  12. New Tools Being Developed for Engine- Airframe Blade-Out Structural Simulations

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles

    2003-01-01

    One of the primary concerns of aircraft structure designers is the accurate simulation of the blade-out event. This is required for the aircraft to pass Federal Aviation Administration (FAA) certification and to ensure that the aircraft is safe for operation. Typically, the most severe blade-out occurs when a first-stage fan blade in a high-bypass gas turbine engine is released. Structural loading results from both the impact of the blade onto the containment ring and the subsequent instantaneous unbalance of the rotating components. Reliable simulations of blade-out are required to ensure structural integrity during flight as well as to guarantee successful blade-out certification testing. The loads generated by these analyses are critical to the design teams for several components of the airplane structures including the engine, nacelle, strut, and wing, as well as the aircraft fuselage. Currently, a collection of simulation tools is used for aircraft structural design. Detailed high-fidelity simulation tools are used to capture the structural loads resulting from blade loss, and then these loads are used as input into an overall system model that includes complete structural models of both the engines and the airframe. The detailed simulation (shown in the figure) includes the time-dependent trajectory of the lost blade and its interactions with the containment structure, and the system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes are typically used, and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine s turbomachinery. To develop and validate these new tools with test data, the NASA Glenn Research Center has teamed with GE Aircraft Engines, Pratt & Whitney, Boeing Commercial Aircraft, Rolls-Royce, and MSC.Software.

  13. Polycyclic aromatic hydrocarbons in Australian coals. III. Structural elucidation by proton nuclear magnetic resonance spectroscopy

    SciTech Connect

    Chaffee, A.L.; Fookes, C.J.R.

    1988-01-01

    The molecular structures of a number of tetra- and pentacyclic aromatic hydrocarbons present in extracts of Victorian brown coal have been unambiguously established by /sup 1/H-NMR. The determined structures support the hypothesis that these polycyclic aromatic hydrocarbons (PAHs) are diagenetically derived from triterpenoid precursors based on the oleanane, ursane and lupane skeletons. The occurrence of diastereoisomerism in these PAHs has been revealed for the first time and the diastereomeric configurations of one pair of triaromatic compounds (XI and XII) defined.

  14. ORTEP-III: Oak Ridge Thermal Ellipsoid Plot Program for crystal structure illustrations

    SciTech Connect

    Burnett, M.N.; Johnson, C.K.

    1996-07-01

    This report describes a computer program for drawing crystal structure illustrations. Ball-and-stick type illustrations of a quality suitable for publication are produced with either spheres or thermal-motion probability ellipsoids on the atomic sites. The program can also produce stereoscopic pairs of illustrations which aid in the visualization of complex packing arrangements of atoms and thermal motion patterns. Interatomic distances, bond angles, and principal axes of thermal motion are also calculated to aid the structural study.

  15. Synthesis, molecular structure, theoretical calculation, DNA/protein interaction and cytotoxic activity of manganese(III) complex with 8-hydroxyquinoline.

    PubMed

    Thamilarasan, V; Sengottuvelan, N; Sudha, A; Srinivasan, P; Siva, A

    2015-01-01

    Manganese(III) complex (1) [Mn(8-hq)3] (where 8-hq=8-hydroxyquinoline) has been synthesized and characterized by elemental, spectral (UV-vis, FT-IR) and thermal analysis. The structure of complex (1) has been determined by single crystal X-ray diffraction studies and the configuration around manganese(III) ion was elongated octahedral coordination geometry. Density functional theory calculations were performed for ligand and its complex. Binding studies of ligand and complex 1 with calf thymus DNA (CT-DNA) was investigated by absorption, fluorescence, circular dichroic (CD) spectroscopy and viscosity measurements. Absorption spectral studies revealed that ligand and complex 1 binds to DNA groove and its intrinsic binding strength has been found to be 2.57×10(4) and 2.91×10(4)M(-1). A molecular docking study confirm that the complex 1 is a minor groove binder and was stabilized through hydrogen bonding interactions. Complex 1 exhibits a good binding propensity to bovine serum albumin (BSA) protein. The in vitro cytotoxicity study of complex 1 on breast cancer cell line (MCF-7) indicate that it has the potential to act as effective anticancer drug, with IC50 values of 3.25μM. The ligand and its complex have been screened for antimicrobial activities and the complex showed better antimicrobial activity than the free ligand.

  16. Enantiopure tetranuclear iron(III) complexes using chiral reduced Schiff base ligands: synthesis, structure, spectroscopy, magnetic properties, and DFT studies.

    PubMed

    Singh, Reena; Banerjee, Atanu; Colacio, Enrique; Rajak, Kajal Krishna

    2009-06-01

    Four new tetranuclear iron(III) complexes of formula [{Fe(L)(2)}(3)Fe], 1-4, have been prepared by reacting [Fe(ClO(4))(3)].6H(2)O with H(2)L in methanol. Here, L(2-) is the deprotonated form of N-(2-hyrdoxybenzyl)-l-valinol (H(2)L(1)), N-(2-hyrdoxybenzyl)-l-leucinol (H(2)L(2)), N-(5-chloro-2-hyrdoxybenzyl)-l-leucinol (H(2)L(3)), and N-(2-hyrdoxybenzyl)-l-phenylalaninol (H(2)L(4)). The complexes are prepared in an enantiomeric pure form. The complexes have been characterized with the help of IR, UV-vis, circular dichroism (CD), (1)H, and elemental analyses. The complex [{Fe(L(2))(2)}(3)Fe].CH(3)OH.2H(2)O, 2.CH(3)OH.2H(2)O, crystallizes in enantiomeric pure form containing a propeller-like Fe(4)O(6) core. (1)H and CD spectral studies of the four species are consistent with the structural similarities of the complexes in solution. Variable-temperature magnetic susceptibility of one case shows an intramolecular antiferromagnetic coupling between the Fe(III) ions. Magnetic measurements are in accord with the S = 5 ground state and suggest single molecular magnet behavior. The magnetic exchange coupling constant between the iron centers within the molecule is interpreted using broken-symmetry density functional theory calculation.

  17. Structural Health Monitoring on Turbine Engines Using Microwave Blade Tip Clearance Sensors

    NASA Technical Reports Server (NTRS)

    Woike, Mark; Abdul-Aziz, Ali; Clem, Michelle

    2014-01-01

    The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA) has taken a lead role in the investigation of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. As part of this effort, microwave sensor technology has been investigated as a means of making high temperature non-contact blade tip clearance, blade tip timing, and blade vibration measurements for use in gas turbine engines. This paper presents a summary of key results and findings obtained from the evaluation of two different types of microwave sensors that have been investigated for use possible in structural health monitoring applications. The first is a microwave blade tip clearance sensor that has been evaluated on a large scale Axial Vane Fan, a subscale Turbofan, and more recently on sub-scale turbine engine like disks. The second is a novel microwave based blade vibration sensor that was also used in parallel with the microwave blade tip clearance sensors on the experiments with the sub-scale turbine engine disks.

  18. Structural health monitoring on turbine engines using microwave blade tip clearance sensors

    NASA Astrophysics Data System (ADS)

    Woike, Mark; Abdul-Aziz, Ali; Clem, Michelle

    2014-04-01

    The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to the aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA) has taken a lead role in the investigation of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. As part of this effort, microwave sensor technology has been investigated as a means of making high temperature non-contact blade tip clearance, blade tip timing, and blade vibration measurements for use in gas turbine engines. This paper presents a summary of key results and findings obtained from the evaluation of two different types of microwave sensors that have been investigated for possible use in structural health monitoring applications. The first is a microwave blade tip clearance sensor that has been evaluated on a large scale Axial Vane Fan, a subscale Turbofan, and more recently on sub-scale turbine engine like disks. The second is a novel microwave based blade vibration sensor that was also used in parallel with the microwave blade tip clearance sensors on the same experiments with the sub-scale turbine engine disks.

  19. Structural, spectral, DFT, pH-metric and biological studies on Cr(III), Mn(II) and Fe(III) complexes of dithione heterocyclic thiosemicarbazide ligand

    NASA Astrophysics Data System (ADS)

    Abu El-Reash, Gaber M.; El-Gammal, Ola A.; El-Gamil, Mohammed M.

    2013-03-01

    Cr(III), Mn(II) and Fe(III) complexes derived from the quadruple potential dithione heterocyclic thiosemicarbazide ligand (H2PET) have been prepared and characterized by conventional techniques. The isolated complexes were assigned the formulae, [Cr(HPET)(H2O)2Cl2]·3H2O, [Mn(HPET)(H2O)Cl]2 and [Fe(HPET)(H2O)2Cl2]·H2O, respectively. IR data revealed that the ligand behaves as monobasic bidentate through (Cdbnd N)py and (Csbnd S) groups in both Cr(III) and Fe(III) complexes. In the binuclear Mn(II) complex, H2PET acts as NSNS monobasic tetradente via (Cdbnd N)py, (Csbnd S), (Cdbnd S) and the new azomethine, (Ndbnd C)* groups. An octahedral geometry for all complexes was proposed. The bond lengths, bond angles, HOMO, LUMO and dipole moment have been calculated by DFT using materials studio program to confirm the geometry of H2PET and its metal complexes. The ligand association constant and the stability constants of its complexes in addition to the thermodynamic parameters were calculated from pH metrically at 298, 308 and 318°K in 50% dioxane-water mixture, respectively. Also, the kinetic and thermodynamic parameters for the different thermal degradation steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. Moreover, the anti-oxidant (using ABTS and DPPH methods), anti-hemolytic, and cytotoxic activities of the compounds have been tested.

  20. Multiple piece turbine engine airfoil with a structural spar

    DOEpatents

    Vance, Steven J.

    2011-10-11

    A multiple piece turbine airfoil having an outer shell with an airfoil tip that is attached to a root with an internal structural spar is disclosed. The root may be formed from first and second sections that include an internal cavity configured to receive and secure the one or more components forming the generally elongated airfoil. The internal structural spar may be attached to an airfoil tip and place the generally elongated airfoil in compression. The configuration enables each component to be formed from different materials to reduce the cost of the materials and to optimize the choice of material for each component.

  1. Thunderstorm Peak Gust Estimation for Structural Engineering Design.

    NASA Astrophysics Data System (ADS)

    Akyuz, Fikri Adnan

    The statistical relationship between observed peak gust velocities and simultaneously measured fastest -minute wind was examined to determine "gust factors" appropriate to thunderstorm episodes in the Midwestern United States. The wind data from 1987 through 1991 for 81 National Weather Service (NWS) stations in 19 different states in the Midwest were extracted from the monthly and annual Local Climatological Data's (LCD's). Gust factor, linear regression and frequency analyses were the statistical analyses used in this study. Statistical analyses of the wind gusts and simultaneous one-minute wind data suggested that an average typical gust factor appropriate to thunderstorm episodes in the Midwestern United States is at least 1.5 (1.53 as a result of the gust factor analysis). It was also found in this research that 75% of the potentially damaging peak gusts in the range of 70 mph to 100 mph were associated with simultaneously measured sustained winds, averaged over 1 minute, of only 30 mph to 60 mph. The gust factor applicable to the design wind speed for the Midwestern United States, as published in American Society of Civil Engineers Standard, is, however, 1.25. Applying this gust factor to one minute winds in the range from 70 mph to 90 mph yields estimated 50-year peak gusts of 88 mph to 113 mph.

  2. Engineering Design Guidance for Detached Breakwaters as Shoreline Stabilization Structure

    DTIC Science & Technology

    1993-12-01

    Lakeview Park shoreline. Combinations of wave height, period, direction, and still-water levels were studied to determine test conditions that produced a...77 Structural Design Objectives ........................... 77 Design Wave and Water Level Selection .................... 77...Chesapeake Bay at Bay Ridge, Maryland ................... 9 Figure 8. Aerial view of Lakeview Park , Lorain, Ohio ......... 13 Figure 9. Detached

  3. Crystal structure engineering for improved performance of emerging nanoscale devices

    NASA Astrophysics Data System (ADS)

    Chimalgi, Vinay Uday

    Recent advances in growth techniques and increasing number of experimental studies have made nanostructures grown along different crystallographic directions a reality. These new structures could not only benefit the electronic devices used in mainstream information technology but also show great promise for applications in lasers, solid-state lighting, near-field photolithography, free-space quantum cryptography, consumer displays, quantum computation, as well as diagnostic medicine and imaging. However, only few theoretical investigations have been performed on these structures due to the complex nature of the interplay of atomicity, structural fields, polarization, and quantum size-quantization, all strong function of the crystallographic direction. The objective of this work is mainly four-fold: (1) Integrate a computational framework employing a combination of fully atomistic valence force-field molecular mechanics and 20-band sp3s*d5-SO tight-binding based electronic band­structure models, and numerically investigate the effects of internal fields on the electronic and optical properties of zincblende InAs/GaAs quantum dots grown on (100), (110), and (111) orientated substrates. (2) Augment/extend the open source NEMO 3-D bandstructure simulator by incorporating a recently proposed first principles based model to gauge the importance of nonlinear piezoelectricity on the single-particle electronic states and interband optical transitions in emerging In(Ga)N/GaN disk-in-wire LED structures having c-plane and m-plane wurtzite crystal symmetry. (3) Coupling the NEMO 3-D software toolkit with a commercial TCAD simulator to determine the terminal electrical and optical characteristics of InGaN/GaN disk-in-wire LEDs; and (4) Finding an optimum crystallographic device for InGaN/GaN disk-in-wire LEDs to achieve improved internal quantum efficiency (IQE).

  4. Fabrication-friendly subwavelength-structure-assisted waveguide for dispersion engineering.

    PubMed

    Jafari, Zeinab; Zarifkar, Abbas

    2016-11-10

    A subwavelength structure deposited on top of a silicon strip is utilized as a novel tool for dispersion engineering. The equivalent refractive index of the subwavelength structure can be tailored through adjusting its period and duty cycle. As finding suitable materials with both appropriate refractive index and fabrication compatibility is one of the main difficulties in dispersion engineering, the possibility of refractive index engineering is the most significant advantage of the proposed waveguide. It can be beneficial for controlling the properties of the fundamental quasi-TM mode and consequently its dispersion characteristics without any concern about material compatibility. Utilizing this waveguide geometry, a wide and flattened low-dispersion bandwidth can be achieved. Moreover, high anomalous and normal dispersion is realizable without any degradation in dispersion flatness over bandwidth. Therefore, the proposed waveguide structure is promising for dispersion tailoring in both linear and nonlinear applications.

  5. Structural characterization of poorly-crystalline scorodite, iron(III)-arsenate co-precipitates and uranium mill neutralized raffinate solids using X-ray absorption fine structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, N.; Jiang, D. T.; Cutler, J.; Kotzer, T.; Jia, Y. F.; Demopoulos, G. P.; Rowson, J. W.

    2009-06-01

    X-ray absorption fine structure (XAFS) is used to characterize the mineralogy of the iron(III)-arsenate(V) precipitates produced during the raffinate (aqueous effluent) neutralization process at the McClean Lake uranium mill in northern Saskatchewan, Canada. To facilitate the structural characterization of the precipitated solids derived from the neutralized raffinate, a set of reference compounds were synthesized and analyzed. The reference compounds include crystalline scorodite, poorly-crystalline scorodite, iron(III)-arsenate co-precipitates obtained under different pH conditions, and arsenate-adsorbed on goethite. The poorly-crystalline scorodite (prepared at pH 4 with Fe/As = 1) has similar As local structure as that of crystalline scorodite. Both As and Fe K-edge XAFS of poorly-crystalline scorodite yield consistent results on As-Fe (or Fe-As) shell. From As K-edge analysis the As-Fe shell has an inter-atomic distance of 3.33 ± 0.02 Å and coordination number of 3.2; while from Fe K-edge analysis the Fe-As distance and coordination number are 3.31 ± 0.02 Å and 3.8, respectively. These are in contrast with the typical arsenate adsorption on bidentate binuclear sites on goethite surfaces, where the As-Fe distance is 3.26 ± 0.03 Å and coordination number is close to 2. A similar local structure identified in the poorly-crystalline scorodite is also found in co-precipitation solids (Fe(III)/As(V) = 3) when precipitated at the same pH (pH = 4): As-Fe distance 3.30 ± 0.03 Å and coordination number 3.9; while at pH = 8 the co-precipitate has As-Fe distance of 3.27 ± 0.03 Å and coordination number about 2, resembling more closely the adsorption case. The As local structure in the two neutralized raffinate solid series (precipitated at pH values up to 7) closely resembles that in the poorly-crystalline scorodite. All of the raffinate solids have the same As-Fe inter-atomic distance as that in the poorly-crystalline scorodite, and a systematic decrease in the

  6. Factor Structure of the Norwegian Version of the WAIS-III in a Clinical Sample: The Arithmetic Problem

    ERIC Educational Resources Information Center

    Egeland, Jens; Bosnes, Ole; Johansen, Hans

    2009-01-01

    Confirmatory Factor Analyses (CFA) of the Wechsler Adult Intelligence Scale-III (WAIS-III) lend partial support to the four-factor model proposed in the test manual. However, the Arithmetic subtest has been especially difficult to allocate to one factor. Using the new Norwegian WAIS-III version, we tested factor models differing in the number of…

  7. Crystal structure of tris­(ethyl­enedi­ammonium) hexasulfatopraseodymium(III) hexa­hydrate

    PubMed Central

    Held, Peter

    2014-01-01

    In the title salt, (C2H10N2)3[Pr2(SO4)6]·6H2O, the PrIII cation is surrounded ninefold by five sulfate groups (two monodentate and three chelating) and by one water mol­ecule [range of Pr—O bond lengths 2.383 (3) to 2.582 (3) Å]. The [Pr(SO4)5(H2O)] groups are arranged in sheets parallel to (010). Two crystal water mol­ecules and two ethyl­enedi­ammonium cations (one with point group symmetry -1) connect the sheets via O—H⋯O and N—H⋯O hydrogen bonds from weak up to medium strength into a three-dimensional framework structure. PMID:25484661

  8. 4,2-Ribbon like ferromagnetic cyano-bridged Fe(III)2Ni(II) chains: a magneto-structural study.

    PubMed

    Toma, Luminita Marilena; Lescouëzec, Rodrigue; Uriel, Santiago; Llusar, Rosa; Ruiz-Pérez, Catalina; Vaissermann, Jacqueline; Lloret, Francesc; Julve, Miguel

    2007-09-07

    The low-spin iron(III) complex AsPh(4)[Fe(III)(bpy)(CN)(4)].CH(3)CN (1) [AsPh(4) = tetraphenylarsonium cation] and the heterobimetallic chains [{Fe(III)(L)(CN)(4)}(2)Ni(II)(H(2)O)(2)].4H(2)O with L = bpy (2) and phen (3) [bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline] have been prepared and their structures determined by X-ray diffraction methods. The structure of 1 consists of mononuclear [Fe(bpy)(CN)(4)](-) anions, tetraphenylarsonium cations and acetonitrile molecules of crystallization. The iron(III) is hexacoordinated with two nitrogen atoms of the bidentate bpy and four carbon atoms of four terminal cyanide groups building a distorted octahedral surrounding around the metal atom. 2 and 3 are isomorphous compounds whose structure is made up of neutral 4,2-ribbon like bimetallic chains of formula [{Fe(III)(L)(CN)(4)}(2)Ni(II)(H(2)O)(2)] where the [Fe(III)(L)(CN)(4)](-) unit acts as a bis-monodentate bridging ligand toward the trans-diaquanickel(II) units through two of its four cyanide groups in cis positions. The chains exhibit two orientations in the unit cell and they interact with each other through hydrogen bonds involving the coordination and crystallization water molecules together with the uncoordinated cyanide nitrogen atoms of the [Fe(L)(CN)(4)](-) units. Compounds 2 and 3 behave as ferromagnetic Fe(III)(2)Ni(II) chains which interact ferromagnetically at very low temperatures in the case of 2, whereas metamagnetic-like behaviour is observed for with a critical field (H(c)) around 200 G. For H > H(c) the ferromagnetic Fe(III)(2)Ni(II) chains of 3 exhibit a frequency dependence of the out-of-phase ac susceptibility signal at T < 3.5 K.

  9. Microstructural engineering applied to the controlled cooling of steel wire rod: Part III. Mathematical model-formulation and predictions

    NASA Astrophysics Data System (ADS)

    Campbell, P. C.; Hawbolt, E. B.; Brimacombe, J. K.

    1991-11-01

    In this final part of the study, a mathematical model incorporating heat flow, microstructural phenomena, and structure-composition-mechanical property relationships has been developed to compute the yield strength (YS) and ultimate tensile strength (UTS) of steel rod control cooled on a Stelmor line. The predictive capability of the model, in terms of temperature response, microstructural evolution, and strength of the rods, has been tested by comparison to measurements from an extensive set of laboratory and plant trials. Thus, the model has been shown to simulate the complex heat flow and microstructural phenomena in the steel rod very well, although improvements need to be sought in the characterization of the austenite-ferrite transformation kinetics and of pearlite interlamellar spacing. The latter variable has a significant influence on the strength of eutectoid steels. Nonetheless, the model consistently is capable of predicting the strengths of plain-carbon steel rods ranging from 1020 to 1080 to within ± 10 pet.

  10. Conserving intertidal habitats: What is the potential of ecological engineering to mitigate impacts of coastal structures?

    NASA Astrophysics Data System (ADS)

    Perkins, Matthew J.; Ng, Terence P. T.; Dudgeon, David; Bonebrake, Timothy C.; Leung, Kenneth M. Y.

    2015-12-01

    Globally, coastlines are under pressure as coastal human population growth and urbanization continues, while climatic change leads to stormier seas and rising tides. These trends create a strong and sustained demand for land reclamation and infrastructure protection in coastal areas, requiring engineered coastal defence structures such as sea walls. Here, we review the nature of ecological impacts of coastal structures on intertidal ecosystems, seek to understand the extent to which ecological engineering can mitigate these impacts, and evaluate the effectiveness of mitigation as a tool to contribute to conservation of intertidal habitats. By so doing, we identify critical knowledge gaps to inform future research. Coastal structures alter important physical, chemical and biological processes of intertidal habitats, and strongly impact community structure, inter-habitat linkages and ecosystem services while also driving habitat loss. Such impacts occur diffusely across localised sites but scale to significant regional and global levels. Recent advances in ecological engineering have focused on developing habitat complexity on coastal structures to increase biodiversity. 'Soft' engineering options maximise habitat complexity through inclusion of natural materials, species and processes, while simultaneously delivering engineering objectives such as coastal protection. Soft options additionally sustain multiple services, providing greater economic benefits for society, and resilience to climatic change. Currently however, a lack of inclusion and economic undervaluation of intertidal ecosystem services may undermine best practice in coastline management. Importantly, reviewed evidence shows mitigation and even restoration do not support intertidal communities or processes equivalent to pre-disturbance conditions. Crucially, an absence of comprehensive empirical baseline biodiversity data, or data comprising additional ecological parameters such as ecosystem functions

  11. Structural and oxo-transfer reactivity differences of hexacoordinate and pentacoordinate (nitro)(tetraphenylporphinato)cobalt(III) derivatives.

    PubMed

    Goodwin, J; Bailey, R; Pennington, W; Rasberry, R; Green, T; Shasho, S; Yongsavanh, M; Echevarria, V; Tiedeken, J; Brown, C; Fromm, G; Lyerly, S; Watson, N; Long, A; De Nitto, N

    2001-08-13

    The oxo-transfer catalyst (nitro)(pyridyl)cobalt(III) tetraphenylporphyrin has been reinvestigated by substitution of the distal pyridine ligand with 4-N,N-dimethylaminopyridine and 3,5-dichloropyridine. Differences in their structures and in the reactivity of the compounds toward catalytic secondary oxo transfer were investigated by FT-IR and UV-visible spectroscopy, cyclic voltammetry, X-ray diffraction, semiempirical calculations, and reactions with alkenes in dichloromethane solution. Very modest differences in the hexacoordinate compounds' structures were predicted and observed, but the secondary oxo-transfer reactivity at the nitro ligand varies markedly with the basicity of the pyridine ligand and the position of the coordination equilibrium. Oxo transfer occurs rapidly through the pentacoordinate species (nitro)cobalt(III) tetraphenylporphyrin that is generated by dissociation of the pyridine ligand and therefore is strongly related to the Hammett parameters of these nitrogenous bases. The reactive pentacoordinate species CoTPP(NO(2)) can be generated in solution by addition of lithium perchlorate to (py)CoTPP(NO(2)) by Lewis acid-base interactions or more simply by using the weaker Lewis base Cl(2)py instead of py as the distal ligand. In contrast to pentacoordinate (nitro)iron porphyrins, disproportionation reactions of CoTPP(NO(2)) compound are not evident. This pentacoordinate derivative, CoTPP(NO(2)), is reactive enough to stoichiometrically oxidize allyl bromide in minutes. Preliminary catalytic oxidation reaction studies of alkenes also indicate the involvement of both radical and nonradical oxo-transfer steps in the mechanism, suggesting formation of a peroxynitro intermediate in the reaction of the reduced CoTPP(NO) with O(2).

  12. Cloning and Structure-Function Analyses of Quinolone- and Acridone-producing Novel Type III Polyketide Synthases from Citrus microcarpa*

    PubMed Central

    Mori, Takahiro; Shimokawa, Yoshihiko; Matsui, Takashi; Kinjo, Keishi; Kato, Ryohei; Noguchi, Hiroshi; Sugio, Shigetoshi; Morita, Hiroyuki; Abe, Ikuro

    2013-01-01

    Two novel type III polyketide synthases, quinolone synthase (QNS) and acridone synthase (ACS), were cloned from Citrus microcarpa (Rutaceae). The deduced amino acid sequence of C. microcarpa QNS is unique, and it shared only 56–60% identities with C. microcarpa ACS, Medicago sativa chalcone synthase (CHS), and the previously reported Aegle marmelos QNS. In contrast to the quinolone- and acridone-producing A. marmelos QNS, C. microcarpa QNS produces 4-hydroxy-N-methylquinolone as the “single product” by the one-step condensation of N-methylanthraniloyl-CoA and malonyl-CoA. However, C. microcarpa ACS shows broad substrate specificities and produces not only acridone and quinolone but also chalcone, benzophenone, and phloroglucinol from 4-coumaroyl-CoA, benzoyl-CoA, and hexanoyl-CoA, respectively. Furthermore, the x-ray crystal structures of C. microcarpa QNS and ACS, solved at 2.47- and 2.35-Å resolutions, respectively, revealed wide active site entrances in both enzymes. The wide active site entrances thus provide sufficient space to facilitate the binding of the bulky N-methylanthraniloyl-CoA within the catalytic centers. However, the active site cavity volume of C. microcarpa ACS (760 Å3) is almost as large as that of M. sativa CHS (750 Å3), and ACS produces acridone by employing an active site cavity and catalytic machinery similar to those of CHS. In contrast, the cavity of C. microcarpa QNS (290 Å3) is significantly smaller, which makes this enzyme produce the diketide quinolone. These results as well as mutagenesis analyses provided the first structural bases for the anthranilate-derived production of the quinolone and acridone alkaloid by type III polyketide synthases. PMID:23963450

  13. Polarized white light from hybrid organic/III-nitrides grating structures

    NASA Astrophysics Data System (ADS)

    Athanasiou, M.; Smith, R. M.; Ghataora, S.; Wang, T.

    2017-01-01

    Highly polarised white light emission from a hybrid organic/inorganic device has been achieved. The hybrid devices are fabricated by means of combining blue InGaN-based multiple quantum wells (MQWs) with a one-dimensional (1D) grating structure and down-conversion F8BT yellow light emitting polymer. The 1D grating structure converts the blue emission from unpolarised to highly polarised; Highly polarised yellow emission has been achieved from the F8BT polymer filled and aligned along the periodic nano-channels of the grating structure as a result of enhanced nano-confinement. Optical polarization measurements show that our device demonstrates a polarization degree of up to 43% for the smallest nano-channel width. Furthermore, the hybrid device with such a grating structure allows us to achieve an optimum relative orientation between the dipoles in the donor (i.e., InGaN/GaN MQWs) and the diploes in the acceptor (i.e., the F8BT), maximizing the efficiency of non-radiative energy transfer (NRET) between the donor and the acceptor. Time–resolved micro photoluminescence measurements show a 2.5 times enhancement in the NRET efficiency, giving a maximal NRET efficiency of 90%. It is worth highlighting that the approach developed paves the way for the fabrication of highly polarized white light emitters.

  14. Polarized white light from hybrid organic/III-nitrides grating structures

    PubMed Central

    Athanasiou, M.; Smith, R. M.; Ghataora, S.; Wang, T.

    2017-01-01

    Highly polarised white light emission from a hybrid organic/inorganic device has been achieved. The hybrid devices are fabricated by means of combining blue InGaN-based multiple quantum wells (MQWs) with a one-dimensional (1D) grating structure and down-conversion F8BT yellow light emitting polymer. The 1D grating structure converts the blue emission from unpolarised to highly polarised; Highly polarised yellow emission has been achieved from the F8BT polymer filled and aligned along the periodic nano-channels of the grating structure as a result of enhanced nano-confinement. Optical polarization measurements show that our device demonstrates a polarization degree of up to 43% for the smallest nano-channel width. Furthermore, the hybrid device with such a grating structure allows us to achieve an optimum relative orientation between the dipoles in the donor (i.e., InGaN/GaN MQWs) and the diploes in the acceptor (i.e., the F8BT), maximizing the efficiency of non-radiative energy transfer (NRET) between the donor and the acceptor. Time–resolved micro photoluminescence measurements show a 2.5 times enhancement in the NRET efficiency, giving a maximal NRET efficiency of 90%. It is worth highlighting that the approach developed paves the way for the fabrication of highly polarized white light emitters. PMID:28045123

  15. Electronic Structure of Pi Systems: Part III--Applications in Spectroscopy and Chemical Reactivity.

    ERIC Educational Resources Information Center

    Fox, Marye Anne; Matsen, F. A.

    1985-01-01

    Shows that electronic structure diagrams make more accurate predictions of spectral properties and chemical reactivity for simple pi systems than do either Huckel molecular orbital or valence bond theory alone. Topics addressed include absorption and photoelectron spectra, spin density distribution in radicals, and several problems regarding…

  16. Quantum chemical study of the Fe(III)-desferrioxamine B siderophore complex—Electronic structure, vibrational frequencies, and equilibrium Fe-isotope fractionation

    NASA Astrophysics Data System (ADS)

    Domagal-Goldman, S. D.; Paul, K. W.; Sparks, D. L.; Kubicki, J. D.

    2009-01-01

    This study presents molecular orbital/density functional theory (MO/DFT) calculations of the electronic structure, vibrational frequencies, and equilibrium isotope fractionation factors for iron desferrioxamine B (Fe-DFO-B) complexes in aqueous solution. In general, there was good agreement between the predicted properties of Fe(III)-DFO-B and previously published experimental and theoretical results. The predicted fractionation factor for equilibrium between Fe(III)-DFO-B and Fe(III)-catecholate at 22 °C, 0.68 ± 0.25‰, was in good agreement with a previously measured isotopic difference between bacterial cells and solution during the bacterial-mediated dissolution of hornblende [Brantley S. L., Liermann L. and Bullen T. D. (2001) Fractionation of Fe isotopes by soil microbes and organic acids. Geology29, 535-538]. Conceptually, this agreement is consistent with the notion that Fe is first removed from mineral surfaces via complexation with small organic acids (e.g., oxalate), subsequently sequestered by DFO-B in solution, and ultimately delivered to bacterial cells by Fe(III)-DFO-B complexes. The ability of DFO-B to discriminate between Fe(III) and Fe(II)/Al(III) was investigated with Natural Bond Orbital (NBO) analysis and geometry calculations of each metal-DFO-B complex. The results indicated that higher affinity for Fe(III) is not strictly a function of bond length but also the degree of Fe-O covalent bonding.

  17. Structure and Engineering of Francisella novicida Cas9

    PubMed Central

    Hirano, Hisato; Gootenberg, Jonathan S.; Horii, Takuro; Abudayyeh, Omar O.; Kimura, Mika; Hsu, Patrick D.; Nakane, Takanori; Ishitani, Ryuichiro; Hatada, Izuho; Zhang, Feng; Nishimasu, Hiroshi; Nureki, Osamu

    2016-01-01

    Summary The RNA-guided endonuclease Cas9 cleaves double-stranded DNA targets complementary to the guide RNA, and has been applied to programmable genome editing. Cas9-mediated cleavage requires a protospacer adjacent motif (PAM) juxtaposed with the DNA target sequence, thus constricting the range of targetable sites. Here, we report the 1.7 Å resolution crystal structures of Cas9 from Francisella novicida (FnCas9), one of the largest Cas9 orthologs, in complex with a guide RNA and its PAM-containing DNA targets. A structural comparison of FnCas9 with other Cas9 orthologs revealed striking conserved and divergent features among distantly related CRISPR-Cas9 systems. We found that FnCas9 recognizes the 5′-NGG-3′ PAM, and used the structural information to create a variant that can recognize the more relaxed 5′-YG-3′ PAM. Furthermore, we demonstrated that pre-assembled FnCas9 ribonucleoprotein complexes can be microinjected into mouse zygotes to edit endogenous sites with the 5′-YG-3′ PAMs, thus expanding the target space of the CRISPR-Cas9 toolbox. PMID:26875867

  18. Thermal-structural analyses of Space Shuttle Main Engine (SSME) hot section components

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Thompson, Robert L.

    1988-01-01

    Three dimensional nonlinear finite element heat transfer and structural analyses were performed for the first stage high pressure fuel turbopump (HPFTP) blade of the space shuttle main engine (SSME). Directionally solidified (DS) MAR-M 246 and single crystal (SC) PWA-1480 material properties were used for the analyses. Analytical conditions were based on a typical test stand engine cycle. Blade temperature and stress strain histories were calculated by using the MARC finite element computer code. The structural response of an SSME turbine blade was assessed and a greater understanding of blade damage mechanisms, convective cooling effects, and thermal mechanical effects was gained.

  19. Large-scale production and protein engineering of G protein-coupled receptors for structural studies

    PubMed Central

    Milić, Dalibor; Veprintsev, Dmitry B.

    2015-01-01

    Structural studies of G protein-coupled receptors (GPCRs) gave insights into molecular mechanisms of their action and contributed significantly to molecular pharmacology. This is primarily due to technical advances in protein engineering, production and crystallization of these important receptor targets. On the other hand, NMR spectroscopy of GPCRs, which can provide information about their dynamics, still remains challenging due to difficulties in preparation of isotopically labeled receptors and their low long-term stabilities. In this review, we discuss methods used for expression and purification of GPCRs for crystallographic and NMR studies. We also summarize protein engineering methods that played a crucial role in obtaining GPCR crystal structures. PMID:25873898

  20. Electrical detachment of cells for engineering capillary-like structures in a photocrosslinkable hydrogel.

    PubMed

    Osaki, Tatsuya; Kakegawa, Takahiro; Suzuki, Hiroaki; Fukuda, Junji

    2011-01-01

    A major challenge in tissue engineering is the fabrication of vascular networks capable of delivering oxygen and nutrients throughout tissue constructs. Because cells located more than a few hundred micrometers away from the nearest capillaries are susceptible to oxygen shortages, it is crucial to develop microscale technologies for engineering a vascular structure in three-dimensionally thick tissues. This study describes an electrochemical approach for fabricating capillary-like structures precisely aligned within micrometer distances, the internal surfaces of which are covered with vascular endothelial cells in a photocrosslinkable hydrogel.

  1. Structural insights for engineering binding proteins based on non-antibody scaffolds.

    PubMed

    Gilbreth, Ryan N; Koide, Shohei

    2012-08-01

    Engineered binding proteins derived from non-antibody scaffolds constitute an increasingly prominent class of reagents in both research and therapeutic applications. The growing number of crystal structures of these 'alternative' scaffold-based binding proteins in complex with their targets illustrate the mechanisms of molecular recognition that are common among these systems and those unique to each. This information is useful for critically assessing and improving/expanding engineering strategies. Furthermore, the structural features of these synthetic proteins produced under tightly controlled, directed evolution deepen our understanding of the underlying principles governing molecular recognition.

  2. Large-scale production and protein engineering of G protein-coupled receptors for structural studies.

    PubMed

    Milić, Dalibor; Veprintsev, Dmitry B

    2015-01-01

    Structural studies of G protein-coupled receptors (GPCRs) gave insights into molecular mechanisms of their action and contributed significantly to molecular pharmacology. This is primarily due to technical advances in protein engineering, production and crystallization of these important receptor targets. On the other hand, NMR spectroscopy of GPCRs, which can provide information about their dynamics, still remains challenging due to difficulties in preparation of isotopically labeled receptors and their low long-term stabilities. In this review, we discuss methods used for expression and purification of GPCRs for crystallographic and NMR studies. We also summarize protein engineering methods that played a crucial role in obtaining GPCR crystal structures.

  3. Structural integrity and durability for Space Shuttle main engine and future reusable space propulsion systems

    NASA Technical Reports Server (NTRS)

    Marsik, S. J.; Gawrylowicz, H. T.

    1986-01-01

    NASA is conducting a program which will establish a technology base for the orderly evolution of reusable space propulsion systems. As part of that program, NASA initiated a Structural Integrity and Durability effort for advanced high-pressure oxygen-hydrogen rocket engine technology. That effort focuses on the development of: (1) accurate analytical models to describe flow fields; aerothermodynamic loads; structural responses; and fatigue/fracture, from which life prediction codes can be evolved; and (2) advanced instrumentation with capabilities to verify the codes in an SSME-like environment as well as the potential for future use as diagnostic sensors for real-time condition monitoring of critical engine components.

  4. FIBER-TEX 1992: The Sixth Conference on Advanced Engineering Fibers and Textile Structures for Composites

    NASA Technical Reports Server (NTRS)

    Buckley, John D. (Editor)

    1993-01-01

    The FIBER-TEX 1992 proceedings contain the papers presented at the conference held on 27-29 Oct. 1992 at Drexel University. The conference was held to create a forum to encourage an interrelationship of the various disciplines involved in the fabrication of materials, the types of equipment, and the processes used in the production of advanced composite structures. Topics discussed were advanced engineering fibers, textile processes and structures, structural fabric production, mechanics and characteristics of woven composites, and the latest requirements for the use of textiles in the production of composite materials and structures as related to global activities focused on textile structural composites.

  5. Chapter D. The Loma Prieta, California, Earthquake of October 17, 1989 - Earth Structures and Engineering Characterization of Ground Motion

    USGS Publications Warehouse

    Holzer, Thomas L.

    1998-01-01

    This chapter contains two papers that summarize the performance of engineered earth structures, dams and stabilized excavations in soil, and two papers that characterize for engineering purposes the attenuation of ground motion with distance during the Loma Prieta earthquake. Documenting the field performance of engineered structures and confirming empirically based predictions of ground motion are critical for safe and cost effective seismic design of future structures as well as the retrofitting of existing ones.

  6. Two WV-MnIII bimetallic assemblies built by octacyanotungstate(v) and MnIII Schiff bases: molecular structures and a spin-flop transition.

    PubMed

    Ko, Hyun Hee; Lim, Jeong Hak; Yoo, Houng Sik; Kang, Jun Sung; Kim, Hyoung Chan; Koh, Eui Kwan; Hong, Chang Seop

    2007-05-28

    Two W(V)-Mn(III) bimetallic compounds, [Mn(Cl-salmen)(H(2)O)2]{[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8].2H(2)O (1.2H(2)O) [5-Clsalmen = N,N'-(1-methylethylene)bis(5-chlorosalicylideneiminato) dianion], which contains trinuclear Mn(2)W and isolated Mn(III) moieties, and [Mn(3-MeOsalcy)(H(2)O)2]3[W(CN)(8)].2H(2)O (2.2H(2)O) [3-MeOsalcy = N,N'-(trans-1,2-cyclohexanediylethylene)bis(3-methoxysalicylideneiminato) dianion] molecules were prepared in redox processes and characterized using X-ray analysis and magnetic measurements. Compound 1 is composed of the {[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8]}- trimer, in which two CN groups among eight in [W(CN)8](3-) bridge W(5+) and two Mn(3+) ions and the remaining CN ligands are hydrogen-bonded to water molecules or unbound, and the [Mn(Cl-salmen)(H(2)O)2]+ cation. Subsequently, two water molecules of the isolated cation are subject to hydrogen bonds. For 2, there are no covalent bonds among the subunits and six serial stacks of [Mn(3-MeOsalcy)(H(2)O)2]+ units are all hydrogen-bonded. The many hydrogen bonds found in both complexes eventually lead to three-dimensional networks. The magnetic studies for 1 reveal that antiferromagnetic interactions (J = -5.4 cm(-1)) between W(V) and Mn(III) centers within the trimer are transmitted via the bridging CN groups. Intermolecular antiferromagnetic couplings (zJ' = -0.2 cm(-1)) are also observed. The static and dynamic magnetic data of 1 demonstrate the existence of a field-induced spin-flop transition occurring among the clusters and monomeric molecules.

  7. Structural bone allograft combined with genetically engineered mesenchymal stem cells as a novel platform for bone tissue engineering.

    PubMed

    Xie, Chao; Reynolds, David; Awad, Hani; Rubery, Paul T; Pelled, Gadi; Gazit, Dan; Guldberg, Robert E; Schwarz, Edward M; O'Keefe, Regis J; Zhang, Xinping

    2007-03-01

    The presence of live periosteal progenitor cells on the surface of bone autografts confers better healing than devitalized allograft. We have previously demonstrated in a murine 4 mm segmental femoral bone-grafting model that live periosteum produces robust endochondral and intramembraneous bone formation that is essential for effective healing and neovascularization of structural bone grafts. To the end of engineering a live pseudo-periosteum that could induce a similar response onto devitalized bone allograft, we seeded a mesenchymal stem cell line stably transfected with human bone morphogenic protein-2/beta-galactosidase (C9) onto devitalized bone allografts or onto a membranous small intestinal submucosa scaffold that was wrapped around the allograft. Histology showed that C9-coated allografts displayed early cartilaginous tissue formation at day 7. By 6 and 9 weeks, a new cortical shell was found bridging the segmental defect that united the host bones. Biomechanical testing showed that C9-coated allografts displayed torsional strength and stiffness equivalent to intact femurs at 6 weeks and superior to live isografts at 9 weeks. Volumetric and histomorphometric micro-computed tomography analyses demonstrated a 2-fold increase in new bone formation around C9-coated allografts, which resulted in a substantial increase in polar moment of inertia (pMOI) due to the formation of new cortical shell around the allografts. Positive correlations between biomechanics and new bone volume and pMOI were found, suggesting that the biomechanical function of the grafted femur relates to both morphological parameters. C9-coated allograft also exhibited slower resorption of the graft cortex at 9 weeks than live isograft. Both new bone formation and the persistent allograft likely contributed to the improved biomechanics of C9-coated allograft. Taken together, we propose a novel strategy to combine structural bone allograft with genetically engineered mesenchymal stem cells as

  8. [Structure and function of the bacterial flagellar type III protein export system in Salmonella
].

    PubMed

    Minamino, Tohru

    2015-01-01

    The bacterial flagellum is a filamentous organelle that propels the bacterial cell body in liquid media. For construction of the bacterial flagellum beyond the cytoplasmic membrane, flagellar component proteins are transported by its specific protein export apparatus from the cytoplasm to the distal end of the growing flagellar structure. The flagellar export apparatus consists of a transmembrane export gate complex and a cytoplasmic ATPase ring complex. Flagellar substrate-specific chaperones bind to their cognate substrates in the cytoplasm and escort the substrates to the docking platform of the export gate. The export apparatus utilizes ATP and proton motive force across the cytoplasmic membrane as the energy sources to drive protein export and coordinates protein export with assembly by ordered export of substrates to parallel with their order of assembly. In this review, we summarize our current understanding of the structure and function of the flagellar protein export system in Salmonella enterica serovar Typhimurium.

  9. Coherent nanocavity structures for enhancement in internal quantum efficiency of III-nitride multiple quantum wells

    SciTech Connect

    Kim, T.; Liu, B.; Smith, R.; Athanasiou, M.; Gong, Y.; Wang, T.

    2014-04-21

    A “coherent” nanocavity structure has been designed on two-dimensional well-ordered InGaN/GaN nanodisk arrays with an emission wavelength in the green spectral region, leading to a massive enhancement in resonance mode in the green spectra region. By means of a cost-effective nanosphere lithography technique, we have fabricated such a structure on an InGaN/GaN multiple quantum well epiwafer and have observed the “coherent” nanocavity effect, which leads to an enhanced spontaneous emission (SE) rate. The enhanced SE rate has been confirmed by time resolved photoluminescence measurements. Due to the coherent nanocavity effect, we have achieved a massive improvement in internal quantum efficiency with a factor of 88, compared with the as-grown sample, which could be significant to bridge the “green gap” in solid-state lighting.

  10. Homogeneous Electrochemical Biosensor for Melamine Based on DNA Triplex Structure and Exonuclease III-Assisted Recycling Amplification.

    PubMed

    Fu, Caili; Liu, Chang; Li, Ying; Guo, Yajing; Luo, Fang; Wang, Peilong; Guo, Longhua; Qiu, Bin; Lin, Zhenyu

    2016-10-03

    Abasic site (AP site) in the triplex structure can recognize specific target with high selectivity. In this study, this character was first applied to develop a simple, sensitive, and selective homogeneous electrochemical biosensor for melamine determination. The assay combines the advantage of the high selectivity of the DNA triplex structure containing an AP site to melamine and high efficiency of exonuclease (Exo) III-assisted recycling amplification. DNA-1 (T1), DNA-2 (T2), poly[dA] probe containing an AP site (8A) and methylene blue-labeled DNA probe (dMB probe) were carefully designed. Melamine can specifically locate in the AP site through hydrogen bonding interaction between thymine and melamine to make T1, T2, and 8A close to each other, therefore, forming a stable T-melamine-T DNA triplex structure. Under the optimal conditions, the differential pulse voltammetric (DPV) response had a linear relationship with the logarithm of melamine concentration in the range of 1 nM∼0.5 μM. The developed biosensor has been successfully applied to detect the migration of melamine from melamine bowl. Result showed that the migration in 4% acetic acid solvent was the largest, which is similar to that detected by high performance liquid chromatography. This homogeneous electrochemical sensor may have a potential prospect in detecting melamine in dairy products and migration of melamine from multicategory food packaging or application materials.

  11. Steric structure and thermodynamic aspects of the complexes of dysprosium (III) with aminobenzoic acids in aqueous solutions

    SciTech Connect

    Kondrashina, Yu, G.; Mustafina, A.R.; Vul`fson, S.G.

    1994-10-01

    Steric structures of dysprosium (III) aminobenzoate complexes with the 1:1 and 1:2 molar ratio in aqueous solutions were determined on the basis of pH-metric and paramagnetic birefringence data. An increase in conjugation observed for the series of the acids, viz., benzoic, meta-, ortho-, and para-aminobenzoic acids, results in the increased stability of the complexes with the 1:1 and 1:2 composition. In the case of para-aminobenzoic acid, the polyhedra [DyL(H{sub 2}O){sub 6}]{sup 2+} and [DyL{sub 2}(H{sub 2}O){sub 4}]{sup +} are cubes with the ligands coordinated to one and two edges, respectively. In the case of meta-aminobenzoic acid, the polyhedra [DyL(H{sub 2}O){sub 6}]{sup 2+} and [DyL{sub 2}(H{sub 2}O){sub 4}]{sup +} are a dodecahedron with the ligand coordinated to one edge and a square anti-prism with the ligands coordinated to two edges, respectively. In the case of ortho-aminobenzoic acid, both the 1:1 and 1:2 complexes have structures that are intermediate between the structures of meta- and para-aminobenzoic acids.

  12. Comparison of Epitaxial Growth Techniques for III-V Layer Structures

    DTIC Science & Technology

    1992-05-22

    FOR Ill-V LAYER STRUCTURES DTIC byS ELECTE G. B. STRINGFELLOW MAY 2 819S2 A Prepared for Publication in the Proceedings of croissance de cristaux et de...epitaxial growth techniques have been used for semiconductors, including liquid phase epitaxy (LPE), chloride vapor phase epitaxy (CIVPE) using...MBE (GSMBE), organometallic MBE (OMMBE or MOMBE), and chemical beam epitaxy (CBE). II. LIQUID PHASE EPITAXY The first technique listed, LPE, was one of

  13. Hydrothermal synthesis and structural characterization of ammonium ion-templated lanthanide(III) carboxylate-phosphonates

    PubMed Central

    Ayi, Ayi A.; Kinnibrugh, Tiffany L.; Clearfield, Abraham

    2014-01-01

    Using N-(phosphonomethyl) iminodiacetic acid (H4PMIDA), as a complexing agent, two new complexes, (NH4)La(PMIDA)(H2O)•H2O, 1 and (NH4)Yb(PMIDA), 2 have been synthesized hydrothermally. In both compounds, the metal ions are trapped by a three five-membered chelate rings by the chelating PMIDA anions giving a tricapped trigonal prismatic LaO8N and monocapped trigonal prismatic YbO6N geometries for 1 and 2, respectively. The structure of 1 consists of La(PMIDA)(H2O) chelating units, linked together by the phosphonate oxygen atoms O1 and O3 to form a chain along the c-axis. The chains are then connected together by the bridging phosphonate oxygen O2 to form a 2D layered structure with alternating 4- and 8-membered apertures. The structure of 2 consists Yb(PMIDA) chelating units, which are connected by alternating bridging carboxylate and phosphonate groups along the [010] direction forming chains with a corrugated pattern. The third phosphonate oxygen bridges the chains together along the [001] direction to build the two-dimensional layer with 4- and 6-membered apertures in the bc-plane. Under excitation of 330 nm, compound 2 shows a broad emission band at λmax = 460 nm. This emission is essentially in the blue luminescent region, which corresponds to ligand centered fluorescence. PMID:25414845

  14. Real-space electron transfer in III-nitride metal-oxide-semiconductor-heterojunction structures

    NASA Astrophysics Data System (ADS)

    Saygi, S.; Koudymov, A.; Adivarahan, V.; Yang, J.; Simin, G.; Khan, M. Asif; Deng, J.; Gaska, R.; Shur, M. S.

    2005-07-01

    The real-space transfer effect in a SiO2/AlGaN /GaN metal-oxide-semiconductor heterostructure (MOSH) from the two-dimensional (2D) electron gas at the heterointerface to the oxide-semiconductor interface has been demonstrated and explained. The effect occurs at high positive gate bias and manifests itself as an additional step in the capacitance-voltage (C-V) characteristic. The real-space transfer effect limits the achievable maximum 2D electron gas density in the device channel. We show that in MOSH structures the maximum electron gas density exceeds up to two times that at the equilibrium (zero bias) condition. Correspondingly, a significant increase in the maximum channel current (up to two times compared to conventional Schottky-gate structures) can be achieved. The real-space charge transfer effect in MOSH structures also opens up a way to design novel devices such as variable capacitors, multistate switches, memory cells, etc.

  15. Nanometer-Scale Compositional Structure in III-V Semiconductor Heterostructures Characterized by Scanning Tunneling Microscopy

    SciTech Connect

    Allerman, A.A.; Bi, W.G.; Biefeld, R.M.; Tu, C.W.; Yu, E.T.; Zuo, S.L.

    1998-11-10

    Nanometer-scale compositional structure in InAsxP1.InNYAsxPl.x-Y/InP, grown by gas-source molecular-beam epitaxy and in InAsl-xPJkAsl$b#InAs heterostructures heterostructures grown by metal-organic chemical vapor deposition has been characterized using cross-sectional scanning tunneling microscopy. InAsxP1-x alloy layers are found to contain As-rich and P-rich clusters with boundaries formed preferentially within (T 11) and (111) crystal planes. Similar compositional structure is observed within InNYAsxP1-x-Y alloy layers. Imaging of InAsl-xp@Asl#bY superlattices reveals nanometer-scale clustering within both the hAsI-.p and InAsl$bY alloy layers, with preferential alignment of compositional features in the direction. Instances are observed of compositional structure correlated across a heterojunction interface, with regions whose composition corresponds to a smaller unstrained lattice, constant relative to the surrounding alloy material appearing to propagate across the interface.

  16. Structure, optical properties and defects in nitride (III-V) nanoscale cage clusters.

    PubMed

    Shevlin, S A; Guo, Z X; van Dam, H J J; Sherwood, P; A Catlow, C R; Sokol, A A; Woodley, S M

    2008-04-14

    Density Functional Theory calculations are reported on cage structured BN, AlN, GaN and InN sub- and low nanosize stoichiometric clusters, including two octahedral families of T(d) and T(h) symmetry. The structures and energetics are determined, and we observe that BN clusters in particular show high stability with respect to the bulk phase. The cluster formation energy is demonstrated to include a constant term that we attribute to the curvature energy and the formation of six tetragonal defects. The (BN)(60) onion double-bubble structure was found to be particularly unstable. In contrast, similar or greater stability was found for double and single shell cages for the other nitrides. The optical absorption spectra have been first characterised by the one-electron Kohn-Sham orbital energies for all compounds, after which we concentrated on BN where we employed a recently developed Time Dependent Density Functional Theory approach. The one-electron band gaps do not show a strong and consistent size dependency, in disagreement with the predictions of quantum confinement theory. The density of excited bound states and absorption spectrum have been calculated for four smallest BN clusters within the first ionisation potential cut-off energy. The relative stability of different BN clusters has been further explored by studying principal point defects and their complexes including topological B-N bond rotational defects, vacancies, antisites and interstititials. The latter have the lowest energy of formation.

  17. Vibration-based health monitoring and model refinement of civil engineering structures

    SciTech Connect

    Farrar, C.R.; Doebling, S.W.

    1997-10-01

    Damage or fault detection, as determined by changes in the dynamic properties of structures, is a subject that has received considerable attention in the technical literature beginning approximately 30 years ago. The basic idea is that changes in the structure`s properties, primarily stiffness, will alter the dynamic properties of the structure such as resonant frequencies and mode shapes, and properties derived from these quantities such as modal-based flexibility. Recently, this technology has been investigated for applications to health monitoring of large civil engineering structures. This presentation will discuss such a study undertaken by engineers from New Mexico Sate University, Sandia National Laboratory and Los Alamos National Laboratory. Experimental modal analyses were performed in an undamaged interstate highway bridge and immediately after four successively more severe damage cases were inflicted in the main girder of the structure. Results of these tests provide insight into the abilities of modal-based damage ID methods to identify damage and the current limitations of this technology. Closely related topics that will be discussed are the use of modal properties to validate computer models of the structure, the use of these computer models in the damage detection process, and the general lack of experimental investigation of large civil engineering structures.

  18. Patterning and structural engineering of dimensionally constrained functional oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Pan, Zixiao

    The current trend of ceramic nanotechnology has motivated an ever-increasing need to achieve exquisite control over size, shape, and spatial confinement for functional oxide architectures, in an equivalent manner demonstrated for semiconductors. However, the unique nature of ceramics has posed major challenges for most traditional nanofabrication technologies, putting the development of innovative oxide nanopatterning schemes under the spotlight. Dimensional and spatial confinement of functional oxides has also raised extensive intellectual interests since it carries a profound bearing upon their microstructure variation and leads to often superior performances. This further underlines the need for exploring the "materials science and engineering" of nano-constrained oxides, i.e., to fabricate nanopatterns with precise geometrical control at various dimensionalities, and to tailor their microstructural and functional characteristics. This dissertation presents one strategy to achieve such objectives. We have developed a versatile nanofabrication approach, termed variable pressure-soft-electron beam lithography (VP-soft-eBL) that successfully resolves the generic challenges in patterning oxides and enables high resolution fabrication of diverse materials on a multitude of substrates. A strategy based on VP-soft-eBL was derived for microstructural and morphological control on the nanostructures, particularly that of ferroelectrics and ferrimagnets. The effect of pattern aspect ratio on the microstructure evolution has been investigated for CoFe 2O4 and BaTiO3 nanodiscs on single crystal substrates with appropriate lattice matching. Following this strategy, high quality epitaxial patterns can be readily achieved from amorphous form during annealing. VP-soft-eBL portfolio was then expanded significantly towards multi-dimensional patterning capability to facilitate systematic study on the confinement phenomena. We investigated the beam skirt effect on electron energy

  19. Syntheses, structures, and magnetic properties of acetato- and diphenolato-bridged 3d-4f binuclear complexes [M(3-MeOsaltn)(MeOH)x(ac)Ln(hfac)2] (M = Zn(II), Cu(II), Ni(II), Co(II); Ln = La(III), Gd(III), Tb(III), Dy(III); 3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato; ac = acetato; hfac = hexafluoroacetylacetonato; x = 0 or 1).

    PubMed

    Towatari, Masaaki; Nishi, Koshiro; Fujinami, Takeshi; Matsumoto, Naohide; Sunatsuki, Yukinari; Kojima, Masaaki; Mochida, Naotaka; Ishida, Takayuki; Re, Nazzareno; Mrozinski, Jerzy

    2013-05-20

    A series of 3d-4f binuclear complexes, [M(3-MeOsaltn)(MeOH)x(ac)Ln(hfac)2] (x = 0 for M = Cu(II), Zn(II); x = 1 for M = Co(II), Ni(II); Ln = Gd(III), Tb(III), Dy(III), La(III)), have been synthesized and characterized, where 3-MeOsaltn, ac, and hfac denote N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, acetato, and hexafluoroacetylacetonato, respectively. The X-ray analyses demonstrated that all the complexes have an acetato- and diphenolato-bridged M(II)-Ln(III) binuclear structure. The Cu(II)-Ln(III) and Zn(II)-Ln(III) complexes are crystallized in an isomorphous triclinic space group P1, where the Cu(II) or Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of 3-MeOsaltn at the equatorial coordination sites and one oxygen atom of the bridging acetato ion at the axial site. The Co(II)-Ln(III) and Ni(II)-Ln(III) complexes are crystallized in an isomorphous monoclinic space group P2(1)/c, where the Co(II) or Ni(II) ion at the high-spin state has an octahedral coordination environment with N2O2 donor atoms of 3-MeOsaltn at the equatorial sites, and one oxygen atom of the bridged acetato and a methanol oxygen atom at the two axial sites. Each Ln(III) ion for all the complexes is coordinated by four oxygen atoms of two phenolato and two methoxy oxygen atoms of "ligand-complex" M(3-MeOsaltn), four oxygen atoms of two hfac(-), and one oxygen atom of the bridging acetato ion; thus, the coordination number is nine. The temperature dependent magnetic susceptibilities from 1.9 to 300 K and the field-dependent magnetization up to 5 T at 1.9 K were measured. Due to the important orbital contributions of the Ln(III) (Tb(III), Dy(III)) and to a lesser extent the M(II) (Ni(II), Co(II)) components, the magnetic interaction between M(II) and Ln(III) ions were investigated by an empirical approach based on a comparison of the magnetic properties of the M(II)-Ln(III), Zn(II)-Ln(III), and M(II)-La(III) complexes. The differences of χ(M)T and M

  20. Engine Structures Analysis Software: Component Specific Modeling (COSMO)

    NASA Technical Reports Server (NTRS)

    Mcknight, R. L.; Maffeo, R. J.; Schwartz, S.

    1994-01-01

    A component specific modeling software program has been developed for propulsion systems. This expert program is capable of formulating the component geometry as finite element meshes for structural analysis which, in the future, can be spun off as NURB geometry for manufacturing. COSMO currently has geometry recipes for combustors, turbine blades, vanes, and disks. Component geometry recipes for nozzles, inlets, frames, shafts, and ducts are being added. COSMO uses component recipes that work through neutral files with the Technology Benefit Estimator (T/BEST) program which provides the necessary base parameters and loadings. This report contains the users manual for combustors, turbine blades, vanes, and disks.