Sample records for nanoparticulate ptru direct

  1. Electrooxidation of methanol and formic acid on PtRu and PtAu for direct liquid fuel cells

    Microsoft Academic Search

    Jong-Ho Choi; Kyoung-Jin Jeong; Yujung Dong; Jonghee Han; Tae-Hoon Lim; Jae-Suk Lee; Yung-Eun Sung

    2006-01-01

    The use of a PtAu catalyst as an anode catalyst for the oxidation of formic acid in direct formic acid fuel cells is described. Catalytic activities of PtAu and PtRu anodes were studied using a linear sweep voltammetry technique in a single cell configuration. PtAu showed a lower on-set potential and a larger current density than that of PtRu in

  2. The effect of catalyst support on the performance of PtRu in direct borohydride fuel cell anodes

    Microsoft Academic Search

    Vincent W. S. Lam; Akram Alfantazi; El?d L. Gyenge

    2009-01-01

    A comparative investigation of direct borohydride fuel cell polarization behavior (DBFC) was carried out with respect to the\\u000a effect of unsupported and supported PtRu anode catalysts using as supports both Vulcan XC-72R and graphite felt (GF). The\\u000a Vulcan XC-72R-supported catalyst alleviated mass-transfer-related problems associated with hydrogen generation from borohydride\\u000a hydrolysis taking place mainly on the Ru sites. However, the most

  3. The Mechanism of Direct Formic Acid Fuel Cell Using Pd, Pt and Pt-Ru

    NASA Astrophysics Data System (ADS)

    Kamiya, Nobuyuki; Liu, Yan; Mitsushima, Shigenori; Ota, Ken-Ichiro; Tsutsumi, Yasuyuki; Ogawa, Naoya; Kon, Norihiro; Eguchi, Mika

    The electro-oxidation of formic acid, 2-propanol and methanol on Pd black, Pd/C, Pt-Ru/C and Pt/C has been investigated to clear the reaction mechanism. It was suggested that the formic acid is dehydrogenated on Pd surface and the hydrogen is occluded in the Pd lattice. Thus obtained hydrogen acts like pure hydrogen supplied from the outside and the cell performance of the direct formic acid fuel cell showed as high as that of a hydrogen-oxygen fuel cell. 2-propanol did not show such dehydrogenation reaction on Pd catalyst. Platinum and Pt-Ru accelerated the oxidation of C-OH of 2-propanol and methanol. Slow scan voltammogram (SSV) and chronoamperometry measurements showed that the activity of formic acid oxidation increased in the following order: Pd black > Pd 30wt.%/C > Pt50wt.%/C > 27wt.%Pt-13wt.%Ru/C. A large oxidation current for formic acid was found at a low overpotential on the palladium electrocatalysts. These results indicate that formic acid is mainly oxidized through a dehydrogenation reaction. For the oxidation of 2-propanol and methanol, palladium was not effective, and 27wt.%Pt-13wt.%Ru/C showed the best oxidation activity.

  4. Pt-Ru supported on double-walled carbon nanotubes as high-performance anode catalysts for direct methanol fuel cells.

    PubMed

    Li, Wenzhen; Wang, Xin; Chen, Zhongwei; Waje, Mahesh; Yan, Yushan

    2006-08-10

    Pt-Ru supported on carbon nanotubes (CNTs) (single-walled nanotubes, double-walled nanotubes (DWNTs), and multi-walled nanotubes) catalysts are prepared by an ethylene glycol reduction method. Pt-Ru nanoparticles with a diameter of 2-3 nm and narrow particle size distributions are uniformly deposited onto the CNTs. A simple and fast filtration method followed by a hot-press film transfer is employed to prepare the anode catalyst layer on a Nafion membrane. The Pt-Ru/DWNTs catalyst shows the highest specific activity for methanol oxidation reaction in rotating disk electrode experiments and the highest performance as an anode catalyst in direct methanol fuel cell (DMFC) single cell tests. The DMFC single cell with Pt-Ru/DWNTs (50 wt %, 0.34 mg Pt-Ru/cm(2)) produces a 68% enhancement of power density, and at the same time, an 83% reduction of Pt-Ru electrode loading when compared to Pt-Ru/C (40 wt %, 2.0 mg Pt-Ru/cm(2)). PMID:16884255

  5. Diamond nanoparticles as a support for Pt and PtRu catalysts for direct methanol fuel cells.

    PubMed

    La-Torre-Riveros, Lyda; Guzman-Blas, Rolando; Méndez-Torres, Adrián E; Prelas, Mark; Tryk, Donald A; Cabrera, Carlos R

    2012-02-01

    Diamond in nanoparticle form is a promising material that can be used as a robust and chemically stable catalyst support in fuel cells. It has been studied and characterized physically and electrochemically, in its thin film and powder forms, as reported in the literature. In the present work, the electrochemical properties of undoped and boron-doped diamond nanoparticle electrodes, fabricated using the ink-paste method, were investigated. Methanol oxidation experiments were carried out in both half-cell and full fuel cell modes. Platinum and ruthenium nanoparticles were chemically deposited on undoped and boron doped diamond nanoparticles through the use of NaBH(4) as reducing agent and sodium dodecyl benzene sulfonate (SDBS) as a surfactant. Before and after the reduction process, samples were characterized by electron microscopy and spectroscopic techniques. The ink-paste method was also used to prepare the membrane electrode assembly with Pt and Pt-Ru modified undoped and boron-doped diamond nanoparticle catalytic systems, to perform the electrochemical experiments in a direct methanol fuel cell system. The results obtained demonstrate that diamond supported catalyst nanomaterials are promising for methanol fuel cells. PMID:22270177

  6. Monodisperse PtRu Nanoalloy on Carbon as a High-Performance DMFC Catalyst

    E-print Network

    Kwak, Juhyoun

    and Technology, Daejeon 305-701, Korea, and Department of Chemistry and Center for Electro- and Photo 2, 2006 The direct methanol fuel cell (DMFC) is a promising future energy technology alternative, reliable preparation method for monodisperse, phase-pure PtRu colloidal nano- alloy with a narrow size

  7. Effect of the structural characteristics of binary Pt-Ru and ternary Pt-Ru-M fuel cell catalysts on the activity of ethanol electrooxidation in acid medium.

    PubMed

    Antolini, Ermete

    2013-06-01

    In view of their possible use as anode materials in acid direct ethanol fuel cells, the electrocatalytic activity of Pt-Ru and Pt-Ru-M catalysts for ethanol oxidation has been investigated. This minireview examines the effects of the structural characteristics of Pt-Ru, such as the degree of alloying and Ru oxidation state, on the electrocatalytic activity for ethanol oxidation. PMID:23650220

  8. One-pot synthesis of heterostructured Pt-Ru nanocrystals for catalytic formic acid oxidation.

    PubMed

    Lu, Yizhong; Chen, Wei

    2011-03-01

    We demonstrate the synthesis of monodisperse, heterostructured Pt-Ru nanocrystals with a novel core-shell structure by a one-step method. The Pt-Ru nanocrystals show excellent electrocatalytic activity towards formic acid oxidation. Such core-shell structured Pt-Ru nanocrystals are potential candidates as anode catalysts in fuel cells. PMID:21225027

  9. PtRu overlayers on Au nanoparticles for methanol electro-oxidation

    Microsoft Academic Search

    Kug-Seung Lee; In-Su Park; Hee-Young Park; Tae-Yeol Jeon; Yung-Eun Sung

    2009-01-01

    PtRu overlayer structures were deposited on the surface of carbon-supported Au nanoparticles with atomic-scale thicknesses and their activity for methanol electro-oxidation was examined. The results of transmission electron microscopy, X-ray diffraction, and cyclic voltammetry demonstrated that the PtRu deposited uniformly on Au nanoparticles. The peak potential in CO stripping analysis shifted to higher potentials with decreasing amounts of PtRu, indicating

  10. Oxygen adsorption on Pt/Ru(0001) layers

    NASA Astrophysics Data System (ADS)

    Jakob, Peter; Schlapka, Andreas; Gazdzicki, Pawel

    2011-06-01

    Chemical properties of epitaxially grown bimetallic layers may deviate substantially from the behavior of their constituents. Strain in conjunction with electronic effects due to the nearby interface represent the dominant contribution to this modification. One of the simplest surface processes to characterize reactivity of these substrates is the dissociative adsorption of an incoming homo-nuclear diatomic molecule. In this study, the adsorption of O2 on various epitaxially grown Pt films on Ru(0001) has been investigated using infrared absorption spectroscopy and thermal desorption spectroscopy. Pt/Ru(0001) has been chosen as a model system to analyze the individual influences of lateral strain and of the residual substrate interaction on the energetics of a dissociative adsorption system. It is found that adsorption and dissociative sticking depends dramatically on Pt film thickness. Even though oxygen adsorption proceeds in a straightforward manner on Pt(111) and Ru(0001), molecular chemisorption of oxygen on Pt/Ru(0001) is entirely suppressed for the Pt/Ru(0001) monolayer. For two Pt layers chemisorbed molecular oxygen on Pt terraces is produced, albeit at a very slow rate; however, no (thermally induced) dissociation occurs. Only for Pt layer thicknesses N_{Pt} ? 3 sticking gradually speeds up and annealing leads to dissociation of O2, thereby approaching the behavior for oxygen adsorption on genuine Pt(111). For Pt monolayer films a novel state of chemisorbed O2, most likely located at step edges of Pt monolayer islands is identified. This state is readily populated which precludes an activation barrier towards adsorption, in contrast to adsorption on terrace sites of the Pt/Ru(0001) monolayer.

  11. Nanoparticulate drug delivery platforms for advancing bone infection therapies

    PubMed Central

    Uskokovi?, Vuk; Desai, Tejal A

    2015-01-01

    Introduction The ongoing surge of resistance of bacterial pathogens to antibiotic therapies and the consistently aging median member of the human race signal an impending increase in the incidence of chronic bone infection. Nanotechnological platforms for local and sustained delivery of therapeutics hold the greatest potential for providing minimally invasive and maximally regenerative therapies for this rare but persistent condition. Areas covered Shortcomings of the clinically available treatment options, including poly(methyl methacrylate) beads and calcium sulfate cements, are discussed and their transcending using calcium-phosphate/polymeric nanoparticulate composites is foreseen. Bone is a composite wherein the weakness of each component alone is compensated for by the strength of its complement and an ideal bone substitute should be fundamentally the same. Expert opinion Discrepancy between in vitro and in vivo bioactivity assessments is highlighted, alongside the inherent imperfectness of the former. Challenges entailing the cross-disciplinary nature of engineering a new generation of drug delivery vehicles are delineated and it is concluded that the future for the nanoparticulate therapeutic carriers belongs to multifunctional, synergistic and theranostic composites capable of simultaneously targeting, monitoring and treating internal organismic disturbances in a smart, feedback fashion and in direct response to the demands of the local environment. PMID:25109804

  12. PtRu nanoparticles supported on nitrogen-doped polyhedral mesoporous carbons as electrocatalyst for methanol oxidation.

    PubMed

    Zhang, Yunsong; Zhu, Rong; Cui, Ying; Zhong, Jindi; Zhang, Xiaohua; Chen, Jinhua

    2014-04-01

    Nitrogen-doped mesoporous carbons (NMPCs) with well-developed polyhedral morphology were prepared by direct carbonization of zeolitic imidazolate framework-8 (ZIF-8) nanopolyhedrons. The fantastic structural characteristics of NMPCs such as ultrahigh BET surface area (1960 m(2) g(-1)), large pore volume (1.16 cm(3) g(-1)), and nitrogen doping make it an excellent catalyst support. PtRu nanoparticles (with a size of approximately 1.9 nm) were homogeneously supported on NMPCs by microwave-assisted reduction in ethylene glycol, and the obtained PtRu/NMPCs catalyst shows a significantly higher electrocatalytic activity and stability for methanol oxidation than the typical commercial PtRu/C (E-TEK) catalyst. PMID:24594620

  13. Schottky barrier height behavior of Pt-Ru alloy contacts on single-crystal n-ZnO

    SciTech Connect

    Nagata, T.; Haemori, M.; Hayakawa, R.; Yoshitake, M.; Chikyow, T. [Advanced Electronic Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Volk, J. [Research Institute for Technical Physics and Materials Science, H-1121 Budapest, Konkoly Thege Miklos ut 29-33 (Hungary); Yamashita, Y. [Advanced Electronic Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); NIMS Beamline Station at SPring-8, National Institute for Materials Science, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Yoshikawa, H.; Ueda, S.; Kobayashi, K. [NIMS Beamline Station at SPring-8, National Institute for Materials Science, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

    2010-05-15

    We investigated the Schottky barrier height (SBH) behavior of binary alloy Schottky contacts on n-type zinc oxide (n-ZnO) single crystals. Pt-Ru alloy electrodes were deposited on the Zn-polar and O-polar faces of ZnO substrates by combinatorial ion-beam deposition under identical conditions. The crystal structures of the Pt-Ru alloy film changed from the Pt phase (cubic structure) to the Ru phase (hexagonal structure) in the Pt-Ru alloy phase diagram with decreasing Pt content. The SBH, determined from current-voltage measurements, decreased with decreasing Pt content, indicating that the SBH behavior also followed the Pt-Ru alloy phase diagram. The alloy electrodes on the Zn-polar face showed better Schottky properties than those on the O-polar face. Hard x-ray photoelectron spectroscopy revealed a difference in the interface oxidization of the Pt-Ru alloy: the interface of the O-polar face and Pt-Ru mixed phase with poor crystallinity had a more oxidized layer than that of the Zn-polar face. As a result of this oxidization, the O-polar face, Pt-Ru mixed, and Ru phases showed poor Schottky properties.

  14. Extracellular stability of nanoparticulate drug carriers.

    PubMed

    Liu, Karen C; Yeo, Yoon

    2014-01-01

    Nanoparticulate (NP) drug carrier systems are attractive vehicles for selective drug delivery to solid tumors. Ideally, NPs should evade clearance by the reticuloendothelial system while maintaining the ability to interact with tumor cells and facilitate cellular uptake. Great effort has been made to fulfill these design criteria, yielding various types of functionalized NPs. Another important consideration in NP design is the physical and functional stability during circulation, which, if ignored, can significantly undermine the promise of intelligently designed NP drug carriers. This commentary reviews several NP examples with stability issues and their consequences, ending in a discussion of experimental methods for reliable prediction of NP stability. PMID:24214175

  15. Carbon Support Effects on Bimetallic Pt-Ru Nanoparticles Formed from Molecular Precursors

    E-print Network

    Frenkel, Anatoly

    limit in the binary phase diagram.8 Solids with a PtRu5 composition are hcp in structure (although on this latter support phase. Introduction Nanometer-sized metal particles are of interest, in part due alloy cata- lysts, since the cluster predetermines the proper stoichi- ometry of the metal atoms.6

  16. Dielectrophoretic isolation and detection of cfc-DNA nanoparticulate biomarkers and virus from blood.

    PubMed

    Sonnenberg, Avery; Marciniak, Jennifer Y; McCanna, James; Krishnan, Rajaram; Rassenti, Laura; Kipps, Thomas J; Heller, Michael J

    2013-04-01

    Dielectrophoretic (DEP) microarray devices allow important cellular nanoparticulate biomarkers and virus to be rapidly isolated, concentrated, and detected directly from clinical and biological samples. A variety of submicron nanoparticulate entities including cell free circulating (cfc) DNA, mitochondria, and virus can be isolated into DEP high-field areas on microelectrodes, while blood cells and other micron-size entities become isolated into DEP low-field areas between the microelectrodes. The nanoparticulate entities are held in the DEP high-field areas while cells are washed away along with proteins and other small molecules that are not affected by the DEP electric fields. DEP carried out on 20 ?L of whole blood obtained from chronic lymphocytic leukemia patients showed a considerable amount of SYBR Green stained DNA fluorescent material concentrated in the DEP high-field regions. Whole blood obtained from healthy individuals showed little or no fluorescent DNA materials in the DEP high-field regions. Fluorescent T7 bacteriophage virus could be isolated directly from blood samples, and fluorescently stained mitochondria could be isolated from biological buffer samples. Using newer DEP microarray devices, high-molecular-weight DNA could be isolated from serum and detected at levels as low as 8-16 ng/mL. PMID:23436471

  17. Nanostructured supported Pt, Ru and PtRu catalysts for oxidation of methane into synthesis-gas

    Microsoft Academic Search

    S. A. Tungatarova; K. Dossumov; T. S. Baizhumanova; N. M. Popova

    2010-01-01

    Mono- and bimetallic Pt-, Ru- and Pt-Ru catalysts with various Pt to Ru ratio for process of selective catalytic oxidation of methane to synthesis-gas at short contact time are developed. Precious metals were supported on alumina which was modified by cerium to enhance dispersion over carrier. Pt-Ru\\/2%Ce\\/(?+?)-Al2O3, reduced by H2 at 1023K, presents a mixture of nano-particles of Pt0 (7.5–15.0nm),

  18. Intratumoral Drug Delivery with Nanoparticulate Carriers

    PubMed Central

    Holback, Hillary

    2011-01-01

    Stiff extracellular matrix, elevated interstitial fluid pressure, and the affinity for the tumor cells in the peripheral region of a solid tumor mass have long been recognized as significant barriers to diffusion of small-molecular-weight drugs and antibodies. However, their impacts on nanoparticle-based drug delivery have begun to receive due attention only recently. This article reviews biological features of many solid tumors that influence transport of drugs and nanoparticles and properties of nanoparticles relevant to their intratumoral transport, studied in various tumor models. We also discuss several experimental approaches employed to date for enhancement of intratumoral nanoparticle penetration. The impact of nanoparticle distribution on the effectiveness of chemotherapy remains to be investigated and should be considered in the design of new nanoparticulate drug carriers. PMID:21213021

  19. Carbon nanotubes embedded with PtRu nanoparticles as methanol fuel cell electrocatalysts

    NASA Astrophysics Data System (ADS)

    Hsieh, Chien-Te; Lin, Jia-Yi; Yang, Shu-Ying

    2009-01-01

    In this study, we investigate the influence of Pt:Ru atomic ratio on the electrochemical activity of PtRu/carbon nanotube (CNT) catalysts in the electrooxidation of methanol. Bimetallic PtRu alloy nanoparticles were embedded onto the CNTs by chemical impregnation, followed by the refluxing of ethylene glycol. Four types of catalysts, namely Pt 100Ru 0, Pt 75Ru 25, Pt 50Ru 50, and Pt 25Ru 75, were synthesized for the investigation of the compositional effect. The crystalline size of PtRu nanocatalysts generally decreased with the Ru atomic ratio, i.e., from 4.34 to 2.77 nm. The measurement of electrooxidation of methanol was carried out in 1 M H 2SO 4 electrolyte containing 0.5 M CH 3OH with PtRu/CNT, catalysts using cyclic voltammetry (CV) and AC electrochemical impedance spectroscopy (EIS). CV analysis revealed that the Pt 50Ru 50/CNT electrode had the highest electrochemical activity, owing to its lower onset potential and higher ratio of the forward to reverse anodic peak current. EIS combined with equivalent circuit reflected that after cycling, Pt 50Ru 50/CNT electrode has not only a much lower charge-transfer resistance, but also higher capacitance than Pt 100Ru 0/CNT. This enhancement of electrochemical activity can be ascribed to the presence of Pt-Ru atomic pair sites in the bimetallic alloys, which play an important role in regenerating the inactive Pt-CO ads sites, according to the bifunctional theory.

  20. Highly alloyed PtRu nanoparticles confined in porous carbon structure as a durable electrocatalyst for methanol oxidation.

    PubMed

    Yang, Chunzhen; Zhou, Ming; Gao, Liang

    2014-11-12

    The state-of-the-art carbon-supported PtRu catalysts are widely used as the anode catalysts in polymer electrolyte fuel cells (PEMFCs) but suffer from instability issues. Severe ruthenium dissolution occurring at potentials higher than 0.5 V vs NHE would result in a loss of catalytic activity of PtRu hence a worse performance of the fuel cell. In this work, we report an ultrastable PtRu electrocatalyst for methanol oxidation by confining highly alloyed PtRu nanoparticles in a hierarchical porous carbon structure. The structural characteristics, e.g., the surface composition and the morphology evolution, of the catalyst during the accelerated degradation test were characterized by the Cu-stripping voltammetry and the TEM/SEM observations. From the various characterization results, it is revealed that both the high alloying degree and the pore confinement of PtRu nanoalloys play significant roles in suppressing the degradation processes, including Ru dissolution and particle agglomeration/migration. This report provides an opportunity for efficient design and fabrication of highly stable bimetallic or trimetallic electrocatalysts in a large variety of applications. PMID:25280180

  1. Ferroportin mediates the intestinal absorption of iron from a nanoparticulate ferritin core mimetic in mice

    PubMed Central

    Aslam, Mohamad F.; Frazer, David M.; Faria, Nuno; Bruggraber, Sylvaine F. A.; Wilkins, Sarah J.; Mirciov, Cornel; Powell, Jonathan J.; Anderson, Greg J.; Pereira, Dora I. A.

    2014-01-01

    The ferritin core is composed of fine nanoparticulate Fe3+ oxohydroxide, and we have developed a synthetic mimetic, nanoparticulate Fe3+ polyoxohydroxide (nanoFe3+). The aim of this study was to determine how dietary iron derived in this fashion is absorbed in the duodenum. Following a 4 wk run-in on an Fe-deficient diet, mice with intestinal-specific disruption of the Fpn-1 gene (Fpn-KO), or littermate wild-type (WT) controls, were supplemented with Fe2+ sulfate (FeSO4), nanoFe3+, or no added Fe for a further 4 wk. A control group was Fe sufficient throughout. Direct intestinal absorption of nanoFe3+ was investigated using isolated duodenal loops. Our data show that FeSO4 and nanoFe3+ are equally bioavailable in WT mice, and at wk 8 the mean ± sem hemoglobin increase was 18 ± 7 g/L in the FeSO4 group and 30 ± 5 g/L in the nanoFe3+ group. Oral iron failed to be utilized by Fpn-KO mice and was retained in enterocytes, irrespective of the iron source. In summary, although nanoFe3+ is taken up directly by the duodenum its homeostasis is under the normal regulatory control of dietary iron absorption, namely via ferroportin-dependent efflux from enterocytes, and thus offers potential as a novel oral iron supplement.—Aslam, M. F., Frazer, D. M., Faria, N., Bruggraber, S. F. A., Wilkins, S. J., Mirciov, C., Powell, J. J., Anderson, G. J., Pereira, D. I. A. Ferroportin mediates the intestinal absorption of iron from a nanoparticulate ferritin core mimetic in mice. PMID:24776745

  2. Rapid detection of cancer related DNA nanoparticulate biomarkers and nanoparticles in whole blood

    NASA Astrophysics Data System (ADS)

    Heller, Michael J.; Krishnan, Raj; Sonnenberg, Avery

    2010-08-01

    The ability to rapidly detect cell free circulating (cfc) DNA, cfc-RNA, exosomes and other nanoparticulate disease biomarkers as well as drug delivery nanoparticles directly in blood is a major challenge for nanomedicine. We now show that microarray and new high voltage dielectrophoretic (DEP) devices can be used to rapidly isolate and detect cfc-DNA nanoparticulates and nanoparticles directly from whole blood and other high conductance samples (plasma, serum, urine, etc.). At DEP frequencies of 5kHz-10kHz both fluorescent-stained high molecular weight (hmw) DNA, cfc-DNA and fluorescent nanoparticles separate from the blood and become highly concentrated at specific DEP highfield regions over the microelectrodes, while blood cells move to the DEP low field-regions. The blood cells can then be removed by a simple fluidic wash while the DNA and nanoparticles remain highly concentrated. The hmw-DNA could be detected at a level of <260ng/ml and the nanoparticles at <9.5 x 109 particles/ml, detection levels that are well within the range for viable clinical diagnostics and drug nanoparticle monitoring. Disease specific cfc-DNA materials could also be detected directly in blood from patients with Chronic Lymphocytic Leukemia (CLL) and confirmed by PCR genotyping analysis.

  3. Structure evolution of nanoparticulate Fe2O3.

    PubMed

    Erlebach, Andreas; Kurland, Heinz-Dieter; Grabow, Janet; Müller, Frank A; Sierka, Marek

    2015-02-21

    The atomic structure and properties of nanoparticulate Fe2O3 are characterized starting from its smallest Fe2O3 building unit through (Fe2O3)n clusters to nanometer-sized Fe2O3 particles. This is achieved by combining global structure optimizations at the density functional theory level, molecular dynamics simulations by employing tailored, ab initio parameterized interatomic potential functions and experiments. With the exception of nearly tetrahedral, adamantane-like (Fe2O3)2 small (Fe2O3)n clusters assume compact, virtually amorphous structures with little or no symmetry. For n = 2-5 (Fe2O3)n clusters consist mainly of two- and three-membered Fe-O rings. Starting from n = 5 they increasingly assume tetrahedral shape with the adamantane-like (Fe2O3)2 unit as the main building block. However, the small energy differences between different isomers of the same cluster-size make precise structural assignment for larger (Fe2O3)n clusters difficult. The tetrahedral morphology persists for Fe2O3 nanoparticles with up to 3 nm in diameter. Simulated crystallization of larger nanoparticles with diameters of about 5 nm demonstrates pronounced melting point depression and leads to formation of ?-Fe2O3 single crystals with hexagonal morphology. This finding is in excellent agreement with the results obtained for Fe2O3 nanopowders generated by laser vaporization and provides the first direct indication that ?-Fe2O3 may be thermodynamically the most stable phase in this size regime. PMID:25587689

  4. Effect of the Pt/Ru intermetallic boundary on the carbon monoxide electrooxidation: Excess electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Rau, María S.; Gennero de Chialvo, María R.; Chialvo, Abel C.

    2012-10-01

    The carbon monoxide oxidation reaction was studied on smooth Pt, Ru and Pt/Ru (Ru partially covered by Pt islands) rotating disc electrodes on acid solution saturated with CO gas (PCO = 1 atm) through steady state measurements. The current density vs. overpotential plot of the Pt/Ru electrode shows a profile qualitatively similar to the sum of both curves corresponding to pure Pt and Ru. On this basis, the excess electrocatalytic activity was defined as the difference between the current densities of the bimetallic electrode and those corresponding to the pure metals, which allowed evaluating the contribution of the intermetallic region to the reaction. It was verified that this property depends on overpotential, defining two ranges of positive excess values, 0.6 ? ?/V < 0.82 and 0.88 < ?/V ? 1.0, separated by the range 0.82 ? ?/V ? 0.88, where the contribution of the boundary region is negligible. A simple model was developed, which explains the experimental results on the basis of the spillover of the adsorbed reaction intermediates, while the reaction between adsorbed species on both sides of the intermetallic edge is not feasible.

  5. Synthesis of boron and nitrogen doped graphene supporting PtRu nanoparticles as catalysts for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Lu, Jiming; Zhou, Yingke; Tian, Xiaohui; Xu, Xiao; Zhu, Hongxi; Zhang, Shaowei; Yuan, Tao

    2014-10-01

    In this study, we demonstrate a single-step heat treatment approach to synthesize boron and nitrogen doped graphene supporting PtRu electrocatalysts for methanol electro-oxidation reaction. The reduction of graphene oxide, boron or nitrogen doping of graphene and loading of PtRu nanoparticles happened simultaneously during the reaction process. The morphologies and microstructures of the as-prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic methanol oxidation activity and durability of the obtained catalysts were evaluated by the cyclic voltammetry and chronoamperometric techniques. The results reveal that the boron and nitrogen doped graphene supporting PtRu electrocatalysts can be successfully prepared by the single step heat treatment technique, and the introduction of boron or nitrogen containing function groups into the reduced graphene sheets could modulate the particle size and dispersion of the supporting PtRu nanoparticles and improve the electrocatalytic performance of methanol oxidation reaction. The optimal annealing temperature is 800 °C, the preferable heat treatment time is 60 min for the nitrogen-doped catalysts and 90 min for the boron-doped catalysts, and the catalysts prepared under such conditions present superior catalytic activities for methanol oxidation than those prepared under other heat treatment conditions.

  6. Rapid synthesis of a PtRu nano-sponge with different surface compositions and performance evaluation for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Xiao, Meiling; Feng, Ligang; Zhu, Jianbing; Liu, Changpeng; Xing, Wei

    2015-05-01

    A rapid strategy to synthesize a highly active PtRu alloy nano-sponge catalyst system for methanol electro-oxidation is presented. The greatly increased Pt utilization, anti-CO poisoning ability and electronic effect resulting from the porous nano-sponge structure could account for the performance improvement.

  7. Correction: Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts

    NASA Astrophysics Data System (ADS)

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-05-01

    Correction for `Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts' by Binay Prasai et al., Nanoscale, 2015, 7, 8122-8134.

  8. Nanoparticulate magnetite thin films as electrode materials for the fabrication of electrochemical capacitors

    Microsoft Academic Search

    Suh Cem Pang; Wai Hwa Khoh; Suk Fun Chin

    2010-01-01

    Magnetite nanoparticles in stable colloidal suspension were prepared by the co-precipitation method. Nanoparticulate magnetite\\u000a thin films on supporting stainless steel plates were prepared by drop-coating followed by heat treatment under controlled\\u000a conditions. The effects of calcination temperature and atmosphere on the microstructure and electrochemical properties of\\u000a nanoparticulate magnetite thin films were investigated. Nanoparticulate magnetite thin films prepared under optimized conditions

  9. Soft landing of bare PtRu nanoparticles for electrochemical reduction of oxygen.

    PubMed

    Johnson, Grant E; Colby, Robert; Engelhard, Mark; Moon, Daewon; Laskin, Julia

    2015-08-01

    Magnetron sputtering of two independent Pt and Ru targets coupled with inert gas aggregation in a modified commercial source has been combined with soft landing of mass-selected ions to prepare bare 4.5 nm diameter PtRu nanoparticles on glassy carbon electrodes with controlled size and morphology for electrochemical reduction of oxygen in solution. Employing atomic force microscopy (AFM) it is shown that the nanoparticles bind randomly to the glassy carbon electrode at a relatively low coverage of 7 × 10(4) ions ?m(-2) and that their average height is centered at 4.5 nm. Scanning transmission electron microscopy images obtained in the high-angle annular dark field mode (HAADF-STEM) further confirm that the soft-landed PtRu nanoparticles are uniform in size. Wide-area scans of the electrodes using X-ray photoelectron spectroscopy (XPS) reveal the presence of both Pt and Ru in atomic concentrations of ?9% and ?33%, respectively. Deconvolution of the high energy resolution XPS spectra in the Pt 4f and Ru 3d regions indicates the presence of both oxidized Pt and Ru. The substantially higher loading of Ru compared to Pt and enrichment of Pt at the surface of the nanoparticles is confirmed by wide-area analysis of the electrodes using time-of-flight medium energy ion scattering (TOF-MEIS) employing both 80 keV He(+) and O(+) ions. The activity of electrodes containing 7 × 10(4) ions ?m(-2) of bare 4.5 nm PtRu nanoparticles toward the electrochemical reduction of oxygen was evaluated employing cyclic voltammetry (CV) in 0.1 M HClO4 and 0.5 M H2SO4 solutions. In both electrolytes a pronounced reduction peak was observed during O2 purging of the solution that was not evident during purging with Ar. Repeated electrochemical cycling of the electrodes revealed little evolution in the shape or position of the voltammograms indicating high stability of the nanoparticles supported on glassy carbon. The reproducibility of the nanoparticle synthesis and deposition was evaluated by employing the same experimental parameters to prepare nanoparticles on glassy carbon electrodes on three occasions separated by several days. Surfaces with almost identical electrochemical behavior were observed with CV, demonstrating the highly reproducible preparation of bare nanoparticles using physical synthesis in the gas-phase combined with soft landing of mass-selected ions. PMID:26148814

  10. Highly Conductive Nanoparticulate Films Achieved at Low Sintering Temperatures

    NASA Astrophysics Data System (ADS)

    Nahar, Manuj; Keto, John W.; Becker, Michael F.; Kovar, Desiderio

    2015-02-01

    Nanoparticulate Ag films have been produced by the laser ablation of microparticle aerosol (LAMA) deposition process. LAMA enables the production of thick, nanoparticulate films that are free of organics and offers the ability to control the degree of agglomeration and initial film density. The films were subsequently annealed at a range of temperatures from 100°C to 250°C to densify the films and increase conductivity. We show that, by reducing the degree of agglomeration in the films, sintering of LAMA-produced films occurs at low temperatures and results in near fully dense Ag films that exhibit an order of magnitude higher conductivity when compared to thick films produced by other techniques that are sintered at similar temperatures. Good agreement is observed between experiments and a sintering model that suggests that surface diffusion is dominant at temperatures below 150°C, and a combination of surface and grain boundary diffusion are responsible for sintering at slightly higher temperatures.

  11. Catalysts for direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Rice, C.; Ha, S.; Masel, R. I.; Wieckowski, A.

    Previous work has demonstrated that formic acid fuel cells show interesting properties for micro power generation. In this paper the effects of the anode catalyst composition on fuel cell performance is investigated. In particular, the performance of Pt, Pt/Pd and Pt/Ru catalysts for direct formic acid fuel cells is investigated and their effect on cell power density output at 30 °C are compared. It is found that the open cell potential varies significantly with the catalyst composition. The Pt/Pd catalyst shows an open cell potential of 0.91 V compared to 0.71 V with pure platinum and 0.59 V with Pt/Ru. The current at a cell potential of 0.5 V is 62 mA/cm 2 with Pt/Pd compared to 33 mA/cm 2 with pure platinum and 38 mA/cm 2 with Pt/Ru. Interestingly, the Pt/Ru catalyst gives the most power at low voltage 70 mW/cm 2 at 0.26 V, compared to 43 mW/cm 2 for pure platinum and 41 mW/cm 2 for Pt/Pd. All of the catalysts showed stable operation during several hour tests. Analysis of the data indicates that the addition of palladium enhances the rate of formic acid electrooxidation via a direct reaction mechanism, while ruthenium additions suppress the direct pathway and enhance electrooxidation via a reactive CO intermediate.

  12. Mechanisms of Tumor Vascular Priming by a Nanoparticulate Doxorubicin Formulation

    PubMed Central

    Chaudhuri, Tista Roy; Arnold, Robert D.; Yang, Jun; Turowski, Steven G.; Qu, Yang; Spernyak, Joseph A.; Mazurchuk, Richard; Mager, Donald E.

    2013-01-01

    Purpose Tumor vascular normalization by antiangiogenic agents may increase tumor perfusion but reestablish vascular barrier properties in CNS tumors. Vascular priming via nanoparticulate carriers represents a mechanistically distinct alternative. This study investigated mechanisms by which sterically-stabilized liposomal doxorubicin (SSL-DXR) modulates tumor vascular properties. Methods Functional vascular responses to SSL-DXR were investigated in orthotopic rat brain tumors using deposition of fluorescent permeability probes and dynamic contrast-enhanced magnetic resonance imaging. Microvessel density and tumor burden were quantified by immunohistochemistry (CD-31) and quantitative RT-PCR (VE-cadherin). Results Administration of SSL-DXR (5.7 mg/kg iv) initially (3–4 days post-treatment) decreased tumor vascular permeability, ktrans (vascular exchange constant), vascular endothelial cell content, microvessel density, and deposition of nanoparticulates. Tumor vasculature became less chaotic. Permeability and perfusion returned to control values 6–7 days post-treatment, but intratumor SSL-DXR depot continued to effect tumor vascular endothelial compartment 7–10 days post-treatment, mediating enhanced permeability. Conclusions SSL-DXR ultimately increased tumor vascular permeability, but initially normalized tumor vasculature and decreased tumor perfusion, permeability, and nanoparticulate deposition. These temporal changes in vascular integrity resulting from a single SSL-DXR dose have important implications for the design of combination therapies incorporating nanoparticle-based agents for tumor vascular priming. PMID:22798260

  13. Carbon support effects on bimetallic Pt-Ru nanoparticles formed from molecular precursors

    SciTech Connect

    Hills, C.W.; Nashner, M.S.; Frenkel, A.I.; Shapley, J.R.; Nuzzo, R.G. [Univ. of Illinois, Urbana, IL (United States)] [Univ. of Illinois, Urbana, IL (United States)

    1999-02-02

    The authors describe the preparation, structural characterization, and support interactions experienced by two different compositions of Pt-Ru nanoparticles supported on several carbons (carbon black, fullerene soot, and desulfurized carbon black). The bimetallic nanoparticles, obtained by reduction of the neutral molecular precursors PtRu{sub 5}C(CO){sub 16} and Pt{sub 2}Ru{sub 4}(CO){sub 18} (the latter of which lacks a central stabilizing carbide core) at elevated temperatures in a hydrogen atmosphere, show a structural homology, exhibiting exceptionally narrow size and compositional distributions. A detailed structural picture of the nanoparticles has been deduced on the basis of in-situ extended X-ray absorption fine structure (EXAFS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray analysis (EDX), and X-ray absorption near edge structures (XANES). These techniques reveal that the bimetallic nanoparticles have Pt/Ru compositions of 1:5 and 2:4, respectively, and average diameters lying between 1.0 and 1.5 nm. The local metal coordination environments reveal a nonstatistical distribution of the two metals in the nanoparticles. Specifically, Pt shows a marked preference for segregation to the particle surfaces under an H{sub 2} atmosphere. The data also reveal a difference in the structural environment of the nanoparticles when formed on the fullerene soot support. Interactions between Ru and low-Z atoms are revealed through XANES, which, taken collectively with the other data presented, leads the authors to propose a possible Ru-C compound formation on this latter support phase.

  14. Structural and Architectural Evaluation of Bimetallic Nanoparticles: A Case Study of Pt?Ru Core?Shell and Alloy Nanoparticles

    Microsoft Academic Search

    Selim Alayoglu; Peter Zavalij; Bryan Eichhorn; Qi Wang; Anatoly I. Frenkel; Peter Chupas

    2009-01-01

    A comprehensive structural\\/architectural evaluation of the PtRu (1:1) alloy and Ru at Pt core-shell nanoparticles (NPs) provides spatially resolved structural information on sub-5 nm NPs. A combination of extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), pair distribution function (PDF) analyses, Debye function simulations of X-ray diffraction (XRD), and field emission transmission electron microscopy\\/energy dispersive spectroscopy

  15. Ultrasonically treated multi-walled carbon nanotubes (MWCNTs) as PtRu catalyst supports for methanol electrooxidation

    Microsoft Academic Search

    Chunwei Yang; Xinguo Hu; Dianlong Wang; Changsong Dai; Liang Zhang; Haibo Jin; Simeon Agathopoulos

    2006-01-01

    In the quest of fabricating supported catalysts, experimental results of transmission electron microscopy, Raman and infrared spectroscopy indicate that ultrasonic treatment effectively functionalizes multi-walled carbon nanotubes (MWCNTs), endowing them with groups that can act as nucleation sites which can favor well-dispersed depositions of PtRu clusters on their surface. Ultrasonic treatment seems to be superior than functionalization via regular refluxing. This

  16. Dispersion of nanoparticulate suspensions using self-assembled surfactant aggregates

    NASA Astrophysics Data System (ADS)

    Singh, Pankaj Kumar

    The dispersion of particles is critical for several industrial applications such as paints, inks, coatings, and cosmetics. Several emerging applications such as abrasives for precision polishing, and drug delivery systems are increasingly relying on nanoparticulates to achieve the desired performance. In the case of nanoparticles, the dispersion becomes more challenging because of the lack of fundamental understanding of dispersant adsorption and interparticle force prediction. Additionally, many of these processes use severe processing environments such as high normal forces (>100 mN/m), high shear forces (>10,000 s -1), and high ionic strengths (>0.1 M). Under such processing conditions, traditionally used dispersants based on electrostatics, and steric force repulsion mechanism may not be adequate. Hence, the development of optimally performing dispersants requires a fundamental understanding of the dispersion mechanism at the atomic/molecular scale. This study explores the use of self-assembled surfactant aggregates at the solid-liquid interface for dispersing nanoparticles in severe processing environments. Surfactant molecules can provide a feasible alternative to polymeric or inorganic dispersants for stabilizing ultrafine particles. The barrier to aggregation in the presence of surfactant molecules was measured using atomic force microscopy. The barrier heights correlated to suspension stability. To understand the mechanism for nanoparticulate suspension stability in the presence of surfactant films, the interface was characterized using zeta potential, contact angle, adsorption, and FT-IR (adsorbed surfactant film structure measurements). The effect of solution conditions such as pH and ionic strength on the suspension stability, and the self-assembled surfactant films was also investigated. It was determined that a transition from a random to an ordered orientation of the surfactant molecules at the interface was responsible for stability of nanoparticulates. Additionally, the role of the surface in surfactant self-assembly was investigated. Mechanical and thermodynamic properties of the self-assembled layer at the solid-liquid interface were calculated based on experimental results, and compared to the corresponding properties in the bulk solution.

  17. A review of research on nanoparticulate flow undergoing coagulation

    NASA Astrophysics Data System (ADS)

    Lin, Jianzhong; Huo, Linlin

    2015-05-01

    Nanoparticulate flows occur in a wide range of natural phenomena and engineering applications and, hence, have attracted much attention. The purpose of the present paper is to provide a review of the research conducted over the last decade. The research covered relates to the Brownian coagulation of monodisperse and polydisperse particles, the Taylor-series expansion method of moment, and nanoparticle distributions due to coagulation in pipe and channel flow, jet flow, and the mixing layer and in the process of flame synthesis and deposition.

  18. The Mechanism of Direct Formic Acid Fuel Cell Using Pd, Pt and Pt-Ru

    Microsoft Academic Search

    Nobuyuki Kamiya; Yan Liu; Shigenori Mitsushima; Ken-Ichiro Ota; Yasuyuki Tsutsumi; Naoya Ogawa; Norihiro Kon; Mika Eguchi

    2008-01-01

    The electro-oxidation of formic acid, 2-propanol and methanol on Pd black, Pd\\/C, Pt-Ru\\/C and Pt\\/C has been investigated to clear the reaction mechanism. It was suggested that the formic acid is dehydrogenated on Pd surface and the hydrogen is occluded in the Pd lattice. Thus obtained hydrogen acts like pure hydrogen supplied from the outside and the cell performance of

  19. CO electrooxidation study on Pt and Pt-Ru in H3PO4 using MEA with PBI-H3PO4 membrane

    NASA Astrophysics Data System (ADS)

    Modestov, A. D.; Tarasevich, M. R.; Leykin, A. Y.

    2011-03-01

    CO electrooxidation on Pt and Pt-Ru in H3PO4 was studied in the temperature range 120-180 °C using CO-N2-H2O gas mixtures of controlled composition. On Pt and Pt-Ru the voltammetry curves exhibited Tafel behavior in a wide potential range with a slope of 80-100 mV per decade. Replacement of Pt with Pt-Ru on the anode resulted mainly in a shift of CO electrooxidation voltammetry curves by approx. -0.3 V. Reaction order in respect to water vapor pressure was found close to unity with both electrocatalysts. Reaction order in respect to CO partial pressure was found negative, close to zero. Values of apparent activation energy of CO electrooxidation on these electrocatalysts were nearly equal, Ea app = 110 ± 15 kJ mol-1. The results were interpreted within the framework of Langmuir-Hinshelwood mechanism. An equation, which describes the observed features of CO electrooxidation on Pt and Pt-Ru, was suggested. Comparing results of the present study with results of earlier studies of CO tolerance of Pt and Pt-Ru electrocatalysts, it was concluded that CO electrooxidation can hardly play a significant role in CO tolerance of PEM FC with PBI-PA membranes.

  20. Improved reaction kinetics and selectivity by the TiO2-embedded carbon nanofiber support for electro-oxidation of ethanol on PtRu nanoparticles

    NASA Astrophysics Data System (ADS)

    Nakagawa, Nobuyoshi; Ito, Yudai; Tsujiguchi, Takuya; Ishitobi, Hirokazu

    2014-02-01

    The electro-oxidation of ethanol by the catalyst of PtRu nanoparticles supported on a TiO2-embedded carbon nanofiber (PtRu/TECNF), which has recently been proposed by the authors as a highly active catalyst for methanol oxidation, is investigated by cyclic voltammetry using a glassy carbon electrode and by operating a direct ethanol fuel cell (DEFC) with the catalyst. The mass activity obtained from the cyclic voltammogram for the ethanol oxidation is compared to that for the methanol oxidation reported in our recent paper. The mass activity for the ethanol oxidation is comparable or slightly higher than that for the methanol oxidation, and the relationship between the TECNF composition, i.e., the Ti/C mass ratio, and the activity are also similar to that for the methanol oxidation. A DEFC fabricated with the PtRu/TECNF shows a higher power output compared to that with the commercial PtRu/C catalyst. An analysis of the reaction products by a simple two-step reaction model reveals that the PtRu/TECNF increases the rate constant for the reaction steps from ethanol to acetaldehyde and subsequently to CO2, but decreases that from acetaldehyde to acetic acid. This means that the PtRu/TECNF improves not only the kinetics, but also the selectivity to acetaldehyde.

  1. Concepts and practices used to develop functional PLGA-based nanoparticulate systems

    PubMed Central

    Sah, Hongkee; Thoma, Laura A; Desu, Hari R; Sah, Edel; Wood, George C

    2013-01-01

    The functionality of bare polylactide-co-glycolide (PLGA) nanoparticles is limited to drug depot or drug solubilization in their hard cores. They have inherent weaknesses as a drug-delivery system. For instance, when administered intravenously, the nanoparticles undergo rapid clearance from systemic circulation before reaching the site of action. Furthermore, plain PLGA nanoparticles cannot distinguish between different cell types. Recent research shows that surface functionalization of nanoparticles and development of new nanoparticulate dosage forms help overcome these delivery challenges and improve in vivo performance. Immense research efforts have propelled the development of diverse functional PLGA-based nanoparticulate delivery systems. Representative examples include PEGylated micelles/nanoparticles (PEG, polyethylene glycol), polyplexes, polymersomes, core-shell–type lipid-PLGA hybrids, cell-PLGA hybrids, receptor-specific ligand-PLGA conjugates, and theranostics. Each PLGA-based nanoparticulate dosage form has specific features that distinguish it from other nanoparticulate systems. This review focuses on fundamental concepts and practices that are used in the development of various functional nanoparticulate dosage forms. We describe how the attributes of these functional nanoparticulate forms might contribute to achievement of desired therapeutic effects that are not attainable using conventional therapies. Functional PLGA-based nanoparticulate systems are expected to deliver chemotherapeutic, diagnostic, and imaging agents in a highly selective and effective manner. PMID:23459088

  2. Concepts and practices used to develop functional PLGA-based nanoparticulate systems.

    PubMed

    Sah, Hongkee; Thoma, Laura A; Desu, Hari R; Sah, Edel; Wood, George C

    2013-01-01

    The functionality of bare polylactide-co-glycolide (PLGA) nanoparticles is limited to drug depot or drug solubilization in their hard cores. They have inherent weaknesses as a drug-delivery system. For instance, when administered intravenously, the nanoparticles undergo rapid clearance from systemic circulation before reaching the site of action. Furthermore, plain PLGA nanoparticles cannot distinguish between different cell types. Recent research shows that surface functionalization of nanoparticles and development of new nanoparticulate dosage forms help overcome these delivery challenges and improve in vivo performance. Immense research efforts have propelled the development of diverse functional PLGA-based nanoparticulate delivery systems. Representative examples include PEGylated micelles/nanoparticles (PEG, polyethylene glycol), polyplexes, polymersomes, core-shell-type lipid-PLGA hybrids, cell-PLGA hybrids, receptor-specific ligand-PLGA conjugates, and theranostics. Each PLGA-based nanoparticulate dosage form has specific features that distinguish it from other nanoparticulate systems. This review focuses on fundamental concepts and practices that are used in the development of various functional nanoparticulate dosage forms. We describe how the attributes of these functional nanoparticulate forms might contribute to achievement of desired therapeutic effects that are not attainable using conventional therapies. Functional PLGA-based nanoparticulate systems are expected to deliver chemotherapeutic, diagnostic, and imaging agents in a highly selective and effective manner. PMID:23459088

  3. A study of formaldehyde formation during methanol oxidation over PtRu bulk alloys and nanometer scale catalyst

    Microsoft Academic Search

    Mohsina Islam; Rukma Basnayake; Carol Korzeniewski

    2007-01-01

    The oxidation of 1.0M CH3OH in 0.1M H2SO4 was carried out over PtRu bulk alloy and nanometer scale catalyst materials. The H2CO produced as a stable by-product during brief (180s) electrolysis periods was determined quantitatively for potentials (measured vs a reversible hydrogen electrode reference) in the range of 0.5–0.8V. Electrolysis was performed in a cell that accommodated a small (?50?L)

  4. Pharmaceutical Properties of Nanoparticulate Formulation Composed of TPGS and PLGA for Controlled Delivery of Anticancer Drug

    E-print Network

    Mu, L.

    A suitable management of the pharmaceutical property is needed and helpful to design a desired nanoparticulate delivery system, which includes the carrier nature, particle size and size distribution, morphology, surfactant ...

  5. SIMULATION NUMRIQUE DE LA CONDENSATION/VAPORATION ET DE LA COAGULATION DES NANOPARTICULES.

    E-print Network

    Paris-Sud XI, Université de

    SIMULATION NUMÉRIQUE DE LA CONDENSATION/ÉVAPORATION ET DE LA COAGULATION DES NANOPARTICULES. M simulation of condensational growth, evaporation and coagulation of nanoparticles. ABSTRACT Aware. This first study addresses condensational growth, evaporation and coagulation. The model is to be integrated

  6. A TEM analysis of nanoparticulates in a Polar ice core

    SciTech Connect

    Esquivel, E.V.; Murr, L.E

    2004-03-15

    This paper explores the prospect for analyzing nanoparticulates in age-dated ice cores representing times in antiquity to establish a historical reference for atmospheric particulate regimes. Analytical transmission electron microscope (TEM) techniques were utilized to observe representative ice-melt water drops dried down on carbon/formvar or similar coated grids. A 10,000-year-old Greenland ice core was melted, and representative water drops were transferred to coated grids in a clean room environment. Essentially, all particulates observed were aggregates and either crystalline or complex mixtures of nanocrystals. Especially notable was the observation of carbon nanotubes and related fullerene-like nanocrystal forms. These observations are similar with some aspects of contemporary airborne particulates including carbon nanotubes and complex nanocrystal aggregates.

  7. Multifunctional, stimuli-sensitive nanoparticulate systems for drug delivery

    PubMed Central

    Torchilin, Vladimir P.

    2015-01-01

    The use of nanoparticulate pharmaceutical drug delivery systems (NDDSs) to enhance the in vivo effectiveness of drugs is now well established. The development of multifunctional and stimulus-sensitive NDDSs is an active area of current research. Such NDDSs can have long circulation times, target the site of the disease and enhance the intracellular delivery of a drug. This type of NDDS can also respond to local stimuli that are characteristic of the pathological site by, for example, releasing an entrapped drug or shedding a protective coating, thus facilitating the interaction between drug-loaded nanocarriers and target cells or tissues. In addition, imaging contrast moieties can be attached to these carriers to track their real-time biodistribution and accumulation in target cells or tissues. Here, I highlight recent developments with multifunctional and stimuli-sensitive NDDSs and their therapeutic potential for diseases including cancer, cardiovascular diseases and infectious diseases. PMID:25287120

  8. Correction: Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts.

    PubMed

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-06-14

    Correction for 'Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts' by Binay Prasai et al., Nanoscale, 2015, 7, 8122-8134. PMID:25982103

  9. Nanoparticules d'or: De l'imagerie par resonance magnetique a la radiosensibilisation

    NASA Astrophysics Data System (ADS)

    Hebert, Etienne M.

    Cette thèse approfondit l'étude de nanoparticules d'or de 5 nm de diamètre recouvertes de diamideéthanethioldiethylènetriaminepentacétate de gadolinium (DTDTPA:Gd), un agent de contraste pour l'imagerie par résonance magnétique (IRM). En guise de ciblage passif, la taille des nanoparticules a été contrôlée afin d'utiliser le réseau de néovaisseaux poreux et perméable des tumeurs. De plus les tumeurs ont un drainage lymphatique déficient qui permet aux nanoparticules de demeurer plus longtemps dans le milieu interstitiel de la tumeur. Les expériences ont été effectuées sur des souris Balb/c femelles portant des tumeurs MC7-L1. La concentration de nanoparticules a pu être mesurée à l'IRM in vivo. La concentration maximale se retrouvait à la fin de l'infusion de 10 min. La concentration s'élevait à 0.3 mM dans la tumeur et de 0.12 mM dans le muscle environnant. Les nanoparticules étaient éliminées avec une demi-vie de 22 min pour les tumeurs et de 20 min pour le muscle environnant. Les nanoparticules ont été fonctionnalisées avec le peptide Tat afin de leur conférer des propriétés de ciblage actif La rétention de ces nanoparticules a ainsi été augmentée de 1600 %, passant d'une demi-vie d'élimination de 22 min à 350 min. La survie des souris a été mesurée à l'aide de courbes Kaplan-Meier et d'un modèle mathématique évalue l'efficacité de traitements. Le modèle nous permet, à l'aide de la vitesse de croissance des tumeurs et de l'efficacité des traitements, de calculer la courbe de survie des spécimens. Un effet antagoniste a été observé au lieu de l'effet synergétique attendu entre une infusion de Au@DTDTPA:Gd et l'irradiation aux rayons X. L'absence d'effet synergétique a été attribuée à l'épaisseur du recouvrement de DTDTPA:Gd qui fait écran aux électrons produits par l'or. De plus, le moyen d'ancrage du recouvrement utilise des thiols qui peuvent s'avérer être des capteurs de radicaux. De plus, contrairement a ce qui était escompté, un effet chimiothérapeutique de ces nanoparticules a été observé in vitro et in vivo. Par contre, le mécanisme précis de cet effet est encore à être expliquer, mais on sait déjà que les nanoparticules d'or affectent les fonctions des macrophages ainsi que l'angiogenèse. MOTS-CLÉS : Radiosensibilisateur, Nanoparticules d'or, Agent de contraste pour l'IRM, Électrons de basses énergies, Kaplan-Meier, Effet chimiothérapeutique.

  10. Dynamics of discontinuous coating and drying of nanoparticulate films.

    SciTech Connect

    Schunk, Peter Randall; Dunphy, Darren Robert (University of New Mexico, Albuquerque, NM); Brinker, C. Jeffrey; Tjiptowidjojo, Kristianto (University of New Mexico, Albuquerque, NM)

    2010-09-01

    Heightened interest in micro-scale and nano-scale patterning by imprinting, embossing, and nano-particulate suspension coating stems from a recent surge in development of higher-throughput manufacturing methods for integrated devices. Energy-applications addressing alternative, renewable energy sources offer many examples of the need for improved manufacturing technology for micro and nano-structured films. In this presentation we address one approach to micro- and nano-pattering coating using film deposition and differential wetting of nanoparticles suspensions. Rather than print nanoparticle or colloidal inks in discontinuous patches, which typically employs ink jet printing technology, patterns can be formed with controlled dewetting of a continuously coated film. Here we report the dynamics of a volatile organic solvent laden with nanoparticles dispensed on the surfaces of water droplets, whose contact angles (surface energy) and perimeters are defined by lithographic patterning of initially (super)hydrophobic surfaces.. The lubrication flow equation together with averaged particle transport equation are employed to predict the film thickness and particle average concentration profiles during subsequent drying of the organic and water solvents. The predictions are validated by contact angle measurements, in situ grazing incidence small angle x-ray scattering experiments, and TEM images of the final nanoparticle assemblies.

  11. Microstructures and Nanostructures for Environmental Carbon Nanotubes and Nanoparticulate Soots

    PubMed Central

    Murr, L. E.

    2008-01-01

    This paper examines the microstructures and nanostructures for natural (mined) chrysotile asbestos nanotubes (Mg3 Si2O5 (OH)4) in comparison with commercial multiwall carbon nanotubes (MWCNTs), utilizing scanning and transmission electron microscopy (SEM and TEM). Black carbon (BC) and a variety of specific soot particulate (aggregate) microstructures and nanostructures are also examined comparatively by SEM and TEM. A range of MWCNTs collected in the environment (both indoor and outdoor) are also examined and shown to be similar to some commercial MWCNTs but to exhibit a diversity of microstructures and nanostructures, including aggregation with other multiconcentric fullerenic nanoparticles. MWCNTs formed in the environment nucleate from special hemispherical graphene “caps” and there is evidence for preferential or energetically favorable chiralities, tube growth, and closing. The multiconcentric graphene tubes (?5 to 50 nm diameter) differentiate themselves from multiconcentric fullerenic nanoparticles and especially turbostratic BC and carbonaceous soot nanospherules (?8 to 80 nm diameter) because the latter are composed of curved graphene fragments intermixed or intercalated with polycyclic aromatic hydrocarbon (PAH) isomers of varying molecular weights and mass concentrations; depending upon combustion conditions and sources. The functionalizing of these nanostructures and photoxidation and related photothermal phenomena, as these may influence the cytotoxicities of these nanoparticulate aggregates, will also be discussed in the context of nanostructures and nanostructure phenomena, and implications for respiratory health. PMID:19151426

  12. CROISSANCE DE NANOPARTICULES D'ARGENT PAR INSOLATION LASER ULTRAVIOLETTE CONTINUE DANS DES VERRES SODA-LIME

    E-print Network

    Paris-Sud XI, Université de

    CROISSANCE DE NANOPARTICULES D'ARGENT PAR INSOLATION LASER ULTRAVIOLETTE CONTINUE DANS DES VERRES concentration dans des verres soda-lime par insolation laser continue à 244 nm. L'originalité de cette-CLEFS : nanoparticules ; argent ; verres soda-lime ; coalescence. 1. INTRODUCTION La croissance de NP d'argent peut être

  13. A review of the formation and classification of amphiphilic block copolymer nanoparticulate structures: micelles, nanospheres, nanocapsules and polymersomes

    Microsoft Academic Search

    Kevin Letchford; Helen Burt

    2007-01-01

    Amphiphilic block copolymers are able to form a range of different nanoparticulate structures. These include micelles, nanospheres, nanocapsules, and polymersomes. This review attempts to clarify some of the terminology used in the literature by providing an overview of the major features of each type of nanoparticle and the factors that influence the formation of particular nanoparticulate formulations.

  14. Methanol electrooxidation at mesoporous Pt and Pt-Ru electrodes: A comparative study with carbon supported materials

    NASA Astrophysics Data System (ADS)

    García, Gonzalo; Florez-Montaño, Jonathan; Hernandez-Creus, Alberto; Pastor, Elena; Planes, Gabriel A.

    2011-03-01

    The electrochemical behaviour of fuel cell catalysts (mesoporous Pt (MPPt), MPPtRu, MPPt modified by adsorbed Ru (MPPt/Ru) and carbon supported PtRu alloy) was studied using the thin layer flow cell differential electrochemical mass spectrometry (TLFC-DEMS) technique. The catalysts present high catalytic activity towards the methanol oxidation reaction (MOR), being the PtRu/C electrode the least active for MOR, while MPPt/Ru presents higher current densities for this reaction than MPPtRu. The results suggest that the diffusion properties obtained in the porous structure of the MP electrodes and the surface atomic arrangement in the electrode are the main reasons for the higher catalytic activity achieved. Finally, TLFC-DEMS was proved to be a powerful technique which evaluates and correlates the CO2 efficiency with the catalytic activity and the porous structure of the catalysts.

  15. Chemical components, pharmacological properties, and nanoparticulate delivery systems of Brucea javanica

    PubMed Central

    Chen, Meiwan; Chen, Ruie; Wang, Shengpeng; Tan, Wen; Hu, Yangyang; Peng, Xinsheng; Wang, Yitao

    2013-01-01

    Brucea javanica has demonstrated a variety of antitumoral, antimalarial, and anti- inflammatory properties. As a Chinese herbal medicine, Brucea javanica is mainly used in the treatment of lung and gastrointestinal cancers. Pharmacological research has identified the main antitumor components are tetracyclic triterpene quassinoids. However, most of these active components have poor water solubility and low bioavailability, which greatly limit their clinical application. Nanoparticulate delivery systems are urgently needed to improve the bioavailability of Brucea javanica. This paper mainly focuses on the chemical components in Brucea javanica and its pharmacological properties and nanoparticulate formulations, in an attempt to encourage further research on its active components and nanoparticulate drug delivery systems to expand its clinical applications. It is expected to improve the level of pharmaceutical research and provide a strong scientific foundation for further study on the medicinal properties of this plant. PMID:23319860

  16. Cellular partitioning of nanoparticulate versus dissolved metals in marine phytoplankton.

    PubMed

    Bielmyer-Fraser, Gretchen K; Jarvis, Tayler A; Lenihan, Hunter S; Miller, Robert J

    2014-11-18

    Discharges of metal oxide nanoparticles into aquatic environments are increasing with their use in society, thereby increasing exposure risk for aquatic organisms. Separating the impacts of nanoparticle from dissolved metal pollution is critical for assessing the environmental risks of the rapidly growing nanomaterial industry, especially in terms of ecosystem effects. Metal oxides negatively affect several species of marine phytoplankton, which are responsible for most marine primary production. Whether such toxicity is generally due to nanoparticles or exposure to dissolved metals liberated from particles is uncertain. The type and severity of toxicity depends in part on whether phytoplankton cells take up and accumulate primarily nanoparticles or dissolved metal ions. We compared the responses of the marine diatom, Thalassiosira weissflogii, exposed to ZnO, AgO, and CuO nanoparticles with the responses of T. weissflogii cells exposed to the dissolved metals ZnCl2, AgNO3, and CuCl2 for 7 d. Cellular metal accumulation, metal distribution, and algal population growth were measured to elucidate differences in exposure to the different forms of metal. Concentration-dependent metal accumulation and reduced population growth were observed in T. weissflogii exposed to nanometal oxides, as well as dissolved metals. Significant effects on population growth were observed at the lowest concentrations tested for all metals, with similar toxicity for both dissolved and nanoparticulate metals. Cellular metal distribution, however, markedly differed between T. weissflogii exposed to nanometal oxides versus those exposed to dissolved metals. Metal concentrations were highest in the algal cell wall when cells were exposed to metal oxide nanoparticles, whereas algae exposed to dissolved metals had higher proportions of metal in the organelle and endoplasmic reticulum fractions. These results have implications for marine plankton communities as well as higher trophic levels, since metal may be transferred from phytoplankton through food webs vis à vis grazing by zooplankton or other pathways. PMID:25337629

  17. On the differences in the reaction mechanism for CO and CO/H{sub 2} electrooxidation on PtRu and PtSn alloy electrodes

    SciTech Connect

    Gasteiger, H.A. [Univ. Ulm (Germany). Abteilung Oberflaechenchemie und Katalyse; Markovic, N.M.; Ross, P.N. Jr. [Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Electrooxidation kinetics of mixtures of carbon monoxide and hydrogen were studied on well-characterized surfaces of Pt and alloys of PtRu and PtSn in 0.5 M H{sub 2}SO{sub 4} at room temperature and 60 C. The alloy electrode surfaces were prepared in UHV by sputter/anneal cycles and their surface compositions were determined via low energy ion scattering. Subsequently, the electrodes were transferred contamination-free from UHV into a rotating disk electrode (RDE) configuration in a conventional electrochemical cell and their activity was measured both by CO stripping voltammetry and under the continuous flow of CO and CO/H{sub 2} gas mixtures in RDE-experiments. The overpotential for the continuous oxidation of pure CO on PtSn electrodes with a Sn surface composition of x{sub Sn,s} {approximately} 0.2 is significantly smaller than on PtRu alloys (x{sub Ru,s} {approximately} 0.5) and on pure Pt. The reaction order with respect to solution phase CO is negative on PtRu alloys due to the competition between OH{sub ads} nucleation and CO adsorption on Ru surface atoms. Owing to the lack of CO adsorption on OH{sub ads}-providing Sn surface atoms, the reaction order with respect to CO is positive on PtSn electrodes. Therefore, the activity enhancement of PtSn electrodes versus PtRu and Pt electrodes is most pronounced in pure CO and decreases with the CO concentration in CO/N{sub 2} and CO/H{sub 2} mixtures.

  18. Nanoparticulate delivery of agents for induced elastogenesis in three-dimensional collagenous matrices.

    PubMed

    Venkataraman, Lavanya; Sivaraman, Balakrishnan; Vaidya, Pratik; Ramamurthi, Anand

    2014-04-16

    The degradation of elastic matrix in the infrarenal aortic wall is a critical parameter underlying the formation and progression of abdominal aortic aneurysms. It is mediated by the chronic overexpression of matrix metalloprotease (MMP)-2 and MMP-9, leading to a progressive loss of elasticity and weakening of the aortic wall. Delivery of therapeutic agents to inhibit MMPs, while concurrently coaxing cell-based regenerative repair of the elastic matrix represents a potential strategy for slowing or arresting abdominal aortic aneurysm growth. Previous studies have demonstrated elastogenic induction of healthy and aneurysmal aortic smooth muscle cells and inhibition of MMPs, following exogenous delivery of elastogenic factors such as transforming growth factor (TGF)-?1, as well as MMP-inhibitors such as doxycycline (DOX) in two-dimensional culture. Based on these findings, and others that demonstrated elastogenic benefits of nanoparticulate delivery of these agents in two-dimensional culture, poly(lactide-co-glycolide) nanoparticles were developed for localized, controlled and sustained delivery of DOX and TGF-?1 to human aortic smooth muscle cells within a three-dimensional gels of type I collagen, which closely simulate the arterial tissue microenvironment. DOX and TGF-?1 released from these nanoparticles influenced elastogenic outcomes positively within the collagen constructs over 21 days of culture, which were comparable to that induced by exogenous supplementation of DOX and TGF-?1 within the culture medium. However, this was accomplished at doses ~20-fold lower than the exogenous dosages of the agents, illustrating that their localized, controlled and sustained delivery from nanoparticles embedded within a three-dimensional scaffold is an efficient strategy for directed elastogenesis. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24737693

  19. Electrochromism of nanoparticulate-doped metal oxides: optical and material properties

    Microsoft Academic Search

    J. P Coleman; J. J Freeman; P Madhukar; J. H Wagenknecht

    1999-01-01

    Nanoparticulate antimony-doped tin oxide (ATO) has been used as the electrochromic material for the production of printed, interdigitated electrochromic displays. We report here some results on elemental and ionic modifications to the ATO in an attempt to improve electrochromic switching. We have also briefly studied the effects of antimony and tin distribution in the mixed oxide by a sequential preparation

  20. X-ray phase computed tomography for nanoparticulated imaging probes and therapeutics: preliminary feasibility study

    NASA Astrophysics Data System (ADS)

    Tang, Xiangyang; Yang, Yi; Tang, Shaojie

    2011-03-01

    With the scientific progress in cancer biology, pharmacology and biomedical engineering, the nano-biotechnology based imaging probes and therapeutical agents (namely probes/agents) - a form of theranostics - are among the strategic solutions bearing the hope for the cure of cancer. The key feature distinguishing the nanoparticulated probes/agents from their conventional counterparts is their targeting capability. A large surface-to-volume ratio in nanoparticulated probes/agents enables the accommodation of multiple targeting, imaging and therapeutic components to cope with the intra- and inter-tumor heterogeneity. Most nanoparticulated probes/agents are synthesized with low atomic number materials and thus their x-ray attenuation are very similar to biological tissues. However, their microscopic structures are very different, which may result in significant differences in their refractive properties. Recently, the investigation in the x-ray grating-based differential phase contrast (DPC) CT has demonstrated its advantages in differentiating low-atomic materials over the conventional attenuation-based CT. We believe that a synergy of x-ray grating-based DPC CT and nanoparticulated imaging probes and therapeutic agents may play a significant role in extensive preclinical and clinical applications, or even become a modality for molecular imaging. Hence, we propose to image the refractive property of nanoparticulated imaging probes and therapeutical agents using x-ray grating-based DPC CT. In this work, we conduct a preliminary feasibility study with a focus to characterize the contrast-to-noise ratio (CNR) and contrast-detail behavior of the x-ray grating-based DPC CT. The obtained data may be instructive to the architecture design and performance optimization of the x-ray grating-based DPC CT for imaging biomarker-targeted imaging probes and therapeutic agents, and even informative to the translation of preclinical research in theranostics into clinical applications.

  1. Particle-Level Modeling of the Charge-Discharge Behavior of Nanoparticulate Phase-Separating Li-Ion Battery Electrodes

    E-print Network

    Orvananos, Bernardo

    In nanoparticulate phase-separating electrodes, phase separation inside the particles can be hindered during their charge/discharge cycles even when a thermodynamic driving force for phase separation exists. In such cases, ...

  2. Breakdown and Combustion of JP-10 Fuel Catalyzed by Nanoparticulate CeO2 and Fe2O3

    E-print Network

    Anderson, Scott L.

    Breakdown and Combustion of JP-10 Fuel Catalyzed by Nanoparticulate CeO2 and Fe2O3 Brian Van of nanoparticulate CeO2 and Fe2O3, was studied in a small alumina flow-tube reactor on time scales around 1 ms pyrolyzes at temperatures above 900 K to a variety of hydrocarbon products. In the absence of O2, both CeO2

  3. Analytical Electron Microscopy for Characterization of Fluid or Semi-Solid Multiphase Systems Containing Nanoparticulate Material

    PubMed Central

    Klang, Victoria; Valenta, Claudia; Matsko, Nadejda B.

    2013-01-01

    The analysis of nanomaterials in pharmaceutical or cosmetic preparations is an important aspect both in formulation development and quality control of marketed products. Despite the increased popularity of nanoparticulate compounds especially in dermal preparations such as emulsions, methods and protocols of analysis for the characterization of such systems are scarce. This work combines an original sample preparation procedure along with different methods of analytical electron microscopy for the comprehensive analysis of fluid or semi-solid dermal preparations containing nanoparticulate material. Energy-filtered transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy and high resolution imaging were performed on model emulsions and a marketed product to reveal different structural aspects of both the emulsion bulk phase and incorporated nanosized material. An innovative analytical approach for the determination of the physical stability of the emulsion under investigation is presented. Advantages and limitations of the employed analytical imaging techniques are highlighted. PMID:24300401

  4. Effect of Particle Size on the Photocatalytic Activity of Nanoparticulate Zinc Oxide

    Microsoft Academic Search

    A. C. Dodd; A. J. McKinley; M. Saunders; T. Tsuzuki

    2006-01-01

    In this study, a three-stage process consisting of mechanical milling, heat treatment, and washing has been used to manufacture\\u000a nanoparticulate ZnO powders with a controlled particle size and minimal agglomeration. By varying the temperature of the post-milling\\u000a heat treatment, it was possible to control the average particle size over the range of 28–57 nm. The photocatalytic activity\\u000a of these powders was

  5. NCL supports the first biocompatible NIST nanoparticulate reference material - Nanotechnology Characterization Laboratory

    Cancer.gov

    In late December 2007, the National Institute of Standards and Technology (NIST) released its first reference standards for nanoscale particles targeted for the biomedical research community. The new nanoparticulate reference materials (RMs) consist of colloidal gold nanoparticles with nominal diameters of 10, 30, and 60 nanometers (nm) in suspension. Production of these RMs was supported in part by the National Cancer Institute (NCI) Alliance for Nanotechnology in Cancer and the Nanotechnology Characterization Laboratory (NCL) at NCI-Frederick.

  6. Electrodeposition of mesoscopic Pt-Ru on reticulated vitreous carbon from reverse emulsions and microemulsions: Application to methanol electro-oxidation

    Microsoft Academic Search

    Tommy T. Cheng; El?d L. Gyenge

    2006-01-01

    High surface area Pt-Ru (between 120 and 400cm2mg?1) meso-sized particles and mesoporous coatings were electrodeposited on reticulated vitreous carbon (RVC) three-dimensional electrodes using reverse emulsions and microemulsions. The organic phase of the colloidal media was composed of cyclohexane, Triton X-100 non-ionic surfactant and tetrabutylammonium perchlorate (for ionic conductivity) while the aqueous phase contained H2PtCl6 and RuCl3 (or (NH4)2RuCl6). For microemulsification

  7. Novel anode catalyst for direct methanol fuel cells.

    PubMed

    Basri, S; Kamarudin, S K; Daud, W R W; Yaakob, Z; Kadhum, A A H

    2014-01-01

    PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs) but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni) and iron (Fe). Multiwalled carbon nanotubes (MWCNTs) are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV) is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA) tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR). The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2-5 nm) PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g(-1) catalyst. PMID:24883406

  8. Mo oxide modified catalysts for direct methanol, formaldehydeand formic acid fuel cells

    Microsoft Academic Search

    Chaojie Song; Mohammad Khanfar; Peter G. Pickup

    2006-01-01

    Pt black and PtRu black fuel cell anodes have been modified with Mo oxide and evaluated in direct methanol, formaldehyde and\\u000a formic acid fuel cells. Mo oxide deposition by reductive electrodeposition from sodium molybdate or by spraying of the fuel\\u000a cell anode with aqueous sodium molybdate resulted in similar performance gains in formaldehyde cells. At current densities\\u000a below ca. 20 mA cm?2,

  9. MgO-Supported Cluster Catalysts with Pt-Ru Interactions Prepared from Pt3Ru6(CO)21(u3-H)(u-H)3

    SciTech Connect

    Chotisuwan,S.; Wittapyakun, J.; Lobo-Lapidus, R.; Gates, B.

    2007-01-01

    Bimetallic MgO-supported catalysts were prepared by adsorption of Pt{sub 3}Ru{sub 6}(CO){sub 21}({mu}{sub 3}-H)({mu}-H){sub 3} on porous MgO. Characterization of the supported clusters by infrared (IR) spectroscopy showed that the adsorbed species were still in the form of metal carbonyls. The supported clusters were decarbonylated by treatment in flowing helium at 300 C, as shown by IR and extended X-ray absorption fine structure (EXAFS) data, and the resulting supported PtRu clusters were shown by EXAFS spectroscopy to have metal frames that retained Pt-Ru bonds but were slightly restructured relative to those of the precursor; the average cluster size was almost unchanged as a result of the decarbonylation. These are among the smallest reported bimetallic clusters of group-8 metals. The decarbonylated sample catalyzed ethylene hydrogenation with an activity similar to that reported previously for {gamma}-Al{sub 2}O{sub 3}-supported clusters prepared in nearly the same way and having nearly the same structure. Both samples were also active for n-butane hydrogenolysis, with the MgO-supported catalyst being more active than the {gamma}-Al{sub 2}O{sub 3}-supported catalyst.

  10. Biogenic nanoparticulate UO 2: Synthesis, characterization, and factors affecting surface reactivity

    NASA Astrophysics Data System (ADS)

    Singer, David M.; Farges, François; Brown, Gordon E., Jr.

    2009-06-01

    The surface reactivity of biogenic, nanoparticulate UO 2 with respect to sorption of aqueous Zn(II) and particle annealing is different from that of bulk uraninite because of the presence of surface-associated organic matter on the biogenic UO 2. Synthesis of biogenic UO 2 was accomplished by reduction of aqueous uranyl ions, UO22+ by Shewanella putrefaciens CN32, and the resulting nanoparticles were washed using one of two protocols: (1) to remove surface-associated organic matter and soluble uranyl species (NAUO2), or (2) to remove only soluble uranyl species (BIUO2). A suite of bulk and surface characterization techniques was used to examine bulk and biogenic, nanoparticulate UO 2 as a function of particle size and surface-associated organic matter. The N 2-BET surface areas of the two biogenic UO 2 samples following the washing procedures are 128.63 m 2 g -1 (NAUO2) and 92.56 m 2 g -1 (BIUO2), and the average particle sizes range from 5-10 nm based on TEM imaging. Electrophoretic mobility measurements indicate that the surface charge behavior of biogenic, nanoparticulate UO 2 (both NAUO2 and BIUO2) over the pH range 3-9 is the same as that of bulk. The U L III-edge EXAFS spectra for biogenic UO 2 (both NAUO2 and BIUO2) were best fit with half the number of second-shell uranium neighbors compared to bulk uraninite, and no oxygen neighbors were detected beyond the first shell around U(IV) in the biogenic UO 2. At pH 7, sorption of Zn(II) onto both bulk uraninite and biogenic, nanoparticulate UO 2 is independent of electrolyte concentration, suggesting that Zn(II) sorption complexes are dominantly inner-sphere. The maximum surface area-normalized Zn(II) sorption loadings for the three substrates were 3.00 ± 0.20 ?mol m -2 UO 2 (bulk uraninite), 2.34 ± 0.12 ?mol m -2 UO 2 (NAUO2), and 2.57 ± 0.10 ?mol m -2 UO 2 (BIUO2). Fits of Zn K-edge EXAFS spectra for biogenic, nanoparticulate UO 2 indicate that Zn(II) sorption is dependent on the washing protocol. Zn-U pair correlations were observed at 2.8 ± 0.1 Å for NAUO2 and bulk uraninite; however, they were not observed for sample BIUO2. The derived Zn-U distance, coupled with an average Zn-O distance of 2.09 ± 0.02 Å, indicates that Zn(O,OH) 6 sorbs as bidentate, edge-sharing complexes to UO 8 polyhedra at the surface of NAUO2 nanoparticles and bulk uraninite, which is consistent with a Pauling bond-valence analysis. The absence of Zn-U pair correlations in sample BIUO2 suggests that Zn(II) binds preferentially to the organic matter coating rather than the UO 2 surface. Surface-associated organic matter on the biogenic UO 2 particles also inhibited particle annealing at 90 °C under anaerobic conditions. These results suggest that surface-associated organic matter decreases the reactivity of biogenic, nanoparticulate UO 2 surfaces relative to aqueous Zn(II) and possibly other environmental contaminants.

  11. Oral Nanoparticulate Atorvastatin Calcium is More Efficient and Safe in Comparison to Lipicure ® in Treating Hyperlipidemia

    Microsoft Academic Search

    A. K. Meena; D. Venkat Ratnam; G. Chandraiah; D. D. Ankola; P. Rama Rao; M. N. V. Ravi Kumar

    2008-01-01

    Atorvastatin calcium (AC) is a second-generation 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor approved for clinical\\u000a use as a lipid lowering agent. AC, the world’s best selling drug is associated with poor oral bioavailability and serious\\u000a adverse effects like rhabdomyolysis on chronic administration. A biodegradable nanoparticulate approach was introduced here\\u000a with a view to improving the efficacy and safety of AC. Poly lactide-co-glycolic acid

  12. Rate-programming of nano-particulate delivery systems for smart bioactive scaffolds in tissue engineering

    NASA Astrophysics Data System (ADS)

    Izadifar, Mohammad; Haddadi, Azita; Chen, Xiongbiao; Kelly, Michael E.

    2015-01-01

    Development of smart bioactive scaffolds is of importance in tissue engineering, where cell proliferation, differentiation and migration within scaffolds can be regulated by the interactions between cells and scaffold through the use of growth factors (GFs) and extra cellular matrix peptides. One challenge in this area is to spatiotemporally control the dose, sequence and profile of release of GFs so as to regulate cellular fates during tissue regeneration. This challenge would be addressed by rate-programming of nano-particulate delivery systems, where the release of GFs via polymeric nanoparticles is controlled by means of the methods of, such as externally-controlled and physicochemically/architecturally-modulated so as to mimic the profile of physiological GFs. Identifying and understanding such factors as the desired release profiles, mechanisms of release, physicochemical characteristics of polymeric nanoparticles, and externally-triggering stimuli are essential for designing and optimizing such delivery systems. This review surveys the recent studies on the desired release profiles of GFs in various tissue engineering applications, elucidates the major release mechanisms and critical factors affecting release profiles, and overviews the role played by the mathematical models for optimizing nano-particulate delivery systems. Potentials of stimuli responsive nanoparticles for spatiotemporal control of GF release are also presented, along with the recent advances in strategies for spatiotemporal control of GF delivery within tissue engineered scaffolds. The recommendation for the future studies to overcome challenges for developing sophisticated particulate delivery systems in tissue engineering is discussed prior to the presentation of conclusions drawn from this paper.

  13. The Science Behind Nanosun-Screens: Learning about Nanoparticulate Ingredients Used to Block the Sun's Ultraviolet Rays

    ERIC Educational Resources Information Center

    Wise, Alyssa; Schank, Patricia; Stanford, Tina; Horsma, Geri

    2009-01-01

    In this article, the authors provide a brief overview of the emerging field of nanoscience and why it is an important area of education. They next explain the science behind the new nanoparticulate sunscreens, describe the different elements of the unit, and reflect on some of the opportunities and challenges of teaching nanoscience at the high…

  14. Variations in interfacial properties during cell conditioning and influence of heat-treatment of ionomer on the characteristics of direct methanol fuel cells

    Microsoft Academic Search

    Fuqiang Liu; Chao-Yang Wang

    2005-01-01

    Variations in interfacial properties in the anode catalyst layer during cell conditioning were characterized, and influence of the heat-treatment of ionomer on the characteristics of direct methanol fuel cells was investigated in this work. The anode catalyst layer was made by mixing a solvent-substituted Nafion solution with unsupported Pt\\/Ru black and curing the mixture in an oven with an inert

  15. Systematic Modulation of Quantum (Electron) Tunneling Behavior by Atomic Layer Deposition on Nanoparticulate SnO2 and TiO2

    E-print Network

    , such as the nanoparticulate and semiconducting photoanode of a dye-sensitized solar cell (DSC), with a layer of a second metal. Hupp*,, Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center

  16. Net methylation of mercury in estuarine sediment microcosms amended with dissolved, nanoparticulate, and microparticulate mercuric sulfides.

    PubMed

    Zhang, Tong; Kucharzyk, Katarzyna H; Kim, Bojeong; Deshusses, Marc A; Hsu-Kim, Heileen

    2014-08-19

    The production of methylmercury (MeHg) by anaerobic microorganisms depends in part on the speciation and bioavailability of inorganic mercury to these organisms. Our previous work with pure cultures of methylating bacteria has demonstrated that the methylation potential of mercury decreased during the aging of mercuric sulfides (from dissolved to nanoparticulate and microcrystalline HgS). The objective of this study was to understand the relationship between mercury sulfide speciation and methylation potential in experiments that more closely simulate the complexity of sediment settings. The study involved sediment slurry microcosms that represented a spectrum of salinities in an estuary and were each amended with different forms of mercuric sulfides: dissolved Hg and sulfide, nanoparticulate HgS (3-4 nm in diameter), and microparticulate HgS (>500 nm). The results indicated that net MeHg production was influenced by both the activity of sulfate-reducing microorganisms (roughly represented by the rate of sulfate loss) and the bioavailability of mercury. In the presence of abundant sulfate and carbon sources (supporting relatively high microbial activity), net MeHg production in the slurries amended with dissolved Hg was greater than in slurries amended with nano-HgS, similar to previous experiments with pure bacterial cultures. In microcosms with minimal microbial activity (indicated by low rates of sulfate loss), the addition of either dissolved Hg or nano-HgS resulted in similar amounts of net MeHg production. For all slurries receiving micro-HgS, MeHg production did not exceed abiotic controls. In slurries amended with dissolved and nano-HgS, mercury was mainly partitioned to bulk-scale mineral particles and colloids, indicating that Hg bioavailability was not simply related to dissolved Hg concentration or speciation. Overall, the results suggest that models for mercury methylation potential in the environment will need to balance the relative contributions of mercury speciation and activity of methylating microorganisms. PMID:25007388

  17. In vitro and in vivo evaluation of a nanoparticulate bioceramic paste for dental pulp repair.

    PubMed

    Zhu, Lingxin; Yang, Jingwen; Zhang, Jie; Lei, Dongqi; Xiao, Lan; Cheng, Xue; Lin, Ying; Peng, Bin

    2014-12-01

    Bioactive materials play an important role in facilitating dental pulp repair when living dental pulp is exposed after injuries. Mineral trioxide aggregate is the currently recommended material of choice for pulp repair procedures though has several disadvantages, especially the inconvenience of handling. Little information is yet available about the early events and molecular mechanisms involved in bioceramic-mediated dental pulp repair. We aimed to characterize and determine the apatite-forming ability of the novel ready-to-use nanoparticulate bioceramic iRoot BP Plus, and investigate its effects on the in vitro recruitment of human dental pulp stem cells (DPSCs), as well as its capacity to induce dentin bridge formation in an in vivo model of pulp repair. It was found that iRoot BP Plus was nanosized and had excellent apatite-forming ability in vitro. Treatment with iRoot BP Plus extracts promoted the adhesion, migration and attachment of DPSCs, and optimized focal adhesion formation (Vinculin, p-Paxillin and p-Focal adhesion kinase) and stress fibre assembly. Consistent with the in vitro results, we observed the formation of a homogeneous dentin bridge and the expression of odontogenic (dentin sialoprotein, dentin matrix protein 1) and focal adhesion molecules (Vinculin, p-Paxillin) at the injury site of pulp repair model by iRoot BP Plus. Our findings provide valuable insights into the mechanism of bioceramic-mediated dental pulp repair, and the novel revolutionary ready-to-use nanoparticulate bioceramic paste shows promising therapeutic potential in dental pulp repair application. PMID:25182220

  18. In situ Fourier transform infrared-diffuse reflection spectroscopy of direct methanol fuel cell anodes and cathodes

    SciTech Connect

    Fan, Q.; Pu, C.; Smotkin, E.S. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical and Environmental Engineering

    1996-10-01

    In situ Fourier transform infrared-diffuse reflection spectroscopy (FTIR-DRS) was used to study both the adsorbed and desorbed species produced on high surface area anodes and cathodes of direct methanol/oxygen fuel cells. The authors investigated platinum-ruthenium and platinum black as anodes. The cathodes studied were platinum black. The primary product detected on both Pt-black and Pt-Ru anodes at low methanol/water vapor ratios (P{sub methanol}: 15.2 kPa) was CO{sub 2}. Consistent with previous work, CO adsorption is more prevalent on Pt-black than on Pt-RU. In addition to CO and CO{sub 2}, vibrational modes due to formic acid, methylformate, and formaldehyde are detected by FTIR-DRS under potentiostatic control. At higher methanol/water vapor ratios (P{sub methanol}: 38.0 kPa) and low potentials (0.10 to 0.50 V), formaldehyde is the only product at the Pt-Ru anode. Methylformate and formic acid vibrational modes appear at potentials from 0.60 to 0.80 V. CO{sub 2} and methanol are observed at open circuit on the cathode side as a result of methanol permeation from the anode to the cathode region. CO{sub 2} increases in the cathode region with increasing anode potential.

  19. Particle-Level Modeling of the Charge-Discharge Behavior of Nanoparticulate Phase-Separating Li-Ion Battery Electrodes

    E-print Network

    Orvananos, Bernardo; Yu, Hui-Chia; Bazant, Martin Z; Thornton, Katsuyo

    2013-01-01

    In nanoparticulate phase-separating electrodes, phase separation inside the particles can be hindered during their charge/discharge cycles even when a thermodynamic driving force for phase separation exists. In such cases, particles may (de)lithiate discretely in a process referred to as mosaic instability. This instability could be the key to elucidating the complex charge/discharge dynamics in nanoparticulate phase-separating electrodes. In this paper, the dynamics of the mosaic instability is studied using Smoothed Boundary Method simulations at the particle level, where the concentration and electrostatic potential fields are spatially resolved around individual particles. Two sets of configurations consisting of spherical particles with an identical radius are employed to study the instability in detail. The effect of an activity-dependent exchange current density on the mosaic instability, which leads to asymmetric charge/discharge, is also studied. While we show that our model reproduces the results of...

  20. Innovative application of ultrasonic mixing to produce homogeneously mixed nanoparticulate-epoxy composite of improved physical properties

    Microsoft Academic Search

    M. S. Goyat; S. Ray; P. K. Ghosh

    2011-01-01

    An innovative ultrasonic dual mixing process (ultrasonic mixing along with impeller stirring) has been employed to disperse round Al2O3 (<25nm) particles in epoxy resin. Characterization of the nanoparticulate-epoxy composite has been carried out using TEM, AFM, DTA, TGA and FTIR and compared with the results obtained in epoxy without particles. When epoxy is treated by this dual mixing there is

  1. Self-directing organometallic deposition of ruthenium: Preparation, characterization and evaluation of bimetallic, ruthenium adatom modified platinum surfaces for the electrooxidation of methanol in direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, Christopher Edward

    State of the art direct methanol fuel cells use Pt-Ru particles as anode electrocatalysts for the oxidation of methanol. There are two longstanding difficulties with evaluating such catalysts; first, there are no proven methods to measure their specific surface areas (number of active sites); and second, there are no proven methods to measure the surface ratio of Pt to Ru on black (rough) Pt-Ru surfaces or particles. Further, the reported methods to prepare such catalysts do not have demonstrable control over these parameters, and surface segregation may occur during the high temperature stages of the preparation. As a result of these difficulties, the optimum surface composition and chemical state of such catalysts is still under investigation nearly 40 years after their discovery. An organometallic chemistry approach to this problem was chosen. It was found that black Pt (as a gauze or as a powder) effects the hydrogenation (1 atm, -40°C, in hexanes) of (1,5-cyclooctadiene)Ru(C 3H5)2 to result in Ru adatoms (Ruad) adsorbed by the Pt surface and the concomitant formation of cyclooctane and propane. By monitoring the reaction at low temperatures using gas chromatography or UV-Vis spectrophotometry, real time control over both the number of surface equivalents of Ruad deposited on Pt, and over the activity of the resulting Pt-Ruad surfaces was realized. This reaction was used to prepare a series of blacked Pt-Ruad gauzes and black Pt-Ru ad powders of reasonably defined surface areas and surface compositions. The activities of these gauzes and powders towards the electrooxidation of methanol under typical operating conditions for a direct methanol fuel cell were determined. Remarkably, the black Pt-Ruad powders were stable towards hot pressing into NafionRTM membranes and towards use in prototype direct methanol fuel cells operating at 90°C. The optimum surface composition for operation in direct methanol fuel cells under these conditions was determined.

  2. Characterization and ecological risk assessment of nanoparticulate CeO2 as a diesel fuel catalyst.

    PubMed

    Batley, Graeme E; Halliburton, Brendan; Kirby, Jason K; Doolette, Casey L; Navarro, Divina; McLaughlin, Mike J; Veitch, Colin

    2013-08-01

    Nanoparticulate cerium dioxide (nano-CeO2 ), when combusted as an additive to diesel fuel, was transformed from 6?nm to 14?nm sizes into particles near 43?nm, with no obvious change in the unit cell dimensions or crystalline form. Cerium sulfate, if formed during combustion, was below detection limits. Ceria nanoparticles were agglomerated within the soot matrix, with a mean aerodynamic diameter near 100?nm. The dissolution of cerium from the dried ceria catalyst in synthetic soft water was extremely small (<0.0006% or <0.2?µg Ce/L), with particles being highly agglomerated (<450?nm). Agglomeration was reduced in the presence of humic acid. In the combusted samples, soot was dominant, and the solubility of cerium in soft water showed an almost 100-fold increase in the <1?nm fraction compared to that before combustion. It appeared that the nano-CeO2 remained agglomerated within the soot matrix and would not be present as dispersed nanoparticles in aquatic or soil environments. Despite the increased dissolution, the solubility was not sufficient for the combusted ceria to represent a risk in aquatic ecosystems. The predicted environmental concentrations were still orders of magnitude below the predicted no effects concentration of near 1?mg/L. In the soil environment, any cerium released from soot materials would interact with natural colloids, decreasing cerium concentrations in soil solutions and further minimizing the potential risk to soil organisms. PMID:23595783

  3. A novel nanoparticulate system for sustained delivery of acid-labile lansoprazole.

    PubMed

    Alai, Milind Sadashiv; Lin, Wen Jen

    2013-11-01

    In the present study, an effort was made to develop the Eudragit RS100 based nanoparticulate system for sustained delivery of an acid-labile drug, lansoprazole (LPZ). LPZ-loaded Eudragit RS100 nanoparticles (ERSNPs) were prepared by oil-in-water emulsion-solvent evaporation method. The effects of various formulation variables such as polymer concentration, drug amount and solvent composition on physicochemical performance of nanoparticles and in vitro drug release were investigated. All nanoparticles were spherical with particle size 198.9 ± 8.6-376.9 ± 5.6 nm and zeta potential +35.1 ± 1.7 to +40.2 ± 0.8 mV. The yield of nanoparticles was unaffected by change of these three variables. However, the drug loading and encapsulation efficiency were affected by polymer concentration and drug amount. On the other hand, the particle size of nanoparticles was significantly affected by polymer concentration and internal phase composition due to influence of droplet size during emulsification process. All nanoparticles prolonged drug release for 24h which was dominated by a combination of drug diffusion and polymer chain relaxation. The fastest and the slowest release rates were observed in C2-1002-10/0 and C8-4001-10/0, respectively, based on the release rate constant (k). Thus, the developed nanoparticles possessed a potential as a nano-carrier to sustain drug delivery for treatment of acid related disorders. PMID:23867305

  4. Effects of ZnO nanoparticulate addition on the properties of PMNT ceramics

    PubMed Central

    2012-01-01

    This research was conducted in order to study the effect of ZnO nanoparticulate addition on the properties of 0.9 Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 [PMNT] ceramics. The PMNT ceramics were prepared by a solid-state reaction. The ZnO nanoparticles were added into PMNT ceramics to form PMNT/xZnO (x = 0, 0.05, 0.1, 0.5, and 1.0 wt.%). The PMNT/xZnO ceramics were investigated in terms of phase, microstructure, and mechanical and electrical properties. It was found that the density and grain size of PMNT ceramics tended to increase with an increasing amount of ZnO content. Moreover, a transgranular fracture was observed for the samples containing ZnO, while pure PMNT ceramics showed only a intergranular fracture. An addition of only 0.05 wt.% of ZnO was also found to enhance the hardness and dielectric and ferroelectric properties of the PMNT ceramics. PMID:22222049

  5. Effects of ZnO nanoparticulate addition on the properties of PMNT ceramics.

    PubMed

    Promsawat, Methee; Watcharapasorn, Anucha; Jiansirisomboon, Sukanda

    2012-01-01

    This research was conducted in order to study the effect of ZnO nanoparticulate addition on the properties of 0.9 Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 [PMNT] ceramics. The PMNT ceramics were prepared by a solid-state reaction. The ZnO nanoparticles were added into PMNT ceramics to form PMNT/xZnO (x = 0, 0.05, 0.1, 0.5, and 1.0 wt.%). The PMNT/xZnO ceramics were investigated in terms of phase, microstructure, and mechanical and electrical properties. It was found that the density and grain size of PMNT ceramics tended to increase with an increasing amount of ZnO content. Moreover, a transgranular fracture was observed for the samples containing ZnO, while pure PMNT ceramics showed only a intergranular fracture. An addition of only 0.05 wt.% of ZnO was also found to enhance the hardness and dielectric and ferroelectric properties of the PMNT ceramics. PMID:22222049

  6. Kinetically Controlled Formation of a Novel Nanoparticulate ZnS with Mixed Cubic and Hexagonal Stacking

    SciTech Connect

    Zhang,H.; Chen, B.; Gilbert, B.; Banfield, J.

    2006-01-01

    Nanoparticulate ZnS with mixed cubic and hexagonal close packed stacking was synthesized by reaction of zinc acetate with thioacetamide in weakly acidic solutions. The influences of temperature, reaction time, amounts of reagents and solution pH on the nanoparticle size and phase constitution were investigated. Experimental results suggest that the stacking in the nano-ZnS is controlled primarily by the precipitation kinetics. Factors that slow the precipitation rate favor the growth of nanoparticles with mixed stacking, probably because the probabilities of forming wurtzite-like layers and sphalerite-like layers under these conditions are approximately equal. Under conditions of rapid precipitation, the growth of sphalerite is favored, probably due to the aggregation of molecular clusters with sphalerite-like structure. UV-vis spectroscopy reveals that twins and stacking faults in nano-ZnS result in an electronic structure that differs from those of nano-scale sphalerite and wurtzite. New vibrational modes present in IR spectra of the nano-ZnS with mixed stacking indicate that the materials have novel optical properties. Control of defect microstructure may allow use of nano-ZnS in new technological applications.

  7. Transport of polymeric nanoparticulate drug delivery systems in the proximity of silica and sand.

    PubMed

    Chen, I-Cheng; Zhang, Ming; Teipel, Blake; de Araujo, Isa Silveira; Yegin, Yagmur; Akbulut, Mustafa

    2015-03-17

    The contamination of the environment with traditional therapeutics due to metabolic excretion, improper disposal, and industrial waste has been well-recognized. However, knowledge of the environmental distribution and fate of emerging classes of nanomedicine is scarce. This work investigates the effect of surface chemistry of polymeric nanoparticulate drug delivery systems (PNDDS) on their adsorption dynamics and transport in the vicinity of environmentally relevant surfaces for a concentration comparable with hospital and pharmaceutical manufacturing effluents. To this end, five different types of paclitaxel-based nanomedicine having different polymer stabilizers were employed. Their transport behavior was characterized via quartz crystal microbalance, sand column, spectrofluorometry, and dynamic light scattering techniques. PNDDS having positive zeta-potential displayed strong adsorption onto silica surfaces and no mobility in porous media of quartz sand, even in the presence of humic acid. The mobility of negatively charged PNDDS strongly depended on the amount and type of salt present in the aqueous media: Without any salt, such PNDDS demonstrated no adsorption on silica surfaces and high levels of mobility in sand columns. The presence of CaCl2 and CaSO4, even at low ionic strengths (i.e. 10 mM), induced PNDDS adsorption on silica surfaces and strongly limited the mobility of such PNDSS in sand columns. PMID:25695909

  8. An aquaporin 4 antisense oligonucleotide loaded, brain targeted nanoparticulate system design.

    PubMed

    Kozlu, S; Caban, S; Yerlikaya, F; Fernandez-Megia, E; Novoa-Carballal, R; Riguera, R; Yemisci, M; Gursoy-Ozdemir, Y; Dalkara, T; Couvreur, P; Capan, Y

    2014-05-01

    Aquaporins (AQPs), members of the water-channel protein family, are highly expressed in brain tissue especially in astrocytic end-feet. They are important players for water hemostasis during development of cytotoxic as well as vasogenic edema. Increased expression of AQPs is important in pathophysiology of neurological diseases such as neuroinflammation and ischemia. Unfortunately, there are a few pharmacological inhibitors of AQP4 with several side effects limiting their translation as a drug for use in clinical conditions. Another therapeutic approach is using antisense oligonucleotides (ASOs) to block AQP4 activity. These are short, synthetic, modified nucleic acids that bind RNA to modulate its function. However, they cannot pass the blood brain barrier (BBB). To overcome this obstacle we designed a nanoparticulate system made up of chitosan nanoparticles surface modified with PEG and conjugated with monoclonal anti transferrin receptor-1 antibody via streptavidin-biotin binding. The nanocarrier system could be targeted to the transferrin receptor-1 at the brain endothelial capillaries through monoclonal antibodies. It is hypothesized that the nanoparticles could pass the BBB via receptor mediated transcytosis and reach brain parenchyma. Particle size, zeta potential, loading capacity and release profiles of nanoparticles were investigated. It was observed that all types of chitosau (CS) nanoparticles had positive zeta potential values and nanoparticle particle size distribution varied between 100 and 800 nm. The association efficiency of ASOs into the nanoparticles was between 80-97% and the release profiles of the nanoparticles exhibited an initial burst effect followed by a controlled release. The results showed that the designed chitosan based nanocarriers could be a promising carrier system to transport nucleic acid based drugs to brain parenchyma. PMID:24855824

  9. Anticancer efficacy and toxicokinetics of a novel paclitaxel-clofazimine nanoparticulate co-formulation.

    PubMed

    Koot, Dwayne; Cromarty, Duncan

    2015-06-01

    Contemporary chemotherapy is limited by disseminated, resistant cancer. Targeting nanoparticulate drug delivery systems that encapsulate synergistic drug combinations are a rational means to increase the therapeutic index of chemotherapeutics. A lipopolymeric micelle co-encapsulating an in vitro optimized, synergistic fixed-ratio combination of paclitaxel (PTX) and clofazimine (B663) has been developed and called Riminocelles™. The present pre-clinical study investigated the acute toxicity, systemic exposure, repeat dose toxicity and efficacy of Riminocelles in parallel to Taxol® at an equivalent PTX dose of 10 mg/kg. Daily and weekly dosing schedules were evaluated against Pgp-expressing human colon adenocarcinoma (HCT-15) xenografts implanted subcutaneously in athymic mice. Riminocelles produced statistically significant (p

  10. Folate-mediated intracellular drug delivery increases the anticancer efficacy of nanoparticulate formulation of arsenic trioxide

    PubMed Central

    Chen, Haimei; Ahn, Richard; Van den Bossche, Jeroen; Thompson, David H.; O’Halloran, Thomas V.

    2011-01-01

    Arsenic trioxide (As2O3) is a frontline drug for treatment of acute promyelocytic leukemia and is in clinical trials for treatment of other malignancies, including multiple myeloma; however, efforts to expand clinical utility to solid tumors have been limited by toxicity. Nanoparticulate forms of As2O3 encapsulated in 100-nm-scale, folate-targeted liposomes have been developed to lower systematic toxicity and provide a platform for targeting this agent. The resultant arsenic “nanobins” are stable under physiologic conditions but undergo triggered drug release when the pH is lowered to endosomal/lysosomal levels. Cellular uptake and antitumor efficacy of these arsenic liposomes have been evaluated in folate receptor (FR)–positive human nasopharyngeal (KB) and cervix (HeLa) cells, as well as FR-negative human breast (MCF-7) tumor cells through confocal microscopy, inductively coupled plasma mass spectroscopy, and cytotoxicity studies. Uptake of folate-targeted liposomal arsenic by KB cells was three to six times higher than that of free As2O3 or nontargeted liposomal arsenic; the enhanced uptake occurs through folate-mediated endocytosis, leading to a 28-fold increase in cytotoxicity. In contrast, tumor cells with lower FR density on the surface (HeLa and MCF-7) showed much less uptake of the folate-targeted drug and lower efficacy. In cocultures of KB and MCF-7 cells, the folate-targeted arsenic liposomes were exclusively internalized by KB cells, showing high targeting specificity. Our studies further indicate that folate-targeted delivery of As2O3 with coencapsulated nickel(II) ions (as a nontoxic adjuvant) potentiates the As2O3 efficacy in relatively insensitive solid tumor–derived cells and holds the promise of improving drug therapeutic index. PMID:19567824

  11. Methylation of mercury by bacteria exposed to dissolved, nanoparticulate, and microparticulate mercuric sulfides.

    PubMed

    Zhang, Tong; Kim, Bojeong; Levard, Clément; Reinsch, Brian C; Lowry, Gregory V; Deshusses, Marc A; Hsu-Kim, Heileen

    2012-07-01

    The production of the neurotoxic methylmercury in the environment is partly controlled by the bioavailability of inorganic divalent mercury (Hg(II)) to anaerobic bacteria that methylate Hg(II). In sediment porewater, Hg(II) associates with sulfides and natural organic matter to form chemical species that include organic-coated mercury sulfide nanoparticles as reaction intermediates of heterogeneous mineral precipitation. Here, we exposed two strains of sulfate-reducing bacteria to three forms of inorganic mercury: dissolved Hg and sulfide, nanoparticulate HgS, and microparticulate HgS. The bacteria cultures exposed to HgS nanoparticles methylated mercury at a rate slower than cultures exposed to dissolved forms of mercury. However, net methylmercury production in cultures exposed to nanoparticles was 6 times greater than in cultures treated with microscale particles, even when normalized to specific surface area. Furthermore, the methylation potential of HgS nanoparticles decreased with storage time of the nanoparticles in their original stock solution. In bacteria cultures amended with nano-HgS from a 16 h-old nanoparticle stock, 6-10% of total mercury was converted to methylmercury after one day. In contrast, 2-4% was methylated in cultures amended with nano-HgS that was aged for 3 days or 1 week. The methylation of mercury derived from nanoparticles (in contrast to the larger particles) would not be predicted by equilibrium speciation of mercury in the aqueous phase (<0.2 ?m) and was possibly caused by the disordered structure of nanoparticles that facilitated release of chemically labile mercury species immediately adjacent to cell surfaces. Our results add new dimensions to the mechanistic understanding of mercury methylation potential by demonstrating that bioavailability is related to the geochemical intermediates of rate-limited mercury sulfide precipitation reactions. These findings could help explain observations that the "aging" of mercury in sediments reduces its methylation potential and provide a basis for assessing and remediating methylmercury hotspots in the environment. PMID:22145980

  12. K-edge ratio method for identification of multiple nanoparticulate contrast agents by spectral CT imaging

    PubMed Central

    Ghadiri, H; Ay, M R; Shiran, M B; Soltanian-Zadeh, H

    2013-01-01

    Objective: Recently introduced energy-sensitive X-ray CT makes it feasible to discriminate different nanoparticulate contrast materials. The purpose of this work is to present a K-edge ratio method for differentiating multiple simultaneous contrast agents using spectral CT. Methods: The ratio of two images relevant to energy bins straddling the K-edge of the materials is calculated using an analytic CT simulator. In the resulting parametric map, the selected contrast agent regions can be identified using a thresholding algorithm. The K-edge ratio algorithm is applied to spectral images of simulated phantoms to identify and differentiate up to four simultaneous and targeted CT contrast agents. Results: We show that different combinations of simultaneous CT contrast agents can be identified by the proposed K-edge ratio method when energy-sensitive CT is used. In the K-edge parametric maps, the pixel values for biological tissues and contrast agents reach a maximum of 0.95, whereas for the selected contrast agents, the pixel values are larger than 1.10. The number of contrast agents that can be discriminated is limited owing to photon starvation. For reliable material discrimination, minimum photon counts corresponding to 140?kVp, 100?mAs and 5-mm slice thickness must be used. Conclusion: The proposed K-edge ratio method is a straightforward and fast method for identification and discrimination of multiple simultaneous CT contrast agents. Advances in knowledge: A new spectral CT-based algorithm is proposed which provides a new concept of molecular CT imaging by non-iteratively identifying multiple contrast agents when they are simultaneously targeting different organs. PMID:23934964

  13. Nanospray technology for an in situ gelling nanoparticulate powder as a wound dressing.

    PubMed

    De Cicco, Felicetta; Porta, Amalia; Sansone, Francesca; Aquino, Rita P; Del Gaudio, Pasquale

    2014-10-01

    In the current study the feasibility of the novel nano spray drying technique for the production of stable nanoparticulate dry powder, able to gel when administered locally on a wound, is explored. Gentamicin sulphate (GS) was loaded into alginate/pectin nanoparticles as highly soluble (hygroscopic) model drug with wide range antibacterial agent for wound dressing. The influence of process variables, mainly spray mesh size and feed concentration, on particle size and morphology, powder wound fluid uptake ability and gelling rate, as well as hydrogel water vapour transmission at wound site were studied. Particles morphology was spherical with few exceptions as slightly corrugated particles when the larger nozzle was used. Production of spherical nanoparticles (d50 ? 350 nm) in good yield (82-92%) required 4 ?m spray mesh whereas 7 ?m mesh produced larger wrinkled particles. Nano spray-dried particles showed high encapsulation efficiency (? 80%), good flowability, high fluid uptake, fast gel formation (15 min) and proper adhesiveness to fill the wound site and to remove easily the formulation after use. Moreover, moisture transmission of the in situ formed hydrogel was between 95 and 90 g/m(2)/h, an optimum range to avoid wound dehydration or occlusion phenomena. Release of the encapsulated GS, monitored as permeation rate using Franz cells in simulated wound fluid (SWF) was related to particle size and gelling rate. Sustained permeation profiles were obtained achieving total permeation of the drug between 3 and 6 days. However, all nano spray-dried formulations presented a burst effect, suitable to prevent infection spreading at the beginning of the therapy. Antimicrobial tests against Staphylococcus aureus and Pseudomonas aeruginosa showed stronger and prolonged antimicrobial effect of the nanoparticles compared to pure GS both shortly after administration and over time (till 12 days). PMID:24979533

  14. Development and characterization of polymeric nanoparticulate delivery system for hydrophillic drug: Gemcitabine

    NASA Astrophysics Data System (ADS)

    Khurana, Jatin

    Gemcitabine is a nucleoside analogue, used in various carcinomas such as non small cell lung cancer, pancreatic cancer, ovarian cancer and breast cancer. The major setbacks to the conventional therapy with gemcitabine include its short half-life and highly hydrophilic nature. The objectives of this investigation were to develop and evaluate the physiochemical properties, drug loading and entrapment efficiency, in vitro release, cytotoxicity, and cellular uptake of polymeric nano-particulate formulations containing gemcitabine hydrochloride. The study also entailed development and validation of a high performance liquid chromatography (HPLC) method for the analysis of gemcitabine hydrochloride. A reverse phase HPLC method using a C18 Luna column was developed and validated. Alginate and Poly lactide co glycolide/Poly-epsilon-caprolactone (PLGA:PCL 80:20) nanoparticles were prepared by multiple emulsion-solvent evaporation methodology. An aqueous solution of low viscosity alginate containing gemcitabine was emulsified into 10% solution of dioctyl-sulfosuccinate in dichloro methane (DCM) by sonication. The primary emulsion was then emulsified in 0.5% (w/v) aqueous solution of polyvinyl alcohol (PVA). Calcium chloride solution (60% w/v) was used to cause cross linking of the polymer. For PLGA:PCL system, the polymer mix was dissolved in dichloromethane (DCM) and an aqueous gemcitabine (with and without sodium chloride) was emulsified under ultrasonic conditions (12-watts; 1-min). This primary emulsion was further emulsified in 2% (w/v) PVA under ultrasonic conditions (24-watts; 3-min) to prepare a multiple-emulsion (w/o/w). In both cases DCM, the organic solvent was evaporated (20- hours, magnetic-stirrer) prior to ultracentrifugation (10000-rpm for PLGA:PCL; 25000-rpm for alginate). The pellet obtained was washed thrice with de-ionized water to remove PVA and any free drug and re-centrifuged. The particles were re-suspended in de-ionized water and then lyophilized to obtain the dried powdered delivery formulation. Particle size and surface charge of the nano-particles were measured using zeta-sizer. The surface morphology and microstructure were evaluated by scanning electron microscopy The drug loading and entrapment efficiencies were evaluated by a HPLC method (Luna C18 column (4.6 X 250 mm), 95/5 (v/v) 0.04M ammonium acetate/acetonitrile mobile phase (pH 5.5), 1.0 ml/min flow rate and 268 nm UV detection). Differential scanning calorimetry (DSC) was used to determine the physical state of gemcitabine in the nanoparticles. The cytotoxicity in pancreatic cancer cells (BxPC-3) was evaluated by MTT assay. The cellular uptake of gemcitabine solution and gemcitabine loaded alginate nano-particle suspension in BxPC-3 cells was determined for 15, 30 and 60 minutes. The particle-size and surface-charge was 564.7+/-56.5nm and -25.65+/-1.94mV for PLGA:PCL and 210.6+/-6.90nm and -33.21+/-1.63mV for alginate. Both the nano-particles were distinctly spherical and non-porous. The drug load was 5.14% for PLGA:PCL and 6.87% for alginate-particles, and the practical entrapment efficiency was found to be 54.1 % and 22.4% respectively. However, in case of PLGA:PCL particles, a two-fold increase in the entrapment efficiency was observed with the addition of sodium-chloride. The absence of endothermic melting peak of the drug in the DSC thermogram was an indication of the non-crystalline state of gemcitabine in the nanoparticles. In addition, there was no cytotoxicity associated with nanoparticle concentrations at-or-below 5 mg/mL. The uptake of nano-particles was around 4 times higher than the solution with treatment for 15 minutes and increased to almost 7 times following treatment for 60 minutes. Gemcitabine hydrochloride could be successfully formulated into a sustained release nano-particulate formulation using calcium cross-linked alginate and dioctyl sulfo succinate system. The nano-particulate delivery system exhibited better cytotoxic activity and also significantly enhanced the accumulation of the drug in BxPC-3 cell monolayers.

  15. Polyelectrolyte-mediated assembly of copper-phthalocyanine tetrasulfonate multilayers and the subsequent production of nanoparticulate copper oxide thin films.

    PubMed

    Chickneyan, Zarui Sara; Briseno, Alejandro L; Shi, Xiangyang; Han, Shubo; Huang, Jiaxing; Zhou, Feimeng

    2004-07-01

    An approach to producing films of nanometer-sized copper oxide particulates, based on polyelectrolyte-mediated assembly of the precursor, copper(II)phthalocyanine tetrasulfonate (CPTS), is described. Multilayered CPTS and polydiallyldimethylammonium chloride (PDADMAC) were alternately assembled on different planar substrates via the layer-by-layer (LbL) procedure. The growth of CPTS multilayers was monitored by UV-visible spectrometry and quartz crystal microbalance (QCM) measurements. Both the UV-visible spectra and the QCM data showed that a fixed amount of CPTS could be attached to the substrate surface for a given adsorption cycle. Cyclic voltammograms at the CPTS/PDADMAC-covered gold electrode exhibited a decrease in peak currents with the layer number, indicating that the permeability of CPTS multilayers on the electrodes had diminished. When these CPTS multilayered films were calcined at elevated temperatures, uniform thin films composed of nanoparticulate copper oxide could be produced. Ellipsometry showed that the thickness of copper oxide nanoparticulate films could be precisely tailored by varying the thickness of CPTS multilayer films. The morphology and roughness of CPTS multilayer and copper oxide thin films were characterized by atomic force microscopy. X-ray diffraction (XRD) measurements indicated that these thin films contained both CuO and Cu2O nanoparticles. The preparation of such copper oxide thin films with the use of metal complex precursors represents a new route for the synthesis of inorganic oxide films with a controlled thickness. PMID:15518398

  16. Particulate Emissions from the Combustion of Diesel Fuel with a Fuel-Borne Nanoparticulate Cerium Catalyst

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Willis, R. D.; Weinstein, J. P.; Krantz, T.; King, C.

    2013-12-01

    To address the adverse impacts on health and climate from the use of diesel-fueled vehicles, a number of technological solutions have been developed for reducing diesel soot emissions and to improve fuel economy. One such solution is the use fuel-borne metal oxide catalysts. Of current interest are commercially-available fuel additives consisting of nanoparticulate cerium oxide (CeO2). In response to the possible use of CeO2-containing fuels in on-road vehicles in the U.S., the Environmental Protection Agency is conducting research to address the potential toxicity and environmental effects of particulate CeO2 emitted with diesel soot. In this study, emissions from a diesel-fueled electric generator were size-segregated on polished silicon wafers in a nanoparticle cascade impactor. The diesel fuel contained 10 ppm Ce by weight in the form of crystalline CeO2 nanoparticles 4 nm to 7.5 nm in size. Primary CeO2 nanoparticles were observed in the diesel emissions as well as CeO2 aggregates encompassing a broad range of sizes up to at least 200 nm. We report the characterization of individual particles from the size-resolved samples with focused ion-beam scanning electron microscopy and energy-dispersive x-ray spectroscopy. Results show a dependency between the impactor size range and CeO2 agglomeration state: in the larger size fractions of the impactor (e.g., 560 nm to 1000 nm) CeO2 nanoparticles were predominantly attached to soot particles. In the smaller size fractions of the impactor (e.g., 100 nm to 320 nm), CeO2 aggregates tended to be larger and unattached to soot. The result is important because the deposition of CeO2 nanoparticles attached to soot particles in the lung or on environmental surfaces such as plant tissue will likely present different consequences than the deposition of unagglomerated CeO2 particles. Disclaimer The U.S. Environmental Protection Agency through its Office of Research and Development funded and collaborated in the research described here under Interagency Agreement DW-13-92339401 to National Institute of Standards and Technology. It has been subjected to Agency review and approved for publication.

  17. Photoelectrocatalytic hydrogen production using nanoparticulate titania and a novel Pt/carbon electrocatalyst: The concept of the "Photoelectrocatalytic Leaf"

    NASA Astrophysics Data System (ADS)

    Pop, Lucian-Cristian; Dracopoulos, Vassilios; Lianos, Panagiotis

    2015-04-01

    Photoelectrocatalytic hydrogen production was realized my means of a double electrode carrying photocatalyst and electrocatalyst, deposited side by side on an FTO electrode, acting as a "Photoelectrocatalytic Leaf". As photocatalyst we used plain commercial nanoparticulate titania and as electrocatalyst a conductive carbon film made by a commercial carbon paste enriched with a small quantity of Pt nanoparticles (0.0134 mg/cm2). This quantity of Pt is much smaller than used in other applications and it may be further optimized. Hydrogen was produced in an alkaline environment in the presence of ethanol acting as sacrificial agent. A few variants of electrode geometry were studied in order to set the basic terms for efficient hydrogen production. It was found that optimal electrode geometry necessitates a much larger area for photocatalyst coverage than electrocatalyst and that it is preferable to divide photocatalyst and electrocatalyst areas in alternating zones.

  18. Coal and tire burning mixtures containing ultrafine and nanoparticulate materials induce oxidative stress and inflammatory activation in macrophages.

    PubMed

    Gasparotto, Juciano; Somensi, Nauana; Caregnato, Fernanda F; Rabelo, Thallita K; DaBoit, Kátia; Oliveira, Marcos L S; Moreira, José C F; Gelain, Daniel P

    2013-10-01

    Ultra-fine and nano-particulate materials resulting from mixtures of coal and non-coal fuels combustion for power generation release to the air components with toxic potential. We evaluated toxicological and inflammatory effects at cellular level that could be induced by ultrafine/nanoparticles-containing ashes from burning mixtures of coal and tires from an American power plant. Coal fly ashes (CFA) samples from the combustion of high-S coal and tire-derived fuel, the latter about 2-3% of the total fuel feed, in a 100-MW cyclone utility boiler, were suspended in the cell culture medium of RAW 264.7 macrophages. Cell viability, assessed by MTT reduction, SRB incorporation and contrast-phase microscopy analysis demonstrated that CFA did not induce acute toxicity. However, CFA at 1mg/mL induced an increase of approximately 338% in intracellular TNF-?, while release of this proinflammatory cytokine was increased by 1.6-fold. The expression of the inflammatory mediator CD40 receptor was enhanced by 2-fold, the receptor for advanced glycation endproducts (RAGE) had a 5.7-fold increase and the stress response protein HSP70 was increased nearly 12-fold by CFA at 1mg/mL. Although CFA did not induce cell death, parameters of oxidative stress and reactive species production were found to be altered at several degrees, such as nitrite accumulation (22% increase), DCFH oxidation (3.5-fold increase), catalase (5-fold increase) and superoxide dismutase (35% inhibition) activities, lipoperoxidation (4.2 fold-increase) and sulfhydryl oxidation (40% decrease in free SH groups). The present results suggest that CFA containing ultra-fine and nano-particulate materials from coal and tire combustion may induce sub-chronic cell damage, as they alter inflammatory and oxidative stress parameters at the molecular and cellular levels, but do not induce acute cell death. PMID:23856402

  19. Absence of systemic toxicity in mouse model towards BaTiO3 nanoparticulate based eluate treatment.

    PubMed

    Dubey, Ashutosh Kumar; Thrivikraman, Greeshma; Basu, Bikramjit

    2015-02-01

    One of the existing issues in implant failure of orthopedic biomaterials is the toxicity induced by the fine particles released during long term use in vivo, leading to acute inflammatory response. In developing a new class of piezobiocomposite to mimic the integrated electrical and mechanical properties of bone, bone-mimicking physical properties as well as in vitro cytocompatibility properties have been achieved with spark plasma sintered hydroxyapatite (HA)-barium titanate (BaTiO3) composites. However, the presence of BaTiO3 remains a concern towards the potential toxicity effect. To address this issue, present work reports the first result to conclusively confirm the non-toxic effect of HA-BaTiO3 piezobiocomposite nanoparticulates, in vivo. Twenty BALB/c mice were intra-articularly injected at their right knee joints with different concentrations of HA-BaTiO3 composite of up to 25 mg/ml. The histopathological examination confirmed the absence of any trace of injected particles or any sign of inflammatory reaction in the vital organs, such as heart, spleen, kidney and liver at 7 days post-exposure period. Rather, the injected nanoparticulates were found to be agglomerated in the vicinity of the knee joint, surrounded by macrophages. Importantly, the absence of any systemic toxicity response in any of the vital organs in the treated mouse model, other than a mild local response at the site of delivery, was recorded. The serum biochemical analyses using proinflammatory cytokines (TNF-? and IL-1?) also complimented to the non-immunogenic response to injected particulates. Altogether, the absence of any inflammatory/adverse reaction will open up myriad of opportunities for BaTiO3 based piezoelectric implantable devices in biomedical applications. PMID:25655497

  20. Biomass into chemicals: One pot-base free oxidative esterification of 5-hydroxymethyl-2-furfural into 2,5-dimethylfuroate with gold on nanoparticulated ceria

    Microsoft Academic Search

    O. Casanova; S. Iborra; A. Corma

    2009-01-01

    2,5-Dimethylfuroate (DMF) is a valuable biomass derivative that can replace oil dependent PET polymers. 5-Hydroxymethyl-2-furfural (HMF) has been selectively converted into DMF (99mol% yield) under mild conditions (65–130°C, 10bar O2) in the absence of any base, by using gold nanoparticles on nanoparticulated ceria. The catalyst can be reused several times without any loss of activity or selectivity. The absence of

  1. Do inhaled carbon nanoparticles translocate directly into the circulation in humans?

    Microsoft Academic Search

    Nicholas L. Mills; Nadia Amin; Simon D. Robinson; Atul Anand; John Davies; Dilip Patel; Jesus M. de la Fuente; Flemming R. Cassee; Nicholas A. Boon; William Macnee; Alistair M. Millar; Ken Donaldson; David E. Newby

    2007-01-01

    RATIONALE: Increased exposure to particulate air pollution (PM(10)) is a risk factor for death and hospitalization with cardiovascular disease. It has been suggested that the nanoparticulate component of PM(10) is capable of translocating into the circulation with the potential for direct effects on the vasculature. OBJECTIVE: The study's aim was to determine the extent to which inhaled technetium-99m ((99m)Tc)-labeled carbon

  2. Anti-biofouling polymer-decorated lutetium-based nanoparticulate contrast agents for in vivo high-resolution trimodal imaging.

    PubMed

    Liu, Zhen; Dong, Kai; Liu, Jianhua; Han, Xueli; Ren, Jinsong; Qu, Xiaogang

    2014-06-25

    Nanomaterials have gained considerable attention and interest in the development of novel and high-resolution contrast agents for medical diagnosis and prognosis in clinic. A classical urea-based homogeneous precipitation route that combines the merits of in situ thermal decomposition and surface modification is introduced to construct polyethylene glycol molecule (PEG)-decorated hybrid lutetium oxide nanoparticles (PEG-UCNPs). By utilizing the admirable optical and magnetic properties of the yielded PEG-UCNPs, in vivo up-conversion luminescence and T1 -enhanced magnetic resonance imaging of small animals are conducted, revealing obvious signals after subcutaneous and intravenous injection, respectively. Due to the strong X-ray absorption and high atomic number of lanthanide elements, X-ray computed-tomography imaging based on PEG-UCNPs is then designed and carried out, achieving excellent imaging outcome in animal experiments. This is the first example of the usage of hybrid lutetium oxide nanoparticles as effective nanoprobes. Furthermore, biodistribution, clearance route, as well as long-term toxicity are investigated in detail after intravenous injection in a murine model, indicating the overall safety of PEG-UCNPs. Compared with previous lanthanide fluorides, our nanoprobes exhibit more advantages, such as facile construction process and nearly total excretion from the animal body within a month. Taken together, these results promise the use of PEG-UCNPs as a safe and efficient nanoparticulate contrast agent for potential application in multimodal imaging. PMID:24610806

  3. Effects of iron-tetrasulfophthalocyanine on the catalytic activities of Pt\\/C, PtRu\\/C, and Pd\\/C catalysts in a multi-anode direct formic acid fuel cell

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2010-01-01

    This paper reports a systematic study of the effects of a promoter, iron-tetrasulfophthalocyanine (FeTSPc), on the catalytic\\u000a activities of carbon supported Pt, PtRu, and Pd catalysts (Pt\\/C, PtRu\\/C, and Pd\\/C) for formic acid oxidation. A multi-anode\\u000a direct formic acid fuel cell (DFAFC) was used to compare the effects on each catalyst of adding FeTSPc to the fuel stream.\\u000a The FeTSPc

  4. The Production and Export of Bioavailable Iron from Ice Sheets - the Importance of Colloidal and Nanoparticulate Phases

    NASA Astrophysics Data System (ADS)

    Hawkings, J.; Wadham, J. L.; Tranter, M.; Raiswell, R.; Benning, L. G.; Statham, P. J.; Tedstone, A.; Nienow, P. W.; Telling, J.; Bagshaw, E.

    2013-12-01

    Glaciers cover approximately 10% of the world's land surface at present, but our knowledge of biogeochemical processes occurring beneath them is still limited, as is our understanding of their impact on downstream ecosystems via the export of nutrients in runoff. Recent work has suggested that glaciers are a primary source of nutrients to near coastal areas(1). For example, macronutrients, such as nitrogen and phosphorus, and micronutrients, such as iron, may support primary production(2,3). Nutrient limitation of primary producers is known to be prevalent in large sectors of the world's oceans and iron is a significant limiting nutrient in Polar waters(4,5). Significantly, large oceanic algal blooms have been observed in polar areas where glacial influence is large(6,7). Our knowledge of iron speciation, concentrations and export dynamics in glacial meltwater is limited due, in part, to problems associated with collecting trace measurements in remote field locations. For example, recent work has indicated large uncertainty in 'dissolved' meltwater iron concentrations (0.2 - 4000 ?M(8,9)). There is currently a dearth of information about labile nanoparticulate iron in glacial meltwaters, as well as export dynamics from large ice sheet catchments. Existing research has focused on small catchment examples(8,10), which behave differently to larger catchments(11). Presented here is the first time series of daily variations in meltwater iron concentrations (dissolved, filterable colloidal/nanoparticulate and bioavailable suspended sediment bound) from two large contrasting glacial catchments in Greenland over the 2012 and 2013 summer melt seasons. We also present the first estimates of iron concentrations in Greenlandic icebergs, which have been identified as hot spots of biological activity in the open ocean(12,13). Budgets for ice sheets based on our data demonstrate the importance of glaciers in global nutrient cycles, and reveal a large and previously under-appreciated component of the global iron cycle. References 1 Hood, E. & Scott, D, Nat Geosci 1, 583-587 (2008) 2 Wadham, J. et al., Earth Env Sci T R So (2013) 3 Gerringa, L. J. A. et al., Deep-Sea Res Pt II 71-76, 16-31 (2012) 4 Martin, J. H. & Fitzwater, S. E., Nature 331, 341-343 (1988) 5 Martin, J. H., Fitzwater, S. E. & Gordon, R. M., Global Biogeochem Cy 4, 5-12 (1990) 6 Perrette, M., Yool, A., Quartly, G. D. & Popova, E. E., Biogeosciences 8, 515-524 (2011) 7 Frajka-Williams, E. & Rhines, P. B., Deep-Sea Res Pt I 57, 541-552 (2010) 8 Statham, P. J., Skidmore, M. & Tranter, M., Global Biogeochem Cy 22 (2008) 9 Mikucki, J. A. et al., Science 324, 397-400 (2009) 10 Bhatia, M. P. et al., Nat Geosci (2013) 11 Wadham, J. L. et al., Global Biogeochem Cy 24 (2010) 12 Smith, K. L. et al., Science 317, 478-482 (2007) 13 Raiswell, R. & Canfield, D. E., Geochemical Perspectives 1, 1-220 (2012)

  5. Nanoparticulate TiO2 protection of midgut damage in the silkworm (Bombyx mori) following phoxim exposure.

    PubMed

    Wang, Ling; Su, Mingyu; Zhao, Xiaoyang; Hong, Jie; Yu, Xiaohong; Xu, Bingqing; Sheng, Lei; Liu, Dong; Shen, Weide; Li, Bing; Hong, Fashui

    2015-04-01

    Bombyx mori (B. mori) is often subjected to phoxim poisoning in China due to phoxim exposure, which leads to a decrease in silk production. Nanoparticulate (NP) titanium dioxide (nano-TiO2) has been shown to attenuate damages in B. mori caused by phoxim exposure. However, little is known about the molecular mechanisms of midgut injury due to organophosphorus insecticide exposure and its repair by nano-TiO2 pretreatment. In this study, phoxim exposure for 36 h led to significant decreases in body weight and survival and increased oxidative stress and midgut injury. Pretreatment with nano-TiO2 attenuated the phoxim-induced midgut injury, increased body weight and survival, and decreased oxidative stress in the midgut of B. mori. Digital gene-expression data showed that exposure to phoxim results in significant changes in the expression of 254 genes in the phoxim-exposed midgut and 303 genes in phoxim + nano-TiO2-exposed midgut. Specifically, phoxim exposure led to upregulation of Tpx, ?-amylase, trypsin, and glycoside hydrolase genes involved in digestion and absorption. Phoxim exposure also led to the downregulation of Cyp450 and Cyp4C1 genes involved in an antioxidant capacity. In contrast, a combination of both phoxim and nano-TiO2 treatment significantly decreased the change in ?-amylase, trypsin, and glycoside hydrolases (GHs), which are involved in digestion and absorption. These results indicated that Tpx, ?-amylase, trypsin, GHs, Cyp450, and Cyp4C1 may be potential biomarkers of midgut toxicity caused by phoxim exposure and the attenuation of these toxic impacts by nano-TiO2. PMID:25552327

  6. Hazard and risk assessment of a nanoparticulate cerium oxide-based diesel fuel additive - a case study.

    PubMed

    Park, Barry; Donaldson, Kenneth; Duffin, Rodger; Tran, Lang; Kelly, Frank; Mudway, Ian; Morin, Jean-Paul; Guest, Robert; Jenkinson, Peter; Samaras, Zissis; Giannouli, Myrsini; Kouridis, Haris; Martin, Patricia

    2008-04-01

    Envirox is a scientifically and commercially proven diesel fuel combustion catalyst based on nanoparticulate cerium oxide and has been demonstrated to reduce fuel consumption, greenhouse gas emissions (CO(2)), and particulate emissions when added to diesel at levels of 5 mg/L. Studies have confirmed the adverse effects of particulates on respiratory and cardiac health, and while the use of Envirox contributes to a reduction in the particulate content in the air, it is necessary to demonstrate that the addition of Envirox does not alter the intrinsic toxicity of particles emitted in the exhaust. The purpose of this study was to evaluate the safety in use of Envirox by addressing the classical risk paradigm. Hazard assessment has been addressed by examining a range of in vitro cell and cell-free endpoints to assess the toxicity of cerium oxide nanoparticles as well as particulates emitted from engines using Envirox. Exposure assessment has taken data from modeling studies and from airborne monitoring sites in London and Newcastle adjacent to routes where vehicles using Envirox passed. Data have demonstrated that for the exposure levels measured, the estimated internal dose for a referential human in a chronic exposure situation is much lower than the no-observed-effect level (NOEL) in the in vitro toxicity studies. Exposure to nano-size cerium oxide as a result of the addition of Envirox to diesel fuel at the current levels of exposure in ambient air is therefore unlikely to lead to pulmonary oxidative stress and inflammation, which are the precursors for respiratory and cardiac health problems. PMID:18444008

  7. Formulation, stability and pharmacokinetics of sugar-based salmon calcitonin-loaded nanoporous/nanoparticulate microparticles (NPMPs) for inhalation.

    PubMed

    Amaro, Maria Inês; Tewes, Frederic; Gobbo, Oliviero; Tajber, Lidia; Corrigan, Owen I; Ehrhardt, Carsten; Healy, Anne Marie

    2015-04-10

    A challenge exists to produce dry powder inhaler (DPI) formulations with appropriate formulation stability, biological activity and suitable physicochemical and aerosolisation characteristics that provide a viable alternative to parenteral formulations. The present study aimed to produce sugar-based nanoporous/nanoparticulate microparticles (NPMPs) loaded with a therapeutic peptide - salmon calcitonin (sCT). The physicochemical properties of the powders and their suitability for pulmonary delivery of sCT were determined. Production of powders composed of sCT loaded into raffinose or trehalose with or without hydroxypropyl-?-cyclodextrin was carried out using a laboratory scale spray dryer. Spray dried microparticles were spherical, porous and of small geometric size (?2 ?m). Aerodynamic assessment showed that the fine particle fraction (FPF) less than 5 ?m ranged from 45 to 86%, depending on the formulation. The mass median aerodynamic diameter (MMAD) varied between 1.9 and 4.7 ?m. Compared to unprocessed sCT, sCT:raffinose composite systems presented a bioactivity of approximately 100% and sCT:trehalose composite systems between 70-90% after spray drying. Storage stability studies demonstrated composite systems with raffinose to be more stable than those containing trehalose. These sugar-based salmon calcitonin-loaded NPMPs retain reasonable sCT bioactivity and have micromeritic and physicochemical properties which indicate their suitability for pulmonary delivery. Formulations presented a similar pharmacokinetic profile to sCT solution. Hence the advantage of a dry powder formulation is its non-invasive delivery route and ease of administration of the sCT. PMID:25660067

  8. Comparative Toxicity of Nanoparticulate CuO and ZnO to Soil Bacterial Communities

    PubMed Central

    Rousk, Johannes; Ackermann, Kathrin; Curling, Simon F.; Jones, Davey L.

    2012-01-01

    The increasing industrial application of metal oxide Engineered Nano-Particles (ENPs) is likely to increase their environmental release to soils. While the potential of metal oxide ENPs as environmental toxicants has been shown, lack of suitable control treatments have compromised the power of many previous assessments. We evaluated the ecotoxicity of ENP (nano) forms of Zn and Cu oxides in two different soils by measuring their ability to inhibit bacterial growth. We could show a direct acute toxicity of nano-CuO acting on soil bacteria while the macroparticulate (bulk) form of CuO was not toxic. In comparison, CuSO4 was more toxic than either oxide form. Unlike Cu, all forms of Zn were toxic to soil bacteria, and the bulk-ZnO was more toxic than the nano-ZnO. The ZnSO4 addition was not consistently more toxic than the oxide forms. Consistently, we found a tight link between the dissolved concentration of metal in solution and the inhibition of bacterial growth. The inconsistent toxicological response between soils could be explained by different resulting concentrations of metals in soil solution. Our findings suggested that the principal mechanism of toxicity was dissolution of metal oxides and sulphates into a metal ion form known to be highly toxic to bacteria, and not a direct effect of nano-sized particles acting on bacteria. We propose that integrated efforts toward directly assessing bioavailable metal concentrations are more valuable than spending resources to reassess ecotoxicology of ENPs separately from general metal toxicity. PMID:22479561

  9. Photosensitization of nanoparticulate TiO2 using a Re(I)-polypyridyl complex: studies on interfacial electron transfer in the ultrafast time domain.

    PubMed

    Kar, Prasenjit; Banerjee, Tanmay; Verma, Sandeep; Sen, Anik; Das, Amitava; Ganguly, Bishwajit; Ghosh, Hirendra N

    2012-06-14

    We have synthesized a new photoactive rhenium(i)-complex having a pendant catechol functionality [Re(CO)(3)Cl(L)] (1) (L is 4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol) for studying the dynamics of the interfacial electron transfer between nanoparticulate TiO(2) and the photoexcited states of this Re(i)-complex using femtosecond transient absorption spectroscopy. Our steady state absorption studies revealed that complex 1 can bind strongly to TiO(2) surfaces through the catechol functionality with the formation of a charge transfer (CT) complex, which has been confirmed by the appearance of a new red-shifted CT band. The longer wavelength absorption band for 1, bound to TiO(2) through the proposed catecholate functionality, could also be explained based on the DFT calculations. Dynamics of the interfacial electron transfer between 1 and TiO(2) nanoparticles was investigated by studying kinetics at various wavelengths in the visible and near infrared regions. Electron injection into the conduction band of the nanoparticulate TiO(2) was confirmed by detection of the conduction band electron in TiO(2) ([e(-)](TiO(2)(CB))) and the cation radical of the adsorbed dye (1?(+)) in real time as monitored by transient absorption spectroscopy. A single exponential and pulse-width limited (<100 fs) electron injection was observed. Back electron transfer dynamics was determined by monitoring the decay kinetics of 1?(+) and . PMID:22549294

  10. Synthese de nanoparticules plasmoniques par laser femtoseconde en milieu liquide pour des applications biomedicales

    NASA Astrophysics Data System (ADS)

    Besner, Sebastien

    The femtosecond laser synthesis of plasmonic nanoparticles (Au, Ag, Cu, AuAg, AuCu) is described. The approach relies on the fs laser ablation of a target immersed in a liquid, followed by the laser-induced fragmentation and growth of nanoparticles in solution. This two-step methodology significantly enhances the production rate, the reproducibility and the size control of nanoparticles in comparison to the direct laser ablation based technique. For gold, the laser-induced growth of nanometric seeds initially formed by laser ablation in the presence of a stabilizing agent allows the synthesis of functionalized nanoparticles with sizes ranging from 3-76 nm and coefficients of variation (COV) varying between 15-30%. In comparison to the direct laser ablation, the size control is much simpler, as it uniquely depends on the gold to stabilizing agent molecular concentration ratio. The approach has been described for dextran and polyethylene glycol (PEG), but can be extended to all stabilizing agents and open new avenues in the formation of various novel bioconjugates. The fs laser ablation and fragmentation also allow the synthesis of stable and low dispersed Au nanoparticles in pure water. These nanoparticles are unique for sensing applications with high sensitivity based on surface enhanced Raman scattering (SERS), since they greatly reduce the noise associated with surface contaminants and byproducts found in solution. The formation of various nanospheres with predetermined size, shape and composition (AuxAg(1-x), AuxCu(1-x) ) is also reported by the use of a fs irradiation of a mixture of two pure metallic ix colloidal solutions in a very simple chemical environment, e.g. water and a stabilizing agent. From a chemical point of view, oxidation of silver nanoparticles is significantly reduced by the incorporation of a small amount of gold and is completely inhibited for a gold atomic fraction larger than 0.4-0.5. The bifunctional nature related to the partial oxidation of the gold nanoparticle surface allows a wide range of stabilization mechanisms. The stabilization by hydrophobic-hydrophobic interaction, by hydrogen bonds formation, by chemisorptions of thiols and by electrostatic interactions is evaluated. A new class of stabilizing agents, biopolymers, is also introduced. The addition of these polymers during the laser ablation, fragmentation or growth process enables in situ surface functionalization and efficient size control. The biocompatibility of these stabilizers also allows the direct introduction of nanoparticles in in vitro or in vivo applications without further purification. Significant efforts have also been undertaken to check the possible degradation of the polymers used during the laser process. These studies demonstrate a low degradation via an oxidation mechanism, involving the production of free radicals and oxidizing species by dissociation of water molecules during the laser process. Finally, the mechanisms of laser ablation in liquids and a growth model for the nanoparticles are proposed based on experimental results from literature and this thesis. The formation of nanoparticles is described by three distinct phases. First, a fast nucleation and condensation of the ejected species occur in the plasma and are caused by extremely high cooling rates, which lead to a strong supersaturation. This short nucleation and condensation phase is followed by a marked growth of the liquid (and still hot) nuclei by coalescence. After solidification, these nuclei should have sizes below 2 nm and be mostly condensed at the liquid-vapor interface of the growing cavitation bubble. Without the presence of stabilizing agent, growth by atomic diffusion and coalescence continue inside the cavitation bubble and should be accelerated following its collapse. Nanoparticles and unreacted monomers are then propelled out of the ablation zone by the secondary shock wave associated with the collapse of the cavitation bubble and further grow in solution. This cycle is repeated for each laser pulse and interaction between species

  11. Mecanismes de deformation de nanoparticules d'Au par irradiation ionique

    NASA Astrophysics Data System (ADS)

    Harkati Kerbouah, Chahineze

    2011-12-01

    In the present thesis, we study the anisotropic deformation of gold nanoparticles embedded in amorphous silica or crystalline aluminum arsenide, under ion bombardment. We try to comprehend the mechanism responsible for this deformation and to remove any ambiguity related to the explanation of this phenomenon. A hybrid process combining sputtering and plasma enhanced chemical vapour deposition was used to fabricate Au/SiO2 layers on fused silica substrates. Structures with single and multilayer were obtained. Heating during or after deposition activates the Au atom agglomeration and favours the growth of the nanoparticles. Also, a Au/AlAs nanocomposite was obtained by ion implantation of AlAs films, followed by rapid thermal annealing. The samples of the two nanocomposites, cooled with liquid nitrogen, were irradiated with 2 to 40 MeV Cu, Si, Au or In ion beams, at fluences ranging from 1x10 13 to 4x1015 ions/cm2, using a Tandem or Tandetron accelerator. The structural and morphological properties of the Au/SiO2 nanocomposite were extracted by optical means; the frequency and the width of surface plasmon resonance band depend on the nanoparticle shape and size, their concentration, the inter-particle distance and the dielectric properties of material in which the particles are embedded. The aluminum arsenide crystallinity was studied by two techniques: Raman spectroscopy and Rutherford backscattering spectrometry in channelling configuration (RBS/ channelling). The Au concentration in the nanocomposite layers was deducted from RBS results. The size distribution and metallic nanoparticles shape transformation in both nanocomposites were observed by electronic transmission microscopy. The results obtained within the framework of this work are the subject of three journal papers. The first publication shows the possibility of manipulating the width and spectral position of the gold nanoparticle absorption band in Au/SiO2 nanocomposites by modifying their structure (form, size and inter-particle distance). The obtained Au nanoparticles are nearly spherical. The surface plasmon (PS) absorption band corresponding to the distant particles is located at 520 nm. After ion irradiation, the spherical nanoparticles transform into ellipsoids aligned along the ion beam. The absorption band splits into two bands: transversal and longitudinal. The band corresponding to the ellipsoids small axis (transversal) is blue-shifted and that corresponding to the long axis (longitudinal) is red-shifted indicating the elongation of particles in the beam direction. The second paper is consecrated to the crucial role of the plastic deformation of the matrix and to the importance of the metal atomic mobility in the anisotropic nanoparticles deformation in Au/SiO 2 nanocomposites. Our measurements show that a threshold value of 2 keV/nm (electronic stopping power) is necessary for the deformation of Au nanoparticles. This value is close to that required for silica deformation. Mobility of the Au atoms at the time of the ion passage is confirmed by temperature calculation within the ionic track. The third paper treats the attempt of formation and deformation of Au nanoparticles in crystalline aluminum arsenide matrix known by its high resistance to amorphisation and deformation under ionic bombardment. The principal result of the last article confirms the essential role of the matrix. It proves that the anisotropic deformation of surrounding material is indispensable for gold nanoparticles deformation. The experimental results mentioned above and temperature calculations within ionic tracks allowed us to propose the following anisotropic deformation scenario of Au nanoparticles embedded in Au/SiO2 nanocomposite: (1) Each ion crossing the silica melts (very briefly) a narrow cylinder around its trajectory forming thus a latent track. This is consistent with the observed threshold value in the electronic stopping power. (2) The cumulative effect of many separate ion impacts leads to the anisotropic growth of the silica matrix which contracts in the direct

  12. Control Banding Nanotool: Evaluation of a qualitative risk assessment method for the control of nanoparticulate exposures

    SciTech Connect

    Zalk, D; Paik, S; Swuste, P

    2009-01-27

    Control Banding strategies offer a simplified control of worker exposures when there is an absence of firm toxicological and exposure information. The nanotechnology industry fits this classification as there are overwhelming uncertainties of work-related health risks posed by nanomaterials. Many experts have suggested Control Banding as a solution for these issues. A recent survey shows a majority of nanomaterial users are not performing a basic risk assessment of their product in use. A Control Banding Nanotool has been developed and implemented to afford a qualitative risk assessment toward the control of nanoparticle exposures. The international use of the Control Banding Nanotool reflects on both its need and its possibilities. By developing this dynamic Control Banding Nanotool within the realm of the scientific information available, this application of Control Banding appears to be a useful approach for assessing the risk of nanomaterial operations. This success can be seen in providing recommendations for appropriate engineering controls, facilitating the allocation of resources to the activities that most need them, and initiating an appropriate discussion of these risks with nonexperts. Experts have requested standardization of toxicological parameters, affording better utility and consistency of research. This database of toxicological research findings should be harnessed and presented in a format feeding directly into the Control Banding Nanotool severity and probability risk matrix. Making the latest research available for experts and practitioners alike will provide the best protection of workers in the nanotechnology industries. This presentation will also show the science behind the simplified Control Banding Nanotool approach, its structure, weighting of risks, utility for exposure mitigation, and the research needs to bolster its effectiveness.

  13. On-line FTIR spectroscopic investigations of methanol oxidation in a direct methanol fuel cell

    SciTech Connect

    Lin, W.F.; Wang, J.T.; Savinell, R.F. [Case Western Reserve Univ., Cleveland, OH (United States)

    1997-06-01

    A real-time Fourier transform infrared spectroscopy (FTIRS) analysis of the products of methanol oxidation in a prototype direct-methanol fuel cell operating at high temperatures (150 to 185 C) is reported here. The methanol oxidation products on platinum black and platinum-ruthenium catalyst surfaces were determined as a function of the fuel cell operating temperature, current density, and methanol/water mole ratio. Neither formaldehyde nor formic acid was detected in anode exhaust gas at all cell operating conditions. The product distributions of methanol oxidation obtained by on-line FTIRS are consistent with previous results obtained by on-line mass spectroscopy under similar conditions. With pure methanol in anode feed, methanaldimethylacetal was found to be the main product, methyl formate and CO{sub 2} were also found. However, when water was present in the anode feed, the main product was CO{sub 2}, and the formation of methanal-dimethylacetal and methyl formate decreased significantly with increase of the water/methanol mole ratio. Increase of cell operating temperature enhanced the formation of CO{sub 2} and decreased the formation of methanaldimethylacetal and methyl formate. Pt/Ru catalyst is more active for methanol oxidation and has a higher selectivity toward CO{sub 2} formation than Pt-black. Nearly complete methanol oxidation, i.e., the product was almost exclusively CO{sub 2}, was achieved using a Pt/Ru catalyst and a water/methanol mole ratio of 2 or higher in the anode feed at a temperature of 185 C or above.

  14. Combustion Synthesis of Nanoparticulate LiMgxMn1-xPO4 (x=0, 0.1, 0.2) Carbon Composites

    SciTech Connect

    Doeff, Marca M; Chen, Jiajun; Conry, Thomas E.; Wang, Ruigang; Wilcox, James; Aumentado, Albert

    2009-12-14

    A combustion synthesis technique was used to prepare nanoparticulate LiMgxMn1-xPO4 (x=0, 0.1,0.2)/carbon composites. Powders consisted of carbon-coated particles about 30 nm in diameter, which were partly agglomerated into larger secondary particles. The utilization of the active materials in lithium cells depended most strongly upon the post-treatment and the Mg content, and was not influenced by the amount of carbon. Best results were achieved with a hydrothermally treated LiMg0.2Mn0.8PO4/C composite, which exhibited close to 50percent utilization of the theoretical capacity at a C/2 discharge rate.

  15. Hybrid polymeric hydrogels for ocular drug delivery: nanoparticulate systems from copolymers of acrylic acid-functionalized chitosan and N-isopropylacrylamide or 2-hydroxyethyl methacrylate

    NASA Astrophysics Data System (ADS)

    Barbu, Eugen; Verestiuc, Liliana; Iancu, Mihaela; Jatariu, Anca; Lungu, Adriana; Tsibouklis, John

    2009-06-01

    Nanoparticulate hybrid polymeric hydrogels (10-70 nm) have been obtained via the radical-induced co-polymerization of acrylic acid-functionalized chitosan with either N-isopropylacrylamide or 2-hydroxyethyl methacrylate, and the materials have been investigated for their ability to act as controlled release vehicles in ophthalmic drug delivery. Studies on the effects of network structure upon swelling properties, adhesiveness to substrates that mimic mucosal surfaces and biodegradability, coupled with in vitro drug release investigations employing ophthalmic drugs with differing aqueous solubilities, have identified nanoparticle compositions for each of the candidate drug molecules. The hybrid nanoparticles combine the temperature sensitivity of N-isopropylacrylamide or the good swelling characteristics of 2-hydroxyethyl methacrylate with the susceptibility of chitosan to lysozyme-induced biodegradation.

  16. SiO2 Nanoparticule-induced size-dependent genotoxicity - an in vitro study using sister chromatid exchange, micronucleus and comet assay.

    PubMed

    Battal, Dilek; Çelik, Ayla; Güler, Gizem; Akta?, Ayça; Yildirimcan, Saadet; Ocakoglu, Kasim; Çömeleko?lu, Ülkü

    2015-04-01

    Fine particles with a characteristic size smaller than 100?nm (i.e. nanoparticlesspread out in nowadays life. Silicon or Si, is one of the most abundant chemical elements found on the Earth. Its oxide forms, such as silicate (SiO4) and silicon dioxide, also known as silica (SiO2), are the main constituents of sand and quartz contributing to 90% of the Earth's crust. In this work, three genotoxicity systems "sister chromatid exchange, cytokinesis block micronucleus test and single cell gel electrophoresis (comet) assay" were employed to provide further insight into the cytotoxic and mutagenic/genotoxic potential of SiO2 nanoparticules (particle size 6?nm, 20?nm, 50?nm) in cultured peripheral blood lymphocytes as in vitro. It was observed that there is a significant decrease in Mitotic index (MI), Cytokinesis block proliferation index (CBPI), proliferation index (PRI) values expressed as Cell Kinetic parameters compared with negative control (p?nanoparticules is dependent to particule size. PMID:24960636

  17. Direct writing of metal nanostructures: lithographic tools for nanoplasmonics research.

    PubMed

    Leggett, Graham J

    2011-03-22

    Continued progress in the fast-growing field of nanoplasmonics will require the development of new methods for the fabrication of metal nanostructures. Optical lithography provides a continually expanding tool box. Two-photon processes, as demonstrated by Shukla et al. (doi: 10.1021/nn103015g), enable the fabrication of gold nanostructures encapsulated in dielectric material in a simple, direct process and offer the prospect of three-dimensional fabrication. At higher resolution, scanning probe techniques enable nanoparticle particle placement by localized oxidation, and near-field sintering of nanoparticulate films enables direct writing of nanowires. Direct laser "printing" of single gold nanoparticles offers a remarkable capability for the controlled fabrication of model structures for fundamental studies, particle-by-particle. Optical methods continue to provide a powerful support for research into metamaterials. PMID:21417494

  18. Design, characterization, and aerosolization of organic solution advanced spray-dried moxifloxacin and ofloxacin dipalmitoylphosphatidylcholine (DPPC) microparticulate/nanoparticulate powders for pulmonary inhalation aerosol delivery.

    PubMed

    Duan, Jinghua; Vogt, Frederick G; Li, Xiaojian; Hayes, Don; Mansour, Heidi M

    2013-01-01

    The aim of this study was to design and develop respirable antibiotics moxifloxacin (MOXI) hydrochloride and ofloxacin (OFLX) microparticles and nanoparticles, and multifunctional antibiotics particles with or without lung surfactant 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) for targeted dry powder inhalation delivery as a pulmonary nanomedicine. Particles were rationally designed and produced by advanced spray-drying particle engineering from an organic solution in closed mode (no water) from dilute solution. Scanning electron microscopy indicated that these particles had both optimal particle morphology and surface morphology, and the particle size distributions were suitable for pulmonary delivery. Comprehensive and systematic physicochemical characterization and in vitro aerosol dispersion performance revealed significant differences between these two fluoroquinolone antibiotics following spray drying as drug aerosols and as cospray-dried antibiotic drug: DPPC aerosols. Fourier transform infrared spectroscopy and confocal Raman microspectroscopy were employed to probe composition and interactions in the solid state. Spray-dried MOXI was rendered noncrystalline (amorphous) following organic solution advanced spray drying. This was in contrast to spray-dried OFLX, which retained partial crystallinity, as did OFLX:DPPC powders at certain compositions. Aerosol dispersion performance was conducted using inertial impaction with a dry powder inhaler device approved for human use. The present study demonstrates that the use of DPPC offers improved aerosol delivery of MOXI as cospray-dried microparticulate/nanoparticulate powders, whereas residual partial crystallinity influenced aerosol dispersion of OFLX and most of the compositions of OFLX:DPPC inhalation powders. PMID:24092972

  19. Design, Characterization, and Aerosol Dispersion Performance Modeling of Advanced Spray-Dried Microparticulate/Nanoparticulate Mannitol Powders for Targeted Pulmonary Delivery as Dry Powder Inhalers

    PubMed Central

    Li, Xiaojian; Vogt, Frederick G.; Hayes, Don

    2014-01-01

    Abstract Background: The purpose was to design and characterize inhalable microparticulate/nanoparticulate dry powders of mannitol with essential particle properties for targeted dry powder delivery for cystic fibrosis mucolytic treatment by dilute organic solution spray drying, and, in addition, to tailor and correlate aerosol dispersion performance delivered as dry powder inhalers based on spray-drying conditions and solid-state physicochemical properties. Methods: Organic solution advanced spray drying from dilute solution followed by comprehensive solid-state physicochemical characterization and in vitro dry powder aerosolization were used. Results: The particle size distribution of the spray-dried (SD) powders was narrow, unimodal, and in the range of ?500?nm to 2.0??m. The particles possessed spherical particle morphology, relatively smooth surface morphology, low water content and vapor sorption (crystallization occurred at exposure above 65% relative humidity), and retention of crystallinity by polymorphic interconversion. The emitted dose, fine particle fraction (FPF), and respirable fraction (RF) were all relatively high. The mass median aerodynamic diameters were below 4??m for all SD mannitol aerosols. Conclusion: The in vitro aerosol deposition stage patterns could be tailored based on spray-drying pump rate. Positive linear correlation was observed between both FPF and RF values with spray-drying pump rates. The interplay between various spray-drying conditions, particle physicochemical properties, and aerosol dispersion performance was observed and examined, which enabled tailoring and modeling of high aerosol deposition patterns. PMID:24502451

  20. Laser welding of nanoparticulate TiO2 and transparent conducting oxide electrodes for highly efficient dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Kim, Jinsoo; Kim, Jonghyun; Lee, Myeongkyu

    2010-08-01

    Poor interfacial contact is often encountered in nanoparticulate film-based devices. The dye-sensitized solar cell (DSSC) is a representative case in which a nanoporous TiO2 electrode needs to be prepared on the transparent conducting oxide (TCO)-coated glass substrate. In this study, we demonstrate that the inter-electrode contact resistance accounts for a considerable portion of the total resistance of a DSSC and its efficiency can be greatly enhanced by welding the interface with a laser. TiO2 films formed on the TCO-coated glass substrate were irradiated with a pulsed ultraviolet laser beam at 355 nm this transmits through the TCO and glass but is strongly absorbed by TiO2. Electron microscopy analysis and impedance measurements showed that a thin continuous TiO2 layer is formed at the interface as a result of the local melting of TiO2 nanoparticles and this layer completely bridges the gap between the two electrodes, improving the current flow with a reduced contact resistance. We were able to improve the efficiency by 35-65% with this process. DSSCs fabricated using a homemade TiO2 paste revealed an efficiency improvement from ? = 3.3% to 5.4%, and an increase from 8.2% to 11.2% was achieved with the TiO2 electrodes made from a commercial paste.

  1. Organic-coated nanoparticulate zero valent iron for remediation of chemical oxygen demand (COD) and dissolved metals from tropical landfill leachate.

    PubMed

    Wijesekara, S S R M D H R; Basnayake, B F A; Vithanage, Meththika

    2014-01-01

    The use of nanoparticulate zero valent iron (NZVI) in the treatment of inorganic contaminants in landfill leachate and polluted plumes has been the subject of many studies, especially in temperate, developed countries. However, NZVI's potential for reduction of chemical oxygen demand (COD) and treatment of metal ion mixtures has not been explored in detail. We investigated the efficiency of NZVI synthesized in the presence of starch, mercaptoacetic, mercaptosuccinic, or mercaptopropenoic acid for the reduction of COD, nutrients, and metal ions from landfill leachate in tropical Sri Lanka. Synthesized NZVI were characterized with X-ray diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), thermal gravimetric analysis, Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller. Of the samples tested, Starch-NZVI (S-NZVI) and mercaptoacetic-NZVI (MA-NZVI) performed well for treatment both COD and metal mixture. The removal percentages for COD, nitrate-nitrogen, and phosphate from S-NZVI were 50, 88, and 99 %, respectively. Heavy metal removal was higher in S-NZVI (>95 %) than others. MA-NZVI, its oxidation products, and functional groups of its coating showed the maximum removal amounts for both Cu (56.27 mg g(-1)) and Zn (28.38 mg g(-1)). All mercapto-NZVI showed well-stabilized nature under FTIR and XRD investigations. Therefore, we suggest mercapto acids as better agents to enhance the air stability for NZVI since chemically bonded thiol and carbonyl groups actively participation for stabilization process. PMID:24535668

  2. A model for treating avian aspergillosis: serum and lung tissue kinetics for Japanese quail (Coturnix japonica) following single and multiple aerosol exposures of a nanoparticulate itraconazole suspension.

    PubMed

    Rundfeldt, Chris; Wyska, El?bieta; Steckel, Hartwig; Witkowski, Andrzej; Je?ewska-Witkowska, Gra?yna; Wla?, Piotr

    2013-11-01

    Aspergillosis is frequently reported in parrots, falcons and other birds held in captivity. Inhalation is the main route of infection for Aspergillus fumigatus, resulting in both acute and chronic disease conditions. Itraconazole (ITRA) is an antifungal commonly used in birds, but administration requires repeated oral dosing and the safety margin is narrow. We describe lung tissue and serum pharmacokinetics of a nanoparticulate ITRA suspension administered to Japanese quail by aerosol exposure. Aerosolized ITRA (1 and 10% suspension) administered over 30 min did not induce adverse clinical reactions in quail upon single or 5-day repeated doses. High lung concentrations, well above the inhibitory levels for A. fumigatus, of 4.14 ± 0.19 ?g/g and 27.5 ± 4.58 ?g/g (mean ± SEM, n = 3), were achieved following single-dose inhalation of 1% and 10% suspension, respectively. Upon multiple dose administration of 10% suspension, mean lung concentrations reached 104.9 ± 10.1 ?g/g. Drug clearance from the lungs was slow with terminal half-lives of 19.7 h and 35.8 h following inhalation of 1% and 10% suspension, respectively. Data suggest that lung clearance is solubility driven. Lung concentrations of hydroxy-itraconazole reached 1-2% of the ITRA lung tissue concentration indicating metabolism in lung tissue. Steady, but low, serum concentrations of ITRA could be measured after multiple dose administration, reaching less than 0.1% of the lung tissue concentration. This formulation may represent a novel, easy to administer treatment modality for fungal lung infection, preventing high systemic exposure. It may also be useful as metaphylaxis to prevent the outbreak of aspergillosis in colonized animals. PMID:23815436

  3. High-Activity PtRuPd/C Catalyst for Direct Dimethyl Ether Fuel Cells.

    PubMed

    Li, Qing; Wen, Xiaodong; Wu, Gang; Chung, Hoon T; Gao, Rui; Zelenay, Piotr

    2015-06-22

    Dimethyl ether (DME) has been considered as a promising alternative fuel for direct-feed fuel cells but lack of an efficient DME oxidation electrocatalyst has remained the challenge for the commercialization of the direct DME fuel cell. The commonly studied binary PtRu catalyst shows much lower activity in DME than methanol oxidation. In this work, guided by density functional theory (DFT) calculation, a ternary carbon-supported PtRuPd catalyst was designed and synthesized for DME electrooxidation. DFT calculations indicated that Pd in the ternary PtRuPd catalyst is capable of significantly decreasing the activation energy of the C?O and C?H bond scission during the oxidation process. As evidenced by both electrochemical measurements in an aqueous electrolyte and polymer-electrolyte fuel cell testing, the ternary catalyst shows much higher activity (two-fold enhancement at 0.5?V in fuel cells) than the state-of-the-art binary Pt50 Ru50 /C catalyst (HiSPEC 12100). PMID:25967867

  4. Synthesis and characterization of nanostructured electrocatalysts for proton exchange membrane and direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Xiong, Liufeng

    Proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC) are attractive power sources as they offer high conversion efficiencies with low or no pollution. However, the most commonly used platinum electrocatalyst is expensive and the world supply of Pt is limited. In addition, the slow oxygen reduction and methanol oxidation kinetics as well as the poisoning of the Pt catalyst at the cathode resulting from methanol permeation from the anode through the Nafion membrane to the cathode lead to significant performance loss. Also, the electrocatalyst utilization in the electrodes also needs to be improved to reduce the overall cost of the electrocatalysts and improve the fuel cell performance. This dissertation explores nanostructured Pt alloys with lower cost and higher catalytic activity than Pt for oxygen reduction in PEMFC to understand the effect of synthesis and structure on the catalytic activity, methanol tolerant Pt/TiOx nanocomposites for oxygen reduction in DMFC, nanostructured Pt-Ru alloys for methanol oxidation in DMFC, and improvement in the utilization of Pt by optimizing the membrane-electrode assembly (MEA) fabrication. From a systematic investigation of a series of Pt-M alloys (M = Fe, Co, Ni, and Cu), the catalytic activity of Pt-M alloys is correlated with the extent of atomic ordering. More ordered Pt alloys exhibit higher catalytic activity than disordered Pt alloys. The higher activity of the ordered Pt alloys is found to relate to various factors including the Pt-Pt distance, Pt: 5d orbital vacancy, {100} planar density and surface atomic configuration. The catalytic activity of the Pt alloys is also influenced by the synthesis method. Low temperature solution methods usually result in smaller particle size and higher surface area, while high temperature routes result in larger particle size and lower surface area but with a greater extent of alloying. Pt/TiOx/C nanocomposites exhibit higher performance than Pt for oxygen reduction in DMFC. The nanocomposites show higher electrchochemical surface area, lower charge transfer resistance, and higher methanol tolerance than Pt. Pt-Ru alloy synthesized by a reverse microemulsion method exhibits higher catalytic surface area than the commercial Pt-Ru. The higher catalytic activity is attributed to a better control of the particle size, crystallinity, and microstructure. Membrane-electrode assemblies (MEAs) fabricated by a modified thin film method exhibit much higher electrocatalyst utilization efficiency and performance than the conventional MEAs in PEMFC. Power densities of 715 and 610 mW/cm2 are obtained at a Pt loading of, respectively, 0.1 and 0.05 mg/cm2 and 90°C. The higher electrocatalyst utilization is attributed to the thin catalyst layer and a better continuity of the membrane/catalysts layer interface compared to that in the conventional MEAs.

  5. Mesenchymal Stem Cell Responses to Bone-Mimetic Electrospun Matrices Composed of Polycaprolactone, Collagen I and Nanoparticulate Hydroxyapatite

    PubMed Central

    Catledge, Shane A.; Xu, Yuanyuan; Hennessy, Kristin M.; Thomas, Vinoy; Jablonsky, Michael J.; Chowdhury, Shafiul; Stanishevsky, Andrei V.; Vohra, Yogesh K.; Bellis, Susan L.

    2011-01-01

    The performance of biomaterials designed for bone repair depends, in part, on the ability of the material to support the adhesion and survival of mesenchymal stem cells (MSCs). In this study, a nanofibrous bone-mimicking scaffold was electrospun from a mixture of polycaprolactone (PCL), collagen I, and hydroxyapatite (HA) nanoparticles with a dry weight ratio of 50/30/20 respectively (PCL/col/HA). The cytocompatibility of this tri-component scaffold was compared with three other scaffold formulations: 100% PCL (PCL), 100% collagen I (col), and a bi-component scaffold containing 80% PCL/20% HA (PCL/HA). Scanning electron microscopy, fluorescent live cell imaging, and MTS assays showed that MSCs adhered to the PCL, PCL/HA and PCL/col/HA scaffolds, however more rapid cell spreading and significantly greater cell proliferation was observed for MSCs on the tri-component bone-mimetic scaffolds. In contrast, the col scaffolds did not support cell spreading or survival, possibly due to the low tensile modulus of this material. PCL/col/HA scaffolds adsorbed a substantially greater quantity of the adhesive proteins, fibronectin and vitronectin, than PCL or PCL/HA following in vitro exposure to serum, or placement into rat tibiae, which may have contributed to the favorable cell responses to the tri-component substrates. In addition, cells seeded onto PCL/col/HA scaffolds showed markedly increased levels of phosphorylated FAK, a marker of integrin activation and a signaling molecule known to be important for directing cell survival and osteoblastic differentiation. Collectively these results suggest that electrospun bone-mimetic matrices serve as promising degradable substrates for bone regenerative applications. PMID:21346817

  6. Cancer Cell Gene Expression Modulated from Plasma Membrane Integrin ?v?3 by Thyroid Hormone and Nanoparticulate Tetrac

    PubMed Central

    Davis, Paul J.; Glinsky, Gennadi V.; Lin, Hung-Yun; Leith, John T.; Hercbergs, Aleck; Tang, Heng-Yuan; Ashur-Fabian, Osnat; Incerpi, Sandra; Mousa, Shaker A.

    2014-01-01

    Integrin ?v?3 is generously expressed by cancer cells and rapidly dividing endothelial cells. The principal ligands of the integrin are extracellular matrix proteins, but we have described a cell surface small molecule receptor on ?v?3 that specifically binds thyroid hormone and thyroid hormone analogs. From this receptor, thyroid hormone (l-thyroxine, T4; 3,5,3?-triiodo-l-thyronine, T3) and tetraiodothyroacetic acid (tetrac) regulate expression of specific genes by a mechanism that is initiated non-genomically. At the integrin, T4 and T3 at physiological concentrations are pro-angiogenic by multiple mechanisms that include gene expression, and T4 supports tumor cell proliferation. Tetrac blocks the transcriptional activities directed by T4 and T3 at ?v?3, but, independently of T4 and T3, tetrac modulates transcription of cancer cell genes that are important to cell survival pathways, control of the cell cycle, angiogenesis, apoptosis, cell export of chemotherapeutic agents, and repair of double-strand DNA breaks. We have covalently bound tetrac to a 200?nm biodegradable nanoparticle that prohibits cell entry of tetrac and limits its action to the hormone receptor on the extracellular domain of plasma membrane ?v?3. This reformulation has greater potency than unmodified tetrac at the integrin and affects a broader range of cancer-relevant genes. In addition to these actions on intra-cellular kinase-mediated regulation of gene expression, hormone analogs at ?v?3 have additional effects on intra-cellular protein-trafficking (cytosol compartment to nucleus), nucleoprotein phosphorylation, and generation of nuclear coactivator complexes that are relevant to traditional genomic actions of T3. Thus, previously unrecognized cell surface-initiated actions of thyroid hormone and tetrac formulations at ?v?3 offer opportunities to regulate angiogenesis and multiple aspects of cancer cell behavior. PMID:25628605

  7. Large-scale Manufacturing of Nanoparticulate-based Lubrication Additives for Improved Energy Efficiency and Reduced Emissions

    SciTech Connect

    Erdemir, Ali [Argonne National Laboratory] [Argonne National Laboratory

    2013-09-26

    This project was funded under the Department of Energy (DOE) Lab Call on Nanomanufacturing for Energy Efficiency and was directed toward the development of novel boron-based nanocolloidal lubrication additives for improving the friction and wear performance of machine components in a wide range of industrial and transportation applications. Argonne?s research team concentrated on the scientific and technical aspects of the project, using a range of state-of-the art analytical and tribological test facilities. Argonne has extensive past experience and expertise in working with boron-based solid and liquid lubrication additives, and has intellectual property ownership of several. There were two industrial collaborators in this project: Ashland Oil (represented by its Valvoline subsidiary) and Primet Precision Materials, Inc. (a leading nanomaterials company). There was also a sub-contract with the University of Arkansas. The major objectives of the project were to develop novel boron-based nanocolloidal lubrication additives and to optimize and verify their performance under boundary-lubricated sliding conditions. The project also tackled problems related to colloidal dispersion, larger-scale manufacturing and blending of nano-additives with base carrier oils. Other important issues dealt with in the project were determination of the optimum size and concentration of the particles and compatibility with various base fluids and/or additives. Boron-based particulate additives considered in this project included boric acid (H{sub 3}BO{sub 3}), hexagonal boron nitride (h-BN), boron oxide, and borax. As part of this project, we also explored a hybrid MoS{sub 2} + boric acid formulation approach for more effective lubrication and reported the results. The major motivation behind this work was to reduce energy losses related to friction and wear in a wide spectrum of mechanical systems and thereby reduce our dependence on imported oil. Growing concern over greenhouse gas emissions was also a major reason. The transportation sector alone consumes about 13 million barrels of crude oil per day (nearly 60% of which is imported) and is responsible for about 30% of the CO{sub 2} emission. When we consider manufacturing and other energy-intensive industrial processes, the amount of petroleum being consumed due to friction and wear reaches more than 20 million barrels per day (from official energy statistics, U.S. Energy Information Administration). Frequent remanufacturing and/or replacement of worn parts due to friction-, wear-, and scuffing-related degradations also consume significant amounts of energy and give rise to additional CO{sub 2} emission. Overall, the total annual cost of friction- and wear-related energy and material losses is estimated to be rather significant (i.e., as much as 5% of the gross national products of highly industrialized nations). It is projected that more than half of the total friction- and wear-related energy losses can be recovered by developing and implementing advanced friction and wear control technologies. In transportation vehicles alone, 10% to 15% of the fuel energy is spent to overcome friction. If we can cut down the friction- and wear-related energy losses by half, then we can potentially save up to 1.5 million barrels of petroleum per day. Also, less friction and wear would mean less energy consumption as well as less carbon emissions and hazardous byproducts being generated and released to the environment. New and more robust anti-friction and -wear control technologies may thus have a significant positive impact on improving the efficiency and environmental cleanliness of the current legacy fleet and future transportation systems. Effective control of friction in other industrial sectors such as manufacturing, power generation, mining and oil exploration, and agricultural and earthmoving machinery may bring more energy savings. Therefore, this project was timely and responsive to the energy and environmental objectives of DOE and our nation. In this project, most of the boron-based mater

  8. Aggregate breakdown of nanoparticulate titania

    NASA Astrophysics Data System (ADS)

    Venugopal, Navin

    Six nanosized titanium dioxide powders synthesized from a sulfate process were investigated. The targeted end-use of this powder was for a de-NOx catalyst honeycomb monolith. Alteration of synthesis parameters had resulted principally in differences in soluble ion level and specific surface area of the powders. The goal of this investigation was to understand the role of synthesis parameters in the aggregation behavior of these powders. Investigation via scanning electron microscopy of the powders revealed three different aggregation iterations at specific length scales. Secondary and higher order aggregate strength was investigated via oscillatory stress rheometry as a means of simulating shear conditions encountered during extrusion. G' and G'' were measured as a function of the applied oscillatory stress. Oscillatory rheometry indicated a strong variation as a function of the sulfate level of the particles in the viscoelastic yield strengths. Powder yield stresses ranged from 3.0 Pa to 24.0 Pa of oscillatory stress. Compaction curves to 750 MPa found strong similarities in extrapolated yield point of stage I and II compaction for each of the powders (at approximately 500 MPa) suggesting that the variation in sulfate was greatest above the primary aggregate level. Scanning electron microscopy of samples at different states of shear in oscillatory rheometry confirmed the variation in the linear elastic region and the viscous flow regime. A technique of this investigation was to approach aggregation via a novel perspective: aggregates are distinguished as being loose open structures that are highly disordered and stochastic in nature. The methodology used was to investigate the shear stresses required to rupture the various aggregation stages encountered and investigate the attempt to realign the now free-flowing constituents comprising the aggregate into a denser configuration. Mercury porosimetry was utilized to measure the pore size of the compact resulting from compaction via dry pressing and tape casting secondary scale aggregates. Mercury porosimetry of tapes cast at 0.85 and 9.09 cm/sec exhibited pore sizes ranging from 200-500 nm suggesting packing of intact micron-sized primary aggregates. Porosimetry further showed that this peak was absent in pressed pellets corroborating arguments of ruptured primary aggregates during compaction to 750 MPa.

  9. Direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Rice, C.; Ha, S.; Masel, R. I.; Waszczuk, P.; Wieckowski, A.; Barnard, Tom

    The performance of formic acid fuel oxidation on a solid PEM fuel cell at 60 °C is reported. We find that formic acid is an excellent fuel for a fuel cell. A model cell, using a proprietary anode catalyst produced currents up to 134 mA/cm 2 and power outputs up to 48.8 mW/cm 2. Open circuit potentials (OCPs) are about 0.72 V. The fuel cell runs successfully over formic acid concentrations between 5 and 20 M with little crossover or degradation in performance. The anodic polarization potential of formic acid is approximately 0.1 V lower than that for methanol on a standard Pt/Ru catalyst. These results show that formic acid fuel cells are attractive alternatives for small portable fuel cell applications.

  10. Bifunctional anode catalysts for direct methanol fuel cells Jan Rossmeisl,*ab

    E-print Network

    Brankovic, Stanko R.

    catalysts tested, similar to those of a Pt­Ru bulk alloy. To validate the model, experiments on a Pt(111 alterna- tive to PEM hydrogen fuel cells that circumvents the problem of hydrogen storage.1 However and Computer Engineering, University of Houston, 4800 Calhoun Rd, Houston, TX 77204-4004, USA e Department

  11. Development of high-power electrodes for a liquid-feed direct methanol fuel cell

    E-print Network

    ®on solution and tape-casting, with unsupported Pt-Ru as an anode catalyst and carbon supported 40 wt.% Pt of non-pressurized anode side and non-humidi®ed air pressurized to 15 psi. # 2002 Elsevier Science B temperature of 100 8C at the atmospheric pressure and the other is a liquid-feed DMFC operating below 100 8C

  12. Direct Variation

    NSDL National Science Digital Library

    2012-08-29

    This learning unit from Regents Prep Exam Center introduces the topic of direct variation equations. The material includes a lesson plan, practice problems and a teacher's guide. Students will learn the basics of what a direct variation equation is and the formula for direct variation.

  13. Directives préalables

    PubMed Central

    O’Sullivan, Rory; Mailo, Kevin; Angeles, Ricardo; Agarwal, Gina

    2015-01-01

    Résumé Objectif Établir la prévalence de patients dotés de directives préalables dans une pratique familiale et décrire les points de vue des patients quant au rôle du médecin de famille dans l’amorce de discussions à propos des directives préalables. Conception Un questionnaire auquel les patients ont répondu eux-mêmes. Contexte Une clinique d’enseignement en médecine familiale achalandée en milieu urbain, à Hamilton, en Ontario. Participants Un échantillon de commodité formé de patients adultes qui se sont présentés à la clinique durant une semaine de travail typique. Principaux paramètres à l’étude La prévalence des directives préalables dans une population de patients a été déterminée et les attentes à l’endroit du rôle de leur médecin de famille ont été sollicitées. Résultats Les répondants au sondage étaient au nombre de 800 (un taux de réponse de 72,5 %) et leurs groupes d’âges étaient bien répartis; 19,7 % d’entre eux avaient rédigé des directives préalables et 43,8 % avaient déjà discuté du sujet des directives préalables, mais seulement 4,3 % de ces discussions avaient eu lieu avec un médecin de famille. Dans 5,7 % des cas, un médecin de famille avait soulevé la question; 72,3 % des répondants croyaient que les patients devraient amorcer la discussion. Les patients qui considéraient les directives préalables d’une importance extrême étaient considérablement plus enclins à vouloir que leur médecin de famille commence la conversation (rapport de cotes de 3,98; p < ,05). Conclusion Les directives préalables n’étaient pas systématiquement abordées dans la pratique familiale. La plupart des patients préféraient amorcer la discussion des directives préalables. Toutefois, les patients qui considéraient le sujet d’une extrême importance voulaient que leur médecin de famille commence la discussion.

  14. Electrodeposition of platinum-ruthenium nanoparticles on carbon nanotubes directly grown on carbon cloths for methanol oxidation

    Microsoft Academic Search

    Ming-Chi Tsai; Tsung-Kuang Yeh; Chuen-Horng Tsai

    2008-01-01

    Dense carbon nanotubes (CNTs) were grown via a thermal chemical vapor deposition (CVD) process on titanium treated carbon cloths. Platinum-ruthenium (Pt-Ru) nanoparticles were then deposited on the CNT surfaces by potentiostatic electrodeposition in mixed sulfuric acid and ethylene glycol (EG) containing aqueous electrolytes. After the deposition process, the surface morphology of prepared specimens was examined by scanning electron microscopy (SEM)

  15. Multilayered gold/silica nanoparticulate bilayer devices using layer-by-layer self organisation for flexible bending and pressure sensing applications

    SciTech Connect

    Shah Alam, Md. [Department of Electrical and Electronic Engineering, Rajshahi University of Engineering and Technology, Rajshahi 6204 (Bangladesh); Center of Excellence in Nanotechnology, Asian Institute of Technology, 12120 Pathumthani (Thailand); Mohammed, Waleed S., E-mail: waleed.m@bu.ac.th [Center of Research in Optoelectronics, Communication and Control System (BU-CROCCS), School of Engineering, Bangkok University, Pathumthani 12120 (Thailand); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Center of Excellence in Nanotechnology, Asian Institute of Technology, 12120 Pathumthani (Thailand); Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al Khoud 123 (Oman)

    2014-02-17

    A pressure and bending sensor was fabricated using multilayer thin films fabricated on a flexible substrate based on layer-by-layer self-organization of 18?nm gold nanoparticles separated by a dielectric layer of 30?nm silica nanoparticles. 50, 75, and 100 gold-silica bi-layered films were deposited and the device characteristics were studied. A threshold voltage was required for electron conduction which increases from 2.4?V for 50 bi-layers to 3.3?V for 100 bi-layers. Upon bending of the device up to about 52°, the threshold voltage and slope of the I-V curves change linearly. Electrical characterization of the multilayer films was carried out under ambient conditions with different pressures and bending angles in the direct current mode. This study demonstrates that the developed multilayer thin films can be used as pressure as well as bending sensing applications.

  16. The effect of anode flow characteristics and temperature on the performance of a direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Amphlett, John C.; Peppley, Brant A.; Halliop, Ela; Sadiq, Aamir

    An experimental direct methanol fuel cell (DMFC), designed and manufactured in-house, was used in this study. The cell is of standard filter-press configuration with parallel rectangular single-pass anode channels. The membrane electrode assembly (MEA), with a suitable Pt-Ru anode electrocatalyst, was purchased from E-TEK Inc. A 1.0 M methanol in water solution was used as the fuel and pure oxygen was used as the oxidant in all experiments. Three graphite anode plates were machined with the same flow channel configuration but each with different depth of channels. The cathode was kept the same for all experiments. Polarisation curves and ac impedance spectra were obtained for varying temperatures and channel depths. To separate the contribution of the oxygen reduction reaction to the overvoltage from the anode and membrane contributions, reference hydrogen electrode (RHE) measurements were taken. By comparing the RHE polarisation with the methanol-oxygen polarisation experiments, it was found that polarisation losses at the oxygen cathode accounted for a 40-50% of the overpotential. The variation in the performance of the cell with flow of methanol/water mix, with temperature and with current density was studied. Polarisation measurements indicate that the medium channel depth flow channels performed better than either the shallow depth or deep depth flow channels indicating that there is a complex relationship between the effect of flow velocity and the influence of the rate of production of product CO 2. AC impedance spectroscopy measurements confirmed the observed polarisation results. This method proved to be able to provide a reliable indication of the performance of the cell even when the cell had not yet achieved steady-state. In the case of the shallow channel depth anode, ac impedance revealed that it required considerably longer to achieve steady-state than the time required for the medium and deep channel depths.

  17. Light, Directly

    NSDL National Science Digital Library

    This is an activity about the concept of direct versus indirect sunlight. Learners construct and use a sun angle analyzer to investigate the effect of angle on area illuminated. The fraction of light on each square of the analyzer is then calculated and compared. A discussion at the end relates the results to the amount of sunlight falling on different parts of the Earth and the effect this has on temperature and seasons. Reprinted with permission from the Great Explorations in Math and Science (GEMS).

  18. Nanoparticulate systems for brain delivery of drugs.

    PubMed

    Kreuter, J

    2001-03-23

    The blood--brain barrier (BBB) represents an insurmountable obstacle for a large number of drugs, including antibiotics, antineoplastic agents, and a variety of central nervous system (CNS)-active drugs, especially neuropeptides. One of the possibilities to overcome this barrier is a drug delivery to the brain using nanoparticles. Drugs that have successfully been transported into the brain using this carrier include the hexapeptide dalargin, the dipeptide kytorphin, loperamide, tubocurarine, the NMDA receptor antagonist MRZ 2/576, and doxorubicin. The nanoparticles may be especially helpful for the treatment of the disseminated and very aggressive brain tumors. Intravenously injected doxorubicin-loaded polysorbate 80-coated nanoparticles were able to lead to a 40% cure in rats with intracranially transplanted glioblastomas 101/8. The mechanism of the nanoparticle-mediated transport of the drugs across the blood-brain barrier at present is not fully elucidated. The most likely mechanism is endocytosis by the endothelial cells lining the brain blood capillaries. Nanoparticle-mediated drug transport to the brain depends on the overcoating of the particles with polysorbates, especially polysorbate 80. Overcoating with these materials seems to lead to the adsorption of apolipoprotein E from blood plasma onto the nanoparticle surface. The particles then seem to mimic low density lipoprotein (LDL) particles and could interact with the LDL receptor leading to their uptake by the endothelial cells. After this the drug may be released in these cells and diffuse into the brain interior or the particles may be transcytosed. Other processes such as tight junction modulation or P-glycoprotein (Pgp) inhibition also may occur. Moreover, these mechanisms may run in parallel or may be cooperative thus enabling a drug delivery to the brain. PMID:11251246

  19. Nanoparticulate systems for brain delivery of drugs

    Microsoft Academic Search

    Jörg Kreuter

    2001-01-01

    The blood–brain barrier (BBB) represents an insurmountable obstacle for a large number of drugs, including antibiotics, antineoplastic agents, and a variety of central nervous system (CNS)-active drugs, especially neuropeptides. One of the possibilities to overcome this barrier is a drug delivery to the brain using nanoparticles. Drugs that have successfully been transported into the brain using this carrier include the

  20. Vapor Synthesis and Thermal Modification of Supportless Platinum-Ruthenium Nanotubes and Application as Methanol Electrooxidation Catalysts

    SciTech Connect

    Atkinson III, Robert [University of Tennessee (UT); Unocic, Raymond R [ORNL; Unocic, Kinga A [ORNL; Veith, Gabriel M [ORNL; Papandrew, Alexander B [ORNL; Zawodzinski, Thomas A [ORNL

    2015-01-01

    Metallic, mixed-phase, and alloyed bimetallic Pt-Ru nanotubes were synthesized by a novel route based on the sublimation of metal acetylacetonate precursors and their subsequent vapor deposition within anodic alumina templates. Nanotube architectures were tuned by thermal annealing treatments. As-synthesized nanotubes are composed of nanoparticulate, metallic platinum and hydrous ruthenium oxide whose respective thicknesses depend on the sample chemical composition. The Pt-decorated, hydrous Ru oxide nanotubes may be thermally annealed to promote a series of chemical and physical changes to the nanotube structures including alloy formation, crystallite growth and morphological evolution. Annealed Pt-Ru alloy nanotubes and their as-synthesized analogs demonstrate relatively high specific activities for the oxidation of methanol. As-synthesized, mixed-phase Pt-Ru nanotubes (0.39 mA/cm2) and metallic alloyed Pt64Ru36NTs (0.33 mA/cm2) have considerably higher area-normalized activities than PtRu black (0.22 mA/cm2) at 0.65 V vs. RHE.

  1. Complexed sol–gel synthesis of improved Pt–Ru–Os-based anode electro-catalysts for direct methanol fuel cells

    Microsoft Academic Search

    Yousef M. Alyousef; Moni Kanchan Datta; S. C. Yao; Prashant N. Kumta

    2009-01-01

    A high specific surface area (SSA) Pt–Ru–Os-based anode catalyst synthesized by a novel complexed sol–gel (CSG) process shows better catalytic activity in comparison to pure equi-atomic compositions of Pt–Ru anode catalysts synthesized by similar sol–gel processes. A homogeneous amorphous gel was successfully synthesized by complexing platinum(II) acetylacetonate, ruthenium(III) acetylacetonate and osmium(III) chloride with tetramethylammonium hydroxide (TMAH) used as a complexing

  2. Direct WIMP detection in directional experiments

    SciTech Connect

    Vergados, J. D. [Theoretical Physics Division, University of Ioannina, Ioannina, Gr 451 10 (Greece); Institute of Theoretical Physics, University of Tuebingen, Tuebingen (Germany); Faessler, Amand [Institute of Theoretical Physics, University of Tuebingen, Tuebingen (Germany)

    2007-03-01

    The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Thus the direct dark matter search, consisting of detecting the recoiling nucleus, is central to particle physics and cosmology. Modern particle theories naturally provide viable cold dark matter candidates with masses in the GeV-TeV region. Supersymmetry provides the lightest supersymmetric particle (LSP), theories in extra dimensions the lightest Kaluza-Klein particle (LKP) etc. Unfortunately, however, in nuclear recoil measurements the interesting signal cannot be easily distinguished from the background. So, to minimize the background problems, one should exploit characteristic signatures of the reaction, such as the modulation effect and, in directional experiments, the correlation of the event rates with the sun's motion. In standard nondirectional experiments the modulation is small, less than two per cent and the location of the maximum depends on the unknown particle's mass. In directional experiments, in addition to the forward-backward asymmetry due to the sun's motion, one expects a larger modulation, which depends on the direction of observation. We study such effects both in the case of a light and a heavy target. Furthermore, since it now appears that the planned experiments may be only partly directional, in the sense that they can only detect the line of the recoiling nucleus, but not the sense of direction on it, we study which of the above mentioned interesting features, if any, will persist in these less ambitious experiments.

  3. DIRECT INTERNET DATA Troubleshooting

    E-print Network

    Ashley, Michael C. B.

    DIRECT INTERNET DATA Troubleshooting Iridium Satellite LLC Rev. 2; June 15, 2001 #12;DIRECT INTERNET DATA intend to use prior to using them over Iridium (e.g., Internet browser). Cannot register with the Iridium

  4. Directional shear force microscopy

    SciTech Connect

    Burns, A. R.; Carpick, R. W.

    2001-01-15

    We describe a technique, based on shear force microscopy, that allows one to detect shear forces in a chosen direction at the nanometer scale. The lateral direction of an oscillating probe tip is determined by selecting which of the four quadrants are excited on the piezo driver. The shear forces depend directly on this lateral direction if structural anisotropies are present, as confirmed with polydiacetylene monolayers.

  5. Solar direction sensor

    Microsoft Academic Search

    K. Mori; K. Setagaya-ku

    1984-01-01

    The solar direction sensor disclosed a solar direction sensor which is mounted on an apparatus for collecting solar energy by precisely following the movement of the sun. The solar direction sensor is characterized in that it has a cylinder, an opaque flange mounted on the top end portion of the cylinder and having a diameter smaller than the inner diameter

  6. Directional fingerprint processing

    Microsoft Academic Search

    Meltem BALLAN

    1998-01-01

    We present fingerprint smoothing, classification and identification based on the singular points (delta and core points) obtained from the directional histograms of a fingerprint. Fingerprints are classified into two main categories that are called Lasso and Wirbel. The process includes directional image formation, directional image block representation, singular point detection and decision, and fingerprint classification and identification, respectively. By matching

  7. The algebra of directed complexes

    Microsoft Academic Search

    Richard Steiner

    1993-01-01

    The theory of directed complexes is a higher-dimensional generalisation of the theory of directed graphs. In a directed graph, the simple directed paths form a subset of the free category which they generate; if the graph has no directed cycles, then the simple directed paths constitute the entire category. Generalising this, in a directed complex there is a class of

  8. Direct current transformer

    NASA Technical Reports Server (NTRS)

    Khanna, S. M.; Urban, E. W. (inventors)

    1979-01-01

    A direct current transformer in which the primary consists of an elongated strip of superconductive material, across the ends of which is direct current potential is described. Parallel and closely spaced to the primary is positioned a transformer secondary consisting of a thin strip of magnetoresistive material.

  9. Direct Support Workforce Development.

    ERIC Educational Resources Information Center

    Impact, 1998

    1998-01-01

    The fourteen brief articles in this theme issue all examine challenges in the development of direct support staff working with people who have developmental disabilities. The articles also include the views of direct support providers and people with developmental disabilities themselves, as well as examples of strategies used by provider agencies…

  10. Direct Conversion of Energy.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

  11. NISTIR 7564 Directions in

    E-print Network

    NISTIR 7564 Directions in Security Metrics Research WayneJansen #12;Directions in Security Metrics Research Wayne Jansen NISTIR 7564 C O M P U T E R S E C U R I T Y Computer Security Division Information infrastructure. ITL develops tests, test methods, reference data, proof of concept implementations, and technical

  12. Direct core materials.

    PubMed

    Wilson, Paul H; Fisher, Nigel L; Bartlett, David W

    2003-09-01

    There are many materials that can be used for direct-placement cores. Although the scientific evidence is incomplete, some materials are better suited to this task than others. This article provides an overview of direct-placement core materials and highlights what clinicians should consider when assessing a new product. PMID:14558201

  13. NPOESS Direct Readout Mission

    Microsoft Academic Search

    John A. van de Wouw; John Overton; Patrick Coronado

    2004-01-01

    Preparing for the next generation polar orbiting environmental satellite system, the NPOESS system is currently undergoing the design phase of the Program. The NPOESS Direct Readout Mission will service users in the field providing regional environmental coverage with two direct broadcast links, high rate data (HRD) at 20 Mbps and low rate data (LRD) at 3.88 Mbps. Contained within these

  14. NPOESS direct readout mission

    Microsoft Academic Search

    J. W. Overton; P. Coronado; J. A. van de Wouw

    2004-01-01

    Preparing for the next generation polar orbiting environmental satellite system, the NPOESS system is currently undergoing the design phase of the program. The NPOESS direct readout mission will service users in the field providing regional environmental coverage with two direct broadcast links, the high rate data (HRD) at 20 Mbps and the low rate data link at 3.88 Mbps. Contained

  15. NPOESS Direct Readout Mission

    Microsoft Academic Search

    John A. van de Wouw; John W. Overton; Patrick Coronado

    2005-01-01

    Preparing for the next generation polar orbiting environmental satellite system, the NPOESS system is currently undergoing the design phase of the Program. The NPOESS Direct Readout Mission will service users in the field providing regional environmental coverage with two direct broadcast links, high rate data (HRD) at 20 Mbps and low rate data (LRD) at 3.88 Mbps. Contained within these

  16. AISI direct steelmaking program

    SciTech Connect

    Aukrust, E.

    1991-01-09

    AISI with co-funding from DOE has initiated a research and development program aimed at the development of a new process for direct steelmaking, and the program is discussed in this document. The project is expected to cost about $30 million over a three-year period, with the government providing approximately 77 percent of the funds and AISI the balance. In contrast to current steelmaking processes which are largely open and batch, the direct steelmaking process would be closed and continuous. Further, it would use coal directly, thereby avoiding the need for coke ovens. The second year of the Direct Steelmaking Program (November 29, 1989, through November 28, 1990) was a year of significant accomplishment. The various research programs proceeded essentially on schedule and the pilot plant, the centerpiece of the program, was completed about three months behind schedule but began operation in almost a picture-perfect manner. This report presents the last years accomplishments.

  17. Direct Dark Matter Searches

    NASA Astrophysics Data System (ADS)

    Gascon, J.

    2005-06-01

    Direct dark matter searches consist in observing in the laboratory nuclear recoils due to impact of WIMPs from our galactic halo. The status and perspectives of the leading experiments devoted to this search are discussed.

  18. The Directed Case Method

    NSDL National Science Digital Library

    Leslie Nesbitt Curtin

    2000-09-01

    Many instructors think that by incorporating case study analysis into the science classroom they will sacrifice course content. The directed case method, however, is a proven strategy for deepening and solidifying understanding of facts and concepts when

  19. BIOCHEMISTRY: Directing Biosynthesis

    NSDL National Science Digital Library

    Michael A. Fischbach (Harvard Medical School; Harvard University; Department of Biological Chemistry and Molecular Pharmacology; HHMI and the Department of Chemistry and Chemical Biology)

    2006-10-27

    Access to the article is free, however registration and sign-in are required. Genetic engineering is revealing biosynthetic pathways for the synthesis of small molecules and avenues toward cheaper syntheses. Projects aiming to direct the biosynthesis of small molecules may seek to make new compounds, make natural compounds in unnatural organisms, or alter the metabolic flux through a particular biosynthetic pathway. This Perspective presents three examples that illustrate the state of directed biosynthesis and highlight its future prospects.

  20. Directional gear ratio transmissions

    NASA Technical Reports Server (NTRS)

    Lafever, A. E. (inventor)

    1984-01-01

    Epicyclic gear transmissions which transmit output at a gear ratio dependent only upon the input's direction are considered. A transmission housing envelops two epicyclic gear assemblies, and has shafts extending from it. One shaft is attached to a sun gear within the first epicyclic gear assembly. Planet gears are held symmetrically about the sun gear by a planet gear carrier and are in mesh with both the sun gear and a ring gear. Two unidirectional clutches restrict rotation of the first planet gear carrier and ring gear to one direction. A connecting shaft drives a second sun gear at the same speed and direction as the first planet gear carrier while a connecting portion drives a second planet gear carrier at the same speed and direction as the first ring gear. The transmission's output is then transmitted by the second ring gear to the second shaft. Input is transmitted at a higher gear ratio and lower speed for all inputs in the first direction than in the opposite direction.

  1. Electrohydrodynamic direct-writing

    NASA Astrophysics Data System (ADS)

    Huang, Yongan; Bu, Ningbin; Duan, Yongqing; Pan, Yanqiao; Liu, Huimin; Yin, Zhouping; Xiong, Youlun

    2013-11-01

    The electrohydrodynamic (EHD) direct-writing technique can be used to print solid/liquid straight/serpentine nanofibers onto a large-area substrate, in a direct, continuous, and controllable manner. It is a high-efficiency and cost-effective solution-processable technique to satisfy increasing demands of large-area micro/nano-manufacturing. It is ground-breaking to direct-write sub-100 nm fibers on a rigid/flexible substrate using organic materials. A comprehensive review is presented on the research and developments related to the EHD direct-writing technique and print heads. Many developments have been presented to improve the controllability of the electrospun fibers to form high-resolution patterns and devices. EHD direct-writing is characterized by its non-contact, additive and reproducible processing, high resolution, and compatibility with organic materials. It combines dip-pen, inkjet, and electrospinning by providing the feasibility of controllable electrospinning for sub-100 nm nanofabrication, and overcomes the drawbacks of conventional electron-beam lithography, which is relatively slow, complicated and expensive.

  2. Direct conversion technology

    NASA Technical Reports Server (NTRS)

    Massier, Paul F.; Bankston, C. P.; Williams, R.; Underwood, M.; Jeffries-Nakamura, B.; Fabris, G.

    1989-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal Magnetohydrodynamic Electrical Generator (LMMHD) for the period January 1, 1989 through December 31, 1989. Research on these concepts was initiated during October 1987. Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (nitinol heat engines); and also, more complete discussions of AMTEC and LMMHD systems.

  3. Direct conversion technology

    SciTech Connect

    Massier, P.F.; Back, L.H.; Ryan, M.A.; Fabris, G.

    1992-01-07

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1, 1991 through December 31, 1991. Research on AMTEC and on LMMHD was initiated during October 1987. Reports prepared on previous occasions (Refs. 1--5) contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  4. Direct conversion technology

    NASA Astrophysics Data System (ADS)

    Massier, P. F.; Back, L. H.; Ryan, M. A.; Fabris, G.

    1992-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period 1 Jan. 1991 - 31 Dec. 1991. Research on AMTEC and on LMMHD was initiated during Oct. 1987. Reports prepared on previous occasions contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  5. Directional spherical multipole wavelets

    SciTech Connect

    Hayn, Michael; Holschneider, Matthias [Institute for Mathematics, University Potsdam, Am Neuen Palais 10, 144 69 Potsdam (Germany)

    2009-07-15

    We construct a family of admissible analysis reconstruction pairs of wavelet families on the sphere. The construction is an extension of the isotropic Poisson wavelets. Similar to those, the directional wavelets allow a finite expansion in terms of off-center multipoles. Unlike the isotropic case, the directional wavelets are not a tight frame. However, at small scales, they almost behave like a tight frame. We give an explicit formula for the pseudodifferential operator given by the combination analysis-synthesis with respect to these wavelets. The Euclidean limit is shown to exist and an explicit formula is given. This allows us to quantify the asymptotic angular resolution of the wavelets.

  6. Direct Conversion Technology

    SciTech Connect

    Back, L.H.; Fabris, G.; Ryan, M.A.

    1992-07-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. Initially, two systems were selected for exploratory research and advanced development. These are Alkali Metal Thermal-to-Electric Converter (AMTEC) and Two-Phase Liquid Metal MD Generator (LMMHD). This report describes progress that has been made during the first six months of 1992 on research activities associated with these two systems. (GHH)

  7. Direct Conversion Technology

    NASA Astrophysics Data System (ADS)

    Back, L. H.; Fabris, G.; Ryan, M. A.

    1992-07-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. Initially, two systems were selected for exploratory research and advanced development. These systems are the Alkali Metal Thermal-to-Electric Converter (AMTEC) and the Two-Phase Liquid Metal MHD Generator (LMMHD). This report describes progress that has been made during the first six months of 1992 on research activities associated with these two systems.

  8. Directionally solidified ceramic eutectics

    NASA Technical Reports Server (NTRS)

    Ashbrook, R. L.

    1977-01-01

    The aligned structures which result from the directional solidification (DS) of ceramic eutectics are of interest because of their potential for use in electronic devices and as structural materials. Techniques for growing DS ceramic eutectics are briefly discussed. The principles and controlling parameters of DS eutectic growth are described. The criteria for plane-front growth and the effect of growth rate on interlamellar or interfiber spacing are discussed. Examples of the effect of growth parameters on the alignment of the microstructure are given. Examples of the mechanical properties of directionally solidified oxide-oxide ceramics are also cited.

  9. Conclusions and Future Directions

    ERIC Educational Resources Information Center

    Lillibridge, Fred

    2012-01-01

    Benchmarking, when done properly, offers a lot of promise for higher education units that want to improve how they do business. It is clear that much is known, but still more needs to be learned before it reaches its full potential as a useful tool. Readers of this issue of "New Directions for Institutional Research" have been treated to useful…

  10. Amalgamation for direct systems

    Microsoft Academic Search

    S. Bulman-Fleming; I. Fleischer

    1991-01-01

    Although given a somewhat more general formulation, the main body of this article deals with semilattice-indexed direct systems of a type of universal algebra for which we establish conditions that the amalgamation, the strong amalgamation and (when the algebras are ordered) an even stronger \\

  11. Direct use geothermal resources

    Microsoft Academic Search

    R. G. Bloomquist

    2002-01-01

    Direct use geothermal is usually defined to include resources in the temperature range of approximately 20°C to 150+°C (68 to 302°F). At the lower end of the range the resource generally requires the use of a heat pump for spare or process heating but some applications including aquaculture or fish farming are possible even at these low temperatures. Geothermal resources

  12. Catheter-Directed Thrombolysis

    MedlinePLUS

    ... threatening consequences. In a catheter-directed thrombolysis procedure, x-ray imaging is used to help guide a special medication ... conditions. Women should always inform their physician and x-ray ... they are pregnant. Many imaging tests are not performed during pregnancy so as ...

  13. Direct Methanol Fuel Cell

    NSDL National Science Digital Library

    This sheet provides information about direct methanol fuel cells. Details on the chemistry involved are included in graphic form along with several notes on these fuel cells. This material would be most appropriate for upper level students who already have a basic understanding of fuel cell technology and chemistry. This document may be downloaded in PDF file format.

  14. Direct from CDC's Environmental

    E-print Network

    Direct from CDC's Environmental Health Services Branch CAPT Daniel M. Harper, M and Prevention (CDC) in every issue of the Journal. EHSB's objective is to strengthen the role of state, local health for all Americans. Regarding CDC's diversity policy, Dr. Julie Louise Gerberding, director of CDC

  15. Developing Ethical Direction

    ERIC Educational Resources Information Center

    Ribble, Mike S.; Bailey,Gerald D.

    2005-01-01

    When you read or hear an unethical suggestion, such as "Steal this article and sell it to another magazine," we're guessing that your internal compass indicates "wrong direction." In other words, your internal voice says, "No, that would be wrong!" Your internal compass tells you when something is right and something is wrong. In our example, your…

  16. Audio direct broadcast satellites

    NASA Technical Reports Server (NTRS)

    Miller, J. E.

    1983-01-01

    Satellite sound broadcasting is, as the name implies, the use of satellite techniques and technology to broadcast directly from space to low-cost, consumer-quality receivers the types of sound programs commonly received in the AM and FM broadcast bands. It would be a ubiquitous service available to the general public in the home, in the car, and out in the open.

  17. Direct from CDC's Environmental

    E-print Network

    and health education. A recent World Health Organiza tion (WHO) technical report defined veterinary public health as "the sum of all contributions to the physical, mental, and social well-being of humans through Direct from CDC's Environmental Health Services Branch Hugh Mainzer, M.S, D

  18. Direct anonymous attestation

    Microsoft Academic Search

    Ernest F. Brickell; Jan Camenisch; Liqun Chen

    2004-01-01

    This paper describes the direct anonymous attestation scheme (DAA). This scheme was adopted by the Trusted Computing Group (TCG) as the method for remote authentication of a hardware module, called Trusted Platform Module (TPM), while preserving the privacy of the user of the platform that contains the module. DAA can be seen as a group signature without the feature that

  19. THE JOURNAL OF CHEMICAL PHYSICS 134, 224707 (2011) Oxygen adsorption on Pt/Ru(0001) layers

    E-print Network

    2011-01-01

    of an incoming homo- nuclear diatomic molecule. In this study, the adsorption of O2 on various epitaxially grown and annealing leads to dissociation of O2, thereby approaching the behavior for oxygen adsorption on genuine Pt monolayer islands is identified. This state is readily populated which precludes an activation barrier

  20. Core Shell Inversion during Nucleation and Growth of Bimetallic Pt/Ru Nanoparticles

    E-print Network

    Frenkel, Anatoly

    materials using this technique. Extended X-ray absorption fine structure (EXAFS) has been used to study Cd interatomic distances, coordination numbers, local disorder, and the effective valence around Mn impurity ions distributions.11 The uniform microstructural distribution obtained using this preparative

  1. DIRECT INTERNET DATA User's Guide

    E-print Network

    Ashley, Michael C. B.

    DIRECT INTERNET DATA User's Guide Iridium Satellite LLC Rev. 2; June 15, 2001 #12;DIRECT INTERNET OF CONTENTS 1 Direct Internet Data Overview ................................................................................ 32 5 Connecting to the Internet

  2. Modelling directional solidification

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.

    1987-01-01

    An improved understanding of the phenomena of importance to directional solidification is attempted to enable explanation and prediction of differences in behavior between solidification on Earth and in space. Emphasis is now on experimentally determining the influence of convection and freezing rate fluctuations on compositional homogeneity and crystalline perfection. A correlation is sought between heater temperature profiles, buoyancy-driven convection, and doping inhomogeneities using naphthalene doped with anthracene. The influence of spin-up/spin-down is determined on compositional homogeneity and microstructure of indium gallium antimonide. The effect is determined of imposed melting - freezing cycles on indium gallium antimonide. The mechanism behind the increase of grain size caused by using spin-up/spin-down in directional solidification of mercury cadimum telluride is sought.

  3. Direct insolation models

    SciTech Connect

    Bird, R.; Hulstrom, R.L.

    1980-01-01

    Several recently published models of the direct component of the broadband insolation are compared for clear sky conditions. The comparison includes seven simple models and one rigorous model that is used as a basis for determining accuracy. Where possible, the comparison is made between the results of each model for each atmospheric constituent (H/sub 2/O, CO/sub 2/, O/sub 3/, O/sub 2/, aerosol and molecular scattering) separately as well as for the combined effect of all of the constituents. Two optimum simple models of varying degrees of complexity are developed as a result of this comparison. The study indicates: aerosols dominate the attenuation of the direct beam for reasonable atmospheric conditions; molecular scattering is next in importance; water vapor is an important absorber; and carbon dioxide and oxygen are relatively unimportant as attenuators of the broadband solar energy.

  4. Direct Dark Matter Searches

    E-print Network

    N. J. Spooner

    2007-05-23

    For many working in particle physics and cosmology successful discovery and characterisation of the new particles that most likely explain the non-baryonic cold dark matter, known to comprise the majority of matter in the Universe, would be the most significant advance in physics for a century. Reviewed here is the current status of direct searches for such particles, in particular the so-called Weakly Interacting Massive Particles (WIMPs), together with a brief overview of the possible future direction of the field extrapolated from recent advances. Current best limits are at or below 10-7 pb for spin-independent neutralino coupling, sufficient that experiments are already probing SUSY models. However, new detectors with tonne-scale mass and/or capability to correlate signal events to our motion through the Galaxy will likely be needed to determine finally whether WIMPs exist.

  5. Direct hydrocarbon fuel cells

    DOEpatents

    Barnett, Scott A.; Lai, Tammy; Liu, Jiang

    2010-05-04

    The direct electrochemical oxidation of hydrocarbons in solid oxide fuel cells, to generate greater power densities at lower temperatures without carbon deposition. The performance obtained is comparable to that of fuel cells used for hydrogen, and is achieved by using novel anode composites at low operating temperatures. Such solid oxide fuel cells, regardless of fuel source or operation, can be configured advantageously using the structural geometries of this invention.

  6. Propulsion by directional adhesion

    Microsoft Academic Search

    John Bush; Manu Prakash

    2008-01-01

    The rough, hairy integument of water-walking arthropods is well known to be responsible for their water-repellency; we here consider its additional propulsive role. We demonstrate that the tilted flexible leg hairs of water-walking arthropods render the leg cuticle directionally anisotropic: contact lines advance most readily towards the leg tips. The dynamical role of the resulting unidirectional adhesion is explored, and

  7. Directional Spherical Cherenkov Detector

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Wrbanek, Susan Y.

    2010-01-01

    A proposed radiation-detecting apparatus would provide information on the kinetic energies, directions, and electric charges of highly energetic incident subatomic particles. The apparatus was originally intended for use in measuring properties of cosmic rays in outer space, but could also be adapted to terrestrial uses -- for example, radiation dosimetry aboard high-altitude aircraft and in proton radiation therapy for treatment of tumors.

  8. Direct cooling crystallization

    SciTech Connect

    Fowles, P. E.; Yan, T. S.

    1984-06-05

    A crystallization process is improved by employing direct contact cooling whereby a volatile liquid is vaporized to provide the cooling necessary to effect the crystallization. The effluent vapors of the volatile liquid may be liquified and recycled for reuse by manipulation of temperature and/or pressure. In one embodiment, durene is crystallized from a C/sub 10//sup +/ aromatics fraction using liquified n-butane as the coolant.

  9. Direct subnanosecond voltage monitors

    SciTech Connect

    Barth, J.E.; Sajeant, W.J.

    1981-01-01

    Advanced system development in the subnanosecond time frame increasingly demands high-resolution voltage measurements for both single-shot and repetitive operation. Voltage monitors having capabilities up to the hundred kilovolt level have been developed for direct measurements in discrete and transmission line geometries. Resolutions of 100 ps at 100 kV to 30 ps at 20 kV have been achieved. Detailed test data is presented and ultimate voltage scaling limits are discussed.

  10. Pneumatic Directional Control Valves

    NSDL National Science Digital Library

    Bartelt, Terry L. M.

    This learning object examines pneumatic directional control valves in two-way, three-way, and four-way valves. The presentation is interactive, as it allows the user to focus of certain valve types and cater their learning towards those. The site employs flash based animations, and also many other diagrams to address certain points. Overall, this site has nice presentation and allows presents a great deal of information.

  11. Dark Matter direct searches

    NASA Astrophysics Data System (ADS)

    Gascon, J.

    2004-03-01

    Different techniques are currently competing in the direct search of Weakly Interacting Massive Particles (WIMP) dark matter, which consists in observing in the laboratory nuclear recoils due to impact of WIMPs from our galactic halo. As an introduction to this Dark Matter session, the experimental context, the key challenges and the different techniques will be briefly summarized. The performance achieved by low-temperature detectors confers to them a leading role in this domain.

  12. Site-directed mutagenesis.

    PubMed

    Bachman, Julia

    2013-01-01

    Site-directed mutagenesis is a PCR-based method to mutate specified nucleotides of a sequence within a plasmid vector. This technique allows one to study the relative importance of a particular amino acid for protein structure and function. Typical mutations are designed to disrupt or map protein-protein interactions, mimic or block posttranslational modifications, or to silence enzymatic activity. Alternatively, noncoding changes are often used to generate rescue constructs that are resistant to knockdown via RNAi. PMID:24011050

  13. Topologies on directed graphs

    NASA Technical Reports Server (NTRS)

    Lieberman, R. N.

    1972-01-01

    Given a directed graph, a natural topology is defined and relationships between standard topological properties and graph theoretical concepts are studied. In particular, the properties of connectivity and separatedness are investigated. A metric is introduced which is shown to be related to separatedness. The topological notions of continuity and homeomorphism. A class of maps is studied which preserve both graph and topological properties. Applications involving strong maps and contractions are also presented.

  14. Direct imaging of exoplanets.

    PubMed

    Lagrange, Anne-Marie

    2014-04-28

    Most of the exoplanets known today have been discovered by indirect techniques, based on the study of the host star radial velocity or photometric temporal variations. These detections allowed the study of the planet populations in the first 5-8?AU from the central stars and have provided precious information on the way planets form and evolve at such separations. Direct imaging on 8-10?m class telescopes allows the detection of giant planets at larger separations (currently typically more than 5-10?AU) complementing the indirect techniques. So far, only a few planets have been imaged around young stars, but each of them provides an opportunity for unique dedicated studies of their orbital, physical and atmospheric properties and sometimes also on the interaction with the 'second-generation', debris discs. These few detections already challenge formation theories. In this paper, I present the results of direct imaging surveys obtained so far, and what they already tell us about giant planet (GP) formation and evolution. Individual and emblematic cases are detailed; they illustrate what future instruments will routinely deliver for a much larger number of stars. I also point out the limitations of this approach, as well as the needs for further work in terms of planet formation modelling. I finally present the progress expected in direct imaging in the near future, thanks in particular to forthcoming planet imagers on 8-10?m class telescopes. PMID:24664924

  15. Direct conversion technology

    NASA Technical Reports Server (NTRS)

    Massier, P. F.; Bankston, C. P.; Fabris, G.; Kirol, L. D.

    1988-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1988 through December 1988. Research on these concepts was initiated during October 1987. In addition, status reviews and assessments are presented for thermomagnetic converter concepts and for thermoelastic converters (Nitinol heat engines). Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic thermophotovoltaic and thermoacoustic; and also, more complete discussions of AMTEC and LMMHD systems. A tabulated summary of the various systems which have been reviewed thus far has been prepared. Some of the important technical research needs are listed and a schematic of each system is shown.

  16. Direct conversion technology

    NASA Astrophysics Data System (ADS)

    Massier, P. F.; Bankston, C. P.; Fabris, G.; Kirol, L. D.

    1988-12-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1988 through December 1988. Research on these concepts was initiated during October 1987. In addition, status reviews and assessments are presented for thermomagnetic converter concepts and for thermoelastic converters (Nitinol heat engines). Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic thermophotovoltaic and thermoacoustic; and also, more complete discussions of AMTEC and LMMHD systems. A tabulated summary of the various systems which have been reviewed thus far has been prepared. Some of the important technical research needs are listed and a schematic of each system is shown.

  17. Thick film magnetic nanoparticulate composites and method of manufacture thereof

    NASA Technical Reports Server (NTRS)

    Ma, Xinqing (Inventor); Zhang, Yide (Inventor); Ge, Shihui (Inventor); Zhang, Zongtao (Inventor); Yan, Dajing (Inventor); Xiao, Danny T. (Inventor)

    2009-01-01

    Thick film magnetic/insulating nanocomposite materials, with significantly reduced core loss, and their manufacture are described. The insulator coated magnetic nanocomposite comprises one or more magnetic components, and an insulating component. The magnetic component comprises nanometer scale particles (about 1 to about 100 nanometers) coated by a thin-layered insulating phase. While the intergrain interaction between the immediate neighboring magnetic nanoparticles separated by the insulating phase provides the desired soft magnetic properties, the insulating material provides high resistivity, which reduces eddy current loss.

  18. Application of TPGS in polymeric nanoparticulate drug delivery system

    Microsoft Academic Search

    L. Mu; P. H. Seow

    2006-01-01

    d-?-Tocopheryl polyethylene glycol 1000 succinate (TPGS) has great potential in pharmacology and nanotechnology. The present work investigated the molecular behaviour of TPGS at the air–water interface, its effect on a model bio-membrane composed of dipalmitoylphosphatidylcholine (DPPC) lipid monolayer, and the interaction between the TPGS coated nanoparticles with the lipid model membrane. Paclitaxel loaded polymeric nanoparticles with TPGS as surfactant stabiliser

  19. Magnetic Properties of Mesoporous and Nano-particulate Metal Oxides 

    E-print Network

    Hill, Adrian H

    2009-01-01

    The magnetic properties of the first row transition metal oxides are wide and varied and have been studied extensively since the 1930’s. Observations that the magnetic properties of these material types change with the ...

  20. Nanoparticulate gellants for metallized gelled liquid hydrogen with aluminum

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan; Starkovich, John; Adams, Scott

    1996-01-01

    Gelled liquid hydrogen was experimentally formulated using sol-gel technology. As a follow-on to work with cryogenic simulants, hydrogen was gelled with an alkoxide material: BTMSE. Initial results demonstrated that gellants with a specific surface area of 1000 m(exp 2)/g could be repeatably fabricated. Gelled hexane and metallized gelled hexane (with 13.8-wt% Al) were produced. Propellant settling testing was conducted for acceleration levels of 2 to 10 times normal gravity and a minimum gellant percentage was determined for stable gelled hexane and metalized gelled hexane. A cryogenic capillary rheometer was also designed, constructed, and used to determine the viscosity of gelled hydrogen. Small volumes of liquid hydrogen were gelled with a 7- to 8-wt% gellant level. The gelled H2 viscosity was 1.5 to 3.7 times that of liquid hydrogen: 0.048 to 0.116 mPa-s versus 0.03 mPa-s for liquid H2 (at 16 K and approximately 1 atm pressure).

  1. Nanoparticulate adjuvants and delivery systems for allergen immunotherapy.

    PubMed

    De Souza Rebouças, Juliana; Esparza, Irene; Ferrer, Marta; Sanz, María Luisa; Irache, Juan Manuel; Gamazo, Carlos

    2012-01-01

    In the last decades, significant progress in research and clinics has been made to offer possible innovative therapeutics for the management of allergic diseases. However, current allergen immunotherapy shows limitations concerning the long-term efficacy and safety due to local side effects and risk of anaphylaxis. Thus, effective and safe vaccines with reduced dose of allergen have been developed using adjuvants. Nevertheless, the use of adjuvants still has several disadvantages, which limits its use in human vaccines. In this context, several novel adjuvants for allergen immunotherapy are currently being investigated and developed. Currently, nanoparticles-based allergen-delivery systems have received much interest as potential adjuvants for allergen immunotherapy. It has been demonstrated that the incorporation of allergens into a delivery system plays an important role in the efficacy of allergy vaccines. Several nanoparticles-based delivery systems have been described, including biodegradable and nondegradable polymeric carriers. Therefore, this paper provides an overview of the current adjuvants used for allergen immunotherapy. Furthermore, nanoparticles-based allergen-delivery systems are focused as a novel and promising strategy for allergy vaccines. PMID:22496608

  2. Nanoparticulate Adjuvants and Delivery Systems for Allergen Immunotherapy

    PubMed Central

    De Souza Rebouças, Juliana; Esparza, Irene; Ferrer, Marta; Sanz, María Luisa; Irache, Juan Manuel; Gamazo, Carlos

    2012-01-01

    In the last decades, significant progress in research and clinics has been made to offer possible innovative therapeutics for the management of allergic diseases. However, current allergen immunotherapy shows limitations concerning the long-term efficacy and safety due to local side effects and risk of anaphylaxis. Thus, effective and safe vaccines with reduced dose of allergen have been developed using adjuvants. Nevertheless, the use of adjuvants still has several disadvantages, which limits its use in human vaccines. In this context, several novel adjuvants for allergen immunotherapy are currently being investigated and developed. Currently, nanoparticles-based allergen-delivery systems have received much interest as potential adjuvants for allergen immunotherapy. It has been demonstrated that the incorporation of allergens into a delivery system plays an important role in the efficacy of allergy vaccines. Several nanoparticles-based delivery systems have been described, including biodegradable and nondegradable polymeric carriers. Therefore, this paper provides an overview of the current adjuvants used for allergen immunotherapy. Furthermore, nanoparticles-based allergen-delivery systems are focused as a novel and promising strategy for allergy vaccines. PMID:22496608

  3. NOVEL NANOPARTICULATE CATALYSTS FOR IMPROVED VOC TREATMENT DEVICES - PHASE I

    EPA Science Inventory

    Catalytic oxidation of VOCs is increasingly used for treatment of large-volume emissions at relatively dilute VOC levels. The best performing catalytic oxidation devices for attainment of very high VOC destruction levels employ precious metal catalysts, the costs of which a...

  4. Do Spins Have Directions?

    E-print Network

    Diederik Aerts; Massimiliano Sassoli de Bianchi

    2015-01-04

    The standard Bloch sphere representation was recently generalized to the 'extended Bloch representation' describing not only systems of arbitrary dimension, but also their measurements. This model solves the measurement problem and is based on the 'hidden-measurement interpretation', according to which the Born rule results from our lack of knowledge about the interaction between measuring apparatus and the measured entity. We present here the extended Bloch model and use it to investigate the nature of quantum spin and its relation to our Euclidean space. We show that spin eigenstates cannot generally be associated with directions in the Euclidean space, but only with generalized directions in the Blochean space, which generally is a space of higher dimension. Hence, spin entities have to be considered as genuine non-spatial entities. We also show, however, that specific vectors can be identified in the Blochean theater that are isomorphic to the Euclidean space directions, and therefore representative of them, and that spin eigenstates always have a predetermined orientation with respect to them. We use the details of our results to put forward a new view of realism, that we call 'multiplex realism', providing a specific framework with which to interpret the human observations and understanding of the component parts of the world. Elements of reality can be represented in different theaters, one being our customary Euclidean space, and another one the quantum realm, revealed to us through our sophisticated experiments, whose elements of reality, in the quantum jargon, are the eigenvalues and eigenstates. Our understanding of the component parts of the world can then be guided by looking for the possible connections, in the form of partial morphisms, between the different representations, which is precisely what we do in this article with regard to spin entities.

  5. Directional Antineutrino Detection

    NASA Astrophysics Data System (ADS)

    Safdi, B. R.; Suerfu, J.

    2014-12-01

    We propose the first truly directional antineutrino detector for antineutrinos near the threshold for the inverse beta decay (IBD) of hydrogen, with potential applications including the spatial mapping of geo-neutrinos, searches for stellar antineutrinos, and the monitoring of nuclear reactors. The detector consists of adjacent and separated target and neutron-capture layers. The IBD events, which result in a neutron and a positron, take place in the target layers. These layers are thin enough so that the neutrons escape without scattering elastically. The neutrons are detected in the thicker neutron-capture layers. The location of the IBD event is determined from the energy deposited by the positron as it slows in the medium and from the two gamma rays that come from the positron annihilation. Since the neutron recoils in the direction of the antineutrino's motion, a line may then be drawn between the IBD event location and the neutron-capture location to approximate the antineutrino's velocity. In some events, we may even measure the positron's velocity, which further increases our ability to reconstruct the antineutrino's direction of motion. Our method significantly improves upon previous methods by allowing the neutron to freely travel a long distance before diffusing and being captured. Moreover, our design is a straightforward modification of existing antineutrino detectors; a prototype could easily be built with existing technology. We verify our design through Monte Carlo simulations in Geant4, using commercially-available boron-loaded plastic scintillators for the target and neutron-capture layer materials. We are able to discriminate from background using multiple coincidence signatures within a short, ~microsecond time interval. We conclude that the detector could likely operate above ground with minimal shielding.

  6. Self directed learning.

    PubMed Central

    Towle, A; Cottrell, D

    1996-01-01

    The ability to acquire skills in self directed learning may be the key link between undergraduate education, postgraduate training, and continuing professional development. If future and current practitioners are to adopt an ongoing reflective and critical approach to practice, we should aim to provide learning opportunities that promote self confidence, question asking and reflection, openness and risk taking, uncertainty and surprise. Teaching techniques that encourage these skills are being introduced widely and have been shown to be at least as effective as traditional methods of education while promoting more enjoyment and enthusiasm among both staff and students. PMID:8669942

  7. Direct to Digital Holography

    SciTech Connect

    Bingham, P.R.; Tobin, K.W.

    2003-06-15

    In this CRADA, Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, development of the first prototype named the Visible Alpha Tool (VAT) that uses visible spectrum illumination of 532 nm, assist in design of second prototype tool named the DUV Alpha Tool (DAT) using deep UV (266 nm) illumination, and continuing support of nLine in the development of higher throughput commercial tools.

  8. Direct reading inductance meter

    NASA Technical Reports Server (NTRS)

    Kolby, R. B. (inventor)

    1977-01-01

    A direct reading inductance meter comprised of a crystal oscillator and an LC tuned oscillator is presented. The oscillators function respectively to generate a reference frequency, f(r), and to generate an initial frequency, f(0), which when mixed produce a difference equal to zero. Upon connecting an inductor of small unknown value in the LC circuit to change its resonant frequency to f(x), a difference frequency (f(r)-f(x)) is produced that is very nearly a linear function of the inductance of the inductor. The difference frequency is measured and displayed on a linear scale in units of inductance.

  9. Direct effects protection

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Protection of an aircraft and each of its various systems against the direct effects of lightning were analyzed. Components located in different sections of the aircraft were individually examined since they are likely to experience different degrees of susceptibility to lightning, and may be vulnerable to different components of the lightning flash. The basic steps to be followed in establishing lightning protection were presented by discussing the varieties of arc entry and current flow-through damage. The lightning-strike zones and lightning current environments are established, since environmental conditions in the zones are those under which specific protective measures must perform. Airworthiness regulations which apply to lightning protection are cited.

  10. Pulmonary rehabilitation: future directions.

    PubMed

    Nici, Linda; ZuWallack, Richard L

    2014-06-01

    Pulmonary rehabilitation is now an established standard of care for patients with chronic obstructive pulmonary disease (COPD). Although pulmonary rehabilitation has no appreciable direct effect on static measurements of lung function, it arguably provides the greatest benefit of any available therapy across multiple outcome areas important to the patient with respiratory disease, including dyspnea, exercise performance, and health-related quality of life. It also appears to be a potent intervention that reduces COPD hospitalizations, especially when given in the periexacerbation period. The role of pulmonary rehabilitation within the larger schema of integrated care represents a fruitful area for further research. PMID:24874138

  11. Roaming Robot: Give Directions

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners investigate angles and rotation as they act out a set of commands involving going forward, backward, and making left and right turns. The "Finder" leaves the room while others hide an object. The "Finder" returns, and learners take turns choosing “commands” to lead the "Finder" to the hidden object. The activity comes with “command” sheets at three different levels of difficulty, ranging from simple directions (e.g. take 1 step backwards) to variables (e.g. take __ steps backwards). Available as a web page and downloadable pdf.

  12. Effective direction measurements for spacecraft attitude: II. Predicted directions

    NASA Astrophysics Data System (ADS)

    Shuster, Malcolm D.

    2007-12-01

    The predicted directions are examined as effective measurements of spacecraft attitude. It is shown that two linearly independent predicted directions are a sufficient statistic for the attitude, and that these two effective measurements can be chosen to be arbitrary directions as long as they are not parallel or antiparallel. However, the correct implementation of the predicted directions in maximum-likelihood estimation of the attitude is complicated by the form of the covariance matrix for each and their mutual correlation. Thus, the predicted directions, which differ greatly from the equivalent direction measurements presented earlier, are not useful as a practical vehicle for attitude data fusion. Unlike the equivalent directions, the predicted directions are always physically meaningful. Unfortunately, they are also almost physically meaningless, as we shall see. Nonetheless, they are of obvious theoretical interest and worthy of a careful examination. The predicted directions can be shown to be "equivalent" measurements for the TRIAD algorithm.

  13. In-situ FTIR-diffuse reflection study of methanol oxidation mechanisms on fuel cell anodes

    SciTech Connect

    Fan, Q.; Pu, C.; Smotkin, E.S. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical and Environmental Engineering

    1996-12-31

    The catalytic surfaces of membrane electrode assemblies in direct methanol/oxygen fuel cells were investigated in-situ by Fourier Transform Infrared-Diffuse Reflection Spectroscopy. A novel, temperature controlled (90 C), single cell fuel cell assembly with an infrared transparent window was constructed to facilitate such studies. Pt-black and Pt-Ru were studied as anode catalysts with platinum black on the cathode side. The vibrational modes observed on the surface of the methanol anodes include those of formaldehyde and formic acid. CO is the primary intermediate of methanol oxidation on Pt-black and Pt-Ru anode catalysts. The intensity of CO adsorption modes on Pt-Ru is less than o Pt-black. Formaldehyde oxidation on Pt-black produces more Co intermediate in comparison with formic acid oxidation. Possible mechanisms for methanol, formaldehyde, and formic acid oxidation on the anode surfaces are discussed.

  14. Direct Aerosol Forcing Uncertainty

    DOE Data Explorer

    Mccomiskey, Allison

    Understanding sources of uncertainty in aerosol direct radiative forcing (DRF), the difference in a given radiative flux component with and without aerosol, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: aerosol optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual aerosol or surface properties, are calculated at three locations representing distinct aerosol types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective aerosol or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.

  15. NON-DIRECTIVE PSYCHOTHERAPY

    PubMed Central

    Smith, Lloyd F.

    1950-01-01

    Psychotherapy is a word to describe an age-old process. It would be better not to speak of psychotherapy, but of psychotherapies. Specialists are not the only ones who act as psychotherapists, since every human being fills this role at one time or another. Besides this, no two persons follow an identical approach. Finally, all therapists change technique constantly. The kinds of psychotherapy must therefore approach infinity. Some physicians appear to assume that only one type of psychotherapy may claim a scientific basis. Although Freud first put psychotherapy on a scientific path, there is no reason to say that Freud must be the last in this field. Over the past few years a new trend has started in psychotherapy which deserves close study. This new trend challenges some old beliefs and gives a new tool to help patients of some types. It is called non-directive or client-centered psychotherapy. This therapy does not try to solve the patient's problems for him, but rather establishes the conditions under which a patient can work out his own salvation. Each year non-directive psychotherapy grows in importance. Much can be learned from the method. PMID:14778014

  16. Direct Aerosol Forcing Uncertainty

    SciTech Connect

    Mccomiskey, Allison

    2008-01-15

    Understanding sources of uncertainty in aerosol direct radiative forcing (DRF), the difference in a given radiative flux component with and without aerosol, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: aerosol optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual aerosol or surface properties, are calculated at three locations representing distinct aerosol types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective aerosol or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.

  17. Modeling Directional Solidification

    NASA Technical Reports Server (NTRS)

    Wilcox, W. R.; Paptheodorou, T.

    1985-01-01

    The objective of the research is to develop tools of use in explaining the results of directional solidification experiments in space. These tools consist of mathematical and experimental models. Experiments are also being flown at low-g to validate the ground-based results. Many metals and semiconductors directionally solidified in space had a diameter less than that of the containing ampoule. In fact this occurred whenever the ampoule contained a gas space. This phenomenon has been attributed in a vague way to lack of wetting of the ampoule wall by the melt. The actual liquid behavior by use of low temperature analogs is being observed aboard the KC-135. In the first flight, water was placed in plastic ampoules (not wet) with ceramic end plugs which were wet by the water to simulate a solid-liquid interface. Unfortunately during storage prior to the flight the water began to wet the ampoule wall. Discrete bubbles formed down the axis of the ampoules. New ampoule materials are being used now, with testing for stability prior to the next flight. A theoretical model has also been developed for this phenomenon.

  18. A planar bi-directional antenna with high directivities in the broadside directions

    Microsoft Academic Search

    Huan-Chu Huang; Jen-Chen Lu; Powen Hsu

    2010-01-01

    A planar bi-directional antenna with high directivities in the broadside directions on a thin FR4 dielectric substrate based on the transformation of the Yagi-Uda design rationale is proposed. This design can provide two main beams with high directivities, better than 6.0 dBi, in two broadside directions. The bandwidth is around 5.5% and efficiency of the antenna is 89.3%, which is

  19. Direct UV-written broadband directional planar waveguide couplers

    NASA Astrophysics Data System (ADS)

    Olivero, Massimo; Svalgaard, Mikael

    2005-10-01

    We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation.

  20. Buspirone: future directions.

    PubMed

    Apter, J T; Allen, L A

    1999-02-01

    The Food and Drug Administration approved the use of buspirone for generalized anxiety disorder (GAD) in 1986. Since then, numerous studies have examined the efficacy and safety of buspirone for patients with not only generalized feelings of anxiety, but also panic disorder, major depressive disorder, obsessive-compulsive disorder, body dysmorphic disorder, social phobia, posttraumatic stress disorder, selective serotonin reuptake inhibitor-induced adverse events, dementia, behavioral disturbances, attention deficit-hyperactivity disorder, and tobacco dependency. Although relatively few placebo-controlled trials have been conducted on patients with problems other than GAD, an ever-growing body of research suggests future directions for the use of buspirone. This article reviews the body of research relating to new uses for buspirone. PMID:9934947

  1. Directional antineutrino detection.

    PubMed

    Safdi, Benjamin R; Suerfu, Burkhant

    2015-02-20

    We propose the first event-by-event directional antineutrino detector using inverse beta decay (IBD) interactions on hydrogen, with potential applications including monitoring for nuclear nonproliferation, spatially mapping geoneutrinos, characterizing the diffuse supernova neutrino background and searching for new physics in the neutrino sector. The detector consists of adjacent and separated target and capture scintillator planes. IBD events take place in the target layers, which are thin enough to allow the neutrons to escape without scattering elastically. The neutrons are detected in the thicker boron-loaded capture layers. The location of the IBD event and the momentum of the positron are determined by tracking the positron's trajectory through the detector. Our design is a straightforward modification of existing antineutrino detectors; a prototype could be built with existing technology. PMID:25763953

  2. Directly estimating nonclassicality.

    PubMed

    Mari, A; Kieling, K; Nielsen, B Melholt; Polzik, E S; Eisert, J

    2011-01-01

    We establish a method of directly measuring and estimating nonclassicality--operationally defined in terms of the distinguishability of a given state from one with a positive Wigner function. It allows us to certify nonclassicality, based on possibly much fewer measurement settings than necessary for obtaining complete tomographic knowledge, and is at the same time equipped with a full certificate. We find that even from measuring two conjugate variables alone, one may infer the nonclassicality of quantum mechanical modes. This method also provides a practical tool to eventually certify such features in mechanical degrees of freedom in opto-mechanics. The proof of the result is based on Bochner's theorem characterizing classical and quantum characteristic functions and on semidefinite programming. In this joint theoretical-experimental work we present data from experimental optical Fock state preparation. PMID:21231723

  3. The direction of gravity

    NASA Astrophysics Data System (ADS)

    Linder, E. V.

    2014-03-01

    Gravity directs the paths of light rays and the growth of structure. Moreover, gravity on cosmological scales does not simply point down: It accelerates the universal expansion by pulling outward, either due to a highly negative pressure dark energy or an extension of general relativity. We have examined methods to test the properties of gravity through cosmological measurements. We have then considered specific possibilities for a sound gravitational theory based on the Galilean shift symmetry. The evolution of the laws of gravity from the early universe to the present acceleration to the future fate - the paths of gravity - carries rich information on this fundamental force of physics, and on the mystery of dark energy.

  4. Directional Antineutrino Detection

    NASA Astrophysics Data System (ADS)

    Safdi, Benjamin R.; Suerfu, Burkhant

    2015-02-01

    We propose the first event-by-event directional antineutrino detector using inverse beta decay (IBD) interactions on hydrogen, with potential applications including monitoring for nuclear nonproliferation, spatially mapping geoneutrinos, characterizing the diffuse supernova neutrino background and searching for new physics in the neutrino sector. The detector consists of adjacent and separated target and capture scintillator planes. IBD events take place in the target layers, which are thin enough to allow the neutrons to escape without scattering elastically. The neutrons are detected in the thicker boron-loaded capture layers. The location of the IBD event and the momentum of the positron are determined by tracking the positron's trajectory through the detector. Our design is a straightforward modification of existing antineutrino detectors; a prototype could be built with existing technology.

  5. Fiber optic TV direct

    NASA Astrophysics Data System (ADS)

    Kassak, John E.

    1991-12-01

    The objective of the operational television (OTV) technology was to develop a multiple camera system (up to 256 cameras) for NASA Kennedy installations where camera video, synchronization, control, and status data are transmitted bidirectionally via a single fiber cable at distances in excess of five miles. It is shown that the benefits (such as improved video performance, immunity from electromagnetic interference and radio frequency interference, elimination of repeater stations, and more system configuration flexibility) can be realized if application of the proven fiber optic transmission concept is used. The control system will marry the lens, pan and tilt, and camera control functions into a modular based Local Area Network (LAN) control network. Such a system does not exist commercially at present since the Television Broadcast Industry's current practice is to divorce the positional controls from the camera control system. The application software developed for this system will have direct applicability to similar systems in industry using LAN based control systems.

  6. Directional Antineutrino Detection

    E-print Network

    Benjamin R. Safdi; Burkhant Suerfu

    2014-10-30

    We propose the first truly directional antineutrino detector for antineutrinos above the hydrogen inverse beta decay (IBD) threshold, with potential applications including monitoring for nuclear nonproliferation, spatially mapping geo-neutrinos, characterizing the diffuse supernova neutrino background, and searching for new physics in the neutrino sector. The detector consists of adjacent and separated target and capture scintillator planes. IBD events take place in the target layers, which are thin enough to allow the neutrons to escape without scattering elastically. The neutrons are detected in the thicker, boron-loaded capture layers. The location of the IBD event and the momentum of the positron are determined by tracking the positron's trajectory through the detector. Our design is a straightforward modification of existing antineutrino detectors; a prototype could be built with existing technology.

  7. Modelling directional solidification

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.

    1990-01-01

    The long range goal is to develop an improved understanding of phenomena of importance to directional solidification, to enable explanation and prediction of differences in behavior between solidification on Earth and in space. Emphasis during the period of this grant was on experimentally determining the influence of convection and freezing rate fluctuations on compositional homogeneity and crystalline perfection in the vertical Bridgman-Stockbarger technique. Heater temperature profiles, buoyancy-driven convection, and doping inhomogeneties were correlated using naphthalene doped with azulene. In addition the influence of spin-up/spin-down on compositional homogeneity and microstructure of indium gallium antimonide and the effect of imposed melting-freezing cycles on indium gallium antimonide are discussed.

  8. Conclusions and Policy Directions,

    SciTech Connect

    Wilbanks, Thomas J [ORNL; Romero-Lankao, Paty [National Center for Atmospheric Research (NCAR); Gnatz, P [National Center for Atmospheric Research (NCAR)

    2011-01-01

    This chapter briefly revisits the constraints and opportunities of mitigation and adaptation, and highlights and the multiple linkages, synergies and trade-offs between mitigation, adaptation and urban development. The chapter then presents future policy directions, focusing on local, national and international principles and policies for supporting and enhancing urban responses to climate change. In summary, policy directions for linking climate change responses with urban development offer abundant opportunities; but they call for new philosophies about how to think about the future and how to connect different roles of different levels of government and different parts of the urban community. In many cases, this implies changes in how urban areas operate - fostering closer coordination between local governments and local economic institutions, and building new connections between central power structures and parts of the population who have often been kept outside of the circle of consultation and discourse. The difficulties involved in changing deeply set patterns of interaction and decision-making in urban areas should not be underestimated. Because it is so difficult, successful experiences need to be identified, described and widely publicized as models for others. However, where this challenge is met, it is likely not only to increase opportunities and reduce threats to urban development in profoundly important ways, but to make the urban area a more effective socio-political entity, in general - a better city in how it works day to day and how it solves a myriad of problems as they emerge - far beyond climate change connections alone. It is in this sense that climate change responses can be catalysts for socially inclusive, economically productive and environmentally friendly urban development, helping to pioneer new patterns of stakeholder communication and participation.

  9. Directionally Solidified Ceramics Produced

    NASA Technical Reports Server (NTRS)

    Farmer, Serene C.; Sayir, Ali

    2000-01-01

    Produced Multiphase, interpenetrating structures are an alternative route to obtaining structural ceramic materials with adequate strength, toughness, and stability for high-temperature aerospace applications. The eutectic architecture, a continuous-reinforcing phase within a higher volume phase or matrix, can be described as a naturally occurring, in situ composite. The phases of a eutectic are thermodynamically compatible at high homologous temperatures. Strong and stable materials have been produced. Toughness, however, remains a technical obstacle. The potential for producing materials with enhanced toughness along with adequate strength and stability was demonstrated using the laser-heated float zone (LHFZ) growth method at the NASA Glenn Research Center at Lewis Field. LHFZ growth at Glenn provides a means to efficiently produce and record the underlying growth phenomena associated with two-phase structures. To initiate directional solidification, a seed of single-crystal sapphire (<0001> direction) was lowered onto the molten liquid until wetting occurred and then withdrawn at a constant rate. Neither the crystal nor the source rod was rotated. The materials produced were tested mechanically in tension, and the resulting microstructure was examined with a scanning electron microscope. Both the inherent properties of the constituent phases and the properties of the interface between them affect the mechanical behavior and the fracture surfaces. The following scanning electron micrographs show the microstructures of two different materials that were tested to failure in tension. In the left micrograph, the flat fracture surface is typical of a material that is strong but has low toughness. In the right micrograph, the crack is effectively deflected at the interface between the two phases, achieving higher toughness at moderately lower strength levels. Conducting mechanical tests to determine the high temperature properties of these materials is the next step in determining their eventual suitability.

  10. Explosive Percolation in Directed Networks

    E-print Network

    Anlage, Steven

    Explosive Percolation in Directed Networks Diego Alcala and Katherine Sytwu With Shane Squires ­ Directed and undirected networks ­ Percolation ­ Explosive percolation · Methodology · Results · Conclusion, infrastructure, etc. · Grow by the addition of links · New class of transitions: "explosive percolation" Taken

  11. Direct cupration of fluoroform.

    PubMed

    Zanardi, Alessandro; Novikov, Maxim A; Martin, Eddy; Benet-Buchholz, Jordi; Grushin, Vladimir V

    2011-12-28

    We have found the first reaction of direct cupration of fluoroform, the most attractive CF(3) source for the introduction of the trifluoromethyl group into organic molecules. Treatment of CuX (X = Cl, Br, I) with 2 equiv of MOR (M = K, Na) in DMF or NMP produces novel alkoxycuprates that readily react with CF(3)H at room temperature and atmospheric pressure to give CuCF(3) derivatives. The CuCl and t-BuOK (1:2) combination provides best results, furnishing the CuCF(3) product within seconds in nearly quantitative yield. As demonstrated, neither CF(3)(-) nor CF(2) mediate the Cu-CF(3) bond formation, which accounts for its remarkably high selectivity. The fluoroform-derived CuCF(3) solutions can be efficiently stabilized with TREAT HF to produce CuCF(3) reagents that readily trifluoromethylate organic and inorganic electrophiles in the absence of additional ligands such as phenanthroline. A series of novel Cu(I) complexes have been structurally characterized, including K(DMF)[Cu(OBu-t)(2)] (1), Na(DMF)(2)[Cu(OBu-t)(2)] (2), [K(8)Cu(6)(OBu-t)(12)(DMF)(8)(I)](+) I(-) (3), and [Cu(4)(CF(3))(2)(C(OBu-t)(2))(2)(?(3)-OBu-t)(2)] (7). PMID:22136628

  12. Directionally solidified mullite fibers

    SciTech Connect

    Sayir, A. [Case Western Reserve Univ., Cleveland, OH (United States); Farmer, S.C. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center

    1995-10-01

    Directionally solidified fibers with nominal mullite compositions of 3Al{sub 2}O{sub 3} {center_dot} 2SiO{sub 2} were grown by the laser heated float zone (LHFZ) method at NASA Lewis. High resolution digital images from an optical microscope evidence the formation of a liquid-liquid miscibility gap during crystal growth. Experimental evidence shows that the formation of mullite in aluminosilicate melts is in fact preceded by liquid immiscibility. The average fiber tensile strength is 1.15 GPa at room temperature. The mullite fibers retained 80% of their room temperature tensile strength at 1,450 C. SEM analysis revealed that the fibers were strongly faceted and that the facets act as critical flaws. Examined in TEM, these mullite single crystals are free of dislocations, low angle boundaries and voids. Single crystal mullite showed a high degree of oxygen vacancy ordering. Regardless of the starting composition, the degree of order observed in polycrystalline fibers was lower than that observed in the mullite single crystals.

  13. Crawling on directional surfaces

    E-print Network

    Paolo Gidoni; Giovanni Noselli; Antonio DeSimone

    2014-01-23

    In this paper we study crawling locomotion based on directional frictional interactions, namely, frictional forces that are sensitive to the sign of the sliding velocity. Surface interactions of this type are common in biology, where they arise from the presence of inclined hairs or scales at the crawler/substrate interface, leading to low resistance when sliding 'along the grain', and high resistance when sliding 'against the grain'. This asymmetry can be exploited for locomotion, in a way analogous to what is done in cross-country skiing (classic style, diagonal stride). We focus on a model system, namely, a continuous one-dimensional crawler and provide a detailed study of the motion resulting from several strategies of shape change. In particular, we provide explicit formulae for the displacements attainable with reciprocal extensions and contractions (breathing), or through the propagation of extension or contraction waves. We believe that our results will prove particularly helpful for the study of biological crawling motility and for the design of bio-mimetic crawling robots.

  14. Multiple direction vibration fixture

    DOEpatents

    Cericola, Fred (Albuquerque, NM); Doggett, James W. (Albuquerque, NM); Ernest, Terry L. (Albuquerque, NM); Priddy, Tommy G. (Rockville, MD)

    1991-01-01

    An apparatus for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 degrees around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis.

  15. New Directions in Biotechnology

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The macromolecule crystallization program within NASA is undergoing considerable pressure, particularly budgetary pressure. While it has shown some successes, they have not lived up to the expectations of others, and technological advances may rapidly overtake the natural advantages offered by crystallization in microgravity. Concomitant with the microgravity effort has been a research program to study the macromolecule crystallization process. It was believed that a better understanding of the process would lead to growth of improved crystals for X-ray diffraction studies. The results of the various research efforts have been impressive in improving our understanding of macromolecule crystallization, but have not led to any improved structures. Macromolecule crystallization for structure determination is "one of", the job being unique for every protein and finished once a structure is obtained. However, the knowledge gained is not lost, but instead lays the foundation for developments in new areas of biotechnology and nanotechnology. In this it is highly analogous to studies into small molecule crystallization, the results of which have led to our present day microelectronics-based society. We are conducting preliminary experiments into areas such as designed macromolecule crystals, macromolecule-inorganic hybrid structures, and macromolecule-based nanotechnology. In addition, our protein crystallization studies are now being directed more towards industrial and new approaches to membrane protein crystallization.

  16. 78 FR 32533 - Proposed Collection of Information: Direct Deposit, Go Direct, and Direct Express Sign-Up Forms

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-30

    ...Collection of Information: Direct Deposit, Go Direct, and Direct Express Sign-Up Forms...Deposit Sign-Up Form'', Form 1200 ``Go Direct Sign-Up Form for Direct Deposit...Title: Direct Deposit Sign-Up Form, and Go Direct Sign-Up Form, and Direct...

  17. Geometry of directions

    NASA Astrophysics Data System (ADS)

    Leung, Shih-Chieh

    A new parallel implicit adaptive mesh refinement (AMR) algorithm is developed for the prediction of unsteady behaviour of laminar flames. The scheme is applied to the solution of the system of partial-differential equations governing time-dependent, two- and three-dimensional, compressible laminar flows for reactive thermally perfect gaseous mixtures. A high-resolution finite-volume spatial discretization procedure is used to solve the conservation form of these equations on body-fitted multi-block hexahedral meshes. A local preconditioning technique is used to remove numerical stiffness and maintain solution accuracy for low-Mach-number, nearly incompressible flows. A flexible block-based octree data structure has been developed and is used to facilitate automatic solution-directed mesh adaptation according to physics-based refinement criteria. The data structure also enables an efficient and scalable parallel implementation via domain decomposition. The parallel implicit formulation makes use of a dual-time-stepping like approach with an implicit second-order backward discretization of the physical time, in which a Jacobian-free inexact Newton method with a preconditioned generalized minimal residual (GMRES) algorithm is used to solve the system of nonlinear algebraic equations arising from the temporal and spatial discretization procedures. An additive Schwarz global preconditioner is used in conjunction with block incomplete LU type local preconditioners for each sub-domain. The Schwarz preconditioning and block-based data structure readily allow efficient and scalable parallel implementations of the implicit AMR approach on distributed-memory multi-processor architectures. The scheme was applied to solutions of steady and unsteady laminar diffusion and premixed methane-air combustion and was found to accurately predict key flame characteristics. For a premixed flame under terrestrial gravity, the scheme accurately predicted the frequency of the natural buoyancy induced oscillations. The performance of the proposed parallel implicit algorithm was assessed by comparisons to more conventional solution procedures and was found to significantly reduce the computational time required to achieve a solution in all cases investigated.

  18. Dynamic behaviors in directed networks

    NASA Astrophysics Data System (ADS)

    Park, Sung Min; Kim, Beom Jun

    2006-08-01

    Motivated by the abundance of directed synaptic couplings in a real biological neuronal network, we investigate the synchronization behavior of the Hodgkin-Huxley model in a directed network. We start from the standard model of the Watts-Strogatz undirected network and then change undirected edges to directed arcs with a given probability, still preserving the connectivity of the network. A generalized clustering coefficient for directed networks is defined and used to investigate the interplay between the synchronization behavior and underlying structural properties of directed networks. We observe that the directedness of complex networks plays an important role in emerging dynamical behaviors, which is also confirmed by a numerical study of the sociological game theoretic voter model on directed networks.

  19. Teaching with satellite direct readout

    Microsoft Academic Search

    T. W. Wagner; J. H. Gibson

    1994-01-01

    Increasingly, educators in schools in the United States and in other countries are using the direct readout of satellite data to stimulate science, mathematics, and technology learning by their students. Direct readout of Automatic Picture Transmission (APT) and Weather-Facsimile (WEFAX) images involves only a modest investment in school-fabricated and\\/or off-the-shelf equipment, but allows students to plug directly into one of

  20. The Influence of Directional Associations on Directed Forgetting and Interference

    ERIC Educational Resources Information Center

    Sahakyan, Lili; Goodmon, Leilani B.

    2007-01-01

    Two experiments examined how cross-list directional associations influenced list-method directed forgetting and the degree of interference observed on each list. Each List 1 item had a (a) bidirectionally related item on List 2 (chip ?? potato), (b) forward association with an item on List 2 (chip ? wood), (c) backward association from an item on…

  1. Direct UV-written broadband directional planar waveguide couplers.

    PubMed

    Olivero, Massimo; Svalgaard, Mikael

    2005-10-17

    We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation. PMID:19498869

  2. A direct test of direct democracy: New England town meetings

    Microsoft Academic Search

    Robert Salvino; Michael T. Tasto; Geoffrey K. Turnbull

    2012-01-01

    Representative democracies govern most locales in the US, making it difficult to compare performance relative to direct democracy. New England states, however, provide an opportunity to test both direct and representative democracy at the local level. This article uses revealed preference axioms to compare spending patterns in New England towns and cities against median voter hypothesis benchmarks. Contrary to previous

  3. A direct test of direct democracy: New England town meetings

    Microsoft Academic Search

    Robert Salvino; Michael T. Tasto; Geoffrey K. Turnbull

    2011-01-01

    Representative democracies govern most locales in the US, making it difficult to compare performance relative to direct democracy. New England states, however, provide an opportunity to test both direct and representative democracy at the local level. This article uses revealed preference axioms to compare spending patterns in New England towns and cities against median voter hypothesis benchmarks. Contrary to previous

  4. Direct cooled power electronics substrate

    DOEpatents

    Wiles, Randy H [Powell, TN; Wereszczak, Andrew A [Oak Ridge, TN; Ayers, Curtis W. (Kingston, TN) [Kingston, TN; Lowe, Kirk T. (Knoxville, TN) [Knoxville, TN

    2010-09-14

    The disclosure describes directly cooling a three-dimensional, direct metallization (DM) layer in a power electronics device. To enable sufficient cooling, coolant flow channels are formed within the ceramic substrate. The direct metallization layer (typically copper) may be bonded to the ceramic substrate, and semiconductor chips (such as IGBT and diodes) may be soldered or sintered onto the direct metallization layer to form a power electronics module. Multiple modules may be attached to cooling headers that provide in-flow and out-flow of coolant through the channels in the ceramic substrate. The modules and cooling header assembly are preferably sized to fit inside the core of a toroidal shaped capacitor.

  5. Applications of payload directed flight

    Microsoft Academic Search

    Corey Ippolito; Matt Fladeland; Yoo Hsiu Yeh

    2009-01-01

    Next generation aviation flight control concepts require autonomous and intelligent control system architectures that close control loops directly around payload sensors in manner more integrated and cohesive that in traditional autopilot designs. Research into payload and sensor directed flight control at NASA Ames Research Center is investigating new and novel architectures that can satisfy the requirements for next generation control

  6. Direct Sum Decomposition of Groups

    ERIC Educational Resources Information Center

    Thaheem, A. B.

    2005-01-01

    Direct sum decomposition of Abelian groups appears in almost all textbooks on algebra for undergraduate students. This concept plays an important role in group theory. One simple example of this decomposition is obtained by using the kernel and range of a projection map on an Abelian group. The aim in this pedagogical note is to establish a direct

  7. Fifth Biennial Conference New Directions

    E-print Network

    Bushman, Frederic

    Fifth Biennial Conference New Directions in Biology and Disease of Skeletal Muscle Conference 2012 http://www.med.upenn.edu/muscle #12;Objective in Biology and Disease of Skeletal Muscle Conference June Straub, MD, PhD, University of Newcastle, UK Kathryn Wagner, MD, PhD, The New Directions in Biology

  8. Problematic Directives in Pedagogical Interaction

    ERIC Educational Resources Information Center

    Waring, Hansun Zhang; Hruska, Barbara L.

    2012-01-01

    Directives are integral to teachers' pedagogical repertoire, and their efficacy crucial to optimizing learning outcomes. Based on data from a videotaped tutoring session collected at an after-school early literacy program, we describe the specific ways in which certain practices of directives can hinder learner participation and compromise…

  9. Optically broadcasting wind direction indicator

    NASA Astrophysics Data System (ADS)

    Zysko, Jan A.

    1994-10-01

    An optically broadcasting wind direction indicator generates flashes of light which are separated by a time interval that is directly proportional to the angle of the wind direction relative to a fixed direction, such as north. An angle/voltage transducer generates a voltage that is proportional to the wind direction relative to the fixed direction, and this voltage is employed by timing circuitry or a microprocessor that generates pulses for actuating a light source trigger circuit first at the start of the time interval, and then at the end of the time interval. To aid an observer in distinguishing between the beginning and end of the interval, two stop flashes can be provided in quick succession. The time scale is preferably chosen so that each second of the time interval corresponds to 30 deg of direction relative to north. In this manner, an observer can easily correlate the measured time interval to the wind direction by visualizing the numbers on a conventional clock face, each of which correspond to one second of time and 30 deg of angle.

  10. Modeling Data using Directional Distributions

    Microsoft Academic Search

    Inderjit S. Dhillon; Suvrit Sra

    2003-01-01

    Traditionally multi-variate normal distributions have been the staple of data modeling in most domains. For some domains, the model they provide is either inadequate or incorrect because of the disregard for the directional components of the data. We present a generative model for data that is suitable for modeling directional data (as can arise in text and gene expression clustering).

  11. Epidemic threshold in directed networks.

    PubMed

    Li, Cong; Wang, Huijuan; Van Mieghem, Piet

    2013-12-01

    Epidemics have so far been mostly studied in undirected networks. However, many real-world networks, such as the online social network Twitter and the world wide web, on which information, emotion, or malware spreads, are directed networks, composed of both unidirectional links and bidirectional links. We define the directionality ? as the percentage of unidirectional links. The epidemic threshold ?(c) for the susceptible-infected-susceptible (SIS) epidemic is lower bounded by 1/?(1) in directed networks, where ?(1), also called the spectral radius, is the largest eigenvalue of the adjacency matrix. In this work, we propose two algorithms to generate directed networks with a given directionality ?. The effect of ? on the spectral radius ?(1), principal eigenvector x(1), spectral gap (?(1)-|?(2)|), and algebraic connectivity ?(N-1) is studied. Important findings are that the spectral radius ?(1) decreases with the directionality ?, whereas the spectral gap and the algebraic connectivity increase with the directionality ?. The extent of the decrease of the spectral radius depends on both the degree distribution and the degree-degree correlation ?(D). Hence, in directed networks, the epidemic threshold is larger and a random walk converges to its steady state faster than that in undirected networks with the same degree distribution. PMID:24483506

  12. Effective direction measurements for spacecraft attitude: I. Equivalent directions

    NASA Astrophysics Data System (ADS)

    Shuster, Malcolm D.

    2007-12-01

    The equivalent directions are a set of three unit vectors, conforming to the QUEST measurement model, which can lead in maximum-likelihood estimation to any given attitude estimate and attitude covariance matrix. Since they conform to the QUEST measurement model (i.e., are "QUEST-like"), the equivalent directions can be used not only in general estimation problems but also directly in the Wahba problem. It can be shown that three equivalent directions can always be found, and that they are unique within signs if the eigenvalues of the attitude co-information matrix are non-degenerate, but that the equivalent inverse variances for these equivalent directions may not always be non-negative, hence, not always physically meaningful. This can occur, for example, for attitude covariance matrices computed by the TRIAD algorithm for QUEST-like inputs. The equivalent inverse variances for attitude covariance matrices computed from original QUEST-like measurements will always be non-negative. The connection of the equivalent directions and inverse variances to Markley's SVD algorithm is presented. While not a practical vehicle for data fusion, the equivalent directions and their equivalent inverse variances can provide a useful tool for the analysis of attitude systems in data fusion problems and in mission design.

  13. Efficient Placement of Directional Antennas

    SciTech Connect

    Pan, Feng [Los Alamos National Laboratory; Kasiviswanathan, Shiva [Los Alamos National Laboratory

    2010-09-20

    Directional antenna is an technology for the proliferation of wireless networks. In centralized wireless network, wireless devices communicate through base stations. Directed antennas are placed on base stations and form a backbone of communication. The communication between base stations and wireless devices can be interfered due to a large number of wireless device. Methodically positioning and orienting directed antennas can help to reduce the interference while saving energy. An integer linear programming is developed for siting and directing antennas on multiple base stations, and this formulation can be extended to model non-overlapping channels. Through the integer programming formulation, optimal antenna positions can be used to analyze the performance of directed antennas with different parameters like the number base stations and the number of non-overlapping channels.

  14. Our purpose and direction Our purpose and direction

    E-print Network

    organisation 8 Our People 8 Our finances 8 Business sustainability ­ `Greenerways' 9 OUR DIRECTION 10 Our Woodland based learning and sector skills 35 Urban woodlands and trees 38 A COMPETITIVE AND INTEGRATED

  15. Direct Manipulation in Virtual Reality

    NASA Technical Reports Server (NTRS)

    Bryson, Steve

    2003-01-01

    Virtual Reality interfaces offer several advantages for scientific visualization such as the ability to perceive three-dimensional data structures in a natural way. The focus of this chapter is direct manipulation, the ability for a user in virtual reality to control objects in the virtual environment in a direct and natural way, much as objects are manipulated in the real world. Direct manipulation provides many advantages for the exploration of complex, multi-dimensional data sets, by allowing the investigator the ability to intuitively explore the data environment. Because direct manipulation is essentially a control interface, it is better suited for the exploration and analysis of a data set than for the publishing or communication of features found in that data set. Thus direct manipulation is most relevant to the analysis of complex data that fills a volume of three-dimensional space, such as a fluid flow data set. Direct manipulation allows the intuitive exploration of that data, which facilitates the discovery of data features that would be difficult to find using more conventional visualization methods. Using a direct manipulation interface in virtual reality, an investigator can, for example, move a data probe about in space, watching the results and getting a sense of how the data varies within its spatial volume.

  16. Module bay with directed flow

    DOEpatents

    Torczynski, John R. (Albuquerque, NM)

    2001-02-27

    A module bay requires less cleanroom airflow. A shaped gas inlet passage can allow cleanroom air into the module bay with flow velocity preferentially directed toward contaminant rich portions of a processing module in the module bay. Preferential gas flow direction can more efficiently purge contaminants from appropriate portions of the module bay, allowing a reduced cleanroom air flow rate for contaminant removal. A shelf extending from an air inlet slit in one wall of a module bay can direct air flowing therethrough toward contaminant-rich portions of the module bay, such as a junction between a lid and base of a processing module.

  17. Directional fast-neutron detector

    DOEpatents

    Byrd, Roger C. (Albuquerque, NM)

    1994-01-01

    A plurality of omnidirectional radiation detectors are arranged in a close packed symmetrical pattern to form a segmented detector. The output radiation counts from these detectors are arithmetically combined to provide the direction of a source of incident radiation. Directionality is achieved without the use of shielding to provide collimation and background reduction effects. Indeed, output counts from paired detectors are simply subtracted to yield a vector direction toward the radiation source. The counts from all of the detectors can be combined to yield an output signal functionally related to the radiation source strength.

  18. Offshoring and Directed Technical Change

    E-print Network

    Acemoglu, Daron

    2012-11-24

    To study the short-run and long-run implications on wage inequality, we introduce directed technical change into a Ricardian model of offshoring. A unique final good is produced by combining a skilled and an unskilled ...

  19. Directive Teaching in the Classroom

    ERIC Educational Resources Information Center

    Stephens, Thomas M.

    1974-01-01

    Five steps in directive teaching are delineated: a) select target children; b) identify target behaviors; c) identify reinforcing events; d) establish plan, including instructional goals, reinforcement, and reward schedule; and e) implement and evaluate. (HMD)

  20. RICE UNIVERSITY BEAMSWITCH: DIRECTIONAL TRANSMISSION

    E-print Network

    Zhong, Lin

    RICE UNIVERSITY BEAMSWITCH: DIRECTIONAL TRANSMISSION FOR ENERGY-EFFICIENT WIRELESS COMMUNICATION guidance and support throughout my research and study at Rice. This work would not be possible without his

  1. Direct Broadcast Satellite: Radio Program

    NASA Technical Reports Server (NTRS)

    Hollansworth, James E.

    1992-01-01

    NASA is committed to providing technology development that leads to the introduction of new commercial applications for communications satellites. The Direct Broadcast Satellite-Radio (DBS-R) Program is a joint effort between The National Aeronautics and Space Administration (NASA) and The United States Information Agency/Voice of America (USIA/VOA) directed at this objective. The purpose of this program is to define the service and develop the technology for a direct-to-listener satellite sound broadcasting system. The DBS-R Program, as structured by NASA and VOA, is now a three-phase program designed to help the U.S. commercial communications satellite and receiver industry bring about this new communications service. Major efforts are being directed towards frequency planning hardware and service development, service demonstration, and experimentation with new satellite and receiver technology.

  2. Directional impedance of geared transmissions

    E-print Network

    Wang, Albert Duan

    2012-01-01

    The purpose of this research is to develop a design tool for geared actuation systems that experience bidirectional exchange of energy with the environment. Despite the asymmetry of efficiency depending on the direction ...

  3. Directions for improved fusion reactors

    Microsoft Academic Search

    R. A. Krakowski; R. L. Miller; J. G. Delene

    1986-01-01

    Conceptual fusion reactor studies over the past 10 to 15 years have projected systems that may be too large, complex, and costly to be of commercial interest. One main direction for improved fusion reactors points towards smaller, higher-power-density approaches. First-order economic issues (i.e., unit direct cost and cost of electricity) are used to support the need for more compact fusion

  4. Examined the direct carburizing method

    SciTech Connect

    Naito, T. [Dowa Mining Co., Ltd., Yokohama (Japan); Ogihara, K. [Dowa Mining Co., Ltd., Hamamatsu (Japan)

    1995-12-31

    The endothermic gas carburizing method, where air and methane, propane or butane gas are mixed and generated, has been operated for over 40 years at least. The mechanism of the endothermic gas carburizing method has already been solved and is known. The other method, the direct carburizing method by flowing hydrocarbon gas into a carburizing furnace directly without using the gas generator, has been recently adopted and popular from the point of saving energy.

  5. Direct \\

    Microsoft Academic Search

    GEORGE L. HODY; JAMES J. KACIRK; ANDREW A. PILMANIS

    1973-01-01

    Thermal insulation is one of the most critical components involved in life support in a large number of operations undersea. The degree to which thermal insulation is effective in blocking the flow of heat depends both upon its properties and also upon the environment. For example; the common closed cell wet-suit material compresses and loses efficiency as a function of

  6. Directions.

    ERIC Educational Resources Information Center

    Manning, Helen H.

    To examine the current status of speech and theatre departments in small (1000 to 3000 students) U.S. liberal arts colleges, 24 colleges in the Midwest and Great Lakes areas were surveyed. The survey revealed that the colleges organized speech and theatre in one of four ways; they either (1) combined departments, (2) split the two into separate…

  7. Asymmetric Wettability Directs Leidenfrost Droplets

    SciTech Connect

    Agapov, Rebecca L [ORNL] [ORNL; Boreyko, Jonathan B [ORNL] [ORNL; Briggs, Dayrl P [ORNL] [ORNL; Srijanto, Bernadeta R [ORNL] [ORNL; Retterer, Scott T [ORNL] [ORNL; Collier, Pat [ORNL] [ORNL; Lavrik, Nickolay V [ORNL] [ORNL

    2014-01-01

    Leidenfrost phenomena on nano- and microstructured surfaces are of great importance for increasing control over heat transfer in high power density systems utilizing boiling phenomena. They also provide an elegant means to direct droplet motion in a variety of recently emerging fluidic systems. Here, we report the fabrication and characterization of tilted nanopillar arrays (TNPAs) that exhibit directional Leidenfrost water droplets under dynamic conditions, namely on impact with Weber numbers 40 at T 325 C. The batch fabrication of the TNPAs was achieved by glancing-angle anisotropic reactive ion etching of a thermally dewet platinum mask, with mean pillar diameters of 100 nm and heights of 200-500 nm. In contrast to previously implemented macro- and microscopic Leidenfrost ratchets, our TNPAs induce no preferential directional movement of Leidenfrost droplets under conditions approaching steady-state film boiling, suggesting that the observed droplet directionality is not a result of asymmetric vapor flow. Using high-speed imaging, phase diagrams were constructed for the boiling behavior upon impact for droplets falling onto TNPAs, straight nanopillar arrays, and smooth silicon surfaces. The asymmetric impact and directional trajectory of droplets was exclusive to the TNPAs for impacts corresponding to the transition boiling regime, revealing that asymmetric wettability upon impact is the mechanism for the droplet directionality.

  8. Directional Lapped Transforms for Image Coding

    Microsoft Academic Search

    Jizheng Xu; Feng Wu; Jie Liang; Wenjun Zhang

    2008-01-01

    This paper presents a scheme to design directional lapped transforms. Lapped transforms can be factorized into lifting steps. By introducing directional operator into each lifting step, the directional lapped transform is constructed. The directional lapped transform proposed not only preserves the advantages of lapped transforms, it also can represent directional signals more efficiently. An image coding scheme using the directional

  9. Our purpose and direction Our purpose and direction

    E-print Network

    8 Our People 8 Our finances 8 Business sustainability ­ `Greenerways' 9 OUR DIRECTION 10 Our corporate programmes and performance measures 11 Our corporate programmes and Woodlands for Wales themes 12-14, the second annual update of the Corporate Plan for Forestry Commission Wales since the Welsh Assembly

  10. New directions in space electronics

    NASA Technical Reports Server (NTRS)

    Kurzhals, P. R.

    1977-01-01

    Five new directions in space electronics are defined to yield improvements over present means: automated operations aimed at a tenfold reduction in mission support costs, precision pointing and control, efficient data acquisition to permit the tenfold increase in information collection needed for global coverage, real-time data management, and low-cost data distribution to allow a thousand-fold increase in information availability and space-systems effectiveness. Technological developments and resources for each of the new directions are derived from space-technology and space-theme workshops. One to two order of magnitude improvements in instrument pointing stability will be necessary for Shuttle and planetary payloads of the 1980s. Low-cost user terminals will involve technological addressing both near-term and long-term applications. NASA has reoriented its research and technology-base programs to support the goals represented by the new directions in space electronics. Numerous charts and schematic diagrams supplement the text.

  11. The AISI direct steelmaking program

    SciTech Connect

    Aukrust, E. (LTV Steel Co., Inc., Cleveland, OH (United States)); Downing, K.B. (Inland Steel Flat Products Co. (United States))

    1991-01-01

    After six months of operation of the pilot plant, the viability of in-bath smelting combined with a high level of post combustion has been demonstrated, and the opportunity exists for an early commercialization of the direct ironmaking part of the process while we continue to research direct steelmaking. The program should be of equal interest to integrated and electric furnace producers. Smelting of ore provides virgin iron units. Additionally, the process has the flexibility of melting scrap and varying the ore-to-scrap ratio over wide ranges. This process does not require coke, thus eliminating the cokemaking operation, a major source of environmental concern.

  12. Biocatalyst Development by Directed Evolution

    PubMed Central

    Wang, Meng; Si, Tong; Zhao, Huimin

    2012-01-01

    Biocatalysis has emerged as a great addition to traditional chemical processes for production of bulk chemicals and pharmaceuticals. To overcome the limitations of naturally occurring enzymes, directed evolution has become the most important tool for improving critical traits of biocatalysts such as thermostability, activity, selectivity, and tolerance towards organic solvents for industrial applications. Recent advances in mutant library creation and high-throughput screening have greatly facilitated the engineering of novel and improved biocatalysts. This review provides an update of the recent developments in the use of directed evolution to engineer biocatalysts for practical applications. PMID:22310212

  13. Directional drilling and earth curvature

    SciTech Connect

    Williamson, H.S.; Wilson, H.F.

    2000-03-01

    This paper provides a review of current practices for calculating directional drilling placement in the light of modern extended-reach applications. The review highlights the potential for gross errors in the application of geodetic reference information and errors inherent in the calculation method. Both types of error are quantified theoretically and illustrated with a real example. The authors borrow established land surveying calculation methods to develop a revised best practice for directional drilling. For the elimination of gross errors they prescribe increased awareness and a more disciplined approach to the handling of positional data.

  14. Directional collision avoidance in ad hoc networks

    Microsoft Academic Search

    Yu Wang; Jose Joaquin Garcia-luna-aceves

    2004-01-01

    This paper analyzes the performance of directional collision avoidance schemes, in which antenna systems are used to direct the transmission and reception of control and data packets in channel access protocols based on four-way handshakes to try to avoid collisions. The first analytical model to consider directional reception and the possible difference in gain between omni-directional and directional transmissions is

  15. Entrance Counseling Guide for Direct Loan Borrowers

    ERIC Educational Resources Information Center

    Federal Student Aid, US Department of Education, 2010

    2010-01-01

    This guide describes the four types of loans offered by the Direct Loan Program[SM]: (1) Direct Subsidized Loans; (2) Direct Unsubsidized Loans; (3) Direct PLUS Loans; and (4) Direct Consolidation Loans. Among the topics covered in the guide are: Use of Your Loan Money, The Master Promissory Note, How Your Loans Will Be Disbursed (Paid Out),…

  16. Direct Measurement of Light Waves

    Microsoft Academic Search

    E. Goulielmakis; M. Uiberacker; R. Kienberger; A. Baltuska; V. Yakovlev; A. Scrinzi; Th. Westerwalbesloh; U. Kleineberg; U. Heinzmann; M. Drescher; F. Krausz

    2004-01-01

    The electromagnetic field of visible light performs ~1015 oscillations per second. Although many instruments are sensitive to the amplitude and frequency (or wavelength) of these oscillations, they cannot access the light field itself. We directly observed how the field built up and disappeared in a short, few-cycle pulse of visible laser light by probing the variation of the field strength

  17. Self directed and lifelong learning.

    PubMed

    Alexander, Sylvia; Kernohan, George; McCullagh, Paul

    2004-01-01

    Given the many changes that occur in medicine, health care and information technologies we need to prepare all our students to engage in self directed and life long learning. There is considerable opportunity for self-directed and lifelong learning in health informatics bringing together students in exciting global learning environments, where they have much greater freedom and flexibility in their studies and potentially a wider variety of resources available to them. Self-directed learning focuses on the process by which adults take control of their own learning, in particular how they set their own learning goals, locate appropriate resources, decide on which learning methods to use and evaluate their progress. Lifelong learning happens in a variety of formal and informal settings building on both intentional and incidental learning experiences. In a lifelong learning situation the tutor must relinquish the role of expert and assume the role of facilitator, guiding learners to uncover their own knowledge. Against a back drop of rapid advances in technology which can be used to both deliver course materials and provide enhanced learning opportunities, this chapter outlines the pedagogic principles and practices which underpin self-directed and lifelong learning. PMID:15718681

  18. Laboratory-Directed Protein Evolution

    PubMed Central

    Yuan, Ling; Kurek, Itzhak; English, James; Keenan, Robert

    2005-01-01

    Systematic approaches to directed evolution of proteins have been documented since the 1970s. The ability to recruit new protein functions arises from the considerable substrate ambiguity of many proteins. The substrate ambiguity of a protein can be interpreted as the evolutionary potential that allows a protein to acquire new specificities through mutation or to regain function via mutations that differ from the original protein sequence. All organisms have evolutionarily exploited this substrate ambiguity. When exploited in a laboratory under controlled mutagenesis and selection, it enables a protein to “evolve” in desired directions. One of the most effective strategies in directed protein evolution is to gradually accumulate mutations, either sequentially or by recombination, while applying selective pressure. This is typically achieved by the generation of libraries of mutants followed by efficient screening of these libraries for targeted functions and subsequent repetition of the process using improved mutants from the previous screening. Here we review some of the successful strategies in creating protein diversity and the more recent progress in directed protein evolution in a wide range of scientific disciplines and its impacts in chemical, pharmaceutical, and agricultural sciences. PMID:16148303

  19. Corruption and Foreign Direct Investment

    Microsoft Academic Search

    Mohsin Habib; Leon Zurawicki

    2002-01-01

    This study examines the impact of corruption on foreign direct investment (FDI). First, the level of corruption in the host country is analyzed. Second, the absolute difference in the corruption level between the host and home country is examined. The analysis provides support for the negative impacts of both. The results suggest that foreign investors generally avoid corruption because it

  20. Competition for foreign direct investments

    Microsoft Academic Search

    Pertti Haaparanta

    1996-01-01

    This paper models international competition for foreign direct investment as a common agency problem using the theory of menu auctions developed by Bernheim and Whinston. In the model, national governments act as principals and a multinational corporation as the single agent. Governments are assumed to maximize the net wage income generated by the corporation's investment. It is shown that in

  1. Survey on Directed Model Checking

    Microsoft Academic Search

    Stefan Edelkamp; Viktor Schuppan; Dragan Bosnacki; Anton Wijs; Ansgar Fehnker; Husain Aljazzar

    2008-01-01

    This article surveys and gives historical accounts to the al- gorithmic essentials of directed model checking, a promising bug-hunting technique to mitigate the state explosion problem. In the enumeration process, successor selection is prioritized. We discuss existing guidance and methods to automatically generate them by exploiting system ab- stractions. We extend the algorithms to feature partial-order reduction and show how

  2. Direct sequence spread spectrum signalling

    Microsoft Academic Search

    A. K. Jain

    1978-01-01

    The problems encountered in the Direct Sequence Spread Spectrum coding for communication systems employing widely distributed radio elements, providing area coverage, using higher order modulation techniques, multiple data rates, and requiring multiple access are addressed. A simple baseband correlation model which is subsequently modified to allow baseband correlation of higher order modulations is presented. Suitable algorithms are developed to generate

  3. Direction discriminating hearing aid system

    NASA Technical Reports Server (NTRS)

    Jhabvala, M.; Lin, H. C.; Ward, G.

    1991-01-01

    A visual display was developed for people with substantial hearing loss in either one or both ears. The system consists of three discreet units; an eyeglass assembly for the visual display of the origin or direction of sounds; a stationary general purpose noise alarm; and a noise seeker wand.

  4. Directionally solidified eutectic ceramic oxides

    Microsoft Academic Search

    Javier LLorca; Victor M. Orera

    2006-01-01

    The processing, structure and properties (mechanical and functional) of directionally solidified eutectic ceramic oxides are reviewed with particular attention to the developments in the last 15 years. The article analyzes in detail the control of the microstructure from the processing variables, the recently gained knowledge on their microstructure (crystallographic orientation, interface structure, residual stresses, etc.), the microstructural and chemical stability

  5. Direct photon experiment at POLEX

    SciTech Connect

    Ohashi, Y.

    1989-01-01

    Significant contribution of the gluons to the proton spin has been suggested by several authors to explain the recent EMC results on the spin dependent structure function of proton. Direct photon measurements at large transverse momentum in pp reactions with pure initial helicity states is proposed in this paper in order to study spin dependent gluon structure function. 8 refs., 3 figs., 1 tab.

  6. Direction of First Aid Kit

    E-print Network

    Natelson, Douglas

    of the Laboratory Safety Plan. Note the locations of any exits and safety equipment present in the lab. Some examples would include: Fire/Life Safety Items Laboratory Safety Equipment Fire Extinguishers Eyewash station Direction of Exit Safety Shower Emergency Contact Information Fume hoods Fire alarm pull station

  7. Directions for Defense Digital Libraries.

    ERIC Educational Resources Information Center

    Larsen, Ronald L.

    1998-01-01

    Describes directions, challenges, and objectives of the information management program of the United States Defense Advanced Research Projects Agency (DARPA). The program envisions the rigor and organization normally associated with a research library to be virtually rendered and extended in the networked world of distributed information. (AEF)

  8. Reflections, Perceptions, and Future Directions.

    ERIC Educational Resources Information Center

    Renzulli, Joseph S.

    1999-01-01

    This response by the original author to critiques of his review of his own work in gifted education suggests possible new directions for the field. These include: the relationship between general and gifted education, the under representation of minority students as the "time bomb" of gifted education, achieving a balance between curricular…

  9. The Internet: Trends and Directions.

    ERIC Educational Resources Information Center

    Anderson, Byron

    1996-01-01

    Examines current trends and directions in information technology and telecommunications. Discusses legislation; mergers and acquisitions; Internet service providers; fiscal control in libraries and the pooling of electronic information access through consortiums; demand for more bandwidth; technology selection; Internet usage patterns; the…

  10. EMPLOYEE PAYROLL DIRECT DEPOSIT AUTHORIZATION

    E-print Network

    ) University ID Number NAME (LAST,FIRST,MIDDLE) TELEPHONE NUMBERS Home: ( ) Work: ( ) 2. ENTER BANKING INFORMATION (Please complete fully) BANK NAME BRANCH ADDRESS CITY STATE ZIPCODE ACTION (Check one) TYPE and my net pay amount each payday directly to my account at the financial institution specified. I agree

  11. Arrival Map and Unloading Directions

    E-print Network

    Royer, Dana

    Arrival Map and Unloading Directions Arrival Day Instructions If you live in Butterfield A or B at the Exley Science Center before unloading. If you live in Clark Hall, Butterfield C, 200 Church Street, Fauver, or 156 High Street, check in and unload at your residential area, park in one of the des- ignated

  12. Zeolite modification II - direct fluorination

    Microsoft Academic Search

    B. M. Lok; F. P. Gortsena; P. J. Izod; C. A. Messina; H. Rastelli

    1982-01-01

    Over the past thirty years, zeolite science has grown into a major branch of chemistry. A large number of new zeolite materials have been made by both direct hydrothermal synthesis and by post-synthesis modification. This has led to a large number of new applications in such diverse fields as catalysis, adsorption and ion exchange. In synthesis alone, over one hundred

  13. Direct from CDC Environmental Health

    E-print Network

    Direct from CDC Environmental Health Services Branch Pamela S. Wigington TeresaM.Sims Web for Disease Con trol and Prevention (CDC) in every issue of the Journal. EHSB's objective is to strengthen available for download on the Environmental Health Services Branch Web site (http://www. cdc

  14. Direct from CDC Environmental Health

    E-print Network

    Direct from CDC Environmental Health Services Branch CAPT John P. Sarisky, R.S., M for Disease Con trol and Prevention (CDC) in every issue of the Journal. In this column, EHSB and guest au thors from across CDC will highlight a variety of concerns, opportunities, chal lenges, and successes

  15. Direct from CDC Environmental Health

    E-print Network

    Direct from CDC Environmental Health Services Branch Healthy Housing Inspection Manual Now Available Editor's note: This month's column fea tures the preface from the newly released CDC/HUD Healthy Housing Inspection Manual. Request your CD-ROM copy of the manual by calling 1-800-CDC-INFO or sending

  16. Striation in Bridgman directional solidification

    Microsoft Academic Search

    R. Guérin; C Le Marec; P Haldenwang

    1998-01-01

    Time-dependent behaviours induced by the solutal convection appearing above a solidification front are numerically investigated. The system under study corresponds to the upward Bridgman configuration for the directional solidification of the Pb–30% Tl alloy. The purpose of this paper is to characterise the striations induced in the crystal when the flow becomes unsteady. We determine the onset threshold of unsteadiness

  17. Revisiting constraint-directed search

    Microsoft Academic Search

    Magnus Ågren; Pierre Flener; Justin Pearson

    2009-01-01

    We revisit the exploration of constraint-directed neighbour- hoods, where a (small) set of constraints is picked before considering the neighbouring configurations where those constraints have a decreased (or preserved, or increased) penalty. Given the semantics of a constraint, such neighbourhoods can be represented via new attributes or primi- tives for the corresponding constraint object. We show how to define these

  18. Directional Drilling and Earth Curvature

    Microsoft Academic Search

    H. S. Williamson; H. F. Wilson

    2000-01-01

    This paper provides a review of current practices for calculating directional drilling placement in the light of modern extended-reach applications. The review highlights the potential for gross errors in the application of geodetic reference information and errors inherent in the calculation method. Both types of error are quantified theoretically and illustrated with a real example. The authors borrow established land

  19. Geothermal direct contact heat exchange

    Microsoft Academic Search

    A. V. Sims

    1977-01-01

    A glass direct contact heat exchange column was operated in the laboratory. The column was operated at atmospheric pressure using hot water and normal hexane. Column internals testing included an empty column, sieve trays, disk-and-doughnut trays, and two types of packing. Operation was very smooth in all cases and the minimum temperature approaches varied from less than 1 C for

  20. Direct from CDC Environmental Health

    E-print Network

    Direct from CDC Environmental Health Services Branch HilaryHeishman,M.P.H. CAPTAndrew-date and relevant information on envi ronmental health and to build partnerships in the profession. In pursuit of these goals, we feature a column from the Environmen tal Health Services Branch (EHSB) of the Centers

  1. Direct from CDC Environmental Health

    E-print Network

    Direct from CDC Environmental Health Services Branch JeffreyS.Neistadt,M.S.,R.S. TimothyJ.Murphy,Ph.D.,R.E.H.S. Are We Really Saving Resources with Current Hiring Practices at Local Health Departments? Editor's note: NEHA strives to provide up-to-date and relevant information on environmental health and to build

  2. Direct from CDC Environmental Health

    E-print Network

    Direct from CDC Environmental Health Services Branch KateWright,M.P.H.,Ed.D. Environmental Public Health Leadership Development Editor's note: NEHA strives to provide up-to-date and relevant information on environmental health and to build part nerships in the profession. In pursuit of these goals, we feature

  3. Direct from CDC Environmental Health

    E-print Network

    Direct from CDC Environmental Health Services Branch Editor's note: NEHA strives to provide up-to-date and relevant information on environmental health and to build part nerships in the profession. In pursuit of these goals, we feature a column from the Environmental Health Services Branch (EHSB) of the Centers

  4. Dominating sets in directed graphs

    Microsoft Academic Search

    Chaoyi Pang; Rui Zhang; Qing Zhang; Junhu Wang

    2010-01-01

    We consider the problem of incrementally computing a minimal dominating set of a directed graph after the insertion or deletion of a set of arcs. Earlier results have either focused on the study of the properties that minimum (not minimal) dominating sets preserved or lacked to investigate which update affects a minimal dominating set and in what ways. In this

  5. Directional Dependence in Developmental Research

    ERIC Educational Resources Information Center

    von Eye, Alexander; DeShon, Richard P.

    2012-01-01

    In this article, we discuss and propose methods that may be of use to determine direction of dependence in non-normally distributed variables. First, it is shown that standard regression analysis is unable to distinguish between explanatory and response variables. Then, skewness and kurtosis are discussed as tools to assess deviation from…

  6. Exit Counseling Guide for Direct Loan Borrowers You borrowed Direct Subsidized Loans and/or

    E-print Network

    Amin, S. Massoud

    Exit Counseling Guide for Direct Loan Borrowers You borrowed Direct Subsidized Loans and/or Direct of Education. The word "loan" refers to one or more Direct Subsidized Loans or Direct Unsubsidized Loans Subsidized Loans) · Federal Direct Unsubsidized Stafford/Ford Loans (Direct Unsubsidized Loans) · Federal

  7. Direct detection of dark matter axions with directional sensitivity

    SciTech Connect

    Irastorza, Igor G.; García, Juan A., E-mail: Igor.Irastorza@cern.ch, E-mail: jagarpas@unizar.es [Laboratorio de Física Nuclear y Astropartículas, Departamento de Física Teórica, Universidad de Zaragoza, C/ Pedro Cerbuna 12, 50009, Zaragoza (Spain)

    2012-10-01

    We study the directional effect of the expected axion dark matter signal in a resonant cavity of an axion haloscope detector, for cavity geometries not satisfying the condition that the axion de Broglie wavelength ?{sub a} is sufficiently larger than the cavity dimensions L for a fully coherent conversion, i.e. ?{sub a}?>2?L. We focus on long thin cavities immersed in dipole magnets and find, for appropriately chosen cavity lengths, an O(1) modulation of the signal with the cavity orientation with respect the momentum distribution of the relic axion background predicted by the isothermal sphere model for the galactic dark matter halo. This effect can be exploited to design directional axion dark matter detectors, providing an unmistakable signature of the extraterrestrial origin of a possible positive detection. Moreover, the precise shape of the modulation may give information of the galactic halo distribution and, for specific halo models, give extra sensitivity for higher axion masses.

  8. Directed random walk on the directed percolation cluster Matthias Birkner

    E-print Network

    Mörters, Peter

    ) percolation space Zd time q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q p (0, 1 closed 3/21 #12;Directed percolation Directed (site) percolation space Zd time q q q q q q q q q q q q q

  9. Fault Branching and Rupture Directivity

    NASA Astrophysics Data System (ADS)

    Dmowska, R.; Rice, J. R.; Kame, N.

    2002-12-01

    Can the rupture directivity of past earthquakes be inferred from fault geometry? Nakata et al. [J. Geogr., 1998] propose to relate the observed surface branching of fault systems with directivity. Their work assumes that all branches are through acute angles in the direction of rupture propagation. However, in some observed cases rupture paths seem to branch through highly obtuse angles, as if to propagate ``backwards". Field examples of that are as follows: (1) Landers 1992. When crossing from the Johnson Valley to the Homestead Valley (HV) fault via the Kickapoo (Kp) fault, the rupture from Kp progressed not just forward onto the northern stretch of the HV fault, but also backwards, i.e., SSE along the HV [Sowers et al., 1994, Spotila and Sieh, 1995, Zachariasen and Sieh, 1995, Rockwell et al., 2000]. Measurements of surface slip along that backward branch, a prominent feature of 4 km length, show right-lateral slip, decreasing towards the SSE. (2) At a similar crossing from the HV to the Emerson (Em) fault, the rupture progressed backwards along different SSE splays of the Em fault [Zachariasen and Sieh, 1995]. (3). In crossing from the Em to Camp Rock (CR) fault, again, rupture went SSE on the CR fault. (4). Hector Mine 1999. The rupture originated on a buried fault without surface trace [Li et al., 2002; Hauksson et al., 2002] and progressed bilaterally south and north. In the south it met the Lavic Lake (LL) fault and progressed south on it, but also progressed backward, i.e. NNW, along the northern stretch of the LL fault. The angle between the buried fault and the northern LL fault is around -160o, and that NNW stretch extends around 15 km. The field examples with highly obtuse branch angles suggest that there may be no simple correlation between fault geometry and rupture directivity. We propose that an important distinction is whether those obtuse branches actually involved a rupture path which directly turned through the obtuse angle (while continuing also on the main fault), or rather involved arrest by a barrier on the original fault and jumping [Harris and Day, JGR, 1993] to a neighboring fault on which rupture propagated bilaterally to form what appears as a backward-branched structure. Our studies [Poliakov et al., JGR in press, 2002; Kame et al, EOS, 2002] of stress fields around a dynamically moving mode II crack tip show a clear tendency to branch from the straight path at high rupture speeds, but the stress fields never allow the rupture path to directly turn through highly obtuse angles, and hence that mechanism is unlikely. In contrast, study of fault maps in the vicinity of the Kp to HV fault transition [Sowers et al., 1994], discussed as case (1) above, strongly suggest that the large-angle branching occurred as a jump, which we propose as the likely general mechanism. Implications for the Nakata et al. [1998] aim of inferring rupture directivity from branch geometry is that this will be possible only when rather detailed characterization (by surface geology, seismic relocation, trapped waves) of fault connectivity can be carried out in the vicinity of the branching junction, to ascertain whether direct turning of the rupture path through an angle, or jumping and then propagating bilaterally, were involved in prior events. They have opposite implications for how we would associate past directivity with a (nominally) branched fault geometry.

  10. 28 CFR 36.208 - Direct threat.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...that individual poses a direct threat to the health or safety of others. (b) Direct threat means a significant...whether an individual poses a direct threat to the health or...must make an individualized assessment, based on reasonable...

  11. 24 CFR 9.131 - Direct threat.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...that individual poses a direct threat to the health or safety of others. (b) “Direct threat” means a significant...whether an individual poses a direct threat to the health or...make an individualized assessment, based on reasonable...

  12. Direction Counts: A Comparative Study of Spatially Directional Counting Biases in Cultures with Different Reading Directions

    ERIC Educational Resources Information Center

    Shaki, Samuel; Fischer, Martin H.; Gobel, Silke M.

    2012-01-01

    Western adults associate small numbers with left space and large numbers with right space. Where does this pervasive spatial-numerical association come from? In this study, we first recorded directional counting preferences in adults with different reading experiences (left to right, right to left, mixed, and illiterate) and observed a clear…

  13. Directed Evolution of Fungal Laccases

    PubMed Central

    Maté, Diana; García-Ruiz, Eva; Camarero, Susana; Alcalde, Miguel

    2011-01-01

    Fungal laccases are generalists biocatalysts with potential applications that range from bioremediation to novel green processes. Fuelled by molecular oxygen, these enzymes can act on dozens of molecules of different chemical nature, and with the help of redox mediators, their spectrum of oxidizable substrates is further pushed towards xenobiotic compounds (pesticides, industrial dyes, PAHs), biopolymers (lignin, starch, cellulose) and other complex molecules. In recent years, extraordinary efforts have been made to engineer fungal laccases by directed evolution and semi-rational approaches to improve their functional expression or stability. All these studies have taken advantage of Saccharomyces cerevisiae as a heterologous host, not only to secrete the enzyme but also, to emulate the introduction of genetic diversity through in vivo DNA recombination. Here, we discuss all these endeavours to convert fungal laccases into valuable biomolecular platforms on which new functions can be tailored by directed evolution. PMID:21966249

  14. Asymmetrically Coupled Directed Percolation Systems

    NASA Astrophysics Data System (ADS)

    Noh, Jae Dong; Park, Hyunggyu

    2005-04-01

    We introduce a dynamical model of coupled directed percolation systems with two particle species. The two species A and B are coupled asymmetrically in that A particles branch B particles, whereas B particles prey on A particles. This model may describe epidemic spreading controlled by reactive immunization agents. We study nonequilibrium phase transitions with attention focused on the multicritical point where both species undergo the absorbing phase transition simultaneously. In one dimension, we find that the inhibitory coupling from B to A is irrelevant and the model belongs to the unidirectionally coupled directed percolation class. On the contrary, a mean-field analysis predicts that the inhibitory coupling is relevant and a new universality appears with a variable dynamic exponent. Numerical simulations on small-world networks confirm our predictions.

  15. Visibility and directions in quasicrystals

    E-print Network

    Jens Marklof; Andreas Strömbergsson

    2014-08-08

    It is well known that a positive proportion of all points in a $d$-dimensional lattice is visible from the origin, and that these visible lattice points have constant density in $\\mathbb{R}^d$. In the present paper we prove an analogous result for a large class of quasicrystals, including the vertex set of a Penrose tiling. We furthermore establish that the statistical properties of the directions of visible points are described by certain $\\operatorname{SL}(d,\\mathbb{R})$-invariant point processes. Our results imply in particular existence and continuity of the gap distribution for directions in certain two-dimensional cut-and-project sets. This answers some of the questions raised by Baake et al. in [arXiv:1402.2818].

  16. Model transport directional solidification apparatus

    SciTech Connect

    Mason, J.T.; Eshelman, M.A.

    1986-07-01

    A model transport directional solidification apparatus is described. It has three functional components, each of which are described: the temperature gradient stage, the motor and drive mechanism, and the measuring systems. A small amount of sample is held between two glass slides on the temperature gradient stage so that the portion of sample in the hot chamber is molten and the portion in the cold chamber is solidified. Conditions are set so that the solid-liquid interface occurs in the gap between the chambers and can be observed through the microscope system. In-situ directional solidification is observed by driving the sample from the hot chamber to the cold chamber and observing the solidification process as it occurs. (LEW)

  17. Ultra-wideband directional sampler

    DOEpatents

    McEwan, T.E.

    1996-05-14

    The Ultra-Wideband (UWB) Directional Sampler is a four port device that combines the function of a directional coupler with a high speed sampler. Two of the four ports operate at a high sub-nanosecond speed, in ``real time``, and the other two ports operate at a slow millisecond-speed, in ``equivalent time``. A signal flowing inbound to either of the high speed ports is sampled and coupled, in equivalent time, to the adjacent equivalent time port while being isolated from the opposite equivalent time port. A primary application is for a time domain reflectometry (TDR) situation where the reflected pulse returns while the outbound pulse is still being transmitted, such as when the reflecting discontinuity is very close to the TDR apparatus. 3 figs.

  18. Direct Measurement of Rotational Relaxation

    Microsoft Academic Search

    M. L. Unland; W. H. FLYGAREt

    1966-01-01

    Several types of microwave double-resonance experiments are performed using a double-bridge superheterodyne detection scheme. The first set of experiments clarify some features of the double quantum effect and also confirm earlier experiments in a Stark-modulated spectrometer.The second set of experiments employs the double-bridge technique and the wide bandwidth capability of the 30-Mc\\/sec amplifiers to measure directly the restoration to equilibrium

  19. The Directed Planar Reachability Problem

    Microsoft Academic Search

    Eric Allender; Samir Datta; Sambuddha Roy

    2005-01-01

    We investigate thes-t-connectivity problem for directed planar graphs, which is hard for L and is contained in NL but is not known to be complete. We show that this problem is logspace-reducible to its complement, and we show that the problem of searching graphs of genus 1 reduces to the planar case. We also consider a previously-studied subclass of planar

  20. Direct generation of optical vortices

    NASA Astrophysics Data System (ADS)

    Williams, Mathew D.; Coles, Matt M.; Bradshaw, David S.; Andrews, David L.

    2014-03-01

    A detailed scheme is established for the direct generation of optical vortices, signifying light endowed with orbital angular momentum. In contrast to common techniques based on the tailored conversion of the wave front in a conventional beam, this method provides for the direct spontaneous emission of photons with the requisite field structure. This form of optical emission results directly from the electronic relaxation of a delocalized exciton state that is supported by a ringlike array of three or more nanoscale chromophores. An analysis of the conditions leads to a general formulation revealing a requirement for the array structure to adhere to one of a restricted set of permissible symmetry groups. It is shown that the coupling between chromophores within each array leads to an energy level splitting of the exciton structure, thus providing for a specific linking of exciton phase and emission wavelength. For emission, arrays conforming to one of the given point-group families' doubly degenerate excitons exhibit the specific phase characteristics necessary to support vortex emission. The highest order of exciton symmetry, corresponding to the maximum magnitude of electronic orbital angular momentum supported by the ring, provides for the most favored emission. The phase properties of the emission produced by the relaxation of such excitons are exhibited on plots which reveal the azimuthal phase progression around the ring, consistent with vortex emission. It is proven that emission of this kind produces electromagnetic fields that map with complete fidelity onto the phase structure of a Laguerre-Gaussian optical mode with the corresponding topological charge. The prospect of direct generation paves the way for practicable devices that need no longer rely on the modification of a conventional laser beam by a secondary optical element. Moreover, these principles hold promise for the development of a vortex laser, also based on nanoscale exciton decay, enabling the production of coherent radiation with a tailor-made helical wave front.

  1. Relativistic propulsion using directed energy

    NASA Astrophysics Data System (ADS)

    Bible, Johanna; Johansson, Isabella; Hughes, Gary B.; Lubin, Philip M.

    2013-09-01

    We propose a directed energy orbital planetary defense system capable of heating the surface of potentially hazardous objects to the evaporation point as a futuristic but feasible approach to impact risk mitigation. The system is based on recent advances in high efficiency photonic systems. The system could also be used for propulsion of kinetic or nuclear tipped asteroid interceptors or other interplanetary spacecraft. A photon drive is possible using direct photon pressure on a spacecraft similar to a solar sail. Given a laser power of 70GW, a 100 kg craft can be propelled to 1AU in approximately 3 days achieving a speed of 0.4% the speed of light, and a 10,000 kg craft in approximately 30 days. We call the system DE-STAR for Directed Energy System for Targeting of Asteroids and exploRation. DE-STAR is a modular phased array of solid-state lasers, powered by photovoltaic conversion of sunlight. The system is scalable and completely modular so that sub elements can be built and tested as the technology matures. The sub elements can be immediately utilized for testing as well as other applications including space debris mitigation. The ultimate objective of DE-STAR would be to begin direct asteroid vaporization and orbital modification starting at distances beyond 1 AU. Using phased array technology to focus the beam, the surface spot temperature on the asteroid can be raised to more than 3000K, allowing evaporation of all known substances. Additional scientific uses of DE-STAR are also possible.

  2. Death, Taxes and Advance Directives

    PubMed Central

    D’Amore, J.D.; Jones, S.L.; Sittig, D.F.; Ness, R.B.

    2014-01-01

    Summary Suboptimal care at the end-of-life can be due to lack of access or knowledge of patient wishes. Ambiguity is often the result of non-standardized formats. Borrowing digital technology from other industries and using existing health information infrastructure can greatly improve the completion, storage, and distribution of advance directives. We believe several simple, low-cost adaptations to regional and federal programs can raise the standard of end-of-life care. PMID:25024771

  3. Direct Detection with Dark Mediators

    E-print Network

    David Curtin; Ze'ev Surujon; Yuhsin Tsai

    2014-11-11

    We introduce dark mediator Dark matter (dmDM) where the dark and visible sectors are connected by at least one light mediator $\\phi$ carrying the same dark charge that stabilizes DM. $\\phi$ is coupled to the Standard Model via an operator $\\bar q q \\phi \\phi^*/\\Lambda$, and to dark matter via a Yukawa coupling $y_\\chi \\overline{\\chi^c}\\chi \\phi$. Direct detection is realized as the $2\\rightarrow3$ process $\\chi N \\rightarrow \\bar \\chi N \\phi$ at tree-level for $m_\\phi \\lesssim 10 \\ \\mathrm{keV}$ and small Yukawa coupling, or alternatively as a loop-induced $2\\rightarrow2$ process $\\chi N \\rightarrow \\chi N$. We explore the direct-detection consequences of this scenario and find that a heavy $\\mathcal{O}(100 \\ \\mathrm{GeV})$ dmDM candidate fakes different $\\mathcal{O}(10 \\ \\mathrm{GeV})$ standard WIMPs in different experiments. Large portions of the dmDM parameter space are detectable above the irreducible neutrino background and not yet excluded by any bounds. Interestingly, for the $m_\\phi$ range leading to novel direct detection phenomenology, dmDM is also a form of Self-Interacting Dark Matter (SIDM), which resolves inconsistencies between dwarf galaxy observations and numerical simulations.

  4. Directional Darwinian Selection in proteins

    PubMed Central

    2013-01-01

    Background Molecular evolution is a very active field of research, with several complementary approaches, including dN/dS, HON90, MM01, and others. Each has documented strengths and weaknesses, and no one approach provides a clear picture of how natural selection works at the molecular level. The purpose of this work is to present a simple new method that uses quantitative amino acid properties to identify and characterize directional selection in proteins. Methods Inferred amino acid replacements are viewed through the prism of a single physicochemical property to determine the amount and direction of change caused by each replacement. This allows the calculation of the probability that the mean change in the single property associated with the amino acid replacements is equal to zero (H0: ? = 0; i.e., no net change) using a simple two-tailed t-test. Results Example data from calanoid and cyclopoid copepod cytochrome oxidase subunit I sequence pairs are presented to demonstrate how directional selection may be linked to major shifts in adaptive zones, and that convergent evolution at the whole organism level may be the result of convergent protein adaptations. Conclusions Rather than replace previous methods, this new method further complements existing methods to provide a holistic glimpse of how natural selection shapes protein structure and function over evolutionary time. PMID:24267049

  5. Wellbore inertial directional surveying system

    DOEpatents

    Andreas, Ronald D. (Albuquerque, NM); Heck, G. Michael (Albuquerque, NM); Kohler, Stewart M. (Albuquerque, NM); Watts, Alfred C. (Albuquerque, NM)

    1991-01-01

    A wellbore inertial directional surveying system for providing a complete directional survey of an oil or gas well borehole to determine the displacement in all three directions of the borehole path relative to the well head at the surface. The information generated by the present invention is especially useful when numerous wells are drilled to different geographical targets from a single off-shore platform. Accurate knowledge of the path of the borehole allows proper well spacing and provides assurance that target formations are reached. The tool is lowered down into a borehole on the electrical cable. A computer positioned on the surface communicates with the tool via the cable. The tool contains a sensor block which is supported on a single gimbal, the rotation axis of which is aligned with the cylinder axis of the tool and, correspondingly, the borehole. The gyroscope measurement of the sensor block rotation is used in a null-seeking servo loop which essentially prevents rotation of the sensor block aboutthe gimbal axis. Angular rates of the sensor block about axes which are perpendicular to the gimbal axis are measured by gyroscopes in a manner similar to a strapped-down arrangement. Three accelerometers provide acceleration information as the tool is lowered within the borehole. The uphole computer derives position information based upon acceleration information and anular rate information. Kalman estimation techniques are used to compensate for system errors.

  6. When tobacco targets direct democracy.

    PubMed

    Laposata, Elizabeth; Kennedy, Allison P; Glantz, Stanton A

    2014-06-01

    Tobacco control advocates began to use ballot initiatives to enact tobacco control measures in the late 1970s. In response, the tobacco industry worked for over two decades to change laws governing initiative and referendum processes to prevent passage of such measures. In 1981 the tobacco industry's political lobbying arm, the Tobacco Institute, created a front group that presented itself as a neutral initiative research clearinghouse to effect changes in state initiative and referenda laws. In 1990 the Tobacco Institute began creating an in-house team and worked with third-party groups to try to change state initiative laws. While the industry ultimately abandoned both efforts when neither achieved immediate success, over time the industry's goals have penetrated legitimate discourse on the initiative and referendum process in the United States, and many specific ideas it advocated have garnered mainstream support. Direct democracy advocates, as well as public health advocates and policy makers, need to understand the tobacco industry's goals (which other industries adopted) of limiting the direct democracy process to ensure that any changes do not inadvertently increase the power of the special interests that direct democracy was developed to counterbalance. PMID:24603083

  7. Wellbore inertial directional surveying system

    DOEpatents

    Andreas, R.D.; Heck, G.M.; Kohler, S.M.; Watts, A.C.

    1982-09-08

    A wellbore inertial directional surveying system for providing a complete directional survey of an oil or gas well borehole to determine the displacement in all three directions of the borehole path relative to the well head at the surface. The information generated by the present invention is especially useful when numerous wells are drilled to different geographical targets from a single offshore platform. Accurate knowledge of the path of the borehole allows proper well spacing and provides assurance that target formations are reached. The tool is lowered down into a borehole on an electrical cable. A computer positioned on the surface communicates with the tool via the cable. The tool contains a sensor block which is supported on a single gimbal, the rotation axis of which is aligned with the cylinder axis of the tool and, correspondingly, the borehole. The gyroscope measurement of the sensor block rotation is used in a null-seeking servo loop which essentially prevents rotation of the sensor block about the gimbal axis. Angular rates of the sensor block about axes which are perpendicular to te gimbal axis are measured by gyroscopes in a manner similar to a strapped-down arrangement. Three accelerometers provide acceleration information as the tool is lowered within the borehole. The uphole computer derives position information based upon acceleration information and angular rate information. Kalman estimation techniques are used to compensate for system errors. 25 figures.

  8. Direct reciprocity in structured populations

    PubMed Central

    van Veelen, Matthijs; García, Julián; Rand, David G.; Nowak, Martin A.

    2012-01-01

    Reciprocity and repeated games have been at the center of attention when studying the evolution of human cooperation. Direct reciprocity is considered to be a powerful mechanism for the evolution of cooperation, and it is generally assumed that it can lead to high levels of cooperation. Here we explore an open-ended, infinite strategy space, where every strategy that can be encoded by a finite state automaton is a possible mutant. Surprisingly, we find that direct reciprocity alone does not lead to high levels of cooperation. Instead we observe perpetual oscillations between cooperation and defection, with defection being substantially more frequent than cooperation. The reason for this is that “indirect invasions” remove equilibrium strategies: every strategy has neutral mutants, which in turn can be invaded by other strategies. However, reciprocity is not the only way to promote cooperation. Another mechanism for the evolution of cooperation, which has received as much attention, is assortment because of population structure. Here we develop a theory that allows us to study the synergistic interaction between direct reciprocity and assortment. This framework is particularly well suited for understanding human interactions, which are typically repeated and occur in relatively fluid but not unstructured populations. We show that if repeated games are combined with only a small amount of assortment, then natural selection favors the behavior typically observed among humans: high levels of cooperation implemented using conditional strategies. PMID:22665767

  9. WHEN TOBACCO TARGETS DIRECT DEMOCRACY

    PubMed Central

    Laposata, Elizabeth; Kennedy, Allison P.

    2013-01-01

    Tobacco control advocates began to use ballot initiatives to enact tobacco control policies in the late 1970s. In response, the tobacco industry worked for over two decades to change laws governing initiative and referendum processes to prevent passage of tobacco control measures. In 1981, the tobacco industry’s political lobbying arm, the Tobacco Institute, created a front group that presented itself as a neutral initiative research clearinghouse to affect changes in state initiative and referenda laws. In 1990, the Tobacco Institute began creating an in-house team, and worked with third party groups to try to change state initiative laws. While the industry ultimately abandoned both efforts when neither achieved immediate success, over time, the industry’s goals have penetrated legitimate discourse on the I&R process in the United States and many specific ideas it advocated have garnered mainstream support. Direct democracy advocates, as well as public health advocates and policymakers, need to understand the tobacco industry’s goals (which other industries adopted) of limiting the direct democracy process in order to ensure that any changes do not inadvertently increase the power of the special interests that direct democracy was developed to counterbalance. PMID:24603083

  10. Plasticity in human directional hearing.

    PubMed

    Javer, A R; Schwarz, D W

    1995-04-01

    Interaural time difference (ITD), the main cue for localization of low-frequency sound in azimuth, is widely thought to be evaluated according to Jeffress' model. This theory proposes that each of an array of neurons detects coinciding input from both ears, conducted along axonal delay lines, with the azimuth angle corresponding to the activation of selected neurons. Thus, sound source localization is assumed to depend on axon conduction velocities, a relatively fixed parameter. Clinical experience suggests that directional hearing is adaptable. We investigated if sound localization in azimuth could adapt plastically to altered ITDs. We equipped binaural insert hearing aids with adjustable electronic delay lines. Subjects with normal hearing were required to wear these devices during all waking hours for several days. Localization of an invisible sound source was measured in an anechoic room before and at various intervals after introduction of a constant delay in one ear between 171 and 684 mus. Test sounds were high-pass, low-pass and broad-band noises. Introduction of a delay in one ear lead to an immediate displacement of the perceived sound location towards the opposite side. Within hours of exposure, the displacement was reduced, and further normalization of the perceived localization occurred over several days. After removal of the delays sound localization normalized rapidly. We conclude that ITD alterations can lead to plastic adaptation of directional hearing, which cannot rely exclusively on fixed axon conduction velocities. Our results suggest additional mechanisms for directional hearing on the basis ITD. PMID:7602671

  11. Do ants make direct comparisons?

    PubMed Central

    Robinson, Elva J.H.; Smith, Faith D.; Sullivan, Kathryn M.E.; Franks, Nigel R.

    2009-01-01

    Many individual decisions are informed by direct comparison of the alternatives. In collective decisions, however, only certain group members may have the opportunity to compare options. Emigrating ant colonies (Temnothorax albipennis) show sophisticated nest-site choice, selecting superior sites even when they are nine times further away than the alternative. How do they do this? We used radio-frequency identification-tagged ants to monitor individual behaviour. Here we show for the first time that switching between nests during the decision process can influence nest choice without requiring direct comparison of nests. Ants finding the poor nest were likely to switch and find the good nest, whereas ants finding the good nest were more likely to stay committed to that nest. When ants switched quickly between the two nests, colonies chose the good nest. Switching by ants that had the opportunity to compare nests had little effect on nest choice. We suggest a new mechanism of collective nest choice: individuals respond to nest quality by the decision either to commit or to seek alternatives. Previously proposed mechanisms, recruitment latency and nest comparison, can be explained as side effects of this simple rule. Colony-level comparison and choice can emerge, without direct comparison by individuals. PMID:19386652

  12. Wellbore inertial directional surveying system

    SciTech Connect

    Andreas, R.D.; Heck, G.M.; Kohler, S.M.; Watts, A.C.

    1991-01-29

    This patent describes a wellbore inertial directional surveying system for providing a complete directional survey of an oil or gas well borehole to determine the displacement in all three directions of the borehole path relative to the well head at the surface. The information generated by the present invention is especially useful when numerous wells are drilled to different geographical targets from a single off-shore platform. Accurate knowledge of the path of the borehole allows proper well spacing and provides assurance that target formations are reached. The tool is lowered down into a borehole on the electrical cable. A computer positioned on the surface communicates with the tool via the cable. The tool contains a sensor block which is supported on a single gimbal, the rotation axis of which is aligned with the cylinder axis of the tool and, correspondingly, the borehole. The gyroscope measurement of the sensor block rotation is used in a null-seeking servo loop which essentially prevents rotation of the sensor block about the gimbal axis. Angular rates of the sensor block about axes which are perpendicular to the gimbal axis are measured by gyroscopes in a manner similar to a strapped-down arrangement. Three accelerometers provide acceleration information as the tool is lowered within the borehole. The uphole computer derives position information based upon acceleration information and annular rate information. Kalman estimation techniques are used to compensate for system errors.

  13. Electrochimica Acta 52 (2007) 26492656 A simple method for the synthesis of PtRu nanoparticles on the

    E-print Network

    Zhao, Tianshou

    2007-01-01

    ) and chronoamperometry results demonstrated that the PtRu/MWCNT synthesized by this method exhibited a higher methanol oxidation current than did the PtRu/MWCNT synthesized by the more complex method using sodium borohydride (DMFC) performance test showed that the PtRu/MWCNT nanocatalyst used at the anode of the fuel cell

  14. Direct execution of LISP on a list-directed architecture

    SciTech Connect

    Sansonnet, J.P.; Castan, M.; Percebois, C.; Botella, D.; Perez, J.

    1982-03-01

    A direct-execution model dedicated to nonnumerical processing and based upon an internal representation of source programs derived from LISP has been defined. This model provides good support for sophisticated editing (syntactical parsing, tree manipulation, pretty-printing, ...) of conventional languages and artificial intelligence languages. A high level microprogramming language (LEM) was designed to write the interpreters and the editors. The influence of LISP on LEM and the architecture is discussed. The structure of the LISP is presented and evaluation measures dealing with size, development effort and speed are given. 30 references.

  15. Directional Lapped Transforms for Image Coding

    Microsoft Academic Search

    Jizheng Xu; Feng Wu; Jie Liang; Wenjun Zhang

    2010-01-01

    In this paper, we present the design of directional lapped transforms for image coding. A lapped transform, which can be implemented by a prefilter followed by a discrete cosine transform (DCT), can be factorized into elementary operators. The corresponding directional lapped transform is generated by applying each elementary operator along a given direction. The proposed directional lapped transforms are not

  16. A fingerprint classification technique using directional images

    Microsoft Academic Search

    Meltem Ballan; F. Ayhan Sakarya; Brian L. Evans

    1997-01-01

    We present a fast, automated, feature-based technique for classifying fingerprints. The technique extracts the singular points (delta and core points) in fingerprints obtained from directional histograms. The technique enhances the digitized image using adaptive clipping and image matching, finds the directional image by checking the orientations of individual pixels, computes directional histograms using overlapping blocks in the directional image, and

  17. Self-Directed Learning: Emerging Theory & Practice.

    ERIC Educational Resources Information Center

    Long, Huey B.; And Others

    This book contains the following collection of papers: "Self-Directed Learning: Emerging Theory and Practice" (Long); "Self-Directed Orientation toward Learning: A Learning Style" (Bonham); "Self-Direction and Problem Solving: Theory and Method" (Peters); "Facilitating Self-Directed Learning: Not a Contradiction in Terms" (Garrison); "Development…

  18. Evolving Sparse Direction Maps for Maze Pathfinding

    E-print Network

    Gordon, Scott

    a direction. The eight possible directions are in increments of 45 degrees. Figure 1 shows a 15x15 direction their actual maze location resides. Figure 1. 15x15 sparse direction map for a simple 24x24 maze Filling

  19. Direct (Anti-)Democracy Maxwell L. Stearns*

    E-print Network

    Hickman, Mark

    1 Direct (Anti-)Democracy Maxwell L. Stearns* Abstract Direct democracy debuted in the United of the process. In recent years, several states have relied upon direct democracy to press change on divisive expressed strong disagreement as to the wisdom and efficacy of direct democracy. The literature reveals

  20. GPU Computing with OpenACC Directives

    E-print Network

    Crawford, T. Daniel

    , with low-level access ! Compiler directives to specify parallel regions in C, C++, Fortran ! Open Languages OpenACC Directives Maximum Flexibility Easily Accelerate Applications #12;OpenACC Directives access to the massive parallel power of a GPU OpenACC The Standard for GPU Directives #12;High-level

  1. Improved directional drilling will expand use

    Microsoft Academic Search

    W. C. Maurer; W. J. McDonald; W. A. Rehm

    1979-01-01

    Directional drilling is important in present energy recovery technology and will become increasingly so in the future. Limitations of directional drilling and concepts for advanced systems both present and emerging energy technologies are detailed. To be technically and economically feasible methane drainage, in-situ retorting of oil shale, and underground gasification of coal will require directional drilling. Directional drilling is important

  2. Direct reaction effects on compound cross sections

    Microsoft Academic Search

    P. A. Moldauer

    1975-01-01

    Two effects of a direct reaction on compound processes are discussed: the enhancement of the average compound cross section that competes with the direct process and the cross correlations in the fluctuations of cross sections involving the directly coupled channels. For the case of two directly coupled channels it is shown that both effects are maximized at the causality limit

  3. Direct reaction effects on compound cross sections

    Microsoft Academic Search

    P. Moldauer

    1975-01-01

    Two effects of a direct reaction on compound processes are discussed: ; the enhancement of the average compound cross section that competes with the ; direct process and the cross correlations in the fluctuations of cross sections ; involving the directly coupled channels. For the case of two directly coupled ; channels it is shown that both effects are maximized

  4. Direct induction of cotton somatic embryogenesis

    Microsoft Academic Search

    Baohong Zhang; Rong Feng; Fang Liu; Changbing Yao

    1999-01-01

    COMPARED with indirect somatic embryogenesis, direct somatic embryogenesis appears to be associated with greater genetic and cytological uniformity, and it takes less time to induce direct embryogenesis than indirect embryogenesis. Although cotton somatic embryogenesis has been reported by many scientists, direct somatic embryogenesis has not been reported yetr'; . This letter first describes the induction of direct somatic embryogenesis and

  5. dmdd: Dark matter direct detection

    NASA Astrophysics Data System (ADS)

    Gluscevic, Vera; McDermott, Samuel D.

    2015-06-01

    The dmdd package enables simple simulation and Bayesian posterior analysis of recoil-event data from dark-matter direct-detection experiments under a wide variety of scattering theories. It enables calculation of the nuclear-recoil rates for a wide range of non-relativistic and relativistic scattering operators, including non-standard momentum-, velocity-, and spin-dependent rates. It also accounts for the correct nuclear response functions for each scattering operator and takes into account the natural abundances of isotopes for a variety of experimental target elements.

  6. Future directions in aeropropulsion technology

    NASA Technical Reports Server (NTRS)

    Saunders, N. T.; Glassman, A. J.

    1985-01-01

    Future directions in aeropropulsion technology that have been identified in a series of studies recently sponsored by the U.S. Government are discussed. Advanced vehicle concepts that could become possible by the turn of the century are presented along with some of their projected capabilities. Key building-block propulsion technologies that will contribute to making these vehicle concepts a reality are discussed along with projections of their status by the year 2000. Some pertinent highlights of the NASA aeropropulsion program are included in the discussion.

  7. Vitreous substitutes: challenges and directions

    PubMed Central

    Gao, Qian-Ying; Fu, Yue; Hui, Yan-Nian

    2015-01-01

    The natural vitreous body has a fine structure and complex functions. The imitation of the natural vitreous body by vitreous substitutes is a challenging work for both researchers and ophthalmologists. Gases, silicone oil, heavy silicone oil and hydrogels, particularly the former two vitreous substitutes are clinically widely used with certain complications. Those, however, are not real artificial vitreous due to lack of structure and function like the natural vitreous body. This article reviews the situations, challenges, and future directions in the development of vitreous substitutes, particularly the experimental and clinical use of a new artificial foldable capsular vitreous body. PMID:26085987

  8. Fatness and fertility: which direction?

    PubMed Central

    Seminara, Stephanie B.

    2014-01-01

    Metabolic status has long been thought to determine reproductive status, with abnormal metabolic phenotypes altering reproductive cascades, such as the onset of puberty. In this issue of the JCI, Tolson and colleagues provide evidence that kisspeptin, a hormone that promotes sexual maturation, regulates metabolism. Female mice lacking the kisspeptin receptor (KISS1R) gained more weight than control animals, and this weight gain was caused not by increased food consumption, but by an overall decrease in energy and metabolism. While this study provides a direct link between the kisspeptin pathway and metabolic output, more work will need to be done to determine whether alterations in this pathway contribute to human obesity. PMID:24937420

  9. Mesenchymal stromal cells: new directions.

    PubMed

    Keating, Armand

    2012-06-14

    Research into mesenchymal stromal/stem cells (MSCs) has been particularly exciting in the past five years. Our understanding of mechanisms of MSC-mediated tissue regeneration has undergone considerable evolution. Recent investigation of the primary in situ counterpart of cultured MSCs has led to fresh insights into MSC physiology and its role in the immune system. At the same time, the clinical application of MSCs continues to increase markedly. Taken together, a reappraisal of the definition of MSCs, a review of current research directions, and a reassessment of the approach to clinical investigation are timely and prudent. PMID:22704511

  10. Direct Arthroscopic Distal Clavicle Resection

    PubMed Central

    Lervick, Gregory N

    2005-01-01

    Degenerative change involving the acromioclavicular (AC) is frequently seen as part of a normal aging process. Occasionally, this results in a painful clinical condition. Although AC joint symptoms commonly occur in conjunction with other shoulder pathology, they may occur in isolation. Treatment of isolated AC joint osteoarthritis is initially non-surgical. When such treatment fails to provide lasting relief, surgical treatment is warranted. Direct (superior) arthroscopic resection of the distal (lateral) end of the clavicle is a successful method of treating the condition, as well as other isolated conditions of the AC joint. The following article reviews appropriate patient evaluation, surgical indications and technique. PMID:16089089

  11. Nerve lesioning with direct current

    NASA Astrophysics Data System (ADS)

    Ravid, E. Natalie; Shi Gan, Liu; Todd, Kathryn; Prochazka, Arthur

    2011-02-01

    Spastic hypertonus (muscle over-activity due to exaggerated stretch reflexes) often develops in people with stroke, cerebral palsy, multiple sclerosis and spinal cord injury. Lesioning of nerves, e.g. with phenol or botulinum toxin is widely performed to reduce spastic hypertonus. We have explored the use of direct electrical current (DC) to lesion peripheral nerves. In a series of animal experiments, DC reduced muscle force by controlled amounts and the reduction could last several months. We conclude that in some cases controlled DC lesioning may provide an effective alternative to the less controllable molecular treatments available today.

  12. Direct Reactions of Borromean Nuclei

    SciTech Connect

    Shimoura, S. [Center for Nuclear Study (CNS), University of Tokyo, Wako branch at RIKEN, Wako, Saitama 351-0198 (Japan)

    2008-04-29

    There are so-called Borromean nuclei on the drip-line in the nuclear chart, where any two-body subsystem has no bound state. The exotic structure and responses of Borromean nuclei have been studied by measurements of three-body (final-state) channels produced via direct reactions. Measurement of the three-body decay of the isospin partner of light drip-line nuclei populated by the charge exchange reaction is discussed as a means for studying the neutron halo structure. Experimental efforts to study nuclei beyond the drip-line, where many-body resonances may appear, are also presented.

  13. UROLOGIC ROBOTS AND FUTURE DIRECTIONS

    PubMed Central

    Mozer, Pierre; Troccaz, Jocelyne; Stoianovici, Dan

    2009-01-01

    Purpose of review Robot-assisted laparoscopic surgery in urology has gained immense popularity with the Da Vinci system but a lot of research teams are working on new robots. The purpose of this paper is to review current urologic robots and present future developments directions. Recent findings Future systems are expected to advance in two directions: improvements of remote manipulation robots and developments of image-guided robots. Summary The final goal of robots is to allow safer and more homogeneous outcomes with less variability of surgeon performance, as well as new tools to perform tasks based on medical transcutaneous imaging, in a less invasive way, at lower costs. It is expected that improvements for remote system could be augmented reality, haptic feed back, size reduction and development of new tools for NOTES surgery. The paradigm of image-guided robots is close to a clinical availability and the most advanced robots are presented with end-user technical assessments. It is also notable that the potential of robots lies much further ahead than the accomplishments of the daVinci system. The integration of imaging with robotics holds a substantial promise, because this can accomplish tasks otherwise impossible. Image guided robots have the potential to offer a paradigm shift. PMID:19057227

  14. Urologic robots and future directions

    E-print Network

    Mozer, Pierre; Stoianovici, Dan; 10.1097/MOU.0b013e32831cc1ba

    2008-01-01

    PURPOSE OF REVIEW: Robot-assisted laparoscopic surgery in urology has gained immense popularity with the daVinci system, but a lot of research teams are working on new robots. The purpose of this study is to review current urologic robots and present future development directions. RECENT FINDINGS: Future systems are expected to advance in two directions: improvements of remote manipulation robots and developments of image-guided robots. SUMMARY: The final goal of robots is to allow safer and more homogeneous outcomes with less variability of surgeon performance, as well as new tools to perform tasks on the basis of medical transcutaneous imaging, in a less invasive way, at lower costs. It is expected that improvements for a remote system could be augmented in reality, with haptic feedback, size reduction, and development of new tools for natural orifice translumenal endoscopic surgery. The paradigm of image-guided robots is close to clinical availability and the most advanced robots are presented with end-use...

  15. Model Independent Direct Detection Analyses

    E-print Network

    A. Liam Fitzpatrick; Wick Haxton; Emanuel Katz; Nicholas Lubbers; Yiming Xu

    2012-11-12

    Following the construction of the general effective theory for dark matter direct detection in 1203.3542, we perform an analysis of the experimental constraints on the full parameter space of elastically scattering dark matter. We review the prescription for calculating event rates in the general effective theory and discuss the sensitivity of various experiments to additional nuclear responses beyond the spin-independent (SI) and spin-dependent (SD) couplings: an angular-momentum-dependent (LD) and spin-and-angular-momentum-dependent (LSD) response, as well as a distinction between transverse and longitudinal spin-dependent responses. We consider the effect of interference between different operators and in particular look at directions in parameter space where such cancellations lead to holes in the sensitivity of individual experiments. We explore the complementarity of different experiments by looking at the improvement of bounds when experiments are combined. Finally, our scan through parameter space shows that within the assumptions on models and on the experiments' sensitivity that we make, no elastically scattering dark matter explanation of DAMA is consistent with all other experiments at 90%, though we find points in parameter space that are ruled out only by about a factor of 2 in the cross-section.

  16. Boltzmann, Darwin and Directionality theory

    NASA Astrophysics Data System (ADS)

    Demetrius, Lloyd A.

    2013-09-01

    Boltzmann’s statistical thermodynamics is a mathematical theory which relates the macroscopic properties of aggregates of interacting molecules with the laws of their interaction. The theory is based on the concept thermodynamic entropy, a statistical measure of the extent to which energy is spread throughout macroscopic matter. Macroscopic evolution of material aggregates is quantitatively explained in terms of the principle: Thermodynamic entropy increases as the composition of the aggregate changes under molecular collision. Darwin’s theory of evolution is a qualitative theory of the origin of species and the adaptation of populations to their environment. A central concept in the theory is fitness, a qualitative measure of the capacity of an organism to contribute to the ancestry of future generations. Macroscopic evolution of populations of living organisms can be qualitatively explained in terms of a neo-Darwinian principle: Fitness increases as the composition of the population changes under variation and natural selection. Directionality theory is a quantitative model of the Darwinian argument of evolution by variation and selection. This mathematical theory is based on the concept evolutionary entropy, a statistical measure which describes the rate at which an organism appropriates energy from the environment and reinvests this energy into survivorship and reproduction. According to directionality theory, microevolutionary dynamics, that is evolution by mutation and natural selection, can be quantitatively explained in terms of a directionality principle: Evolutionary entropy increases when the resources are diverse and of constant abundance; but decreases when the resource is singular and of variable abundance. This report reviews the analytical and empirical support for directionality theory, and invokes the microevolutionary dynamics of variation and selection to delineate the principles which govern macroevolutionary dynamics of speciation and extinction. We also elucidate the relation between thermodynamic entropy, which pertains to the extent of energy spreading and sharing within inanimate matter, and evolutionary entropy, which refers to the rate of energy appropriation from the environment and allocation within living systems. We show that the entropic principle of thermodynamics is the limit as R?0, M??, (where R denote the resource production rate, and M denote population size) of the entropic principle of evolution. We exploit this relation between the thermodynamic and evolutionary tenets to propose a physico-chemical model of the transition from inanimate matter which is under thermodynamic selection, to living systems which are subject to evolutionary selection. Life history variation and the evolution of senescence The evolutionary dynamics of speciation and extinction Evolutionary trends in body size. The origin of sporadic forms of cancer and neurological diseases, and the evolution of cooperation are important recent applications of directionality theory. These applications, which draw from the medical sciences and sociobiology, appeal to methods which lie outside the formalism described in this report. A companion review, Demetrius and Gundlach (submitted for publication), gives an account of these applications.An important aspect of this report pertains to the connection between statistical mechanics and evolutionary theory and its implications towards understanding the processes which underlie the emergence of living systems from inanimate matter-a problem which has recently attracted considerable attention, Morowitz (1992), Eigen (1992), Dyson (2000), Pross (2012).The connection between the two disciplines can be addressed by appealing to certain extremal principles which are considered the mainstay of the respective theories.The extremal principle in statistical mechanics can be stated as follows:

  17. Multi-directional local search

    PubMed Central

    Tricoire, Fabien

    2012-01-01

    This paper introduces multi-directional local search, a metaheuristic for multi-objective optimization. We first motivate the method and present an algorithmic framework for it. We then apply it to several known multi-objective problems such as the multi-objective multi-dimensional knapsack problem, the bi-objective set packing problem and the bi-objective orienteering problem. Experimental results show that our method systematically provides solution sets of comparable quality with state-of-the-art methods applied to benchmark instances of these problems, within reasonable CPU effort. We conclude that the proposed algorithmic framework is a viable option when solving multi-objective optimization problems. PMID:25140071

  18. Identifying Contienents, Oceans, and Directions

    NSDL National Science Digital Library

    Ms.Bingham

    2007-11-06

    Utah Core Curriculum Social Studies Standard #6: Students use map skills to analyze the influence of physical features of th building of communities in the United States. Objective #1: Examine Maps and Globes Indicator #1: Identify Oceans and Continents of the World. Using the following activities and instructions you will be able to learn about the 5 oceans and the 7 continents. You will also be able to find them on a map get better understanding of the four directions. As we discussed last time in class the five oceans of the world are: Artic Ocean Atlantic Ocean Pacific Ocean Indian Ocean Southern Ocean (discovered in 2000) Click on the link below and print out the worksheet. This will help you locate the oceans and recognize their placement. Complete the worksheet to the best of our ...

  19. Direct synthesis of calcium borohydride

    DOEpatents

    Ronnebro, Ewa Carin Ellinor (Dublin, CA); Majzoub, Eric H. (Pleasanton, CA)

    2009-10-27

    A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Ca(BH.sub.4).sub.2, from the alkaline earth metal hydride and the alkaline earth metal boride. The borohydride thus prepared is doped with a small portion of a metal chloride catalyst compound, such as RuCl.sub.3, TiCl.sub.3, or a mixture of TiCl.sub.3 and palladium metal. The process provides for mechanically mixing the dry reagents under an inert atmosphere followed by charging the mixed materials with high pressure hydrogen at about 70 MPa while heating the mixture to about 400.degree. C. The method is relatively simple and inexpensive and provides reversible hydride compounds which are free of the usual contamination introduced by prior art wet chemical methods.

  20. High gradient directional solidification furnace

    NASA Technical Reports Server (NTRS)

    Aldrich, B. R.; Whitt, W. D. (inventor)

    1985-01-01

    A high gradient directional solidification furnace is disclosed which includes eight thermal zones throughout the length of the furnace. In the hot end of the furnace, furnace elements provide desired temperatures. These elements include Nichrome wire received in a grooved tube which is encapsulated y an outer alumina core. A booster heater is provided in the hot end of the furnace which includes toroidal tungsten/rhenium wire which has a capacity to put heat quickly into the furnace. An adiabatic zone is provided by an insulation barrier to separate the hot end of the furnace from the cold end. The old end of the furnace is defined by additional heating elements. A heat transfer plate provides a means by which heat may be extracted from the furnace and conducted away through liquid cooled jackets. By varying the input of heat via the booster heater and output of heat via the heat transfer plate, a desired thermal gradient profile may be provided.

  1. Directional Properties of Infragravity Waves

    NASA Astrophysics Data System (ADS)

    Sheremet, A.; Guza, R. T.; Elgar, S.; Herbers, T. H.

    2002-12-01

    The directional properties of infragravity waves are studied using field observations obtained across the shoaling and surf zones of a gently sloping sandy beach. Five alongshore arrays, each containing collocated p, u and v sensors (pressure, cross-shore and alongshore velocity respectively), were deployed in between 1- and 6-m water depth for four months. A new estimator technique is described that uses observed cross- and auto-spectra between p, u and v sensors in each alongshore array to estimate infragravity energy fluxes in alongshore wavenumber - frequency (f-ky) space. The analysis sometimes shows significant shoreward energy flux at the f-ky corresponding to (theoretically) refractively trapped modes, suggesting that a significant fraction of this energy can be dissipated in the surf zone. This research was supported by the Office of Naval Research and the National Ocean Partnership Program.

  2. Directional solidification with heat losses

    NASA Technical Reports Server (NTRS)

    Brattkus, K.; Davis, S. H.

    1988-01-01

    The upward directional solidification of a dilute binary alloy in a tall, thin, two-dimensional slot is considered. Heat losses from the sidewalls produce curved isotherms, interface deformations, and melt convection. An asymptotic approach is used which relates the small heat loss to the thinness of the solidification cell, and solutions are obtained for the resulting melt convection, interface deflection, and the distribution of heat and solute. The model is compared to the numerical results of Chang and Brown (1983) which exclude the effects of solute buoyancy and thermodynamic equilibrium at the interface. The radial segregation at the interface (consistent with both interface shapes and temperature fields) is computed, and it is found that the radial segregation is independent of interfacial shapes; the radial segregation cannot be calculated from only a knowledge of the interface shape.

  3. Theory of directional pulse propagation

    SciTech Connect

    Kinsler, P.; Radnor, S. B. P.; New, G. H. C. [Department of Physics, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)

    2005-12-15

    We construct combined electric and magnetic field variables which independently represent energy flows in the forward and backward directions, respectively, and use these to reformulate Maxwell's equations. These variables enable us to not only judge the effect and significance of backward-traveling field components, but also to discard them when appropriate. They thereby have the potential to simplify numerical simulations, leading to potential speed gains of up to 100% over standard finite difference time-domain (FDTD) or pseudospectral spatial-domain (PSSD) simulations. We present results for various illustrative situations, including an example application to second harmonic generation in periodically poled lithium niobate. These field variables are also used to derive both envelope equations useful for narrow-band pulse propagation, and a second order wave equation. Alternative definitions are also presented.

  4. New directions in hospital governance.

    PubMed

    Shortell, S M

    1989-01-01

    This article suggests new directions for hospital governance to meet the demands of a rapidly changing health care environment. Board members must increasingly play roles as risk takers, strategic directors, experts, mentors, and evaluators. Lessons from other industries regarding risk taking, use of expertise, and streamlining decision making must be adapted to meet hospital needs. Recent data suggest that these needs may still differ by hospital ownership despite a convergence in investor-owned and not-for-profit corporate structures. The effectiveness of hospital boards in the future will depend on their ability to: (1) manage a diverse group of stakeholders; (2) involve physicians in the management and governance process; (3) meet the governance needs of multi-institutional systems and hospital restructuring; (4) meet the challenges of diversification and vertical integration; and (5) understand strategy formulation and implementation as interdependent and interrelated processes. PMID:10303235

  5. Multi-directional local search.

    PubMed

    Tricoire, Fabien

    2012-12-01

    This paper introduces multi-directional local search, a metaheuristic for multi-objective optimization. We first motivate the method and present an algorithmic framework for it. We then apply it to several known multi-objective problems such as the multi-objective multi-dimensional knapsack problem, the bi-objective set packing problem and the bi-objective orienteering problem. Experimental results show that our method systematically provides solution sets of comparable quality with state-of-the-art methods applied to benchmark instances of these problems, within reasonable CPU effort. We conclude that the proposed algorithmic framework is a viable option when solving multi-objective optimization problems. PMID:25140071

  6. Directed forgetting and directed remembering in visual working memory.

    PubMed

    Williams, Melonie; Woodman, Geoffrey F

    2012-09-01

    A defining characteristic of visual working memory is its limited capacity. This means that it is crucial to maintain only the most relevant information in visual working memory. However, empirical research is mixed as to whether it is possible to selectively maintain a subset of the information previously encoded into visual working memory. Here we examined the ability of participants to use cues to either forget or remember a subset of the information already stored in visual working memory. In Experiment 1, participants were cued to either forget or remember 1 of 2 groups of colored squares during a change-detection task. We found that both types of cues aided performance in the visual working memory task but that observers benefited more from a cue to remember than a cue to forget a subset of the objects. In Experiment 2, we show that the previous findings, which indicated that directed-forgetting cues are ineffective, were likely due to the presence of invalid cues that appeared to cause observers to disregard such cues as unreliable. In Experiment 3, we recorded event-related potentials and show that an electrophysiological index of focused maintenance is elicited by cues that indicate which subset of information in visual working memory needs to be remembered, ruling out alternative explanations of the behavioral effects of retention-interval cues. The present findings demonstrate that observers can focus maintenance mechanisms on specific objects in visual working memory based on cues indicating future task relevance. PMID:22409182

  7. Directed Forgetting and Directed Remembering in Visual Working Memory

    PubMed Central

    Williams, Melonie; Woodman, Geoffrey F.

    2013-01-01

    A defining characteristic of visual working memory is its limited capacity. This means that it is crucial to maintain only the most relevant information in visual working memory. However, empirical research is mixed as to whether it is possible to selectively maintain a subset of the information previously encoded into visual working memory. Here we examined the ability of subjects to use cues to either forget or remember a subset of the information already stored in visual working memory. In Experiment 1, participants were cued to either forget or remember one of two groups of colored squares during a change-detection task. We found that both types of cues aided performance in the visual working memory task, but that observers benefited more from a cue to remember than a cue to forget a subset of the objects. In Experiment 2, we show that the previous findings, which indicated that directed-forgetting cues are ineffective, were likely due to the presence of invalid cues that appear to cause observers to disregard such cues as unreliable. In Experiment 3, we recorded event-related potentials (ERPs) and show that an electrophysiological index of focused maintenance is elicited by cues that indicate which subset of information in visual working memory needs to be remembered, ruling out alternative explanations of the behavioral effects of retention-interval cues. The present findings demonstrate that observers can focus maintenance mechanisms on specific objects in visual working memory based on cues indicating future task relevance. PMID:22409182

  8. Supporting self-directed learning Running head: SUPPORTING SELF-DIRECTED LEARNING

    E-print Network

    Fischer, Gerhard

    1 Supporting self-directed learning Running head: SUPPORTING SELF-DIRECTED LEARNING Supporting Self-Directed Boulder, Colorado USA gerhard@colorado.edu #12;2 Supporting self-directed learning Abstract Making and resources for self-directed learning to support learners of all ages to (1) engage in authentic

  9. Directive 2600-027 Page 1 Directive sur la scurit informatique

    E-print Network

    Spino, Claude

    Directive 2600-027 Page 1 Directive sur la sécurité informatique DIRECTIVE 2600-027 TITRE : Directive sur la sécurité informatique ADOPTION : Comité de direction Résolution : CD-2006-02-14-08 ENTRÉE ........................................... 4 8. Responsabilités de gestion en sécurité informatique

  10. Directional light coupling from microdisk lasers

    Microsoft Academic Search

    A. F. J. Levi; R. E. Slusher; S. L. McCall; J. L. Glass; S. J. Pearton; R. A. Logan

    1993-01-01

    We describe methods for directional coupling of light output from whispering-gallery mode microdisk lasers. Patterned asymmetries in the shape of microdisk resonators provide control of both direction and intensity of light output without dramatically increasing laser thresholds.

  11. Physical limits on cellular directional mechanosensing

    E-print Network

    Bouffanais, Roland

    Many eukaryotic cells are able to perform directional mechanosensing by directly measuring minute spatial differences in the mechanical stress on their membranes. Here, we explore the limits of a single mechanosensitive ...

  12. Outrunning Nature: Directed Evolution of Superior Biocatalysts

    ERIC Educational Resources Information Center

    Woodyer, Ryan; Chen, Wilfred; Zhao, Huimin

    2004-01-01

    The development of enzymes as biocatalysts for industrial use and the emergence of directed evolution in the invention of advanced biocatalysts are discussed and illustrated. Thus, directed evolution has bridged the functional gap between natural and specially designed biocatalysts.

  13. VOLATILE ORGANIC ANALYSIS BY DIRECT AQUEOUS INJECTION

    EPA Science Inventory

    Gas chromatographic environmental analysis by direct aqueous injection (DAI) was studied for 24 volatile organic analytes (VOAs). Internal standardization was used to determine the precision of analyzing these compounds by DAI. Aequous samples were directly introduced to a gas ch...

  14. 30 CFR 556.71 - Directional drilling.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Directional drilling. 556.71 Section 556.71 Mineral...Extensions § 556.71 Directional drilling. In accordance with an approved...by the lease. In such circumstances, drilling shall be considered to have...

  15. 30 CFR 556.71 - Directional drilling.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 2013-07-01 false Directional drilling. 556.71 Section 556.71 Mineral...Extensions § 556.71 Directional drilling. In accordance with an approved...by the lease. In such circumstances, drilling shall be considered to have...

  16. 30 CFR 556.71 - Directional drilling.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 2012-07-01 false Directional drilling. 556.71 Section 556.71 Mineral...Extensions § 556.71 Directional drilling. In accordance with an approved...by the lease. In such circumstances, drilling shall be considered to have...

  17. BROADCASTING ONNETWORKS OF SENSORS COMMUNICATING THROUGH DIRECTIONAL

    E-print Network

    Genève, Université de

    BROADCASTING ONNETWORKS OF SENSORS COMMUNICATING THROUGH DIRECTIONAL ANTENNAS #3; G. Arzhantseva graphs as the basis for a model for networks of sensors communicating through radio frequency using directional antennas. We propose two broadcasting algorithms, and compare empirically their performance

  18. 33 CFR 86.07 - Directional properties.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Directional properties. 86.07 Section 86.07 Navigation and Navigable Waters COAST GUARD, DEPARTMENT...Whistles § 86.07 Directional properties. The sound pressure...

  19. 33 CFR 86.07 - Directional properties.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Directional properties. 86.07 Section 86.07 Navigation and Navigable Waters COAST GUARD, DEPARTMENT...Whistles § 86.07 Directional properties. The sound pressure...

  20. 33 CFR 86.07 - Directional properties.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Directional properties. 86.07 Section 86.07 Navigation and Navigable Waters COAST GUARD, DEPARTMENT...Whistles § 86.07 Directional properties. The sound pressure...

  1. 33 CFR 86.07 - Directional properties.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Directional properties. 86.07 Section 86.07 Navigation and Navigable Waters COAST GUARD, DEPARTMENT...Whistles § 86.07 Directional properties. The sound pressure...

  2. 33 CFR 86.07 - Directional properties.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Directional properties. 86.07 Section 86.07 Navigation and Navigable Waters COAST GUARD, DEPARTMENT...Whistles § 86.07 Directional properties. The sound pressure...

  3. 75 FR 15387 - Veterinary Feed Directive

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-29

    ...Docket No. FDA-2010-N-0155] Veterinary Feed Directive AGENCY: Food and Drug...to its current regulation relating to veterinary feed directive (VFD) drugs. FDA's...CONTACT: Neal Bataller, Center for Veterinary Medicine (HFV-230), Food and...

  4. Direct and Indirect Experience in Salar

    E-print Network

    Dwyer, Arienne M.

    2000-01-01

    Salar rigorously distinguishes direct from indirect experience: if experience is perceived as indirect, utterances must be so marked. The corelation of direct and indirect forms with personal deixis (Givón 1984) in ...

  5. 30 CFR 256.71 - Directional drilling.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Directional drilling. 256.71 Section...OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Assignments, Transfers...256.71 Directional drilling. In accordance...such circumstances, drilling shall be...

  6. 30 CFR 256.71 - Directional drilling.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Directional drilling. 256.71 Section...OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Assignments, Transfers...256.71 Directional drilling. In accordance...such circumstances, drilling shall be...

  7. Production of direct reduced iron using coal

    SciTech Connect

    Sanzenbacher, C.W.

    1982-10-01

    The use of direct reduced iron as feedstock is rapidly becoming more attractive as electric arc steelmaking continues to grow worldwide. Because of uncertainties in both price and availability of natural gas in the US, coal is being investigated as a stable energy source. Current technology is presented in this paper including coal gasification with direct reduction shaft furnaces, coke-oven gas in direct reduction, and the Midrex electrothermal direct reduction process which involves the use of coal and electrical energy.

  8. Direct shear testing of polished slickensided surfaces

    Microsoft Academic Search

    Christopher L. Meehan; Thomas L. Brandon; J. Michael Duncan; Binod Tiwari

    2010-01-01

    A series of ring shear and direct shear tests were performed to measure the drained residual strength of three clay soils.\\u000a For each of the soils, slickensided direct shear specimens were prepared by wire-cutting intact specimens, and polishing the\\u000a resulting shear plane on a variety of surfaces to align the clay particles in the direction of shear. Drained direct shear

  9. Directed Forgetting of Recently Recalled Autobiographical Memories

    ERIC Educational Resources Information Center

    Barnier, Amanda J.; Conway, Martin A.; Mayoh, Lyndel; Speyer, Joanne; Avizmil, Orit; Harris, Celia B.

    2007-01-01

    In 6 experiments, the authors investigated list-method directed forgetting of recently recalled autobiographical memories. Reliable directed forgetting effects were observed across all experiments. In 4 experiments, the authors examined the impact of memory valence on directed forgetting. The forget instruction impaired recall of negative,…

  10. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming (Los Alamos, NM)

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source.

  11. Determining Directional Dependency in Causal Associations

    ERIC Educational Resources Information Center

    Pornprasertmanit, Sunthud; Little, Todd D.

    2012-01-01

    Directional dependency is a method to determine the likely causal direction of effect between two variables. This article aims to critique and improve upon the use of directional dependency as a technique to infer causal associations. We comment on several issues raised by von Eye and DeShon (2012), including: encouraging the use of the signs of…

  12. Judge Authority in Directing Civil Action Proceedings

    E-print Network

    #12;#12;Abstract Judge Authority in Directing Civil Action Proceedings by Mohamad Ali Kalel Al in directing civil action proceedings. Research problem arises when considering the role played by a judge in directing civil action proceedings in scope of pleadings declaration, counter- pleadings, judge power

  13. Emerging Perspectives of Self-Directed Learning.

    ERIC Educational Resources Information Center

    Long, Huey B.; And Others

    These 17 papers attest to the deepening and broadening interest in self-directed learning as one solution to the lifelong learning needs of men and women in an increasingly dynamic society. The papers include the following: "Self-Directed Learning Knowledge: Some Issues" (Long); "Development of Self-Directed Learning Readiness: A Longitudinal…

  14. A direct control method for matrix converters

    Microsoft Academic Search

    Peter Mutschler; Matthias Marcks

    2002-01-01

    Until now, direct control methods have been mainly investigated and used in conjunction with voltage source converters. In this paper, the authors develop a direct current control method for matrix converters. There are two objectives for the direct current control: the desired current has to be impressed into the load, and the current, drawn from the mains, should be in

  15. Future Directions in Ultraviolet Spectroscopy

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Editor); Moos, Warren; VanSteenberg, Michael

    2009-01-01

    The 'Future Directions in Ultraviolet Spectroscopy' conference was inspired by the accomplishments of the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission. The FUSE mission was launched in June 1999 and spent over eight years exploring the far-ultraviolet universe, gathering over 64 million seconds of high-resolution spectral data on nearly 3000 astronomical targets. The goal of this conference was not only to celebrate the accomplishments of FUSE, but to look toward the future and understand the major scientific drivers for the ultraviolet capabilities of the next generation fo space observatories. Invited speakers presented discussions based on measurements made by FUSE and other ultraviolet instruments, assessed their connection with measurements made with other techniques and, where appropriate, discussed the implications of low-z measurements for high-z phenomena. In addition to the oral presentations, many participants presented poster papers. The breadth of these presentation made it clear that much good science is still in progress with FUSE data and that these result will continue to have relevance in many scientific areas.

  16. Efficiency of parallel direct optimization

    NASA Technical Reports Server (NTRS)

    Janies, D. A.; Wheeler, W. C.

    2001-01-01

    Tremendous progress has been made at the level of sequential computation in phylogenetics. However, little attention has been paid to parallel computation. Parallel computing is particularly suited to phylogenetics because of the many ways large computational problems can be broken into parts that can be analyzed concurrently. In this paper, we investigate the scaling factors and efficiency of random addition and tree refinement strategies using the direct optimization software, POY, on a small (10 slave processors) and a large (256 slave processors) cluster of networked PCs running LINUX. These algorithms were tested on several data sets composed of DNA and morphology ranging from 40 to 500 taxa. Various algorithms in POY show fundamentally different properties within and between clusters. All algorithms are efficient on the small cluster for the 40-taxon data set. On the large cluster, multibuilding exhibits excellent parallel efficiency, whereas parallel building is inefficient. These results are independent of data set size. Branch swapping in parallel shows excellent speed-up for 16 slave processors on the large cluster. However, there is no appreciable speed-up for branch swapping with the further addition of slave processors (>16). This result is independent of data set size. Ratcheting in parallel is efficient with the addition of up to 32 processors in the large cluster. This result is independent of data set size. c2001 The Willi Hennig Society.

  17. Direct Measurement of Turbulent Shear

    NASA Astrophysics Data System (ADS)

    Stefanus, Stefanus; Steers, Stanley; Goldburg, Walter

    2010-11-01

    Photon Correlation Spectroscopy (PCS) is used to directly measure the mean shear rate s in a turbulent soap film. A 5 mW 633 nm He-Ne laser is focused on the film at a point r, the spot size being w =100 ?m. The scattered light intensity I(t) is analyzed by a correlator that measures the average, over time t, of the correlation function G(?) = /

  18. Gravitational spectra from direct measurements

    NASA Technical Reports Server (NTRS)

    Wagner, C. A.; Colombo, O. L.

    1978-01-01

    A simple rapid method is described for determining the spectrum of a surface field from harmonic analysis of direct measurements along great circle arcs. The method is shown to give excellent overall trends to very high degree from even a few short arcs of satellite data. Three examples are taken with perfect measurements of satellite tracking over a planet made up of hundreds of point-masses using (1) altimetric heights from a low orbiting spacecraft, (2) velocity residuals between a low and a high satellite in circular orbits, and (3) range-rate data between a station at infinity and a satellite in highly eccentric orbit. In particular, the smoothed spectrum of the Earth's gravitational field is determined to about degree 400(50 km half wavelength) from 1 D x 1 D gravimetry and the equivalent of 11 revolutions of Geos 3 and Skylab altimetry. This measurement shows there is about 46 cm of geoid height remaining in the field beyond degree 180.

  19. Direct digital conversion detector technology

    NASA Astrophysics Data System (ADS)

    Mandl, William J.; Fedors, Richard

    1995-06-01

    Future imaging sensors for the aerospace and commercial video markets will depend on low cost, high speed analog-to-digital (A/D) conversion to efficiently process optical detector signals. Current A/D methods place a heavy burden on system resources, increase noise, and limit the throughput. This paper describes a unique method for incorporating A/D conversion right on the focal plane array. This concept is based on Sigma-Delta sampling, and makes optimum use of the active detector real estate. Combined with modern digital signal processors, such devices will significantly increase data rates off the focal plane. Early conversion to digital format will also decrease the signal susceptibility to noise, lowering the communications bit error rate. Computer modeling of this concept is described, along with results from several simulation runs. A potential application for direct digital conversion is also reviewed. Future uses for this technology could range from scientific instruments to remote sensors, telecommunications gear, medical diagnostic tools, and consumer products.

  20. Modern Directions for Potentiometric Sensors

    PubMed Central

    Bakker, Eric; Chumbimuni-Torres, Karin

    2009-01-01

    This paper gives an overview of the newest developments of polymeric membrane ion-selective electrodes. A short essence of the underlying theory is given, emphasizing how the electromotive force may be used to assess binding constants of the ionophore, and how the selectivity and detection limit are related to the underlying membrane processes. The recent developments in lowering the detection limits of ISEs are described, including recent approaches of developing all solid state ISEs, and breakthroughs in detecting ultra-small quantities of ions at low concentrations. These developments have paved the way to use potentiometric sensors as in ultra-sensitive affinity bioanalysis in conjunction with nanoparticle labels. Recent results establish that potentiometry compares favorably to electrochemical stripping analysis. Other new developments with ion-selective electrodes are also described, including the concept of backside calibration potentiometry, controlled current coulometry, pulsed chronopotentiometry, and localized flash titration with ion-selective membranes to design sensors for the direct detection of total acidity without net sample perturbation. These developments have further opened the field for exciting new possibilities and applications. PMID:19890473

  1. Directional emittance corrections for thermal infrared imaging

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Wright, Robert E., Jr.; Puram, Chith K.; Alderfer, David W.

    1992-01-01

    A simple measurement technique for measuring the variation of directional emittance of surfaces at various temperatures using commercially available radiometric IR imaging systems was developed and tested. This technique provided the integrated value of directional emittance over the spectral bandwidth of the IR imaging system. The directional emittance of flat black lacquer and red stycast, an epoxy resin, measured using this technique were in good agreement with the predictions of the electromagnetic theory. The data were also in good agreement with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  2. Directional emittance corrections for thermal infrared imaging

    NASA Astrophysics Data System (ADS)

    Daryabeigi, Kamran; Wright, Robert E., Jr.; Puram, Chith K.; Alderfer, David W.

    1992-04-01

    A simple measurement technique for measuring the variation of directional emittance of surfaces at various temperatures using commercially available radiometric IR imaging systems was developed and tested. This technique provided the integrated value of directional emittance over the spectral bandwidth of the IR imaging system. The directional emittance of flat black lacquer and red stycast, an epoxy resin, measured using this technique were in good agreement with the predictions of the electromagnetic theory. The data were also in good agreement with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  3. Directional emittance corrections for thermal infrared imaging

    NASA Astrophysics Data System (ADS)

    Daryabeigi, Kamran; Wright, Robert E., Jr.; Puram, Chith K.; Alderfer, David W.

    A simple measurement technique for measuring the variation of directional emittance of surfaces at various temperatures using commercially available radiometric IR imaging systems was developed and tested. This technique provided the integrated value of directional emittance over the spectral bandwidth of the IR imaging system. The directional emittance of flat black lacquer and red stycast, an epoxy resin, measured using this technique were in good agreement with the predictions of the electromagnetic theory. The data were also in good agreement with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  4. Fluctuations along supersymmetric flat directions during inflation

    SciTech Connect

    Enqvist, Kari; Figueroa, Daniel G. [Physics Department, University of Helsinki and Helsinki Institute of Physics, P.O. Box 64, FI-00014, Helsinki (Finland); Rigopoulos, Gerasimos, E-mail: kari.enqvist@helsinki.fi, E-mail: daniel.figueroa@helsinki.fi, E-mail: rigopoulos@physik.rwth-aachen.de [Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen, D-52056, Aachen (Germany)

    2012-01-01

    We consider a set of scalar fields, consisting of a single flat direction and one or several non-flat directions. We take our cue from the MSSM, considering separately D-flat and F-flat directions, but our results apply to any supersymmetric scenario containing flat directions. We study the field fluctuations during pure de Sitter inflation, following the evolution of the infrared modes by numerically solving the appropriate Langevin equations. We demonstrate that for the Standard Model U(1){sub Y}, SU(2){sub L} or SU(3){sub c} gauge couplings, as well as for large enough Yukawa couplings, the fluctuations along the non-flat directions effectively block the fluctuations along the flat directions. The usual expected behaviour (?{sup 2})?N, with N the number of e-folds, may be strongly violated, depending on the coupling strengths. As a consequence, those cosmological considerations, which are derived assuming that during inflation flat directions fluctuate freely, should be revised.

  5. Future directions of ecosystem science

    USGS Publications Warehouse

    Baron, Jill; Galvin, Kathleen A.

    1990-01-01

    Scientific knowledge about ecosystem structure and function has expanded greatly during the past few decades. Terrestrial and aquatic nutrient cycling, ecosystem energetics, population dynamics, belowground processes, and food webs have been studied at the plot, stand, watershed, and landscape levels at many locations around the globe. Ideas about terrestrial-atmospheric interactions and human interference in these processes have changed dramatically. There is new appreciation of the need to incorporate into ecosystem studies the interactions between human populations and the ecosystem, not only because humans affect ecosystem processes, but because these systems support human populations (Glantz 1988, Holden 1988, Parry et al. 1988, WCED 1987). Recent advances in ecosystem science are due, in part, to technological improvements in computing power, new laboratory and field physical and chemical analytical techniques, and satellite imagery for remote sensing of Earth's structure and dynamics. Modeling and geographic information systems have provided the capability for integrating multiple data sets with process simulations to generate hypotheses about regional ecosystem function. Concurrent with these scientific developments has been a growing concern about the links between the health of the environment and world-wide industrial, land, and resource-management practices. Environmental damage at the local level was widely recognized in the 1960s, prompting the environmental movement of that decade. Regional environmental problems with multiple effects and politically difficult solutions have been perceived more recently; the issue of acidic deposition provides an example of such a second-generation concern (Clark and Holling 1985). Today there is a growing awareness of global-scale environmental degradation brought about by the combined actions of all peoples on Earth (Clark 1989, Woodmansee et al. 1988). The three levels of environmental concern--local, regional, and global--have not replaced one another (Clark and Holling 1985). Instead, the effects are superimposed, creating what some perceive as impending global environmental crisis (Clark 1989, MacNeill 1989, WCED 1987). Public demands are developing for economic, political, social, and environmental efforts directed toward creating a state of global sustainability.

  6. MAPPING DIRECTLY IMAGED GIANT EXOPLANETS

    SciTech Connect

    Kostov, Veselin [Department of Physics and Astronomy, Johns Hopkins University, 366 Bloomberg Center, 3400 North Charles Street, Baltimore, MD 21218 (United States)] [Department of Physics and Astronomy, Johns Hopkins University, 366 Bloomberg Center, 3400 North Charles Street, Baltimore, MD 21218 (United States); Apai, Daniel, E-mail: vkostov@pha.jhu.edu [Department of Astronomy, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85718 (United States)] [Department of Astronomy, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85718 (United States)

    2013-01-01

    With the increasing number of directly imaged giant exoplanets, the current atmosphere models are often not capable of fully explaining the spectra and luminosity of the sources. A particularly challenging component of the atmosphere models is the formation and properties of condensate cloud layers, which fundamentally impact the energetics, opacity, and evolution of the planets. Here we present a suite of techniques that can be used to estimate the level of rotational modulations these planets may show. We propose that the time-resolved observations of such periodic photometric and spectroscopic variations of extrasolar planets due to their rotation can be used as a powerful tool to probe the heterogeneity of their optical surfaces. In this paper, we develop simulations to explore the capabilities of current and next-generation ground- and space-based instruments for this technique. We address and discuss the following questions: (1) what planet properties can be deduced from the light curve and/or spectra, and in particular can we determine rotation periods, spot coverage, spot colors, and spot spectra?; (2) what is the optimal configuration of instrument/wavelength/temporal sampling required for these measurements?; and (3) can principal component analysis be used to invert the light curve and deduce the surface map of the planet? Our simulations describe the expected spectral differences between homogeneous (clear or cloudy) and patchy atmospheres, outline the significance of the dominant absorption features of H{sub 2}O, CH{sub 4}, and CO, and provide a method to distinguish these two types of atmospheres. Assuming surfaces with and without clouds for most currently imaged planets the current models predict the largest variations in the J band. Simulated photometry from current and future instruments is used to estimate the level of detectable photometric variations. We conclude that future instruments will be able to recover not only the rotation periods, cloud cover, cloud colors, and spectra but even cloud evolution. We also show that a longitudinal map of the planet's atmosphere can be deduced from its disk-integrated light curves.

  7. AIRTV: Broadband Direct to Aircraft

    NASA Astrophysics Data System (ADS)

    Sorbello, R.; Stone, R.; Bennett, S. B.; Bertenyi, E.

    2002-01-01

    Airlines have been continuously upgrading their wide-body, long-haul aircraft with IFE (in-flight entertainment) systems that can support from 12 to 24 channels of video entertainment as well as provide the infrastructure to enable in-seat delivery of email and internet services. This is a direct consequence of increased passenger demands for improved in-flight services along with the expectations that broadband delivery systems capable of providing live entertainment (news, sports, financial information, etc.) and high speed data delivery will soon be available. The recent events of Sept. 11 have slowed the airline's upgrade of their IFE systems, but have also highlighted the compelling need for broadband aeronautical delivery systems to include operational and safety information. Despite the impact of these events, it is estimated that by 2005 more than 3000 long haul aircraft (servicing approximately 1 billion passengers annually) will be fully equipped with modern IFE systems. Current aircraft data delivery systems, which use either Inmarsat or NATS, are lacking in bandwidth and consequently are unsuitable to satisfy passenger demands for broadband email/internet services or the airlines' burgeoning data requirements. Present live video delivery services are limited to regional coverage and are not readily expandable to global or multiregional service. Faced with a compelling market demand for high data transport to aircraft, AirTV has been developing a broadband delivery system that will meet both passengers' and airlines' needs. AirTV is a global content delivery system designed to provide a range of video programming and data services to commercial airlines. When AirTV is operational in 2004, it will provide a broadband connection directly to the aircraft, delivering live video entertainment, internet/email service and essential operational and safety data. The system has been designed to provide seamless global service to all airline routes except for those over the poles. The system consists of a constellation of 4 geostationary satellites covering the earth and delivering its signals to the aircraft at S band (2.52 -2.67 GHz). The S-band spectrum is ideal for this application since it is allocated on a primary basis by the ITU for global broadcast service. The AirTV service is expected to begin in 2004 and should be unencumbered by adjacent satellite interference due to near completion of the ITU coordination process. Each satellite will deliver four 20 Mbps QPSK data streams consisting of multiplexed compressed digital video channels and IP data over the full global beam coverage. The 80 Mbps capacity of each satellite will provide approximately 60 video channels while still allocating 40 Mbits to data services. The combined constellation capacity of 320 Mbits will significantly exceed the capacity of any similar existing or currently planned global satellite system. In addition, the simplicity of the 4-satellite approach is the most cost effective means to deliver high bandwidth globally. Return links, which are required for internet service, will be provided through the existing Inmarsat Aero-H system already onboard virtually all long haul aircraft and will provide return data rates from the aircraft as high as 432 kbps. integrated receiver/decoder (IRD) assembly. The phased array antenna, a key technology element, is being developed by AirTV's strategic partner, CMC Electronics. This antenna is a scaled version of CMC's Inmarsat Aero H antenna and is capable of scanning to 5 degrees above the horizon. Wide angle scanning up to 85 degrees from zenith is necessary for aircraft traversing the northernmost latitudes on transoceanic routes. AirTV has designed both the satellite coverage and aircraft antenna performance to ensure that high signal quality is maintained along all non-polar airline routes. AirTV will be the future of aeronautical broadband delivery. It has been designed specifically for global services and uses the ideal spectrum for this application. It will revolutionize the delivery of content t

  8. Mixed conducting catalyst support materials for the direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Lasch, K.; Hayn, G.; Jörissen, L.; Garche, J.; Besenhardt, O.

    Finely dispersed Pt- and Pt/Ru-particles have been deposited on high surface-area ruthenium dioxide (RuO 2) using the Petrow and Allen method [U.S. Patent No. 4,044,193 (23 August 1977)]. RuO 2 has been synthesized according to different preparation methods. It turned out that the product showing the highest surface area could be produced by a simple fast precipitation method. The electrocatalytic activities of catalysts on different ruthenium oxide supports have been investigated in half-cell experiments by stationary current voltage measurements. Pt/Ru-catalysts deposited on a Vulcan XC-72 carbon black have been used for comparison. X-ray analysis methods (XRD, EDX) have been used to characterize the composition and crystallinity of the materials and their geometric surface areas have been determined by the BET method. It turned out that the electric conductivity of the RuO 2 materials was comparable to that observed for Vulcan XC-72. Furthermore, RuO 2 materials having a BET surface area above 125 m 2/g could be synthesized. (Vulcan XC-71: ˜250 m 2/g). Surprisingly, no significant electrochemical activity was found when Pt/Ru was deposited on freshly precipitated hydrous RuO 2. Deposition of noble metals on calcined RuO 2 resulted in electrochemical activities comparable to the ones obtained for the Vulcan XC-72 support. Thus, no extraordinary enhancement of catalytic activity for the methanol has been observed when RuO 2 oxide was used as a mixed conducting catalyst support.

  9. Direct manipulation of virtual objects

    NASA Astrophysics Data System (ADS)

    Nguyen, Long K.

    Interacting with a Virtual Environment (VE) generally requires the user to correctly perceive the relative position and orientation of virtual objects. For applications requiring interaction in personal space, the user may also need to accurately judge the position of the virtual object relative to that of a real object, for example, a virtual button and the user's real hand. This is difficult since VEs generally only provide a subset of the cues experienced in the real world. Complicating matters further, VEs presented by currently available visual displays may be inaccurate or distorted due to technological limitations. Fundamental physiological and psychological aspects of vision as they pertain to the task of object manipulation were thoroughly reviewed. Other sensory modalities -- proprioception, haptics, and audition -- and their cross-interactions with each other and with vision are briefly discussed. Visual display technologies, the primary component of any VE, were canvassed and compared. Current applications and research were gathered and categorized by different VE types and object interaction techniques. While object interaction research abounds in the literature, pockets of research gaps remain. Direct, dexterous, manual interaction with virtual objects in Mixed Reality (MR), where the real, seen hand accurately and effectively interacts with virtual objects, has not yet been fully quantified. An experimental test bed was designed to provide the highest accuracy attainable for salient visual cues in personal space. Optical alignment and user calibration were carefully performed. The test bed accommodated the full continuum of VE types and sensory modalities for comprehensive comparison studies. Experimental designs included two sets, each measuring depth perception and object interaction. The first set addressed the extreme end points of the Reality-Virtuality (R-V) continuum -- Immersive Virtual Environment (IVE) and Reality Environment (RE). This validated, linked, and extended several previous research findings, using one common test bed and participant pool. The results provided a proven method and solid reference points for further research. The second set of experiments leveraged the first to explore the full R-V spectrum and included additional, relevant sensory modalities. It consisted of two full-factorial experiments providing for rich data and key insights into the effect of each type of environment and each modality on accuracy and timeliness of virtual object interaction. The empirical results clearly showed that mean depth perception error in personal space was less than four millimeters whether the stimuli presented were real, virtual, or mixed. Likewise, mean error for the simple task of pushing a button was less than four millimeters whether the button was real or virtual. Mean task completion time was less than one second. Key to the high accuracy and quick task performance time observed was the correct presentation of the visual cues, including occlusion, stereoscopy, accommodation, and convergence. With performance results already near optimal level with accurate visual cues presented, adding proprioception, audio, and haptic cues did not significantly improve performance. Recommendations for future research include enhancement of the visual display and further experiments with more complex tasks and additional control variables.

  10. Directional detection of dark matter streams

    E-print Network

    Ciaran A. J. O'Hare; Anne M. Green

    2014-11-11

    Directional detection of WIMPs, in which the energies and directions of the recoiling nuclei are measured, currently presents the only prospect for probing the local velocity distribution of Galactic dark matter. We investigate the extent to which future directional detectors would be capable of probing dark matter substructure in the form of streams. We analyse the signal expected from a Sagittarius-like stream and also explore the full parameter space of stream speed, direction, dispersion and density. Using a combination of non-parametric directional statistics, a profile likelihood ratio test and Bayesian parameter inference we find that within acceptable exposure times (O(10) kg yr for cross sections just below the current exclusion limits) future directional detectors will be sensitive to a wide range of stream velocities and densities. We also examine and discuss the importance of the energy window of the detector.

  11. Directional detection of dark matter streams

    NASA Astrophysics Data System (ADS)

    O'Hare, Ciaran A. J.; Green, Anne M.

    2014-12-01

    Directional detection of weakly interacting massive particles, in which the energies and directions of the recoiling nuclei are measured, currently presents the only prospect for probing the local velocity distribution of Galactic dark matter. We investigate the extent to which future directional detectors would be capable of probing dark matter substructure in the form of streams. We analyze the signal expected from a Sagittarius-like stream and also explore the full parameter space of stream speed, direction, dispersion and density. Using a combination of nonparametric directional statistics, a profile likelihood ratio test and Bayesian parameter inference we find that within acceptable exposure times [O (10 ) kg yr for cross sections just below the current exclusion limits] future directional detectors will be sensitive to a wide range of stream velocities and densities. We also examine and discuss the importance of the energy window of the detector.

  12. Bedform alignment in directionally varying flows

    USGS Publications Warehouse

    Rubin, D.M.; Hunter, R.E.

    1987-01-01

    Many kinds of sediment bedforms are presumed to trend either normal or parallel to the direction of sediment transport. For this reason, the trend of bedforms observed by remote sensing or by field observations is commonly used as an indicator of the direction of sediment transport. Such presumptions regarding bedform trend were tested experimentally in bidirectional flows by rotating a sand-covered board in steady winds. Transverse, oblique, and longitudinal bedforms were created by changing only two parameters: the angle between the two winds and the proportions of sand transported in the two directions. Regardless of whether the experimental bedforms were transverse, oblique, or longitudinal (as defined by the bedform trend relative to the resultant transport direction), they all had trends that yielded the maximum gross transport across the bedforms. The fact that many of the experimental bedforms were neither transverse nor parallel to the resultant transport direction suggests that transport directions cannot be accurately determined by presuming such alignment.

  13. Formic acid oxidation in a polymer electrolyte fuel cell: A real-time mass-spectrometry study

    Microsoft Academic Search

    M. Weber; J. T. Wang; S. Wasmus; R. F. Savinell

    1996-01-01

    The electro-oxidation of formic acid was studied in a direct-oxidation polymer-electrolyte fuel cell at 170 C using real-time mass spectrometry. The results are compared with those obtained for methanol oxidation under the same conditions. Formic acid was electrochemically more active than methanol on both Pt-black and Pt-Ru catalysts. The polarization potential of formic acid oxidation was ca. 90 to 100

  14. Combining search directions using gradient flows

    Microsoft Academic Search

    Javier M. Moguerza; Francisco J. Prieto

    2003-01-01

    .  ?The efficient combination of directions is a significant problem in line search methods that either use negative curvature,\\u000a or wish to include additional information such as the gradient or different approximations to the Newton direction. \\u000a \\u000a In this paper we describe a new procedure to combine several of these directions within an interior-point primal-dual algorithm.\\u000a Basically, we combine in an efficient

  15. A parametric study of directional sea modeling

    E-print Network

    Whatley, Christopher Paul

    1990-01-01

    examines the effect due to wave loading described by the directional sea spectrum on the response of offshore structures. The use of directional seas in design is expected to provide a better representation of the ocean surface and associated kinematics... as compared to unidirectional theory. This in turn should provide a basis for minimizing the overdesign of offshore structures. Several of the more popular directional wave spreading functions are intro- duced. A parametric study is conducted in order...

  16. Does Economic Integration Cause Foreign Direct Investment?

    Microsoft Academic Search

    Massimo Motta; George Norman

    1996-01-01

    The authors analyze the effect of economic integration on oligopolists' international trade and foreign direct investment activities, using a three-country, three-firm model. Increased country size leads to dispersed foreign direct investment, while improved market accessibility leads to export-platform foreign direct investment. Increased intraregional market accessibility prompts outside firms to invest in the regional bloc, reducing product prices, profits of intrabloc

  17. NOSS-SCAT wind direction alias removal

    NASA Technical Reports Server (NTRS)

    Shanmugan, K. S.; Narayanan, V.; Stiles, J.

    1982-01-01

    The use of automated algorithms for removing aliases in NOSS-SCAT data is reported. The algorithms used for alias removal consist of histogram analysis, local averaging and curve fitting. The histogram analysis is used to determine the degree of homogeneity of the wind field defined by the largest probability alias vector at each grid point. The alias directions are compared with the preferred direction at each grid location and one of the multiple aliases is chosen as the true direction.

  18. Machine-Learning Research Four Current Directions

    Microsoft Academic Search

    Thomas G. Dietterich

    1997-01-01

    Machine Learning research has been making great progress in many directions. This article summarizes four ofthese directions and discusses some current open problems. The four directions are (a) improving classificationaccuracy by learning ensembles of classifiers, (b) methods for scaling up supervised learning algorithms, (c)reinforcement learning, and (d) learning complex stochastic models.1 IntroductionThe last five years have seen an explosion in

  19. Directed diffusion for wireless sensor networking

    Microsoft Academic Search

    Chalermek Intanagonwiwat; Ramesh Govindan; Deborah Estrin; John S. Heidemann; Fabio Silva

    2003-01-01

    Advances in processor, memory, and radio technology will enable small and cheap nodes capable of sensing, communication, and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed-diffusion paradigm for such coordination. Directed diffusion is data-centric in that all communication is for named data. All nodes in a directed-diffusion-based

  20. Direct-conversion RF receiver design

    Microsoft Academic Search

    Won Namgoong; Teresa H. Meng

    2001-01-01

    The direct-conversion radio-frequency receiver architecture promises superior performances in power, size, and cost over existing superheterodyne-based receivers. The use of direct-conversion receiver (DCR) architecture, however, has been limited due to two well-known problems, namely, the 1\\/f noise and the direct-current offset noise, to which conventional architectures are less sensitive. This paper analyzes these noise effects on reception performance of a

  1. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming (Los Alamos, NM); Gottesfeld, Shimshon (Los Alamos, NM)

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source. Water loss from the cell is minimized by making the conductive cathode assembly hydrophobic and the conductive anode assembly hydrophilic.

  2. Rupture directivity of small earthquakes at Parkfield

    NASA Astrophysics Data System (ADS)

    Kane, Deborah L.; Shearer, Peter M.; Goertz-Allmann, Bettina P.; Vernon, Frank L.

    2013-01-01

    AbstractTheoretical modeling of strike-slip ruptures along a bimaterial interface suggests that earthquakes initiating on the interface will have a preferred rupture <span class="hlt">direction</span>. We test this model with 450 small earthquakes (2 < M < 5) from Parkfield, California, to look for evidence of consistent rupture <span class="hlt">directivity</span> along the San Andreas Fault. We analyze azimuthal variations in earthquake source spectra after applying an iterative correction for wave propagation effects. Our approach avoids <span class="hlt">directly</span> modeling source spectra because these models generally assume symmetric rupture; instead, we look for azimuthal variations in the amplitudes of the source spectra over specified frequency bands. Our overall results show similar proportions of events exhibiting characteristics of rupture <span class="hlt">directivity</span> toward either the southeast or northwest. However, the proportion of events with southeast rupture <span class="hlt">directivity</span> increases as we limit the data set to larger magnitudes, with 70% of the 46 events M > 3 exhibiting southeast rupture characteristics. Some spatial and temporal variability in rupture <span class="hlt">directivity</span> is also apparent. We observe a higher proportion of northwest <span class="hlt">directivity</span> ruptures following the 2004 M 6 Parkfield earthquake, which ruptured toward the northwest. Our results are generally consistent with the preferred southeast rupture <span class="hlt">directivity</span> model but suggest that <span class="hlt">directivity</span> is likely due to several contributing factors.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950026828&hterms=religious+practices&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dreligious%2Bpractices"><span id="translatedtitle">NASA <span class="hlt">directives</span> master list and index</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1995-01-01</p> <p>This handbook sets forth in two parts, Master List of Management <span class="hlt">Directives</span> and Index to NASA Management <span class="hlt">Directives</span>, the following information for the guidance of users of the NASA Management <span class="hlt">Directives</span> System. Chapter 1 contains introductory information material on how to use this handbook. Chapter 2 is a complete master list of agencywide management <span class="hlt">directives</span>, describing each <span class="hlt">directive</span> by type, number, effective date, expiration date, title, and organization code of the office responsible for the <span class="hlt">directive</span>. Chapter 3 includes a consolidated numerical list of all delegations of authority and a breakdown of such delegation by the office or center to which special authority is assigned. Chapter 4 sets forth a consolidated list of all NASA handbooks (NHB's) and important footnotes covering the control and ordering of such documents. Chapter 5 is a consolidated list of NASA management <span class="hlt">directives</span> applicable to the Jet Propulsion Laboratory. Chapter 6 is a consolidated list of NASA regulations published in the Code of Federal Regulations. Chapter 7 is a consolidated list of NASA regulations published in Title 14 of the Code of Federal Regulations. Complementary manuals to the NASA Management <span class="hlt">Directives</span> System are described in Chapter 8. The second part contains an in depth alphabetical index to all NASA management <span class="hlt">directives</span> other than handbooks, most of which are indexed by titles only.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=PUBMED&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/10286449"><span id="translatedtitle">Advance <span class="hlt">directives</span> compatible with Catholic moral principles.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hamel, R P</p> <p>1988-04-01</p> <p>Decisions regarding life-sustaining treatment for incompetent patients are typically difficult and stressful for surrogate or proxy decision makers. Although substituted judgment and best interest provisions are helpful to next of kin or guardian and help replicate an incapacitated patient's wishes, a more definitive expression of treatment preferences is needed. Advance <span class="hlt">directives</span> allow currently competent persons to express their wishes about medical treatment before a possible incapacitating situation. Such <span class="hlt">directives</span> seek to realize basic values of human dignity, respect for self-determination and human life, and communication and discussion with the person concerning treatment. Three types of <span class="hlt">directives</span> are the living will or instruction <span class="hlt">directive</span>, proxy <span class="hlt">directive</span> or durable power of attorney, and a combination of the two. Legislative concerns over advance <span class="hlt">directives</span> mainly focus on possible legal euthanasia, patient protection, ambiguous language, and other inadequacies. Catholic healthcare facilities can respond to concerns about advance <span class="hlt">directives</span> in four positive ways: Make information about <span class="hlt">directives</span> available to patients and providers. Contribute to constructive debate in states without legislation. Include provisions for proxy decision making in states with existing patients' bill of rights. Consider legislation to protect physicians from litigation when patients' written <span class="hlt">directives</span> are followed. PMID:10286449</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://arxiv.org/pdf/astro-ph/0506308v3"><span id="translatedtitle">Fast <span class="hlt">directional</span> continuous spherical wavelet transform algorithms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>J. D. McEwen; M. P. Hobson; D. J. Mortlock; A. N. Lasenby</p> <p>2006-05-23</p> <p>We describe the construction of a spherical wavelet analysis through the inverse stereographic projection of the Euclidean planar wavelet framework, introduced originally by Antoine and Vandergheynst and developed further by Wiaux et al. Fast algorithms for performing the <span class="hlt">directional</span> continuous wavelet analysis on the unit sphere are presented. The fast <span class="hlt">directional</span> algorithm, based on the fast spherical convolution algorithm developed by Wandelt and Gorski, provides a saving of O(sqrt(Npix)) over a <span class="hlt">direct</span> quadrature implementation for Npix pixels on the sphere, and allows one to perform a <span class="hlt">directional</span> spherical wavelet analysis of a 10^6 pixel map on a personal computer.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://hdl.handle.net/2060/19930094447"><span id="translatedtitle">Experiences with Flow-<span class="hlt">direction</span> Instruments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eckert, B</p> <p>1941-01-01</p> <p>The method of recording the <span class="hlt">direction</span> of flows on the basis of the hydrodynamic zero-point measurement has now reached a certain limit, in spite of the good results achieved. While the available flow-<span class="hlt">direction</span> devices are accurate enough for many purposes, they are all insufficient for perfectly exact prediction of the flow <span class="hlt">direction</span>. The next problem will be to achieve a point-by point flow-<span class="hlt">direction</span> record, whereby the test procedure must be simplified, accelerated, and the degree of accuracy of the test data improved.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.lehigh.edu/~sdw1/nsfws.pdf"><span id="translatedtitle">MANUFACTURING LOGISTICS RESEARCH: TAXONOMY AND <span class="hlt">DIRECTIONS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Wu, David</p> <p></p> <p>MANUFACTURING LOGISTICS RESEARCH: TAXONOMY AND <span class="hlt">DIRECTIONS</span> S. DAVID WU Lehigh University, Bethlehem formed in the workshop. To convey this vision we suggest a taxonomy that characterizes research problems</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=DOE-PATENT-XML&redirectUrl=http://www.osti.gov/doepatents/biblio/963792"><span id="translatedtitle">Ionization based multi-<span class="hlt">directional</span> flow sensor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Chorpening, Benjamin T. (Morgantown, WV); Casleton, Kent H. (Morgantown, WV)</p> <p>2009-04-28</p> <p>A method, system, and apparatus for conducting real-time monitoring of flow (airflow for example) in a system (a hybrid power generation system for example) is disclosed. The method, system and apparatus measure at least flow <span class="hlt">direction</span> and velocity with minimal pressure drop and fast response. The apparatus comprises an ion source and a multi-<span class="hlt">directional</span> collection device proximate the ion source. The ion source is configured to generate charged species (electrons and ions for example). The multi-<span class="hlt">directional</span> collection source is configured to determine the <span class="hlt">direction</span> and velocity of the flow in real-time.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19840026250&hterms=water+pollution+control&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2522water%2Bpollution%2Bcontrol%2522"><span id="translatedtitle">Master list and index to NASA <span class="hlt">directives</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1984-01-01</p> <p>All NASA management <span class="hlt">directives</span> in force as of August 1, 1984 are listed by major subject headings showing number, effective date, title, responsible office, and distribution code. Delegations of authority in print by that date are listed numerically as well as by the installation or office to which special authority is assigned. Other consolidated lists show all management handbooks, <span class="hlt">directives</span> applicable to the Jet Propulsion Laboratory, <span class="hlt">directives</span> published in the Code of Federal Regulations, complementary manuals, and NASA safety standards. Distribution policies and instructions for ordering <span class="hlt">directives</span> are included.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19830003611&hterms=yellow+fever&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dyellow%2Bfever"><span id="translatedtitle">Master list and index to NASA <span class="hlt">directives</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1982-01-01</p> <p>All NASA management <span class="hlt">directives</span> in force as of August 1, 1982 are listed by major subject headings showing number, effective data, title, responsible office, and distribution code. Delegations of authority in print by that date are listed numerically as well as by the installation or office to which special authority is assigned. Other consolidated lists show all management handbooks, <span class="hlt">directives</span> applicable to the Jet Propulsion Laboratory, <span class="hlt">directions</span> published in the Code of Federal Regulations, complementary manuals, and NASA safety standards. Distribution policies and instructions for ordering <span class="hlt">directives</span> are included.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=ERIC&redirectUrl=http://files.eric.ed.gov/fulltext/EJ781881.pdf"><span id="translatedtitle">Self-<span class="hlt">Directed</span> Learning by Undereducated Adults</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Terry, Marion</p> <p>2006-01-01</p> <p>In 2002-03, a qualitative study examined the experiences of 70 stakeholders connected to two community-based adult literacy programs in Manitoba, Canada. Self-<span class="hlt">directed</span> learning was one of several elements that these research participants considered essential to the learning process. These literacy stakeholders defined self-<span class="hlt">directed</span> learning as a…</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20050000122&hterms=introduction+data+mining&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dintroduction%2Bdata%2Bmining"><span id="translatedtitle">Circular Data Images for <span class="hlt">Directional</span> Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morpet, William J.</p> <p>2004-01-01</p> <p><span class="hlt">Directional</span> data includes vectors, points on a unit sphere, axis orientation, angular <span class="hlt">direction</span>, and circular or periodic data. The theoretical statistics for circular data (random points on a unit circle) or spherical data (random points on a unit sphere) are a recent development. An overview of existing graphical methods for the display of <span class="hlt">directional</span> data is given. Cross-over occurs when periodic data are measured on a scale for the measurement of linear variables. For example, if angle is represented by a linear color gradient changing uniformly from dark blue at -180 degrees to bright red at +180 degrees, the color image will be discontinuous at +180 degrees and -180 degrees, which are the same location. The resultant color would depend on the <span class="hlt">direction</span> of approach to the cross-over point. A new graphical method for imaging <span class="hlt">directional</span> data is described, which affords high resolution without color discontinuity from "cross-over". It is called the circular data image. The circular data image uses a circular color scale in which colors repeat periodically. Some examples of the circular data image include <span class="hlt">direction</span> of earth winds on a global scale, rocket motor internal flow, earth global magnetic field <span class="hlt">direction</span>, and rocket motor nozzle vector <span class="hlt">direction</span> vs. time.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://www.cognitivegiscience.psu.edu/pdfs/klippel2007linguistic.pdf"><span id="translatedtitle">Linguistic and Nonlinguistic Turn <span class="hlt">Direction</span> Concepts</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Alexander Klippel; Daniel R. Montello</p> <p>2007-01-01</p> <p>This paper discusses the conceptualization of turn <span class="hlt">directions</span> along traveled routes. Foremost, we are interested in the influence that language has on the conceptualization of turn <span class="hlt">directions</span>. Two experiments are presented that contrast the way people group turns into similarity classes when they expect to verbally label the turns, as compared to when they do not. We are particularly interested</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=ERIC&redirectUrl=http://eric.ed.gov/?q=blumen&id=EJ146009"><span id="translatedtitle">Vicarious and <span class="hlt">Direct</span> Achievement Patterns in Adulthood</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lipman-Blumen, Jean; Leavitt, Harold J.</p> <p>1976-01-01</p> <p>This paper presents a typology of <span class="hlt">direct</span> and vicarious achievement orientations relevant to adult problems. <span class="hlt">Direct</span> and vicarious achievement patterns are related to sex role socialization and sex-linked occupational choice. Recommendations are developed for reevaluating and redesigning adult occupational and interpersonal roles which would take…</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://eprints.soton.ac.uk/41692/01/2962.pdf"><span id="translatedtitle">Extraordinary stability of femtosecond <span class="hlt">direct</span> written structures</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Erica Bricchi; Peter G. Kazansky</p> <p></p> <p>We report novel results on the stability of femtosecond <span class="hlt">direct</span> written structures: a silica sample previously irradiated with ultrashort pulses was annealed at increasing temperatures till 1400° C where it crystallized. Our results show that the birefringent <span class="hlt">direct</span> written structures are stable till a temperature close to the glass transition of silica. After annealing at a temperature as high as</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://www.maths.manchester.ac.uk/~nareports/narep197.pdf"><span id="translatedtitle">OPTIMIZATION BY <span class="hlt">DIRECT</span> SEARCH IN MATRIX COMPUTATIONS</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>NICHOLAS J. HIGHAMt</p> <p>1993-01-01</p> <p>A <span class="hlt">direct</span> search method attempts to maximize a function f l R using function values only. Many questions about the stability and accuracy of algorithms in matrix computations can be expressed in terms of the maximum value ofsome easily computable function f. For a variety of algorithms it is shown that <span class="hlt">direct</span> search is capable of revealing instability or poor</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://spo.nmfs.noaa.gov/SSRF/SSRF93.pdf"><span id="translatedtitle"><span class="hlt">DIRECTING</span> THE MOVEMENT OF FISH WITH ELECTRICITY</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p></p> <p></p> <p><span class="hlt">DIRECTING</span> THE MOVEMENT OF FISH WITH ELECTRICITY Marine Biological Laboratory APR 21 1953 WOODS HOLE, Albert M. Day, Director <span class="hlt">DIRECTING</span> THE MOVH-IENT OF FISH WITH ELECTRICITY by Alberton L. McLain Fishery of an electrical leading device 21 Literature cited. ..,...,..,..........·· 2k ILLUSTRATIONS Figure Page 1. Diagram</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=ERIC&redirectUrl=http://eric.ed.gov/?q=mn&pg=3&id=EJ921305"><span id="translatedtitle">Spectroscopy and <span class="hlt">Direct</span> Products: Simpler yet Deeper</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Kettle, Sidney F. A.</p> <p>2010-01-01</p> <p>When irreducible representations are given in diagrammatic form, it is possible to show <span class="hlt">direct</span> products pictorially. By giving a similar description of the electric vector associated with a light wave, group-theoretical selection rules (the requirement of a totally symmetric <span class="hlt">direct</span> product) can also be shown in pictorial form. The [upsilon](CO)…</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/2336002"><span id="translatedtitle">Relative <span class="hlt">direction</span> determination in mobile computing networks</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Antonis Kalis; Theodore AntonakopouloS</p> <p>2001-01-01</p> <p>A novel relative <span class="hlt">direction</span> determination method is presented for stations of mobile computing networks. The method uses a switched beam array for determining the <span class="hlt">direction</span> of arrival (DOA) of the incident electromagnetic field in a time efficient way, in order to confront the strict timing requirements of packet switching networks. Additionally, the method associates certain MAC layer functions with different</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.hopkinsmedicine.org/cellbio/devreotes/172.pdf"><span id="translatedtitle"><span class="hlt">Directional</span> Sensing Orients Cell Migration and Polarization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Devreotes, Peter</p> <p></p> <p><span class="hlt">Directional</span> Sensing Orients Cell Migration and Polarization Cell migration is a complex process toward the source of chemoattractant and uropod retraction in the rear and thus orients the <span class="hlt">direction</span> toward sites of infection. In addition to its roles in normal physiology, inappropriate migration</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://fbs.admin.utah.edu/download/AP/Hosp%20EE%20DirDepForm.pdf"><span id="translatedtitle">Accounts Payable EMPLOYEE <span class="hlt">DIRECT</span> DEPOSIT AUTHORIZATION FORM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Tipple, Brett</p> <p></p> <p>Payroll Setup Change <span class="hlt">Direct</span> Deposit Information Cancel <span class="hlt">Direct</span> Deposit HOSPITAL ACCOUNTS PAYABLE, 127 SOUTH bank information, or lack of Payee notification when a bank account is closed.1 Note: Changes to their depository accounts. Payee Information Important Notice Unlike payroll deposits, Accounts Payable cannot</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://arxiv.org/pdf/1107.1414v2"><span id="translatedtitle">On the Spectrum of <span class="hlt">Direct</span> Gaugino Mediation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Roberto Auzzi; Amit Giveon; Sven Bjarke Gudnason; Tomer Shacham</p> <p>2011-09-22</p> <p>In <span class="hlt">direct</span> gauge mediation, the gaugino masses are anomalously small, giving rise to a split SUSY spectrum. Here we investigate the superpartner spectrum in a minimal version of "<span class="hlt">direct</span> gaugino mediation." We find that the sfermion masses are comparable to those of the gauginos - even in the hybrid gaugino-gauge mediation regime - if the messenger scale is sufficiently small.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://stoltz.caltech.edu/publications/41-2004.pdf"><span id="translatedtitle">Pd-Catalyzed Cyclizations <span class="hlt">Direct</span> Oxidative Heck</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Stoltz, Brian M.</p> <p></p> <p>Pd-Catalyzed Cyclizations <span class="hlt">Direct</span> Oxidative Heck Cyclizations: Intramolecular Fujiwara (Scheme 1a). A potentially more efficient process would involve oxidative coupling of an unfunction olefins (e.g., acrylate esters).[3] In fact, the <span class="hlt">direct</span> intramolecular oxidative arene/ olefin coupling (i</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=ERIC&redirectUrl=http://eric.ed.gov/?q=schizophrenia&pg=6&id=EJ839651"><span id="translatedtitle">Stigma and Schizophrenia: <span class="hlt">Directions</span> in Student Training</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Mason, Susan E.; Miller, Rachel</p> <p>2006-01-01</p> <p>The persistence of stigma related to schizophrenia is addressed as a continuing challenge for social work students working in mental health. Student education is best grounded in <span class="hlt">direct</span> clinical work with clients in conjunction with field supervision and classroom education. Through <span class="hlt">direct</span> practice in individual and group sessions, students learn…</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.jasonmcewen.org/papers/moriond2004.pdf"><span id="translatedtitle">A FAST <span class="hlt">DIRECTIONAL</span> CONTINUOUS SPHERICAL WAVELET TRANSFORM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>McEwen, Jason</p> <p></p> <p>A FAST <span class="hlt">DIRECTIONAL</span> CONTINUOUS SPHERICAL WAVELET TRANSFORM J.D. MCEWEN, M.P. HOBSON, A.N. LASENBY algorithm for Antoine and Vandergheynst's (1998) <span class="hlt">directional</span> Continuous Spherical Wavelet Transform (CSWT Spherical Wavelet Transform (CSWT), based on the fast spherical convolution proposed by Wandelt and G´orski6</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://extension.unh.edu/events/files/6FF135BB-E297-3C40-09BE8187C0E55C0F.pdf"><span id="translatedtitle">NH <span class="hlt">Direct</span> Marketing Name(s):_________________________________</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>New Hampshire, University of</p> <p></p> <p>at 603-679-5616 or nada.haddad@unh.edu On-line registration is encouraged. You may register online atNH <span class="hlt">Direct</span> Marketing Conference Name(s):_________________________________ Company Name ______Seafood Quality Program - February 18, 2014 The New Hampshire <span class="hlt">Direct</span> Marketing Conference will offer new</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=FEDREG&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/FR-2012-07-31/pdf/2012-18585.pdf"><span id="translatedtitle">77 FR 45288 - Airworthiness <span class="hlt">Directives</span>; Bombardier, Inc.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-07-31</p> <p>...Airworthiness <span class="hlt">Directives</span>; Bombardier, Inc. AGENCY: Federal Aviation Administration...<span class="hlt">directive</span> (AD) for certain Bombardier, Inc. Model CL-600-1A11 (CL-600), CL-600-2A12...this proposed AD, contact Bombardier, Inc., 400 C[ocirc]te-Vertu Road...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2014&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2014-title30-vol2/pdf/CFR-2014-title30-vol2-sec256-71.pdf"><span id="translatedtitle">30 CFR 256.71 - <span class="hlt">Directional</span> drilling.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 2014-07-01 false <span class="hlt">Directional</span> drilling. 256.71 Section 256.71 Mineral...Extensions § 256.71 <span class="hlt">Directional</span> drilling. In accordance with a BOEM-approved...by the lease. In such circumstances, drilling shall be considered to have...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2013&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2013-title30-vol2/pdf/CFR-2013-title30-vol2-sec256-71.pdf"><span id="translatedtitle">30 CFR 256.71 - <span class="hlt">Directional</span> drilling.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 2013-07-01 false <span class="hlt">Directional</span> drilling. 256.71 Section 256.71 Mineral...Extensions § 256.71 <span class="hlt">Directional</span> drilling. In accordance with a BOEM-approved...by the lease. In such circumstances, drilling shall be considered to have...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2012&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2012-title30-vol2/pdf/CFR-2012-title30-vol2-sec256-71.pdf"><span id="translatedtitle">30 CFR 256.71 - <span class="hlt">Directional</span> drilling.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 2012-07-01 false <span class="hlt">Directional</span> drilling. 256.71 Section 256.71 Mineral...Extensions § 256.71 <span class="hlt">Directional</span> drilling. In accordance with a BOEM-approved...by the lease. In such circumstances, drilling shall be considered to have...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASAADS&redirectUrl=http://adsabs.harvard.edu/abs/2015SPIE.9258E..2YM"><span id="translatedtitle">Planar antenna system for <span class="hlt">direction</span> finding</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mardale, Iulia-Cezara; Cocias, Gabriela; Dumitrascu, Ana; Tamas, Razvan; Berescu, Serban</p> <p>2015-02-01</p> <p>Applications of <span class="hlt">direction</span> finding techniques include detection and localization of pulsed electromagnetic sources. This paper presents the design and analysis of a planar antenna system for <span class="hlt">direction</span> finding. Our proposed system includes 4 hybrid couplers that generate 900 shifted signals, 2 crossover couplers also known as 0dB couplers, two 450 phase shifters, two 00 phase shifters and 4 patch antennas.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASAADS&redirectUrl=http://adsabs.harvard.edu/abs/2009LNCS.5728..413B"><span id="translatedtitle">DBtk: A Toolkit for <span class="hlt">Directed</span> Bigraphs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bacci, Giorgio; Grohmann, Davide; Miculan, Marino</p> <p></p> <p>We present DBtk, a toolkit for <span class="hlt">Directed</span> Bigraphs. DBtk supports a textual language for <span class="hlt">directed</span> bigraphs, the graphical visualization of bigraphs, the calculation of IPO labels, and the calculation of redex matchings. Therefore, this toolkit provides the main functions needed to implement simulators and verification tools.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2013&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2013-title47-vol5/pdf/CFR-2013-title47-vol5-sec216-1.pdf"><span id="translatedtitle">47 CFR 216.1 - NCS <span class="hlt">Directives</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>...2013-10-01 2013-10-01 false NCS <span class="hlt">Directives</span>. 216.1 Section 216.1...COMMUNICATIONS SYSTEM ISSUANCE SYSTEM § 216.1 NCS <span class="hlt">Directives</span>. In accordance with § 202.3(c)(12)(v), the Manager, NCS, has developed a system of official...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2014&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2014-title47-vol5/pdf/CFR-2014-title47-vol5-sec216-1.pdf"><span id="translatedtitle">47 CFR 216.1 - NCS <span class="hlt">Directives</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-10-01</p> <p>...2014-10-01 2014-10-01 false NCS <span class="hlt">Directives</span>. 216.1 Section 216.1...COMMUNICATIONS SYSTEM ISSUANCE SYSTEM § 216.1 NCS <span class="hlt">Directives</span>. In accordance with § 202.3(c)(12)(v), the Manager, NCS, has developed a system of official...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2011&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2011-title47-vol5/pdf/CFR-2011-title47-vol5-sec216-1.pdf"><span id="translatedtitle">47 CFR 216.1 - NCS <span class="hlt">Directives</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>...2011-10-01 2011-10-01 false NCS <span class="hlt">Directives</span>. 216.1 Section 216.1...COMMUNICATIONS SYSTEM ISSUANCE SYSTEM § 216.1 NCS <span class="hlt">Directives</span>. In accordance with § 202.3(c)(12)(v), the Manager, NCS, has developed a system of official...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2012&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2012-title47-vol5/pdf/CFR-2012-title47-vol5-sec216-1.pdf"><span id="translatedtitle">47 CFR 216.1 - NCS <span class="hlt">Directives</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-10-01</p> <p>...2012-10-01 2012-10-01 false NCS <span class="hlt">Directives</span>. 216.1 Section 216.1...COMMUNICATIONS SYSTEM ISSUANCE SYSTEM § 216.1 NCS <span class="hlt">Directives</span>. In accordance with § 202.3(c)(12)(v), the Manager, NCS, has developed a system of official...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/50032977"><span id="translatedtitle">A soft switched <span class="hlt">direct</span> frequency changer</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>M. V. M. Villaca; Amaldo J. Perin</p> <p>1995-01-01</p> <p>Development in power semiconductors and commutation techniques has brought back the interest in <span class="hlt">direct</span> frequency changers. A soft switched three-phase to single-phase <span class="hlt">direct</span> frequency changer is introduced adopting the bidirectional ZVS cell proposed by the authors (see IEEE APEC, 1995). Hence, the proposed converter does not need dead time between gate signals, presents natural protection against overcurrent, uses a simple</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/26821315"><span id="translatedtitle"><span class="hlt">Direction</span> of arrival measurements at UHF</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>P. A. Matthews; B. Mohebbi</p> <p>1989-01-01</p> <p><span class="hlt">Direction</span> of arrival measurements have been made at 870 MHz using land mobile radio systems in an urban environment. Examples are given showing the multipath components arriving at the receiver after reflection and scattering from buildings. A synthetic aperture technique is used to measure the <span class="hlt">directions</span> of arrival.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.math.rutgers.edu/~sontag/FTP_DIR/05cdc-papers-refs-eds/3040.pdf"><span id="translatedtitle"><span class="hlt">Directional</span> migration: a prototypical cellular control system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Sontag, Eduardo</p> <p></p> <p><span class="hlt">Directional</span> migration: a prototypical cellular control system Pablo A. Iglesias Electrical-studied forms of cellular function: <span class="hlt">directed</span> cell migration. Chemotaxis is the movement of cells guided infection. There are cells which, though normally stationary, can also migrate in response to external cues</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=ERIC&redirectUrl=http://eric.ed.gov/?q=DSC&pg=3&id=ED163704"><span id="translatedtitle">Replicating <span class="hlt">Direction</span> Service: A Hand Book.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Drake Univ., Des Moines, IA. Midwest Regional Resource Center.</p> <p></p> <p>The handbook details planning and development of a <span class="hlt">direction</span> service center (DSC), an agency which matches the needs of handicapped persons with appropriate services. A replication sequence, based upon practices of the Jackson County, Missouri, <span class="hlt">Direction</span> Service Center, is discussed for the following six areas: development of a resource…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/49114858"><span id="translatedtitle">Ascertaining <span class="hlt">directionality</span> information from incident nuclear radiation</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Brian C. Archambault; Joseph R. Lapinskas; Jing Wang; Jeffrey A. Webster; Sean McDeavitt; Rusi P. Taleyarkhan</p> <p>2011-01-01</p> <p>Unprecedented capabilities for the detection of nuclear particles via tailored resonant acoustic systems such as the acoustic tensioned metastable fluid detection (ATMFD) systems were assessed for determining <span class="hlt">directionality</span> of incoming fast neutrons. This paper presents advancements that expand on these accomplishments, thereby increasing the accuracy and precision of ascertaining <span class="hlt">directionality</span> information utilizing enhanced signal processing-cum-signal analysis, refined computational algorithms, and</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/31443686"><span id="translatedtitle"><span class="hlt">Direct</span> light transmittance through ceramic brackets</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Theodore Eliades; William M. Johnston; George Eliades</p> <p>1995-01-01</p> <p>The objective of this study was to investigate the degree of <span class="hlt">direct</span> light transmittance (%T) of various types of esthetic brackets and to correlate these values with their structure, morphologic factors, and composition. Eight types of brackets were used in the study; six brackets of each type were tested. An ultraviolet-visible spectroscopic <span class="hlt">direct</span> transmission analysis was performed at 320 to</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.ece.umn.edu/users/hjacobs/publications/2006NanoLetters-Barry.pdf"><span id="translatedtitle">Fringing Field <span class="hlt">Directed</span> Assembly of Nanomaterials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Jacobs, Heiko O.</p> <p></p> <p>Fringing Field <span class="hlt">Directed</span> Assembly of Nanomaterials Chad R. Barry and Heiko O. Jacobs* Department on a new gas-phase printing approach to deposit nanomaterials into addressable areas on a surface with 50 and SiO2) with openings to a silicon substrate are used to <span class="hlt">direct</span> the assembly of nanomaterials</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/35335148"><span id="translatedtitle">Optimization of <span class="hlt">direct</span> cell counting in sediment</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Heidi L Gough; David A Stahl</p> <p>2003-01-01</p> <p>This study reports a method for optimizing <span class="hlt">direct</span> counts of bacteria in sediment, designed to reduce the masking by sediment particles. The protocol was designed to determine appropriate dilution factors by incorporating counting statistics and was used to measure depth-associated changes in microbial abundance in metal-impacted freshwater sediments. We demonstrated a <span class="hlt">direct</span> method to determine appropriate sample dilution for accurate</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASAADS&redirectUrl=http://adsabs.harvard.edu/abs/2014APS..MAR.F3010X"><span id="translatedtitle">Microwave <span class="hlt">Directional</span> Coupler for Quantum Measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Victoria; Macklin, Chris; Eddins, Andrew; Siddiqi, Irfan</p> <p>2014-03-01</p> <p>We present the design of a 20dB single-section <span class="hlt">directional</span> coupler using two edge-coupled, conductor-backed coplanar waveguides (CPW). We begin with an electromagnetic analysis of the physical mechanisms that allow two waveguides to form a <span class="hlt">directional</span> coupler. Based on the coplanar waveguide geometry used for the coupler, we experienced inherently limited <span class="hlt">directivity</span> in the performance, and we discuss the mechanisms by which we optimize for <span class="hlt">directivity</span> despite geometric limitations. After laying out the theory behind CPW <span class="hlt">directional</span> couplers, an electromagnetic analysis of our simulated design is presented. Two iterations of designs were fabricated. The final <span class="hlt">directional</span> coupler yields simulated and measured performance even beyond the level of our design goals. At the center frequency of 6 GHz, our coupler showed comparable performance to commercial <span class="hlt">directional</span> couplers. The 20-dB <span class="hlt">directional</span> coupler serves as a solid-state equivalent of a 99/1 beam splitter for microwave photons, and will further enable on-chip experiments in quantum measurement. This work was funded by National Science Foundation Award ECCS-0939514.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.math.tau.ac.il/~krivelev/outbranch.ps"><span id="translatedtitle">Parameterized Algorithms for <span class="hlt">Directed</span> Maximum Leaf Problems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Krivelevich, Michael</p> <p></p> <p>Parameterized Algorithms for <span class="hlt">Directed</span> Maximum Leaf Problems Noga Alon 1 , Fedor V. Fomin 2 spanning tree, then D contains one with at least (n/2) 1/5 - 1 leaves. 1 Introduction The Maximum Leaf a digraph D, the <span class="hlt">Directed</span> Maximum Leaf Out­Branching problem is the problem of finding an out­branching in D</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950012718&hterms=drug+abuse&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddrug%2Babuse"><span id="translatedtitle">NASA <span class="hlt">directives</span>: Master list and index</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p>This Handbook sets forth in two parts the following information for the guidance of users of the NASA Management <span class="hlt">Directives</span> System. Chapter 1 contains introductory information material on how to use this Handbook. Chapter 2 is a complete master list of Agency-wide management <span class="hlt">directives</span>, describing each <span class="hlt">directive</span> by type, number, effective date, expiration date, title, and organization code of the office responsible for the <span class="hlt">directive</span>. Chapter 3 includes a consolidated numerical list of all delegations of authority and a breakdown of such delegation by the office of Installation to which special authority is assigned. Chapter 4 sets forth a consolidated list of all NASA Handbooks (NHB's) and important footnotes covering the control and ordering of such documents. Chapter 5 is a consolidated list of NASA management <span class="hlt">directives</span> applicable to the Jet Propulsion Laboratory. Chapter 6 is a consolidated list of NASA management <span class="hlt">directives</span> published in the code of Federal Regulations. Complementary manuals to the NASA Management <span class="hlt">Directives</span> System are described in Chapter 7. Part B contains an in-depth alphabetical index to all NASA management <span class="hlt">directives</span> other than Handbooks.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.math.utk.edu/~schulze/paper3.pdf"><span id="translatedtitle">of Flow on Morphological Stability <span class="hlt">Directional</span> Solidification</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Schulze, Tim</p> <p></p> <p>Effects During of Flow on Morphological Stability <span class="hlt">Directional</span> Solidification S.H. DAVIS and T.P. SCHULZE Research involving the interaction of flow with morphological instability during <span class="hlt">directional</span> solidifi- cation of binary alloys is reviewed. In general, flow may arise during the solidification process</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/51917993"><span id="translatedtitle">Satellite <span class="hlt">direct</span> readout: Opportunities for science education</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Thomas W. Wagner</p> <p>1994-01-01</p> <p>This report describes the technology associated with <span class="hlt">direct</span> reception and analysis of environmental (weather) satellite data and the opportunities it offers to educators for enhancing mathematics, science, and technology education in the United States. With newly available capabilities, <span class="hlt">direct</span> readout is applicable to a wide range of environmental assessments, information networking, and modelling applications, in addition to the learning opportunities</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=PMC&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4145420"><span id="translatedtitle"><span class="hlt">Direct</span> oral anticoagulants: integration into clinical practice</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cowell, Richard P W</p> <p>2014-01-01</p> <p>The introduction of <span class="hlt">direct</span> oral anticoagulants (OACs) for the treatment and prevention of thromboembolic disease represents a shift from the traditional vitamin K antagonist-based therapies, which have been the mainstay of treatment for almost 60?years. A challenge for hospital formularies will be to manage the use of <span class="hlt">direct</span> OACs from hospital to outpatient settings. Three <span class="hlt">direct</span> OACs—apixaban, dabigatran and rivaroxaban—are widely approved across different indications, with rivaroxaban approved across the widest breadth of indications. A fourth <span class="hlt">direct</span> OAC, edoxaban, has also completed phase III trials. Implementation of these agents by physicians will require an understanding of the efficacy and safety profile of these drugs, as well as an awareness of renal function, comedication use, patient adherence and compliance. Optimal implementation of <span class="hlt">direct</span> OACs in the hospital setting will provide improved patient outcomes when compared with traditional anticoagulants and will simplify the treatment and prevention of thromboembolic diseases. PMID:25012514</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19940010941&hterms=indexed&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dindexed"><span id="translatedtitle">NASA <span class="hlt">directives</span> master list and index</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1993-01-01</p> <p>This Handbook sets forth in two parts the following information for the guidance of users of the NASA Management <span class="hlt">Directives</span> System. Part A is a master list of management <span class="hlt">directives</span> in force as of March 31, 1993. Chapter 1 contains introductory informative material on how to use this Handbook. Chapter 2 is a complete master list of Agencywide management <span class="hlt">directives</span>, describing each <span class="hlt">directive</span> by type, number, effective date, expiration date, title, and organization code of the office responsible for the <span class="hlt">directive</span>. Chapter 3 includes a consolidated numerical list of all delegations of authority and a breakdown of such delegation by the office or installation to which special authority is assigned. Chapter 4 sets forth a consolidated list of all NASA Handbooks (NHB's) and important footnotes covering the control and ordering of such documents. Chapter 5 is a consolidated list of NASA management <span class="hlt">directives</span> applicable to the Jet Propulsion Laboratory. Chapter 6 is a consolidated list of NASA management <span class="hlt">directives</span> published in the Code of Federal Regulations. Complementary manuals to the NASA Management <span class="hlt">Directives</span> System are described in Chapter 7. Part B is the index to NASA management <span class="hlt">directives</span> in force as of March 31, 1993. This part contains an in-depth alphabetical index to all NASA management <span class="hlt">directives</span> other than Handbooks. NHB's 1610.6, 'NASA Personnel Security Handbook,' 1620.3, 'NASA Physical Security Handbook,' 1640.4, 'NASA Information Security Program,' 1900.1, 'Standards of Conduct for NASA Employees,' 5103.6, 'Source Evaluation Board Handbook,' and 7400.1, 'Budget Administration Manual,' are indexed in-depth. All other NHB's are indexed by titles only.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://hal.archives-ouvertes.fr/docs/00/19/73/59/PDF/Veermans-Koen-2000.pdf"><span id="translatedtitle">Promoting Self <span class="hlt">Directed</span> Learning 1 Running head: PROMOTING SELF <span class="hlt">DIRECTED</span> LEARNING</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Paris-Sud XI, Université de</p> <p></p> <p>for discovery learning based on an "opportunistic" learning model that takes the current hypothesis <span class="hlt">Directed</span> Learning in Simulation Based Discovery Learning Environments through Intelligent Support Koen-<span class="hlt">Directed</span> Learning in Simulation Based Discovery Learning Environments Through Intelligent Support. Interactive</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/797148"><span id="translatedtitle"><span class="hlt">Direct</span>-Sequence Spread-Spectrum Using <span class="hlt">Directionally</span> Constrained Adaptive Beam Forming to Null Interference</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Mark A. Jones; Mark A. Wickert</p> <p>1995-01-01</p> <p>A <span class="hlt">direct</span>-sequence spread-spectrum communication system using an adaptive antenna array to null interference is examined. The system model is a modification of Compton's (1978) system, using a digital implementation and a <span class="hlt">directional</span> constraint. Computer simulations are used to compare the behavior of the <span class="hlt">directionally</span> constrained model with Compton's model with emphasis on spread-spectrum code synchronization. In the <span class="hlt">directed</span> system, nulling</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.utwente.nl/ub/pics/sciencedirect_iphone_userguide.pdf"><span id="translatedtitle">SciVerse Science<span class="hlt">Direct</span> SciVerse Science<span class="hlt">Direct</span> iPhone app</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Twente, Universiteit</p> <p></p> <p>SciVerse Science<span class="hlt">Direct</span> SciVerse Science<span class="hlt">Direct</span> iPhone app User Guide December 2010 Open;Welcome to the SciVerse Science<span class="hlt">Direct</span> iPhone app: How to use this step-by-step guide The SciVerse Science<span class="hlt">Direct</span> iPhone app connects users to a leading full-text scientific database offering journal articles</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://hdl.handle.net/2060/20080004941"><span id="translatedtitle">Weld repair of <span class="hlt">directionally</span> solidified articles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)</p> <p>2002-01-01</p> <p>A <span class="hlt">directionally</span> solidified nickel-base superalloy article has a defect therein extending parallel to the solidification <span class="hlt">direction</span>. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the <span class="hlt">directionally</span> solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a <span class="hlt">direction</span> parallel to the solidification <span class="hlt">direction</span>. Optionally, additional artificial heat extraction is accomplished in a heat-flow <span class="hlt">direction</span> that is within about 45 degrees of the solidification <span class="hlt">direction</span>, as the filler metal solidifies within the defect. The article may thereafter be heat treated.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://hdl.handle.net/2060/20080007464"><span id="translatedtitle"><span class="hlt">Directionally</span> solidified article with weld repair</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)</p> <p>2003-01-01</p> <p>A <span class="hlt">directionally</span> solidified nickel-base superalloy article has a defect therein extending parallel to the solidification <span class="hlt">direction</span>. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the <span class="hlt">directionally</span> solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a <span class="hlt">direction</span> parallel to the solidification <span class="hlt">direction</span>. Optionally, additional artificial heat extraction is accomplished in a heat-flow <span class="hlt">direction</span> that is within about 45 degrees of the solidification <span class="hlt">direction</span>, as the filler metal solidifies within the defect. The article may thereafter be heat treated.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://managers.hr.columbia.edu/files_hrmanagertoolkit/imce_shared/Direct_Deposit_Instructions_03_2012.pdf"><span id="translatedtitle"><span class="hlt">Direct</span> Deposit _Job Aid March 2012 Page 1 of 7 <span class="hlt">Direct</span> Deposit Online Instructions Job Aid</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Grishok, Alla</p> <p></p> <p>the "Add Account" box to add your bank information. Babs Bunny Babs Bunny #12;<span class="hlt">Direct</span> Deposit _Job Aid March entry is complete. Babs Bunny #12;<span class="hlt">Direct</span> Deposit _Job Aid March 2012 Page 5 of 7 STEP . . . ACTION nd account. You successfully entered your <span class="hlt">direct</span> deposit information. Babs Bunny Babs Bunny #12</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=ERIC&redirectUrl=http://eric.ed.gov/?q=self-focusing&pg=3&id=EJ362011"><span id="translatedtitle">Self-<span class="hlt">Directed</span> and Distance Learning: Facilitating Self-<span class="hlt">Directed</span> Learning beyond the Instititutional Setting.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Garrison, D. Randy</p> <p>1987-01-01</p> <p>Analyzes the concept of self-<span class="hlt">directed</span> learning, focusing on the facilitation of self-<span class="hlt">directed</span> learning in the noninstitutional setting. Clarifies self-<span class="hlt">directed</span> learning and follows with an outline and discussion of the ability of distance education to facilitate such learning. (CH)</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/336779"><span id="translatedtitle">Multi-<span class="hlt">directional</span> search: A <span class="hlt">direct</span> search algorithm for parallel machines</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Virginia Joanne Torczon</p> <p>1989-01-01</p> <p>In recent years there has been a great deal in the development of optimization algorithms which exploit the computational power of parallel computer architectures. The author has developed a new <span class="hlt">direct</span> search algorithm, which he calls multi-<span class="hlt">directional</span> search, that is ideally suited for parallel computation. His algorithm belongs to the class of <span class="hlt">direct</span> search methods, a class of optimization algorithms</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890013457&hterms=edgetone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dedgetone"><span id="translatedtitle"><span class="hlt">Direct</span> simulation of compressible reacting flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Poinsot, Thierry J.</p> <p>1989-01-01</p> <p>A research program for <span class="hlt">direct</span> numerical simulations of compressible reacting flows is described. Two main research subjects are proposed: the effect of pressure waves on turbulent combustion and the use of <span class="hlt">direct</span> simulation methods to validate flamelet models for turbulent combustion. The interest of a compressible code to study turbulent combustion is emphasized through examples of reacting shear layer and combustion instabilities studies. The choice of experimental data to compare with <span class="hlt">direct</span> simulation results is discussed. A tentative program is given and the computation cases to use are described as well as the code validation runs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-MAS&redirectUrl=http://academic.research.microsoft.com/Publication/4432669"><span id="translatedtitle">Fast <span class="hlt">Directional</span> Continuous Spherical Wavelet Transform Algorithms</span></a></p> <p><a target="_blank" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p>Jason D. Mcewen; Michael P. Hobson; Daniel J. Mortlock; Anthony N. Lasenby</p> <p>2007-01-01</p> <p>Abstract—We,describe the construction,of a spherical wavelet analysis,through,the,inverse,stereographic,projection,of the Euclidean planar wavelet framework, introduced originally by Antoine and,Venderghynest,and,developed,further,by Wiaux et al.. Fast algorithms,for performing,the <span class="hlt">directional</span> continuous wavelet,analysis,on the,unit sphere,are presented. The fast <span class="hlt">directional</span> algorithm, based on the fast spherical convolution algorithm developed by Wandelt and G´orski, provides a saving of O( p N pix) over a <span class="hlt">direct</span> quadrature,implementation,for Npix pixels on</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NSDL&redirectUrl=http://www.classzone.com/books/earth_science/terc/content/visualizations/es2402/es2402page01.cfm?chapter_no=visualization"><span id="translatedtitle">Observe how the monsoon changes <span class="hlt">direction</span></span></a></p> <p><a target="_blank" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p>TERC. Center for Earth and Space Science Education</p> <p>2003-01-01</p> <p>This Earth science animation shows high school students how changes in wind speed and <span class="hlt">direction</span> are associated with the Asian monsoon. The introduction explains how seasonal movement of air pressure belts cause winds to change <span class="hlt">direction</span>. The animation uses a map to present the average April to December precipitation in Asia during the years 1985-1989. Color-enhancement indicates precipitation, and wind speed and <span class="hlt">direction</span> are designated by arrows. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=SCIGOV-STC&redirectUrl=http://www.osti.gov/scitech/servlets/purl/5286846"><span id="translatedtitle">Progress in <span class="hlt">direct</span> heat applications projects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Childs, F.W.; Jones, K.W.; Nelson, L.B.; Strawn, J.A.; Tucker, M.K.</p> <p>1980-09-09</p> <p>The development of hydrothermal energy for <span class="hlt">direct</span> heat applications is being aided by twenty-two demonstration projects that are funded on a cost-sharing basis by the US Department of Energy, Division of Geothermal Energy. These projects are designed to demonstrate the technical and economic feasibility of the <span class="hlt">direct</span> use of geothermal heat in the United States. Twelve of these projects are administered by the DOE-Idaho Operations Office with technical support from EG and G Idaho, Inc. Engineering and economic data for these projects are summarized in this paper. The data and experience being generated by these projects will be an important basis for future geothermal <span class="hlt">direct</span> use projects.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=PUBMED&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/18406116"><span id="translatedtitle"><span class="hlt">Direct</span> compression properties of chitin and chitosan.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mir, Viviana García; Heinämäki, Jyrki; Antikainen, Osmo; Revoredo, Ofelia Bilbao; Colarte, Antonio Iraizoz; Nieto, Olga Maria; Yliruusi, Jouko</p> <p>2008-08-01</p> <p>Deformation and compaction properties of native amino poly-saccharides chitin and chitosan were studied and compared with those obtained with established pharmaceutical <span class="hlt">direct</span> compression excipients. An instrumented single-punch tablet machine was used for tablet compaction. The following compression parameters were evaluated: a ratio of crushing strength and compression pressure, plasticity and elasticity factor (PF and EF), tensile strength and R-value. Chitin and chitosan were found to have a marked tendency to plastic deformation, and both showed a good compression behaviour compared with the other <span class="hlt">direct</span> compression excipients including microcrystalline cellulose. It is concluded that chitin and chitosan are potential co-excipients for <span class="hlt">direct</span> compression applications. PMID:18406116</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASA-TRS&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19880055943&hterms=directional+solidified&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddirectional%2Bsolidified"><span id="translatedtitle">Characterization of <span class="hlt">directionally</span> solidified lead chloride</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Singh, Narsingh Bahadur; Duval, W. M. B.; Rosenthal, B. N.</p> <p>1988-01-01</p> <p>A <span class="hlt">directionally</span> solidified PbCl2 material was prepared and analyzed and subsequently used to grow single crystals. It was found that silicon, halogens, sulfur, magnesium, and phosphorus were the hardest impurities to remove by the single-pass <span class="hlt">directional</span> freezing. Single crystals grown from the purified material displayed good scattering beam quality and showed no absorption peaks between 0.30 to 20 microns. <span class="hlt">Direct</span> photographic observations of the solid-liquid interface at several G/V (denoting the temperature gradient and the translation velocity, respectively) ratio values showed that, as the G/V ratio decreased, the interface varied from a smooth convex surface to dendritic.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=PUBMED&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/18370390"><span id="translatedtitle">Electrocatalytic performance of fuel oxidation by Pt3Ti nanoparticles.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abe, Hideki; Matsumoto, Futoshi; Alden, Laif R; Warren, Scott C; Abruña, Héctor D; DiSalvo, Francis J</p> <p>2008-04-23</p> <p>A Pt-based electrocatalyst for <span class="hlt">direct</span> fuel cells, Pt3Ti, has been prepared in the form of nanoparticles. Pt(1,5-cyclooctadiene)Cl2 and Ti(tetrahydrofuran)2Cl4 are reduced by sodium naphthalide in tetrahydrofuran to form atomically disordered Pt3Ti nanoparticles (FCC-type structure: Fm3m; a = 0.39 nm; particle size = 3 +/- 0.4 nm). These atomically disordered Pt3Ti nanoparticles are transformed to larger atomically ordered Pt3Ti nanoparticles (Cu3Au-type structure: Pm3m; a = 0.3898 nm; particle size = 37 +/- 23 nm) by annealing above 400 degrees C. Both atomically disordered and ordered Pt3Ti nanoparticles show lower onset potentials for the oxidation of formic acid and methanol than either pure Pt or <span class="hlt">Pt-Ru</span> nanoparticles. Both atomically disordered and ordered Pt3Ti nanoparticles show a much lower affinity for CO adsorption than either pure Pt or <span class="hlt">Pt-Ru</span> nanoparticles. Atomically ordered Pt3Ti nanoparticles show higher oxidation current densities for both formic acid and methanol than pure Pt, <span class="hlt">Pt-Ru</span>, or atomically disordered Pt3Ti nanoparticles. Pt3Ti nanoparticles, in particular the atomically ordered materials, have promise as anode catalysts for <span class="hlt">direct</span> fuel cells. PMID:18370390</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2010-title12-vol1/pdf/CFR-2010-title12-vol1-sec3-19.pdf"><span id="translatedtitle">12 CFR 3.19 - Issuance of a <span class="hlt">directive</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 3.19 Section 3.19 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY MINIMUM CAPITAL RATIOS; ISSUANCE OF <span class="hlt">DIRECTIVES</span> Issuance of a <span class="hlt">Directive</span> § 3.19 Issuance of a <span class="hlt">directive</span>. (a) A <span class="hlt">directive</span> will be...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2012&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2012-title19-vol1/pdf/CFR-2012-title19-vol1-sec10-193.pdf"><span id="translatedtitle">19 CFR 10.193 - Imported <span class="hlt">directly</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-04-01</p> <p>...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Caribbean Basin Initiative § 10.193 Imported <span class="hlt">directly</span>. To qualify for treatment under the CBI, an article shall be...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2010-title19-vol1/pdf/CFR-2010-title19-vol1-sec10-193.pdf"><span id="translatedtitle">19 CFR 10.193 - Imported <span class="hlt">directly</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Caribbean Basin Initiative § 10.193 Imported <span class="hlt">directly</span>. To qualify for treatment under the CBI, an article shall be...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=CFR2011&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2011-title19-vol1/pdf/CFR-2011-title19-vol1-sec10-193.pdf"><span id="translatedtitle">19 CFR 10.193 - Imported <span class="hlt">directly</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-04-01</p> <p>...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Caribbean Basin Initiative § 10.193 Imported <span class="hlt">directly</span>. To qualify for treatment under the CBI, an article shall be...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=PMC&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3817516"><span id="translatedtitle">An easy <span class="hlt">direct</span> arylation of 5-pyrazolones</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gong, Hao; Yang, Yiwen; Wang, Zechao</p> <p>2013-01-01</p> <p>Summary A mild, efficient and catalytic ligand-free method for the <span class="hlt">direct</span> arylation of 5-pyrazolones by Pd-catalyzed C–H bond activation is reported. The process smoothly proceeds and yields are moderate to excellent. PMID:24204415</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://www.optimization-online.org/DB_FILE/2010/06/2639.pdf"><span id="translatedtitle">Worst Case Complexity of <span class="hlt">Direct</span> Search</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p></p> <p>2010-05-13</p> <p>May 13, 2010 ... and using a framework of the type of GSS (generating set search). ... of pattern search, generalized pattern search (GPS), mesh adaptive <span class="hlt">direct</span> ... of the behavior of the step size parameter ?k which must approach zero as.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://kuscholarworks.ku.edu/handle/1808/16360"><span id="translatedtitle">Ownership Structure in Foreign <span class="hlt">Direct</span> Investment Projects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Asiedu, Elizabeth; Esfahani, Hadi Salehi</p> <p>2001-03-13</p> <p>This paper theoretically and empirically examines ownership structure in foreign <span class="hlt">direct</span> investment (FDI) projects. We show that in choosing an ownership structure, foreign investors, local entrepreneurs, and government consider the specific, costly...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=ERIC&redirectUrl=http://eric.ed.gov/?q=foreign+AND+direct+AND+investments&pg=2&id=EJ353184"><span id="translatedtitle"><span class="hlt">Direct</span> Foreign Investment in the United Kingdom.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Hinde, Kevin</p> <p>1987-01-01</p> <p>Notes introductory undergraduate economics textbooks have no formal analysis of the rationale for <span class="hlt">direct</span> foreign investment by multinational firms. Examines this area in an attempt to develop more content information for undergraduate courses. (RKM)</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPA-EIMS&redirectUrl=http://oaspub.epa.gov/eims/eimsapi.dispdetail?deid=246411"><span id="translatedtitle">Spatially Refined Aerosol <span class="hlt">Direct</span> Radiative Focusing Efficiencies</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Global aerosol <span class="hlt">direct</span> radiative forcing (DRF) is an important metric for assessing potential climate impacts of future emissions changes. However, the radiative consequences of emissions perturbations are not readily quantified nor well understood at the level of detail necessary...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NSDL&redirectUrl=http://www.sciencemag.org/cgi/content/full/sci;324/5925/346?maxtoshow=&hits=10&RESULTFORMAT=&searchid=1&FIRSTINDEX=30&resourcetype=HWCIT"><span id="translatedtitle">CELL BIOLOGY: Two Lipids That Give <span class="hlt">Direction</span></span></a></p> <p><a target="_blank" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p>Jean-François Côté (Université de Montréal; Institut de Recherches Cliniques de Montréal)</p> <p>2009-04-17</p> <p>Access to the article is free, however registration and sign-in are required. Precise and sequential intracellular signaling events involving two phospholipids <span class="hlt">direct</span> an immune cell toward an attractant molecule gradient.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NASAADS&redirectUrl=http://adsabs.harvard.edu/abs/1991STIN...9224030L"><span id="translatedtitle">Geothermal <span class="hlt">direct</span> use engineering and design guidebook</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lienau, P. J.; Lunis, B. C.</p> <p>1991-09-01</p> <p>The Geothermal <span class="hlt">Direct</span> Use Engineering and Design Guidebook is designed to be a comprehensive, thoroughly practical reference guide for engineers and designers of <span class="hlt">direct</span> heat projects. These projects could include the conversion of geothermal energy into space heating and cooling of buildings, district heating, greenhouse heating, aquaculture and industrial processing. The Guidebook is <span class="hlt">directed</span> at understanding the nature of geothermal resources and the exploration of the resources, fluid sampling techniques, drilling, and completion of geothermal wells through well testing, and reservoir evaluation. It presents information useful to engineers on the specification of equipment including well pumps, piping, heat exchangers, space heating equipment, heat pumps and absorption refrigeration. A compilation of current information about greenhouse aquaculture and industrial applications is included together with a discussion of engineering cost analysis, regulation requirements, and environmental consideration. The purpose of the Guidebook is to provide an integrated view for the development of <span class="hlt">direct</span> use projects for which there is a very large potential in the United States.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://arxiv.org/pdf/1110.0718.pdf"><span id="translatedtitle"><span class="hlt">Directed</span> information and Pearl's causal calculus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Raginsky, Maxim</p> <p>2011-01-01</p> <p>Probabilistic graphical models are a fundamental tool in statistics, machine learning, signal processing, and control. When such a model is defined on a <span class="hlt">directed</span> acyclic graph (DAG), one can assign a partial ordering to the events occurring in the corresponding stochastic system. Based on the work of Judea Pearl and others, these DAG-based "causal factorizations" of joint probability measures have been used for characterization and inference of functional dependencies (causal links). This mostly expository paper focuses on several connections between Pearl's formalism (and in particular his notion of "intervention") and information-theoretic notions of causality and feedback (such as causal conditioning, <span class="hlt">directed</span> stochastic kernels, and <span class="hlt">directed</span> information). As an application, we show how conditional <span class="hlt">directed</span> information can be used to develop an information-theoretic version of Pearl's "back-door" criterion for identifiability of causal effects from passive observations. This suggests that the back-door cri...</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=NSDL&redirectUrl=http://onramp.nsdl.org/eserv/onramp:18323/Nonfiction_Cafe_Directions.pdf"><span id="translatedtitle">Differentiating at the Nonfiction Cafe Menu: <span class="hlt">Directions</span></span></a></p> <p><a target="_blank" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p>Tracey Allen</p> <p></p> <p>This PDF provides <span class="hlt">directions</span> for copying and folding the Nonfiction Cafe Menu. The menu provides a set of post-reading activities from which students may choose, creating a differentiated instruction experience.</p> </li> <li> <p><a target="resultTitleLink" href="http://www.science.gov/scigov/desktop/en/ostiblue/service/link/track?type=RESULT&searchId=topic-pages&collectionCode=EPRINT&redirectUrl=http://dspace.mit.edu/handle/1721.1/89104"><span id="translatedtitle"><span class="hlt">Direct</span> transfer of graphene onto flexible substrates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p>Araujo, P. T.</p> <p></p> <p>In this paper we explore the <span class="hlt">direct</span> transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. 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