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1

Crystal Structure of the Caenorhabditis elegans Apoptosome Reveals an Octameric Assembly of CED-4  

SciTech Connect

The CED-4 homo-oligomer or apoptosome is required for initiation of programmed cell death in Caenorhabditis elegans by facilitating autocatalytic activation of the CED-3 caspase zymogen. How the CED-4 apoptosome assembles and activates CED-3 remains enigmatic. Here we report the crystal structure of the complete CED-4 apoptosome and show that it consists of eight CED-4 molecules, organized as a tetramer of an asymmetric dimer via a previously unreported interface among AAA{sup +} ATPases. These eight CED-4 molecules form a funnel-shaped structure. The mature CED-3 protease is monomeric in solution and forms an active holoenzyme with the CED-4 apoptosome, within which the protease activity of CED-3 is markedly stimulated. Unexpectedly, the octameric CED-4 apoptosome appears to bind only two, not eight, molecules of mature CED-3. The structure of the CED-4 apoptosome reveals shared principles for the NB-ARC family of AAA{sup +} ATPases and suggests a mechanism for the activation of CED-3.

Qi, S.; Li, H.; Pang, Y.; Hu, Q., Liu, Q., Li, H.; Zhou, Y.; He, T.; Liang, Q.; Liu, Y.; Yuan, X.; Luo, G.; Wang, J.; Yan, N.; Shi, Y.

2010-04-30

2

Free radical-induced inactivation of creatine kinase: influence on the octameric and dimeric states of the mitochondrial enzyme (Mib-CK).  

PubMed

Free radicals of X-ray-induced water radiolysis, either directly or indirectly via their reaction products, reduce the activity of both dimeric cytoplasmic muscle-type creatine kinase (MM-CK) and octameric mitochondrial creatine kinase (Mi-CK) to virtually zero. Similarly values of the characteristic D(37)-dose of enzyme inactivation (dose required to reduce enzyme activity to 37%) were found for the two isoenzymes of CK under identical conditions. Octamer stability was not significantly affected within the dose range considered. However, both the dissociation of octamers into dimers by a transition-state analogue complex (TSAC), and the reassociation of the dimers into octamers, showed dose-dependent reduction. Binding of the TSAC to the active centre was found to protect the enzyme against inactivation by free radicals. No protection was observed for the radiation-induced decrease of the endogenous tryptophan fluorescence. The experimental results are in line with the following interpretation: (i) the reduction of Mi(b)-CK dimer association is due to free radical-induced modification of Trp-264, situated at the dimer/dimer interface; (ii) the active-site Trp-223 is not a prime target for free radicals and is not involved in the inactivation of the enzyme; (iii) the inhibition of TSAC-induced dissociation of Mi(b)-CK, like enzyme inactivation, is primarily due to a modification of the active-site Cys-278. PMID:10567223

Koufen, P; Rück, A; Brdiczka, D; Wendt, S; Wallimann, T; Stark, G

1999-12-01

3

Free radical-induced inactivation of creatine kinase: influence on the octameric and dimeric states of the mitochondrial enzyme (Mib-CK).  

PubMed Central

Free radicals of X-ray-induced water radiolysis, either directly or indirectly via their reaction products, reduce the activity of both dimeric cytoplasmic muscle-type creatine kinase (MM-CK) and octameric mitochondrial creatine kinase (Mi-CK) to virtually zero. Similarly values of the characteristic D(37)-dose of enzyme inactivation (dose required to reduce enzyme activity to 37%) were found for the two isoenzymes of CK under identical conditions. Octamer stability was not significantly affected within the dose range considered. However, both the dissociation of octamers into dimers by a transition-state analogue complex (TSAC), and the reassociation of the dimers into octamers, showed dose-dependent reduction. Binding of the TSAC to the active centre was found to protect the enzyme against inactivation by free radicals. No protection was observed for the radiation-induced decrease of the endogenous tryptophan fluorescence. The experimental results are in line with the following interpretation: (i) the reduction of Mi(b)-CK dimer association is due to free radical-induced modification of Trp-264, situated at the dimer/dimer interface; (ii) the active-site Trp-223 is not a prime target for free radicals and is not involved in the inactivation of the enzyme; (iii) the inhibition of TSAC-induced dissociation of Mi(b)-CK, like enzyme inactivation, is primarily due to a modification of the active-site Cys-278.

Koufen, P; Ruck, A; Brdiczka, D; Wendt, S; Wallimann, T; Stark, G

1999-01-01

4

CENP-A confers a reduction in height on octameric nucleosomes  

PubMed Central

Nucleosomes in which histone H3 is replaced by CENP-A direct kinetochore assembly. CENP-A nucleosomes extracted from human and Drosophila cells have been reported to have reduced heights relative to canonical octameric H3 nucleosomes, suggesting a unique tetrameric, hemisomal composition. We demonstrate that even octameric CENP-A nucleosomes assembled in vitro exhibit a reduced height, indicating that they are physically distinct from H3 nucleosomes, and negating the need to invoke the presence of hemisomes.

Miell, Matthew D. D.; Fuller, Colin J.; Guse, Annika; Barysz, Helena M.; Downes, Andrew; Owen-Hughes, Tom; Rappsilber, Juri; Straight, Aaron F.; Allshire, Robin C.

2013-01-01

5

Functional differences between dimeric and octameric mitochondrial creatine kinase.  

PubMed Central

Mitochondrial creatine kinase (Mi-CK) consists of octameric and dimeric molecules that are interconvertible. In the present study, the kinetic properties of purified chicken heart Mi-CK (Mib-CK) dimers and octamers were investigated separately under highly controlled conditions. Gel-permeation chromatography was performed before and after kinetic measurements in order to clearly define the proportions of octamers and dimers. 'Dimeric' Mi-CK solutions consisted of > or = 90% dimers throughout the experiment whereas 'octameric' Mi-CK solutions consisted in the beginning of 90% octamers, but upon measuring with the highest concentrations of creatine (Cr) and ATP approximately one-third of the octamers dissociated into dimers. These proper controls enabled us to pinpoint the observed kinetic differences between dimers and octamers solely to the oligomeric state of Mib-CK. Both dimeric and octameric Mi-CK displayed synergism in substrate binding (Kd values are higher than Km values), meaning that binding of the first substrate facilities subsequent binding of the second substrate. Most interestingly, Km(Cr) and Kd(Cr) values are both 2-3 times higher for octameric than for dimeric Mi-CK. Thus, at low Cr concentrations, the dimer is kinetically favoured for the forward direction of the reaction (phosphorylcreatine synthesis) compared with the octamer. The possible physiological significance of the lower Kd(Cr) value of dimeric versus octameric Mib-CK, as well as the apparent negative cooperativity of ATP binding at higher [Cr], are discussed within the context of a possible functional role for dimeric Mib-CK in vivo.

Kaldis, P; Wallimann, T

1995-01-01

6

Electron microscopic studies of the translin octameric ring.  

PubMed

Translin is thought to participate in a variety of cellular activities including chromosomal translocations, translational regulation of mRNA expression, and mRNA transport. It forms an octameric ring structure capable of sequence-specific binding of both DNA and RNA substrates. We have used electron microscopy and single-particle image analysis to generate a three-dimensional reconstruction of the Translin ring. The subunits appear to have two distinct domains that assemble to form an open channel with diameter of approximately 30 A at one end and approximately 50 A at the opposite end. In the presence of either DNA or RNA containing consensus binding sequences, the largest opening into the central cavity is filled with density. Strikingly, although Translin shows significant sequence homology to only one other protein, Translin-associated factor X, the quaternary organization and the dimerization of subunits in the ring are very similar to those observed for hexameric ring helicases. This suggests that many of the structures in DNA and RNA metabolism may have similar quaternary organization. PMID:11562166

VanLoock, M S; Yu, X; Kasai, M; Egelman, E H

2001-07-01

7

From pico to nano: biofunctionalization of cube-octameric silsesquioxanes by peptides and miniproteins.  

PubMed

Polyhedral silsesquioxanes are considered valuable conjugation scaffolds. Nevertheless, only a few examples of silsesquioxane-assembled peptide oligomers have been reported to date. We developed a new bioorthogonal cube-octameric silsesquioxane (COSS) scaffold bearing eight aminooxy coupling sites allowing for the conjugation of diverse peptides via oxime ligation. We found that the coupling efficacy depends on the ligand in view of steric hindrance and electrostatic repulsion. For the first time scaffold-based conjugation of cystine-knot miniproteins having a backbone of about thirty amino acids was successfully accomplished without loss of bioactivity. Atomic force microscopy (AFM) provided further knowledge on the size of COSS verifying them as picoscaffolds growing upon bioconjugation to nano-dimension. PMID:22733169

Fabritz, Sebastian; Hörner, Sebastian; Könning, Doreen; Empting, Martin; Reinwarth, Michael; Dietz, Christian; Glotzbach, Bernhard; Frauendorf, Holm; Kolmar, Harald; Avrutina, Olga

2012-08-21

8

Cube-octameric silsesquioxane-mediated cargo peptide delivery into living cancer cells.  

PubMed

Cube octameric silsesquioxanes (COSS) are among the smallest nanoparticles known to date with a diameter of only 0.7 nm. We describe a COSS-based delivery system which allows for the drug targeting in human cells. It comprises a siloxane core with seven pendant aminopropyl groups and a fluorescently labeled peptidic ligand attached to one cage corner via a reversible disulfide bond to ensure its intracellular release. Bimodal amplitude-modulated atomic force microscopy (AFM) experiments revealed the formation of dendritic COSS structures by a self-assembly of single particles on negatively charged surfaces. Nuclear targeting was demonstrated in HeLa cells by selective binding of released p21(Cip1/Waf1)-derived cargo peptide to PCNA, a protein involved in DNA replication and repair. PMID:23250285

Hörner, Sebastian; Fabritz, Sebastian; Herce, Henry D; Avrutina, Olga; Dietz, Christian; Stark, Robert W; Cardoso, M Cristina; Kolmar, Harald

2013-04-14

9

A role for the octameric ring protein, Translin, in mitotic cell division.  

PubMed

The octameric ring protein, Translin, demonstrates marked similarities to the family of helicase enzymes regarding its quaternary organization and dimerization of subunits. Here we show that the level of Translin closely parallels the proliferative state in various cell types. Expression is periodic during the cell cycle, with protein synthesis becoming maximal in the S and mitosis phases, consistent with a role in cell division. Moreover, induced overexpression of Translin was found to accelerate cell proliferation. Confocal microscopic analysis revealed that Translin is localized at the centrosomes at prophase and the mitotic spindle at metaphase, then translocating to the spindle midbodies during cytokinesis. This novel localization is attributable to specific interactions with microtubules of the mitotic spindles, and especially gamma-tubulin. The results suggest that Translin participates in processes ensuring the segregation of chromosomes and cytokinesis. PMID:12163170

Ishida, Reiko; Okado, Haruo; Sato, Hiroko; Shionoiri, Chieko; Aoki, Katsunori; Kasai, Masataka

2002-08-14

10

Structural Basis of hAT Transposon End Recognition by Hermes, an Octameric DNA Transposase from Musca domestica.  

PubMed

Hermes is a member of the hAT transposon superfamily that has active representatives, including McClintock's archetypal Ac mobile genetic element, in many eukaryotic species. The crystal structure of the Hermes transposase-DNA complex reveals that Hermes forms an octameric ring organized as a tetramer of dimers. Although isolated dimers are active in vitro for all the chemical steps of transposition, only octamers are active in vivo. The octamer can provide not only multiple specific DNA-binding domains to recognize repeated subterminal sequences within the transposon ends, which are important for activity, but also multiple nonspecific DNA binding surfaces for target capture. The unusual assembly explains the basis of bipartite DNA recognition at hAT transposon ends, provides a rationale for transposon end asymmetry, and suggests how the avidity provided by multiple sites of interaction could allow a transposase to locate its transposon ends amidst a sea of chromosomal DNA. PMID:25036632

Hickman, Alison B; Ewis, Hosam E; Li, Xianghong; Knapp, Joshua A; Laver, Thomas; Doss, Anna-Louise; Tolun, Gökhan; Steven, Alasdair C; Grishaev, Alexander; Bax, Ad; Atkinson, Peter W; Craig, Nancy L; Dyda, Fred

2014-07-17

11

Octamerization Enables Soluble CD46 Receptor To Neutralize Measles Virus In Vitro and In Vivo  

PubMed Central

A chimeric fusion protein encompassing the CD46 ectodomain linked to the C-terminal part of the C4b binding protein (C4bp) ? chain (sCD46-C4bp?) was produced in eukaryotic cells. This protein, secreted as a disulfide-linked homo-octamer, was recognized by a panel of anti-CD46 antibodies with varying avidities. Unlike monomeric sCD46, the octameric sCD46-C4bp? protein was devoid of complement regulatory activity. However, sCD46-C4bp? was able to bind to the measles virus hemagglutinin protein expressed on murine cells with a higher avidity than soluble monomeric sCD46. Moreover, the octameric sCD46-C4bp? protein was significantly more efficient than monomeric sCD46 in inhibiting virus binding to CD46, in blocking virus induced cell-cell fusion, and in neutralizing measles virus in vitro. In addition, the octameric sCD46-C4bp? protein, but not the monomeric sCD46, fully protected CD46 transgenic mice against a lethal intracranial measles virus challenge.

Christiansen, Dale; Devaux, Patricia; Reveil, Brigitte; Evlashev, Alexey; Horvat, Branka; Lamy, Josette; Rabourdin-Combe, Chantal; Cohen, Jacques H. M.; Gerlier, Denis

2000-01-01

12

Dimer-dimer interactions in octameric mitochondrial creatine kinase.  

PubMed

Mitochondrial creatine kinase (Mi-CK) forms octamers and dimers, which are readily interconvertible in vitro. The kinetic and thermodynamic octamer stability of wild-type and two mutant, octamer-destabilized forms of chicken sarcomeric Mi-CK was investigated at varying temperatures, pHs, and salt and substrate concentrations, in order to identify parameters which might regulate the octamer/dimer ratio in vivo and to assess the nature of octamer-stabilizing interactions. For wild-type Mi-CK, the rate of the transition state analogue complex (TSAC)-induced octamer decay increased with increasing temperature up to 28 degrees C; increasing pH markedly accelerated the decay in a biphasic manner. The substrate-dependent decay data suggest that also the productive enzymatic transition state of Mi-CK induces an octamer-destabilizing conformation. Thermodynamically, the octamers are stabilized by a combination of hydrophobic and polar contributions. Van't Hoff analysis showed that hydrophobic interactions dominate both in the absence of substrates and in the TSAC conformation, since the equilibrium octamer fractions increased with increasing temperatures, in spite of the accelerated decay kinetics. For the Mi-CK mutant E4Q, a similar temperature dependence was found; in contrast, mutant W264C exhibited an inverted temperature dependence, suggesting that hydrophobic interactions might be largely abolished in this mutant. Both the kinetic and the thermodynamic data seem to suggest that the octamer-dimer transitions of Mi-CK might not play a major role in a fast regulation of mitochondrial energy metabolism, but could rather be involved in slow long-term modulations. PMID:7756297

Gross, M; Wallimann, T

1995-05-23

13

Using Markov state models to study self-assembly.  

PubMed

Markov state models (MSMs) have been demonstrated to be a powerful method for computationally studying intramolecular processes such as protein folding and macromolecular conformational changes. In this article, we present a new approach to construct MSMs that is applicable to modeling a broad class of multi-molecular assembly reactions. Distinct structures formed during assembly are distinguished by their undirected graphs, which are defined by strong subunit interactions. Spatial inhomogeneities of free subunits are accounted for using a recently developed Gaussian-based signature. Simplifications to this state identification are also investigated. The feasibility of this approach is demonstrated on two different coarse-grained models for virus self-assembly. We find good agreement between the dynamics predicted by the MSMs and long, unbiased simulations, and that the MSMs can reduce overall simulation time by orders of magnitude. PMID:24907984

Perkett, Matthew R; Hagan, Michael F

2014-06-01

14

Octameric mitochondrial creatine kinase induces and stabilizes contact sites between the inner and outer membrane.  

PubMed

We have investigated the role of the protein ubiquitous mitochondrial creatine kinase (uMtCK) in the formation and stabilization of inner and outer membrane contact sites. Using liver mitochondria isolated from transgenic mice, which, unlike control animals, express uMtCK in the liver, we found that the enzyme was associated with the mitochondrial membranes and, in addition, was located in membrane-coated matrix inclusions. In mitochondria isolated from uMtCK transgenic mice, the number of contact sites increased 3-fold compared with that observed in control mitochondria. Furthermore, uMtCK-containing mitochondria were more resistant to detergent-induced lysis than wild-type mitochondria. We conclude that octameric uMtCK induces the formation of mitochondrial contact sites, leading to membrane cross-linking and to an increased stability of the mitochondrial membrane architecture. PMID:15294016

Speer, Oliver; Bäck, Nils; Buerklen, Tanja; Brdiczka, Dieter; Koretsky, Alan; Wallimann, Theo; Eriksson, Ove

2005-01-15

15

Octameric mitochondrial creatine kinase induces and stabilizes contact sites between the inner and outer membrane  

PubMed Central

We have investigated the role of the protein ubiquitous mitochondrial creatine kinase (uMtCK) in the formation and stabilization of inner and outer membrane contact sites. Using liver mitochondria isolated from transgenic mice, which, unlike control animals, express uMtCK in the liver, we found that the enzyme was associated with the mitochondrial membranes and, in addition, was located in membrane-coated matrix inclusions. In mitochondria isolated from uMtCK transgenic mice, the number of contact sites increased 3-fold compared with that observed in control mitochondria. Furthermore, uMtCK-containing mitochondria were more resistant to detergent-induced lysis than wild-type mitochondria. We conclude that octameric uMtCK induces the formation of mitochondrial contact sites, leading to membrane cross-linking and to an increased stability of the mitochondrial membrane architecture.

2004-01-01

16

Octamerization is essential for enzymatic function of human UDP-glucose pyrophosphorylase.  

PubMed

Uridine diphosphate-glucose pyrophosphorylase (UGP) occupies a central position in carbohydrate metabolism in all kingdoms of life, since its product uridine diphosphate-glucose (UDP-glucose) is essential in a number of anabolic and catabolic pathways and is a precursor for other sugar nucleotides. Its significance as a virulence factor in protists and bacteria has given momentum to the search for species-specific inhibitors. These attempts are, however, hampered by high structural conservation of the active site architecture. A feature that discriminates UGPs of different species is the quaternary organization. While UGPs in protists are monomers, di- and tetrameric forms exist in bacteria, and crystal structures obtained for the enzyme from yeast and human identified octameric UGPs. These octamers are formed by contacts between highly conserved amino acids in the C-terminal ?-helix. Still under debate is the question whether octamerization is required for the functionality of the human enzyme. Here, we used single amino acid replacements in the C-terminal ?-helix to interrogate the impact of highly conserved residues on octamer formation and functional activity of human UGP (hUGP). Replacements were guided by the sequence of Arabidopsis thaliana UGP, known to be active as a monomer. Correlating the data obtained in blue native PAGE, size exclusion chromatography and enzymatic activity testing, we prove that the octamer is the active enzyme form. This new insight into structure-function relationships in hUGP does not only improve the understanding of the catalysis of this important enzyme, but in addition broadens the basis for studies aimed at designing drugs that selectively inhibit UGPs from pathogens. PMID:23254995

Führing, Jana; Damerow, Sebastian; Fedorov, Roman; Schneider, Julia; Münster-Kühnel, Anja-Katharina; Gerardy-Schahn, Rita

2013-04-01

17

Multimeric assembly and biochemical characterization of the Trax/Translin endonuclease complex  

PubMed Central

Trax/Translin heteromers, also known as C3PO, have been proposed to activate RNA-induced silencing complex (RISC) by facilitating endonucleolytic cleavage of the siRNA passenger strand. We report on the crystal structure of hexameric Drosophila C3PO formed by truncated Translin and Trax, along with electron microscopic and mass spectrometric studies on octameric C3PO formed by full-length Translin and Trax. Our studies establish that Trax adopts the Translin fold, possesses catalytic centers essential for C3PO’s endoribonuclease activity and interacts extensively with Translin to form an octameric assembly. The catalytic pockets of Trax subunits are located within the interior chamber of the octameric scaffold. Truncated C3PO, like full-length, exhibits endoribonuclease activity leaving 3? hydroxyl-cleaved ends. We have measured the catalytic activity of C3PO and shown it to cleave near stoichiometric amounts of substrate per second.

Tian, Yuan; Simanshu, Dhirendra K.; Ascano, Manuel; Diaz-Avalos, Ruben; Park, Ah Young; Juranek, Stefan A.; Rice, William J.; Yin, Qian; Robinson, Carol V.; Tuschl, Thomas; Patel, Dinshaw J.

2011-01-01

18

The octameric structure of beta-glucosidase from Botryodiplodia theobromae Pat.  

PubMed Central

1. Whereas only beta-glucosidase A (beta-D-glucoside glucohydrolase, EC 3.2.1.21) was produced by the tropical fungus Botryodiplodia theobromae Pat. (I.M.I. 115626; A.T.C.C. 26123) in young cultures containing D-cellobiose as carbon source, lower-Mr forms (B, C and D) were found in older cultures when the pH had drifted from the initial value of pH 6.2 to pH 7.9. 2. The Michaelis constants (Km) of the various molecular forms of the enzyme were 0.30 +/- 0.03 mM-, 0.26 +/- 0.01 mM-, 0.20 +/- 0.02 mM- and 0.16 +/- 0.01 mM-o-nitrophenyl beta-D-glucopyranoside for beta-glucosidase forms A (Mr 320,000), B (Mr 160,000), C (Mr 80,000) and D (Mr 40,000) respectively. 3. Only beta-glucosidase D showed substrate inhibition. 4. Only L-arginine was found as the N-terminal residue, and beta-glucosidase A contained 31.7 +/- 0.6 mol of N-terminal L-arginine/mol of the enzyme. 5. Storage of purified beta-glucosidase A under mildly alkaline conditions caused its dissociation into the lower-Mr forms, whereas adjustment of the pH of a solution of beta-glucosidase A to pH 12.0 with 1 M-NaOH led to complete inactivation on incubation at 40 degrees C for 1 h and to the release of 25.2 +/- 1.5 mol of inorganic phosphate/mol of the enzyme. 6. O-Phospho-L-serine was isolated from the acid-hydrolysis product of beta-glucosidase A but not from that of beta-glucosidase D. 7. Reduction and carboxamidomethylation of the various forms of beta-glucosidase gave only one enzymically inactive protein with an Mr of 10,000-11,000. 8. After partial succinylation (3-carboxypropionylation) of beta-glucosidase D at pH 5.0 and removal of the precipitated protein formed, the supernatant solution contained beta-glucosidase components similar to the other molecular forms (A, B and C) and an aggregate (beta-glucosidase Xs) that gave a positive result in the alkaline hydroxylamine test, whereas N-succinylated beta-glucosidase D, an aggregate (form Xp) that behaved like beta-glucosidase Xs and traces of forms A, B and C were found by gel filtration of the solution of the precipitate solubilized at neutral pH (7.0-7.7). 9. These observations are discussed in terms of the proposed octameric structure of beta-glucosidase A based on the result of electron microscopy [Umezurike (1975) Biochem. J. 145, 361-368].

Umezurike, G M

1991-01-01

19

Steady-state thermal-hydraulic analysis of SCWR assembly  

Microsoft Academic Search

Among the six gen-IV reactor concepts recommended by the gen-IV international forum (GIF), supercritical water-cooled reactor\\u000a (SCWR), the only reactor with water as coolant, achieves a high thermal efficiency and, subsequently, has economic advantages\\u000a over the existing reactors due to its high outlet temperature. A thermal-hydraulic analysis of the SCWR assembly is performed\\u000a in this paper using the modified COBRA-IV

Xiaojing Liu; Xu Cheng

2008-01-01

20

Thermal-Fluid Analysis and Simulation of High Power Solid-State Laser Diode (SLD) Assemblies.  

National Technical Information Service (NTIS)

The thermal configuration is an important factor determining the successful operation of the high power solid-state laser diode assemblies. The solid-state diode array in an H-package using a conventional water-cooling flow was analyzed using a combined t...

L. L. Liou C. T. Tsai X. A. Zhu

2002-01-01

21

Ready to Assemble: Grading State Higher Education Accountability Systems  

ERIC Educational Resources Information Center

States need strong higher education systems, now more than ever. In the tumultuous, highly competitive 21st century economy, citizens and workers need knowledge, skills, and credentials in order to prosper. Yet many colleges and universities are falling short. To give all students the best possible postsecondary education, states must create…

Aldeman, Chad; Carey, Kevin

2009-01-01

22

Strain-Induced Localized States Within the Matrix Continuum of Self-Assembled Quantum Dots  

SciTech Connect

Quantum dot-based infrared detectors often involve transitions from confined states of the dot to states above the minimum of the conduction band continuum of the matrix. We discuss the existence of two types of resonant states within this continuum in self-assembled dots: (i) virtual bound states, which characterize square wells even without strain and (ii) strain-induced localized states. The latter emerge due to the appearance of 'potential wings' near the dot, related to the curvature of the dots. While states (i) do couple to the continuum, states (ii) are sheltered by the wings, giving rise to sharp absorption peaks.

Popescu, V.; Bester, G.; Zunger, A.

2009-07-01

23

Detection of a charge-separated catalyst precursor state in a linked photosensitizer-catalyst assembly.  

PubMed

We have designed two new supramolecular assemblies based on Co(ii)-templated coordination of Ru(bpy)3(2+) (bpy = 2,2'-bipyridyl) analogues as photosensitizers and electron donors to a cobaloxime macrocycle, which are of interest as proton reduction catalysts. The self-assembled photocatalyst precursors were structurally characterized by Co K-edge X-ray absorption spectroscopy and solution-phase X-ray scattering. Visible light excitation of one of the assemblies has yielded instantaneous electron transfer and charge separation to form a transient Co(i) state which persists for 26 ps. The development of a linked photosensitizer-cobaloxime architecture supporting efficient Co(i) charge transfer is significant since it is mechanistically critical as the first photo-induced electron transfer step for hydrogen production, and has not been detected in previous photosensitizer-cobaloxime linked dyad assemblies. X-band EPR spectroscopy has revealed that the Co(ii) centres of both assemblies are high spin, in contrast to most previously described cobaloximes, and likely plays an important role in facilitating photoinduced charge separation. Based on the results obtained from ultrafast and nanosecond transient absorption optical spectroscopies, we propose that charge recombination occurs through multiple ligand states present within the photosensitizer modules. The studies presented here will enhance our understanding of supramolecular photocatalyst assembly and direct new designs for artificial photosynthesis. PMID:24220293

Mukherjee, Anusree; Kokhan, Oleksandr; Huang, Jier; Niklas, Jens; Chen, Lin X; Tiede, David M; Mulfort, Karen L

2013-12-28

24

State of Nevada Telecommunications Study. Assembly Concurrent Resolution 68.  

ERIC Educational Resources Information Center

This document offers the results of a study of Nevada's telecommunications requirements, based on a comprehensive survey of existing networks associated with state and local governments, school districts, and the university system. It reports that Nevada can accrue benefits from telecommunications in the areas of education, economic development,…

Nevada State Dept. of General Services, Carson City.

25

Glutamine synthetase isolated from human brain: octameric structure and homology of partial primary structure with human liver glutamine synthetase.  

PubMed

Glutamine synthetase (GS) has been purified from the cytosolic fraction of non-frozen human brain tissue. The purified GS migrated as a main band around 44 kD on reducing SDS-PAGE. Two-dimensional electrophoresis revealed heterogeneity within subunits of GS. The masses of eight different peptides from a tryptic digest of GS as measured by high resolution MALDI-MS matched with the respective masses from an in silico tryptic fingerprint of the Swiss-Prot database entry of human liver GS, proving that at least 24% of the primary sequences of GS from brain and liver are identical. Sedimentation equilibrium profiles obtained from analytical ultracentrifugation experiments at 10 degrees C showed that human brain GS is mainly octameric. The quaternary structure of human brain GS at 10 microM (subunit concentration) was not significantly affected by cations, such as magnesium (5 and 20 mM) or manganese (0.2 and 1 mM) within the range of pH 7.1-7.8. PMID:12387715

Boksha, I S; Schönfeld, H-J; Langen, H; Müller, F; Tereshkina, E B; Burbaeva, G Sh

2002-09-01

26

Assembly of Tobacco Mosaic Virus In Vitro: Effect of State of Polymerization of the Protein Component  

PubMed Central

The in vitro assembly of tobacco mosaic virus from its constituent RNA and protein was followed by methods of electron microscopy. The effect of the state of polymerization of the protein upon the initiation of assembly of tobacco mosaic virus rods, and the subsequent rod elongation, was investigated. Protein in two identifiable states of polymerization was used: the 20S “disc”, consisting of 34 monomers arrayed as a two-ring structure, and the 4S “A-protein”, consisting of polymers in the trimer range of size. It is concluded, in confirmation of results of others, that rod assembly is initiated by the attachment of one end of the RNA chain of tobacco mosaic virus to one (or possibly a few) disc structure. Rod elongation, on the other hand, is found to take place by the sequential addition of structures of the size of A-protein, or smaller, to the previously initiated rods.

Richards, Kenneth E.; Williams, Robley C.

1972-01-01

27

19 CFR 10.25 - Textile components cut to shape in the United States and assembled abroad.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Textile components cut to shape in the United States and assembled abroad... § 10.25 Textile components cut to shape in the United States and assembled abroad. Where a textile component is cut to shape (but not to length, width,...

2009-04-01

28

Adsorption states of the self-assembly of NH3 molecules on the Si(001) surface  

NASA Astrophysics Data System (ADS)

Adsorption states of the self-assembly of NH3 molecules on the Si(001) surface are investigated using density-functional theory calculations. H-bond interactions between incoming and adsorbed NH3 molecules produce a strong attractive potential field for the incoming molecules. Induced by the H bonds, physisorption states are formed on the adsorbed NH3. Molecular adsorption states are formed on a buckled-down Si atom near the adsorbed NH3. Various physisorption, molecular and dissociative adsorption configurations are discussed.

Kim, Yong-Sung; Koo, Ja-Yong; Kim, Hanchul

2009-02-01

29

An Amyloid Organelle, Solid-state NMR Evidence for Cross-? Assembly of Gas Vesicles*  

PubMed Central

Functional amyloids have been identified in a wide range of organisms, taking on a variety of biological roles and being controlled by remarkable mechanisms of directed assembly. Here, we report that amyloid fibrils constitute the ribs of the buoyancy organelles of Anabaena flos-aquae. The walls of these gas-filled vesicles are known to comprise a single protein, GvpA, arranged in a low pitch helix. However, the tertiary and quaternary structures have been elusive. Using solid-state NMR correlation spectroscopy we find detailed evidence for an extended cross-? structure. This amyloid assembly helps to account for the strength and amphiphilic properties of the vesicle wall. Buoyancy organelles thus dramatically extend the scope of known functional amyloids.

Bayro, Marvin J.; Daviso, Eugenio; Belenky, Marina; Griffin, Robert G.; Herzfeld, Judith

2012-01-01

30

Solid state nanofibers based on self-assemblies: from cleaving from self-assemblies to multilevel hierarchical constructs.  

PubMed

Self-assemblies and their hierarchies are useful to construct soft materials with structures at different length scales and to tune the materials properties for various functions. Here we address routes for solid nanofibers based on different forms of self-assemblies. On the other hand, we discuss rational "bottom-up" routes for multi-level hierarchical self-assembled constructs, with the aim of learning more about design principles for competing interactions and packing frustrations. Here we use the triblock copolypeptide poly(L-lysine)-b-poly(gamma-benzyl-L-glutamate)-b-poly(L-lysine) complexed with 2'-deoxyguanosine 5'-monophosphate. Supramolecular disks (G-quartets) stabilized by metal cations are formed and their columnar assembly leads to a packing frustration with the cylindrical packing of helical poly(gamma-benzyl-L-glutamate), which we suggest is important in controlling the lateral dimensions of the nanofibers. We foresee routes for functionalities by selecting different metal cations within the G-quartets. On the other hand, we discuss nanofibers that are cleaved from bulk self-assemblies in a "top-down" manner. After a short introduction based on cleaving nanofibers from diblock copolymeric self-assemblies, we focus on native cellulose nanofibers, as cleaved from plant cell wall fibers, which are expected to have feasible mechanical properties and to be templates for functional nanomaterials. Long nanofibers with 5-20 nm lateral dimensions can be cleaved within an aqueous medium to allow hydrogels and water can be removed to allow highly porous, lightweight, and flexible aerogels. We further describe inorganic/ organic hybrids as prepared by chemical vapour deposition and atomic layer deposition of the different nanofibers. We foresee functional materials by selecting inorganic coatings. Finally we briefly discuss how the organic template can be removed e.g., by thermal treatments to allow completely inorganic hollow nanofibrillar structures. PMID:20334096

Ikkala, Olli; Ras, Robin H A; Houbenov, Nikolay; Ruokolainen, Janne; Pääkko, Marjo; Laine, Janne; Leskelä, Markku; Berglund, Lars A; Lindström, Tom; ten, Brinke Gerrit; Iatrou, Hermis; Hadjichristidis, Nikos; Faul, Charl F J

2009-01-01

31

Multimeric assembly and biochemical characterization of the Trax-translin endonuclease complex.  

PubMed

Trax-translin heteromers, also known as C3PO, have been proposed to activate the RNA-induced silencing complex (RISC) by facilitating endonucleolytic cleavage of the siRNA passenger strand. We report on the crystal structure of hexameric Drosophila C3PO formed by truncated translin and Trax, along with electron microscopic and mass spectrometric studies on octameric C3PO formed by full-length translin and Trax. Our studies establish that Trax adopts the translin fold, possesses catalytic centers essential for C3PO's endoRNase activity and interacts extensively with translin to form an octameric assembly. The catalytic pockets of Trax subunits are located within the interior chamber of the octameric scaffold. Truncated C3PO, like full-length C3PO, shows endoRNase activity that leaves 3'-hydroxyl-cleaved ends. We have measured the catalytic activity of C3PO and shown it to cleave almost stoichiometric amounts of substrate per second. PMID:21552261

Tian, Yuan; Simanshu, Dhirendra K; Ascano, Manuel; Diaz-Avalos, Ruben; Park, Ah Young; Juranek, Stefan A; Rice, William J; Yin, Qian; Robinson, Carol V; Tuschl, Thomas; Patel, Dinshaw J

2011-06-01

32

Transport spectroscopy of non-equilibrium many-particle spin states in self-assembled quantum dots.  

PubMed

Self-assembled quantum dots (QDs) are prominent candidates for solid-state quantum information processing. For these systems, great progress has been made in addressing spin states by optical means. In this study, we introduce an all-electrical measurement technique to prepare and detect non-equilibrium many-particle spin states in an ensemble of self-assembled QDs at liquid helium temperature. The excitation spectra of the one- (QD hydrogen), two- (QD helium) and three- (QD lithium) electron configuration are shown and compared with calculations using the exact diagonalization method. An exchange splitting of 10 meV between the excited triplet and singlet spin states is observed in the QD helium spectrum. These experiments are a starting point for an all-electrical control of electron spin states in self-assembled QDs above liquid helium temperature. PMID:21343927

Marquardt, B; Geller, M; Baxevanis, B; Pfannkuche, D; Wieck, A D; Reuter, D; Lorke, A

2011-01-01

33

Probing the Oligomeric Assemblies of Pea Porphobilinogen Synthase by Analytical Ultracentrifugation†  

PubMed Central

The enzyme porphobilinogen synthase (PBGS) can exist in different non-additive homo-oligomeric assemblies and, under appropriate conditions, the distribution of these assemblies can respond to ligands such as metals or substrate. PBGS from most organisms was believed to be octameric until work on a rare allele of human PBGS revealed an alternate hexameric assembly, which is also available to the wild type enzyme at elevated pH. Herein, we establish that the distribution of pea PBGS quaternary structures also contains octamers and hexamers, using both sedimentation velocity and sedimentation equilibrium experiments. We report results in which the octamer dominates under purification conditions and discuss conditions that influence the octamer:hexamer ratio. As predicted by PBGS crystal structures from related organisms, in the absence of magnesium, the octameric assembly is significantly destabilized and the oligomeric distribution is dominated largely by the hexameric assembly. Although the PBGS hexamer-to-octamer oligomeric rearrangement is well document under some conditions, both assemblies are very stable (under AUC conditions) in the timeframe of our ultracentrifuge experiments.

Kokona, Bashkim; Rigotti, Daniel J.; Wasson, Andrew S.; Lawrence, Sarah H.; Jaffe, Eileen K.; Fairman, Robert

2008-01-01

34

Many-body exciton states in self-assembled quantum dots coupled to a Fermi sea  

NASA Astrophysics Data System (ADS)

Using voltage dependent photoluminescence spectroscopy we have studied the coupling between QD states and the continuum of states of a Fermi sea of electrons in the close proximity of a self-assembled InAs quantum dot embedded in GaAs. This coupling gives rise to new optical transitions, manifesting the formation of many-body exciton states. The lines in the photoluminescence spectra can be well explained within the Anderson and Mahan exciton models. The presence of Mahan excitons originates from the Coulomb interaction between electrons in the Fermi sea and the hole(s) in the QD whereas a the second type of many-body exciton is due to a hybridized exciton originating from the tunnel interaction between the continuum of states in the Fermi sea and the localized state in the QD. Our study demonstrates the possibility to investigate a variety of many-body states in QDs coupled to a Fermi sea and opens the way to investigate optically the Kondo effect and related spin phenomena in these systems.

Koenraad, P. M.; Kleemans, N. A. J. M.; van Bree, J.; Govorov, A. O.; Hamhuis, G. J.; Notzel, R.; Silov, A. Yu.

2010-03-01

35

A Note on the Ground State Energy of an Assembly of Interacting Electrons  

PubMed Central

The ground state energy of an assembly of charged particles of density ? imbedded in a continuum of charge of the other sign in an electrically neutral system is considered. Asymptotic formulae for the ground state energy of such systems are known in the high- and low-density regimes. An interpolation formula covering the entire density range is derived using the method of two-point Padé approximants. A phase transition from an electron lettice to an electron gas seems to occur at r3 ? 14, r3 being the radius of a sphere which, on the average, contains a single charge, in units of the Bohr radius of the electron in a hydrogen atom.

Isihara, Akira; Montroll, Elliott W.

1971-01-01

36

A note on the ground state energy of an assembly of interacting electrons.  

PubMed

The ground state energy of an assembly of charged particles of density rho imbedded in a continuum of charge of the other sign in an electrically neutral system is considered. Asymptotic formulae for the ground state energy of such systems are known in the high- and low-density regimes. An interpolation formula covering the entire density range is derived using the method of two-point Padé approximants. A phase transition from an electron lettice to an electron gas seems to occur at r(3) congruent with 14, r(3) being the radius of a sphere which, on the average, contains a single charge, in units of the Bohr radius of the electron in a hydrogen atom. PMID:16591957

Isihara, A; Montroll, E W

1971-12-01

37

Supramolecular cobaloxime assemblies for H{sub 2} photocatalysis: an initial solution state structure-function analysis.  

SciTech Connect

In this report, we have investigated the correlations between structure and light-induced electron transfer of one known and three new axially coordinated cobaloxime-based supramolecular photocatalysts for the reduction of protons to hydrogen. Solution-phase X-ray scattering and ultrafast transient optical spectroscopy analyses were used in tandem to correlate the self-assembled photocatalysts structural integrity in solution with electron transfer and charge separation between the photosensitizer and catalyst fragments. Biphasic excited state decay kinetics were observed for several of the assemblies, suggesting that configurational dispersion plays a role in limiting photoinduced electron transfer. Notably, an assembly featuring a 'push-pull' donor-photosensitizer-acceptor triad motif exhibits considerable ultrafast excited state quenching and, of the assemblies examined, presents the strongest opportunity for efficient solar energy conversion. These results will assist in the design and development of next-generation supramolecular photocatalyst architectures.

Mulfort, K. L.; Tiede, D. M. (Chemical Sciences and Engineering Division)

2010-01-01

38

19 CFR 10.25 - Textile components cut to shape in the United States and assembled abroad.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Textile components cut to shape in the United...United States Components § 10.25 Textile components cut to shape in the United States and assembled abroad. Where a textile component is cut to shape (but...

2013-04-01

39

Structural and dynamical characterization of tubular HIV-1 capsid protein assemblies by solid state nuclear magnetic resonance and electron microscopy  

PubMed Central

The wild-type HIV-1 capsid protein (CA) self-assembles in vitro into tubular structures at high ionic strength. We report solid state nuclear magnetic resonance (NMR) and electron microscopy measurements on these tubular CA assemblies, which are believed to contain a triangular lattice of hexameric CA proteins that is similar or identical to the lattice of capsids in intact HIV-1. Mass-per-length values of CA assemblies determined by dark-field transmission electron microscopy indicate a variety of structures, ranging from single-wall tubes to multiwall tubes that approximate solid rods. Two-dimensional (2D) solid state 13C—13C and 15N—13C NMR spectra of uniformly 15N,13C-labeled CA assemblies are highly congested, as expected for a 25.6 kDa protein in which nearly the entire amino acid sequence is immobilized. Solid state NMR spectra of partially labeled CA assemblies, expressed in 1,3-13C2-glycerol medium, are better resolved, allowing the identification of individual signals with line widths below 1 ppm. Comparison of crosspeak patterns in the experimental 2D spectra with simulated patterns based on solution NMR chemical shifts of the individual N-terminal (NTD) and C-terminal (CTD) domains indicates that NTD and CTD retain their individual structures upon self-assembly of full-length CA into tubes. 2D 1H-13C NMR spectra of CA assemblies recorded under solution NMR conditions show relatively few signals, primarily from segments that link the ?-helices of NTD and CTD and from the N- and C-terminal ends. Taken together, the data support the idea that CA assemblies contain a highly ordered 2D protein lattice in which the NTD and CTD structures are retained and largely immobilized.

Chen, Bo; Tycko, Robert

2010-01-01

40

Image Potential States - A Probe of the Surface and Electronic Structure of Self-Assembled Monolayers  

NASA Astrophysics Data System (ADS)

Electrons in image potential states (IPSs) are easily observed on clean and coated metal surfaces. An IPS model has been successfully applied to spectra produced via surface-enhanced electronic Raman scattering (SEERS) from a roughened metal substate coated with a self-assembled alkanethiol monolayer.[1,2] The IPS model and SEERS excitation spectra are used to locate the position of the electron in the monolayer, establish the presence of a partially populated energy band between the Fermi level and the vacuum level, and detect variations in the image plane distance that are related to the location and strength of bonds between the monolayer and the substrate. [1] B. K. Clark, B. W. Gregory, A. Avila, T. M. Cotton, and J. M. Standard, J. Phys. Chem. B 103, 8201, 1999. [2] B. K. Clark, B. W. Gregory, and J. M. Standard, Phys. Rev. B, (accepted, Fall 2000 publication).

Clark, B. K.; Gregory, B. W.; Standard, J. M.

2001-03-01

41

[Photoluminescence investigation of InAs bimodal self-assembled quantum dots state filling].  

PubMed

Self-assembled InAs quantum dots were prepared on GaAs(100) substrate in a solid source molecular beam epitaxy system. The distribution and topographic images of uncapped dots were studied by atomic force microscope. The statistical result shows that the quantum dots are bimodal distribution. The photoluminescence spectrum results shows that the intensity of small size quantum dots dominated, which may be due to: (1) the state density of large quantum dots lower than that of small quantum dots; (2) the carriers capture rate of large size quantum dots is small relative to that of small ones; (3) there is a large strain barrier between large quantum dots and capping layer, and the large strain is likely to produce the defect and dislocation, resulting in a probability of carriers transferring from large quantum dots to small dots that is very small with temperature increasing. PMID:18260388

Jia, Guo-Zhi; Yao, Jiang-Hong; Zhang, Chun-Ling; Shu, Qiang; Liu, Ru-Bin; Ye, Xiao-Ling; Wang, Zhan-Guo

2007-11-01

42

Diverging neural pathways assemble a behavioural state from separable features in anxiety.  

PubMed

Behavioural states in mammals, such as the anxious state, are characterized by several features that are coordinately regulated by diverse nervous system outputs, ranging from behavioural choice patterns to changes in physiology (in anxiety, exemplified respectively by risk-avoidance and respiratory rate alterations). Here we investigate if and how defined neural projections arising from a single coordinating brain region in mice could mediate diverse features of anxiety. Integrating behavioural assays, in vivo and in vitro electrophysiology, respiratory physiology and optogenetics, we identify a surprising new role for the bed nucleus of the stria terminalis (BNST) in the coordinated modulation of diverse anxiety features. First, two BNST subregions were unexpectedly found to exert opposite effects on the anxious state: oval BNST activity promoted several independent anxious state features, whereas anterodorsal BNST-associated activity exerted anxiolytic influence for the same features. Notably, we found that three distinct anterodorsal BNST efferent projections-to the lateral hypothalamus, parabrachial nucleus and ventral tegmental area-each implemented an independent feature of anxiolysis: reduced risk-avoidance, reduced respiratory rate, and increased positive valence, respectively. Furthermore, selective inhibition of corresponding circuit elements in freely moving mice showed opposing behavioural effects compared with excitation, and in vivo recordings during free behaviour showed native spiking patterns in anterodorsal BNST neurons that differentiated safe and anxiogenic environments. These results demonstrate that distinct BNST subregions exert opposite effects in modulating anxiety, establish separable anxiolytic roles for different anterodorsal BNST projections, and illustrate circuit mechanisms underlying selection of features for the assembly of the anxious state. PMID:23515158

Kim, Sung-Yon; Adhikari, Avishek; Lee, Soo Yeun; Marshel, James H; Kim, Christina K; Mallory, Caitlin S; Lo, Maisie; Pak, Sally; Mattis, Joanna; Lim, Byung Kook; Malenka, Robert C; Warden, Melissa R; Neve, Rachael; Tye, Kay M; Deisseroth, Karl

2013-04-11

43

DNA translocation through a solid-state nanopore coated with a self-assembled monolayer  

NASA Astrophysics Data System (ADS)

The translocation of DNA through a solid-state nanopore can be dramatically affected by surface properties of a pore, such as charge density, roughness and hydrophobicity, since the pore surface serves as a boundary for the hydrodynamic flow accompanying with DNA motion. Recent experiment demonstrated the coating of a self-assembled monolayer (SAM) on the surface of a nanopore, allowing an active control on the surface property. Using all-atom molecular dynamics simulation, we investigated the tribological effect on DNA translocation through a solid-state nanopore coated with a SAM. When DNA is confined to the center of a pore, i.e. no direct interaction between DNA and pore surface, charge density and roughness of a pore surface can affect electroosmotic and hydrodynamic flows inside a nanopore, respectively. When allowing direct interaction between DNA and a SAM, adhesive interaction via hydrogen bonds can substantially increase friction force on DNA during translocation but repulsive interaction permits a fast translocation of DNA. We found two types of motion of DNA, stick-slip and steady-sliding, that are qualitatively explained using a Langevin-like model.

Luan, Binquan; Stolovitzky, Gustavo; Martyna, Glenn

2011-03-01

44

Solid-state scrolls from hierarchical self-assembly of T-shaped rod-coil molecules.  

PubMed

On a roll: Attachment of flexible coils to the middle of a rigid rod generates T-shaped rod-coil molecules that self-assemble into layers that roll up to form filled cylindrical and hollow tubular scrolls, depending on the coil length, in the solid state (see picture); the rods are arranged parallel to the layer plane. PMID:19072811

Hong, Dong-Je; Lee, Eunji; Jeong, Haemi; Lee, Jeong-kyu; Zin, Wang-Cheol; Nguyen, Trung Dac; Glotzer, Sharon C; Lee, Myongsoo

2009-01-01

45

Assembly and Comparison of Different Equations of State for Multiphase Carbon Dioxide in the Subsurface  

NASA Astrophysics Data System (ADS)

Sequestration of carbon dioxide in deep saline aquifers has been suggested as a possible means for reducing greenhouse gas concentrations in the atmosphere. For geological sequestration, an accurate equation-of-state (EOS) is critical for evaluating and estimating migration and ultimate diagenetic effects on permeability and porosity. We assembled, coded, and compared two different EOS algorithms. One is the modified Redlich-Kwong (MRK) EOS, which employs modification of the attractive term from van der Waals equation. The other is Span and Wagner's (SW) EOS, an empirical representation of the fundamental equation of Helmholtz energy. Using these fundamentally different EOS, the density, fugacity, and enthalpy of carbon dioxide in the gas and supercritical phases were simulated for several test case models. Results included some disparities between simulated and experimental data. Furthermore, for some simulations small errors were compounded and induced very significant impacts on ultimate carbon dioxide plume migration and associated subsurface chemical reactions. In particular, aqueous carbon dioxide solubility calculations by the two EOS algorithms reflected large differences, especially during longer time-scale simulations. In sum, results suggest that even small differences in thermodynamic properties of carbon dioxide, as calculated between the MRK and SW EOS, may produce magnified differences in ultimate projections of subsurface plume histories and associated chemical reaction processes.

Han, W.; McPherson, B. J.

2004-12-01

46

Magnetic ordered states induced by interparticle magnetostatic interaction in ?-Fe/Au mixed nanoparticle assembly.  

PubMed

The magnetic behavior of ?-Fe/Au nanoparticle (NP) assemblies is studied over a very wide range of dipolar interactions among ?-Fe NPs, by changing the volume density of the ?-Fe NP. The assembly whose ?-Fe NP density is lower than 0.1% exhibits typical superparamagnetic behavior. When Fe NP density exceeds 8.6% the magnetic dynamics changes to that resembling superspin glass. Moreover, NP assembly with highest Fe concentration (43%), whose dipolar interaction is enormously strong compared with previous studies, exhibits a two-stage magnetic transition, i.e., ferromagnetic and spin glass-like transitions at 385?K and around 150?K, respectively. Therefore, we first observed the reentrant spin glass-like magnetism at the limit of strong interaction in a close-packed NP assembly. Based on these observations, the magnetic phase diagram of the interacting ?-Fe NP assembly is determined over a very wide range of interaction. PMID:24713627

Hiroi, Kosuke; Kura, Hiroaki; Ogawa, Tomoyuki; Takahashi, Migaku; Sato, Tetsuya

2014-04-30

47

Fucoxanthin-chlorophyll proteins in diatoms: 18 and 19 kDa subunits assemble into different oligomeric states.  

PubMed

Fucoxanthin-chlorophyll proteins were purified from the centric diatom Cyclotella meneghiniana. Two major fractions were observed that differed in their polypeptide composition and oligomeric state. Trimers consist of mainly 18 kDa polypeptides. Higher oligomers are tightly assembled from different trimers, which contain mostly 19 kDa subunits. In both oligomeric states, the excitation energy coupling between fucoxanthin and chlorophyll a was preserved, and chlorophyll c was shown to transfer energy efficiently to chlorophyll a. Circular dichroism spectra showed close interaction between fucoxanthin and chlorophyll a, and different chlorophyll a molecules were demonstrated to interact excitonically. The assembly of trimers of antenna proteins with a distinct subunit composition into higher oligomeric states was not reported so far and differs from the situation found in higher plants. The differences in the supramolecular structure of the fucoxanthin-chlorophyll proteins reflect the dissimilar arrangement of the thylakoid membranes in diatoms, which lack the grana-stroma distinction. PMID:14596618

Büchel, Claudia

2003-11-11

48

Long-term self-assembly of inorganic layered materials influenced by the local states of the interlayer cations.  

PubMed

A wide variety of parameters as, e.g., temperature, humidity, particle size, and cation state are known to influence the agglomeration process of two-dimensional (2D) nanosheets, called self-assembly, in inorganic layered materials. The detailed studies on which parameters are decisive and how they influence the self-assembly, however, have not been performed yet. Here, the long-term self-assembly was studied for layered stevensite and hectorite, and compared with our previous data of saponite for elucidating an influence of local states of the interlayer cations. The results were analyzed with respect to a recently established rheological model, in which 2D nanosheets migrate parallel to the layer direction aided by water molecules as lubricants [K. Sato et al., J. Phys. Chem. C, 2012, 116, 22954]. With decreasing the strength of the local electric fields facing to the interlayer spaces, cation positions split into two or three, which makes the distribution of water molecules more uniformly. These water molecules enhance the rheological motion of the 2D nanosheets parallel to the layer direction, thus accelerating the self-assembly process. PMID:24770790

Sato, Kiminori; Numata, Kazuomi; Dai, Weili; Hunger, Michael

2014-06-14

49

Lateral photoconductivity and bound states of self-assembled Ge\\/Si quantum dots  

Microsoft Academic Search

We have investigated lateral conduction mid-infrared photodetectors using the photoionization of holes in the valence band of self-assembled Ge\\/Si quantum dots. A mid-infrared photocurrent signal was observed in the photon energy range of 140-400 meV resulting from an intersubband transition in the valence band of self-assembled Ge quantum dots and subsequent lateral transport of photoexcited carriers in the SiGe conduction

S.-W. Lee; T. G. Kim; K. Hirakawa; J. S. Kim; S.-H. Choi; H. Y. Cho

2007-01-01

50

Lateral photoconductivity and bound states of self-assembled Ge\\/Si quantum dots  

Microsoft Academic Search

We have investigated lateral conduction mid-infrared photodetectors using the photoionization of holes in the valence band of self-assembled Ge\\/Si quantum dots. A mid-infrared photocurrent signal was observed in the photon energy range of 140–400 meV resulting from an intersubband transition in the valence band of self-assembled Ge quantum dots and subsequent lateral transport of photoexcited carriers in the SiGe conduction

S-W Lee; T G Kim; K Hirakawa; J S Kim; S-H Choi; H Y Cho

2007-01-01

51

Phosphonate self-assembled monolayers as organic linkers in solid-state quantum dot sensetized solar cells  

Microsoft Academic Search

We have employed X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) spectroscopy, infrared (IR) spectroscopy, water contact angle (WCA) measurements, ellipsometry, and electrical measurements to study the effects of self-assembled monolayers (SAMs) with phosphonic acid headgroups on the bonding and performance of cadmium sulfide (CdS) solid-state quantum dot sensitized solar cells (QDSSCs). ~2 to ~6 nm size CdS quantum dots (QDs) were

Pendar Ardalan; Thomas P. Brennan; Jonathan R. Bakke; S. F. Bent

2010-01-01

52

Solid-State Nanostructured Materials from Self-Assembly of a Globular Protein-Polymer Diblock Copolymer  

PubMed Central

Self-assembly of three-dimensional solid-state nanostructures containing approximately 33% by weight globular protein is demonstrated using a globular protein-polymer diblock copolymer, providing a route to direct nanopatterning of proteins for use in bioelectronic and biocatalytic materials. A mutant red fluorescent protein, mCherryS131C, was prepared by incorporation of a unique cysteine residue and site-specifically conjugated to end-functionalized poly(N-isopropylacrylamide) through thiol-maleimide coupling to form a well-defined model protein-polymer block copolymer. The block copolymer was self-assembled into bulk nanostructures by solvent evaporation from concentrated solutions. Small-angle X-ray scattering and transmission electron microscopy illustrated the formation of highly disordered lamellae or hexagonally perforated lamellae depending upon the selectivity of the solvent during evaporation. Solvent annealing of bulk samples resulted in a transition towards lamellar nanostructures with mCherry packed in a bilayer configuration and a large improvement in long range ordering. Wide-angle X-ray scattering indicated that mCherry did not crystallize within the block copolymer nanodomains and that the ?-sheet spacing was not affected by self-assembly. Circular dichroism showed no change in protein secondary structure after self-assembly, while UV-vis spectroscopy indicated approximately 35% of the chromophore remained optically active.

Thomas, Carla S.; Glassman, Matthew J.; Olsen, Bradley D.

2014-01-01

53

Three distinct equilibrium states via self-assembly: simple access to a supramolecular ion-controlled NAND logic gate.  

PubMed

During the past several decades, considerable effort has focused on self-assembled systems. However, most work has been directed toward understanding the equilibrium between two major chemical entities, namely the dissociated components and the corresponding associated complex. While there are quite a few examples of 'multiresponsive' materials, control over 'multistate' materials has proved difficult to achieve. Here, we report the formation and the interplay of a self-assembled calix[4]pyrrole array that exhibits three limiting forms, namely a 1:1 self-assembled oligomer, a 2:1 capsule, and the corresponding monomers. Interconversion between these states may be controlled by using the tetraethylammonium cation (TEA(+)) and/or iodide anion (I(-)) as chemical inputs. The combination of self-assembly and ion-based control may be used to create systems that display NAND logic behavior. The system outputs have been confirmed by a variety of analytic methods, including UV-vis and 2D (1)H DOSY, NOESY NMR spectroscopy, scanning electron microscopy, and single crystal X-ray diffraction analyses. PMID:24011216

Kim, Dong Sub; Lynch, Vincent M; Park, Jung Su; Sessler, Jonathan L

2013-10-01

54

Empirical validation of viral quasispecies assembly algorithms: state-of-the-art and challenges  

PubMed Central

Next generation sequencing (NGS) is superseding Sanger technology for analysing intra-host viral populations, in terms of genome length and resolution. We introduce two new empirical validation data sets and test the available viral population assembly software. Two intra-host viral population ‘quasispecies’ samples (type-1 human immunodeficiency and hepatitis C virus) were Sanger-sequenced, and plasmid clone mixtures at controlled proportions were shotgun-sequenced using Roche's 454 sequencing platform. The performance of different assemblers was compared in terms of phylogenetic clustering and recombination with the Sanger clones. Phylogenetic clustering showed that all assemblers captured a proportion of the most divergent lineages, but none were able to provide a high precision/recall tradeoff. Estimated variant frequencies mildly correlated with the original. Given the limitations of currently available algorithms identified by our empirical validation, the development and exploitation of additional data sets is needed, in order to establish an efficient framework for viral population reconstruction using NGS.

Prosperi, Mattia C. F.; Yin, Li; Nolan, David J.; Lowe, Amanda D.; Goodenow, Maureen M.; Salemi, Marco

2013-01-01

55

Encapsulated discrete octameric water cluster, 1D water tape, and 3D water aggregate network in diverse MOFs based on bisimidazolium ligands  

NASA Astrophysics Data System (ADS)

Four new metal-organic frameworks, [Zn(2-mBIM)2(SO3CF3)2·(H2O)4] (1), [Zn(BMIE)(1,4-BDC)]·(H2O)3 (2), [Cd(BIM)2(OH)(H2O)2(PF6)]·(H2O)4 (3), and [Cd(PA-BIM)2 (ClO4)2]·11.33H2O (4) (2-mBIM = bis(2-methylimidazol-1-yl)methane, BMIE = 1,2-bis[1-(2-methylimidazole)-diethoxy]ethane, BIM = bis(imidazol-1-yl)methane, and PA-BIM = 1,1-bis [(2-phenylazo)imidazol-1-yl]methane) have been prepared and structurally characterized. Complex 1 exhibits an infinite 1D cationic beaded-chain structure, which encapsulated discrete octameric water clusters that are comprised of a chair-like hexameric water cluster with two extra water molecules dangling on two diagonal vertices of the chair. Complex 2 forms a 1D infinite zigzag metal-organic chain structure with a 1D T4(0)A(4) water tape. Complexes 3 show a 2D grid-like sheet structure with the 1D water tape T4(0)A(0)2(0) motif. Complex 4 is a porous 3D MOF with tetrahedron-coordinated Cd(II) centers and trans-conformation PA-BIM ligands. These holes are occupied by a fascinating three-dimensional water clathrate network, which consists of cage-shaped structural tetradecameric water cluster (H2O)14 units and six independent bridged water molecules. The results suggest that the bisimidazolium ligands and anions play crucial roles in the formation of the different host structures and different guest water aggregations. Additionally, the thermal stabilities and photoluminescence spectra of the complexes have been discussed.

Shi, Ruo-Bing; Pi, Min; Jiang, Shuang-Shuang; Wang, Yuan-Yuan; Jin, Chuan-Ming

2014-08-01

56

Optimized assembly and steady-state length-scale control in dissipative systems of photo-switchable colloids  

NASA Astrophysics Data System (ADS)

Photo-switchable nanoparticles, such as those developed by Wei et al.,footnotetextY.H. Wei, S. B. Han, J. Kim, S. L. Soh and B. A. Grzybowski, J. Am. Chem. Soc., 2010, 132, 11018-11020. can be assembled into a broad range of structures using light exposure as a control parameter. Jha et al.footnotetextP.k. Jha, V. Kuzovkov, B.A. Grzybowski, and M. Olvera del la Cruz, Soft Matter, 2012, 8, 227-234 explored the evolution of these structures using kinetic Monte Carlo simulations. In this work, we build on these studies using Molecular Dynamics with a Langevin thermostat to, by judicious choice of exposure parameters that control the dissipative nature of the system, engineer and optimize the self-assembly pathways as well as control the length scales of the steady-state structures.

Osorio-Vivanco, Antonio; Olvera de La Cruz, Monica; Glotzer, Sharon

2013-03-01

57

Complexin is able to bind to SNARE core complexes in different assembled states with distinct affinity  

Microsoft Academic Search

The formation of the functional SNARE complex in vivo is central to the fast neurotransmitter release at the neuronal terminal. Numerous studies revealed that this process involves progressive assembly of an ?-helical bundle and is dynamically reversible. So far many proteins directly or indirectly take part in this process. Complexin, one of such factors, has revealed rapid association with the

Jingguo Liu; Ting Guo; Yong Wei; Ming Liu; Sen-Fang Sui

2006-01-01

58

Time-resolved transconductance spectroscopy on self-assembled quantum dots: Spectral evolution from single- into many-particle states  

NASA Astrophysics Data System (ADS)

Using transconductance spectroscopy we study the tunneling dynamics of electrons from a two-dimensional electron gas (2DEG) into excited and ground states of a layer of self-assembled InAs quantum dots (QDs). From an initially selected nonequilibrium condition, we observe the charging dynamics of the QD states and their spectral evolution for one- and two-electron configurations. Furthermore, we measure the electron emission from the QD states into the 2DEG for the corresponding evolution of the QD-hydrogen and QD-helium spectra. The comparison with theoretically predicted energies, as well as the evaluation of the dynamics in charging and emission, allows us to separate and identify ground and excited electron configurations in the spectral evolution and discuss in detail the observed maxima in the different spectra.

Beckel, A.; Ludwig, A.; Wieck, A. D.; Lorke, A.; Geller, M.

2014-04-01

59

Structure and excited state relaxation dynamics in nanoscale self-assembled arrays: multiporphyrin complexes, porphyrin-quantum dot composites  

NASA Astrophysics Data System (ADS)

Self-assembled nanoscale arrays of controllable geometry and composition (up to 8 tetrapyrroles) have been formed via non-covalent binding interactions of the meso-phenyl bridged Zn-octaethylporphyrin chemical dimers or trimers with di- /tetrapyridyl substituted porphyrin extra-ligands. In these complexes using steady-state and time-resolved (ps fluorescence and fs pump-probe) measurements pathways and efficiencies of the energy transfer photoinduced charge separation as well as exchange d-? effects have been studied in solutions of variable polarity at 77-293 K. The same principles of aggregation via the key-hole scheme "Zn-pyridyl" have been used also for the surface passivation of pyridylsubstituted tetrapyrroles on the coreshell semiconductor CdSe/ZnS quantum dots (QD) showing quantum confinement effects. Picosecond time-resolved and steady-state data reveal that CdSe/ZnS QD emission is multiexponential and the efficiency of its quenching by attached porphyrins (due to energy transfer and photoinduced charge separation) depends strongly on the number of anchoring groups their arrangement in the porphyrin molecule as well as on QD size and number of ZnS monolayers. The analysis of spectroscopic and kinetic findings reveals that on average only ~l/5 porphyrin molecules are assembled on the QD and a limited number of "vacancies" accessible for porphyrin attachment is available on the QD surface.

Zenkevich, E. I.; von Borczyskowski, C.

2005-06-01

60

Zinc chlorins for artificial light-harvesting self-assemble into antiparallel stacks forming a microcrystalline solid-state material  

PubMed Central

We introduce a concept to solve the structure of a microcrystalline material in the solid-state at natural abundance without access to distance constraints, using magic angle spinning (MAS) NMR spectroscopy in conjunction with X-ray powder diffraction and DFT calculations. The method is applied to a novel class of materials that form (semi)conductive 1D wires for supramolecular electronics and artificial light-harvesting. The zinc chlorins 3-devinyl-31-hydroxymethyl-132-demethoxycarbonylpheophorbide a (3?,5?-bis-dodecyloxy)benzyl ester zinc complex 1 and 3-devinyl-31-methoxymethyl-132-demethoxycarbonylpheophorbide a (3?,5?-bis-dodecyloxy)benzyl ester zinc complex 2, self-assemble into extended excitonically coupled chromophore stacks. 1H-13C heteronuclear dipolar correlation MAS NMR experiments provided the 1H resonance assignment of the chlorin rings that allowed accurate probing of ring currents related to the stacking of macrocycles. DFT ring-current shift calculations revealed that both chlorins self-assemble in antiparallel ?-stacks in planar layers in the solid-state. Concomitantly, X-ray powder diffraction measurements for chlorin 2 at 80 °C revealed a 3D lattice for the mesoscale packing that matches molecular mechanics optimized aggregate models. For chlorin 2 the stacks alternate with a periodicity of 0.68 nm and a 3D unit cell with an approximate volume of 6.28 nm3 containing 4 molecules, which is consistent with space group P21221.

Ganapathy, Swapna; Sengupta, Sanchita; Wawrzyniak, Piotr K.; Huber, Valerie; Buda, Francesco; Baumeister, Ute; Wurthner, Frank; de Groot, Huub J. M.

2009-01-01

61

Theory of fine structure of correlated exciton states in self-assembled semiconductor quantum dots in a magnetic field  

NASA Astrophysics Data System (ADS)

A theory of the fine structure of correlated exciton states in self-assembled parabolic semiconductor quantum dots in a magnetic field perpendicular to the quantum dot plane is presented. The correlated exciton wave function is expanded in configurations consisting of products of electron and heavy-hole 2D harmonic oscillator states (HO) in a magnetic field and the electron spin Sz=±1/2 and a heavy-hole spin ?z=±3/2 states. Analytical expressions for the short- and long-range electron-hole exchange Coulomb interaction matrix elements are derived in the HO and spin basis for arbitrary magnetic field. This allows the incorporation of short- and long-range electron-hole exchange, direct electron-hole interaction, and quantum dot anisotropy in the exact diagonalization of the exciton Hamiltonian. The fine structure of ground and excited correlated exciton states as a function of a number of confined shells, quantum dot anisotropy, and magnetic field is obtained using exact diagonalization of the many-body Hamiltonian. The effects of correlations are shown to significantly affect the energy splitting of the two bright exciton states.

Trojnar, Anna H.; Kadantsev, Eugene S.; Korkusi?ski, Marek; Hawrylak, Pawel

2011-12-01

62

A Solid-State Compressor for Integration of CO2 Removal and Reduction Assemblies  

NASA Technical Reports Server (NTRS)

Integration of CO2 removal and reduction assemblies in a spacecraft air revitalization system requires an interface with the functionality of a vacuum pump/compressor and a buffer tank. The compressor must meet the vacuum needs of the CO2 removal unit and the pressure needs of the CO2 reduction device, and must also store sufficient CO2 to accommodate the differences in cycle times of the two processes. In this presentation, we describe the design and operation of an adsorption-based device sized for use on the International Space Station. The adsorption compressor functions at a power level approximately ten times lower than a comparable mechanical compression/buffer tank system. The unit is also smaller, lighter, and quieter than its mechanical counterpart.

Mulloth, Lila M.; Finn, John E.; Lung, Bernadette (Technical Monitor)

2000-01-01

63

Two equations of state assembled for basic analysis of multiphase CO 2 flow and in deep sedimentary basin conditions  

NASA Astrophysics Data System (ADS)

The purpose of the study presented in this manuscript is to describe and make available two equation-of-state (EOS) algorithms assembled for multiphase flow and transport of carbon dioxide (CO 2). The algorithms presented here calculate solubility, compressibility factor, density, viscosity, fugacity, and enthalpy of CO 2 in gaseous and supercritical phases, and mixtures or solutions of CO 2 in water, as functions of pressure and temperature. Several features distinguish the two algorithms, but the primary distinction concerns treatment of supercritical/gas-phase CO 2: one EOS we assembled is based on Redlich and Kwong's original algorithm developed in 1949, and the other is based on an algorithm developed by Span and Wagner in 1996. Both were modified for application to sedimentary basin studies of multiphase CO 2 flow processes, including carbon sequestration applications. We present a brief comparison of these two EOS algorithms. Source codes for both algorithms are provided, including "stand-alone" Matlab scripts for the interactive calculation of fluid properties at specified P- T conditions and FORTRAN subroutines for inclusion in existing FORTRAN multiphase fluid simulation packages. These routines are intended for fundamental analyses of CO 2 sequestration and the like; more advanced studies, such as brine processes and reactive transport, require more advanced EOS algorithms.

McPherson, Brian J. O. L.; Han, Weon Shik; Cole, Barret S.

2008-05-01

64

Independent saturation of three TrpRS subsites generates a partially assembled state similar to those observed in molecular simulations  

PubMed Central

Two new crystal structures of Bacillus stearothermophilus tryptophanyl-tRNA synthetase (TrpRS) afford evidence that a closed interdomain hinge angle requires a covalent bond between AMP and an occupant of either pyrophosphate or tryptophan subsite. They also are within experimental error of a cluster of structures observed in a nonequilibrium molecular dynamics simulation showing partial active-site assembly. Further, the highest energy structure in a minimum action pathway computed by using elastic network models for Open and Pretransition state (PreTS) conformations for the fully liganded TrpRS monomer is intermediate between that simulated structure and a partially disassembled structure from a nonequilibrium molecular dynamics trajectory for the unliganded PreTS. These mutual consistencies provide unexpected validation of inferences drawn from molecular simulations.

Laowanapiban, Poramaet; Kapustina, Maryna; Vonrhein, Clemens; Delarue, Marc; Koehl, Patrice; Carter, Charles W.

2009-01-01

65

Image Potential States of Electrons Interacting with Roughened Metal Surfaces Coated with Self-Assembled Alkanethiol Monolayers  

NASA Astrophysics Data System (ADS)

Electrons in image potential states (IPS) [1] have been a topic of great interest at smooth dielectric/metal interfaces [2]. IPSs at roughened dielectric/metal interfaces have recently been reported [3]. The IPS model is extended to the case of a charge interacting with two intersecting metal planes. We discuss the role of the angle between intersecting metal planes (characteristic of roughened surfaces) on the IPS binding energies for electrons interacting with these structures. Our results are applied to roughened gold surfaces coated with self-assembled alkanethiol monolayers. [1] T. Fauster, Applied Phys. A 59, 479, 1994. [2] N.-H. Ge, C. M. Wong, R. L. Lingle, Jr., J. D. McNeill, K. J. Gaffney, and C. B. Harris, Science 279, 202, 1998, for example. [3] B. K. Clark, B. W. Gregory, A. Avila, T. M. Cotton, and J. M. Standard, J. Phys. Chem. B 103, 8201, 1999.

Clark, B. K.; Standard, J. M.; Gregory, Brian W.

2000-03-01

66

Independent saturation of three TrpRS subsites generates a partially assembled state similar to those observed in molecular simulations  

SciTech Connect

Two new crystal structures of Bacillus stearothermophilus tryptophanyl-tRNA synthetase (TrpRS) afford evidence that a closed interdomain hinge angle requires a covalent bond between AMP and an occupant of either pyrophosphate or tryptophan subsite. They also are within experimental error of a cluster of structures observed in a nonequilibrium molecular dynamics simulation showing partial active-site assembly. Further, the highest energy structure in a minimum action pathway computed by using elastic network models for Open and Pretransition state (PreTS) conformations for the fully liganded TrpRS monomer is intermediate between that simulated structure and a partially disassembled structure from a nonequilibrium molecular dynamics trajectory for the unliganded PreTS. These mutual consistencies provide unexpected validation of inferences drawn from molecular simulations.

Laowanapiban, Poramaet; Kapustina, Maryna; Vonrhein, Clemens; Delarue, Marc; Koehl, Patrice; Carter Jr., Charles W.; (Centre National de la Recherche Scientifique); (GPL); (UCD); (UNC)

2009-03-05

67

Laplace-Transform Deep-Level Spectroscopy Characterization of the Intrinsic and Deep-Level States in Self-Assembled InAs Quantum-Dot Structures  

SciTech Connect

The electron emission from the intrinsic and deep-level states in self-assembled InAs/GaAs quantum-dot structures is probed using the Laplace-transform deep-level transient spectroscopy. The technique shows sufficient resolution to resolve electron emission from the singly and doubly occupied QD s states. By applying an appropriate set of voltage pulses across the Schottky-diode structure, we identify the electron distribution profile in the quantum-dot intrinsic states.

Lin, S. W. [School of Electrical and Electronic Engineering, University of Manchester, Manchester M60 1QD (United Kingdom); School of Materials Science and Chemical Engineering, Hainan University, Haikou 570228 (China); Song, A. M.; Peaker, A. R. [School of Materials Science and Chemical Engineering, Hainan University, Haikou 570228 (China)

2010-01-04

68

Subunit Conformations and Assembly States of a DNA Translocating Motor: The Terminase of Bacteriophage P22  

PubMed Central

Bacteriophage P22, a podovirus infecting strains of Salmonella typhimurium, packages a 42 kbp genome using a headful mechanism. DNA translocation is accomplished by the phage terminase, a powerful molecular motor consisting of large and small subunits. Although many of the structural proteins of the P22 virion have been well characterized, little is known about the terminase subunits and their molecular mechanism of DNA translocation. We report here structural and assembly properties of ectopically expressed and highly purified terminase large and small subunits. The large subunit (gp2), which contains the nuclease and ATPase activities of terminase, exists as a stable monomer with an ?/? fold. The small subunit (gp3), which recognizes DNA for packaging and may regulate gp2 activity, exhibits a highly ?-helical secondary structure and self-associates to form a stable oligomeric ring in solution. For wildtype gp3, the ring contains nine subunits, as demonstrated by hydrodynamic measurements, electron microscopy and native mass spectrometry. We have also characterized a gp3 mutant (Ala 112 ? Thr) that forms a ten subunit ring, despite a subunit fold indistinguishable from wildtype. Both the nonameric and decameric gp3 rings exhibit nonspecific DNA binding activity, and gp2 is able to bind strongly to the DNA/gp3 complex but not to DNA alone. We propose a scheme for the roles of P22 terminase large and small subunits in the recruitment and packaging of viral DNA and discuss the model in relation to proposals for terminase-driven DNA translocation in other phages.

Nemecek, Daniel; Gilcrease, Eddie B.; Kang, Sebyung; Prevelige, Peter E.; Casjens, Sherwood; Thomas, George J.

2007-01-01

69

Preparation and characterisation of novel chlorothiazide potassium solid-state salt forms: Intermolecular self assembly suprastructures.  

PubMed

Chlorothiazide (CTZ) is a poorly soluble diuretic agent. The aim of the present work was to produce and characterise a potassium salt form of chlorothiazide which has the potential advantages of improved aqueous solubility and potassium supplementation. A number of novel potassium salt forms of CTZ (CTZK) were prepared: CTZK monohydrate (form I), CTZK dihydrate (form II), anhydrous CTZK (form III), CTZK monohydrate hemiethanolate (form IV) and a desolvate of CTZK monohydrate hemiethanolate (form V). These salt forms were characterised by thermal analysis, PXRD, NMR, elemental analysis, FTIR, Karl Fisher titrimetry, ICP-MS and GC-MS. The ethanol-free CTZK forms were also characterised by dynamic vapour sorption analysis (DVS). CTZK form I was stable (in the DVS) over the range 0-60% RH. The dihydrate form of the salt was stable (in the DVS) over a broader range of relative humidities, 10-90% RH at 25°C. CTZK form II was less hygroscopic at high humidities (70-90% RH) than the previously reported CTZNa dihydrate. Single crystal X-ray analysis indicated that chlorothiazide potassium, crystallised from water or water/acetone mixture, formed a dihydrated polymeric-like intermolecular self-assembly (ISA) suprastructure. The ISA coordination was determined to be: (CTZ)(3)·K·(H(2)O)(2)(CTZ)(2)·(H(2)O)(2)·K·(CTZ)(3) (monoclinic, space group: C2/c, single crystal cell parameters: a=18.328(4)?, b=7.3662(16)?, c=19.993(5)?, ?=90°, ?=99.729(3)°, ?=90°). When CTZK was crystallised from ethanol, a monohydrate hemiethanolate ISA was formed, described as (CTZ)(3)·K·CTZ·(H(2)O)(2)·CTZ·K·(CTZ)(2) (triclinic, space group: P-1, single crystal cell parameters: a=7.078(3)?, b=9.842(5)?, c=21.994(11)?, ?=87.522(13)°, ?=84.064(14)°, ?=78.822(12)°). The aqueous solubility of CTZK dihydrate, was determined to be 78.71±1.82mg/ml, approximately 400-fold higher than chlorothiazide, indicating a biopharmaceutical advantage associated with the potassium salt form. PMID:21115114

Paluch, Krzysztof J; Tajber, Lidia; McCabe, Thomas; O'Brien, John E; Corrigan, Owen I; Healy, Anne Marie

2011-02-14

70

Out-of-equilibrium dynamics in superspin glass state of strongly interacting magnetic nanoparticle assemblies  

NASA Astrophysics Data System (ADS)

Interacting magnetic nanoparticles display a wide variety of magnetic behaviors ranging from modified superparamagnetism, superspin glass to possibly, superferromagnetism. The superspin glass state is described by its slow and out-of-equilibrium magnetic behaviors akin to those found in atomic spin glasses. In this article, recent experimental findings on superspin correlation length growth and the violation of the fluctuation-dissipation theorem obtained in concentrated frozen ferrofluids are presented to illustrate certain out-of-equilibrium dynamics behavior in superspin glasses.

Nakamae, Sawako

2014-04-01

71

Neurodegeneration Induced by ,&Amyloid Peptides in vi&o: The Role of Peptide Assembly State  

Microsoft Academic Search

The progressive neurodegeneration of Alzheimer's disease has been hypothesized to be mediated, at least in part, by D-amyloid protein. A relationship between the aggregation state of B-amyloid protein and its ability to promote degen- eration in vitro has been previously suggested. To evaluate this hypothesis and to define a structure-activity relation- ship for \\/3-amyloid, aggregation properties of an overlapping series

Christian J. Pike; Debra Burdick; Andrea J. Walencewicz; Charles G. Glabe; Carl W. Cotman

1993-01-01

72

Effects of self-assembled monolayers on solid-state CdS quantum dot sensitized solar cells.  

PubMed

Quantum dot sensitized solar cells (QDSSCs) are of interest for solar energy conversion because of their tunable band gap and promise of stable, low-cost performance. We have investigated the effects of self-assembled monolayers (SAMs) with phosphonic acid headgroups on the bonding and performance of cadmium sulfide (CdS) solid-state QDSSCs. CdS quantum dots ?2 to ?6 nm in diameter were grown on SAM-passivated planar or nanostructured TiO(2) surfaces by successive ionic layer adsorption and reaction (SILAR), and photovoltaic devices were fabricated with spiro-OMeTAD as the solid-state hole conductor. X-ray photoelectron spectroscopy, Auger electron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, water contact angle measurements, ellipsometry, and electrical measurements were employed to characterize the materials and the resulting device performance. The data indicate that the nature of the SAM tailgroup does not significantly affect the uptake of CdS quantum dots on TiO(2) nor their optical properties, but the presence of the SAM does have a significant effect on the photovoltaic device performance. Interestingly, we observe up to ?3 times higher power conversion efficiencies in devices with a SAM compared to those without the SAM. PMID:21299223

Ardalan, Pendar; Brennan, Thomas P; Lee, Han-Bo-Ram; Bakke, Jonathan R; Ding, I-Kang; McGehee, Michael D; Bent, Stacey F

2011-02-22

73

Many-body exciton states in self-assembled quantum dots coupled to a Fermi sea  

NASA Astrophysics Data System (ADS)

Many-body interactions give rise to fascinating physics such as the X-ray Fermi-edge singularity in metals, the Kondo effect in the resistance of metals with magnetic impurities and the fractional quantum Hall effect. Here we report the observation of striking many-body effects in the optical spectra of a semiconductor quantum dot interacting with a degenerate electron gas. A semiconductor quantum dot is an artificial atom, the properties of which can be controlled by means of a tunnel coupling between a metallic contact and the quantum dot. Previous studies concern mostly the regime of weak tunnel coupling, whereas here we investigate the regime of strong coupling, which markedly modifies the optical spectra. In particular we observe two many-body exciton states: Mahan and hybrid excitons. These experimental results open the route towards the observation of a tunable Kondo effect in excited states of semiconductors and are of importance for the technological implementation of quantum dots in devices for quantum information processing.

Kleemans, N. A. J. M.; van Bree, J.; Govorov, A. O.; Keizer, J. G.; Hamhuis, G. J.; Nötzel, R.; Silov, A. Yu.; Koenraad, P. M.

2010-07-01

74

State-of-the-art silicon carbide optical telescope assembly for the JMAPS mission  

NASA Astrophysics Data System (ADS)

L-3 Communications IOS-SSG (L-3 SSG) has recently completed development of an ultra low wavefront error and highly stable Silicon Carbide (SiC) optical payload for the Joint Milli-Arcsecond Pathfinder Survey (JMAPS) mission. Selection of SiC as the opto-mechanical material was driven by the JMAPS requirements for extremely low residual optical aberrations and distortion, and state-of-the-art temporal and thermal stability. JMAPS utilizes a passively athermalized design, combining SiC optics with aggressively lightweighted SiC metering structures. The resulting hardware has been optically tested over temperature, demonstrating an exceptionally low and stable system level wavefront error. This exceptional performance, combined with the aggressively lightweighted sinterbonded SiC structures developed result in an instrument which represents the state-of-the-art from the perspective of optical performance and structural efficiency. We will provide an overview of the system, with emphasis on the SiC opto-mechanics, and system level test results.

Catropa, Dan; Azad, Farsh

2013-09-01

75

Process development and prototyping for the assembly of LED arrays on flexible printed circuit tape for general solid state lighting  

Microsoft Academic Search

The objective of the present study is to develop a robust high-throughput assembly process of light emitting diode arrays for wide area general lighting. Topics to be covered in this paper include the conceptual design, the flexible printed circuit substrate, flip chip assembly, yellow phosphor coating, and encapsulation. All these are integrated into one reel-to-reel assembly process. A prototype with

S. W. Ricky Lee; Y. W. Tong; Y. S. Chan; J. C. C. Lo; R. Zhang

2009-01-01

76

Self-assembly of liquid crystal block copolymer PEG-b-smectic polymer in pure state and in dilute aqueous solution  

Microsoft Academic Search

A series of amphiphilic LC block copolymers, in which the hydrophobic block is a smectic polymer poly(4-methoxyphenyl 4-(6-acryloyloxy-hexyloxy)-benzoate) (PA6ester1) and the hydrophilic block is polyethyleneglycol (PEG), were synthesized and characterized. The self-assembly of one of them in both the pure state and the dilute aqueous solution was investigated in detail. Nano-structures in the pure state were studied by SAXS and

Bing Xu; Rafael Piñol; Merveille Nono-Djamen; Sandrine Pensec; Patrick Keller; Pierre-Antoine Albouy; Daniel Lévy; Min-Hui Li

2009-01-01

77

Hole states in Ge/Si quantum-dot molecules produced by strain-driven self-assembly  

NASA Astrophysics Data System (ADS)

Space-charge spectroscopy was employed to study hole emission from the confined states in vertically self-aligned double Ge quantum dots separated by a Si barrier. From the temperature- and frequency-dependent measurements, the hole binding energy was determined as a function of the separation between the dots, tSi. Increasing of the ground state hole energy due to formation of a bonding molecular orbital was found to be as large as ~50 meV at tSi=1.5 nm. For a dot layer separation exceeding 3 nm, the hole binding energy in double-dot molecule becomes smaller than the ionization energy of the single Ge dot, contrasting with a simplified quantum-mechanical molecular model. To analyze the experiment the electronic structure of two vertically coupled pyramidal Ge quantum dots embedded in Si was investigated by a nearest neighbor tight-binding single-particle Hamiltonian with the sp3 basis. The elastic strain due to the lattice mismatch between Ge and Si was included into the problem. The three-dimensional spatial strain distribution was found in terms of atomic positions using a valence-force-field theory with a Keating interatomic potential. It was demonstrated that formation of single-particle hole states in self-organized molecules is governed by the interplay among two effects. The first is the quantum-mechanical coupling between the individual states of two dots constituting the molecule. The second one originates from asymmetry of the strain field distribution within the top and bottom dots due to the lack of inversion symmetry with respect to the medium plane between the dots. Analysis of the biaxial strain distribution showed that anomalous decreasing of the hole binding energy below the value of the single dot with increasing interdot separation is caused by the partial strain relaxation upon dot stacking accompanied by the strain-induced reduction of the hole confinement potential. We found that the molecule-type hole state delocalized fairly over the two dots is formed only at tSi<3.3 nm and at tSi>3.8 nm. For the intermediate distances (3.3 nm<=tSi<=3.8 nm), the hole becomes confined mostly inside the bottom, most strained Ge dot. The overall agreement between theory and experiment turns out to be quite good, indicating the crucial role played by strain fields in electronic coupling of self-assembled quantum-dot molecules.

Yakimov, A. I.; Mikhalyov, G. Yu.; Dvurechenskii, A. V.; Nikiforov, A. I.

2007-11-01

78

Benzene on Cu(111): II. Molecular assembly due to Lateral van der Waals and Surface-State-Mediated Indirect Interactions  

NASA Astrophysics Data System (ADS)

Experiments show that benzene condenses into two different structural phases: a compact and a sparse phase, both of approximately hexagonal symmetry. The vdW-DF calculations demonstrate that the denser benzene-overlayer phase, with lattice constant 6.74 ,s due to direct benzene-benzene vdW attraction. The structure of the second, sparser phase, with lattice spacing 10.24 ,s attributed to the indirect electronic interactions mediated by the well-known metallic surface state on Cu(111). To support this claim, we use a formal Harris-functional approach to evaluate nonperturbatively the asymptotic form of this indirect interaction. Our extended vdW-DF scheme---which combines calculations of molecular physisorption, of direct intermolecular vdW coupling, and of indirect electronic interactions between the molecular adsorbates---accounts well for the structural phases of benzene on Cu(111). Our preliminary vdW-DF study of acene and quinone interactions provides building blocks for modeling of anthraquinone assembly on Cu(111).footnotetextG. Pawin, , L. Bartels, Science 313 (2006) 961

Hyldgaard, Per; Berland, Kristian; Einstein, T. L.

2010-03-01

79

In situ assembly states of (Na+,K+)-pump ATPase in human erythrocytes. Radiation target size analyses  

SciTech Connect

The in situ assembly state of the (Na+,K+)-pump ATPase of human erythrocytes was studied by applying the classical target theory to radiation inactivation data of the ouabain-sensitive sodium efflux and ATP hydrolysis. Erythrocytes and their extensively washed white ghosts were irradiated at -45 to -50 degrees C with an increasing dose of 1.5-MeV electron beam, and after thawing, the Na+-pump flux and/or enzyme activities were assayed. Each activity measured was reduced as a simple exponential function of radiation dose, from which a radiation sensitive mass (target size) was calculated. When intact cells were used, the target sizes for the pump and for the ATPase activities were equal and approximately 620,000 daltons. The target size for the ATPase activity was reduced to approximately 320,000 daltons if the cells were pretreated with digitoxigenin. When ghosts were used, the target size for the ATPase activity was again approximately 320,000 daltons. Our target size measurements together with other information available in literature suggest that (Na+,K+)-pump ATPase may exist in human erythrocytes either as a tetramer of alpha beta or as a dimer of alpha beta in tight association with other protein mass, probably certain glycolytic enzymes, and that this tetrameric or heterocomplex association is dissociable by digitoxigenin treatment or by extensive wash during ghost preparation.

Hah, J.; Goldinger, J.M.; Jung, C.Y.

1985-11-15

80

Structures of S. pombe phosphofructokinase in the F6P-bound and ATP-bound states  

PubMed Central

Phosphofructokinase (Pfk1; EC 2.7.1.11) is the third enzyme of the glycolytic pathway catalyzing the formation of fructose-1,6-bisphosphate from fructose-6-phosphate (F6P) and ATP. Schizosaccharomyces pombe Pfk1 is a homo-octameric enzyme of 800 kDa molecular weight, distinct from its yeast counterparts which are mostly hetero-octameric enzymes composed of two different subunits. Having an “open” conformation and a tendency to aggregate into higher oligomeric structures, the S. pombe enzyme shows similarities to the mammalian muscle Pfk1. It has been proposed that due to the distinct N-terminal region of the S. pombe subunit, the oligomeric organization of subunits in this enzyme is different from other yeast phosphofructokinases. Electron microscopy studies were carried out to reveal the quaternary structure of the homo-octameric Pfk1 from S. pombe in the F6P-bound and in the ATP-bound state. Random conical tilt data sets have been collected from deep stain preparations of the enzyme in both states. The 0° tilt images have been separated into different classes and a 3D reconstruction has been calculated for each class from the high tilt images. Our results confirm the presence of a variety of views of the particle, most of which can be interpreted as views of the molecule rotating around its long axis. Despite the biochemical differences, the structure of phosphofructokinase from S. pombe in the presence of either F6P or ATP is similar to the hetero-octameric structure of phosphofructokinase from Saccharomyces cerevisiae. The molecule can be described as composed of two subdomains, connected by two well-defined densities. We have been able to establish a correlation between the kinetic behavior and the structural conformation of Pfk1.

Benjamin, Shaun; Radermacher, Michael; Bar, Jorg; Edelmann, Anke; Ruiz, Teresa

2009-01-01

81

Measuring deuteron beam parameters with solid-state track detectors in experiments with the QUINTA target assembly  

NASA Astrophysics Data System (ADS)

The results of measurements of the beam parameters on the target upon irradiation of the QUINTA subcritical uranium assembly with deuterons with energies of 1, 4, and 8 GeV are presented. Data on the position of the incident particle beam relative to the assembly axis and on the actual geometric parameters of the beam make it possible to analyze information on the spatial distributions of reaction rates within the target assembly correctly, comparing such distributions obtained at different irradiation sessions and modeling the experiments with the use of MCNPX, GEANT4, FLUKA, and other similar software tools.

Artyushenko, M. Yu.; Voronko, V. A.; Gusak, K. V.; Zhuk, I. V.; Kadykov, M. G.; Potapenko, A. S.; Safronova, A. A.; Sotnikov, V. V.; Tyutyunnikov, S. I.; Furman, V. I.; Chilap, V. V.; Chinenov, A. V.

2013-11-01

82

Two forms and two faces, multiple states and multiple uses: Properties and applications of the self-assembling fungal hydrophobins.  

PubMed

The fungal hydrophobins are small proteins that are able to spontaneously self-assemble into amphipathic monolayers at hydrophobic:hydrophilic interfaces. These protein monolayers can reverse the wettability of a surface, making them suitable for increasing the biocompatibility of many hydrophobic materials. The self-assembling properties and amphipathic nature of hydrophobins make them attractive candidates for biotechnological applications. Recently, there have been significant advances in the understanding of the structure and assembly of these remarkable proteins. This opens up the way for engineering these proteins to encompass novel functions and for the use of hydrophobins in modification of nanomaterials. This review highlights the important structural aspects of the hydrophobins and the mechanisms by which they assemble and describes recent exciting developments in the use of hydrophobins for cell attachment, drug delivery, and protein purification. © 2013 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 601-612, 2013. PMID:23913717

Ren, Qin; Kwan, Ann H; Sunde, Margaret

2013-11-01

83

Macintosh assembly language  

Microsoft Academic Search

The purpose of this talk is to present a progress report on the conversion of the teaching of assembly language at Ohio State from the IBM System\\/370 mainframe to the Apple Macintosh microcomputer. An earlier report on this subject appears in the proceedings of the 1987 Computer Science Conference.Pilot sections on Macintosh assembly language were first taught in Winter and

Clinton R. Foulk

1988-01-01

84

Investigation of the local density of states in self-assembled GeSi/Si(001) nanoislands by combined scanning tunneling and atomic-force microscopy  

SciTech Connect

The local density of states in self-assembled GeSi/Si(001) nanoislands is investigated for the first time by combined tunneling and atomic-force scanning microscopy. Current images and tunneling spectra of individual GeSi/Si(001) islands are obtained. These measurements yield the spatial and energy distributions of the local density of states in GeSi islands, respectively. The tunneling spectroscopy data demonstrate that uncapped Ge{sub 0.3}Si{sub 0.7}/Si(001) islands behave as type-I heterostructures.

Borodin, P. A.; Bukharaev, A. A. [Russian Academy of Sciences, Zavoisky Physical Technical Institute, Kazan Scientific Center (Russian Federation); Filatov, D. O., E-mail: dmitry_filatov@inbox.ru; Isakov, M. A.; Shengurov, V. G.; Chalkov, V. Yu.; Denisov, Yu. A. [Lobachevsky State University, Research Institute for Physics and Technology (Russian Federation)

2011-03-15

85

RNA polymerase II subunits exhibit a broad distribution of macromolecular assembly states in the interchromatin space of cell nuclei.  

PubMed

Nearly all cellular processes are enacted by multi-subunit protein complexes, yet the assembly mechanism of most complexes is not well understood. The anthropomorphism "protein recruitment" that is used to describe the concerted binding of proteins to accomplish a specific function conceals significant uncertainty about the underlying physical phenomena and chemical interactions governing the formation of macromolecular complexes. We address this deficiency by investigating the diffusion dynamics of two RNA polymerase II subunits, Rpb3 and Rpb9, in regions of live Drosophila cell nuclei that are devoid of chromatin binding sites. Using FRAP microscopy, we demonstrate that both unengaged subunits are incorporated into a broad distribution of complexes, with sizes ranging from free (unincorporated) proteins to those that have been predicted for fully assembled gene transcription units. In live cells, Rpb3 exhibits regions of stability at both size extremes connected by a continuous distribution of complexes. Corresponding measurements on cellular extracts reveal a distribution that retains peaks at the extremes but not in between, suggesting that partially assembled complexes are less stable. We propose that the broad distribution of macromolecular species allows for mechanistic flexibility in the assembly of transcription complexes. PMID:24354435

Tycon, Michael A; Daddysman, Matthew K; Fecko, Christopher J

2014-01-16

86

Analysis of the structure and conformational states of DewA gives insight into the assembly of the fungal hydrophobins.  

PubMed

The hydrophobin DewA from the fungus Aspergillus nidulans is a highly surface-active protein that spontaneously self-assembles into amphipathic monolayers at hydrophobic:hydrophilic interfaces. These monolayers are composed of fibrils that are a form of functional amyloid. While there has been significant interest in the use of DewA for a variety of surface coatings and as an emulsifier in biotechnological applications, little is understood about the structure of the protein or the mechanism of self-assembly. We have solved the solution NMR structure of DewA. While the pattern of four disulfide bonds that is a defining feature of hydrophobins is conserved, the arrangement and composition of secondary-structure elements in DewA are quite different to what has been observed in other hydrophobin structures. In addition, we demonstrate that DewA populates two conformations in solution, both of which are assembly competent. One conformer forms a dimer at high concentrations, but this dimer is off-pathway to fibril formation and may represent an assembly control mechanism. These data highlight the structural differences between fibril-forming hydrophobins and those that form amorphous monolayers. This work will open up new opportunities for the engineering of hydrophobins with novel biotechnological applications. PMID:23137797

Morris, Vanessa K; Kwan, Ann H; Sunde, Margaret

2013-01-23

87

Silencing and Languaging in the Assembling of the Indian Nation-State: British Public Citizens, the Epistolary Form, and Historiography  

ERIC Educational Resources Information Center

Taking the case of postcolonial India, this paper explores ways in which present temporal junctures permit a probing of historical boundaries to speak of voices largely silenced from Indian historiography, namely those of British (Indian) public citizens who were committed to the assembling of "an India." In particular, the paper discusses ways in…

Ramanathan, Vaidehi

2009-01-01

88

d(CGGTGGT) forms an octameric parallel G-quadruplex via stacking of unusual G(:C):G(:C):G(:C):G(:C) octads  

PubMed Central

Among non-canonical DNA secondary structures, G-quadruplexes are currently widely studied because of their probable involvement in many pivotal biological roles, and for their potential use in nanotechnology. The overall quadruplex scaffold can exhibit several morphologies through intramolecular or intermolecular organization of G-rich oligodeoxyribonucleic acid strands. In particular, several G-rich strands can form higher order assemblies by multimerization between several G-quadruplex units. Here, we report on the identification of a novel dimerization pathway. Our Nuclear magnetic resonance, circular dichroism, UV, gel electrophoresis and mass spectrometry studies on the DNA sequence dCGGTGGT demonstrate that this sequence forms an octamer when annealed in presence of K+ or NH4+ ions, through the 5?-5? stacking of two tetramolecular G-quadruplex subunits via unusual G(:C):G(:C):G(:C):G(:C) octads.

Borbone, Nicola; Amato, Jussara; Oliviero, Giorgia; D'Atri, Valentina; Gabelica, Valerie; De Pauw, Edwin; Piccialli, Gennaro; Mayol, Luciano

2011-01-01

89

Engineering solid-state materials. Strategies for modeling and packing control of molecular assemblies into 3-D networks  

NASA Astrophysics Data System (ADS)

The crystal structure and properties of a number of urea cocrystals are studied with regard to symmetry of the hydrogen-bonded molecular assemblies. The logical consequences of hydrogen bonding interactions are followed step-by-step. The problems of aggregate formation, nucleation, and crystal growth are also elucidated. Endeavor is made to envisage the 2-D and 3-D hydrogen bond network in a manageable way by exploiting graph set short hand. Strategies of how to control the symmetry of molecular packing are still to be elaborated. In our strategy, the programmed self-assembly has been based on the principle of molecular recognition of self- and hetero-complementary functional groups. However, the main focus for pre-organizational control has been put on the two-fold axis estimator of the urea molecule.

Videnova-Adrabinska, V.; Etter, M. C.; Ward, M. D.

1993-04-01

90

Monitoring the effect of subunit assembly on the structural flexibility of human alpha apohemoglobin by steady-state fluorescence  

Microsoft Academic Search

A single energy transfer distance, between the sole intrinsic tryptophanyl donor [14 (A12)] and a nonfluorescent sulfhydryl acceptor probe (4-phenylazophenylmaleimide, PAPM) attached to the only cysteine [104 (G11)], has been employed to examine the effect of subunit assembly on the structure of the heme-free humana-hemoglobin. Efficiencies of energy transfer were measured in 0.05 M potassium phosphate buffer,pH 7.0, at 5°C,

Shawn M. O'Malley; Melisenda J. McDonald

1994-01-01

91

Neural assembly computing.  

PubMed

Spiking neurons can realize several computational operations when firing cooperatively. This is a prevalent notion, although the mechanisms are not yet understood. A way by which neural assemblies compute is proposed in this paper. It is shown how neural coalitions represent things (and world states), memorize them, and control their hierarchical relations in order to perform algorithms. It is described how neural groups perform statistic logic functions as they form assemblies. Neural coalitions can reverberate, becoming bistable loops. Such bistable neural assemblies become short- or long-term memories that represent the event that triggers them. In addition, assemblies can branch and dismantle other neural groups generating new events that trigger other coalitions. Hence, such capabilities and the interaction among assemblies allow neural networks to create and control hierarchical cascades of causal activities, giving rise to parallel algorithms. Computing and algorithms are used here as in a nonstandard computation approach. In this sense, neural assembly computing (NAC) can be seen as a new class of spiking neural network machines. NAC can explain the following points: 1) how neuron groups represent things and states; 2) how they retain binary states in memories that do not require any plasticity mechanism; and 3) how branching, disbanding, and interaction among assemblies may result in algorithms and behavioral responses. Simulations were carried out and the results are in agreement with the hypothesis presented. A MATLAB code is available as a supplementary material. PMID:24806763

Ranhel, João

2012-06-01

92

Bacteriophage Assembly  

PubMed Central

Bacteriophages have been a model system to study assembly processes for over half a century. Formation of infectious phage particles involves specific protein-protein and protein-nucleic acid interactions, as well as large conformational changes of assembly precursors. The sequence and molecular mechanisms of phage assembly have been elucidated by a variety of methods. Differences and similarities of assembly processes in several different groups of bacteriophages are discussed in this review. The general principles of phage assembly are applicable to many macromolecular complexes.

Aksyuk, Anastasia A.; Rossmann, Michael G.

2011-01-01

93

LptE binds to and alters the physical state of LPS to catalyze its assembly at the cell surface.  

PubMed

The assembly of lipopolysaccharide (LPS) on the surface of Gram-negative bacterial cells is essential for their viability and is achieved by the seven-protein LPS transport (Lpt) pathway. The outer membrane (OM) lipoprotein LptE and the ?-barrel membrane protein LptD form a complex that assembles LPS into the outer leaflet of the OM. We report a crystal structure of the Escherichia coli OM lipoprotein LptE at 2.34 Å. The structure reveals homology to eukaryotic LPS-binding proteins and allowed for the prediction of an LPS-binding site, which was confirmed by genetic and biophysical experiments. Specific point mutations at this site lead to defects in OM biogenesis. We show that wild-type LptE disrupts LPS-LPS interactions in vitro and that these mutations decrease the ability of LptE to disaggregate LPS. Transmission electron microscopic imaging shows that LptE can disrupt LPS aggregates even at substoichiometric concentrations. We propose a model in which LptE functions as an LPS transfer protein in the OM translocon by disaggregating LPS during transport to allow for its insertion into the OM. PMID:24938785

Maloj?i?, Goran; Andres, Dorothee; Grabowicz, Marcin; George, Alexander H; Ruiz, Natividad; Silhavy, Thomas J; Kahne, Daniel

2014-07-01

94

Preliminary Experiments and Determination of the Thermal Gradient in a 12.7 mm CaF2 Furnace Assembly, Humboldt State University Piston-Cylinder Laboratory  

NASA Astrophysics Data System (ADS)

A 12.7 mm piston-cylinder laboratory has been established at Humboldt State University. A series of double-thermocouple (DTC) experiments were performed to measure the thermal profile of the furnace assembly following the procedures of Pickering et al. (1998, Amer. Min.). Furnace assemblies consist of a 304 stainless base plug, CaF&_{2} sleeve, straight-walled graphite heater tube, crushable MgO inner parts, and lower graphite plug and ring which allow for extrusion of the graphite heater tube during shortening of the sleeve and MgO pieces. Careful measurement of pre- and post-run assembly parts indicate an average 30-35% shortening of the assembly. DTC results show a thermal peak that is displaced \\sim2.0 mm above the center of the effective furnace, defined as the length of inner MgO pieces post-run. This offset is in the same direction (upward, toward base plug), but slightly less than the offset described by Pickering et al. (1998). A secondary measure of the thermal profile using spinel growth via reaction between MgO and Al_{2}O_{3} assembly parts (e.g., Watson et al., 2002, CMP) is underway. A single partial melting experiment was performed at 1.0 GPa and 1330\\degC for 72 hours using intermediate peridotite starting material INT-A in a graphite-lined Pt capsule with vitreous carbon spheres as a melt sink. Phase compositions were determined by electron microprobe and mass balance calculations were made to determine melt fraction and mineral mode. Initial calculations yield glass:olivine:cpx:opx:spinel proportions of: 5.0:54.2:15.9:23.9:1.1. These preliminary results correspond well with previous work performed at the University of Oregon on the same starting material (Schwab and Johnston, 2001). The best match is with a 1315\\degC experiment (INT-A13) in terms of mode (6.9:53.7:13.4:25.0:1.0) and glass composition, indicating that the temperature of this initial experiment may be slightly cooler than the target temperature, however the results of this interlaboratory comparison are still within the \\pm10-15\\deg$C temperature uncertainty of the piston cylinder apparatus. Additional calibration experiments are ongoing.

Schwab, B. E.

2004-12-01

95

Impact of wetting-layer density of states on the carrier relaxation process in low indium content self-assembled (In,Ga)As/GaAs quantum dots  

NASA Astrophysics Data System (ADS)

Carrier relaxation processes have been studied in low indium content self-assembled (In,Ga)As/GaAs quantum dots (QDs). Temperature-dependent photoluminescence of the wetting layer (WL) and QDs, and QD photoluminescence rise time elongation from ˜100 to ˜200 ps in the range of 10-45 K, indicated a complex carrier relaxation scheme. It involves localization of carriers/excitons in the WL, their temperature-mediated release, and subsequent transfer between the states of the WL and QD ensemble. These observations are explained by a thermal hopping model, in which electron-hole pairs are redistributed within two separate sets of zero-dimensional states of considerably different densities connected by a two-dimensional mobility channel.

Syperek, M.; Baranowski, M.; S?k, G.; Misiewicz, J.; Löffler, A.; Höfling, S.; Reitzenstein, S.; Kamp, M.; Forchel, A.

2013-03-01

96

Designing Assemblies  

Microsoft Academic Search

.  \\u000a \\u000a This paper presents a theory to support the design of assemblies. It brings together prior work in a new synthesis, resulting\\u000a in a top-down process for designing assemblies so that they deliver geometric Key Characteristics (KCs) that achieve top level\\u000a customer requirements. The theory applies to assemblies that take the form of mechanisms (e.g. engines) or structures (e.g.\\u000a aircraft

D. E. Whitney; R. Mantripragada; J. D. Adams; S. J. Rhee

1999-01-01

97

Fabrication and transfer assembly of microscale, solid-state light emitting diodes and solar cells for transparent and flexible electronics applications  

NASA Astrophysics Data System (ADS)

Efficiency metrics for some solid-state electronic materials systems have progressed to the point where theoretical limits are being approached. Gallium nitride-based lightemitting diodes and silicon solar cells, for example, have achieved such extraordinarily high performance metrics that only incremental improvements upon them are expected in the next decade of intense research. This pseudo-plateau in performance development means concentrated effort can now be placed on strategic implementation of these materials into platforms that fill a growing demand for high-performance consumer products. Such products have traditionally relied upon large-scale materials, but possibilities now exist for manipulating micro-scale, wafer-based devices in ways that promote improvements in areas of electrical current spreading, light absorption and extraction, and thermal management. To this end, my research has focused on routes to fabricating and assembling solid-state light-emitting diodes and solar cells of indium gallium nitride and single-crystalline silicon, respectively, in configurations which optimize characteristics of their performance. Specifically, I have worked, in collaboration with others, to achieve a processing strategy that creates dense arrays of indium gallium nitride light-emitting diodes on a silicon wafer of (111) orientation and assemble them onto transparent and flexible substrates. This work produced novel form factors for solid-state lighting where small, light-emitting devices were spatially distributed and integrated with color-converting phosphors in ways that controllably tuned their chromaticity. We also demonstrated that incredible passive heat dissipation with these micro-scale elements stemming naturally from their small size and integration with metal films serving dually as an electrically interconnecting medium. The cell design and etching strategies used were then transferred to a single-crystalline silicon system where small, ribbon-like solar cells were fabricated. This work improved upon previous studies creating similar devices by increasing critical solar cell performance metrics. The developed solar cell structure utilizes a highly robust manufacturing layer of thermally-grown silicon dioxide which naturally doubles as an anti-reflection and passivation layer. Other improvements to previous performance metrics comes from optimized cell assembly onto structures that recycle and redistribute incident irradiation.

Brueckner, Eric P.

98

Expansion of nanosized pores in low-crystallinity nanoparticle-assembled plates via a thermally induced increase in solid-state density.  

PubMed

We investigated thermally induced changes in a low-crystallinity hydroxyapatite (HAp)-nanoparticle-assembled plate containing nanosized pores. We first prepared an aqueous dispersion of low-crystallinity HAp nanoparticles (particle size, 48 nm) via a wet chemical process and then prepared the nanoparticle-assembled plate by drying the dispersion on an oil substrate to prevent crack formation. Before the plates were subjected to heat treatments, they contained 7.9-nm-sized pores because of the gap between the nanoparticles, and their porosity was 60%. After the heat treatments (600-1100 °C) were performed for 1 h, the solid-state density determined using helium pycnometry increased from 2.85 to 3.21 g/cm(3), and the pore size increased from 7.9 to 250 nm. These results indicate that the pore size expanded because of increases in crystallinity and density, despite the large decrease in the total volume because of thermally induced sintering of the nanoparticles. PMID:23777865

Okada, Masahiro; Fujiwara, Keiko; Uehira, Mayo; Matsumoto, Naoyuki; Takeda, Shoji

2013-09-01

99

Geometric reasoning about assembly tools  

SciTech Connect

Planning for assembly requires reasoning about various tools used by humans, robots, or other automation to manipulate, attach, and test parts and subassemblies. This paper presents a general framework to represent and reason about geometric accessibility issues for a wide variety of such assembly tools. Central to the framework is a use volume encoding a minimum space that must be free in an assembly state to apply a given tool, and placement constraints on where that volume must be placed relative to the parts on which the tool acts. Determining whether a tool can be applied in a given assembly state is then reduced to an instance of the FINDPLACE problem. In addition, the author presents more efficient methods to integrate the framework into assembly planning. For tools that are applied either before or after their target parts are mated, one method pre-processes a single tool application for all possible states of assembly of a product in polynomial time, reducing all later state-tool queries to evaluations of a simple expression. For tools applied after their target parts are mated, a complementary method guarantees polynomial-time assembly planning. The author presents a wide variety of tools that can be described adequately using the approach, and surveys tool catalogs to determine coverage of standard tools. Finally, the author describes an implementation of the approach in an assembly planning system and experiments with a library of over one hundred manual and robotic tools and several complex assemblies.

Wilson, R.H.

1997-01-01

100

Molecular Recognition in the Solid State Controlled Assembly of Hydrogen-Bonded Molecular Sheets. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

A novel hydrogen bonding motif for the control of solid state structures has been developed. The motif is based on the hydrogen bonding complementarity of carboxylic acids with 2-aminopyridine derivatives. Linking two aminopyridine groups through a rigid ...

F. Garcia-Tellado S. J. Geib S. Goswami A. D. Hamilton

1991-01-01

101

Characterization of the oligomeric states of insulin in self-assembly and amyloid fibril formation by mass spectrometry.  

PubMed

The self-assembly and aggregation of insulin molecules has been investigated by means of nanoflow electrospray mass spectrometry. Hexamers of insulin containing predominantly two, but up to four, Zn(2+) ions were observed in the gas phase when solutions at pH 4.0 were examined. At pH 3.3, in the absence of Zn(2+), dimers and tetramers are observed. Spectra obtained from solutions of insulin at millimolar concentrations at pH 2.0, conditions under which insulin is known to aggregate in solution, showed signals from a range of higher oligomers. Clusters containing up to 12 molecules could be detected in the gas phase. Hydrogen exchange measurements show that in solution these higher oligomers are in rapid equilibrium with monomeric insulin. At elevated temperatures, under conditions where insulin rapidly forms amyloid fibrils, the concentration of soluble higher oligomers was found to decrease with time yielding insoluble high molecular weight aggregates and then fibrils. The fibrils formed were examined by electron microscopy and the results show that the amorphous aggregates formed initially are converted to twisted, unbranched fibrils containing several protofilaments. Fourier transform infrared spectroscopy shows that both the soluble form of insulin and the initial aggregates are predominantly helical, but that formation of beta-sheet structure occurs simultaneously with the appearance of well-defined fibrils. PMID:10920035

Nettleton, E J; Tito, P; Sunde, M; Bouchard, M; Dobson, C M; Robinson, C V

2000-08-01

102

Solid-State Densification of Spun-Cast Self-Assembled Monolayers for Use in Ultra-Thin Hybrid Dielectrics  

PubMed Central

Ultra-thin self-assembled monolayer (SAM)-oxide hybrid dielectrics have gained significant interest for their application in low-voltage organic thin film transistors (OTFTs). A [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) SAM on ultrathin AlOx (2.5 nm) has been developed to significantly enhance the dielectric performance of inorganic oxides through reduction of leakage current while maintaining similar capacitance to the underlying oxide structure. Rapid processing of this SAM in ambient conditions is achieved by spin coating, however, as-cast monolayer density is not sufficient for dielectric applications. Thermal annealing of a bulk spun-cast PhO-19-PA molecular film is explored as a mechanism for SAM densification. SAM density, or surface coverage, and order are examined as a function of annealing temperature. These SAM characteristics are probed through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). It is found that at temperatures sufficient to melt the as-cast bulk molecular film, SAM densification is achieved; leading to a rapid processing technique for high performance SAM-oxide hybrid dielectric systems utilizing a single wet processing step. To demonstrate low-voltage devices based on this hybrid dielectric (with leakage current density of 7.7×10?8 A cm?2 and capacitance density of 0.62 µF cm?2 at 3 V), pentacene thin-film transistors (OTFTs) are fabricated and yield sub 2 V operation and charge carrier mobilites of up to 1.1 cm2 V?1 s?1.

Hutchins, Daniel O.; Acton, Orb; Weidner, Tobias; Cernetic, Nathan; Baio, Joe E.; Castner, David G.; Ma, Hong; Jen, Alex K.-Y.

2013-01-01

103

Effects of molecular geometry on the self-assembly of giant polymer-dendron conjugates in condensed state.  

PubMed

A series of giant polymer-dendron conjugates with a dendron head and a linear polymer tail were synthesized via"click" chemistry between azide-functionalized polystyrene (PSN, N: degree-of-polymerization) and t-butyl protected, alkyne-functionalized second generation dendron (tD), followed by a deprotection process to generate a dendron termini possessing nine carboxylic acid groups. The molecular structures were confirmed by nuclear magnetic resonance, size-exclusion chromatographic analyses, and matrix-assisted laser desorption ionization time-of-flight mass spectra. These well-defined conjugates can serve as a model system to study the effects of the molecular geometries on the self-assembly behaviour, as compared with their linear analogues. Four phase morphologies found in flexible linear diblock copolymer systems, including lamellae, bicontinuous double gyroids, hexagonal packed cylinders, and body-centred cubic packed spheres, were observed in this series of conjugates based on the results of small angle X-ray scattering and transmission electron microscopy. All of the domain sizes in these phase separated structures were around or less than 10 nm. A 'half' phase diagram was constructed based on the experimental results. The geometrical effect was found not only to enhance the immiscibility between the PSN tail and dendron head, but also systematically shift all of the phase boundaries towards higher volume fractions of the PSN tails, resulting in an asymmetrical phase diagram. This study may provide a pathway to the construction of ordered patterns of sub-10 nm feature size using polymer-dendron conjugates. PMID:24718376

Dong, Xue-Hui; Lu, Xiaocun; Ni, Bo; Chen, Ziran; Yue, Kan; Li, Yiwen; Rong, Lixia; Koga, Tadanori; Hsiao, Benjamin S; Newkome, George R; Shi, An-Chang; Zhang, Wen-Bin; Cheng, Stephen Z D

2014-05-14

104

High-contrast solid-state electrochromic devices of viologen-bridged polysilsesquioxane nanoparticles fabricated by layer-by-layer assembly.  

PubMed

Water-soluble silsesquioxane nanoparticles (NPs) incorporating viologen groups (PXV; 1,1'-bis[3-(trimethoxysilyl)propyl]-4,4'-bipyridinium iodide) have been synthesized by sol-gel polymerization. The electrochromic properties of the bulk film fabricated by layer-by-layer (LbL) assembly have been examined, along with their incorporation into solid-state devices. The orange LbL films show high thermal stability and exhibit a maximum UV-vis absorption at 550 nm. Electrochromic switching of the NPs in liquid electrolyte as well as in the solid state was evaluated by a kinetic study via measurement of the change in transmission (% T) at the maximum contrast. Cyclic voltammograms of the PXV NP LbL films exhibit a reversible reduction at -0.6 V vs Ag/AgCl in a 0.1 M NaClO4(aq) solution, revealing good electrochromic stability, with a color change from orange to dark purple-blue at applied potentials ranging from -0.7 to -1.3 V. Cathodically coloring PXV NP solid-state devices exhibit a switching time of a few seconds between the purple-blue reduced state and the orange oxidized state, showing a contrast of 50% at 550 nm and a coloration efficiency of 205 cm2/C. Their solubility and fairly fast electrochromic switching ( approximately 3 s) at low switching voltages (between 0 and 3.0 V), along with their stability under atmospheric conditions, make PXV NPs good candidates for electrochromic displays. PMID:20355758

Jain, Vaibhav; Khiterer, Mariya; Montazami, Reza; Yochum, Hank M; Shea, Kenneth J; Heflin, James R

2009-01-01

105

Crew Assembly  

NASA Video Gallery

Train to improve your dexterity and hand-eye coordination by assembling a puzzle.The Train Like an Astronaut project uses the excitement of exploration to challenge students to set goals, practice ...

106

Quantum box energies as a route to the ground state levels of self-assembled InAs pyramidal dots  

Microsoft Academic Search

A theoretical investigation of the ground state electronic structure of InAs\\/GaAs quantum confined structures is presented. Energy levels of cuboids and pyramidal shaped dots are calculated using a single-band, constant-confining-potential model that in former applications has proved to reproduce well both the predictions of very sophisticated treatments and several features of many experimental photoluminescence spectra. A connection rule between their

M. Califano; P. Harrison

2000-01-01

107

Conformational transitions in human translin enable nucleic acid binding  

PubMed Central

Translin is a highly conserved RNA- and DNA-binding protein that plays essential roles in eukaryotic cells. Human translin functions as an octamer, but in the octameric crystallographic structure, the residues responsible for nucleic acid binding are not accessible. Moreover, electron microscopy data reveal very different octameric configurations. Consequently, the functional assembly and the mechanism of nucleic acid binding by the protein remain unclear. Here, we present an integrative study combining small-angle X-ray scattering (SAXS), site-directed mutagenesis, biochemical analysis and computational techniques to address these questions. Our data indicate a significant conformational heterogeneity for translin in solution, formed by a lesser-populated compact octameric state resembling the previously solved X-ray structure, and a highly populated open octameric state that had not been previously identified. On the other hand, our SAXS data and computational analyses of translin in complex with the RNA oligonucleotide (GU)12 show that the internal cavity found in the octameric assemblies can accommodate different nucleic acid conformations. According to this model, the nucleic acid binding residues become accessible for binding, which facilitates the entrance of the nucleic acids into the cavity. Our data thus provide a structural basis for the functions that translin performs in RNA metabolism and transport.

Perez-Cano, Laura; Eliahoo, Elad; Lasker, Keren; Wolfson, Haim J.; Glaser, Fabian; Manor, Haim; Bernado, Pau; Fernandez-Recio, Juan

2013-01-01

108

Conformational transitions in human translin enable nucleic acid binding.  

PubMed

Translin is a highly conserved RNA- and DNA-binding protein that plays essential roles in eukaryotic cells. Human translin functions as an octamer, but in the octameric crystallographic structure, the residues responsible for nucleic acid binding are not accessible. Moreover, electron microscopy data reveal very different octameric configurations. Consequently, the functional assembly and the mechanism of nucleic acid binding by the protein remain unclear. Here, we present an integrative study combining small-angle X-ray scattering (SAXS), site-directed mutagenesis, biochemical analysis and computational techniques to address these questions. Our data indicate a significant conformational heterogeneity for translin in solution, formed by a lesser-populated compact octameric state resembling the previously solved X-ray structure, and a highly populated open octameric state that had not been previously identified. On the other hand, our SAXS data and computational analyses of translin in complex with the RNA oligonucleotide (GU)12 show that the internal cavity found in the octameric assemblies can accommodate different nucleic acid conformations. According to this model, the nucleic acid binding residues become accessible for binding, which facilitates the entrance of the nucleic acids into the cavity. Our data thus provide a structural basis for the functions that translin performs in RNA metabolism and transport. PMID:23980029

Pérez-Cano, Laura; Eliahoo, Elad; Lasker, Keren; Wolfson, Haim J; Glaser, Fabian; Manor, Haim; Bernadó, Pau; Fernández-Recio, Juan

2013-11-01

109

Very large assemblies: Optimizing for automatic generation of assembly sequences  

SciTech Connect

Sandia's Archimedes 3.0{copyright} Automated Assembly Analysis System has been applied successfully to several large industrial and weapon assemblies. These have included Sandia assemblies such as portions of the B61 bomb, and assemblies from external customers such as Cummins Engine Inc., Raytheon (formerly Hughes) Missile Systems and Sikorsky Aircraft. While Archimedes 3.0{copyright} represents the state-of-the-art in automated assembly planning software, applications of the software made prior to the technological advancements presented here showed several limitations of the system, and identified the need for extensive modifications to support practical analysis of assemblies with several hundred to a few thousand parts. It was believed that there was substantial potential for enhancing Archimedes 3.0{copyright} to routinely handle much larger models and/or to handle more modestly sized assemblies more efficiently. Such a mature assembly analysis capability was needed to support routine application to industrial assemblies that overstressed the system, such as full nuclear weapon assemblies or full-scale aerospace or military vehicles.

CALTON,TERRI L.

2000-02-01

110

Neutronics, steady-state, and transient analyses for the Poland MARIA reactor for irradiation testing of LEU lead test fuel assemblies from CERCA : ANL independent verification results.  

SciTech Connect

The MARIA reactor at the Institute of Atomic Energy (IAE) in Swierk (30 km SE of Warsaw) in the Republic of Poland is considering conversion from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel assemblies (FA). The FA design in MARIA is rather unique; a suitable LEU FA has never been designed or tested. IAE has contracted with CERCA (the fuel supply portion of AREVA in France) to supply 2 lead test assemblies (LTA). The LTAs will be irradiated in MARIA to burnup level of at least 40% for both LTAs and to 60% for one LTA. IAE may decide to purchase additional LEU FAs for a full core conversion after the test irradiation. The Reactor Safety Committee within IAE and the National Atomic Energy Agency in Poland (PAA) must approve the LTA irradiation process. The approval will be based, in part, on IAE submitting revisions to portions of the Safety Analysis Report (SAR) which are affected by the insertion of the LTAs. (A similar process will be required for the full core conversion to LEU fuel.) The analysis required was established during working meetings between Argonne National Laboratory (ANL) and IAE staff during August 2006, subsequent email correspondence, and subsequent staff visits. The analysis needs to consider the current high-enriched uranium (HEU) core and 4 core configurations containing 1 and 2 LEU LTAs in various core positions. Calculations have been performed at ANL in support of the LTA irradiation. These calculations are summarized in this report and include criticality, burn-up, neutronics parameters, steady-state thermal hydraulics, and postulated transients. These calculations have been performed at the request of the IAE staff, who are performing similar calculations to be used in their SAR amendment submittal to the PAA. The ANL analysis has been performed independently from that being performed by IAE and should only be used as one step in the verification process.

Garner, P. L.; Hanan, N. A. (Nuclear Engineering Division)

2011-06-07

111

Octameric Stoichiometry of the KATP Channel Complex  

Microsoft Academic Search

ATP-sensitive potassium (K ATP ) channels link cellular metabolism to electrical activity in nerve, mus- cle, and endocrine tissues. They are formed as a functional complex of two unrelated subunits—a member of the Kir inward rectifier potassium channel family, and a sulfonylurea receptor (SUR), a member of the ATP-binding cassette transporter family, which includes cystic fibrosis transmembrane conductance regulators and

S.-L. Shyng; C. G. Nichols

1997-01-01

112

Self-assembly of liquid crystal block copolymer PEG-b-smectic polymer in pure state and in dilute aqueous solution.  

PubMed

A series of amphiphilic LC block copolymers, in which the hydrophobic block is a smectic polymer poly(4-methoxyphenyl 4-(6-acryloyloxy-hexyloxy)-benzoate) (PA6esterl) and the hydrophilic block is polyethyleneglycol (PEG), were synthesized and characterized. The self-assembly of one of them in both the pure state and the dilute aqueous solution was investigated in detail. Nano-structures in the pure state were studied by SAXS and WAXS on samples aligned by a magnetic field. A hexagonal cylindrical micro-segregation phase was observed with a lattice distance of 11.2 nm. The PEG blocks are in the cylinder, while the smectic polymer blocks form a matrix with layer spacing 2.4 nm and layer normal parallel to the long axis of the cylinders. Faceted unilamellar polymer vesicles, polymersomes, were formed in water, as revealed by cryo-TEM. In the lyotropic bilayer membrane of these polymersomes, the thermotropic smectic order in the hydrophobic block is clearly visible with layer normal parallel to the membrane surface. PMID:20334105

Xu, Bing; Piñol, Rafael; Nono-Djamen, Merveille; Pensec, Sandrine; Keller, Patrick; Albouy, Pierre-Antoine; Lévy, Daniel; Li, Min-Hui

2009-01-01

113

Single-Molecule Spectroscopy Unmasks the Lowest Exciton State of the B850 Assembly in LH2 from Rps. acidophila.  

PubMed

We have recorded fluorescence-excitation and emission spectra from single LH2 complexes from Rhodopseudomonas (Rps.) acidophila. Both types of spectra show strong temporal spectral fluctuations that can be visualized as spectral diffusion plots. Comparison of the excitation and emission spectra reveals that for most of the complexes the lowest exciton transition is not observable in the excitation spectra due to the cutoff of the detection filter characteristics. However, from the spectral diffusion plots we have the full spectral and temporal information at hand and can select those complexes for which the excitation spectra are complete. Correlating the red most spectral feature of the excitation spectrum with the blue most spectral feature of the emission spectrum allows an unambiguous assignment of the lowest exciton state. Hence, application of fluorescence-excitation and emission spectroscopy on the same individual LH2 complex allows us to decipher spectral subtleties that are usually hidden in traditional ensemble spectroscopy. PMID:24806933

Kunz, Ralf; Timpmann, Kõu; Southall, June; Cogdell, Richard J; Freiberg, Arvi; Köhler, Jürgen

2014-05-01

114

Human recombinant mutated forms of the mitochondrial COX assembly Sco2 protein differ from wild-type in physical state and copper binding capacity.  

PubMed

The human Sco2 protein is a cytochrome c oxidase assembly protein that participates in mitochondrial copper pathway, acting downstream of Cox17 protein. In a previous work, we detected mutations in the human SCO2 gene in three unrelated infants with fatal cardioencephalomyopathy and COX deficiency. In this study, full-length processed recombinant wild-type and two mutated forms of hSco2p (w/t-rhSco2p, E140K-rhSco2p, and S225F-rhSco2p) were produced in bacteria as soluble recombinant peptides for the first time and evaluated for differences in their physical state and ability to bind copper. Our data indicate the following: (a) w/t-rhSco2p and S225F-rhSco2p were found to be in a monomeric form in contrast to E140K-rhSco2p that was in a major non-reducible dimer and a minor monomer form; (b) wild-type and mutated rhSco2p exhibited clear differences in their physical conformational state, as shown by circular dichroism and thermal denaturation analyses; (c) copper binding studies showed that E140K-rhSco2p bound markedly less copper while S225F-rhSco2p more than expected as compared to amount of the copper bound with w/t-rhSco2p. rhCox17p served as positive control experiment. These data indicate that S225F and E140K mutations found in the SCO2 gene derived from patients alter the physical conformational state of encoded hSco2p that may disturb the normal copper transport pathway in mitochondria. These findings are valuable for understanding the molecular basis of fatal cardioencephalomyopathy and COX deficiency and for designing appropriate pharmacological interventions. PMID:14972329

Foltopoulou, Parthena F; Zachariadis, George A; Politou, Anastasia S; Tsiftsoglou, Asterios S; Papadopoulou, Lefkothea C

2004-03-01

115

Generation of precedence relations for mechanical assemblies  

NASA Technical Reports Server (NTRS)

Planning of assembly sequences is essential to the manufacturing system design process. Several methodologies have been proposed to represent all the feasible assembly sequences. In this thesis, three algorithms are presented to generate three sets of precedence relations based on all the infeasible assembly tasks, all the infeasible assembly states, and all the feasible assembly sequences, respectively. The equivalence of the resulting sets of precedence relations to the AND/OR graph is established. A new property, the real time property, of a representation of assembly sequences is defined and discussed. A representation of assembly sequences is said to have the real time property, if it is possible to generate the next assembly task by testing locally in the representation, and it will guarantee that the generated assembly task will not lead the assembly sequence to a dead end situation, in which no feasible assembly task can be performed any more. It is shown that the correctness and completeness of one representation can not guarantee the real time property of the representation. It is proven that the directed graph representation and the set of precedence relations based on all the infeasible assembly states have the real time property, while the AND/OR graph representation and the set of precedence relations based on all the infeasible assembly tasks do not have the real time property. Finally in the thesis, the PLEIDEAS system, a PLanning Environment for Integrated DEsign of Assembly Systems, is described and illustrated by an example.

Zhang, Hui; Sanderson, A. C.

1989-01-01

116

Anion-controlled assembly of silver-di(aminophenyl)sulfone coordination polymers: Syntheses, crystal structures, and solid state luminescence  

NASA Astrophysics Data System (ADS)

Five silver coordination polymers, namely, {[Ag(3,3?-daps)2]·BF4}n (1), {[Ag(3,3?-daps)2]·NO3}n (2), [Ag(3,3?-daps)(CF3SO3)]n (3), {[Ag(4,4?-daps)]·CF3SO3}n (4), and {[Ag(4,4?-daps)]·ClO4}n (5) (3,3?-daps=di(3?-aminodiphenyl)sulfone, and 4,4?-daps=di(4?-aminodiphenyl)sulfone) have been synthesized and structural characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction analyses. Complex 1 displays a 1D ladder-like chain with four-connected Ag ions and bridged 3,3?-daps. Complex 2 shows other 1D ladder chain modified by tentacles. Complex 3 is a 2D layer structure with both Ag ions and 3,3?-daps are 3-connected nodes. Complex 4 is another 1D ladder chain with three-connected Ag ions and 4,4?-daps. Complex 5 shows a 2D 44-sql net with Ag ions and 4,4?-daps as 4-connected nodes. Moreover, their solid state luminescence and thermal stabilities also have been investigated.

Zhang, Qi-Long; Hu, Peng; Zhao, Yi; Feng, Guang-Wei; Zhang, Yun-Qian; Zhu, Bi-Xue; Tao, Zhu

2014-02-01

117

Latch assembly  

DOEpatents

A latch assembly for releasably securing an article in the form of a canister within a container housing. The assembly includes a cam pivotally mounted on the housing wall and biased into the housing interior. The cam is urged into a disabled position by the canister as it enters the housing and a latch release plate maintains the cam disabled when the canister is properly seated in the housing. Upon displacement of the release plate, the cam snaps into latching engagement against the canister for securing the same within the housing.

Frederickson, James R. (Richland, WA) [Richland, WA; Harper, William H. (Richland, WA) [Richland, WA; Perez, Raymond (Lynnwood, WA) [Lynnwood, WA

1986-01-01

118

Local and translational dynamics in DNA-lipid assemblies monitored by solid-state and diffusion NMR.  

PubMed

The influence of electrostatic interactions on the dynamic properties of complexes containing DNA and mixtures of cationic- (DDA) and zwitterionic (DLPC) lipids are studied by means of NMR. The systems are arranged in lamellar membrane stacks intercalated by DNA molecules. This is confirmed by 31P-NMR, where a superposition of an axially symmetric powder pattern arising from the phospholipid membrane and an asymmetric tensor due to DNA can be fitted to the experimentally observed lineshape. The local mobility and order is assessed using two solid-state NMR techniques applicable to samples with natural isotopic abundance: WIdeline SEparation (WISE) and Separated Local Field (SLF) spectroscopy. Both experiments yield highly resolved 13C spectra in the direct dimension. The indirect dimension contains information about molecular dynamics through the 1H dipolar linewidth (WISE) or the 1H(-13)C dipolar coupling constant (SLF). The experiments suggest that DNA is static while it induces an increased disorder in the hydrocarbon chains as compared to the parent lipid case. DDA chain order is more affected than DLPC due to the attractive electrostatic interaction between DNA and the cationic lipid. Translational dynamics of the lipids and the water was measured with the Pulsed Field Gradient STimulated Echo (PFG STE) technique. The influence of lamellar domain size and the angular dependence of the diffusion coefficients and nuclear relaxation times on the results of the PFG STE experiments are discussed. The local water diffusion coefficient is reduced by a factor four from the value of bulk water, and increases as the DLPC content is increased. We observe two lipid components with an order of magnitude difference in diffusion coefficients in the DNA:DDA:DLPC precipitate and these are assigned to DLPC (fast) and DDA (slow). Cationic lipid (DDA) diffusion is decreasing a factor of 2 when DLPC is added to the pure DNA:DDA system, indicating DNA-induced lipid segregation within the bilayer and the transition from locally 2D to 1D diffusion of the DDA. The results show that DNA-lipid electrostatic interactions reduce the long-range lipid mobility but locally enhance the hydrocarbon chain dynamics by perturbing the preferred lipid packing. PMID:18320639

Leal, Cecília; Sandström, Dick; Nevsten, Pernilla; Topgaard, Daniel

2008-01-01

119

Assembling GRETINA  

ScienceCinema

GRETINA is the most sensitive gamma-ray detector ever built for studies of the nucleus, including how the natural elements were made in stars and supernovae, and the properties of artificial superheavy elements. GRETINA, now being assembled at Berkeley Lab's 88-Inch Cyclotron, is the first stage of GRETA, the even more powerful Gamma-Ray Energy Tracking Array.

120

Latch assembly  

Microsoft Academic Search

A latch assembly is described for releasably securing an article in an apparatus housing having a side wall and a bottom wall comprising: a latching cam mounted on the housing wall for pivoted movement between an operative position and an inoperative position wherein the cam is triangular in side elevation and formed with a first portion of solid thickness and

J. R. Fredrickson; W. H. Harper; R. Perez

1986-01-01

121

Furnace assembly  

DOEpatents

A method of and apparatus for heating test specimens to desired elevated temperatures for irradiation by a high energy neutron source. A furnace assembly is provided for heating two separate groups of specimens to substantially different, elevated, isothermal temperatures in a high vacuum environment while positioning the two specimen groups symmetrically at equivalent neutron irradiating positions.

Panayotou, Nicholas F. (Kennewick, WA); Green, Donald R. (Richland, WA); Price, Larry S. (Pittsburg, CA)

1985-01-01

122

Assembling GRETINA  

SciTech Connect

GRETINA is the most sensitive gamma-ray detector ever built for studies of the nucleus, including how the natural elements were made in stars and supernovae, and the properties of artificial superheavy elements. GRETINA, now being assembled at Berkeley Lab's 88-Inch Cyclotron, is the first stage of GRETA, the even more powerful Gamma-Ray Energy Tracking Array.

Lee, I-Yang

2010-01-01

123

Battery assembly  

SciTech Connect

The disclosure describes a battery assembly which comprises several gas depolarizable electrochemical cells, e.g., metal/air cells, stacked electrically in series along a first dimension. Each cell has first and second electrodes of opposite polarities. The battery assembly also comprises a housing for containing the stack of cells. The housing includes a structure for ventilating the interior of the housing and further includes first and second opposite end walls which lie perpendicular to the first dimension. The stack of cells is arranged within the housing with the first electrode of the initial cell of the stack facing the first wall and the second electrode of the final cell of the stack facing the second wall. The battery assembly further includes first and second electrically conductive connectors disposed within the housing. The first connector has a first end electrically coupled to the first electrode of the initial cell and a second end disposed adjacent the first wall. The second connector has a first end electrically coupled to the second electrode of the final cell and a second end also disposed adjacent the first wall. The battery assembly further comprises first and second terminals which are electrically coupled to the first and second connectors, respectively, and extend through the first wall to the exterior of the housing.

McArthur, W.J.; Kelm, R.W.

1985-10-15

124

Heptanuclear antiferromagnetic Fe(III)-D-(-)-quinato assemblies with an S = 3/2 ground state-pH-specific synthetic chemistry, spectroscopic, structural, and magnetic susceptibility studies.  

PubMed

Iron is an essential metal ion with numerous roles in biological systems and advanced abiotic materials. D-(-)-quinic acid is a cellular metal ion chelator, capable of promoting reactions with metal M(II,III) ions under pH-specific conditions. In an effort to comprehend the chemical reactivity of well-defined forms of Fe(III)/Fe(II) toward ?-hydroxycarboxylic acids, pH-specific reactions of: (a) [Fe3O(CH3COO)6(H2O)3]·(NO3)·4H2O with D-(-)-quinic acid in a molar ratio 1:3 at pH 2.5 and (b) Mohr's salt with D-(-)-quinic acid in a molar ratio 1:3 at pH 7.5, respectively, led to the isolation of the first two heptanuclear Fe(III)-quinato complexes, [Fe7O3(OH)3(C7H10O6)6]·20.5H2O (1) and (NH4)[Fe7(OH)6(C7H10O6)6]·(SO4)2·18H2O (2). Compounds 1 and 2 were characterized by analytical, spectroscopic (UV-vis, FT-IR, EPR, and Mössbauer) techniques, CV, TGA-DTG, and magnetic susceptibility measurements. The X-ray structures of 1 and 2 reveal heptanuclear assemblies of six Fe(III) ions bound by six doubly deprotonated quinates and one Fe(III) ion bound by oxido- and hydroxido-bridges (1), and hydroxido-bridges (2), all in an octahedral fashion. Mössbauer spectroscopy on 1 and 2 suggests the presence of Fe(III) ions in an all-oxygen environment. EPR measurements indicate that 1 and 2 retain their structure in solution, while magnetic measurements reveal an overall antiferromagnetic behavior with a ground state S = 3/2. The collective physicochemical properties of 1 and 2 suggest that the (a) nature of the ligand, (b) precursor form of iron, (c) pH, and (d) molecular stoichiometry are key factors influencing the chemical reactivity of the binary Fe(II,III)-hydroxycarboxylato systems, their aqueous speciation, and ultimately through variably emerging hydrogen bonding interactions, the assembly of multinuclear Fe(III)-hydroxycarboxylato clusters with distinct lattice architectures of specific dimensionality (2D-3D) and magnetic signature. PMID:24266671

Menelaou, M; Vournari, E; Psycharis, V; Raptopoulou, C P; Terzis, A; Tangoulis, V; Sanakis, Y; Mateescu, C; Salifoglou, A

2013-12-16

125

Nitrogenase assembly.  

PubMed

Nitrogenase contains two unique metalloclusters: the P-cluster and the M-cluster. The assembly processes of P- and M-clusters are arguably the most complicated processes in bioinorganic chemistry. There is considerable interest in decoding the biosynthetic mechanisms of the P- and M-clusters, because these clusters are not only biologically important, but also chemically unprecedented. Understanding the assembly mechanisms of these unique metalloclusters is crucial for understanding the structure-function relationship of nitrogenase. Here, we review the recent advances in this research area, with an emphasis on our work that provide important insights into the biosynthetic pathways of these high-nuclearity metal centers. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. PMID:23232096

Hu, Yilin; Ribbe, Markus W

2013-01-01

126

Planning Assembly Of Large Truss Structures In Outer Space  

NASA Technical Reports Server (NTRS)

Report dicusses developmental algorithm used in systematic planning of sequences of operations in which large truss structures assembled in outer space. Assembly sequence represented by directed graph called "assembly graph", in which each arc represents joining of two parts or subassemblies. Algorithm generates assembly graph, working backward from state of complete assembly to initial state, in which all parts disassembled. Working backward more efficient than working forward because it avoids intermediate dead ends.

De Mello, Luiz S. Homem; Desai, Rajiv S.

1992-01-01

127

Container assembly  

US Patent & Trademark Office Database

The container assembly is adapted for high speed packaging of perishable items. The container is formed with ribbed walls to add rigidity to the structure. The reinforcing ribs are perforated to allow air to circulate through the packaged goods. The ribs are shaped to maintain the perforations open during stacking and shipping. The mouth of the container has a peripheral flange. The flange has integral hinged closures for securing a separate top.

2003-12-23

128

Seal assembly  

DOEpatents

A seal assembly comprises a tube rotatable about its longitudinal axis and having two longitudinally spaced flanges projecting radially outwardly from the outer surface thereof. Slidably positioned against one of the flanges is a seal ring, and disposed between this seal ring and the other flange are two rings that are forced apart by springs, one of the latter rings being attached to a flexible wall.

Morgan, J.G.; Rennich, M.J.; Whatley, M.E.

1981-03-13

129

Dump assembly  

DOEpatents

A dump assembly having a fixed conduit and a rotatable conduit provided with overlapping plates, respectively, at their adjacent ends. The plates are formed with openings, respectively, normally offset from each other to block flow. The other end of the rotatable conduit is provided with means for securing the open end of a filled container thereto. Rotation of the rotatable conduit raises and inverts the container to empty the contents while concurrently aligning the conduit openings to permit flow of material therethrough.

Goldmann, Louis H. (Benton City, WA) [Benton City, WA

1986-01-01

130

Self-assembling formation of Si-based quantum dots and control of their electric charged states for multi-valued memories  

NASA Astrophysics Data System (ADS)

We have prepared hemispherical Si nanocrystals as quantum dots (QDs) on thermally-grown SiO II layers in a self-assembled manner by controlling the early stages of LPCVD using SiH 4, and also formed Si-QDs with a Ge core by controlling the selective growth conditions in SiH 4- and GeH 4-LPCVD. From the change in the surface potential at each of QDs caused by electron injection or emission through ultrathin SiO II as measured with an AMF/Kelvin probe technique, we have quantified how many electrons or holes can be retained stably in the single dot covered with ultrathin SiO II at room temperature without any external biases. We have found that, for Si-QDs with a Ge core, electrons are retained stably in Si clad while holes in Ge core. MOS capacitors and FETs with the Si dots as a floating gate have also been designed and fabricated. Multiple-step electron charging (or discharging) characteristics of the Si-dot floating gate are observable presumably because columbic force arising from charged dots efficiently suppresses the electron charging of neighboring neutral dots. From the temperature dependence of temporal change in the drain current at a fixed positive gate bias after complete discharging of the Si-QDs floating gate, we were found that the multiple step charging proceeds with an thermal activation energy being almost equal to the energy separation in the sum of quantized and charging energies between the charged states.

Miyazaki, Seiichi

2005-11-01

131

Neutral acyclic anion receptor with thiadiazole spacer: halide binding study and halide-directed self-assembly in the solid state.  

PubMed

A halide binding study of a newly synthesized neutral acyclic receptor LH(2) with a thiadiazole spacer has been methodically performed both in solution and in the solid state. Crystal structure analysis of the halide complexes elucidate the fact that fluoride forms an unusual 1:1 hyrogen-bonded complex with monodeprotonated receptor, whereas in the case of other congeners, such as chloride and bromide, the receptor binds two halide anions along with formation of a halide-bridged 1D polymeric chain network by participation of N-H···X(-) and aromatic C-H···X(-) hydrogen-bonding (where X = Cl and Br) interactions. The presence of a rigid thiadiazole spacer presumably opens up enough space for capturing two halide anions by a single receptor molecule, where the coordinated -NH protons are pointed in the same direction with respect to the spacer and eventually favor formation of halide (Cl(-) and Br(-)) induced polymeric architecture, although no obvious chloride- or bromide-directed polymeric assembly is found in solution. A significant red shift of 243 nm in the absorption spectra of LH(2) was solely observed in the presence of excess fluoride anion, which enables LH(2) as an efficient colorimetric sensor for optical detection of fluoride anion (yellow to blue). Furthermore, spectroscopic titration experiments with increasing equivalents of fluoride anion suggest formation of a H-bonded complex with subsequent stepwise deprotonation of two N-H groups, which can be visually monitored by a change in color from yellow to blue via pink. PMID:22221211

Basu, Arghya; Das, Gopal

2012-01-16

132

TIGER: tiled iterative genome assembler  

PubMed Central

Background With the cost reduction of the next-generation sequencing (NGS) technologies, genomics has provided us with an unprecedented opportunity to understand fundamental questions in biology and elucidate human diseases. De novo genome assembly is one of the most important steps to reconstruct the sequenced genome. However, most de novo assemblers require enormous amount of computational resource, which is not accessible for most research groups and medical personnel. Results We have developed a novel de novo assembly framework, called Tiger, which adapts to available computing resources by iteratively decomposing the assembly problem into sub-problems. Our method is also flexible to embed different assemblers for various types of target genomes. Using the sequence data from a human chromosome, our results show that Tiger can achieve much better NG50s, better genome coverage, and slightly higher errors, as compared to Velvet and SOAPdenovo, using modest amount of memory that are available in commodity computers today. Conclusions Most state-of-the-art assemblers that can achieve relatively high assembly quality need excessive amount of computing resource (in particular, memory) that is not available to most researchers to achieve high quality results. Tiger provides the only known viable path to utilize NGS de novo assemblers that require more memory than that is present in available computers. Evaluation results demonstrate the feasibility of getting better quality results with low memory footprint and the scalability of using distributed commodity computers.

2012-01-01

133

Resorcinol-templated head-to-head photodimerization of a thiophene in the solid state and unusual edge-to-face stacking in a discrete hydrogen-bonded assembly.  

PubMed

A head-to-head photodimerization of a ?-substituted thiophene stacked face-to-face in the solid state using a ditopic hydrogen-bond-donor template is reported. The face-to-face stacking is attributed to contributions of intertemplate forces, which contrasts an assembly wherein the same thiophenes stack edge-to-face yet maintain a discrete hydrogen-bonded structure. PMID:24499324

Hutchins, Kristin M; Sumrak, Joseph C; MacGillivray, Leonard R

2014-02-21

134

Los Alamos Critical Assemblies Facility  

SciTech Connect

The Critical Assemblies Facility of the Los Alamos National Laboratory has been in existence for thirty-five years. In that period, many thousands of measurements have been made on assemblies of /sup 235/U, /sup 233/U, and /sup 239/Pu in various configurations, including the nitrate, sulfate, fluoride, carbide, and oxide chemical compositions and the solid, liquid, and gaseous states. The present complex of eleven operating machines is described, and typical applications are presented.

Malenfant, R.E.

1981-06-01

135

Dump assembly  

DOEpatents

This is a claim for a dump assembly having a fixed conduit and a rotatable conduit provided with overlapping plates, respectively, at their adjacent ends. The plates are formed with openings, respectively, normally offset from each other to block flow. The other end of the rotatable conduit is provided with means for securing the open end of a filled container thereto. Rotation of the rotatable conduit raises and inverts the container to empty the contents while concurrently aligning the conduit openings to permit flow of material therethrough. 4 figs.

Goldmann, L.H.

1984-12-06

136

Micromanifold assembly  

DOEpatents

A micromanifold for connecting external capillaries to the inlet and/or outlet ports of a microfluidic device can employ a ferrule/capillary assembly that includes: (a) a ferrule comprising an elongated member and having a bore traversing from a proximal end to a distal end of the member, wherein the bore has an inner surface and wherein the distal end of the ferrule has a tapered, threaded exterior surface, and (b) a capillary that is positioned within the bore wherein the capillary's outer surface is in direct contact with the bore's inner surface. No mating sleeve is required for the one-piece ferrule. Alternatively, the capillaries can be bonded to channels that traverse the manifold and therefore obviate the need for a ferrule.

Renzi, Ronald F. (Tracy, CA); Ferko, Scott M. (Livermore, CA)

2012-04-24

137

Micromanifold assembly  

DOEpatents

A micromanifold for connecting external capillaries to the inlet and/or outlet ports of a microfluidic device can employ a ferrule/capillary assembly that includes: (a) a ferrule comprising an elongated member and having a bore traversing from a proximal end to a distal end of the member, wherein the bore has an inner surface and wherein the distal end of the ferrule has a tapered, threaded exterior surface, and (b) a capillary that is positioned within the bore wherein the capillary's outer surface is in direct contact with the bore's inner surface. No mating sleeve is required for the one-piece ferrule. Alternatively, the capillaries can be bonded to channels that traverse the manifold and therefore obviate the need for a ferrule.

Renzi, Ronald F. (Tracey, CA); Ferko, Scott (Livermore, CA)

2009-06-30

138

Thermocouple assembly  

DOEpatents

A thermocouple assembly includes a thermocouple; a plurality of lead wires extending from the thermocouple; an insulating jacket extending along and enclosing the plurality of leads; and at least one internally sealed area within the insulating jacket to prevent fluid leakage along and within the insulating jacket. The invention also provides a method of preventing leakage of a fluid along and through an insulating jacket of a thermocouple including the steps of a) attaching a plurality of lead wires to a thermocouple; b) adding a heat sensitive pseudo-wire to extend along the plurality of lead wires; c) enclosing the lead wires and pseudo-wire inside an insulating jacket; d) locally heating axially spaced portions of the insulating jacket to a temperature which melts the pseudo-wire and fuses it with an interior surface of the jacket.

Thermos, Anthony Constantine (Greer, SC); Rahal, Fadi Elias (Easley, SC)

2002-01-01

139

Transmission assembly  

SciTech Connect

This paper discusses a transmission assembly. It comprises a first automatic transmission having a forward end adapted to be coupled to an internal combustion engine and a rearward end, the first automatic transmission including a drive shaft; a second automatic transmission having a forward end and a rearward end, and including a stator plate having a forward portion and a rearward portion. The stator plate located adjacent the forward end of the second automatic transmission, the drive shaft connecting the first automatic transmission in driving relation with the second automatic transmission; a coupling plate for connecting the rearward end of the first automatic transmission with the forward end of the second automatic transmission. The coupling plate rotatably supporting the drive shaft; and means for providing communication of pressurized transmission fluid between the first and second automatic transmissions.

Klazura, K.

1990-08-28

140

Automated Assembly Center (AAC).  

National Technical Information Service (NTIS)

The objectives of this project are as follows: to integrate advanced assembly and assembly support technology under a comprehensive architecture; to implement automated assembly technologies in the production of high-visibility DOD weapon systems; and to ...

R. J. Stauffer

1993-01-01

141

Special Test Equipment and Fixturing for MSAT Reflector Assembly Alignment.  

National Technical Information Service (NTIS)

The MSAT Reflector Assembly is a state of the art subsystem for Mobile Satellite (MSAT), a geosynchronous-based commercial mobile telecommunication satellite program serving North America. The Reflector Assembly consisted of a deployable, three-hinge, fol...

J. A. Young M. R. Zinn D. R. Mccarten

1994-01-01

142

Solar heat collector assembly  

SciTech Connect

A solar heat collector assembly includes a cylindrical transparent tube having an open end portion hermetically sealed by the use of a sealant and being held in vacuum state and a heat-collecting pipe secured in the transparent tube with its end portion extending outside the transparent tube through the sealant. The sealant is made of a thermally-nonconducting and anti-corrosion material with a softening point higher than that of the transparent tube. Especially, the sealant is made of ceramics or crystallized glass.

Shimada, M.; Katto, A.

1983-10-18

143

Modeling and design of a new core-moderator assembly and neutron beam ports for the Penn State Breazeale Nuclear Reactor (PSBR)  

NASA Astrophysics Data System (ADS)

This study is for modeling and designing a new reactor core-moderator assembly and new neutron beam ports that aimed to expand utilization of a new beam hall of the Penn State Breazeale Reactor (PSBR). The PSBR is a part of the Radiation Science and Engineering Facility (RSEC) and is a TRIGA MARK III type research reactor with a movable core placed in a large pool and is capable to produce 1MW output. This reactor is a pool-type reactor with pulsing capability up to 2000 MW for 10-20 msec. There are seven beam ports currently installed to the reactor. The PSBR's existing core design limits the experimental capability of the facility, as only two of the seven available neutron beam ports are usable. The finalized design features an optimized result in light of the data obtained from neutronic and thermal-hydraulics analyses as well as geometrical constraints. A new core-moderator assembly was introduced to overcome the limitations of the existing PSBR design, specifically maximizing number of available neutron beam ports and mitigating the hydrogen gamma contamination of the neutron beam channeled in the beam ports. A crescent-shaped moderator is favored in the new PSBR design since it enables simultaneous use of five new neutron beam ports in the facility. Furthermore, the crescent shape sanctions a coupling of the core and moderator, which reduces the hydrogen gamma contamination significantly in the new beam ports. A coupled MURE and MCNP5 code optimization analysis was performed to calculate the optimum design parameters for the new PSBR. Thermal-hydraulics analysis of the new design was achieved using ANSYS Fluent CFD code. In the current form, the PSBR is cooled by natural convection of the pool water. The driving force for the natural circulation of the fluid is the heat generation within the fuel rods. The convective heat data was generated at the reactor's different operating powers by using TRIGSIMS, the fuel management code of the PSBR core. In the CFD modeling, the amount of heat generated by the fuel is assumed to be transferred totally into the coolant. Therefore, the surface heat flux is applied to the fuel cladding outer surface by considering the depleted fuel composition of each individual fuel rod under a reference core loading condition defined as; 53H at 1MW full power. In order to model the entire PSBR reactor, fine mesh discretization was achieved with 22 millions structured and unstructured computational meshes. The conductive heat transfer inside the fuel rods was ignored in order to decrease the computational mesh requirement. Since the PSBR core operates in the subcooled nucleate boiling region, the CFD simulation of new PSBR design was completed utilizing an Eulerian-Eulerian multiphase flow formulation and RPI wall boiling model. The simulation results showed that the new moderator tank geometry results in secondary flow entering into the core due to decrease in the cross-flow area. Notably, the radial flow improves the local heat transfer conditions by providing radial-mixing in the core. Bubble nucleation occurs on the heated fuel rods but bubbles are collapsing in the subcooled fluid. Furthermore, the bulk fluid properties are not affected by the bubble formation. Yet, subcooled boiling enhances the heat transfer on the fuel rods. Five neutron beam ports are designed for the new reactor. The geometrical configuration, filter and collimator system designs of each neutron beam ports are selected based on the requirements of the experimental facilities. A cold neutron beam port which utilizes cold neutrons from three curved guide tubes is considered. Therefore, there will be seven neutron beams available in the new facility. The neutronic analyses of the new beam port designs were achieved by using MCNP5 code and Burned Coupled Simulation Tool for the PSBR. The MCNP simulation results showed that thermal neutron flux was increased by a factor of minimum 1.23 times and maximum 2.68 times in the new beam port compared to the existing BP4 design. Besides total gamma dose was decreased by a factor

Ucar, Dundar

144

Self-assembly behavior of tail-to-tail superstructure formed by mono-6-O-(4-carbamoylmethoxy-benzoyl)-?-cyclodextrin in solution and the solid state.  

PubMed

A novel mono-modified ?-cyclodextrin (?-CD) consisting of 4-carbamoylmethoxy-benzoyl unit at the primary side was synthesized and its self-assembly behavior was determined by X-ray crystallography and NMR spectroscopy. The crystal structure shows a 'Yin-Yang'-like packing mode, in which the modified ?-CD exhibits a channel superstructure formed by a tail-to-tail dimer as the repeating motif with the substituted group embedded within the hydrophobic cavity of the facing ?-CD. The geometry of the substituted group is determined by the inclusion of the cavity and is further stabilized by two intermolecular hydrogen bonds between the carbonyl O atom and phenyl group. Furthermore, NMR ROESY investigation indicates that the self-assembly behavior of the substituted group within the ?-CD cavity is retained in aqueous solution, and the effective binding constant Ka was calculated to be 1330M(-1) by means of (1)H NMR titration according to iterative determination. PMID:24887704

Xu, Zhe; Chen, Xin; Liu, Jing; Yan, Dong-Qing; Diao, Chun-Hua; Guo, Min-Jie; Fan, Zhi

2014-07-01

145

Layer-by-layer assembly of poly(aniline- N-butylsulfonate)s and their electrochromic properties in an all solid state window  

Microsoft Academic Search

Layer-by-layer (LBL) self-assembly by sequential adsorption of a polyanion, poly(aniline-N-butylsulfonate)s (PANBUS), onto oppositely charged cation, vinylbenzyldimethyldodecylammonium chloride (VDAC), led to the formation of ultra thin films at indium–tin oxide (ITO) glasses. The building up of such multilayer films was characterized by the increment of the absorbance through UV–visible spectroscopy, which indicated a linear dependence of the absorbance on the number

Soonkyo Jung; Hoonjung Kim; Mijeong Han; Yongku Kang; Eunkyoung Kim

2004-01-01

146

Formation and optical properties of CdTe self-assembled pyramids with quantum states grown on ZnTe buffer layers  

Microsoft Academic Search

Atomic force microscopy (AFM) and photoluminescence (PL) measurements were carried out to investigate the structure and to determine the electron activation energy in CdTe\\/ZnTe pyramids grown by using molecular beam epitaxy and atomic layer epitaxy methods. The AFM images showed that self-assembled CdTe pyramids were formed on ZnTe buffer layers. The PL spectra showed that the formed CdTe pyramids had

E. H. Lee; K. H. Lee; J. S. Kim; H. L. Park; T. W. Kim

2003-01-01

147

Yeast prions assembly and propagation  

PubMed Central

Yeast prions are self-perpetuating protein aggregates that are at the origin of heritable and transmissible non-Mendelian phenotypic traits. Among these, [PSI+], [URE3] and [PIN+] are the most well documented prions and arise from the assembly of Sup35p, Ure2p and Rnq1p, respectively, into insoluble fibrillar assemblies. Fibril assembly depends on the presence of N- or C-terminal prion domains (PrDs) which are not homologous in sequence but share unusual amino-acid compositions, such as enrichment in polar residues (glutamines and asparagines) or the presence of oligopeptide repeats. Purified PrDs form amyloid fibrils that can convert prion-free cells to the prion state upon transformation. Nonetheless, isolated PrDs and full-length prion proteins have different aggregation, structural and infectious properties. In addition, mutations in the “non-prion” domains (non-PrDs) of Sup35p, Ure2p and Rnq1p were shown to affect their prion properties in vitro and in vivo. Despite these evidences, the implication of the functional non-PrDs in fibril assembly and prion propagation has been mostly overlooked. In this review, we discuss the contribution of non-PrDs to prion assemblies, and the structure-function relationship in prion infectivity in the light of recent findings on Sup35p and Ure2p assembly into infectious fibrils from our laboratory and others.

2011-01-01

148

Radiation Chemistry in Organized Assemblies.  

ERIC Educational Resources Information Center

Expands the basic concepts regarding the radiation chemistry of simple aqueous systems to more complex, but well defined, organized assemblies. Discusses the differences in behavior in comparison to simple systems. Reviews these techniques: pulse radiolysis, laser flash, photolysis, and steady state irradiation by gamma rays or light. (CS)

Thomas, J. K.; Chen, T. S.

1981-01-01

149

Assembly of Microsystems  

Microsoft Academic Search

In the microworld, as well as in the macroworld, assembly is a crucial operation in the genesis of a product. This keynote paper focusses on the assembly problems occurring in the manufacturing cycle of microsystems. Scaling effects make that the assembly problems are different in the microworld. The different assembly operations and techniques, like manipulation by physical contact, non-contact manipulation,

H. Van Brussel; J. Peirs; D. Reynaerts; A. Delchambre; G. Reinhart; N. Roth; M. Weck; E. Zussman

2000-01-01

150

Self-Assembly Game  

NSDL National Science Digital Library

This is a quick game about self-assembly. Like the molecules of DNA, learners will self-assemble into a pattern by following a simple set of rules. The icebreaker game is part of a larger self-assembly lesson plan, and additional self-assembly game ideas and a video can be found in the related links.

Twin Cities Public Television, Inc.

2008-01-01

151

Electrical Connector Assembly.  

National Technical Information Service (NTIS)

An electrical connector assembly including a female connector assembly and a male connector assembly configured for quick push-pull connect and for squeeze-to-release disconnect. The female and male connector assemblies are each molded of a plastics mater...

H. J. Banas P. E. Moody

2001-01-01

152

Latching relay switch assembly  

DOEpatents

A latching relay switch assembly which includes a coil section and a switch or contact section. The coil section includes at least one permanent magnet and at least one electromagnet. The respective sections are, generally, arranged in separate locations or cavities in the assembly. The switch is latched by a permanent magnet assembly and selectively switched by an overriding electromagnetic assembly.

Duimstra, Frederick A. (Anaheim Hills, CA)

1991-01-01

153

The physical and chemical state of Westinghouse Phosphoric Acid Fuel Cell assemblies after long term operation: Surface and near-surface analysis  

NASA Astrophysics Data System (ADS)

An attempt was made to correlate performance losses with materials compatibility and compositional changes in Phosphoric Acid Fuel Cell (PAFC) electrode assemblies as a function of operation time. Westinghouse PAFC stacks were run under a constant operating regime and portions of some of the single cells were analysed after stack operation for 5000 and 16,000 hrs along with appropriate reference samples. The PAFC assemblies were disassembled, sectioned where appropriate and analyzed using scanning and transmission electron microscopy (SEM and TEM), Rutherford backscattering spectroscopy (RBS), electron microprobe analysis (EMP), and x ray photoelectron spectroscopy (XPS). The profiles of the Pt catalyst in both the anode and the cathode layer did not show any preferential loss or peaking. The most pronounced change in cell composition detected following stack operation for 5000 and 16,000 hours was the increase in Pt/C ratio, that was related to loss of carbon from the cathode electrocatalyst. In contrast, the anode catalyst layer maintains the same ratio of Pt/C following 16,000 hours of operation. The loss of carbon is thought to occur by an electrochemical mechanism and is enhanced at the higher potentials experienced by the air cathode in the fuel cell. In addition, TEM results clearly demonstrate the well recognized phenomenon of Pt particle agglomeration in the cathode catalyst layer, which is seen to be quite substantial after 5000 hours of stack operation. The mechanical integrity of the assemblies was found to be quite satisfactory after 5000 hours, but much less so after 16,000 hours. Questions regarding carbon and Pt corrosion, Pt migration, and the mechanical and physical integrity of the PAFC structures are addressed and are all postulated to be contributing to the observed cell performance losses.

Paffett, M. T.; Hutchinson, W.; Farr, J. D.; Papin, P.; Beery, J. G.; Gottesfeld, S.; Feret, J.

1990-03-01

154

The physical and chemical state of phosphoric acid fuel cell assemblies after long term operation: surface and near-surface analysis  

NASA Astrophysics Data System (ADS)

An attempt was made to correlate performance losses with materials compatibility and compositional changes in phosphoric acid fuel cell (PAFC) electrode assemblies as a function of operation time. Westinghouse PAFC stacks were run under a constant operating regime and portions of some of the single cells were analyzed after stack operation for 5000 and 16 000 h along with appropriate reference samples. The PAFC assemblies were disassembled, sectioned where appropriate and analyzed using scanning and transmission electron microscopy (SEM and TEM), Rutherford backscattering spectroscopy (RBS), electron microprobe analysis (EMP), and X-ray photoelectron spectroscopy (XPS). The profiles of the Pt catalyst in both the anode and the cathode layer did not show any preferential loss or peaking. The most pronounced change in cell composition detected following stack operation for 5000 and 16 000 h was the increase in Pt/C ratio, that was related to loss of carbon from the cathode electrocatalyst. In contrast, the anode catalyst layer maintains the same ratio of Pt:C following 16 000 h of operation. The loss of carbon is thought to occur by an electrochemical mechanism and is enhanced at the higher potentials experienced by the air cathode in the fuel cell. In addition, TEM results clearly demonstrate the well recognized phenomenon of Pt particle agglomeration in the cathode catalyst layer, which is seen to be quite substantial after 5000 h of stack operation. This behavior was not observed at the anode electrocatalyst layer. The mechanical integrity of the assemblies was found to be quite satisfactory after 5000 h, but much less so after 16 000 h. Questions regarding carbon and Pt corrosion, Pt migration, and the chemical and physical integrity of the PAFC structures are addressed and are all postulated to be contributing to the observed cell performance losses.

Paffett, M. T.; Hutchinson, W.; Farr, J. D.; Papin, P.; Beery, J. G.; Gottesfeld, S.; Feret, J.

155

Assembly of a Cohort of Children Treated for Acute Myeloid Leukemia at Free-Standing Children's Hospitals in the United States Using an Administrative Database  

PubMed Central

Pediatric Health Information System data were used to establish a multi-center cohort of 1,686 children treated for newly diagnosed acute myeloid leukemia (AML). The cohort assembly process, which included myeloid leukemia ICD-9 discharge diagnosis codes and manual review of induction chemotherapy, was validated by chart review at a single institution. The use of ICD-9 codes alone resulted in a poor positive predictive value (PPV; 31%). Inclusion of the results from the chemotherapy review improved the PPV to 100% without compromising sensitivity (95.7%). This cohort provides a reliable source for future comparative effectiveness and clinical epidemiology studies in pediatric AML.

Kavcic, Marko; Fisher, Brian T.; Torp, Kari; Yimei, Li; Huang, Yuan-Shung; Seif, Alix E.; Vujkovic, Marijana; Aplenc, Richard

2013-01-01

156

Evaluation and selection of assembly plans  

NASA Astrophysics Data System (ADS)

Two criteria are introduced for the evaluation and selection of assembly plans. The first criterion is to maximize the number of different sequences encompassed by the assembly plan. The second criterion is to maximize the amount of parallelism (i.e., simultaneity) that is possible in the execution of the assembly tasks. While the metrics corresponding to the criteria used in previous work can be expressed as a sum of terms, each being a function of a task or a state, the metrics corresponding to the criteria introduced are more complex functions of the whole assembly plan. An algorithm that performs a heuristic search for the best assembly plan over the AND/OR graph representation of assembly plans introduced in previous work is presented. Admissible heuristics for each of the two criteria are presented.

Homem de Mello, L. S.; Sanderson, A. C.

157

Adaptive Accommodation Control Method for Complex Assembly  

NASA Astrophysics Data System (ADS)

Robotic systems have been used to automate assembly tasks in manufacturing and in teleoperation. Conventional robotic systems, however, have been ineffective in controlling contact force in multiple contact states of complex assemblythat involves interactions between complex-shaped parts. Unlike robots, humans excel at complex assembly tasks by utilizing their intrinsic impedance, forces and torque sensation, and tactile contact clues. By examining the human behavior in assembling complex parts, this study proposes a novel geometry-independent control method for robotic assembly using adaptive accommodation (or damping) algorithm. Two important conditions for complex assembly, target approachability and bounded contact force, can be met by the proposed control scheme. It generates target approachable motion that leads the object to move closer to a desired target position, while contact force is kept under a predetermined value. Experimental results from complex assembly tests have confirmed the feasibility and applicability of the proposed method.

Kang, Sungchul; Kim, Munsang; Park, Shinsuk

158

Spatially controlled reversible colloidal self-assembly  

NASA Astrophysics Data System (ADS)

We studied the localized self-assembly of colloidal crystals on a topographically patterned substrate. A competition between particle and pattern interactions provided the ability to reversibly assemble quasi-two-dimensional colloidal crystals on a periodic landscape. The assembly process was visualized and controlled in real-space and real-time using video microscopy. Independent measurements and computer simulations were used to quantify all interactions controlling self-assembly. Steady-state studies characterized spatially inhomogeneous, coexisting fluid and crystal microstructures at various stages of assembly. Microstructures arise from a balance of local sedimentation equilibria within potential energy features and a tunable pairwise depletion attraction between colloids. Transient colloidal crystal self-assembly occurred via a quasiequilibrium process as characterized by continuously evolving spatial profiles of local density, bond orientational order, and self-diffusivities.

Fernandes, Gregory E.; Beltran-Villegas, Daniel J.; Bevan, Michael A.

2009-10-01

159

Inlet nozzle assembly  

DOEpatents

An inlet nozzle assembly for directing coolant into the duct tube of a fuel assembly attached thereto. The nozzle assembly includes a shell for housing separable components including an orifice plate assembly, a neutron shield block, a neutron shield plug, and a diffuser block. The orifice plate assembly includes a plurality of stacked plates of differently configurated and sized openings for directing coolant therethrough in a predesigned flow pattern.

Christiansen, David W. (Kennewick, WA); Karnesky, Richard A. (Richland, WA); Precechtel, Donald R. (Richland, WA); Smith, Bob G. (Richland, WA); Knight, Ronald C. (Richland, WA)

1987-01-01

160

Inlet nozzle assembly  

DOEpatents

An inlet nozzle assembly for directing coolant into the duct tube of a fuel assembly attached thereto. The nozzle assembly includes a shell for housing separable components including an orifice plate assembly, a neutron shield block, a neutron shield plug, and a diffuser block. The orifice plate assembly includes a plurality of stacked plates of differently configurated and sized openings for directing coolant therethrough in a predesigned flow pattern.

Christiansen, D.W.; Karnesky, R.A.; Knight, R.C.; Precechtel, D.R.; Smith, B.G.

1985-09-09

161

Emergent multistability in assembled nanostructures.  

PubMed

Scanning tunneling microscopy (STM) at 5 K reveals that native atoms in the surface layer of a semiconductor crystal become bistable in vertical height when a nanostructure is assembled nearby. The binary switching of surface atoms, driven by the STM tip, changes their charge state. Coupling is facilitated by assembling adatom chains, allowing us to explore the emergence of complex multiple switching. Density-functional theory calculations rationalize the observations and a lattice-gas model predicts the cooperative behavior from first principles. PMID:21591678

Yang, Jianshu; Erwin, Steven C; Kanisawa, Kiyoshi; Nacci, Christophe; Fölsch, Stefan

2011-06-01

162

Designing electron wave functions in assembled nanostructures  

Microsoft Academic Search

We use the scanning tunneling microscope to not only to map electron wave functions but also to engineer them. By assembling nanostructures from individual atoms and molecules, we confine two-dimensional electronic states into closed electron resonators, or \\

Christopher Ryan Moon

2009-01-01

163

OSU Team Assembles X-Hab Loft  

NASA Video Gallery

This time lapse video shows the Oklahoma State University team in the process of assembling and inflating the loft they've built for the first X-Hab Academic Innovation Challenge. OSU is one of thr...

164

High Resolution Mirror Assembly: The Assembly Challenges  

NASA Astrophysics Data System (ADS)

During the integration of the High Resolution Mirror Assembly (HRMA), a continuous learning process was adopted. Each step in the process provided critical insight into how the future assembly would operate. Process development was on-going as more was learned during the assembly effort at ITT. This poster will provide a overview of the lessons learned and the process development that took place to enable the HRMA to meet all performance criteria on-orbit.

Matthews, Gary; Atkinson, Charlie

2009-09-01

165

Kinetics of assembly and dissociation of the mitochondrial creatine kinase octamer. A fluorescence study.  

PubMed

The dissociation of octameric mitochondrial creatine kinase (Mi-CK) into dimers induced by the transition-state analogue complex (TSAC) mixture (creatine+Mg(2+)+ADP+NO3-) is accompanied by a large (25.2%) decrease in Trp fluorescence. This effect is caused by a Trp residue situated at the dimer-dimer interface within the octamer, which becomes susceptible to solvent quenching upon octamer dissociation. Octamer formation, induced by adding excess EDTA to TSAC-dissociated Mi-CK, involves a transient tetrameric species, whereas the dissociation reaction proceeds in a one-step, all-or-none fashion. From fluorescence spectroscopic investigations of the octamer formation and dissociation reactions, a first-order dissociation rate constant of 0.19 min-1 and a bimolecular association rate constant of 318 M-1 s-1 at 30 degrees C were obtained. The octamers formed after EDTA addition can be dissociated again by lowering the temperature to 4 degrees C, indicating a substantial hydrophobic contribution to the interactions stabilizing the octamer. PMID:8268169

Gross, M; Wallimann, T

1993-12-21

166

Firearm trigger assembly  

DOEpatents

A firearm trigger assembly for use with a firearm includes a trigger mounted to a forestock of the firearm so that the trigger is movable between a rest position and a triggering position by a forwardly placed support hand of a user. An elongated trigger member operatively associated with the trigger operates a sear assembly of the firearm when the trigger is moved to the triggering position. An action release assembly operatively associated with the firearm trigger assembly and a movable assembly of the firearm prevents the trigger from being moved to the triggering position when the movable assembly is not in the locked position.

Crandall, David L. (Idaho Falls, ID); Watson, Richard W. (Blackfoot, ID)

2010-02-16

167

Seal assembly releasing tool  

SciTech Connect

A seal assembly releasing tool is shown having an outer support case and an inner unlocking element rotatably mounted on a shaft and coupled by a planetary gear train. The seal assembly is provided with cam surfaces into which cam followers latch for securely connecting the tool to the seal assembly and enabling the outer case to turn the assembly in one direction while the inner element turns the locking sleeve of the seal assembly in the other direction to release the seal assembly.

Woodman, D.C.

1984-02-14

168

Unprecedented formation of a hydrogen-bonded assembly of water-diethylenetriamine molecules within a new solid state supramolecular molybdenum(V) phosphate complex  

NASA Astrophysics Data System (ADS)

An unprecedented H-bonded 2-D arrangement consisting of water dimers, V-shaped water trimers and protonated diethylenetriamine (deta) molecules is crystallographically characterized for the first time in the host crystal lattice of a new reduced molybdenum(V) phosphates [Hdeta]4{Na[NaMo12VO(OH)6(HPO)2(HPO)4(PO)2]}·8HO which is prepared under hydrothermal condition and characterized by elemental analyses, IR, UV-Vis, TG-DTA, cyclic voltammetry and single-crystal X-ray diffraction. The harmonious assembly of the small dimer and trimer water clusters and deta molecules is significant in stabilizing and influencing the arrangement of their surroundings which herein refers to the 1-D inorganic anion chains constructed by the versatile building blocks of the formula [Mo 6P 4O 31] covalently connected with NaO 6 octahedra, giving rise to a 3-D arrays via complex hydrogen bonding interactions.

Zhang, Lijuan; Li, Xianqi; Zhou, Yunshan; Wang, Xuan

2009-06-01

169

Identification of functional regions on the tail of Acanthamoeba myosin- II using recombinant fusion proteins. II. Assembly properties of tails with NH2- and COOH-terminal deletions  

PubMed Central

We used purified fusion proteins containing parts of the Acanthamoeba myosin-II tail to localize those regions of the tail responsible for each of the three steps in the successive dimerization mechanism (Sinard, J. H., W. F. Stafford, and T. D. Pollard. 1989. J. Cell Biol. 107:1537-1547) for Acanthamoeba myosin-II minifiliment assembly. Fusion proteins containing the terminal approximately 90% of the myosin-II tail assemble normally, but deletions within the last 100 amino acids of the tail sequence alter or prevent assembly. The first step in minifilament assembly, formation of antiparallel dimers, requires the COOH-terminal approximately 30 amino acids that are thought to form a nonhelical domain at the end of the coiled-coil. The second step, formation of antiparallel tetramers, requires the last approximately 40 residues in the coiled-coil. The final step, the association of two antiparallel tetramers to form the completed octameric minifilament, requires residues approximately 40-70 from the end of the coiled-coil. A region of the tail near the junction with the heads is important for tight packing of the tails in the minifilaments. Divalent cations induce the lateral aggregation of minifilaments formed from native myosin-II or fusion proteins containing a nonmyosin "head," but under the same conditions fusion proteins composed essentially only of myosin tail sequences with very little nonmyosin sequences form paracrystals. The region of the tail necessary for this paracrystal formation lies NH2-terminal to amino acid residue 1,468 in the native myosin-II sequence.

1990-01-01

170

Solar heat collector assembly  

SciTech Connect

A solar heat collector assembly includes a cylindrical transparent tube having an open end portion hermetically sealed by the use of a sealant and being held in vacuum state and a heat-collecting pipe secured in the transparent tube with its end portion extending outside the transparent tube through the sealant. The sealant of a transparent material, for example, is bowl-shaped and the heat-collecting pipe is secured to pass through the center of the bowl-shaped sealant. The pipe and the sealant are bonded together through the use of a proper adhesive metal material. The outer periphery of the sealant is further bonded to the open end portion of the transparent tube. The adhesive metal material is typically 426 alloy.

Tonomura, T.; Katto, A.; Shimada, M.; Takeishi, K.

1983-11-08

171

Saddle Clamp Assembly.  

National Technical Information Service (NTIS)

A saddle clamp assembly is presented. The assembly is comprised of a hollow cylindrical body centered about a longitudinal axis and being diametrically split into semicircular top and bottom sections. Each section has a pair of connection flanges, at oppo...

C. R. Belrose

1992-01-01

172

Fuel assembly locking apparatus  

SciTech Connect

The fuel assembly locking apparatus comprises a rotatable plate capable of simultaneously and positively engaging all four legs of the bottom nozzle of a fuel assembly for uniformly holding the fuel assembly while the spent fuel rods are pulled from the fuel assembly. The rotatable plate has four notched corners arranged to be rotated over a ledge on each leg of the bottom nozzle of the fuel assembly thereby preventing movement of the fuel assembly. The rotatable plate is also capable of being rotated 45/sup 0/ so that the four corners of the plate are rotated clear of the legs of the bottom nozzle of the fuel assembly thereby allowing the fuel assembly to be placed on or removed from the locking apparatus. The locking apparatus is also provided with a torque actuator for remotely rotating the plate.

Tolino, R. W.; Toler Sr., C. E.

1984-10-02

173

Free-energy landscape for peptide amphiphile self-assembly: stepwise versus continuous assembly mechanisms.  

PubMed

The mechanism of self-assembly of 140 peptide amphiphiles (PAs) to give nanofiber structures was investigated using a coarse-grained method to quantitatively determine whether the assembly process involves discrete intermediates or is a continuous process. Two novel concepts are introduced for this analysis, a cluster analysis of the time dependence of PA assembly and use of the fraction of native contacts as reaction coordinates for characterizing thermodynamic functions during assembly. The cluster analysis of the assembly kinetics demonstrates that a pillar-like intermediate state is formed before the final cylindrical semifiber structure. We also find that head group assembly occurs on a much shorter time scale than tail group assembly. A 2D free-energy landscape with respect to the fraction of native contacts was calculated, and the pillar-like intermediate structure was also found, with free energies about 1.2 kcal/mol higher than the final state. Although this intermediate state exists for only hundreds of nanoseconds, the PA self-assembly process can be recognized as involving two steps, (a) transition from the disordered state to the noncylindrical pillar-like intermediate and (b) pillar-like to final semifiber transition. These results are important to the further design of PAs as functional nanostructures. PMID:24143994

Yu, Tao; Schatz, George C

2013-11-14

174

State  

Microsoft Academic Search

\\u000a The notion of state is fundamental to the design and analysis of virtually all computational systems. The Myhill-Nerode Theorem\\u000a of Finite Automata theory—and the concepts underlying the Theorem—is a source of sophisticated fundamental insights about\\u000a a large class of state-based systems, both finite-state and infinite-state systems. The Theorem’s elegant algebraic characterization\\u000a of the notion of state often allows one to

Arnold L. Rosenberg

2006-01-01

175

Membrane module assembly  

DOEpatents

A membrane module assembly is described which is adapted to provide a flow path for the incoming feed stream that forces it into prolonged heat-exchanging contact with a heating or cooling mechanism. Membrane separation processes employing the module assembly are also disclosed. The assembly is particularly useful for gas separation or pervaporation. 2 figures.

Kaschemekat, J.

1994-03-15

176

Cage redesign explains assembly  

PubMed Central

Control of protein self-assembly and disassembly, which is central to metabolism and engineering applications, remains challenging. Here, a perspicacious redesign of interfaces in the multisubunit ferritin protein cage provides single, modifiable subunits that assemble with Cu2+ templating and give insights into the cage assembly code.

Theil, Elizabeth C; Turano, Paola

2013-01-01

177

Managing Coil Epoxy Vacuum Impregnation Systems at the Manufacturing Floor Level to Achieve Ultimate Properties in State of the Art Magnet Assemblies.  

National Technical Information Service (NTIS)

Liquid epoxy resin impregnation systems remain a state-of-the-art polymer material for vacuum and vacuum/pressure impregnation applications in the manufacture of both advanced and conventional coil winding configurations. Epoxy resins inherent latitude in...

J. G. Hubrig G. H. Biallas

2005-01-01

178

Telerobotic truss assembly  

NASA Technical Reports Server (NTRS)

The ACCESS truss was telerobotically assembled in order to gain experience with robotic assembly of hardware designed for astronaut extravehicular (EVA) assembly. Tight alignment constraints of the ACCESS hardware made telerobotic assembly difficult. A wider alignment envelope and a compliant end effector would have reduced the problem. The manipulator had no linear motion capability, but many of the assembly operations required straight line motion. The manipulator was attached to a motion table in order to provide the X, Y, and Z translations needed. A programmable robot with linear translation capability would have eliminated the need for the motion table and streamlined the assembly. Poor depth perception was a major problem. Shaded paint schemes and alignment lines were helpful in reducing this problem. The four cameras used worked well for only some operations. It was not possible to identify camera locations that worked well for all assembly steps. More cameras or movable cameras would have simplified some operations. The audio feedback system was useful.

Sheridan, Philip L.

1987-01-01

179

Frameless enclosure assembly  

US Patent & Trademark Office Database

A frameless enclosure assembly, supported by the structural assembly of a pre-engineered building having first and second support members, comprising a flexible membrane; a membrane attaching assembly attaching a first end of the facing membrane to the first support member, and attaching a second end of the facing membrane to the second support member and extending the facing membrane substantially taut therebetween; an insulation layer of compressible insulation material supported by the facing membrane; a panel member positioned substantially parallel to the insulation layer to dispose same between the panel member and underlaying structural assembly; and a panel securing assembly for securing the panel to the structural assembly and transferring load from the panel member to the structural assembly while the insulation layer substantially uniformly retains its resistance to heat transfer.

1982-12-07

180

Composite fan stator assembly  

SciTech Connect

A composite fan stator assembly is described for a gas turbine engine having at least two fan rotor stages, the composite stator assembly comprising: an annular composite fan case assembly including an access port, the fan case assembly circumferentially disposed around first and second fan rotor stage locations, a composite fan stator stage supported by and extending radially inward of the fan case assembly and axially disposed between the two fan rotor stage locations, the fan stator stage includes at least one removable vane segment accessible for removal through the access port for assembly and reassembly, the composite fan case assembly including a separable composite forward fan case assembly and a separable composite aft fan case assembly spaced axially aft of the forward fan case assembly, the forward fan case assembly being bolted to the aft fan case assembly, wherein the composite fan stator stage is axially and radially trapped and supported by the forward and aft fan case assemblies. A composite stator vane assembly comprising: a composite inner shroud, a composite outer shroud disposed radially outward of the inner shroud, a plurality of vanes disposed between the shrouds, the vanes including a suction side and a pressure side and radially inner and outer roots, the roots extending through platforms of corresponding ones of the inner and outer shrouds, four box-type attachment elements corresponding to curved suction and pressure sides of the inner and outer roots, the box-type attachment elements having two connected legs angled with respect to each other, a first one of the legs extending along, conforming to the curve of, and bonded to a corresponding one of the airfoil root sides, and a second one of the legs extending along and bonded to a composite shroud surface.

Donges, G.L.

1993-07-13

181

Assembly of MultiElement, Ultra Low Background, Germanium Spectrometer for Two Neutrino Double Beta Decay to the Excited State and Materials Assay  

Microsoft Academic Search

Envisioned array of 16 70 percent, plus two, Germanium detectors with one being a 85 percent ^76Ge enriched detector. Efforts over the past ten to fifteen years in radio purity, shielding, and pulse shape discrimination come to bear. Technology and experience from previous experiments like the International Germanium Experiment (IGEX). This array will explore excited state double beta decay, in

Jeremy Kephart

2003-01-01

182

Molecular Self-Assembly  

SciTech Connect

This report is divided into two parts: a study of the glass transition in confined geometries, and formation mechanisms of block copolymer mesophases by solvent evaporation-induced self-assembly. The effect of geometrical confinement on the glass transition of polymers is a very important consideration for applications of polymers in nanotechnology applications. We hypothesize that the shift of the glass transition temperature of polymers in confined geometries can be attributed to the inhomogeneous density profile of the liquid. Accordingly, we assume that the glass temperature in the inhomogeneous state can be approximated by the Tg of a corresponding homogeneous, bulk polymer, but at a density equal to the average density of the inhomogeneous system. Simple models based on this hypothesis give results that are in remarkable agreement with experimental measurements of the glass transition of confined liquids. Evaporation-induced self-assembly (EISA) of block copolymers is a versatile process for producing novel, nanostructured materials and is the focus of much of the experimental work at Sandia in the Brinker group. In the EISA process, as the solvent preferentially evaporates from a cast film, two possible scenarios can occur: microphase separation or micellization of the block copolymers in solution. In the present investigation, we established the conditions that dictate which scenario takes place. Our approach makes use of scaling arguments to determine whether the overlap concentration c* occurs before or after the critical micelle concentration (CMC). These theoretical arguments are used to interpret recent experimental results of Yu and collaborators on EISA experiments on Silica/PS-PEO systems.

CURRO, JOHN G.; MCCOY, JOHN DWANE; FRISCHKNECHT, AMALIE L.; YU, KUI

2001-11-01

183

Precedence relationship representations of mechanical assembly sequences  

NASA Technical Reports Server (NTRS)

Two types of precedence relationship representations for mechanical assembly sequences are presented: precedence relationships between the establishment of one connection between two parts and the establishment of another connection, and precedence relationships between the establishment of one connection and states of the assembly process. Precedence relationship representations have the advantage of being very compact. The problem with these representations was how to guarantee their correctness and completeness. Two theorems are presented each of which leads to the generation of one type of precedence relationship representation guaranteeing its correctness and completeness for a class of assemblies.

Homendemello, L. S.; Sanderson, A. C.

1989-01-01

184

Photovoltaic assemblies and methods for transporting  

DOEpatents

A PV assembly including framework, PV laminate(s), and a stiffening device. The framework includes a perimeter frame at least 10 feet in length and at least 5 feet in width. The PV laminate(s) are assembled to the perimeter frame to define a receiving zone having a depth of not more than 8 inches. The stiffening device is associated with the framework and is configured to provide a first state and a second state. In the first state, an entirety of the stiffening device is maintained within the receiving zone. In the second state, at least a portion of the stiffening device projects from the receiving zone. The stiffening device enhances a stiffness of the PV assembly in a plane of the perimeter frame, and can include rods defining truss structures.

Almy, Charles; Campbell, Matt; Sandler, Reuben; Wares, Brian; Wayman, Elizabeth

2013-09-17

185

Optical orientation and alignment of excitons in self-assembled CdSe\\/ZnSe quantum dots: The role of excited states  

Microsoft Academic Search

We studied the optical orientation of excitons in an ensemble of self-organized CdSe\\/ZnSe quantum dots (QDs) via photoluminescence (PL) under quasiresonant excitation. The observed PL spectra clearly show the high efficiency of phonon-assisted emission processes. The results demonstrate unambiguously that the QD symmetry is lower than D2d , which results in the splitting of optically active exciton states into two

Yu. G. Kusrayev; A. V. Koudinov; B. P. Zakharchenya; S. Lee; J. K. Furdyna; M. Dobrowolska

2005-01-01

186

State of metallic surfaces in systems of nuclear power plants with a series 1000 high-powered-water-cooled channel reactor after assembly  

Microsoft Academic Search

We investigated the state of the surfaces by examining, photographing, and collecting samples of surface contaminants at the open ends of piping system blocks. We performed a phase analysis of the samples taken in a 3,-resonance YaGRS-4M spectrometer. We determined the specific contamination of the inner surfaces of equipment and piping system by a weight method by mechanically removing oxides

V. M. Sedov; P. G. Krutikov; A. I. Grushanin; S. T. Zolotukhin; Yu. O. Zakharzhevskii; A. P. Eperin

1981-01-01

187

New designed protein assemblies.  

PubMed

Self-assembly is an essential concept of all organisms. Polypeptides self-assemble either within a single polypeptide chain or through assembly of protein domains. Recent advances in designed protein assemblies were achieved by genetic or chemical linkage of oligomerization domains and by engineering new interaction interfaces, which resulted in formation of lattices and cage-like protein assemblies. The absence of new experimentally determined protein folds in the last few years underlines the challenge of designing new folds. Recently a new strategy for designing self-assembly of a polypeptide fold, based on the topological arrangement of coiled-coil modules as the protein origami, has been proposed. The polypeptide tetrahedron was designed from a single chain concatenating of coiled-coil forming building modules interspersed with flexible hinges. In this strategy the order of coiled-coil segments defines the fold of the polypeptide nanostructure. PMID:24183814

Boži?, Sabina; Doles, Tibor; Gradišar, Helena; Jerala, Roman

2013-12-01

188

Assembly chaperones: a perspective  

PubMed Central

The historical origins and current interpretation of the molecular chaperone concept are presented, with the emphasis on the distinction between folding chaperones and assembly chaperones. Definitions of some basic terms in this field are offered and misconceptions pointed out. Two examples of assembly chaperone are discussed in more detail: the role of numerous histone chaperones in fundamental nuclear processes and the co-operation of assembly chaperones with folding chaperones in the production of the world's most important enzyme.

Ellis, R. John

2013-01-01

189

Ordering self-assembled nanostructures  

NASA Astrophysics Data System (ADS)

Many innovative applications of nanosciences, such as semiconductor lasers, quantum computing, information storage, quantum cryptography, and semiconductor transistors largely rely on the ability to fabricate long-range ordered nanostructures. However, conventional top-down techniques have mostly reached a bottleneck that thwarts the progress toward future miniaturization needed for the next generation of nanodevices. This constraint imposes the need to develop new manufacturing methods to engineering nanodevices on the single-digit-nanometer scale. Self-assembly, the spontaneous formation of regular arrays, is emerging as one of the most promising avenues for both miniaturization and fabrication. While self-assembly can bring us the direct large scale fabrication of nanostructures, the stochastic nature stemming from symmetry breaking bifurcation inhibits the full realization of ordered nano-arrays. Since the quality of electronic, optical, magnetic and photonic properties of nanodevices depends substantially on the uniformity of their arrangement, avoiding imperfections in self-assembly is important; thus forms the central subject of this dissertation. We propose a method for ordering self-assembled nanostructures by imposing control on the deposition using an opaque mask placed a finite distance above the substrate. This choice is motivated by studies of symmetry breaking, which suggest that boundary conditions provide a means to select among all possible broken symmetry states. We have conducted both linear and nonlinear stability analyses to derive optimal control parameters that support specific pattern formation. Numerical integrations of two morphological self-assembly models (2D biphasic surface islands in a monolayer and 3D epitaxial quantum dot growth in Stranski-Krastanow mode) show that the proposed method can indeed give large scale, well organized nanostructures.

Shi, Feng

190

Linux Assembly HOWTO  

NSDL National Science Digital Library

This tutorial "describes how to program in assembly language using free programming tools, focusing on development for or from the Linux Operating System." For applications that are closely related to the underlying computer architecture, assembly language programming can be very important. The instructive material is aimed at people who have at least a basic understanding of conventional, high-level programming styles but have little to no experience with assembly. Hence, it serves as a general introduction to the topic, mainly useful for understanding what situations lend themselves to assembly programming.

Boldyshev, Konstantin.; Rideau, Francois-Rene.

191

Ex vivo DNA Assembly  

PubMed Central

Even with decreasing DNA synthesis costs there remains a need for inexpensive, rapid, and reliable methods for assembling synthetic DNA into larger constructs or combinatorial libraries. Advances in cloning techniques have resulted in powerful in vitro and in vivo assembly of DNA. However, monetary and time costs have limited these approaches. Here, we report an ex vivo DNA assembly method that uses cellular lysates derived from a commonly used laboratory strain of Escherichia coli for joining double-stranded DNA with short end homologies embedded within inexpensive primers. This method concurrently shortens the time and decreases costs associated with current DNA assembly methods.

Fisher, Adam B.; Canfield, Zachary B.; Hayward, Laura C.; Fong, Stephen S.; McArthur, George H.

2013-01-01

192

8-Hydroxypyrene-1,3,6-trisulphonate and octanesulphonate co-assembled layered double hydroxide and its controllable solid-state luminescence by hydrothermal synthesis  

NASA Astrophysics Data System (ADS)

8-Hydroxy-pyrene-1,3,6-trisulphonate (HPTS) and octanesulphonate (OS) have been co-intercalated into the ZnAl layered double hydroxide (LDH) host by a hydrothermal co-precipitation method, with samples denoted as HPTS ( x%)-OS/Zn 2Al-LDH ( x stands for the molar percentage content of HPTS with respect to total amount of HPTS and OS). The structure and chemical compositions of the as-prepared compounds were characterized by X-ray diffraction (XRD) and elemental analysis. The steady-state and time-decay fluorescent studies show that HPTS (2%)-OS/Zn 2Al-LDH has the optimal luminous emission and the longest fluorescent lifetime. Moreover, these samples exhibit controllable dual fluorescence between the blue and green regions upon changing the interlayer HPTS content, external pH values, and host-guest interaction, illustrating that these organic-inorganic samples have potential application in the field of tunable solid luminescent materials.

Dang, Sile; Yan, Dongpeng; Lu, Jun

2012-01-01

193

Self-Assembly  

NSDL National Science Digital Library

Self-assembly is the process of matter organizing autonomously and without human intervention (Whitesides, Mathias, and Seto 1991; Withesides and Boncheva 2002). The process of self-assembly can be introduced in a range of contexts in the natural and appl

Krajcik, Joseph S.; Sutherland, Leeann M.; Stevens, Shawn Y.

2009-10-14

194

Assembled MEMS VOA  

Microsoft Academic Search

Micromirrors are assembled onto actuator sockets using MEMS assembly techniques to realize a shutter and beam steering VOA. The shutter mirror moves more than 45 microns at 10.6 volts and the angular mirror rotates 4.85° at 8.32 volts.

R. Saini; A. Geisberger; K. Tsui; C. Nistorica; M. Ellis; G. Skidmore

2003-01-01

195

Turbine disc sealing assembly  

DOEpatents

A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

Diakunchak, Ihor S.

2013-03-05

196

Maximum Likelihood Genome Assembly  

Microsoft Academic Search

Whole genome shotgun assembly is the process of taking many short sequenced segments (reads) and reconstructing the genome from which they originated. We demonstrate how the technique of bidirected network flow can be used to explicitly model the double-stranded nature of DNA for genome assembly. By combining an algorithm for the Chinese Postman Problem on bidirected graphs with the construction

Paul Medvedev; Michael Brudno

2009-01-01

197

Assembly oriented design  

Microsoft Academic Search

Product design is still commonly component rather than assembly oriented. Industry requirements have inspired a more holistic approach which is presented here. In this, proactive DFA is used in a process centred around assembly sequence construction. Early analysis and evaluation is enabled by geometric reasoning and expert system tools. Details of underlying principles and implementation are given together with a

C. J. Barnes; G. F. Dalgleish; G. E. M. Jared; H. Mei; K. G. Swift

1999-01-01

198

Liquid rocket valve assemblies  

NASA Technical Reports Server (NTRS)

The design and operating characteristics of valve assemblies used in liquid propellant rocket engines are discussed. The subjects considered are as follows: (1) valve selection parameters, (2) major design aspects, (3) design integration of valve subassemblies, and (4) assembly of components and functional tests. Information is provided on engine, stage, and spacecraft checkout procedures.

1973-01-01

199

Automated assembly in space  

NASA Technical Reports Server (NTRS)

The installation of robots and their use of assembly in space will create an exciting and promising future for the U.S. Space Program. The concept of assembly in space is very complicated and error prone and it is not possible unless the various parts and modules are suitably designed for automation. Certain guidelines are developed for part designing and for an easy precision assembly. Major design problems associated with automated assembly are considered and solutions to resolve these problems are evaluated in the guidelines format. Methods for gripping and methods for part feeding are developed with regard to the absence of gravity in space. The guidelines for part orientation, adjustments, compliances and various assembly construction are discussed. Design modifications of various fasteners and fastening methods are also investigated.

Srivastava, Sandanand; Dwivedi, Suren N.; Soon, Toh Teck; Bandi, Reddy; Banerjee, Soumen; Hughes, Cecilia

1989-01-01

200

Packer and service tool assembly  

SciTech Connect

This patent describes a gravel packer assembly and service tool. It includes a hydraulically actuable coupling for connecting and disconnecting the gravel packer assembly with the service tool for assembled use in a well.

Scranton, J.D.

1989-09-05

201

Self-assembled plasmonic metamaterials  

NASA Astrophysics Data System (ADS)

Nowadays for the sake of convenience most plasmonic nanostructures are fabricated by top-down nanofabrication technologies. This offers great degrees of freedom to tailor the geometry with unprecedented precision. However, it often causes disadvantages as well. The structures available are usually planar and periodically arranged. Therefore, bulk plasmonic structures are difficult to fabricate and the periodic arrangement causes undesired effects, e.g., strong spatial dispersion is observed in metamaterials. These limitations can be mitigated by relying on bottom-up nanofabrication technologies. There, self-assembly methods and techniques from the field of colloidal nanochemistry are used to build complex functional unit cells in solution from an ensemble of simple building blocks, i.e., in most cases plasmonic nanoparticles. Achievable structures are characterized by a high degree of nominal order only on a short-range scale. The precise spatial arrangement across larger dimensions is not possible in most cases; leading essentially to amorphous structures. Such self-assembled nanostructures require novel analytical means to describe their properties, innovative designs of functional elements that possess a desired near- and far-field response, and entail genuine nanofabrication and characterization techniques. Eventually, novel applications have to be perceived that are adapted to the specifics of the self-assembled nanostructures. This review shall document recent progress in this field of research. Emphasis is put on bottom-up amorphous metamaterials. We document the state-of-the-art but also critically assess the problems that have to be overcome.

Mühlig, Stefan; Cunningham, Alastair; Dintinger, José; Scharf, Toralf; Bürgi, Thomas; Lederer, Falk; Rockstuhl, Carsten

2013-07-01

202

Cluster-assembled metallic glasses  

PubMed Central

A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure–property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure–property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials.

2013-01-01

203

Dynamic Nanoparticles Assemblies  

PubMed Central

CONSPECTUS Importance Although nanoparticle (NP) assemblies are at the beginning of their development, their unique geometrical shapes and media-responsive optical, electronic and magnetic properties have attracted significant interest. Nanoscale assembly bridges multiple sizes of materials: individual nanoparticles, discrete molecule-like or virus-like nanoscale agglomerates, microscale devices, and macroscale materials. The capacity to self-assemble can greatly facilitate the integration of nanotechnology with other technologies and, in particular, with microscale fabrication. In this Account, we describe developments in the emerging field of dynamic NP assemblies, which are spontaneously formed superstructures containing more than two inorganic nanoscale particles that display ability to change their geometrical, physical, chemical, and other attributes. In many ways, dynamic assemblies can represent a bottleneck in the ‘bottom-up’ fabrication of NP-based devices because they can produce a much greater variety of assemblies, but they also provide a convenient tool for variation of geometries and dimensions of nanoparticle assemblies. Classification Superstructures of NPs (and those held together by similar intrinsic forces) are classified into two groups: Class 1 where media and external fields can alter shape, conformation, and order of stable superstructures with a nearly constant number same. The future development of successful dynamic assemblies requires understanding the equilibrium in dynamic NP systems. The dynamic nature of Class 1 assemblies is associated with the equilibrium between different conformations of a superstructure and is comparable to the isomerization in classical chemistry. Class 2 assemblies involve the formation and/or breakage of linkages between the NPs, which is analogous to the classical chemical equilibrium for the formation of a molecule from atoms. Finer classification of NP assemblies in accord with established conventions in the field may include different size dimensionalities: discrete assemblies (artificial molecules), one-dimensional (spaced chains) and two-dimensional (sheets) and three-dimensional (superlattices, twisted structures) assemblies. Notably, these dimensional attributes must be regarded as primarily topological in nature because all of these superstructures can acquire complex three-dimensional shapes. Preparation We discuss three primary strategies used to prepare NP superstructures: (1) anisotropy-based assemblies utilizing either intrinsic force field anisotropy around NPs or external anisotropy associated with templates and/or applied fields; (2) assembly methods utilizing uniform NPs with isotropic interactions; and (3) methods based on mutual recognition of biomolecules, such as DNA and antigen-antibody interactions. Applications We consider optical, electronic, and magnetic properties of dynamic superstructures, focusing primarily on multiparticle effects in NP superstructures as represented by surface plasmon resonance, NP-NP charge transport, and multibody magnetization. Unique properties of NP superstructures are being applied to biosensing, drug delivery, and nanoelectronics. For both Class 1 and Class 2 dynamic assemblies, biosensing is the most dominant and well-developed area of dynamic nanostructures being successfully transitioned into practice. We can foresee the rapid development of dynamic NP assemblies toward applications in harvesting of dissipated energy, photonics, and electronics. The final part of the review is devoted to the fundamental questions facing dynamic assemblies of NPs in the future.

WANG, LIBING; XU, LIGUANG; KUANG, HUA; XU, CHUANLAI; KOTOV, NICHOLAS A.

2012-01-01

204

Supramolecular concepts in self-assembly of complex polymer systems  

Microsoft Academic Search

We discuss the complexation, the self-assembly behaviour and nanostructures obtained in comb-like liquid crystalline polymers formed by ionic complexation of cationic dendronized polymers and anionic lipids. The resulting self-assembled materials exhibit thermotropic liquid crystalline behaviour and a rich state diagram. The topology of the LC phases resulting from the self-assembly process, their lattice parameter and the distribution of polymer and

Raffaele Mezzenga

2007-01-01

205

Protective helmet assembly  

NASA Technical Reports Server (NTRS)

The invention is a protective helmet assembly with improved safety and impact resistance, high resistance to ignition and combustion, and reduced offgassing. The assembly comprises a hard rigid ballistic outer shell with one or more impact absorbing pads fitted to the interior surface. The pads are made of open cell flexible polyimide foam material, each of which is attached to the inner surface of the ballistic outer shell by cooperative VELCRO fastener strips of hook-and-loop material affixed respectively to the rigid outer shell and the impact absorbing pads. The helmet assembly with shell and pads is sized to fit relatively close over a wearer's head.

Dawn, Frederic S. (inventor); Weiss, Fred R. (inventor); Eck, John D. (inventor)

1992-01-01

206

SUMC reconfigurable micro-assembler  

NASA Technical Reports Server (NTRS)

The development of a reconfigurable micro-assembler to provide the micro-programmer the capability to specify micro-instructions in concise, meaningful terms is discussed. The implementation plan for the development of the micro-assembler was predicted on the existing capabilities of the SUMC Reconfigurable Assembler. Utilizing the reconfigurable assembler as a base, new directives and existing directive modifications were implemented to provide the micro-assembly as a new capability of the reconfigurable assembler. The micro-assembler language allows the specification of all micro-instruction control field settings in one concise assembler source statement. The language appears very similar to a conventional machine instruction assembler language. The machine instruction assembler language has the characteristic of one operation specification per statement whereas, the micro-instruction assembler language allows multiple operations to be designated per statement.

Edwards, A. J.

1973-01-01

207

Steam separator latch assembly  

DOEpatents

A latch assembly removably joins a steam separator assembly to a support flange disposed at a top end of a tubular shroud in a nuclear reactor pressure vessel. The assembly includes an annular head having a central portion for supporting the steam separator assembly thereon, and an annular head flange extending around a perimeter thereof for supporting the head to the support flange. A plurality of latches are circumferentially spaced apart around the head flange with each latch having a top end, a latch hook at a bottom end thereof, and a pivot support disposed at an intermediate portion therebetween and pivotally joined to the head flange. The latches are pivoted about the pivot supports for selectively engaging and disengaging the latch hooks with the support flange for fixedly joining the head to the shroud or for allowing removal thereof. 12 figures.

Challberg, R.C.; Kobsa, I.R.

1994-02-01

208

Steam separator latch assembly  

DOEpatents

A latch assembly removably joins a steam separator assembly to a support flange disposed at a top end of a tubular shroud in a nuclear reactor pressure vessel. The assembly includes an annular head having a central portion for supporting the steam separator assembly thereon, and an annular head flange extending around a perimeter thereof for supporting the head to the support flange. A plurality of latches are circumferentially spaced apart around the head flange with each latch having a top end, a latch hook at a bottom end thereof, and a pivot support disposed at an intermediate portion therebetween and pivotally joined to the head flange. The latches are pivoted about the pivot supports for selectively engaging and disengaging the latch hooks with the support flange for fixedly joining the head to the shroud or for allowing removal thereof.

Challberg, Roy C. (Livermore, CA); Kobsa, Irvin R. (San Jose, CA)

1994-01-01

209

Disc detector assembly  

SciTech Connect

A miniature, nonevacuated, detector refrigerator assembly for use in infrared imaging systems is described. The assembly incorporates a miniature Joule-Thomson laminar refrigerator which serves as the substrate for the detector subassembly, electrical leads, as well as the primary structural element of the assembly. The detector subassembly is positioned on the cold region of the refrigerator, surrounded by insulating material and capped by an optical window or filter as required. As a result, the detector is cooled while the contact pads used for connection to external devices are at the ambient temperature. A piece of high thermally conductive material may be placed in the vicinity of the detector subassembly so that during operation gases in the chamber surrounding the detector assembly will preferentially condense thereon rather than on the detector subassembly.

Jungkman, D.L.; Coda, R.C.; Nicholson, P.N.

1984-12-18

210

Recuperator Assembly and Procedures.  

National Technical Information Service (NTIS)

A construction of recuperator core segments is provided which insures proper assembly of the components of the recuperator core segment, and of a plurality of recuperator core segments. Each recuperator core segment must be constructed so as to prevent ne...

R. D. McKeirnan Y. Kang

2004-01-01

211

Integrated thruster assembly program  

NASA Technical Reports Server (NTRS)

The program is reported which has provided technology for a long life, high performing, integrated ACPS thruster assembly suitable for use in 100 typical flights of a space shuttle vehicle over a ten year period. The four integrated thruster assemblies (ITA) fabricated consisted of: propellant injector; a capacitive discharge, air gap torch type igniter assembly; fast response igniter and main propellant valves; and a combined regen-dump film cooled chamber. These flightweight 6672 N (1500 lb) thruster assemblies employed GH2/GO2 as propellants at a chamber pressure of 207 N/sq cm (300 psia). Test data were obtained on thrusted performance, thermal and hydraulic characteristics, dynamic response in pulsing, and cycle life. One thruster was fired in excess of 42,000 times.

1973-01-01

212

Rnnotator Assembly Pipeline  

SciTech Connect

Jeff Martin of the DOE Joint Genome Institute discusses a de novo transcriptome assembly pipeline from short RNA-Seq reads on June 3, 2010 at the "Sequencing, Finishing, Analysis in the Future" meeting in Santa Fe, NM

Martin, Jeff [DOE Joint Genome Institute

2010-06-03

213

Microbial Filter Assembly.  

National Technical Information Service (NTIS)

A filter assembly for fluid containing microbial agents comprises a base defining a first broad filter supporting surface for receiving an appropriate microbial filter membrane, and at least one fluid drain disposed therebeneath to conduct the fluid carry...

M. Shepel

1981-01-01

214

Magnetostrictive valve assembly  

NASA Technical Reports Server (NTRS)

A magnetostrictive valve assembly includes a housing that defines a passage with a seat being formed therein. A magnetically-biased and axially-compressed magnetostrictive assembly slidingly fitted in the passage is configured as a hollow and open-ended conduit adapted to support a flow of a fluid therethrough. Current-carrying coil(s) disposed about the passage in the region of the magnetostrictive assembly generate a magnetic field in the passage when current flows through the coil(s). A hollow valve body with side ports is coupled on one end thereof to an axial end of the magnetostrictive assembly. The other end of the valve body is designed to seal with the seat formed in the housing's passage when brought into contact therewith.

Richard, James A. (Inventor)

2008-01-01

215

Station Assembly Animation  

NASA Video Gallery

This animation depicts the assembly of the International Space Station since Nov. 20, 1998, with the delivery of the Zarya module, through May 16, 2011, with the delivery of the EXPRESS Logistics C...

216

Theseus Assembly Sequence #2  

NASA Technical Reports Server (NTRS)

Crew members are seen here assembling the tail of the Theseus prototype research aircraft at NASA's Dryden Flight Research Center, Edwards, California, in May of 1996. The Theseus aircraft, built and operated by Aurora Flight Sciences Corporation, Manassas, Virginia, was a unique aircraft flown at NASA's Dryden Flight Research Center, Edwards, California, under a cooperative agreement between NASA and Aurora. Dryden hosted the Theseus program, providing hangar space and range safety for flight testing. Aurora Flight Sciences was responsible for the actual flight testing, vehicle flight safety, and operation of the aircraft. The Theseus remotely piloted aircraft flew its maiden flight on May 24, 1996, at Dryden. During its sixth flight on November 12, 1996, Theseus experienced an in-flight structural failure that resulted in the loss of the aircraft. As of the beginning of the year 2000, Aurora had not rebuilt the aircraft. Theseus was built for NASA under an innovative, $4.9 million fixed-price contract by Aurora Flight Sciences Corporation and its partners, West Virginia University, Morgantown, West Virginia, and Fairmont State College, Fairmont, West Virginia. The twin-engine, unpiloted vehicle had a 140-foot wingspan, and was constructed largely of composite materials. Powered by two 80-horsepower, turbocharged piston engines that drove twin 9-foot-diameter propellers, Theseus was designed to fly autonomously at high altitudes, with takeoff and landing under the active control of a ground-based pilot in a ground control station 'cockpit.' With the potential ability to carry 700 pounds of science instruments to altitudes above 60,000 feet for durations of greater than 24 hours, Theseus was intended to support research in areas such as stratospheric ozone depletion and the atmospheric effects of future high-speed civil transport aircraft engines. Instruments carried aboard Theseus also would be able to validate satellite-based global environmental change measurements. Dryden's Project Manager was John Del Frate.

1996-01-01

217

Theseus Assembly Sequence #1  

NASA Technical Reports Server (NTRS)

The Theseus prototype research aircraft being assembled at NASA's Dryden Flight Research Center, Edwards, California, in May of 1996. The Theseus aircraft, built and operated by Aurora Flight Sciences Corporation, Manassas, Virginia, was a unique aircraft flown at NASA's Dryden Flight Research Center, Edwards, California, under a cooperative agreement between NASA and Aurora. Dryden hosted the Theseus program, providing hangar space and range safety for flight testing. Aurora Flight Sciences was responsible for the actual flight testing, vehicle flight safety, and operation of the aircraft. The Theseus remotely piloted aircraft flew its maiden flight on May 24, 1996, at Dryden. During its sixth flight on November 12, 1996, Theseus experienced an in-flight structural failure that resulted in the loss of the aircraft. As of the beginning of the year 2000, Aurora had not rebuilt the aircraft. Theseus was built for NASA under an innovative, $4.9 million fixed-price contract by Aurora Flight Sciences Corporation and its partners, West Virginia University, Morgantown, West Virginia, and Fairmont State College, Fairmont, West Virginia. The twin-engine, unpiloted vehicle had a 140-foot wingspan, and was constructed largely of composite materials. Powered by two 80-horsepower, turbocharged piston engines that drove twin 9-foot-diameter propellers, Theseus was designed to fly autonomously at high altitudes, with takeoff and landing under the active control of a ground-based pilot in a ground control station 'cockpit.' With the potential ability to carry 700 pounds of science instruments to altitudes above 60,000 feet for durations of greater than 24 hours, Theseus was intended to support research in areas such as stratospheric ozone depletion and the atmospheric effects of future high-speed civil transport aircraft engines. Instruments carried aboard Theseus also would be able to validate satellite-based global environmental change measurements. Dryden's Project Manager was John Del Frate.

1996-01-01

218

Rover 2 Assembly  

NASA Technical Reports Server (NTRS)

Sept 24, 2002

Rover 2 equipment deck, with solar arrays partially deployed, in JPL's Spacecraft Assembly Facility's cleanroom. The low gain antenna (thick, silver mast in center) and high gain (circular) antennas allow communication with the rover from Earth. The tall, white mast is the rover's Pancam Mast Assembly supporting two stereo camera systems (color and wide angle) and a thermal emission spectrometer for remote mineral identification.

2003-01-01

219

Self Assembly of Colloids  

NASA Astrophysics Data System (ADS)

We are exploring the self assembly of colloidal matter using building blocks with complex shapes and functionalities. Our toolbox includes particles with tunable cavities and protrusions, particles with flexible ball-and-socket joints, colloidal cubes and particles with magnetic patches. Using these building blocks and a variety of interactions, including chemical, steric, magnetic and lock-and-key shape recognition, we aim to develop new assembly schemes to build structures with a reconfigurable structural arrangement.

Sacanna, Stefano

2012-02-01

220

An investigation of Hebbian phase sequences as assembly graphs.  

PubMed

Hebb proposed that synapses between neurons that fire synchronously are strengthened, forming cell assemblies and phase sequences. The former, on a shorter scale, are ensembles of synchronized cells that function transiently as a closed processing system; the latter, on a larger scale, correspond to the sequential activation of cell assemblies able to represent percepts and behaviors. Nowadays, the recording of large neuronal populations allows for the detection of multiple cell assemblies. Within Hebb's theory, the next logical step is the analysis of phase sequences. Here we detected phase sequences as consecutive assembly activation patterns, and then analyzed their graph attributes in relation to behavior. We investigated action potentials recorded from the adult rat hippocampus and neocortex before, during and after novel object exploration (experimental periods). Within assembly graphs, each assembly corresponded to a node, and each edge corresponded to the temporal sequence of consecutive node activations. The sum of all assembly activations was proportional to firing rates, but the activity of individual assemblies was not. Assembly repertoire was stable across experimental periods, suggesting that novel experience does not create new assemblies in the adult rat. Assembly graph attributes, on the other hand, varied significantly across behavioral states and experimental periods, and were separable enough to correctly classify experimental periods (Naïve Bayes classifier; maximum AUROCs ranging from 0.55 to 0.99) and behavioral states (waking, slow wave sleep, and rapid eye movement sleep; maximum AUROCs ranging from 0.64 to 0.98). Our findings agree with Hebb's view that assemblies correspond to primitive building blocks of representation, nearly unchanged in the adult, while phase sequences are labile across behavioral states and change after novel experience. The results are compatible with a role for phase sequences in behavior and cognition. PMID:24782715

Almeida-Filho, Daniel G; Lopes-dos-Santos, Vitor; Vasconcelos, Nivaldo A P; Miranda, José G V; Tort, Adriano B L; Ribeiro, Sidarta

2014-01-01

221

Petri net modelling for robotic assembly and trajectory planning  

Microsoft Academic Search

A new approach to process modelling, task synthesis, motion control and trajectory planning for robotic assembly is presented. Assembly is modelled as a discrete event dynamic system using Petri nets, incorporating both discrete and continuous aspects of the process. A process monitor based on recognizing contact state transitions is presented. A discrete event controller is developed. The controller issues velocity

Brenan J. McCarragher

1994-01-01

222

Simulating control rod and fuel assembly motion using moving meshes  

Microsoft Academic Search

A prerequisite for designing a transient simulation experiment which includes the motion of control and fuel assemblies is the careful verification of a steady state model which computes keff versus assembly insertion distance. Previous studies in nuclear engineering have usually approached the problem of the motion of control rods with the use of nonlinear nodal models. Nodal methods employ special

D. Gilbert; J. E. Roman; Wm. J. Garland; W. F. S. Poehlman

2008-01-01

223

VISUAL SERVOING FOR ROBOTIC ASSEMBLY  

Microsoft Academic Search

Visual feedback has traditionally been used in the assembly process to a very limited extent. With the advent of effective visual servoing techniques, visual feedback can become an integral part of the assembly process by complementing the use of force feedback to accomplish precision assemblies in imprecisely calibrated robotic assembly workcells. In this paper we present some of the issues

Brad Nelson; N. P. Papanikolopoulos; P. K. Khosla

1993-01-01

224

Quality modelling of assembly systems  

Microsoft Academic Search

From the point of view of quality an assembly system can be viewed as consisting of two types of processes, those that create defects (assembly) and those that identify and remove defects (test). Thus in a general simulation model of an assembly system three types of blocks are required, assembly, test, and merge (lumping defects together). This approach was used

J. A. Buzacott; D. W. H. Cheng

1984-01-01

225

Human Assisted Assembly Processes  

SciTech Connect

Automatic assembly sequencing and visualization tools are valuable in determining the best assembly sequences, but without Human Factors and Figure Models (HFFMs) it is difficult to evaluate or visualize human interaction. In industry, accelerating technological advances and shorter market windows have forced companies to turn to an agile manufacturing paradigm. This trend has promoted computerized automation of product design and manufacturing processes, such as automated assembly planning. However, all automated assembly planning software tools assume that the individual components fly into their assembled configuration and generate what appear to be a perfectly valid operations, but in reality the operations cannot physically be carried out by a human. Similarly, human figure modeling algorithms may indicate that assembly operations are not feasible and consequently force design modifications; however, if they had the capability to quickly generate alternative assembly sequences, they might have identified a feasible solution. To solve this problem HFFMs must be integrated with automated assembly planning to allow engineers to verify that assembly operations are possible and to see ways to make the designs even better. Factories will very likely put humans and robots together in cooperative environments to meet the demands for customized products, for purposes including robotic and automated assembly. For robots to work harmoniously within an integrated environment with humans the robots must have cooperative operational skills. For example, in a human only environment, humans may tolerate collisions with one another if they did not cause much pain. This level of tolerance may or may not apply to robot-human environments. Humans expect that robots will be able to operate and navigate in their environments without collisions or interference. The ability to accomplish this is linked to the sensing capabilities available. Current work in the field of cooperative automation has shown the effectiveness of humans and machines directly interacting to perform tasks. To continue to advance this area of robotics, effective means need to be developed to allow natural ways for people to communicate and cooperate with robots just as they do with one another.

CALTON,TERRI L.; PETERS,RALPH R.

2000-01-01

226

Effects of calcination treatment on the morphology, crystallinity, and photoelectric properties of all-solid-state dye-sensitized solar cells assembled by TiO2 nanorod arrays.  

PubMed

TiO2 has been extensively investigated due to its unique photoelectric properties. In this study, oriented single-crystal rutile TiO2 nanorod arrays were synthesized and then calcined at different temperatures in the atmosphere. The morphology and crystalline characterization indicated that the length of TiO2 nanorods increased rapidly and the nanorods became aggregated and fragile after calcination, yet the sintering treatment seemed to have almost no effect on the crystallinity. To obtain the all-solid-state, dye-sensitized solar cells (DSSCs), a newly reported solid inorganic semiconductor, CsSnI2.95F0.05, was employed as the electrolyte, and the Pt deposited on the conductive side of the fluorine-doped tin oxide (FTO) glass substrate was used as the counter-electrode. The effects of the calcination treatment on the photoelectric properties of the solar cells, including external quantum efficiency (EQE), open circuit voltage (V(OC)), short-circuit current (J(SC)), and photoelectric conversion efficiency (?), were investigated under the illumination of a solar simulator. As a result, all of the EQE, V(OC), J(SC), and ? values of the cells first increased and then declined with the increase of calcination temperatures, and the highest ? of 2.81% was obtained by the cell assembled with its TiO2 electrode sintered at 450 °C for 3 h, a value almost 2.5 times that of the non-sintered sample (1.1%). PMID:24071636

Sun, Xianmiao; Sun, Qiong; Li, Yang; Sui, Lina; Dong, Lifeng

2013-11-14

227

Assemblies of Conformal Tanks  

NASA Technical Reports Server (NTRS)

Assemblies of tanks having shapes that conform to each other and/or conform to other proximate objects have been investigated for use in storing fuels and oxidizers in small available spaces in upper stages of spacecraft. Such assemblies might also prove useful in aircraft, automobiles, boats, and other terrestrial vehicles in which space available for tanks is limited. The basic concept of using conformal tanks to maximize the utilization of limited space is not new in itself: for example, conformal tanks are used in some automobiles to store windshield -washer liquid and coolant that overflows from radiators. The novelty of the present development lies in the concept of an assembly of smaller conformal tanks, as distinguished from a single larger conformal tank. In an assembly of smaller tanks, it would be possible to store different liquids in different tanks. Even if the same liquid were stored in all the tanks, the assembly would offer an advantage by reducing the mechanical disturbance caused by sloshing of fuel in a single larger tank: indeed, the requirement to reduce sloshing is critical in some applications. The figure shows a prototype assembly of conformal tanks. Each tank was fabricated by (1) copper plating a wax tank mandrel to form a liner and (2) wrapping and curing layers of graphite/epoxy composite to form a shell supporting the liner. In this case, the conformal tank surfaces are flat ones where they come in contact with the adjacent tanks. A band of fibers around the outside binds the tanks together tightly in the assembly, which has a quasi-toroidal shape. For proper functioning, it would be necessary to maintain equal pressure in all the tanks.

DeLay, Tom

2009-01-01

228

VideoLab: Assembling a Nanowheel  

NSDL National Science Digital Library

Self-assembly is a powerful means of preparing structurally intricate nanomaterials. However, the challenge of forming large, ring-shaped nanomolecules this way is entropically steep. By using a flow reactor system, Miras et al. observed how (3.5 nm in diameter) form with the help of temporary template molecules. These transient templates form, help assemble the ring-shaped molecules around them, and then leave once the wheel is fully formed and reduced to its final electronic state. This animation shows a model of the templating process.

Haralampos N. Miras (The University of Glasgow, Glasgow;WestCHEM, Department of Chemistry); Geoffrey J. T. Cooper (The University of Glasgow, Glasgow;WestCHEM, Department of Chemistry); De-Liang Long (The University of Glasgow, Glasgow;WestCHEM, Department of Chemistry); Hartmut Bogge (Fakultät für Chemie, Universität Bielefeld, Postfach ;); Achim Muller (Fakultät für Chemie, Universität Bielefeld, Postfach ;); Carsten Streb (The University of Glasgow, Glasgow;WestCHEM, Department of Chemistry)

2010-01-01

229

Exploiting lanthanide luminescence in supramolecular assemblies.  

PubMed

Lanthanide ions, due to their unique photo-physical characteristics, have attracted considerable attention in recent years. Their long lifetimes, sharp, well-defined emission bands, and designable environmental sensitivity make them ideal for integration into switchable supramolecular assemblies where emission can report on local conformation and/or coupled energy levels (redox state). The immobilisation of lanthanide containing constructs on interfaces facilitates device integration, the fabrication of advanced sensory and molecular electronic platforms and presents a means by which conformational dynamics within molecular assemblies can be analysed. In this feature article we discuss the current and potential applications for lanthanide luminescence in supramolecular, switchable and surface bound architectures. PMID:24664123

Lehr, Joshua; Beer, Paul D; Faulkner, Stephen; Davis, Jason J

2014-06-01

230

Assembly Test Article (ATA)  

NASA Technical Reports Server (NTRS)

The assembly test article (ATA) consisted of two live loaded redesigned solid rocket motor (RSRM) segments which were assembled and disassembled to simulate the actual flight segment stacking process. The test assembly joint was flight RSRM design, which included the J-joint insulation design and metal capture feature. The ATA test was performed mid-November through 24 December 1987, at Kennedy Space Center (KSC), Florida. The purpose of the test was: certification that vertical RSRM segment mating and separation could be accomplished without any damage; verification and modification of the procedures in the segment stacking/destacking documents; and certification of various GSE to be used for flight assembly and inspection. The RSRM vertical segment assembly/disassembly is possible without any damage to the insulation, metal parts, or seals. The insulation J-joint contact area was very close to the predicted values. Numerous deviations and changes to the planning documents were made to ensure the flight segments are effectively and correctly stacked. Various GSE were also certified for use on flight segments, and are discussed in detail.

Ricks, Glen A.

1988-01-01

231

Photovoltaic self-assembly.  

SciTech Connect

This late-start LDRD was focused on the application of chemical principles of self-assembly on the ordering and placement of photovoltaic cells in a module. The drive for this chemical-based self-assembly stems from the escalating prices in the 'pick-and-place' technology currently used in the MEMS industries as the size of chips decreases. The chemical self-assembly principles are well-known on a molecular scale in other material science systems but to date had not been applied to the assembly of cells in a photovoltaic array or module. We explored several types of chemical-based self-assembly techniques, including gold-thiol interactions, liquid polymer binding, and hydrophobic-hydrophilic interactions designed to array both Si and GaAs PV chips onto a substrate. Additional research was focused on the modification of PV cells in an effort to gain control over the facial directionality of the cells in a solvent-based environment. Despite being a small footprint research project worked on for only a short time, the technical results and scientific accomplishments were significant and could prove to be enabling technology in the disruptive advancement of the microelectronic photovoltaics industry.

Lavin, Judith; Kemp, Richard Alan; Stewart, Constantine A.

2010-10-01

232

International Space Station Carbon Dioxide Removal Assembly Testing  

NASA Technical Reports Server (NTRS)

Performance testing of the International Space Station Carbon Dioxide Removal Assembly flight hardware in the United States Laboratory during 1999 is described. The CDRA exceeded carbon dioxide performance specifications and operated flawlessly. Data from this test is presented.

Knox, James C.

2000-01-01

233

60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS ...  

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

60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS AND FLOATING BARGE IN BACKGROUND, February 16, 1948. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

234

24. Launch Area, Missile Assembly Building, detail of original work ...  

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

24. Launch Area, Missile Assembly Building, detail of original work cabinets VIEW NORTHWEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

235

20. Launch Area, Missile Assembly Building VIEW SOUTHEAST, NORTH AND ...  

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

20. Launch Area, Missile Assembly Building VIEW SOUTHEAST, NORTH AND WEST ELEVATION - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

236

19. Launch Area, general view of Missile Assembly Building and ...  

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

19. Launch Area, general view of Missile Assembly Building and Generator Building VIEW SOUTHWEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

237

22. Launch Area, Missile Assembly Building VIEW SOUTHWEST, EAST AND ...  

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

22. Launch Area, Missile Assembly Building VIEW SOUTHWEST, EAST AND NORTH ELEVATION - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

238

21. Launch Area, Missile Assembly Building VIEW NORTHWEST, SOUTH AND ...  

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

21. Launch Area, Missile Assembly Building VIEW NORTHWEST, SOUTH AND EAST ELEVATION - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

239

Supramolecular assemblies of carotenoids.  

PubMed

Carotenoid self-assemblies were formed by aqueous dilution of ethanolic solutions. The four 3',6'-epimers of capsanthol ((all-E,3R,5'R)-3,3',6'-trihydroxy-beta,kappa-carotene) give rise to right- and left-handed card-pack and head-to-tail types of self-assemblies detected by exciton couplets appearing in the CD spectra. Slow kinetics of formation followed for some of the aggregates indicate the complexity of the process. The exciton signals do not appear from equimolar mixtures of related compounds that produce identical type of aggregates of opposite sense on their own. Transformation of self-assembly may reflect the population of kappa-ring rotamers. PMID:11746813

Zsila, F; Deli, J; Bikádi, Z; Simonyi, M

2001-01-01

240

Power module assembly  

DOEpatents

A power module assembly of the type suitable for deployment in a vehicular power inverter, wherein the power inverter has a grounded chassis, is provided. The power module assembly comprises a conductive base layer electrically coupled to the chassis, an insulating layer disposed on the conductive base layer, a first conductive node disposed on the insulating layer, a second conductive node disposed on the insulating layer, wherein the first and second conductive nodes are electrically isolated from each other. The power module assembly also comprises a first capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the first conductive node, and further comprises a second capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the second conductive node.

Campbell, Jeremy B. (Torrance, CA); Newson, Steve (Redondo Beach, CA)

2011-11-15

241

Solar collector assembly  

SciTech Connect

A plurality of individually adjustable flat mirrors on a common bed of a solar collector assembly reflect the sun's rays into a tubular collector where water is converted to steam for selectively either driving a motor of refrigeration system which cools a cool water tank or directly heating a hot water tank. Coils in the cool water tank supply coolant for room heat exchangers. The exhaust of the motor heats the hot water tank and is then recirculated to produce more steam. Coils in the hot water tank preheat tap water for a hot water heater and other coils therein supply heat for the room heat exchanger. The mirrors are in rows and are individually swivelly mounted and the frame of the collector assembly is pivotally mounted to track the sun. The collector assembly pivots about two divergent axes to track the sun and is counter balanced with respect to both axes.

Daniel, J.H.

1982-08-10

242

Liaison based assembly design  

SciTech Connect

Liaison Based Assembly Design extends the current information infrastructure to support design in terms of kinematic relationships between parts, or liaisons. These liaisons capture information regarding contact, degrees-of-freedom constraints and containment relationships between parts in an assembly. The project involved defining a useful collection of liaison representations, investigating their properties, and providing for maximum use of the data in downstream applications. We tested our ideas by implementing a prototype system involving extensions to Pro/Engineer and the Archimedes assembly planner. With an expanded product model, the design system is more able to capture design intent. When a product update is attempted, increased knowledge availability improves our ability to understand the effect of design changes. Manufacturing and analysis disciplines benefit from having liaison information available, so less time is wasted arguing over incomplete design specifications and our enterprise can be more completely integrated.

Ames, A.; Kholwadwala, D.; Wilson, R.H.

1996-12-01

243

Virion Assembly and Release  

PubMed Central

Hepatitis C virus (HCV) particles exhibit several unusual properties that are not found in other enveloped RNA viruses, most notably their low buoyant density and interaction with serum lipoproteins. With the advent of systems to grow HCV in cell culture, the molecular basis of HCV particle assembly and release can now be addressed. The process of virus assembly involves protein-protein interactions between viral structural and nonstructural proteins and the coordinated action of host factors. This chapter reviews of our current understanding of these interactions and factors.

Lindenbach, Brett D.

2014-01-01

244

Assembling an aesthetic.  

PubMed

Recent research informing and related to the study of three-dimensional scientific models is assembled here in a way that explores an aesthetic, specifically, of touch. I concentrate on the materiality of models, drawing on insights from the history and philosophy of science, design and metaphysics. This article chronicles the ways in which touch, or material interactions, operate in the world of 3D models, and its role in what models mean and do. I end with a call for greater attention to scientific process, described as assembly of and within science, which is revealed by this focus on touch. PMID:23176974

Candela, Emily

2012-12-01

245

Lightweight reflector assembly  

NASA Technical Reports Server (NTRS)

An inexpensive, lightweight reflective assembly member having good optical quality and particularly adaptable to accommodating temperature variations without providing destructive thermal stresses and reflective slope errors is described. The reflective assembly consists of a thin sheet of glass with appropriate reflective coating and a cellular glass block substrate bonded together. The method of fabrication includes abrading the cellular substrate with an abrasive master die to form an appropriate concave surface. An adhesive is applied to the abraded surface and a lamina reflective surface is placed under a uniform pressure to conform the reflective surface onto the desired abraded surface of the substrate.

Argoud, M. J.; Jolley, J.; Walker, W. L. (inventors)

1977-01-01

246

OSIRIS-REx OCAMS detector assembly characterization  

NASA Astrophysics Data System (ADS)

The OSIRIS-REx asteroid sample return mission carries a suite of three cameras referred to as OCAMS. The Space Dynamics Laboratory (SDL) at Utah State University is providing the CCD-based detector assemblies for OCAMS to the Lunar Planetary Lab (LPL) at the University of Arizona. Working with the LPL, SDL has designed the electronics to operate a 1K by 1K frame transfer Teledyne DALSA Multi-Pinned Phase (MPP) CCD. The detector assembly electronics provides the CCD clocking, biasing, and digital interface with the OCAMS payload Command Control Module (CCM). A prototype system was built to verify the functionality of the detector assembly design and to characterize the detector system performance at the intended operating temperatures. The characterization results are described in this paper.

Hancock, J.; Crowther, B.; Whiteley, M.; Burt, R.; Watson, M.; Nelson, J.; Fellows, C.; Rizk, B.; Kinney-Spano, E.; Perry, M.; Hunten, M.

2013-09-01

247

Microcomponent assembly for efficient contacting of fluid  

DOEpatents

The present invention is a fundamental method and apparatus of a microcomponent assembly that overcomes the inherent limitations of state of the art chemical separations. The fundamental element enabling miniaturization is the porous contactor contained within a microcomponent assembly for mass transfer of a working compound from a first medium to a second medium. The porous contactor has a thickness, and a plurality of pores extending through the thickness. The pores are of a geometry cooperating with a boundary tension of one or the other or both of the media thereby preventing migration of one, other or both through the microporous contactor while permitting passage of the working compound. In the microcomponent assembly, the porous contactor is placed between a first laminate such that a first space or first microplenum is formed between the microporous contactor and the first laminate. Additionally, a cover sheet provides a second space or second plenum between the porous contactor and the cover sheet.

Drost, Monte K. (Richland, WA); Wegeng, Robert S. (Richland, WA); Friedrich, Michele (Prosser, WA); Hanna, William T. (Gahanna, OH); Call, Charles J. (Pasco, WA); Kurath, Dean E. (Richland, WA)

2000-01-01

248

Floating assembly of diatom Coscinodiscus sp. microshells.  

PubMed

Diatoms have silica frustules with transparent and delicate micro/nano scale structures, two dimensional pore arrays, and large surface areas. Although, the diatom cells of Coscinodiscus sp. live underwater, we found that their valves can float on water and assemble together. Experiments show that the convex shape and the 40 nm sieve pores of the valves allow them to float on water, and that the buoyancy and the micro-range attractive forces cause the valves to assemble together at the highest point of water. As measured by AFM calibrated glass needles fixed in manipulator, the buoyancy force on a single floating valve may reach up to 10 ?N in water. Turning the valves over, enlarging the sieve pores, reducing the surface tension of water, or vacuum pumping may cause the floating valves to sink. After the water has evaporated, the floating valves remained in their assembled state and formed a monolayer film. The bonded diatom monolayer may be valuable in studies on diatom based optical devices, biosensors, solar cells, and batteries, to better use the optical and adsorption properties of frustules. The floating assembly phenomenon can also be used as a self-assembly method for fabricating monolayer of circular plates. PMID:22387476

Wang, Yu; Pan, Junfeng; Cai, Jun; Zhang, Deyuan

2012-03-30

249

CGAL: computing genome assembly likelihoods  

PubMed Central

Assembly algorithms have been extensively benchmarked using simulated data so that results can be compared to ground truth. However, in de novo assembly, only crude metrics such as contig number and size are typically used to evaluate assembly quality. We present CGAL, a novel likelihood-based approach to assembly assessment in the absence of a ground truth. We show that likelihood is more accurate than other metrics currently used for evaluating assemblies, and describe its application to the optimization and comparison of assembly algorithms. Our methods are implemented in software that is freely available at http://bio.math.berkeley.edu/cgal/.

2013-01-01

250

Corner-cutting mining assembly  

DOEpatents

This invention resulted from a contract with the United States Department of Energy and relates to a mining tool. More particularly, the invention relates to an assembly capable of drilling a hole having a square cross-sectional shape with radiused corners. In mining operations in which conventional auger-type drills are used to form a series of parallel, cylindrical holes in a coal seam, a large amount of coal remains in place in the seam because the shape of the holes leaves thick webs between the holes. A higher percentage of coal can be mined from a seam by a means capable of drilling holes having a substantially square cross section. It is an object of this invention to provide an improved mining apparatus by means of which the amount of coal recovered from a seam deposit can be increased. Another object of the invention is to provide a drilling assembly which cuts corners in a hole having a circular cross section. These objects and other advantages are attained by a preferred embodiment of the invention.

Bradley, J.A.

1981-07-01

251

Walking boot assembly  

NASA Technical Reports Server (NTRS)

A walking boot assembly particularly suited for use with a positively pressurized spacesuit is presented. A bootie adapted to be secured to the foot of a wearer, an hermetically sealed boot for receiving the bootie having a walking sole, an inner sole, and an upper portion adapted to be attached to an ankle joint of a spacesuit, are also described.

Vykukal, H. C.; Chambers, A. B.; Stjohn, R. H. (inventors)

1977-01-01

252

Rotary shaft sealing assembly  

DOEpatents

A rotary shaft sealing assembly in which a first fluid is partitioned from a second fluid in a housing assembly having a rotary shaft located at least partially within. In one embodiment a lip seal is lubricated and flushed with a pressure-generating seal ring preferably having an angled diverting feature. The pressure-generating seal ring and a hydrodynamic seal may be used to define a lubricant-filled region with each of the seals having hydrodynamic inlets facing the lubricant-filled region. Another aspect of the sealing assembly is having a seal to contain pressurized lubricant while withstanding high rotary speeds. Another rotary shaft sealing assembly embodiment includes a lubricant supply providing a lubricant at an elevated pressure to a region between a lip seal and a hydrodynamic seal with a flow control regulating the flow of lubricant past the lip seal. The hydrodynamic seal may include an energizer element having a modulus of elasticity greater than the modulus of elasticity of a sealing lip of the hydrodynamic seal.

Dietle, Lannie L. (Houston, TX); Schroeder, John E. (Richmond, TX); Kalsi, Manmohan S. (Houston, TX); Alvarez, Patricio D. (Richmond, TX)

2010-09-21

253

Segmented stator assembly  

DOEpatents

An electric machine and stator assembly are provided that include a continuous stator portion having stator teeth, and a tooth tip portion including tooth tips corresponding to the stator teeth of the continuous stator portion, respectively. The tooth tip portion is mounted onto the continuous stator portion.

Lokhandwalla, Murtuza; Alexander, James Pellegrino; El-Refaie, Ayman Mohamed Fawzi; Shah, Manoj Ramprasad; Quirion, Owen Scott

2013-04-02

254

Modeling Protein Self Assembly  

ERIC Educational Resources Information Center

Understanding the structure and function of proteins is an important part of the standards-based science curriculum. Proteins serve vital roles within the cell and malfunctions in protein self assembly are implicated in degenerative diseases. Experience indicates that this topic is a difficult one for many students. We have found that the concept…

Baker, William P.; Jones, Carleton Buck; Hull, Elizabeth

2004-01-01

255

Normal Belt Capstan Assembly.  

National Technical Information Service (NTIS)

A normal belt capstan assembly for arrays towed by vessels includes a drive wheel mounted on the vessel and adapted to deploy and discharge an array. The drive wheel has a continuous groove throughout an outer edge thereof with opposed rims on either side...

V. J. Marolda

2006-01-01

256

Spool assembly support analysis  

SciTech Connect

This document provides the wind/seismic analysis and evaluation for the pump pit spool assemblies. Hand calculations were used for the analysis. UBC, AISC, and load factors were used in this evaluation. The results show that the actual loads are under the allowable loads and all requirements are met.

Norman, B.F.

1994-10-07

257

Beyond the Assembly Line.  

ERIC Educational Resources Information Center

Describes how Hughes Aircraft trainers followed four steps in meeting the challenges of a flexible manufacturing environment: needs assessment, design strategy, pilot evaluation, and follow-through. Within this environment, 50 self-paced training products were developed for one of the company's wire and back plane harness assembly departments. (CT)

Weitz, Rebecca; Guild, Todd

1985-01-01

258

Nuclear fuel assembly spacer  

SciTech Connect

In a fuel assembly for a nuclear reactor a fuel element spacer formed of an array of laterally positioned cojoined tubular ferrules each providing a passage for one of the fuel elements, the elements being laterally supported in the ferrules between slender spring members and laterally oriented rigid stops.

Matzner, B.; Curulla, M. V.; Horn, V. M.; Price, J. F.

1985-04-02

259

Uniform Test Assembly  

ERIC Educational Resources Information Center

In educational practice, a test assembly problem is formulated as a system of inequalities induced by test specifications. Each solution to the system is a test, represented by a 0-1 vector, where each element corresponds to an item included (1) or not included (0) into the test. Therefore, the size of a 0-1 vector equals the number of items "n"…

Belov, Dmitry I.

2008-01-01

260

Admission mixing duct assembly  

NASA Technical Reports Server (NTRS)

A variable cycle jet engine is provided with a mixing duct assembly which mixes core engine exhaust gas with bypass air when the engine is operating in a turbofan mode and which blocks flow from the core engine and isolates the core engine from the bypass flow when the engine is operating as a ramjet.

Orlando, Robert J. (Inventor); Dunbar, Lawrence W. (Inventor)

1995-01-01

261

Temperature Sensing Assembly.  

National Technical Information Service (NTIS)

A temperature sensing assembly which continuously senses the temperature of one constituent stream, of a plurality of constituent streams, of a flow of a gaseous medium; and, as a result of such sensing, generates pneumatic servo-pressure to drive air val...

R. L. Williams

1980-01-01

262

Corium protection assembly  

DOEpatents

A corium protection assembly includes a perforated base grid disposed below a pressure vessel containing a nuclear reactor core and spaced vertically above a containment vessel floor to define a sump therebetween. A plurality of layers of protective blocks are disposed on the grid for protecting the containment vessel floor from the corium.

Gou, Perng-Fei (Saratoga, CA); Townsend, Harold E. (Campbell, CA); Barbanti, Giancarlo (Sirtori, IT)

1994-01-01

263

Dump valve assembly  

DOEpatents

A dump valve assembly comprising a body having a bore defined by a tapered wall and a truncated spherical valve member adapted to seat along a spherical surface portion thereof against said tapered wall. Means are provided for pivoting said valve member between a closed position engagable with said tapered wall and an open position disengaged therefrom.

Owen, T.J.

1984-01-01

264

Fastener and connection assembly  

US Patent & Trademark Office Database

A fastener has an integral closure. The fastener maintains the relative position of concentrically nested or telescopically related inner and outer tubes. The closure occludes the inner tube. The fastener can be used for assembling children's products such as play-yards, strollers, swings, and other types of furniture, transports, and accessories.

2002-02-05

265

LOCAS - A Low Coverage Assembly Tool for Resequencing Projects  

PubMed Central

Motivation Next Generation Sequencing (NGS) is a frequently applied approach to detect sequence variations between highly related genomes. Recent large-scale re-sequencing studies as the Human 1000 Genomes Project utilize NGS data of low coverage to afford sequencing of hundreds of individuals. Here, SNPs and micro-indels can be detected by applying an alignment-consensus approach. However, computational methods capable of discovering other variations such as novel insertions or highly diverged sequence from low coverage NGS data are still lacking. Results We present LOCAS, a new NGS assembler particularly designed for low coverage assembly of eukaryotic genomes using a mismatch sensitive overlap-layout-consensus approach. LOCAS assembles homologous regions in a homology-guided manner while it performs de novo assemblies of insertions and highly polymorphic target regions subsequently to an alignment-consensus approach. LOCAS has been evaluated in homology-guided assembly scenarios with low sequence coverage of Arabidopsis thaliana strains sequenced as part of the Arabidopsis 1001 Genomes Project. While assembling the same amount of long insertions as state-of-the-art NGS assemblers, LOCAS showed best results regarding contig size, error rate and runtime. Conclusion LOCAS produces excellent results for homology-guided assembly of eukaryotic genomes with short reads and low sequencing depth, and therefore appears to be the assembly tool of choice for the detection of novel sequence variations in this scenario.

Klein, Juliane D.; Ossowski, Stephan; Schneeberger, Korbinian; Weigel, Detlef; Huson, Daniel H.

2011-01-01

266

Space assembly fixtures and aids  

NASA Technical Reports Server (NTRS)

Concepts and requirements for assembly fixtures and aids necessary for the assembly and maintenance of spare platforms were studied. Emphasis was placed on erectable and deployable type structures with the shuttle orbiter as the assembly base. Both single and multiple orbiter flight cases for the platform assembly were considered. Applicable space platform assembly studies were reviewed to provide a data base for establishing the assembly fixture and aids design requirements, assembly constraints, and the development of representative design concepts. Conclusions indicated that fixture requirements will vary with platform size. Larger platforms will require translation relative to the orbiter RMS working volume. The installation of platform payloads and subsystems (e.g., utility distribution) must also be considered in the specification of assembly fixtures and aids.

Bloom, K. A.; Lillenas, A. N.

1980-01-01

267

School Assemblies: The Lost Art.  

ERIC Educational Resources Information Center

Guidelines and suggestions are offered for successful school assemblies. The school assembly should be a positive event; an occasion for developing unity, group loyalty, and desirable audience habits. (Author/MLF)

Beach, Daniel R.

1979-01-01

268

Self-assembled plasmonic nanostructures.  

PubMed

Self-assembly of plasmonic nanoparticles offers a labour- and cost-efficient strategy for the expansion of the library of plasmonic nanostructures with highly tunable, coupled optical properties. This review covers recent advances in solution-based self-assembly of plasmonic nanoparticles, modelling of the self-assembly process and of the optical properties of the resulting nanostructures, and potential applications of self-assembled plasmonic nanostructures. PMID:24599020

Klinkova, Anna; Choueiri, Rachelle M; Kumacheva, Eugenia

2014-06-01

269

ASSEMBLY TRANSFER SYSTEM DESCRIPTION DOCUMENT  

Microsoft Academic Search

The Assembly Transfer System (ATS) receives, cools, and opens rail and truck transportation casks from the Carrier\\/Cask Handling System (CCHS). The system unloads transportation casks consisting of bare Spent Nuclear Fuel (SNF) assemblies, single element canisters, and Dual Purpose Canisters (DPCs). For casks containing DPCs, the system opens the DPCs and unloads the SNF. The system stages the assemblies, transfer

B. Gorpani

2000-01-01

270

HIV1 assembly in macrophages  

Microsoft Academic Search

The molecular mechanisms involved in the assembly of newly synthesized Human Immunodeficiency Virus (HIV) particles are poorly understood. Most of the work on HIV-1 assembly has been performed in T cells in which viral particle budding and assembly take place at the plasma membrane. In contrast, few studies have been performed on macrophages, the other major target of HIV-1. Infected

Philippe Benaroch; Elisabeth Billard; Raphaël Gaudin; Michael Schindler; Mabel Jouve

2010-01-01

271

Molded Bobbin Head Coil Assembly.  

National Technical Information Service (NTIS)

The patent application relates to the head coil assembly for a missile. Positioned within the interior of the head coil assembly is an optical gyroscope, such as disclosed in the co-pending application. The head coil assembly contains the reactor coils, p...

R. M. Van Zyl

1974-01-01

272

Fuel nozzle assembly  

DOEpatents

A fuel nozzle assembly is provided. The assembly includes an outer nozzle body having a first end and a second end and at least one inner nozzle tube having a first end and a second end. One of the nozzle body or nozzle tube includes a fuel plenum and a fuel passage extending therefrom, while the other of the nozzle body or nozzle tube includes a fuel injection hole slidably aligned with the fuel passage to form a fuel flow path therebetween at an interface between the body and the tube. The nozzle body and the nozzle tube are fixed against relative movement at the first ends of the nozzle body and nozzle tube, enabling the fuel flow path to close at the interface due to thermal growth after a flame enters the nozzle tube.

Johnson, Thomas Edward (Greer, SC); Ziminsky, Willy Steve (Simpsonville, SC); Lacey, Benjamin Paul (Greer, SC); York, William David (Greer, SC); Stevenson, Christian Xavier (Inman, SC)

2011-08-30

273

Low inductance busbar assembly  

DOEpatents

A busbar assembly for electrically coupling first and second busbars to first and second contacts, respectively, on a power module is provided. The assembly comprises a first terminal integrally formed with the first busbar, a second terminal integrally formed with the second busbar and overlapping the first terminal, a first bridge electrode having a first tab electrically coupled to the first terminal and overlapping the first and second terminals, and a second tab electrically coupled to the first contact, a second bridge electrode having a third tab electrically coupled to the second terminal, and overlapping the first and second terminals and the first tab, and a fourth tab electrically coupled to the second contact, and a fastener configured to couple the first tab to the first terminal, and the third tab to the second terminal.

Holbrook, Meghan Ann (Manhattan Beach, CA)

2010-09-21

274

Ingestion resistant seal assembly  

DOEpatents

A seal assembly limits gas leakage from a hot gas path to one or more disc cavities in a gas turbine engine. The seal assembly includes a seal apparatus associated with a blade structure including a row of airfoils. The seal apparatus includes an annular inner shroud associated with adjacent stationary components, a wing member, and a first wing flange. The wing member extends axially from the blade structure toward the annular inner shroud. The first wing flange extends radially outwardly from the wing member toward the annular inner shroud. A plurality of regions including one or more recirculation zones are defined between the blade structure and the annular inner shroud that recirculate working gas therein back toward the hot gas path.

Little, David A. (Chuluota, FL)

2011-12-13

275

Turbine seal assembly  

DOEpatents

A seal assembly that limits gas leakage from a hot gas path to one or more disc cavities in a turbine engine. The seal assembly includes a seal apparatus that limits gas leakage from the hot gas path to a respective one of the disc cavities. The seal apparatus comprises a plurality of blade members rotatable with a blade structure. The blade members are associated with the blade structure and extend toward adjacent stationary components. Each blade member includes a leading edge and a trailing edge, the leading edge of each blade member being located circumferentially in front of the blade member's corresponding trailing edge in a direction of rotation of the turbine rotor. The blade members are arranged such that a space having a component in a circumferential direction is defined between adjacent circumferentially spaced blade members.

Little, David A.

2013-04-16

276

Vacuum breaker valve assembly  

DOEpatents

Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening.

Thompson, Jeffrey L. (San Jose, CA) [San Jose, CA; Upton, Hubert Allen (Morgan Hill, CA) [Morgan Hill, CA

1999-04-27

277

Vacuum breaker valve assembly  

DOEpatents

Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening. 1 fig.

Thompson, J.L.; Upton, H.A.

1999-04-27

278

Ribosome assembly in eukaryotes.  

PubMed

Ribosome synthesis is a highly complex and coordinated process that occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells. Based on the protein composition of several ribosomal subunit precursors recently characterized in yeast, a total of more than 170 factors are predicted to participate in ribosome biogenesis and the list is still growing. So far the majority of ribosomal factors have been implicated in RNA maturation (nucleotide modification and processing). Recent advances gave insight into the process of ribosome export and assembly. Proteomic approaches have provided the first indications for a ribosome assembly pathway in eukaryotes and confirmed the dynamic character of the whole process. PMID:12957375

Fromont-Racine, Micheline; Senger, Bruno; Saveanu, Cosmin; Fasiolo, Franco

2003-08-14

279

Mechanical seal assembly  

DOEpatents

An improved mechanical seal assembly is provided for sealing rotating shafts with respect to their shaft housings, wherein the rotating shafts are subject to substantial axial vibrations. The mechanical seal assembly generally includes a rotating sealing ring fixed to the shaft, a non-rotating sealing ring adjacent to and in close contact with the rotating sealing ring for forming an annular seal about the shaft, and a mechanical diode element that applies a biasing force to the non-rotating sealing ring by means of hemispherical joint. The alignment of the mechanical diode with respect to the sealing rings is maintained by a series of linear bearings positioned axially along a desired length of the mechanical diode. Alternative embodiments include mechanical or hydraulic amplification components for amplifying axial displacement of the non-rotating sealing ring and transfering it to the mechanical diode.

Kotlyar, Oleg M. (Salt Lake City, UT)

2002-01-01

280

Mechanical seal assembly  

DOEpatents

An improved mechanical seal assembly is provided for sealing rotating shafts with respect to their shaft housings, wherein the rotating shafts are subject to substantial axial vibrations. The mechanical seal assembly generally includes a rotating sealing ring fixed to the shaft, a non-rotating sealing ring adjacent to and in close contact with the rotating sealing ring for forming an annular seal about the shaft, and a mechanical diode element that applies a biasing force to the non-rotating sealing ring by means of hemispherical joint. The alignment of the mechanical diode with respect to the sealing rings is maintained by a series of linear bearings positioned axially along a desired length of the mechanical diode. Alternative embodiments include mechanical or hydraulic amplification components for amplifying axial displacement of the non-rotating sealing ring and transferring it to the mechanical diode.

Kotlyar, Oleg M. (Salt Lake City, UT)

2001-01-01

281

Percussion igniter assembly  

SciTech Connect

An igniter assembly is described for initiating burning of a combustible material, said igniter assembly comprising: an ignitable material for initiating burning of the combustible material when said ignitable material is ignited; and plurality of primer elements which are actuatable to ignite said ignitable material in response to the application of force against said primer elements; an impact member which is movable to apply force against said primer elements to actuate said primer elements, said impact member having an annular surface for applying force to each of said primer elements simultaneously; a base structure for supporting said primer elements, said base structure having a base surface means including a recess into which said annular surface of said impact member is movable; and said recess having first portions and second portions, said first portions of said recess being arranged in a circular array and containing said primer elements, said second portions of said recess having arcuate shapes and extending circumferentially between said first portions.

Coultas, T.J.

1993-07-13

282

Hearing Aid Assembly  

NASA Technical Reports Server (NTRS)

Progress in hearing aids has come a long way. Yet despite such progress hearing aids are not the perfect answer to many hearing problems. Some adult ears cannot accommodate tightly fitting hearing aids. Mouth movements such as chewing, talking, and athletic or other active endeavors also lead to loosely fitting ear molds. It is well accepted that loosely fitting hearing aids are the cause of feedback noise. Since feedback noise is the most common complaint of hearing aid wearers it has been the subject of various patents. Herein a hearing aid assembly is provided eliminating feedback noise. The assembly includes the combination of a hearing aid with a headset developed to constrict feedback noise.

Grugel, Richard N. (Inventor)

2002-01-01

283

Infrared floodlight assembly  

DOEpatents

An infrared floodlight assembly (10) including a cast aluminum outer housing (11) defining a central chamber (15) therein. A floodlight (14), having a tungsten halogen lamp as the light source, is spacedly positioned within a heat conducting member (43) within chamber (15) such that the floodlight is securedly positioned in an aligned manner relative to the assembly's filter (35) and lens (12) components. The invention also includes venting means (51) to allow air passage between the interior of the member (43) and the adjacent chamber (15), as well as engagement means (85) for engaging a rear surface of the floodlight (14) to retain it firmly against an internal flange of the member (43). A reflector (61), capable of being compressed to allow insertion or removal, is located within the heat conducting member's interior between the floodlight (14) and filter (35) to reflect infrared radiation toward the filter (35) and spaced lens (12).

Wierzbicki, Julian J. (Peabody, MA); Chakrabarti, Kirti B. (Danvers, MA)

1987-09-22

284

Printed Wiring Assembly and Interconnection Reliability.  

National Technical Information Service (NTIS)

This report presents reliability prediction models for printed wiring assemblies, solderless wrap assemblies, wrapped and soldered assemblies, and discrete wiring assemblies w/electroless deposited PTH for inclusion in MIL-HDBK-217. Collected field failur...

D. W. Coit

1981-01-01

285

Packerless well completion assembly  

SciTech Connect

A subsurface well bore comtletion assembly without conventional inflatable or cup packer elements. The completion is effected by cementing a member having an internal sealing surface in place within the well then running tubing string terminating with a sealing adapter having matching sealing face into the cemented member and sealing said well by pressing the surface and face together under the weight of the tubing string.

Hutchison, S.O.

1983-05-31

286

Magnetic control assembly reports  

NASA Technical Reports Server (NTRS)

Results are summarized of the qualification level vibration tests performed on the magnet control assembly (MCA) for Nimbus and ERTS satellites. The MCA electronics and probe units have demonstrated the capability to survive qualification sinusoidal and random vibration levels. The functional testing indicated normal operation of the units after each axis of vibration. Visual inspection indicated no evidence of degradation. Post vibration acceptance testing verified normal operation of the MCA.

Stickler, A. C.

1972-01-01

287

HSPES membrane electrode assembly  

NASA Technical Reports Server (NTRS)

An improved fuel cell electrode, as well as fuel cells and membrane electrode assemblies that include such an electrode, in which the electrode includes a backing layer having a sintered layer thereon, and a non-sintered free-catalyst layer. The invention also features a method of forming the electrode by sintering a backing material with a catalyst material and then applying a free-catalyst layer.

Kindler, Andrew (Inventor); Yen, Shiao-Ping (Inventor)

2000-01-01

288

CMS Solenoid Assembly  

Microsoft Academic Search

CMS (Compact Muon Solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with a 6 m diameter by 12.5 m long free bore, enclosed inside a 10,000-ton return yoke. The assembly of the solenoid on CERN site starts with the building

B. Levesy; P. Bredy; D. Campi; P. Fabbricatore; A. Gaddi; H. Gerwig; M. Greco; A. Herve; F. Kircher; Y. Pabot; P. Petiot; J. Y. Rousse; L. Scola; C. D'Urzo; L. Veillet

2006-01-01

289

Pull rod assembly  

DOEpatents

A pull rod assembly comprising a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring, said piston device being mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

Cioletti, O.C.

1988-04-21

290

Nuclear fuel assembly spacer  

SciTech Connect

A spacer for use in a fuel assembly of a nuclear reactor having thin, full-height divider members, slender spring members and laterally oriented rigid stops and wherein the total amount of spacer material, the amount of high neutron cross section material, the projected area of the spacer structure and changes in cross section area of the spacer structure are minimized whereby neutron absorption by the spacer and coolant flow resistance through the spacer are minimized.

Curulla, M. V.; Brayman, K. W.; Matzner, B.; Price, T. F.; Qurnell, F. D.

1985-10-01

291

Continuously flushed thermocouple assembly  

SciTech Connect

This patent describes a thermocouple assembly in combination with a melting furnace for containing a body of molten glass, comprising: a thermocouple element having a junction; a first sleeve; a second sleeve; means for sealing the second end of the second sleeve to the first sleeve to provide a second annular space having a closed end adjacent the second end of the second sleeve and an open portion at the first end of the second sleeve to provide the thermocouple assembly; means for securing the thermocouple assembly in the hole with the closed first end of the first sleeve extending into the molten glass and the second end of the second sleeve at or extending beyond outer surface of the wall having the hole; means for sealing the first end of the second sleeve and space between the first end of the second sleeve and adjacent wall portion of the hole to provide a sealed second annular space; and means for moving a corrosion-inhibiting gas into, through, and out of at least one of the annular spaces to flush the at least one of the annular spaces.

Krumwiede, J.F.; Sims, R.M.

1988-05-31

292

Saddle clamp assembly  

NASA Technical Reports Server (NTRS)

A saddle clamp assembly is presented. The assembly is comprised of a hollow cylindrical body centered about a longitudinal axis and being diametrically split into semicircular top and bottom sections. Each section has a pair of connection flanges, at opposite ends, that project radially outward. A pair of bolts are retained on the top section flanges and are threadable into nuts retained on the bottom section flanges. A base member is anchored to a central underside portion of the bottom clamp body section and has a pair of connection tabs positioned beneath the bottom clamp body section connection flanges on opposite sides of the clamp axis. A pair of bolts are retained on the base member connection tabs and are threadable into a pair of nuts retainable on a support structure. The connection tab and connection flanges on each side of the clamp body are axially offset in a manner permitting downward installation/removable tool access to the lower bolts past the connection flanges. An elongated retention tether is used to connect the top clamp body section to the balance of the clamp assembly. This prevents loss of the top clamp body section when it is removed from the bottom clamp body section.

Belrose, Charles R. (inventor)

1994-01-01

293

OH Module Assembly Stand  

SciTech Connect

There is an OR module assembly stand in use at IB4. This design has been approved by safety, as presented by Mike Foley, and has been successfully used. Another one is needed at the D-zero assembly building, but some modifications need to be made. This report will show that the new modified design is at least as strong, if not stronger, than the older IB4 design in every aspect. Since the weight distribution of the OR modules on the sling is indeterminate, this report compares three cases of support for the entire assembly: the lowest two beams only, the lowest four beams only, and all six beams. In each of these cases, the new design is stronger than the old design in maximum allowable weight. The ability of the the cradle to support the weight is also shown. For all of the failure conditions except for two, the cradle is stronger than the beams that it supports. In the two excepted situations, the calculated limit of the cradle is less than the beams it supports. This is because no credit is taken for the sling and strongback, which in reality will relieve much of the horizontal load.

Bolan, P.J.; /Fermilab

1990-10-16

294

Retractable Visual Indicator Assembly  

NASA Technical Reports Server (NTRS)

A retractable indicator assembly may be mounted on a container which transmits air through the container and removes deleterious gases with an activated charcoal medium in the container. The assembly includes: an elongate indicator housing has a chamber therein; a male adaptor with an external threads is used for sealing engagement with the container; a plug located at the upper end of the housing; a housing that includes a transparent wall portion for viewing at least a portion of the chamber; a litmus indicator, moveable by a retractable rod from a retracted position within the container to an extended position within the chamber of the housing; and an outer housing that is secured to the upper end of the rod, and protects the indicator housing while the litmus indicator is in its normally retracted position. The assembly may be manually manipulated between its extended position wherein the litmus indicator may be viewed through the transparent wall of the indicator housing, and a retracted position wherein the outer housing encloses the indicator housing and engages the exterior of the container.

Hackler, George R. (Inventor); Gamboa, Ronald J. (Inventor); Dominquez, Victor (Inventor)

1998-01-01

295

Self assembling phenylene vinylene materials and devices  

NASA Astrophysics Data System (ADS)

A new class of self assembling rodcoil molecules was recently synthesized and their solid state structure was rigorously characterized. These molecules have a triblock architecture with a rigid rod molecular compound coupled to a diblock coil composed of an oligomeric flexible spacer and a bulky coil. The molecular structure has integrated photonic properties resulting from phenylene vinylene segments in the rigid backbone of the rod segment. It has been found that these molecules aggregate spontaneously when cast from solution into discrete objects with dimensions on the order of a few nanometers. The driving force for this aggregation is the crystallization of rod segments. To probe structure-property relationships in these materials, piezoelectric measurements were carried out in films and spontaneous piezoelectric activity was demonstrated without prior poling procedures. Upon poling the net polarization was enhanced and piezoelectric activities equal to that of quartz were observed. By applying both positive and negative fields a hysteresis was observed suggesting that these materials exhibit ferroelectric character. Through novel synthesis a structure was synthesized in the author's laboratory modeled after the triblock but targeting a diode-like aggregate upon self assembly. The molecules contained emissive phenylene vinylene segments in the rod block and hole transporting triphenylamine groups in the coil. Through subsequent characterization it was shown that the formation of nanoaggregates is indeed governed by the molecular architecture rather than the specific chemical functions of the three molecular segments. Inspired by these supramolecular diodes, self assembled organic light emitting diodes were fabricated based on a different self assembly approach. Prior to annealing, electron microscopy clearly showed kinetically trapped phase separated films. However after annealing a bilayer arrangement was observed with the hole conducting oligomer on the hole injecting electrode and the emissive phenylene vinylene dendron segregated to the electron injecting metal, the desired self assembled state. (Abstract shortened by UMI.)

Pralle, Martin Ulrich

296

Self-assembly from milli- to nanoscales: methods and applications  

PubMed Central

The design and fabrication techniques for microelectromechanical systems (MEMS) and nanodevices are progressing rapidly. However, due to material and process flow incompatibilities in the fabrication of sensors, actuators and electronic circuitry, a final packaging step is often necessary to integrate all components of a heterogeneous microsystem on a common substrate. Robotic pick-and-place, although accurate and reliable at larger scales, is a serial process that downscales unfavorably due to stiction problems, fragility and sheer number of components. Self-assembly, on the other hand, is parallel and can be used for device sizes ranging from millimeters to nanometers. In this review, the state-of-the-art in methods and applications for self-assembly is reviewed. Methods for assembling three-dimensional (3D) MEMS structures out of two-dimensional (2D) ones are described. The use of capillary forces for folding 2D plates into 3D structures, as well as assembling parts onto a common substrate or aggregating parts to each other into 2D or 3D structures, is discussed. Shape matching and guided assembly by magnetic forces and electric fields are also reviewed. Finally, colloidal self-assembly and DNA-based self-assembly, mainly used at the nanoscale, are surveyed, and aspects of theoretical modeling of stochastic assembly processes are discussed.

Mastrangeli, M; Abbasi, S; Varel, C; Van Hoof, C; Celis, J-P; Bohringer, K F

2009-01-01

297

Accurate viral population assembly from ultra-deep sequencing data  

PubMed Central

Motivation: Next-generation sequencing technologies sequence viruses with ultra-deep coverage, thus promising to revolutionize our understanding of the underlying diversity of viral populations. While the sequencing coverage is high enough that even rare viral variants are sequenced, the presence of sequencing errors makes it difficult to distinguish between rare variants and sequencing errors. Results: In this article, we present a method to overcome the limitations of sequencing technologies and assemble a diverse viral population that allows for the detection of previously undiscovered rare variants. The proposed method consists of a high-fidelity sequencing protocol and an accurate viral population assembly method, referred to as Viral Genome Assembler (VGA). The proposed protocol is able to eliminate sequencing errors by using individual barcodes attached to the sequencing fragments. Highly accurate data in combination with deep coverage allow VGA to assemble rare variants. VGA uses an expectation–maximization algorithm to estimate abundances of the assembled viral variants in the population. Results on both synthetic and real datasets show that our method is able to accurately assemble an HIV viral population and detect rare variants previously undetectable due to sequencing errors. VGA outperforms state-of-the-art methods for genome-wide viral assembly. Furthermore, our method is the first viral assembly method that scales to millions of sequencing reads. Availability: Our tool VGA is freely available at http://genetics.cs.ucla.edu/vga/ Contact: serghei@cs.ucla.edu; eeskin@cs.ucla.edu

Mangul, Serghei; Eskin, Eleazar

2014-01-01

298

Macromolecular symmetric assembly prediction using swarm intelligence dynamic modeling.  

PubMed

Proteins often assemble in multimeric complexes to perform a specific biologic function. However, trapping these high-order conformations is difficult experimentally. Therefore, predicting how proteins assemble using in silico techniques can be of great help. The size of the associated conformational space and the fact that proteins are intrinsically flexible structures make this optimization problem extremely challenging. Nonetheless, known experimental spatial restraints can guide the search process, contributing to model biologically relevant states. We present here a swarm intelligence optimization protocol able to predict the arrangement of protein symmetric assemblies by exploiting a limited amount of experimental restraints and steric interactions. Importantly, within this scheme the native flexibility of each protein subunit is taken into account as extracted from molecular dynamics (MD) simulations. We show that this is a key ingredient for the prediction of biologically functional assemblies when, upon oligomerization, subunits explore activated states undergoing significant conformational changes. PMID:23810695

Degiacomi, Matteo T; Dal Peraro, Matteo

2013-07-01

299

Assembly kinetics of nanocrystals via peptide hybridization.  

PubMed

The assembly kinetics of colloidal semiconductor quantum dots (QDs) on solid inorganic surfaces is of fundamental importance for implementation of their solid-state devices. Herein an inorganic binding peptide, silica binding QBP1, was utilized for the self-assembly of nanocrystal quantum dots on silica surface as a smart molecular linker. The QD binding kinetics was studied comparatively in three different cases: first, QD adsorption with no functionalization of substrate or QD surface; second, QD adsorption on QBP1-modified surface; and, finally, adsorption of QBP1-functionalized QD on silica surface. The surface modification of QDs with QBP1 enabled 79.3-fold enhancement in QD binding affinity, while modification of a silica surface with QBP1 led to only 3.3-fold enhancement. The fluorescence microscopy images also supported a coherent assembly with correspondingly increased binding affinity. Decoration of QDs with inorganic peptides was shown to increase the amount of surface-bound QDs dramatically compared to the conventional methods. These results offer new opportunities for the assembly of QDs on solid surfaces for future device applications. PMID:21410195

Seker, Urartu Ozgur Safak; Zengin, Gulis; Tamerler, Candan; Sarikaya, Mehmet; Demir, Hilmi Volkan

2011-04-19

300

Multispecies population dynamics of prebiotic compositional assemblies.  

PubMed

Present life portrays a two-tier phenomenology: molecules compose supramolecular structures, such as cells or organisms, which in turn portray population behaviors, including selection, evolution and ecological dynamics. Prebiotic models have often focused on evolution in populations of self-replicating molecules, without explicitly invoking the intermediate molecular-to-supramolecular transition. Here, we explore a prebiotic model that allows one to relate parameters of chemical interaction networks within molecular assemblies to emergent population dynamics. We use the graded autocatalysis replication domain (GARD) model, which simulates the network dynamics within amphiphile-containing molecular assemblies, and exhibits quasi-stationary compositional states termed compotype species. These grow by catalyzed accretion, divide and propagate their compositional information to progeny in a replication-like manner. The model allows us to ask how molecular network parameters influence assembly evolution and population dynamics parameters. In 1000 computer simulations, each embodying different parameter set of the global chemical interaction network parameters, we observed a wide range of behaviors. These were analyzed by a multi species logistic model often used for analyzing population ecology (r-K or Lotka-Volterra competition model). We found that compotypes with a larger intrinsic molecular repertoire show a higher intrinsic growth (r) and lower carrying capacity (K), as well as lower replication fidelity. This supports a prebiotic scenario initiated by fast-replicating assemblies with a high molecular diversity, evolving into more faithful replicators with narrower molecular repertoires. PMID:24831416

Markovitch, Omer; Lancet, Doron

2014-09-21

301

Calixarene-encapsulated nanoparticles: self-assembly into functional nanomaterials†  

PubMed Central

Calixarenes are excellent surfactants for enhancing the dispersion and self-assembly of metal nanoparticles into well-defined structures, particularly those with unit length scales in the 10–100 nm size range. Particles within these ensembles are strongly coupled, giving rise to unique collective optical or magnetic properties. The self-assembled nanostructures described in this feature article include 2D arrays of colloidal Au nanoparticles with size-dependent plasmonic responses, and sub-100 nm Co nanoparticle rings with chiral magnetic states. These nanoparticle assemblies may be further developed for applications in chemical sensing based on surface-enhanced Raman scattering (SERS) and as binary elements for nonvolatile memory, respectively.

Wei, Alexander

2007-01-01

302

Solid state switch  

DOEpatents

A solid state switch, with reverse conducting thyristors, is designed to operate at 20 kV hold-off voltage, 1500 A peak, 1.0 .mu.s pulsewidth, and 4500 pps, to replace thyratrons. The solid state switch is more reliable, more economical, and more easily repaired. The switch includes a stack of circuit card assemblies, a magnetic assist and a trigger chassis. Each circuit card assembly contains a reverse conducting thyristor, a resistor capacitor network, and triggering circuitry.

Merritt, Bernard T. (Livermore, CA); Dreifuerst, Gary R. (Livermore, CA)

1994-01-01

303

Assemblathon 2: evaluating de novo methods of genome assembly in three vertebrate species  

PubMed Central

Background The process of generating raw genome sequence data continues to become cheaper, faster, and more accurate. However, assembly of such data into high-quality, finished genome sequences remains challenging. Many genome assembly tools are available, but they differ greatly in terms of their performance (speed, scalability, hardware requirements, acceptance of newer read technologies) and in their final output (composition of assembled sequence). More importantly, it remains largely unclear how to best assess the quality of assembled genome sequences. The Assemblathon competitions are intended to assess current state-of-the-art methods in genome assembly. Results In Assemblathon 2, we provided a variety of sequence data to be assembled for three vertebrate species (a bird, a fish, and snake). This resulted in a total of 43 submitted assemblies from 21 participating teams. We evaluated these assemblies using a combination of optical map data, Fosmid sequences, and several statistical methods. From over 100 different metrics, we chose ten key measures by which to assess the overall quality of the assemblies. Conclusions Many current genome assemblers produced useful assemblies, containing a significant representation of their genes and overall genome structure. However, the high degree of variability between the entries suggests that there is still much room for improvement in the field of genome assembly and that approaches which work well in assembling the genome of one species may not necessarily work well for another.

2013-01-01

304

On Constraints in Assembly Planning  

SciTech Connect

Constraints on assembly plans vary depending on product, assembly facility, assembly volume, and many other factors. Assembly costs and other measures to optimize vary just as widely. To be effective, computer-aided assembly planning systems must allow users to express the plan selection criteria that appIy to their products and production environments. We begin this article by surveying the types of user criteria, both constraints and quality measures, that have been accepted by assembly planning systems to date. The survey is organized along several dimensions, including strategic vs. tactical criteria; manufacturing requirements VS. requirements of the automated planning process itself and the information needed to assess compliance with each criterion. The latter strongly influences the efficiency of planning. We then focus on constraints. We describe a framework to support a wide variety of user constraints for intuitive and efficient assembly planning. Our framework expresses all constraints on a sequencing level, specifying orders and conditions on part mating operations in a number of ways. Constraints are implemented as simple procedures that either accept or reject assembly operations proposed by the planner. For efficiency, some constraints are supplemented with special-purpose modifications to the planner's algorithms. Fast replanning enables an interactive plan-view-constrain-replan cycle that aids in constraint discovery and documentation. We describe an implementation of the framework in a computer-aided assembly planning system and experiments applying the system to a number of complex assemblies, including one with 472 parts.

Calton, T.L.; Jones, R.E.; Wilson, R.H.

1998-12-17

305

Special test equipment and fixturing for MSAT reflector assembly alignment  

Microsoft Academic Search

The MSAT Reflector Assembly is a state of the art subsystem for Mobile Satellite (MSAT), a geosynchronous-based commercial mobile telecommunication satellite program serving North America. The Reflector Assembly consisted of a deployable, three-hinge, folding-segment Boom, deployable 5.7 x 5.3-meter 16-rib Wrap-Rib Reflector, and a Reflector Pointing Mechanism (RPM). The MSAT spacecraft was based on a Hughes HS601 spacecraft bus carrying

Jeffrey A. Young; Michael R. Zinn; David R. McCarten

1994-01-01

306

Physics and applications of self-assembled quantum dots  

Microsoft Academic Search

Linear and nonlinear spectroscopic invsetigations of self-assembled quantum dots open up the possibility to study model quantum mechanical systems with potential applications in solid-state based quantum information processing. In this article we review recent advances in our understanding of the physics of self-assembled quantum dots and novel devices based upon them. We focus our attention on four key areas: (i)

E. Beham; M. Betz; S. Trumm; M. Kroutvar; Y. Ducommun; H. J. Krenner; M. Bichler; A. Leitenstorfer; J. J. Finley; A. Zrenner; G. Abstreiter

2004-01-01

307

Monticello BWR spent fuel assembly decay heat predictions and measurements  

Microsoft Academic Search

This report compares pre-calorimetry predictions of rates of six 7 x 7 boiling water reactor (BWR) spent fuel assemblies with measured decay heat rates. The assemblies were from Northern States Power Company's Monticello Nuclear Generating Plant and had burnups of 9 to 21 GWd\\/MTU and cooling times of 9 to 10 years. Conclusions are: The agreement between ORIGEN2 predictions and

M. A. McKinnon; J. W. Doman; C. M. Heeb; J. M. Creer

1986-01-01

308

Dynamics of Self-Assembling Systems: Analogy with Chemical Kinetics  

Microsoft Academic Search

In this article, we propose a new analyzing method for self-assembling systems. Its initial purpose was to predict the yield—the final amount of desired product—of our original self-assembling mechanical model. Moreover, the method clarifies the dynamical evolution of the system. In this method, the quantity of each intermediate product is adopted as state variables, and the dynamics that dominates the

Kazuo Hosokawa; Isao Shimoyama; Hirofumi Miura

1994-01-01

309

Removable feedwater sparger assembly  

DOEpatents

A removable feedwater sparger assembly includes a sparger having an inlet pipe disposed in flow communication with the outlet end of a supply pipe. A tubular coupling includes an annular band fixedly joined to the sparger inlet pipe and a plurality of fingers extending from the band which are removably joined to a retention flange extending from the supply pipe for maintaining the sparger inlet pipe in flow communication with the supply pipe. The fingers are elastically deflectable for allowing engagement of the sparger inlet pipe with the supply pipe and for disengagement therewith. 8 figs.

Challberg, R.C.

1994-10-04

310

Vertical blind assembly  

US Patent & Trademark Office Database

A vertical blind assembly includes an elongate header casing and two sets of louvers movably supported in adjacent channels within the header casing, including a first set of plain louvers structured to be moved horizontally along the length of the first channel, and a second set of louvers which are molded and configured in a decorative, three-dimensional pattern and structured to be moved horizontally along the length of the second channel so that they are positioned in front of the first set of louvers.

1997-01-28

311

BIOCHEMISTRY: Dicey Assemblies  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Site-directed mutagenesis allows the symmetry of protein assemblies to be directed in a systematic manner. More than 40 years ago, Jacques Monod and co-workers developed the theory of allostery that explains how the activity of proteins can be efficiently regulated. The quaternary structure allows proteins to have symmetries that play a central role in allostery. Grueninger et al. prove that this symmetry can be manipulated by site-directed mutagenesis. Their experiments confirm some of the basic arguments made by Monod et al.

Joël Janin (Institut de Biochimie et Biophysique Moléculaire et Cellulaire;Yeast Structural Genomics)

2008-01-11

312

Precision Robotic Assembly Machine  

ScienceCinema

The world's largest laser system is the National Ignition Facility (NIF), located at Lawrence Livermore National Laboratory. NIF's 192 laser beams are amplified to extremely high energy, and then focused onto a tiny target about the size of a BB, containing frozen hydrogen gas. The target must be perfectly machined to incredibly demanding specifications. The Laboratory's scientists and engineers have developed a device called the "Precision Robotic Assembly Machine" for this purpose. Its unique design won a prestigious R&D-100 award from R&D Magazine.

None

2010-09-01

313

Robotic Thumb Assembly  

NASA Technical Reports Server (NTRS)

An improved robotic thumb for a robotic hand assembly is provided. According to one aspect of the disclosure, improved tendon routing in the robotic thumb provides control of four degrees of freedom with only five tendons. According to another aspect of the disclosure, one of the five degrees of freedom of a human thumb is replaced in the robotic thumb with a permanent twist in the shape of a phalange. According to yet another aspect of the disclosure, a position sensor includes a magnet having two portions shaped as circle segments with different center points. The magnet provides a linearized output from a Hall effect sensor.

Ihrke, Chris A. (Inventor); Bridgwater, Lyndon (Inventor); Platt, Robert (Inventor); Wampler, II, Charles W. (Inventor); Goza, S. Michael (Inventor)

2013-01-01

314

Removable feedwater sparger assembly  

DOEpatents

A removable feedwater sparger assembly includes a sparger having an inlet pipe disposed in flow communication with the outlet end of a supply pipe. A tubular coupling includes an annular band fixedly joined to the sparger inlet pipe and a plurality of fingers extending from the band which are removably joined to a retention flange extending from the supply pipe for maintaining the sparger inlet pipe in flow communication with the supply pipe. The fingers are elastically deflectable for allowing engagement of the sparger inlet pipe with the supply pipe and for disengagement therewith.

Challberg, Roy C. (Livermore, CA)

1994-01-01

315

Precision Robotic Assembly Machine  

SciTech Connect

The world's largest laser system is the National Ignition Facility (NIF), located at Lawrence Livermore National Laboratory. NIF's 192 laser beams are amplified to extremely high energy, and then focused onto a tiny target about the size of a BB, containing frozen hydrogen gas. The target must be perfectly machined to incredibly demanding specifications. The Laboratory's scientists and engineers have developed a device called the "Precision Robotic Assembly Machine" for this purpose. Its unique design won a prestigious R&D-100 award from R&D Magazine.

2009-08-14

316

Installation and assembly device and method of using  

DOEpatents

An installation and assembly device for aligning a first member such as a pump impeller with a second member such as an inlet nozzle of an impeller pump. The installation and assembly device includes a sleeve slideable within the inlet nozzle and a vertical positioning assembly which has a contact member that is extendable out away from the sleeve so as to vertically position the sleeve on a shoulder of the inlet nozzle and to present an upper contact surface spaced a certain distance from the shoulder to provide the desired vertical spacing with respect to the impeller contacting the upper contact surface. The vertical positioning assembly is retractable so as to allow for removal of the sleeve through the nozzle when installation and assembly are completed. The alignment device also includes a radial alignment assembly supported by the sleeve and adjustable to an expanded state for contacting and spacing the interior surface of the impeller a certain distance from the sleeve and hence a certain distance from the inlet nozzle. The radial alignment device being adjustable from a retracted removal state to an expanded state and also being adjustable to fine tune the spacing of the impeller from the sleeve. The radial alignment device also preferably includes members that can be used to releasably secure the sleeve to the impeller.

Kolsun, George J. (Pittsburgh, PA)

1997-01-01

317

Installation and assembly device and method of using  

SciTech Connect

An installation and assembly device are disclosed for aligning a first member such as a pump impeller with a second member such as an inlet nozzle of an impeller pump. The installation and assembly device includes a sleeve slideable within the inlet nozzle and a vertical positioning assembly which has a contact member that is extendable out away from the sleeve so as to vertically position the sleeve on a shoulder of the inlet nozzle and to present an upper contact surface spaced a certain distance from the shoulder to provide the desired vertical spacing with respect to the impeller contacting the upper contact surface. The vertical positioning assembly is retractable so as to allow for removal of the sleeve through the nozzle when installation and assembly are completed. The alignment device also includes a radial alignment assembly supported by the sleeve and adjustable to an expanded state for contacting and spacing the interior surface of the impeller a certain distance from the sleeve and hence a certain distance from the inlet nozzle. The radial alignment device being adjustable from a retracted removal state to an expanded state and also being adjustable to fine tune the spacing of the impeller from the sleeve. The radial alignment device also preferably includes members that can be used to releasably secure the sleeve to the impeller. 4 figs.

Kolsun, G.J.

1997-09-16

318

Multicomponent assembly of nanocrystals  

NASA Astrophysics Data System (ADS)

We have developed chemical-based methods to produce binary assemblies of nanocrystals. The ordered arrays that result are superlattices that mimic the structures of known crystal phases. Applications of this new type of material extends into the realm of optical science and technology. The model is of single component nanocrystals in the 5-20 nm range, which build multicomponent structures of micrometer dimensions. The method presents the opportunity to choose from a variety of inorganic nanocrystals (e.g. semiconducting, magnetic) in order to prepare superlattices with uniquely tunable properties. Transition metal and transition metal oxide nanocrystals are nanometer dimension crystals composed of one or more metals from the d block of the periodic table, and oxygen. The nanocrystals have capping groups which render them discrete, stable, and enable them to be manipulated in a variety of media such as solvents or polymers. The nanocrystals are ideally monodisperse, uniform in composition, crystalline, and can be prepared over a range of sizes from 5-20 nm. The selection of composition for the nanocrystals is based on materials with known interesting properties (optical, electronic or electrical) in the bulk phase. Once fully characterized, the nanocrystals can be considered as components for the assembly of a nanostructured composite material designed to exhibit interesting collective properties with tunable control at the nanoscale.

Shevchenko, Elena; Redl, Franz; Yin, Ming; Murray, Christopher B.; O'Brien, Stephen P.

2004-10-01

319

Modular impact ripper assembly  

SciTech Connect

An improved ripper assembly (12) is joined to and drawn by a draft device (10) and includes a mounting structure (14), a ripper element (16), and an impactor apparatus (18). The mounting structure (14) includes an upper flange (20) and a lower flange (22) joined together by a pair of side plates (23). Aligned openings (24,26) in the flanges (20,22) permit attachment thereof to the draft device (10) and allows pivoting about a vertical pivot axis (28) when pins (30,32) are installed. The ripper element (16) is pivotable about a horizontal pivot axis (38) and is secured to the mounting structure (14) by a pivot pin (40). The impact apparatus (18) imparts intermittent blows to the ripper element (16) and is joined to the mounting structure (14) by a single upper support pin (44) and two, aligned lower support pins (46). The upper and lower support pins (44,46) are disposed adjacent the upper and lower flanges (20,22), respectively, while the pivot axis (38) extends through the side plates (23) intermediate the upper and lower flanges (20,22). The relative disposition of the component interconnections of the impact ripper assembly (12) and the independent nature of the connections permit separate removal of the ripper element (16) and/or the impactor apparatus (18).

Roussin, M.A.

1984-06-12

320

Measuring electrode assembly  

SciTech Connect

A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture.

Bordenick, John E. (West Mifflin, PA)

1989-01-01

321

Measuring electrode assembly  

DOEpatents

A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture. 2 figs.

Bordenick, J.E.

1988-04-26

322

Bottom head assembly  

DOEpatents

A bottom head dome assembly which includes, in one embodiment, a bottom head dome and a liner configured to be positioned proximate the bottom head dome is described. The bottom head dome has a plurality of openings extending therethrough. The liner also has a plurality of openings extending therethrough, and each liner opening aligns with a respective bottom head dome opening. A seal is formed, such as by welding, between the liner and the bottom head dome to resist entry of water between the liner and the bottom head dome at the edge of the liner. In the one embodiment, a plurality of stub tubes are secured to the liner. Each stub tube has a bore extending therethrough, and each stub tube bore is coaxially aligned with a respective liner opening. A seat portion is formed by each liner opening for receiving a portion of the respective stub tube. The assembly also includes a plurality of support shims positioned between the bottom head dome and the liner for supporting the liner. In one embodiment, each support shim includes a support stub having a bore therethrough, and each support stub bore aligns with a respective bottom head dome opening.

Fife, Alex Blair (San Jose, CA)

1998-01-01

323

Bottom head assembly  

DOEpatents

A bottom head dome assembly is described which includes, in one embodiment, a bottom head dome and a liner configured to be positioned proximate the bottom head dome. The bottom head dome has a plurality of openings extending there through. The liner also has a plurality of openings extending there through, and each liner opening aligns with a respective bottom head dome opening. A seal is formed, such as by welding, between the liner and the bottom head dome to resist entry of water between the liner and the bottom head dome at the edge of the liner. In the one embodiment, a plurality of stub tubes are secured to the liner. Each stub tube has a bore extending there through, and each stub tube bore is coaxially aligned with a respective liner opening. A seat portion is formed by each liner opening for receiving a portion of the respective stub tube. The assembly also includes a plurality of support shims positioned between the bottom head dome and the liner for supporting the liner. In one embodiment, each support shim includes a support stub having a bore there through, and each support stub bore aligns with a respective bottom head dome opening. 2 figs.

Fife, A.B.

1998-09-01

324

Self-Assembling Dessert Toppings  

NSDL National Science Digital Library

This is an activity (located on page 3 of the PDF) about self-assembly, the ability of molecules to assemble themselves according to certain rules. Learners will use food-grade components to create delicious dessert topping-filled gel capsules, macroscale relatives of the capsules nanoscientists make in a lab to carry medicine to targeted cells of the body. Relates to linked video, DragonflyTV Nano: Self-Assembly.

Twin Cities Public Television, Inc.

2008-01-01

325

Transplanting Assembly of Carbon Nanotubes  

Microsoft Academic Search

The manufacture of nanotechnology products requires assembly of nano scale components to macro\\/micro-scale systems, which is a major challenge in attempting to industrialize nanotechnologies. A new approach to assemble nanostructures is developed with a control of individual nanostructure's location and alignment in a long-range order. A concept of transplanting assembly has been developed to embed carbon nanotubes into micro-scale polymer

S. G. Kim

2006-01-01

326

Gas separation membrane module assembly  

DOEpatents

A gas-separation membrane module assembly and a gas-separation process using the assembly. The assembly includes a set of tubes, each containing gas-separation membranes, arranged within a housing. The housing contains a tube sheet that divides the space within the housing into two gas-tight spaces. A permeate collection system within the housing gathers permeate gas from the tubes for discharge from the housing.

Wynn, Nicholas P (Palo Alto, CA); Fulton, Donald A. (Fairfield, CA)

2009-03-31

327

Fuel Assembly Nonlinear Dynamic Model  

SciTech Connect

Fuel assembly finite-element dynamic models are developed to perform the core seismic analysis. The fuel assembly is modeled by a single vertical beam, which represents the cross-sectional inertias of the fuel rods, guide thimbles and instrument thimble, and a series of rotational springs. The rotational springs are located at the intermediate spacer grid locations. Benchmarking to fuel assembly natural frequencies determined by testing is accomplished by adjusting the moment of inertia and the grid rotational stiffness to find their effective values. Most often these models are linear and are appropriate for the small amplitude stiffness representation of the fuel assembly. Large deflection problems are approximated by choosing a fuel assembly stiffness value appropriate to the average deflection range. Some loss of accuracy will naturally result from this approach. This paper presents a nonlinear model to approximate the hysteresis and free vibration response for large amplitudes fuel assembly motion. The force required to impose the initial displacement (pluck) and the free vibration responses are used to compare the nonlinear model's behavior with the test data. This model correctly predicts fuel assembly deflection shapes as a function of axial position for various lateral loads for several fuel assembly designs. Displacement hysteresis is primarily due to fuel assembly to grid slippage, which is a strong function of grid preload. 'Tight' and 'relaxed' prototypes were tested to account for grid preload effect. The model correctly analyzes the grid preload effect. A nonlinear fuel assembly model provides better matching of grid impact loads determined by fuel assembly lateral impact testing and also provides better matching of all of the initial conditions (initial deflection, initial force, initial energy and impact velocity). In this test, the fuel assembly impacts a test wall to determine grid internal stiffness. This value is used in the core model for seismic analyses. (authors)

Shah, S.J.; Brenneman, B. [Framatome ANP, P.O. Box 10935 P.O. Box 10935, Lynchburg, VA-24506-0935 (United States)

2002-07-01

328

Supramolecular Assembly of Biohybrid Photoconversion Systems  

SciTech Connect

Self-assembled membrane architectures have great potential for the development of materials for the conversion of solar energy into electricity or fuels. Discovering the design principles that promote self-assembly in natural photosynthetic systems may provide inspiration for the development of synthetic solar conversion systems. We report for the first time that naturally occurring light harvesting antennae can alter the phase behavior of a poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer system from micellar to lamellar structures mimicking their role in maintaining the supramolecular architecture of the photosynthetic membrane. Small-angle neutron scattering shows that PEO{sub 43}-PPO{sub 16}-PEO{sub 43} micelles undergo a phase transition from a micellar state to a lamellar structure with a {approx}60 {angstrom} spatial repetition in the presence of plant light harvesting complex II (LHCII). In addition, spectrophotometric analysis indicates that the protein self-assembles in the synthetic membrane structure. Photodependent hydrogen production mediated by LHCII embedded in the block copolymer had a maximum rate of 6.4 {micro}mol h{sup -1} per mg chlorophyll. The production of H{sub 2} was sustained for greater than 100 hours showing the potential of this approach for the development of self-assembled bioinspired photoconversion systems. Although excited energy transfer is the primary function of LHCII, this work provides evidence that the protein complex can also perform electron transfer, a role not known to occur in vivo. The significance of this work is that it provides a novel approach for developing a new class of membrane-based smart material with a well-controlled architecture that is dependent on the assembly of interacting components, and it could also have important implications in self-repair and control of energy transfer in photoconversion devices.

Cardoso, Mateus B [ORNL; Smolensky, Dmitriy [ORNL; Heller, William T [ORNL; Hong, Kunlun [ORNL; O'Neill, Hugh Michael [ORNL

2011-01-01

329

Airfoil nozzle and shroud assembly  

DOEpatents

An airfoil and nozzle assembly including an outer shroud having a plurality of vane members attached to an inner surface and having a cantilevered end. The assembly further includes a inner shroud being formed by a plurality of segments. Each of the segments having a first end and a second end and having a recess positioned in each of the ends. The cantilevered end of the vane member being positioned in the recess. The airfoil and nozzle assembly being made from a material having a lower rate of thermal expansion than that of the components to which the airfoil and nozzle assembly is attached.

Shaffer, James E. (Maitland, FL); Norton, Paul F. (San Diego, CA)

1997-01-01

330

Airfoil nozzle and shroud assembly  

DOEpatents

An airfoil and nozzle assembly are disclosed including an outer shroud having a plurality of vane members attached to an inner surface and having a cantilevered end. The assembly further includes a inner shroud being formed by a plurality of segments. Each of the segments having a first end and a second end and having a recess positioned in each of the ends. The cantilevered end of the vane member being positioned in the recess. The airfoil and nozzle assembly being made from a material having a lower rate of thermal expansion than that of the components to which the airfoil and nozzle assembly is attached. 5 figs.

Shaffer, J.E.; Norton, P.F.

1997-06-03

331

Clean then Assemble Versus Assemble then Clean: Several Comparisons  

NASA Technical Reports Server (NTRS)

Cleanliness of manufactured parts and assemblies is a significant issue in many industries including disk drives, semiconductors, aerospace, and medical devices. Clean manufacturing requires cleanroom floor space and cleaning technology that are both expensive to own and expensive to operate. Strategies to reduce these costs are an important consideration. One strategy shown to be effective at reducing costs is to assemble parts into subassemblies and then clean the subassembly, rather than clean the individual parts first and then assemble them. One advantage is that assembly outside of the cleanroom reduces the amount of cleanroom floor space and its associated operating cost premium. A second advantage is that this strategy reduces the number of individual parts that must be cleaned prior to assembly, reducing the number of cleaning baskets, handling and, possibly, reducing the number of cleaners. The assemble then clean strategy also results in a part that is significantly cleaner because contamination generated during the assembly steps are more effectively removed that normally can be achieved by hand wiping after assembly in the cleanroom.

Welker, Roger W.

2004-01-01

332

Method and apparatus for assembling a permanent magnet pole assembly  

DOEpatents

A pole assembly for a rotor, the pole assembly includes a permanent magnet pole including at least one permanent magnet block, a plurality of laminations including a pole cap mechanically coupled to the pole, and a plurality of laminations including a base plate mechanically coupled to the pole.

Carl, Jr., Ralph James (Clifton Park, NY); Bagepalli, Bharat Sampathkumaran (Niskayuna, NY); Jansen, Patrick Lee (Scotia, NY); Dawson, Richard Nils (Voorheesville, NY); Qu, Ronghai (Clifton Park, NY); Avanesov, Mikhail Avramovich (Moscow, RU)

2009-08-11

333

Restructuring the Common School in Ohio: The Path to Educational Progress. Policy and Budget Recommendations of the State Board of Education to the Governor and 119th General Assembly.  

ERIC Educational Resources Information Center

When the Ohio State Board of Education began developing legislative recommendations for the 1992-93 biennium, the state's economic outlook was more positive. However, conditions changed dramatically and the state faced a budget deficit. While recognizing these economic limitations, the board proposed that the education system must move toward…

Ohio State Dept. of Education, Columbus.

334

Propulsion system assembly  

SciTech Connect

A propulsion system assembly for a vehicle is described having an engine and a nacelle disposed about the engine which has an exterior which comprises: a shroud disposed circumferentially about the nacelle which is spaced radially from the nacelle leaving an opening there between for cooling air from the exterior of the nacelle; structure which extends radially upstream of the opening to block flow from entering the opening, the structure extending between the shroud and nacelle and having at least one under cut portion forming a passage which diverges in the axial direction and which begins upstream of the opening and is bounded by an axially extending wall on the structure; wherein the passage provides a flow path to duct air from the exterior of the nacelle to a location downstream of the blocked portion of the opening on the interior of the shroud.

Zysmaan, S.H.

1993-06-08

335

Flexible cloth seal assembly  

DOEpatents

A seal assembly having a flexible cloth seal which includes a shim assemblage surrounded by a cloth assemblage. A first tubular end portion, such as a gas turbine combustor, includes a longitudinal axis and has smooth and spaced-apart first and second surface portions defining a notch therebetween which is wider at its top than at its bottom and which extends outward from the axis. The second surface portion is outside curved, and a first edge of the cloth seal is positioned in the bottom of the notch. A second tubular end portion, such as a first stage nozzle, is located near, spaced apart from, and coaxially aligned with, the first tubular end portion. The second tubular end portion has a smooth third surface portion which surrounds at least a portion of the first tubular end portion and which is contacted by the cloth seal.

Bagepalli, Bharat Sampathkumar (Niskayuna, NY); Taura, Joseph Charles (Clifton Park, NY); Aksit, Mahmut Faruk (Troy, NY); Demiroglu, Mehmet (Troy, NY); Predmore, Daniel Ross (Clifton Park, NY)

1999-01-01

336

Rotatable seal assembly  

DOEpatents

An assembly is provided for rotatably supporting a rotor on a stator so that vacuum chambers in the rotor and stator remain in communication while the chambers are sealed from ambient air, which enables the use of a ball bearing or the like to support most of the weight of the rotor. The apparatus includes a seal device mounted on the rotor to rotate therewith, but shiftable in position on the rotor while being sealed to the rotor as by an O-ring. The seal device has a flat face that is biased towards a flat face on the stator, and pressurized air is pumped between the faces to prevent contact between them while spacing them a small distance apart to avoid the inflow of large amounts of air between the faces and into the vacuum chambers.

Logan, Clinton M. (Pleasanton, CA); Garibaldi, Jack L. (Livermore, CA)

1982-01-01

337

Automated optical assembly  

NASA Astrophysics Data System (ADS)

Automation and polymer science represent fundamental new technologies which can be directed toward realizing the goal of establishing a domestic, world-class, commercial optics business. Use of innovative optical designs using precision polymer optics will enable the US to play a vital role in the next generation of commercial optical products. The increased cost savings inherent in the utilization of optical-grade polymers outweighs almost every advantage of using glass for high volume situations. Optical designers must gain experience with combined refractive/diffractive designs and broaden their knowledge base regarding polymer technology beyond a cursory intellectual exercise. Implementation of a fully automated assembly system, combined with utilization of polymer optics, constitutes the type of integrated manufacturing process which will enable the US to successfully compete with the low-cost labor employed in the Far East, as well as to produce an equivalent product.

Bala, John L.

1995-08-01

338

Nuclear fuel assembly  

SciTech Connect

The fuel assembly comprises a bundle of fuel pins spaced in parallel relation in a uniform lattice by means of support grids resiliently applied against the fuel pins and a rigid independent structure formed by two parallel end plates. Tie-rods extending between the end plates are disposed at uniform intervals at the lattice nodes. The bundle of fuel pins is supported by the first grid on a series of tubular spacer members which surround the lower ends of at least a number of tie-rods with provision for a clearance space. The tubular spacer members extend between the bottom end plate and the first grid, the tie-rods being permitted to pass freely through each grid by means of guide sleeves.

Delafosse, J.

1980-12-23

339

Crank shaft support assembly  

DOEpatents

A crank shaft support assembly for increasing stiffness and reducing thermal mismatch distortion in a crank shaft bore of an engine comprising different materials. A cylinder block comprises a first material and at least two crank journal inserts are insert-molded into respective crank journal regions of the cylinder block and comprise a second material having greater stiffness and a lower thermal coefficient of expansion that the first material. At least two bearing caps are bolted to the respective crank journal inserts and define, along with the crank journal inserts, at least two crank shaft support rings defining a crank shaft bore coaxially aligned with a crank shaft axis. The bearing caps comprise a material having higher stiffness and a lower thermal coefficient of expansion than the first material and are supported on the respective crank journal inserts independently of any direct connection to the cylinder block.

Natkin, Robert J. (Canton, MI); Oltmans, Bret (Stacy, MN); Allison, John E. (Ann Arbor, MI); Heater, Thomas J. (Milford, MI); Hines, Joy Adair (Plymouth, MI); Tappen, Grant K. (Washington, MI); Peiskammer, Dietmar (Rochester, MI)

2007-10-23

340

Flexible cloth seal assembly  

DOEpatents

A seal assembly is described having a flexible cloth seal which includes a shim assemblage surrounded by a cloth assemblage. A first tubular end portion, such as a gas turbine combustor, includes a longitudinal axis and has smooth and spaced-apart first and second surface portions defining a notch there between which is wider at its top than at its bottom and which extends outward from the axis. The second surface portion is outside curved, and a first edge of the cloth seal is positioned in the bottom of the notch. A second tubular end portion, such as a first stage nozzle, is located near, spaced apart from, and coaxially aligned with, the first tubular end portion. The second tubular end portion has a smooth third surface portion which surrounds at least a portion of the first tubular end portion and which is contacted by the cloth seal. 7 figs.

Bagepalli, B.S.; Taura, J.C.; Aksit, M.F.; Demiroglu, M.; Predmore, D.R.

1999-06-29

341

Conformational Changes in the Hepatitis B Virus Core Protein Are Consistent with a Role for Allostery in Virus Assembly  

SciTech Connect

In infected cells, virus components must be organized at the right place and time to ensure assembly of infectious virions. From a different perspective, assembly must be prevented until all components are available. Hypothetically, this can be achieved by allosterically controlling assembly. Consistent with this hypothesis, here we show that the structure of the hepatitis B virus (HBV) core protein dimer, which can spontaneously self-assemble, is incompatible with capsid assembly. Systematic differences between core protein dimer and capsid conformations demonstrate linkage between the intradimer interface and interdimer contact surface. These structures also provide explanations for the capsid-dimer selectivity of some antibodies and the activities of assembly effectors. Solution studies suggest that the assembly-inactive state is more accurately an ensemble of conformations. Simulations show that allostery supports controlled assembly and results in capsids that are resistant to dissociation. We propose that allostery, as demonstrated in HBV, is common to most self-assembling viruses.

Packianathan, Charles; Katen, Sarah P.; Dann, III, Charles E.; Zlotnick, Adam (Indiana)

2010-01-12

342

Electrical Transport in Semiconductor Nanocrystal Assemblies  

NASA Astrophysics Data System (ADS)

The size-tunable electronic properties and the solution processability of colloidal semiconductor nanocrystals (NCs) have made these materials promising candidates for thin-film optoelectronics. In particular, the tunable absorption and emission of NCs can potentially allow solar cells, light emitting diodes, and photodetectors to be optimized systematically. Towards these applications, significant progress has been made in understanding optical properties of NCs as well as in development of synthetic methods to prepare monodisperse NCs. Despite all the excitement surrounding the potential use of NCs, however, successful incorporation of these materials into practical devices is still challenging since assemblies of NCs are not highly conductive. Also, compared to the extensive studies on optical properties, the charge transport in NC assemblies has been much less explored. Considering that most of these devices typically involve charge conduction between NCs, their charge transport properties should also be well-understood. Furthermore, methods to obtain highly conductive NC assemblies should be developed. These will lead to improved device performance that takes full advantage of the characteristic properties of NCs in optoelectronic applications. To address these issues, the electrical transport properties of NC assemblies are investigated comprehensively in this thesis. Throughout the entire study, a transistor device structure was employed to control charge density in NC films. To begin with, the charge transport mechanism in films of different sized PbSe NCs was examined at varying temperatures. We observed that the electron transport between NCs underwent a transition in mechanism from Efros-Shklovskii-variable-range-hopping (ES-VRH) to nearest-neighbor-hopping (NNH). Interestingly, this transition in the mechanism was NC size-dependent, such that it occurred at higher temperatures for films with smaller NCs. We also observed that the electron localization length, estimated from the ES-VRH model, was comparable to the NC size and scaled systematically with NC diameter. Furthermore, the activation energy from the NNH regime was also size-dependent which is attributed both to the size-dependent Coulomb effects and the size-distribution of NCs. Following, the influence of NC size on the charge transport in CdSe NC assemblies was investigated by employing electrolyte gating. We found that the transport parameters in CdSe NC assemblies also varied strongly and systematically with NC diameter. First, a strong correlation was observed between the device turn-on voltage and the size-dependent position of the lowest unoccupied electronic states of NCs. Second, the electron mobility increased with increasing particle diameter. Third, the charge transport following the NNH model exhibited a size-dependent activation energy and a pre-exponential factor for mobility, consistent with the result from PbSe NC assemblies. Towards improving the electrical conduction in NC assemblies, electrical transport in doped NC assemblies was examined and compared with the results of undoped NC assemblies. The charge transport activation energy obtained within the NNH temperature regime for PbSe NC films was reduced by incorporating Ag atoms into PbSe NCs, which is probably due to the reduced Coulomb penalty for hopping processes. Also, the device turn-on voltage revealed that the Fermi level is shifted upon doping CdSe NCs with either Ag or Al atoms. Ag atoms raised the Fermi level closer to the electron transport level ( n-type doping) with initial doping but then lowered the Fermi level (p-type doping) with further doping. Meanwhile, Al atoms only raised the Fermi level closer to the electron transport level ( n-type doping). Also, a corresponding change in the electron mobility was observed with doping such that the electron mobility of CdSe NC films decreased with p-type doping and increased with n-type doping. Finally, one potential application of transistors based on NCs is discussed, namely the light-emitting transistors (LETs), which

Kang, Moon Sung

343

Solution assembly of conjugated polymers  

NASA Astrophysics Data System (ADS)

This dissertation focuses on the solution-state polymer assembly of conjugated polymers with specific attention to nano- and molecular-scale morphology. Understanding how to control these structures holds potential for applications in polymer-based electronics. Optimization of conjugated polymer morphology was performed with three objectives: 1) segregation of donor and acceptor materials on the nanometer length-scale, 2) achieving molecular-scale ordering in terms of crystallinity within distinct domains, and 3) maximizing the number and quality of well-defined donor/acceptor interfaces. Chapter 1 introduces the development of a mixed solvent method to create crystalline poly(3-hexyl thiophene) (P3HT) fibrils in solution. Chapter 2 describes fibril purification and approaches to robust and functional fibrils, while chapters 3 and 4 demonstrate the formation of hybrid nanocomposite wires of P3HT and cadmium selenide (CdSe) nanoparticles by two methods: 1) co-crystallization of free and P3HT-grafted CdSe for composite nanowires and 2) direct attachment of CdSe nanoparticles at fibril edges to give superhighway structures. These composite structures show great potential in the application of optoelectronic devices, such as the active layer of solar cells. Finally, ultrafast photophysical characterization of these polymers, using time-resolved photoluminescence and transient absorption, was performed to determine the aggregation types present in suspended fibrils and monitor the formation and decay of charged species in fibrils and donor-acceptor systems.

Bokel, Felicia A.

344

Well-type scintillation assembly  

Microsoft Academic Search

A scintillation detector assembly is described which employs a scintillation phosphor such as a thallium activated sodium iodide crystal, wherein a blind hole is machined in the crystal to improve the efficiency of measuring the degradation rate of a radioactive material placed therein. The performance of the assembly is defined by the energy resolution of the radiation emanating from the

M. R. Farukhi; G. A. Mataraza; O. D. Wimer

1978-01-01

345

Stator and method of assembly  

DOEpatents

The present application provides a stator. The stator may include a number of poles and a stator tip and cooling assembly. The stator tip and cooling assembly may include a number of stator tips with a number of cooling tubes adjacent thereto such that the stator tips align with the poles and the cooling tubes cool the poles.

Alexander, James Pellegrino; El-Refaie, Ayman Mohamed Fawzi; Shen, Xiaochun

2013-06-18

346

Pulse Assembly for Reactor Control  

Microsoft Academic Search

This assembly is connected to pulse neutron detectors: fission chamber, BF3 counter, boron counter. No preamplifier is needed. The input impedance of the amplifier is matched to the impedance of the coaxial cable connected to the detector. The assembly can work with a length of cable between the detector and the electronics as long as 200 meters. The effects of

J. Buisson; J. Garau

1967-01-01

347

Los Alamos Critical Assemblies Facility.  

National Technical Information Service (NTIS)

The Critical Assemblies Facility of the Los Alamos National Laboratory has been in existence for thirty-five years. In that period, many thousands of measurements have been made on assemblies of exp 235 U, exp 233 U, and exp 239 Pu in various configuratio...

R. E. Malenfant

1981-01-01

348

Three dimensional colorimetric assay assemblies  

SciTech Connect

A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.

Charych, D.; Reichart, A.

2000-06-27

349

Three dimensional colorimetric assay assemblies  

DOEpatents

A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.

Charych, Deborah (Albany, CA); Reichart, Anke (Albany, CA)

2000-01-01

350

Advanced gray rod control assembly  

DOEpatents

An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

Drudy, Keith J; Carlson, William R; Conner, Michael E; Goldenfield, Mark; Hone, Michael J; Long, Jr., Carroll J; Parkinson, Jerod; Pomirleanu, Radu O

2013-09-17

351

Virus assembly, allostery, and antivirals  

PubMed Central

Assembly of virus capsids and surface proteins must be regulated to ensure that the resulting complex is an infectious virion. Here we examine assembly of virus capsids, focusing on hepatitis B virus and bacteriophage MS2, and formation of glycoproteins in the alphaviruses. These systems are structurally and biochemically well-characterized and are simplest-case paradigms of self-assembly. Published data suggest that capsid and glycoprotein assembly is subject to allosteric regulation, that is, regulation at the level of conformational change. The hypothesis that allostery is a common theme in viruses suggests that deregulation of capsid and glycoprotein assembly by small molecule effectors will be an attractive antiviral strategy, as has been demonstrated with hepatitis B virus.

Zlotnick, Adam; Mukhopadhyay, Suchetana

2010-01-01

352

Assembly of surface engineered nanoparticles for functional materials  

NASA Astrophysics Data System (ADS)

Nanoparticles are regarded as exciting new building blocks for functional materials due to their fascinating physical properties because of the nano-confinement. Organizing nanoparticles into ordered hierarchical structures are highly desired for constructing novel optical and electrical artificial materials that are different from their isolated state or thermodynamics random ensembles. My research integrates the surface chemistry of nanoparticles, interfacial assembly and lithography techniques to construct nanoparticle based functional structures. We designed and synthesized tailor-made ligands for gold, semiconductor and magnetic nanoparticle, to modulate the assembly process and collective properties of the assembled structures, by controlling the key parameters such as particle-interface interaction, dielectric environments and inter-particle coupling etc. Top-down technologies such as micro contact printing, photolithography and nanoimprint lithography are used to guide the assembly into arbitrarily predesigned structures for potential device applications.

Yu, Xi

353

Reconstitution of Outer Membrane Protein Assembly from Purified Components  

PubMed Central

?-barrel membrane proteins in Gram-negative bacteria, mitochondria, and chloroplasts are assembled by highly conserved multi-protein complexes. The mechanism by which these molecular machines fold and insert their substrates is poorly understood. It has not been possible to dissect the folding and insertion pathway because the process has not been reproduced in a biochemical system. We purified the components that fold and insert E. coli outer membrane proteins and reconstituted ?-barrel protein assembly in proteoliposomes using the enzymatic activity of a protein substrate to report on its folding state. The assembly of this protein occurred without an energy source but required a soluble chaperone in addition to the multi-protein assembly complex.

Hagan, Christine L.; Kim, Seokhee; Kahne, Daniel

2010-01-01

354

Biogenesis and Assembly of Eukaryotic Cytochrome c Oxidase Catalytic Core  

PubMed Central

Eukaryotic cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial respiratory chain. COX is a multimeric enzyme formed by subunits of dual genetic origin which assembly is intricate and highly regulated. The COX catalytic core is formed by three mitochondrial DNA encoded subunits, Cox1, Cox2 and Cox3, conserved in the bacterial enzyme. Their biogenesis requires the action of messenger-specific and subunit-specific factors which facilitate the synthesis, membrane insertion, maturation or assembly of the core subunits. The study of yeast strains and human cell lines from patients carrying mutations in structural subunits and COX assembly factors has been invaluable to identify these ancillary factors. Here we review the current state of knowledge of the biogenesis and assembly of the eukaryotic COX catalytic core and discuss the degree of conservation of the players and mechanisms operating from yeast to human.

Soto, Ileana C.; Fontanesi, Flavia; Liu, Jingjing; Barrientos, Antoni

2011-01-01

355

AND/OR graph representation of assembly plans  

NASA Technical Reports Server (NTRS)

A compact representation of all possible assembly plans of a product using AND/OR graphs is presented as a basis for efficient planning algorithms that allow an intelligent robot to pick a course of action according to instantaneous conditions. The AND/OR graph is equivalent to a state transition graph but requires fewer nodes and simplifies the search for feasible plans. Three applications are discussed: (1) the preselection of the best assembly plan, (2) the recovery from execution errors, and (3) the opportunistic scheduling of tasks. An example of an assembly with four parts illustrates the use of the AND/OR graph representation in assembly-plan preselection, based on the weighting of operations according to complexity of manipulation and stability of subassemblies. A hypothetical error situation is discussed to show how a bottom-up search of the AND/OR graph leads to an efficient recovery.

Homem De Mello, Luiz S.; Sanderson, Arthur C.

1990-01-01

356

AND/OR graph representation of assembly plans  

NASA Astrophysics Data System (ADS)

A compact representation of all possible assembly plans of a product using AND/OR graphs is presented as a basis for efficient planning algorithms that allow an intelligent robot to pick a course of action according to instantaneous conditions. The AND/OR graph is equivalent to a state transition graph but requires fewer nodes and simplifies the search for feasible plans. Three applications are discussed: (1) the preselection of the best assembly plan, (2) the recovery from execution errors, and (3) the opportunistic scheduling of tasks. An example of an assembly with four parts illustrates the use of the AND/OR graph representation in assembly-plan preselection, based on the weighting of operations according to complexity of manipulation and stability of subassemblies. A hypothetical error situation is discussed to show how a bottom-up search of the AND/OR graph leads to an efficient recovery.

Homem de Mello, Luiz S.; Sanderson, Arthur C.

1990-04-01

357

De novo assembly of highly diverse viral populations  

PubMed Central

Background Extensive genetic diversity in viral populations within infected hosts and the divergence of variants from existing reference genomes impede the analysis of deep viral sequencing data. A de novo population consensus assembly is valuable both as a single linear representation of the population and as a backbone on which intra-host variants can be accurately mapped. The availability of consensus assemblies and robustly mapped variants are crucial to the genetic study of viral disease progression, transmission dynamics, and viral evolution. Existing de novo assembly techniques fail to robustly assemble ultra-deep sequence data from genetically heterogeneous populations such as viruses into full-length genomes due to the presence of extensive genetic variability, contaminants, and variable sequence coverage. Results We present VICUNA, a de novo assembly algorithm suitable for generating consensus assemblies from genetically heterogeneous populations. We demonstrate its effectiveness on Dengue, Human Immunodeficiency and West Nile viral populations, representing a range of intra-host diversity. Compared to state-of-the-art assemblers designed for haploid or diploid systems, VICUNA recovers full-length consensus and captures insertion/deletion polymorphisms in diverse samples. Final assemblies maintain a high base calling accuracy. VICUNA program is publicly available at: http://www.broadinstitute.org/scientific-community/science/projects/viral-genomics/ viral-genomics-analysis-software. Conclusions We developed VICUNA, a publicly available software tool, that enables consensus assembly of ultra-deep sequence derived from diverse viral populations. While VICUNA was developed for the analysis of viral populations, its application to other heterogeneous sequence data sets such as metagenomic or tumor cell population samples may prove beneficial in these fields of research.

2012-01-01

358

Assembly of user systems at Space Station  

NASA Technical Reports Server (NTRS)

The technical and programmatic benefits of on-orbit assembly are outlined. Operational and automation considerations relating to on-orbit assembly are reviewed. Space Station capabilities for orbital assembly are discussed.

Cline, Helmut P.; Lavigna, Thomas A.

1987-01-01

359

D0 Silicon Upgrade: Ladder Assembly Sequences.  

National Technical Information Service (NTIS)

This is an abridged version of the assembly sequence described by the DO assembly subgroup of Cooper, Hrycyk, Kowalski, Rapidis, and Ratzmann. This primarily is used to indicate major steps during the sequence and to list fixturing requirements. Assembly ...

P. Ratzmann

1994-01-01

360

Self-assembled biomimetic superhydrophobic hierarchical arrays.  

PubMed

Here, we report a simple and inexpensive bottom-up technology for fabricating superhydrophobic coatings with hierarchical micro-/nano-structures, which are inspired by the binary periodic structure found on the superhydrophobic compound eyes of some insects (e.g., mosquitoes and moths). Binary colloidal arrays consisting of exemplary large (4 and 30 ?m) and small (300 nm) silica spheres are first assembled by a scalable Langmuir-Blodgett (LB) technology in a layer-by-layer manner. After surface modification with fluorosilanes, the self-assembled hierarchical particle arrays become superhydrophobic with an apparent water contact angle (CA) larger than 150°. The throughput of the resulting superhydrophobic coatings with hierarchical structures can be significantly improved by templating the binary periodic structures of the LB-assembled colloidal arrays into UV-curable fluoropolymers by a soft lithography approach. Superhydrophobic perfluoroether acrylate hierarchical arrays with large CAs and small CA hysteresis can be faithfully replicated onto various substrates. Both experiments and theoretical calculations based on the Cassie's dewetting model demonstrate the importance of the hierarchical structure in achieving the final superhydrophobic surface states. PMID:23786830

Yang, Hongta; Dou, Xuan; Fang, Yin; Jiang, Peng

2013-09-01

361

From Liquid Crystal Polymers Containing Crown Ethers to Tapered Building Blocks Containing Crown Ethers Which Self-Assemble into Tubular Supermolecules.  

National Technical Information Service (NTIS)

Molecular recognition directed self-assembly of supramolecular architectures or noncovalent synthesis, and molecular recognition directed self-assembly of transition states or self-synthesis, are two of the most active topics of research in the area of su...

V. Percec G. Johansson

1995-01-01

362

19 CFR 10.26 - Articles assembled or processed in a beneficiary country in whole of U.S. components or...  

Code of Federal Regulations, 2013 CFR

...assembled in a beneficiary country from textile components cut to shape in the United...assembled in a beneficiary country from textile components cut to shape in the United...States. (a) No article (except a textile article, apparel article,...

2013-04-01

363

Microtubule assembly and disassembly at alkaline pH  

PubMed Central

Although it is now apparent that the intracellular pH may rise considerably above neutrality under physiological conditions, information on the effect of alkaline pH on microtubule assembly and disassembly is still quite fragmentay. We have studied the assembly/disassembly of bovine brain microtubule protein at alkaline pH in vitro. When microtubules are assembled to a new steady state at pH less than 7 and pH is then made more alkaline, they undergo a rapid disassembly to a new steady state. This disassembly is reversed by acidification. The degree of disassembly is determined largely by the pH- dependence of the critical concentration, which increases five to eight times, from pH 7 to 8. A fraction of assembly-incompetent tubulin is identified that increases with pH, but its incompetency is largely reversed with acidification. Measurements of microtubule lengths are used to indicate that disassembly occurs by uniform shortening of microtubules. A comparison of shortening by alkalinization with dilution suggests that the intrinsic rate of disassembly is accelerated by increasing pH. The capacity for initiating assembly is progressively lost with incubation at alkaline pH (although some protection is afforded by sulfhydryl-reducing agents). However, direct assembly from depolymerized mixtures is possible at least up to pH 8.3, and the steady state achieved at these alkaline pH values is stable. Such preparations are readily disassembled by cold and podophyllotoxin (PLN). Disassembly induced by PLN is also markedly enhanced at alkaline pH, suggesting a corresponding enhancement of “treadmilling.” The implications of physiological events leading to alkaline shifts of pH for microtubule assembly/disassembly are discussed, particularly in the light of recent hypotheses regarding treadmilling and its role in controlling the distribution of microtubules in vivo.

Regula, CS; Pfeiffer; Berlin, RD

1981-01-01

364

Gear box assembly  

SciTech Connect

This patent describes a gearbox assembly for a vehicle which includes a driven axle shaft extending transversely of the vehicle having wheels secured thereto: a drive gear concentric with the axle shaft nonrotatably connected to the shaft, the drive gear having an integral hub on each of opposite sides thereof, a pinion gear shiftably mounted above the drive gear having one position engaging the drive gear and shiftable laterally to disengage from the drive gear, a shift lever mounted in a position projecting upwardly from the pinion gear actuatable to shift the pinion gear, an electric motor with output shaft mounted with the output shaft paralleling the axle shaft and having a driving gear mounted thereon, a multiple gear gear train mounted so as to establish a driving connection between the driving gear and the pinion gear, and a transmission housing enclosing the driving gar, gear train, pinion gear and drive gear, the housing including sleeve portions rotatably receiving the hubs of the drive gear and thus rotatably mounting the drive gear and the axle shaft connected to the drive gear.

Harrod, L.R.; Siebern, M.R.

1989-04-25

365

Concentric tube support assembly  

DOEpatents

An assembly (45) includes a plurality of separate pie-shaped segments (72) forming a disk (70) around a central region (48) for retaining a plurality of tubes (46) in a concentrically spaced apart configuration. Each segment includes a support member (94) radially extending along an upstream face (96) of the segment and a plurality of annularly curved support arms (98) transversely attached to the support member and radially spaced apart from one another away from the central region for receiving respective upstream end portions of the tubes in arc-shaped spaces (100) between the arms. Each segment also includes a radial passageway (102) formed in the support member for receiving a fluid segment portion (106) and a plurality of annular passageways (104) formed in the support arms for receiving respective arm portions (108) of the fluid segment portion from the radial passageway and for conducting the respective arm portions into corresponding annular spaces (47) formed between the tubes retained by the disk.

Rubio, Mark F.; Glessner, John C.

2012-09-04

366

Fuel burner assembly  

SciTech Connect

A fuel burner assembly is described for providing a stable, non-pulsating flame wall proximate the outlet of a burner duct comprising: a burner duct having an upstream inlet end and a downstream outlet end, the inlet end being adapted to be connected to a source of combustion air and the outlet and being adapted to accommodate a burner flame wall proximate thereto; a sleeve member supportively disposed within the burner duct to extend along the longitudinal axis thereof; a transverse baffle member extending across the inner wall of the sleeve member intermediate the inlet and outlet ends thereof to define upstream and downstream chambers within the sleeve member between the inlet and outlet ends thereof; first air passage means in the sleeve member wall between the upstream chamber and the diversion chamber and second air passage means in the sleeve member wall between the diversion chamber and the downstream chamber; spaced fuel outlet and igniter means selectively positioned in the downstream chamber proximate the outlet end thereof to ignite with the radially inward directed combustion air to create a burner flame wall proximate the outlet end of the burner duct.

Mutchler, P.A.

1988-06-28

367

Flexible Foot Test Assembly  

SciTech Connect

A test model of the flexible foot support was constructed early in the design stages to check its reactions to applied loads. The prototype was made of SS 304 and contained four vertical plates as opposed to the fourteen Inconel 718 plates which comprise the actual structure. Due to the fact that the prototype was built before the design of the support was finalized, the plate dimensions are different from those of the actual proposed design (i.e. model plate thickness is approximately one-half that of the actual plates). See DWG. 3740.210-MC-222376 for assembly details of the test model and DWG. 3740.210-MB-222377 for plate dimensions. This stanchion will be required to not only support the load of the inner vessel of the cryostat and its contents, but it must also allow for the movement of the vessel due to thermal contraction. Assuming that each vertical plate acts as a column, then the following formula from the Manual of Steel Construction (American Institute of Steel Construction, Inc., Eigth edition, 1980) can be applied to determine whether or not such columns undergoing simultaneous axial compression and transverse loading are considered safe for the given loading. The first term is representative of the axially compressive stress, and the second term, the bending stress. If the actual compressive stress is greater than 15% of the allowable compressive stress, then there are additional considerations which must be accounted for in the bending stress term.

Kurita, C.H.; /Fermilab

1987-04-27

368

Polyphosphazene Microcapsules Fabricated through Covalent Assembly.  

PubMed

Hollow polyphosphazene microcapsules have been fabricated by the covalent layer-by-layer assembly of polydichlorophosphazene (PDCP) and hexamethylenediamine (HDA) on aminosilanized silica particles, followed by core removal in a HF/NH(4) F solution. The hollow and intact microcapsules in both wet and dry states have been characterized by transmission electron microscopy and confocal laser scanning microscopy. The chemical structure of the microcapsules has been verified by FT-IR spectroscopy. The microcapsules could be hydrolytically degraded in a phosphate buffer at biological pH. PMID:21706623

Feng, Zhiqiang; Fan, Guoqiang; Wang, Hongxia; Gao, Changyou; Shen, Jiacong

2009-03-19

369

Drive piston assembly for a valve actuator assembly  

DOEpatents

A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

Sun, Zongxuan (Troy, MI)

2010-02-23

370

Benchmark Assemblies of the Los Alamos Critical Assemblies Facility.  

National Technical Information Service (NTIS)

Several critical assemblies of precisely known materials composition and easily calculated and reproducible geometries have been constructed at the Los Alamos National Laboratory. Some of these machines, notably Jezebel, Flattop, Big Ten, and Godiva, have...

E. J. Dowdy

1985-01-01

371

NASA AMES infrared detector assemblies  

NASA Technical Reports Server (NTRS)

Silicon: Gallium infrared detector assemblies were designed, fabricated, and tested using techniques representative of those employed for hybrid arrays to determine the suitability of this candidate technology for infrared astronomical detector array applications. Both the single channel assembly and the assembly using a 32 channel CMOS multiplexer are considered. The detector material was certified to have a boron background of less than 10 to the 13th power atoms/sq cm counter doped with phosphorus. The gallium concentration is 2 x 10 to the 16th power atoms/cu cm.

1979-01-01

372

Cooling assembly for fuel cells  

DOEpatents

A cooling assembly for fuel cells having a simplified construction whereby coolant is efficiently circulated through a conduit arranged in serpentine fashion in a channel within a member of such assembly. The channel is adapted to cradle a flexible, chemically inert, conformable conduit capable of manipulation into a variety of cooling patterns without crimping or otherwise restricting of coolant flow. The conduit, when assembled with the member, conforms into intimate contact with the member for good thermal conductivity. The conduit is non-corrodible and can be constructed as a single, manifold-free, continuous coolant passage means having only one inlet and one outlet.

Kaufman, Arthur (West Orange, NJ); Werth, John (Princeton, NJ)

1990-01-01

373

RHIC Beam Position Monitor Assemblies.  

National Technical Information Service (NTIS)

Design calculations, design details, and fabrication techniques for the RHIC BPM Assemblies are discussed. The 69 mm aperture single plane detectors are 23 cm long short-circuited 50 ohm strip transmission lines subtending 80 degrees. They are mounted on ...

P. R. Cameron M. C. Grau W. A. Ryan T. J. Shea R. E. Sikora

1993-01-01

374

Shaft seal assembly and method  

NASA Technical Reports Server (NTRS)

A pressure-actuated shaft seal assembly and associated method for controlling the flow of fluid adjacent a rotatable shaft are provided. The seal assembly includes one or more seal members that can be adjusted between open and closed positions, for example, according to the rotational speed of the shaft. For example, the seal member can be configured to be adjusted according to a radial pressure differential in a fluid that varies with the rotational speed of the shaft. In addition, in the closed position, each seal member can contact a rotatable member connected to the shaft to form a seal with the rotatable member and prevent fluid from flowing through the assembly. Thus, the seal can be closed at low speeds of operation and opened at high speeds of operation, thereby reducing the heat and wear in the seal assembly while maintaining a sufficient seal during all speeds of operation.

Keba, John E. (Inventor)

2007-01-01

375

Laser alignment of large assemblies  

NASA Technical Reports Server (NTRS)

Electronically leveled laser instrument, incorporating special tiltmeter-controlled laser alignment transit, simplifies alignment of large structure. System operated from single alignment reference tower saves time and costs in assembling of structures.

Cazares, W. S.; Kern, D. D.

1979-01-01

376

Land Assembly: Problems and Techniques.  

National Technical Information Service (NTIS)

Contents: National land commission; Regional land development authorities; Private condemnation; Land purchase; Land and urban expansion; Urban renewal and new towns; Land assembly--the foreign experience; The effect of technology and design on land costs...

G. Edwards

1968-01-01

377

Nanoloom for controlling polymer assembly  

US Patent & Trademark Office Database

Systems, devices, and methods are provided for assembling polymer-forming molecular components such that highly-structured arrays of polymer strands, such as collagen fibrils, are formed without the need for cells. A polymer nanoloom is designed to control the self-assembly of monomers into fibrils and related tissue constructs including ligament, tendon, cartilage, and bone. A nanoloom system comprises a polymer printhead, a temperature controller, and a movable substrate for polymer printing. A polymer printhead contains one or more nanoreactors that can control the assembly of collagen fibrils or other polymers on a nanoscale. Methods are provided for temperature-driven, enzyme-driven, and cholesteric assembly of collagen or other polymers into two- or three-dimensional tissue constructs.

2012-06-26

378

Hear Exchange Assembly  

DOEpatents

A heat exchange assembly comprises a plurality of plates disposed in a spaced-apart arrangement, each of the plurality of plates includes a plurality of passages extending internally from a first end to a second end for directing flow of a heat transfer fluid in a first plane, a plurality of first end-piece members equaling the number of plates and a plurality of second end-piece members also equaling the number of plates, each of the first and second end-piece members including a recessed region adapted to fluidly connect and couple with the first and second ends of the plate, respectively, and further adapted to be affixed to respective adjacent first and second end-piece members in a stacked formation, and each of the first and second end-piece members further including at least one cavity for enabling entry of the heat transfer fluid into the plate, exit of the heat transfer fluid from the plate, or 180.degree. turning of the fluid within the plate to create a serpentine-like fluid flow path between points of entry and exit of the fluid, and at least two fluid conduits extending through the stacked plurality of first and second end-piece members for providing first fluid connections between the parallel fluid entry points of adjacent plates and a fluid supply inlet, and second fluid connections between the parallel fluid exit points of adjacent plates and a fluid discharge outlet so that the heat transfer fluid travels in parallel paths through each respective plate.

Lowenstein, Andrew (Princeton, NJ); Sibilia, Marc (Princeton, NJ); Miller, Jeffrey (Rocky Hill, NJ); Tonon, Thomas S. (Princeton, NJ)

2003-05-27

379

A proximity-based programmable DNA nanoscale assembly line.  

PubMed

Our ability to synthesize nanometre-scale chemical species, such as nanoparticles with desired shapes and compositions, offers the exciting prospect of generating new functional materials and devices by combining them in a controlled fashion into larger structures. Self-assembly can achieve this task efficiently, but may be subject to thermodynamic and kinetic limitations: reactants, intermediates and products may collide with each other throughout the assembly time course to produce non-target species instead of target species. An alternative approach to nanoscale assembly uses information-containing molecules such as DNA to control interactions and thereby minimize unwanted cross-talk between different components. In principle, this method should allow the stepwise and programmed construction of target products by linking individually selected nanoscale components-much as an automobile is built on an assembly line. Here we demonstrate that a nanoscale assembly line can be realized by the judicious combination of three known DNA-based modules: a DNA origami tile that provides a framework and track for the assembly process, cassettes containing three independently controlled two-state DNA machines that serve as programmable cargo-donating devices and are attached in series to the tile, and a DNA walker that can move on the track from device to device and collect cargo. As the walker traverses the pathway prescribed by the origami tile track, it sequentially encounters the three DNA devices, each of which can be independently switched between an 'ON' state, allowing its cargo to be transferred to the walker, and an 'OFF' state, in which no transfer occurs. We use three different types of gold nanoparticle species as cargo and show that the experimental system does indeed allow the controlled fabrication of the eight different products that can be obtained with three two-state devices. PMID:20463734

Gu, Hongzhou; Chao, Jie; Xiao, Shou-Jun; Seeman, Nadrian C

2010-05-13

380

Developmental self-assembly of a DNA tetrahedron.  

PubMed

Kinetically controlled isothermal growth is fundamental to biological development, yet it remains challenging to rationally design molecular systems that self-assemble isothermally into complex geometries via prescribed assembly and disassembly pathways. By exploiting the programmable chemistry of base pairing, sophisticated spatial and temporal control have been demonstrated in DNA self-assembly, but largely as separate pursuits. By integrating temporal with spatial control, here we demonstrate the "developmental" self-assembly of a DNA tetrahedron, where a prescriptive molecular program orchestrates the kinetic pathways by which DNA molecules isothermally self-assemble into a well-defined three-dimensional wireframe geometry. In this reaction, nine DNA reactants initially coexist metastably, but upon catalysis by a DNA initiator molecule, navigate 24 individually characterizable intermediate states via prescribed assembly pathways, organized both in series and in parallel, to arrive at the tetrahedral final product. In contrast to previous work on dynamic DNA nanotechnology, this developmental program coordinates growth of ringed substructures into a three-dimensional wireframe superstructure, taking a step toward the goal of kinetically controlled isothermal growth of complex three-dimensional geometries. PMID:24720462

Sadowski, John P; Calvert, Colby R; Zhang, David Yu; Pierce, Niles A; Yin, Peng

2014-04-22

381

Mitotic spindle assembly by two different pathways in vitro  

PubMed Central

We have used Xenopus egg extracts to study spindle morphogenesis in a cell-free system and have identified two pathways of spindle assembly in vitro using methods of fluorescent analogue cytochemistry. When demembranated sperm nuclei are added to egg extracts arrested in a mitotic state, individual nuclei direct the assembly of polarized microtubule arrays, which we term half-spindles; half-spindles then fuse pairwise to form bipolar spindles. In contrast, when sperm nuclei are added to extracts that are induced to enter interphase and arrested in the following mitosis, a single sperm nucleus can direct the assembly of a complete spindle. We find that microtubule arrays in vitro are strongly biased towards chromatin, but this does not depend on specific kinetochore-microtubule interactions. Indeed, although we have identified morphological and probably functional kinetochores in spindles assembled in vitro, kinetochores appear not to play an obligate role in the establishment of stable, bipolar microtubule arrays in either assembly pathway. Features of the two pathways suggest that spindle assembly involves a hierarchy of selective microtubule stabilization, involving both chromatin-microtubule interactions and antiparallel microtubule-microtubule interactions, and that fundamental molecular interactions are probably the same in both pathways. This in vitro reconstitution system should be useful for identifying the molecules regulating the generation of asymmetric microtubule arrays and for understanding spindle morphogenesis in general.

1991-01-01

382

Grids for nuclear fuel assemblies  

SciTech Connect

A spacer grid for fuel assemblies in a water reactor is provided. The grid shell is shaped so that a pressing in zircaloy can be made. Cross members in a lattice in the shell provide spacing for the fuel pins of the fuel assembly. Each fuel pin has its own cell in the lattice, and at least some of the joints between the members comprise two attachment points spaced along one of the members at a single intersection.

Nicholson, G.

1982-09-28

383

Fuel cell design and assembly  

DOEpatents

The present invention is directed to a novel bipolar cooling plate, fuel cell design and method of assembly of fuel cells. The bipolar cooling plate used in the fuel cell design and method of assembly has discrete opposite edge and means carried by the plate defining a plurality of channels extending along the surface of the plate toward the opposite edges. At least one edge of the channels terminates short of the edge of the plate defining a recess for receiving a fastener.

Myerhoff, Alfred (Greensburg, PA)

1984-01-01

384

Recombinant CLIC1 (NCC27) assembles in lipid bilayers via a pH-dependent two-state process to form chloride ion channels with identical characteristics to those observed in Chinese hamster ovary cells expressing CLIC1.  

PubMed

CLIC1 (NCC27) is an unusual, largely intracellular, ion channel that exists in both soluble and membrane-associated forms. The soluble recombinant protein can be expressed in Escherichia coli, a property that has made possible both detailed electrophysiological studies in lipid bilayers and an examination of the mechanism of membrane integration. Soluble E. coli-derived CLIC1 moves from solution into artificial bilayers and forms chloride-selective ion channels with essentially identical conductance, pharmacology, and opening and closing kinetics to those observed in CLIC1-transfected Chinese hamster ovary cells. The process of membrane integration of CLIC1 is pH-dependent. Following addition of protein to the trans solution, small conductance channels with slow kinetics (SCSK) appear in the bilayer. These SCSK modules then appear to undergo a transition to form a high conductance channel with fast kinetics. This has four times the conductance of the SCSK and fast kinetics that characterize the native channel. This suggests that the CLIC1 ion channel is likely to consist of a tetrameric assembly of subunits and indicates that despite its size and unusual properties, it is able to form a completely functional ion channel in the absence of any other ancillary proteins. PMID:11978800

Warton, Kristina; Tonini, Raffaella; Fairlie, W Douglas; Matthews, Jacqueline M; Valenzuela, Stella M; Qiu, Min Ru; Wu, Wan Man; Pankhurst, Susan; Bauskin, Asne R; Harrop, Stephen J; Campbell, Terence J; Curmi, Paul M G; Breit, Samuel N; Mazzanti, Michele

2002-07-19

385

Nanoparticle induced self-assembly  

NASA Astrophysics Data System (ADS)

Self-assembly has for the large part focused on the assembly of molecules without guidance or management from an outside source. However, self-assembly is in principle by no means limited to molecules or the nanoscale. A particularly interesting method to the self-assembly of micro- to millimetre sized components is the use of the 'magnetic hole' effect. In this method, nonmagnetic particles can be manipulated by external magnetic fields by immersing them in a dispersion of colloidal, magnetic nanoparticles, denoted ferrofluids. Nonmagnetic particles in magnetized ferrofluids are in many ways ideal model systems to test various forms of particle self-assembly and dynamics. When microspheres are confined to a monolayer between two parallel plates and subjected to static or oscillating magnetic fields they show a variety of dynamical behaviours and assemblages, depending on the frequency and direction of the external fields. A single pair of magnetic holes oscillating in a ferrofluid layer may be used to measure the viscosity of tiny volumes of the fluid. We have also observed ordering of dilute dispersions of macromolecules and nanoparticles in magnetized ferrofluids. The self-assembly at this length scale results from structural correlations between these nanostructures and ferrofluid particles rather than from the macroscopic magnetostatic effect for the magnetic holes.

Helgesen, G.; Svåsand, E.; Skjeltorp, A. T.

2008-05-01

386

Reference-assisted chromosome assembly  

PubMed Central

One of the most difficult problems in modern genomics is the assembly of full-length chromosomes using next generation sequencing (NGS) data. To address this problem, we developed “reference-assisted chromosome assembly” (RACA), an algorithm to reliably order and orient sequence scaffolds generated by NGS and assemblers into longer chromosomal fragments using comparative genome information and paired-end reads. Evaluation of results using simulated and real genome assemblies indicates that our approach can substantially improve genomes generated by a wide variety of de novo assemblers if a good reference assembly of a closely related species and outgroup genomes are available. We used RACA to reconstruct 60 Tibetan antelope (Pantholops hodgsonii) chromosome fragments from 1,434 SOAPdenovo sequence scaffolds, of which 16 chromosome fragments were homologous to complete cattle chromosomes. Experimental validation by PCR showed that predictions made by RACA are highly accurate. Our results indicate that RACA will significantly facilitate the study of chromosome evolution and genome rearrangements for the large number of genomes being sequenced by NGS that do not have a genetic or physical map.

Kim, Jaebum; Larkin, Denis M.; Cai, Qingle; Asan; Zhang, Yongfen; Ge, Ri-Li; Auvil, Loretta; Capitanu, Boris; Zhang, Guojie; Lewin, Harris A.; Ma, Jian

2013-01-01

387

Operation of the low power reactor assembly in the University of Illinois TRIGA bulk shielding facility  

Microsoft Academic Search

The Low Power Reactor Assembly (LOPRA) is a rectangular assembly of TRIGA fuel elements located in the bulk shielding facility of the Illinois Advanced TRIGA Reactor (TRIGA). The LOPRA is coupled to the TRIGA by a thermal column that extends from the TRIGA core to the bulk shielding facility. The LOPRA will be utilized for studying steady-state and transient coupling

G. P. Beck; G. Thayer

1972-01-01

388

Fluorescent coronene monoimide gels via H-bonding induced frustrated dipolar assembly.  

PubMed

Two stage self-assembly of novel coronene monoimide (CMI) based gels that results in resurfacing of monomer emission in the aggregated state is reported. This process is attributed to a frustrated head-head dipolar assembly forced by hydrogen bonding. PMID:21952511

Jain, Ankit; Rao, K Venkata; Kulkarni, Chidambar; George, Anjana; George, Subi J

2012-02-01

389

Analysis of avian communities in Lake Guri, Venezuela, using multiple assembly rule models  

Microsoft Academic Search

This study analyzed the distribution of resident, forest-interior bird species nesting on islands in Lake Guri, Venezuela using several different community assembly rule models. The models that were tested included Diamond's Assembly Rules, Size Structure, Guild Proportionality, Favored States, and Nestedness. It was determined that the species composition of the study communities was only weakly influenced by competition, but that

Kenneth Feeley

2003-01-01

390

Investigation of degradation behavior of membrane electrode assembly with polytetrafluoroethylene\\/Nafion composite membrane  

Microsoft Academic Search

The main purpose of this study is to investigate the accelerated degradation of the PTFE\\/Nafion membrane electrode assembly through open circuit voltage and relative humidity cycling. The state of a PTFE\\/Nafion membrane electrode assembly is evaluated in a fuel cell by monitoring the polarization curve, AC impedance, cyclic voltammetry, and linear sweep voltammetry data over time. The experimental results are

Ting-Chu Jao; Guo-Bin Jung; Pei-Hung Chi; Shih-Tsung Ke; Shih-Hung Chan

391

Feature-by-feature--evaluating de novo sequence assembly.  

PubMed

The whole-genome sequence assembly (WGSA) problem is among one of the most studied problems in computational biology. Despite the availability of a plethora of tools (i.e., assemblers), all claiming to have solved the WGSA problem, little has been done to systematically compare their accuracy and power. Traditional methods rely on standard metrics and read simulation: while on the one hand, metrics like N50 and number of contigs focus only on size without proportionately emphasizing the information about the correctness of the assembly, comparisons performed on simulated dataset, on the other hand, can be highly biased by the non-realistic assumptions in the underlying read generator. Recently the Feature Response Curve (FRC) method was proposed to assess the overall assembly quality and correctness: FRC transparently captures the trade-offs between contigs' quality against their sizes. Nevertheless, the relationship among the different features and their relative importance remains unknown. In particular, FRC cannot account for the correlation among the different features. We analyzed the correlation among different features in order to better describe their relationships and their importance in gauging assembly quality and correctness. In particular, using multivariate techniques like principal and independent component analysis we were able to estimate the "excess-dimensionality" of the feature space. Moreover, principal component analysis allowed us to show how poorly the acclaimed N50 metric describes the assembly quality. Applying independent component analysis we identified a subset of features that better describe the assemblers performances. We demonstrated that by focusing on a reduced set of highly informative features we can use the FRC curve to better describe and compare the performances of different assemblers. Moreover, as a by-product of our analysis, we discovered how often evaluation based on simulated data, obtained with state of the art simulators, lead to not-so-realistic results. PMID:22319599

Vezzi, Francesco; Narzisi, Giuseppe; Mishra, Bud

2012-01-01

392

Feature-by-Feature - Evaluating De Novo Sequence Assembly  

PubMed Central

The whole-genome sequence assembly (WGSA) problem is among one of the most studied problems in computational biology. Despite the availability of a plethora of tools (i.e., assemblers), all claiming to have solved the WGSA problem, little has been done to systematically compare their accuracy and power. Traditional methods rely on standard metrics and read simulation: while on the one hand, metrics like N50 and number of contigs focus only on size without proportionately emphasizing the information about the correctness of the assembly, comparisons performed on simulated dataset, on the other hand, can be highly biased by the non-realistic assumptions in the underlying read generator. Recently the Feature Response Curve (FRC) method was proposed to assess the overall assembly quality and correctness: FRC transparently captures the trade-offs between contigs' quality against their sizes. Nevertheless, the relationship among the different features and their relative importance remains unknown. In particular, FRC cannot account for the correlation among the different features. We analyzed the correlation among different features in order to better describe their relationships and their importance in gauging assembly quality and correctness. In particular, using multivariate techniques like principal and independent component analysis we were able to estimate the “excess-dimensionality” of the feature space. Moreover, principal component analysis allowed us to show how poorly the acclaimed N50 metric describes the assembly quality. Applying independent component analysis we identified a subset of features that better describe the assemblers performances. We demonstrated that by focusing on a reduced set of highly informative features we can use the FRC curve to better describe and compare the performances of different assemblers. Moreover, as a by-product of our analysis, we discovered how often evaluation based on simulated data, obtained with state of the art simulators, lead to not-so-realistic results.

Vezzi, Francesco; Narzisi, Giuseppe; Mishra, Bud

2012-01-01

393

Supramolecular hydrogen-bonding assembly of silanediols with bifunctional heterocycles.  

PubMed

X-ray crystallography showcases the distinct self-association and hydrogen-bonding patterns of organic silanediols, R2Si(OH)2, with bifunctional heterocycles for supramolecular assembly. Diffusion-ordered spectroscopy (DOSY) studies identify the dominant hydrogen-bonding patterns and structures in solution, which correlate with solid-state patterns at high concentrations. PMID:24577634

Tran, Ngon T; Wilson, Sean O; Franz, Annaliese K

2014-04-11

394

8. INTERIOR VIEW OF ASSEMBLY ROOM (REAR FACADE), UNTANKING TOWER, ...  

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

8. INTERIOR VIEW OF ASSEMBLY ROOM (REAR FACADE), UNTANKING TOWER, SHOWING PREVIOUS MODIFICATIONS (INSTALLATION OF METAL ROLL-UP DOOR, LEFT FOREGROUND). 125-TON LIFTING CRANE (TOP FOREGROUND), AND ORIGINAL FLOOR-TO-CEILING MULTI-PANE, METAL-CASED WINDOWS - Bonneville Power Administration Chehalis Substation, Untanking Tower, State Route 603, West of Interstate 5, Napavine, Lewis County, WA

395

Pneumatic Power Drive Wheel and related assembly for Turntable, with ...  

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

Pneumatic Power Drive Wheel and related assembly for Turntable, with scale. Not in use August 1994. Turntable rotated with engine and tender on balance by two persons, one on either side at ground level - East Broad Top Railroad & Coal Company, Roundhouse, State Route 994, West of U.S. Route 522, Rockhill Furnace, Huntingdon County, PA

396

Quantum assembly semantics: The fallacious lingo of occupation numbers  

NASA Astrophysics Data System (ADS)

The usual heuristic description of quantum mechanical assemblies features so-called “occupation numbers” interpreted quite literally. This essay critically compares that point of view with a more rigorous understanding of composite systems based upon a principal lesson of Einstein's paradox and Bell's inequality, viz., that it is fallacious to regard a subsystem as possessing or “occupying” any state whatever.

Park, James L.

1991-01-01

397

Accomplishments in Field Period Assembly for NCSX* This is how we did it  

SciTech Connect

The National Compact Stellarator Experiment (NCSX) was a collaborative effort between ORNL and PPPL. PPPL provided the assembly techniques with guidance from ORNL to meet design criteria. The individual vacuum vessel segments, modular coils, trim coils, and toroidal field coils components were delivered to the Field Period Assembly (FPA) crew who then would complete the component assemblies and then assemble the final three field period assemblies, each consisting of two sets of three modular coils assembled over a 120o vacuum vessel segment with the trim coils and toroidal field coils providing the outer layer. The requirements for positioning the modular coils were found to be most demanding. The assembly tolerances required for accurate positioning of the field coil windings in order to generate sufficiently accurate magnetic fields strained state of the art techniques in metrology and alignment and required constant monitoring of assembly steps with laser trackers, measurement arms, and photogrammetry. The FPA activities were being performed concurrently while engineering challenges were being resolved. For example, it was determined that high friction electrically isolated shims were needed between the modular coil interface joints and low distortion welding was required in the nose region of those joints. This took months of analysis and development yet the assembly was not significantly impacted because other assembly tasks could be performed in parallel with ongoing assembly tasks as well as tasks such as advance tooling setup preparation for the eventual welding tasks. The crew technicians developed unique, accurate time saving techniques and tooling which provided significant cost and schedule savings. Project management displayed extraordinary foresight and every opportunity to gain advanced knowledge and develop techniques was taken advantage of. Despite many risk concerns, the cost and schedule performance index was maintained nearly 1.0 during the assembly phase until project cancellation. In this paper, the assembly logic, the engineering challenges, solutions to those challenges and some of the unique and clever assembly techniques, will be presented.

Michael Viola, J. Edwards, T. Brown, L. Dudek, R. Ellis, P. Heitzenroeder, R. Strykowsky and Michael Cole

2009-09-14

398

49 CFR 572.113 - Neck assembly.  

Code of Federal Regulations, 2010 CFR

...572.113 Neck assembly. The head/neck assembly consists of the parts...78051-303 and -307, mount the head/neck assembly to the part 572 pendulum...except that the direction of the head/neck assembly is rotated around...

2009-10-01

399

49 CFR 572.113 - Neck assembly.  

Code of Federal Regulations, 2010 CFR

...572.113 Neck assembly. The head/neck assembly consists of the parts...78051-303 and -307, mount the head/neck assembly to the part 572 pendulum...except that the direction of the head/neck assembly is rotated around...

2010-10-01

400

Optimal Assembly of Psychological and Educational Tests.  

ERIC Educational Resources Information Center

Reviews optimal test-assembly literature and introduces the contributions to this special issue. Discusses four approaches to computerized test assembly: (1) heuristic-based test assembly; (2) 0-1 linear programming; (3) network-flow programming; and (4) an optimal design approach. Contains a bibliography of 90 sources on test assembly.…

van der Linden, Wim J.

1998-01-01

401

Simplified generation of all mechanical assembly sequences  

Microsoft Academic Search

Bourjault has presented a method which will generate all valid assembly sequences for the set of parts that constitute an assembly. A modification of Bourjault's method is presented which makes practical the application of this technique of assembly analysis to assemblies with greatly increased part count. The salient difference between the two methods is in the form and number of

T. De Fazio; D. E. Whitney

1987-01-01

402

Fuel assembly for a nuclear reactor  

SciTech Connect

A fuel assembly in a nuclear reactor comprises a locking mechanism that is capable of locking the fuel assembly to the core plate of a nuclear reactor to prevent inadvertent movement of the fuel assembly. The locking mechanism comprises a ratchet mechanism that allows the fuel assembly to be easily locked to the core plate but prevents unlocking except when the ratchet is disengaged.

Gjertsen, R.K.

1983-04-26

403

Electric field mediated colloidal assembly and control  

NASA Astrophysics Data System (ADS)

This dissertation presents video microscopy measurements and computer simulations of colloidal particle interactions in inhomogeneous, high-frequency AC electric fields. The interactions of particles with each other and inhomogeneous electric fields are quantified as a function of concentration, field amplitude, and frequency. Visual state diagrams show that these interactions in concentrated systems produce quasi-two dimensional microstructures including confined hard disk fluids, oriented dipolar chains, and oriented hexagonal close packed crystals. The interaction of a particle interacting with an electric field is directly measured with analyses of a single diffusing colloid within electric fields in the absence of many body effects. Concentrated systems are characterized in terms of density profiles across the electrode gap and angular pair distribution functions. An inverse Monte Carlo analysis extracted the induced dipole-induced dipole interaction from concentrated measurements. A single adjustable parameter consistently modified the induced dipole-field potential and the induced dipole-induced dipole potential to account for modification of the local electric field as the result of the local particle concentration, frequency and configuration. Confocal laser scanning microscopy (CLSM) perform sensitive measurements of internal three dimensional structure of crystals assembled in an interfacial quadrupole electrode device. Radial distributions as functions of elevation are used to characterize the equilibrium structure. A single adjustable parameter modified known potentials to match Monte Carlo simulations with experiment. The local density from experiment and simulation matched the expected density calculated from a balance of osmotic pressure and dielectrophoretic compression. Simulations qualitatively matched experimental observations of microstructure as a function of field amplitude. Programmable assembly for colloidal crystals is implemented in the quadrupole electrode device by guiding the dynamic evolution of a colloidal ensemble. A feedback method is used to control electric field mediated assembly based on real-time sensing and actuation single and multiple electrokinetic mechanisms. Sensing is achieved using particle tracking and order parameter computation to quantify the degree of order during the assembly process. A geometrical parameter for hexagonal close packing and radius of gyration are investigated as order parameters for quantifying condensation and crystallization. Colloidal crystal assembly and disassembly is actuated using electroosmosis and negative and positive dielectrophoresis (i.e. dipole-field interactions).

Juarez, Jaime Javier

404

Institutional Reports on Pacific Rim Programs. Submissions by the California Community Colleges, the California State University, and the University of California in Response to Assembly Concurrent Resolution 82 (1986). Commission Report 87-25.  

ERIC Educational Resources Information Center

Reports from the California State University, the University of California, and the California community colleges consider their roles in the Pacific Rim region. The Pacific Rim includes all lands with at least a portion of their coastlines fronting on the Pacific Ocean. Of concern are: the need for changes in program offerings and exchange…

California State Postsecondary Education Commission, Sacramento.

405

Impact Analysis and Test for the Spacer Grid Assembly of a Nuclear Fuel Assembly  

Microsoft Academic Search

A spacer grid assembly is one of the main structural components of the nuclear fuel assembly for a Pressurized light Water Reactor (PWR). The spacer grid assembly supports and aligns the fuel rods, guides the fuel assemblies past each other during a handling and, if needed, sustains lateral seismic loads. The ability of a spacer grid assembly to resist these

Kee-Nam Song; Sang-Hoon Lee; Soo-Bum Lee

2008-01-01

406

The Tile Complexity of Linear Assemblies  

Microsoft Academic Search

Self-assembly is fundamental to both biological processes and nanoscience. Key features of self-assembly are its probabilistic nature and local programmability. These features can be leveraged to design better self-assembled systems. The conventional Tile Assembly Model (TAM) developed by Winfree using Wang tiles is a powerful, Turing-universal theoretical framework which models varied self-assembly processes. A particular challenge in DNA nanoscience is

Harish Chandran; Nikhil Gopalkrishnan; John H. Reif

2009-01-01

407

Employing whole genome mapping for optimal de novo assembly of bacterial genomes  

PubMed Central

Background De novo genome assembly can be challenging due to inherent properties of the reads, even when using current state-of-the-art assembly tools based on de Bruijn graphs. Often users are not bio-informaticians and, in a black box approach, utilise assembly parameters such as contig length and N50 to generate whole genome sequences, potentially resulting in mis-assemblies. Findings Utilising several assembly tools based on de Bruijn graphs like Velvet, SPAdes and IDBA, we demonstrate that at the optimal N50, mis-assemblies do occur, even when using the multi-k-mer approaches of SPAdes and IDBA. We demonstrate that whole genome mapping can be used to identify these mis-assemblies and can guide the selection of the best k-mer size which yields the highest N50 without mis-assemblies. Conclusions We demonstrate the utility of whole genome mapping (WGM) as a tool to identify mis-assemblies and to guide k-mer selection and higher quality de novo genome assembly of bacterial genomes.

2014-01-01

408

LDRD final report: Automated planning and programming of assembly of fully 3D mechanisms  

SciTech Connect

This report describes the results of assembly planning research under the LDRD. The assembly planning problem is that of finding a sequence of assembly operations, starting from individual parts, that will result in complete assembly of a device specified as a CAD model. The automated assembly programming problem is that of automatically producing a robot program that will carry out a given assembly sequence. Given solutions to both of these problems, it is possible to automatically program a robot to assemble a mechanical device given as a CAD data file. This report describes the current state of our solutions to both of these problems, and a software system called Archimedes 2 we have constructed to automate these solutions. Because Archimedes 2 can input CAD data in several standard formats, we have been able to test it on a number of industrial assembly models more complex than any before attempted by automated assembly planning systems, some having over 100 parts. A complete path from a CAD model to an automatically generated robot program for assembling the device represented by the CAD model has also been demonstrated.

Kaufman, S.G.; Wilson, R.H.; Jones, R.E.; Calton, T.L.; Ames, A.L.

1996-11-01

409

Chiral detection of carotenoid assemblies.  

PubMed

Carotenoid assemblies were produced by aqueous dilution of ethanolic solutions. UV/VIS and CD spectroscopy revealed the formation of J- and H-types of aggregates of both right- and left-handed kinds. Simulation of UV/VIS spectra of the aggregates showed characteristic differences between the two types. 6'-Epimers of capsanthol ((all-E,3R,3'S,5'R)-beta,kappa-carotene-3,3',6'-triols) formed assemblies with increased chirality in dilute solution. While the absorption of 6'R-capsanthol giving H-type aggregate does not depend on the concentration, 6'S-capsanthol yielding J-type assembly showed concentration-dependent absorption intensity. Dilute aggregate of 6'R-capsanthol is characterized by an extremely large A value of -6,600. The transformation of J- to H-type assembly was observed in the mixtures of the epimers producing an intermediate kind of aggregate. A hypothetical structure for H-type assemblies is proposed. PMID:11466767

Zsila, F; Bikádi, Z; Deli, J; Simonyi, M

2001-08-01

410

75 FR 47523 - Assembly of the Administrative Conference; Filing of Advisory Committee Charter  

Federal Register 2010, 2011, 2012, 2013

...Conference; Filing of Advisory Committee Charter AGENCY: Administrative Conference of...States will file an advisory committee charter for the Assembly of the Administrative...necessary and in the public interest. The charter is appended to this notice. Dated:...

2010-08-06

411

iAssembler: a package for de novo assembly of Roche-454/Sanger transcriptome sequences  

PubMed Central

Background Expressed Sequence Tags (ESTs) have played significant roles in gene discovery and gene functional analysis, especially for non-model organisms. For organisms with no full genome sequences available, ESTs are normally assembled into longer consensus sequences for further downstream analysis. However current de novo EST assembly programs often generate large number of assembly errors that will negatively affect the downstream analysis. In order to generate more accurate consensus sequences from ESTs, tools are needed to reduce or eliminate errors from de novo assemblies. Results We present iAssembler, a pipeline that can assemble large-scale ESTs into consensus sequences with significantly higher accuracy than current existing assemblers. iAssembler employs MIRA and CAP3 assemblers to generate initial assemblies, followed by identifying and correcting two common types of transcriptome assembly errors: 1) ESTs from different transcripts (mainly alternatively spliced transcripts or paralogs) are incorrectly assembled into same contigs; and 2) ESTs from same transcripts fail to be assembled together. iAssembler can be used to assemble ESTs generated using the traditional Sanger method and/or the Roche-454 massive parallel pyrosequencing technology. Conclusion We compared performances of iAssembler and several other de novo EST assembly programs using both Roche-454 and Sanger EST datasets. It demonstrated that iAssembler generated significantly more accurate consensus sequences than other assembly programs.

2011-01-01

412

Rocket Engine Thrust Chamber Assembly  

NASA Technical Reports Server (NTRS)

A thrust chamber assembly for liquid fueled rocket engines and the method of making it wherein a two-piece mandrel wrapped with a silica tape saturated with a phenolic resin, the tape extending along the mandrel and covering the combustion chamber portion of the mandrel to the throat portion. The phenolic in the tape is cured and the end of the wrap is machined. The remainder of the mandrel is wrapped with a third silica tape. The resin in the third tape is cured and the assembly is machined. The entire assembly is then wrapped with a tow of graphite fibers wetted with an epoxy resin and, after the epoxy resin is cured, the graphite is machined to final dimensions.

Cornelius, Charles S. (Inventor); Counts, Richard H. (Inventor); Myers, W. Neill (Inventor); Lackey, Jeffrey D. (Inventor); Peters, Warren (Inventor); Shadoan, Michael D. (Inventor); Sparks, David L. (Inventor); Lawrence, Timothy W. (Inventor)

2001-01-01

413

Abrasive swivel assembly and method  

DOEpatents

An abrasive swivel assembly for providing a rotating, particle-laden fluid stream and, ultimately, a rotating particle-laden fluid jet is disclosed herein. This assembly includes a tubular arrangement for providing a particle-free stream of fluid, a swivel assembly for rotating a section of the tubular arrangement, and a tubular end section for introducing solid particles into the particle-free fluid stream at a point along the rotating tubular section, whereby to produce a particle-laden fluid stream. This last-mentioned stream can then be used in combination with a cooperating nozzle arrangement for providing a rotating particle-laden fluid jet. In an actual working embodiment, the fluid stream is of sufficiently high pressure so that the abrasive jet can be used as a cutting jet.

Hashish, Mohamed (Kent, WA); Marvin, Mark (Tacoma, WA)

1990-01-01

414

D0 Silicon Upgrade: Ladder Assembly Sequences  

SciTech Connect

This is an abridged version of the assembly sequence described by the DO assembly subgroup of Cooper, Hrycyk, Kowalski, Rapidis, and Ratzmann. This primarily is used to indicate major steps during the sequence and to list fixturing requirements. Assembly - (1) Place support rails in (1) 3 Chip Ladder Construction fixture. The two rails get held under vacuum. (2) Apply adhesive to the region where contact will be made with the beryllium substrates. (3) Place underside beryllium pieces (active and dummy ends) into the (1) 3 Chip Ladder Construction fixture. These pieces get placed in the fixture against the appropriate pins to mimic final positioning in the bulkhead. Apply vacuum to the beryllium pieces. Allow to cure? (4) Align silicon in (1) 3 Chip Ladder Construction fixture. Reference features on the fixture will be parameterized. Holes in the fixture near the silicon center line will be targeted to set the silicon axis relative to the beryllium slot edge. Z positioning of the detectors will be achieved by shimming between the detectors and butting up the end of the silicon against the fixture. (5) Remove silicon detectors and apply adhesive to the rails and upper surfaces of the beryllium. (6) Replace silicon and check final position of the detectors. (7) Release vacuum on the rails so they cure in a stress-free state. Allow adhesive to cure. (8) Apply adhesive and align HDI to the silicon using (2) 3 Chip HDI Gluing fixture. The HDI will have tabs which are held by the fixture for location relative to the detectors. Allow adhesive to cure. (9) Move ladder to (3) 3 Chip Wirebonding Fixture. Transfer fixture to the wirebonder and bond chip-silicon and silicon-silicon.

Ratzmann, Paul; /Fermilab

1994-08-17

415

The Archimedes 2 mechanical assembly planning system  

SciTech Connect

We describe the implementation and performance of Archimedes 2, an integrated mechanical assembly planning system. Archimedes 2 includes two planners, two assembly sequence animation facilities, and an associated robotic workcell. Both planners use full 3 dimensional data. A rudimentary translator from high level assembly plans to control code for the robotic workcell has also been implemented. We can translate data from a commercial CAD system into input data for the system, which has allowed us to plan assembly sequences for many industrial assemblies. Archimedes 2 has been used to plan sequences for assemblies consisting of 5 to 109 parts. We have also successfully taken a CAD model of an assembly, produced an optimized assembly sequence for it, and translated the plan into robot code, which successfully assembles the device specified in the model.

Kaufman, S.G.; Wilson, R.H.; Jones, R.E.; Calton, T.L.; Ames, A.L.

1996-03-01

416

Self-assembling amphiphilic peptides.  

PubMed

The self-assembly of several classes of amphiphilic peptides is reviewed, and selected applications are discussed. We discuss recent work on the self-assembly of lipopeptides, surfactant-like peptides and amyloid peptides derived from the amyloid-? peptide. The influence of environmental variables such as pH and temperature on aggregate nanostructure is discussed. Enzyme-induced remodelling due to peptide cleavage and nanostructure control through photocleavage or photo-cross-linking are also considered. Lastly, selected applications of amphiphilic peptides in biomedicine and materials science are outlined. © 2014 The Authors. Journal of Peptide Science published by European Peptide Society and John Wiley & Sons, Ltd. PMID:24729276

Dehsorkhi, Ashkan; Castelletto, Valeria; Hamley, Ian W

2014-07-01

417

Magnetically suspended reaction wheel assembly  

NASA Technical Reports Server (NTRS)

The magnetically suspended reaction wheel assembly (MSRWA) is the product of a development effort funded by the Air Force Materials Laboratory (AFML) at Wright Patterson AFB. The specific objective of the project was to establish the manufacturing processes for samarium cobalt magnets and demonstrate their use in a space application. The development was successful on both counts. The application portion of the program, which involves the magnetically suspended reaction wheel assembly, is emphasized. The requirements for the reaction wheel were based on the bias wheel requirements of the DSP satellite. The tasks included the design, fabrication, and test of the unit to the DSP program qualification requirements.

Stocking, G.

1984-01-01

418

DNA-guided nanoparticle assemblies  

DOEpatents

In some embodiments, DNA-capped nanoparticles are used to define a degree of crystalline order in assemblies thereof. In some embodiments, thermodynamically reversible and stable body-centered cubic (bcc) structures, with particles occupying <.about.10% of the unit cell, are formed. Designs and pathways amenable to the crystallization of particle assemblies are identified. In some embodiments, a plasmonic crystal is provided. In some aspects, a method for controlling the properties of particle assemblages is provided. In some embodiments a catalyst is formed from nanoparticles linked by nucleic acid sequences and forming an open crystal structure with catalytically active agents attached to the crystal on its surface or in interstices.

Gang, Oleg; Nykypanchuk, Dmytro; Maye, Mathew; van der Lelie, Daniel

2013-07-16

419

High speed rotor assembly shroud  

NASA Technical Reports Server (NTRS)

An improved rotor assembly shroud includes at least one reinforcing flange on the upper surface of the shroud. The strength provided by the reinforcing flange allows for a smaller shroud thickness resulting in a net reduction of shroud mass. The lower shroud mass reduces the centrifugal stress on the rotor assembly blade during operation. The strength provided by the reinforcing flanges also significantly reduces the centrifugal bending stress on the shroud during operation. The shroud mass may be further reduced by tapering the shroud leading and trailing edges or, for shrouds incorporating a damper, by providing a damper cavity with a lower diameter surface defining an opening therethrough.

Miller, Jeff H. (Inventor); Zheng, Xinhong J. (Inventor); Grota, Steven P. (Inventor); Phui, Khin C. (Inventor)

2006-01-01

420

Automated solar panel assembly line  

NASA Technical Reports Server (NTRS)

The initial stage of the automated solar panel assembly line program was devoted to concept development and proof of approach through simple experimental verification. In this phase, laboratory bench models were built to demonstrate and verify concepts. Following this phase was machine design and integration of the various machine elements. The third phase was machine assembly and debugging. In this phase, the various elements were operated as a unit and modifications were made as required. The final stage of development was the demonstration of the equipment in a pilot production operation.

Somberg, H.

1981-01-01

421

Self-assembled neuromorphic networks  

NASA Astrophysics Data System (ADS)

This paper details our experimental progress towards the synthesis of self-assembled nanostructures that may exhibit collective computational activity. Self assembled two dimensional networks of heterostructured quantum dots, linked by resistive and capacitive connections, can function as Boolean logic circuits, associative memory, image processors, and combinatorial optimizers. Computational or signal processing activity is elicited from simple charge interactions between the dots which act as non-linear resistors. Such circuits could be massively parallel, fault-tolerant, ultrafast, ultradense and dissipate very little power.

Bandyopadhyay, Supriyo; Menon, Latika; Kouklin, Nikolai A.; Williams, Paul F.; Ianno, Natale J.

2001-11-01

422

Double window viewing chamber assembly  

NASA Technical Reports Server (NTRS)

A viewing chamber which permits observation of a sample retained therein includes a pair of double window assemblies mounted in opposed openings in the walls thereof so that a light beam can directly enter and exit from the chamber. A flexible mounting arrangement for the outer windows of the window assemblies enables the windows to be brought into proper alignment. An electrical heating arrangement prevents fogging of the outer windows whereas desiccated air in the volume between the outer and inner windows prevents fogging of the latter.

Keller, V. W. (inventor); Owen, R. B. (inventor); Elkins, B. R. (inventor); White, W. T. (inventor)

1986-01-01

423

Self-assembled liposomal nanoparticles in photodynamic therapy  

PubMed Central

Photodynamic therapy (PDT) employs the combination of non-toxic photosensitizers (PS) together with harmless visible light of the appropriate wavelength to produce reactive oxygen species that kill unwanted cells. Because many PS are hydrophobic molecules prone to aggregation, numerous drug delivery vehicles have been tested to solubilize these molecules, render them biocompatible and enhance the ease of administration after intravenous injection. The recent rise in nanotechnology has markedly expanded the range of these nanoparticulate delivery vehicles beyond the well-established liposomes and micelles. Self-assembled nanoparticles are formed by judicious choice of monomer building blocks that spontaneously form a well-oriented 3-dimensional structure that incorporates the PS when subjected to the appropriate conditions. This self-assembly process is governed by a subtle interplay of forces on the molecular level. This review will cover the state of the art in the preparation and use of self-assembled liposomal nanoparticles within the context of PDT.

Sadasivam, Magesh; Avci, Pinar; Gupta, Gaurav K.; Lakshmanan, Shanmugamurthy; Chandran, Rakkiyappan; Huang, Ying-Ying; Kumar, Raj; Hamblin, Michael R.

2013-01-01

424

Final data report for the instrumented fuel assembly (IFA)-432  

SciTech Connect

This report presents the in-reactor data collected during the irradiation of the six-rod instrumented fuel assembly (IFA)-432 in the Halden Boiling Water Reactor (HBWR) from June 1980 through June 1981. This Pacific Northwest Laboratory (PNL)-designed assembly was one of a series of US Nuclear Regulatory Commission (NRC)-sponsored tests to obtain data for the development and verification of steady-state fuel performance computer codes. IFA-432 operated from December 1975 until June 1981, when it was removed from the reactor. Two of the rods were removed for examination, and the assembly was reinserted in December 1981 to obtain additional data. Fuel centerline temperatures, cladding elongations, internal fuel rod pressures, and local powers at thermocouple positions were monitored during the irradiation of IFA-432; and the resulting data are presented in this report.

Bradley, E.R.; Cunningham, M.E.; Lanning, D.D.

1982-06-01

425

TIGRA: a targeted iterative graph routing assembler for breakpoint assembly.  

PubMed

Recent progress in next-generation sequencing has greatly facilitated our study of genomic structural variation. Unlike single nucleotide variants and small indels, many structural variants have not been completely characterized at nucleotide resolution. Deriving the complete sequences underlying such breakpoints is crucial for not only accurate discovery, but also for the functional characterization of altered alleles. However, our current ability to determine such breakpoint sequences is limited because of challenges in aligning and assembling short reads. To address this issue, we developed a targeted iterative graph routing assembler, TIGRA, which implements a set of novel data analysis routines to achieve effective breakpoint assembly from next-generation sequencing data. In our assessment using data from the 1000 Genomes Project, TIGRA was able to accurately assemble the majority of deletion and mobile element insertion breakpoints, with a substantively better success rate and accuracy than other algorithms. TIGRA has been applied in the 1000 Genomes Project and other projects and is freely available for academic use. PMID:24307552

Chen, Ken; Chen, Lei; Fan, Xian; Wallis, John; Ding, Li; Weinstock, George

2014-02-01

426

Analysis of large space structures assembly: Man/machine assembly analysis  

NASA Technical Reports Server (NTRS)

Procedures for analyzing large space structures assembly via three primary modes: manual, remote and automated are outlined. Data bases on each of the assembly modes and a general data base on the shuttle capabilities to support structures assembly are presented. Task element times and structure assembly component costs are given to provide a basis for determining the comparative economics of assembly alternatives. The lessons learned from simulations of space structures assembly are detailed.

1983-01-01

427

Amplitude dependence of elasticity for the assembly of SiO2 powders under shear oscillation strain  

NASA Astrophysics Data System (ADS)

We experimentally report the elastic response of an assembly of SiO2 powders under a shear oscillation strain by a modified inverted torsion pendulum with a Couette-like setup. We find that the shear restoring force displayed by SiO2 assembly is of strong amplitude dependence, which is ascribed to the dynamic behavior of the stress network inside and could be used to classify the states of the SiO2 assembly, i.e., elastic solid, plastic solid, viscoelastic solid, and viscous fluid. The underlying mechanisms for different states of the SiO2 assembly are tentatively proposed.

Xiong, X. M.; Zhang, J. X.

2010-04-01

428

Three-Dimensional Self-Assembled Photonic Crystal Waveguide  

NASA Astrophysics Data System (ADS)

Photonic crystals (PCs), two- or three-dimensionally periodic, artificial, and dielectric structures, have a specific forbidden band for electromagnetic waves, referred to as photonic bandgap (PBG). The PBG is analogous to the electronic bandgap in natural crystal structures with periodic atomic arrangement. A well-defined and embedded planar, line, or point defect within the PCs causes a break in its structural periodicity, and introduces a state in the PBG for light localization. It offers various applications in integrated optics and photonics including optical filters, sharp bending light guides and very low threshold lasers. Using nanofabrication processes, PCs of the 2-D slab-type and 3-D layer-by-layer structures have been investigated widely. Alternatively, simple and low-cost self-assembled PCs with full 3-D PBG, inverse opals, have been suggested. A template with face centered cubic closed packed structure, opal, may initially be built by self-assembly of colloidal spheres, and is selectively removed after infiltrating high refractive index materials into the interstitials of spheres. In this dissertation, the optical waveguides utilizing the 3-D self-assembled PCs are discussed. The waveguides were fabricated by microfabrication technology. For high-quality colloidal silica spheres and PCs, reliable synthesis, self-assembly, and characterization techniques were developed. Its theoretical and experimental demonstrations are provided and correlated. They suggest that the self-assembled PCs with PBG are feasible for the applications in integrated optics and photonics.

Baek, Kang-Hyun

429

Dissecting ribosome assembly and transport in budding yeast.  

PubMed

Construction of the eukaryotic ribosome begins in the nucleolus and requires >300 evolutionarily conserved nonribosomal trans-acting factors, which transiently associate with preribosomal subunits at distinct assembly stages. A subset of trans-acting and transport factors passage assembled preribosomal subunits in a functionally inactive state through the nuclear pore complexes (NPC) into the cytoplasm, where they undergo final maturation before initiating translation. Here, we summarize the repertoire of tools developed in the model organism budding yeast that are spearheading the functional analyses of trans-acting factors involved in the assembly and intracellular transport of preribosomal subunits. We elaborate on different GFP-tagged ribosomal protein reporters and a pre-rRNA reporter that reliably monitors the movement of preribosomal particles from the nucleolus to cytoplasm. We discuss the powerful yeast heterokaryon assay, which can be employed to uncover shuttling trans-acting factors that need to accompany preribosomal subunits to the cytoplasm to be released prior to initiating translation. Moreover, we present two biochemical approaches, namely sucrose gradient analyses and tandem affinity purification, that are rapidly facilitating the uncovering of regulatory processes that control the compositional dynamics of trans-acting factors on maturing preribosomal particles. Altogether, these approaches when combined with traditional analytical biochemistry, targeted proteomics and structural methodologies, will contribute to the dissection of the assembly and intracellular transport of preribosomal subunits, as well as other macromolecular assemblies that influence diverse biological pathways. PMID:24857742

Altvater, Martin; Schütz, Sabina; Chang, Yiming; Panse, Vikram Govind

2014-01-01

430

Tuning of peptide assembly through force balance adjustment.  

PubMed

Controlled self-assembly of amphiphilic tripeptides into distinct nanostructures is achieved via a controlled design of the molecular architecture. The tripeptide Ac-Phe-Phe-Lys-CONH2 (FFK), hardly soluble in water, forms long amyloid-like tubular structures with the aid of ?-sheet hydrogen bonding and aromatic ?-? stacking. Substitution of phenylalanine (F) with tyrosine (Y), that is, only a subtle structural variation in adding a hydroxyl group to the phenyl ring, results in great change in molecular self-assembly behavior. When one F is substituted with Y, the resulting molecules of FYK and YFK self-assemble into long thinner fibrils with high propensity for lateral association. When both Fs are substituted with Y, the resulting YYK molecule forms spherical aggregates. Introduction of hydroxyl groups into the molecule modifies aromatic interactions and introduces hydrogen bonding. Moreover, since the driving forces for peptide self-assembly including hydrogen bonding, electrostatic repulsion, and ?-? stacking have high interdependence with each other, changes in aromatic interaction induce a Domino effect and cause a shift of force balance to a new state. This leads to significant variations in self-assembly behavior. PMID:23871602

Cao, Meiwen; Cao, Changhai; Zhang, Lijuan; Xia, Daohong; Xu, Hai

2013-10-01

431

Self-assembling holographic biosensors and biocomputers.  

SciTech Connect

We present concepts for self-assembly of diffractive optics with potential uses in biosensors and biocomputers. The simplest such optics, diffraction gratings, can potentially be made from chemically-stabilized microtubules migrating on nanopatterned tracks of the motor protein kinesin. We discuss the fabrication challenges involved in patterning sub-micron-scale structures with proteins that must be maintained in aqueous buffers to preserve their activity. A novel strategy is presented that employs dry contact printing onto glass-supported amino-silane monolayers of heterobifunctional crosslinkers, followed by solid-state reactions of these cross-linkers, to graft patterns of reactive groups onto the surface. Successive solution-phase addition of cysteine-mutant proteins and amine-reactive polyethylene glycol allows assembly of features onto the printed patterns. We present data from initial experiments showing successful micro- and nanopatterning of lines of single-cysteine mutants of kinesin interleaved with lines of polyethylene, indicating that this strategy can be employed to arrays of features with resolutions suitable for gratings.

Light, Yooli Kim; Bachand, George David (Sandia National Laboratories, Albuquerque, NM); Schoeniger, Joseph S.; Trent, Amanda M. (Sandia National Laboratories, Albuquerque, NM)

2006-05-01

432

Automated Array Assembly, Phase 2.  

National Technical Information Service (NTIS)

Tasks of scaling up the tandem junction cell (TJC) from 2 cm x 2 cm to 6.2 cm and the assembly of several modules using these large area TJC's are described. The scale-up of the TJC was based on using the existing process and doing the necessary design ac...

B. G. Carbajal

1979-01-01

433

Proactive Instructions for Furniture Assembly  

Microsoft Academic Search

Tennenhouse (1) coined the term proactive computing where humans get out of the interaction loop and may be serviced specically according to their needs and current situation. In this paper we propose a framework for proactive assembly instructions which aims to overcome limitations of today's printed and computer based instructions. By at- taching several computing devices and multiple sensors onto

Stavros Antifakos; Florian Michahelles; Bernt Schiele

2002-01-01

434

Hot Hollow Cathode Gun Assembly.  

National Technical Information Service (NTIS)

A hot hollow cathode deposition gun assembly includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, the hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on th...

J. D. Zeren

1983-01-01

435

Hot hollow cathode gun assembly  

NASA Astrophysics Data System (ADS)

A hot hollow cathode deposition gun assembly is disclosed. The device includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, the hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on the heat sink, and a shutter for selectively covering and uncovering the crucible.

Zeren, J. D.

1983-11-01

436

Rocket Engine Thrust Chamber Assembly  

NASA Technical Reports Server (NTRS)

A thrust chamber assembly for liquid fueled rocket engines and the method of making it wherein a two-piece mandrel having the configuration of an assembly having a combustion chamber portion connected to a nozzle portion through a throat portion is wrapped with a silica tape saturated with a phenolic resin, the tape extending along the mandrel and covering the combustion chamber portion of the mandrel to the throat portion. The width of the tape is positioned at an angle of 30 to 50 deg. to the axis of the mandrel such that one edge of the tape contacts the mandrel while the other edge is spaced from the mandrel. The phenolic in the tape is cured and the end of the wrap is machined to provide a frusto-conical surface extending at an angle of 15 to 30 deg. with respect to the axis of the mandrel for starting a second wrap on the mandrel to cover the throat portion. The remainder of the mandrel is wrapped with a third silica tape having its width positioned at a angle of 5 to 20 deg. from the axis of the mandrel. The resin in the third tape is cured and the assembly is machined to provide a smooth outer surface. The entire assembly is then wrapped with a tow of graphite fibers wetted with an epoxy resin and, after the epoxy resin is cured, the graphite is machined to final dimensions.

Cornelius, Charles S. (Inventor); Counts, Richard H. (Inventor); Myers, W. Neill (Inventor); Lackey, Jeffrey D. (Inventor); Peters, Warren (Inventor); Shadoan, Michael (Inventor); Sparks, David L. (Inventor); Lawrence, Timothy W. (Inventor)

2001-01-01

437

Component Assemblies and Component Runtimes  

Microsoft Academic Search

We propose a component programming language that sup- ports an integrated notion of both compile-time and run- time component. The centerpiece of this paper is the static, compile time notion of assembly, complementing our previ- ous work on the dynamic, runtime notion of cell. An assem- bly is a declarative, stateless piece of code that facilitates code combination. It oers

Yu David Liu; Ran Rinat; Scott F. Smith

438

Electromechanical assembly department manufacturing improvements  

SciTech Connect

Techniques for streamlining the processing and flow of products is an electromechanical assembly department were evaluated. Areas looked at included a paperless system for lot identification records, automated tool and fixture storage, evaluation of product transfer methods, and queue time reduction.

Voss, S.W.

1991-12-01

439

Assembly of quasicrystalline photonic heterostructures  

DOEpatents

A method and system for assembling a quasicrystalline heterostructure. A plurality of particles is provided with desirable predetermined character. The particles are suspended in a medium, and holographic optical traps are used to position the particles in a way to achieve an arrangement which provides a desired property.

Grier, David G. (New York, NY) [New York, NY; Roichman, Yael (New York, NY) [New York, NY; Man, Weining (Princeton, NJ) [Princeton, NJ; Chaikin, Paul Michael (Pennington, NJ) [Pennington, NJ; Steinhardt, Paul Joseph (Princeton, NJ) [Princeton, NJ

2011-07-19

440

The ribosomal subunit assembly line  

PubMed Central

Recent proteomic studies in Saccharomyces cerevisiae have identified nearly 200 proteins, other than the structural ribosomal proteins, that participate in the assembly of ribosomal subunits and their transport from the nucleus. In a separate line of research, proteomic studies of mature plant ribosomes have revealed considerable variability in the protein composition of individual ribosomes.

Dlakic, Mensur

2005-01-01

441

Iron cofactor assembly in plants.  

PubMed

Iron is an essential element for all photosynthetic organisms. The biological use of this transition metal is as an enzyme cofactor, predominantly in electron transfer and catalysis. The main forms of iron cofactor are, in order of decreasing abundance, iron-sulfur clusters, heme, and di-iron or mononuclear iron, with a wide functional range. In plants and algae, iron-sulfur cluster assembly pathways of bacterial origin are localized in the mitochondria and plastids, where there is a high demand for these cofactors. A third iron-sulfur cluster assembly pathway is present in the cytosol that depends on the mitochondria but not on plastid assembly proteins. The biosynthesis of heme takes place mainly in the plastids. The importance of iron-sulfur cofactors beyond photosynthesis and respiration has become evident with recent discoveries of novel iron-sulfur proteins involved in epigenetics and DNA metabolism. In addition, increased understanding of intracellular iron trafficking is opening up research into how iron is distributed between iron cofactor assembly pathways and how this distribution is regulated. PMID:24498975

Balk, Janneke; Schaedler, Theresia A

2014-04-29

442

J-2 Engine Assembly Line  

NASA Technical Reports Server (NTRS)

J-2 engines for the Saturn IB/Saturn V launch vehicles are lined up in the assembly area at Rocketdyne's manufacturing plant in Canoga Park, California. Five J-2 engines provided more than 1,000,000 pounds of thrust to accelerate the second stage toward a Moon trajectory.

1963-01-01

443

Flanged major modular assembly jig  

NASA Technical Reports Server (NTRS)

Weldless methods and means are described for securing flanges to the projecting ends of an unmachined box beam framework in such a manner that the flanged structure may be reused without modification. And one framework may be readily assembled to another by simply matching the flanges together and passing connecting members between performed holes in the structures.

Gilman, M. M. (inventor)

1976-01-01

444

Corner-cutting mining assembly  

DOEpatents

A mining assembly includes a primary rotary cutter mounted on one end of a support shaft and four secondary rotary cutters carried on the same support shaft and positioned behind the primary cutters for cutting corners in the hole cut by the latter.

Bradley, John A. (San Antonio, TX)

1983-01-01

445

Fuel assembly supporting structure. [PWR  

Microsoft Academic Search

For use in forming the core of a pressurized-water reactor, a fuel assembly supporting structure for holding a bundle of interspaced fuel rods, is formed by interspaced end pieces having holes in which the end portions of control rod guide tubes are inserted, fuel rod spacer grids being positioned by these guide tubes between the end pieces. The end pieces

F. W. Aisch; H. P. Fuchs; D. Knoedler; A. Steinke; J. Steven

1976-01-01

446

Simulated nuclear reactor fuel assembly  

DOEpatents

An apparatus for electrically simulating a nuclear reactor fuel assembly. It includes a heater assembly having a top end and a bottom end and a plurality of concentric heater tubes having electrical circuitry connected to a power source, and radially spaced from each other. An outer target tube and an inner target tube is concentric with the heater tubes and with each other, and the outer target tube surrounds and is radially spaced from the heater tubes. The inner target tube is surrounded by and radially spaced from the heater tubes and outer target tube. The top of the assembly is generally open to allow for the electrical power connection to the heater tubes, and the bottom of the assembly includes means for completing the electrical circuitry in the heater tubes to provide electrical resistance heating to simulate the power profile in a nuclear reactor. The embedded conductor elements in each heater tube is split into two halves for a substantial portion of its length and provided with electrical isolation such that each half of the conductor is joined at one end and is not joined at the other end.

Berta, Victor T. (Idaho Falls, ID)

1993-01-01

447

Fin Assembly for a Vehicle.  

National Technical Information Service (NTIS)

A fin assembly for effecting guidance of a vehicle through a fluid medium includes an electromagnet fixed in a portion of the vehicle, and a rigid shaft fixed to a hull portion of the vehicle and extending outwardly therefrom and in alignment with the ele...

C. P. Cho S. J. Olson

1996-01-01

448

Simulating the atomic assembly of gallium arsenide  

NASA Astrophysics Data System (ADS)

A molecular dynamics (MD) atomistic modeling and simulation approach was used to study the assembly mechanisms of homoepitaxial GaAs vapor deposition as a function of temperature and flux composition. This requires interatomic potentials that are able to reasonably predict the structures and energies of small clusters, bulk crystal lattices, and surface binding. The majority of the literature potentials could not be used in the MD simulation environment. However, the Tersoff and Stillinger-Weber (SW) potential formats could be utilized and their parametrizations were systematically evaluated. Although the Tersoff potential had very good bulk and molecular arsenic properties, the potential could not be used to study vapor deposition because it had an unphysically high As2 desorption probability over a wide range of surface temperatures. The SW potential modeled the zinc blende GaAs structure quite well; however, bonding environments with As-As and Ga-Ga interactions were poorly modeled. This limited the application of the SW potential to the study of the low-temperature atomic assembly of GaAs thin films with an equiatomic vapor. None of the compound semiconductor potentials available in literature correctly predicted the experimentally-observed surface reconstructions. A simple method for accounting for the electron occupancies of dangling bonds was proposed and was successfully used to investigate the energetics of various atomic-scale structures on the GaAs (001) surface. An analytic, bond-order potential (BOP) was proposed that improved upon many of the shortcomings of the previous potentials. The potential was derived from a tight-binding description of bonding in a manner that addresses the valence-dependent character of heteroatomic primary and secondary bonding. The structural and binding energy trends predicted by the BOP were found to match experimental observations and ab initio calculations. The homoepitaxial assembly of atomic gallium and molecular As2 on a (001) GaAs surface was also shown to phenomenologically reproduce experimental trends. The initial atomic assembly interaction dynamics were studied on gallium-terminated and arsenic-terminated surfaces. A number of intermediate binding states were directly observed during the surface diffusion of arsenic dimers on the gallium-terminated surface. Desorption, rather than diffusion, was the dominant mechanism on the arsenic-terminated surface.

Murdick, Dewey Andrew

449

Nuclear mass inventory, photon dose rate and thermal decay heat of spent research reactor fuel assemblies  

SciTech Connect

This document has been prepared to assist research reactor operators possessing spent fuel containing enriched uranium of United States origin to prepare part of the documentation necessary to ship this fuel to the United States. Data are included on the nuclear mass inventory, photon dose rate, and thermal decay heat of spent research reactor fuel assemblies. Isotopic masses of U, Np, Pu and Am that are present in spent research reactor fuel are estimated for MTR, TRIGA and DIDO-type fuel assembly types. The isotopic masses of each fuel assembly type are given as functions of U-235 burnup in the spent fuel, and of initial U-235 enrichment and U-235 mass in the fuel assembly. Photon dose rates of spent MTR, TRIGA and DIDO-type fuel assemblies are estimated for fuel assemblies with up to 80% U-235 burnup and specific power densities between 0.089 and 2.857 MW/kg[sup 235]U, and for fission product decay times of up to 20 years. Thermal decay heat loads are estimated for spent fuel based upon the fuel assembly irradiation history (average assembly power vs. elapsed time) and the spent fuel cooling time.

Pond, R.B.; Matos, J.E.

1996-12-31

450

Reactivity control assembly for nuclear reactor. [LMFBR  

DOEpatents

This invention, which resulted from a contact with the United States Department of Energy, relates to a control mechanism for a nuclear reactor and, more particularly, to an assembly for selectively shifting different numbers of reactivity modifying rods into and out of the core of a nuclear reactor. It has been proposed heretofore to control the reactivity of a breeder reactor by varying the depth of insertion of control rods (e.g., rods containing a fertile material such as ThO/sub 2/) in the core of the reactor, thereby varying the amount of neutron-thermalizing coolant and the amount of neutron-capturing material in the core. This invention relates to a mechanism which can advantageously be used in this type of reactor control system.

Bollinger, L.R.

1982-03-17

451

Timelapse: Webb's Ambient Optical Assembly Stand  

NASA Video Gallery

The clean room at NASA's Goddard Space Flight Center in Greenbelt, Md., has received a giant structural steel frame called "AOAS," the Ambient Optical Assembly Stand that will be used to assemble t...

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