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1

Structural analysis of sonochemically prepared PtRu versus Johnson Matthey PtRu in operating direct methanol fuel cells  

Microsoft Academic Search

Sonochemically prepared PtRu (3 : 1) and Johnson Matthey PtRu (1 : 1) were analyzed by X-ray absorption spectroscopy in operating liquid feed direct methanol fuel cells. The total metal loadings were 4 mg cm⁻² unsupported catalysts at the anode and cathode of the membrane electrode assembly. Ex situ XRD lattice parameter analysis indicates partial segregation of the Ru from

Stanislav Stoupin; Harry Rivera; Zhengrong Li; Carlo U. Segre; Carol Korzeniewski; Dominick J. Casadonte Jr.; Hisashi Inoue; Eugene S. Smotkin

2008-01-01

2

Structural analysis of sonochemically prepared PtRu versus Johnson Matthey PtRu in operating direct methanol fuel cells  

SciTech Connect

Sonochemically prepared PtRu (3 : 1) and Johnson Matthey PtRu (1 : 1) were analyzed by X-ray absorption spectroscopy in operating liquid feed direct methanol fuel cells. The total metal loadings were 4 mg cm{sup -2} unsupported catalysts at the anode and cathode of the membrane electrode assembly. Ex situ XRD lattice parameter analysis indicates partial segregation of the Ru from the PtRu fcc alloy in both catalysts. A comparison of the in situ DMFC EXAFS to that of the as-received catalyst shows that catalyst restructuring during DMFC operation increases the total metal coordination numbers. A combined analysis of XRD determined grain sizes and lattice parameters, ex situ and in situ EXAFS analysis, and XRF of the as-received catalysts enables determination of the catalyst shell composition. The multi-spectrum analysis shows that the core size increases during DMFC operation by reduction of Pt oxides and incorporation of Pt into the core. This increases the mole fraction of Ru in the catalyst shell structure.

Stoupin, Stanislav; Rivera, Harry; Li, Zhengrong; Segre, Carlo U.; Korzeniewski, Carol; Casadonte, Jr., Dominick J.; Inoue, Hisashi; Smotkin, Eugene S. (IIT); (Puerto Rico); (TTU); (Rigaku); (NEU)

2009-01-15

3

Stability and durability of PtRu catalysts supported on carbon nanofibers for direct methanol fuel cells  

Microsoft Academic Search

The chemical stability and durability of PtRu catalysts supported on carbon nanofibers (CNFs) for the anode electrode of a direct methanol fuel cell (DMFC) are investigated by Pt and Ru dissolution tests in sulfuric acid and long-term performance tests of a single cell discharging at a constant current density of 150mAcm?2 for approximately 2000h. A CNF with a herringbone-type structure,

Segoo Kang; Seongyop Lim; Dong-Hyun Peck; Sang-Kyung Kim; Doo-Hwan Jung; Seong-Hwa Hong; Han-Gi Jung; Yonggun Shul

4

Atomistic modeling of the directed-assembly of bimetallic Pt-Ru nanoclusters on Ru(0001)-supported monolayer graphene  

NASA Astrophysics Data System (ADS)

The formation of Pt-Ru nanoclusters (NCs) by sequential deposition of Pt and Ru on a periodically rumpled graphene sheet supported on Ru(0001) is analyzed by atomistic-level modeling and kinetic Monte Carlo simulations. The ``coarse-scale'' periodic variation of the adsorption energy of metal adatoms across the graphene sheet directs the assembly of NCs to a periodic array of thermodynamically preferred locations. The modeling describes not only just the NC densities and size distributions, but also the composition distribution for mixed NCs. A strong dependence of these quantities on the deposition order is primarily related to different effective mobilities of Pt and Ru on the supported graphene.

Han, Yong; Engstfeld, Albert K.; Behm, R. Juergen; Evans, James W.

2013-04-01

5

Pt and Ru X-ray Absorption Spectroscopy of PtRu Anode Catalysts in Operating Direct Methanol Fuel Cells  

SciTech Connect

In situ X-ray absorption spectroscopy, ex situ X-ray fluorescence, and X-ray powder diffraction enabled detailed core analysis of phase segregated nanostructured PtRu anode catalysts in an operating direct methanol fuel cell (DMFC). No change in the core structures of the phase segregated catalyst was observed as the potential traversed the current onset potential of the DMFC. The methodology was exemplified using a Johnson Matthey unsupported PtRu (1:1) anode catalyst incorporated into a DMFC membrane electrode assembly. During DMFC operation the catalyst is essentially metallic with half of the Ru incorporated into a face-centered cubic (FCC) Pt alloy lattice and the remaining half in an amorphous phase. The extended X-ray absorption fine structure (EXAFS) analysis suggests that the FCC lattice is not fully disordered. The EXAFS indicates that the Ru-O bond lengths were significantly shorter than those reported for Ru-O of ruthenium oxides, suggesting that the phases in which the Ru resides in the catalysts are not similar to oxides.

Stoupin, S.; Chung, E-H.; Chattopadhyay, S.; Segre, C.U.; Smotkin, E.S. (IIT); (Puerto Rico)

2008-06-16

6

Hydrothermal synthesis of PtRu nanoparticles supported on graphene sheets for methanol oxidation in direct methanol fuel cell  

Microsoft Academic Search

Platinumruthenium (PtRu) nanoparticles are dispersed on graphene nanosheets and multi-walled carbon nanotubes (MWCNTs) via a hydrothermal method. Transmission electron microsocopy (TEM) observation shows the uniformly dispersed nanoparticles and the average nanoparticle size has been calculated. The electrochemical measurements demonstrate that the PtRu\\/graphene catalyst exhibits about two times higher mass activity and better tolerance to poisoning species in methanol electro-oxidation than

Seok Hee Lee; Nitul Kakati; Seung Hyun Jee; Jatindranath Maiti; Young-Soo Yoon

2011-01-01

7

Methane conversion on PtRu nanoparticles alloy supported on hydrothermal carbon  

Microsoft Academic Search

The catalytic activity of a novel nanoparticulate PtRu alloy supported on hydrothermal carbon for dry methane reforming and for the partial oxidation of methane was studied. Upon removal of the carbon support by calcination under air, a mixture of Pt0 and Ru oxide was obtained and their catalytic properties have been as well investigated for the same reactions. Characterization was

Juan Matos; Maibelin Rosales; Rezan Demir-Cakan; Mara Magdalena Titirici

2010-01-01

8

Performance of Dimethyl-ether Fuel Cells using Pt-Ru Catalyst  

NASA Astrophysics Data System (ADS)

Phenomena is presented whereby the performance of a dimethyl-ether fuel cell (DDFC) at 80C is much lower when Pt-Ru catalyst is used on the anode than when Pt catalyst is used, in contrast to the higher performance achieved using Pt-Ru catalyst over Pt catalyst in direct methanol fuel cells (DMFC). The DDFC performance achieved using Pt-Ru catalyst increases with temperature and exceeds that using Pt catalyst at temperatures of over 100C. After high temperature operation, the performance of DDFC using Pt-Ru catalyst at 80C is improved. By supplying sufficient steam before operation, the performance of DDFC using Pt-Ru catalyst at 80C is also found to improve. Before and during operation, more steam is needed for stable operation of the DDFC using Pt-Ru catalyst at 80C than using Pt catalyst.

Haraguchi, Tadao; Tsutsumi, Yasuyuki; Takagi, Hiroyuki; Tamegai, Naoaki; Yamashita, Susumu

9

Methanol oxidation catalysis and substructure of PtRu bimetallic nanoparticles  

Microsoft Academic Search

Catalytic material of PtRu nanoparticles supported on carbon (PtRu\\/C) for direct methanol fuel cells was synthesized by a polyol reduction method. Addition of phosphorus was effective for downsizing PtRu particles and improving their catalytic activity. The activity obtained was six times of that of a commercial catalysis. The samples were analyzed by techniques of X-ray absorption fine structure (XAFS) at

Hiroaki Nitani; Takashi Nakagawa; Hideo Daimon; Yukiko Kurobe; Takahiro Ono; Yusuke Honda; Akiko Koizumi; Satoshi Seino; Takao A. Yamamoto

2007-01-01

10

Enhancement in electro-oxidation of methanol over PtRu black catalyst through strong interaction with iron oxide nanocluster.  

PubMed

One of the major issues in direct methanol fuel cell research is to develop a new catalyst for methanol electro-oxidation reaction (MOR) with high activity and low cost. In this study, a new, simple, and economic way was introduced to improve the catalytic activity of commercial PtRu black catalyst for the MOR. A nanocomposite electrode was fabricated by mixing the PtRu catalyst with Fe(2)O(3) nanoclusters. When 10 wt % of the PtRu catalyst was replaced by the Fe(2)O(3) nanoclusters, mass activity (A/g(Pt)) increased by 80% compared to that of the pure PtRu catalyst. Specific activity of the mixed catalyst was 100% higher than that of the pure PtRu catalyst. The nanocomposite catalysts were also applied to single cells. Although the amount of the PtRu catalyst was reduced by 10 wt %, 10% higher potential was observed in the nanocomposite catalysts at a current density of 100 mA/cm(2). PMID:20504037

Jeon, Min Ku; Lee, Ki Rak; Woo, Seong Ihl

2010-11-01

11

Alcohol Electrooxidation at Pt-Ru Sputter-deposited Electrode  

NASA Astrophysics Data System (ADS)

The use of various alcohols including methanol has been considered as the fuel of direct alcohol fuel cells (DAFCs). Thus far, the Pt alloys have mainly been studied as anode electrocatalysts for DAFCs. Pt itself is poisoned by chemical species produced during the alcohol oxidation. There exist many reports that the addition of Ru is effective for the alcohol oxidation. In this work, we prepared Pt-Ru co-sputtered electrode by changing Ru content, sputtering time and Ar pressure for the sputtering. By using the prepared electrocatalysts, relationships between sputtering conditions and electrocatalytic activity were measured for some alcohols.

Shibamine, Masahiko; Yamada, Akifumi; Umeda, Minoru; Tanaka, Shohji

12

Multifunctional Nanoparticulate Polyelectrolyte Complexes  

Microsoft Academic Search

Water-soluble, biodegradable, polymeric, polyelectrolyte complex dispersions (PECs) have evolved because of the limitations,\\u000a in terms of toxicity, of the currently available systems. These aqueous nanoparticulate architectures offer a significant\\u000a advantage for products that may be used as drug delivery systems in humans. PECs are created by mixing oppositely charged\\u000a polyions. Their hydrodynamic diameter, surface charge, and polydispersity are highly dependent

Sean M. Hartig; Rachel R. Greene; Mikhail M. Dikov; Ales Prokop; Jeffrey M. Davidson

2007-01-01

13

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

Microsoft Academic Search

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

Michael J. Heller; Raj Krishnan; Avery Sonnenberg

2010-01-01

14

Biological effects of nanoparticulate materials  

Microsoft Academic Search

A range of morphologically nanoparticulate materials including Ag, NiO, TiO2, multiwall carbon nanotubes, and chrysotile asbestos have been characterized by transmission electron microscopy. All but the TiO2 (anatase and rutile) were observed to exhibit some cytotoxicity at concentrations of 5 ?g\\/ml for a murine macrophage cell line as a respiratory response model. Silver exhibits interesting systemic differences for animal and

K. F. Soto; A. Carrasco; T. G. Powell; L. E. Murr; K. M. Garza

2006-01-01

15

Methanol electrooxidation on well-characterized Pt-Ru alloys.  

National Technical Information Service (NTIS)

Rate-limiting step in electrooxidation of methanol in sulfuric acid electrolyte on sputter-cleaned Pt-Ru electrodes at 25C was initial adsorption/dehydrogenation of methanol on Pt surface atom ensembles, resulting in an optimum Ru surface composition of 1...

H. A. Gasteiger P. N. Ross E. J. Cairns

1993-01-01

16

Collection and characterization of airborne nanoparticulates  

SciTech Connect

This paper describes the use of a thermal precipitation device to collect representative, airborne nanoparticulates on transmission electron microscope (TEM) grid supports and their characterization using a bright field (BF)-dark field (DF)-selected area electron diffraction (SAED)-energy dispersive spectrometry (EDS) analysis protocol. Two airborne nanoparticulate regimes are illustrated and compared: (1) general nanoparticulates, composed of nanocrystalline aggregates containing from 2 to >1000 individual particles, ranging in size from approximately 1 to 100 nm and (2) complex, branched clusters of amorphous, carbonaceous spherules (containing from 50 to >1000 spherules, which range in size from 10 to 40 nm in diameter) and carbon nanocrystal aggregates containing nanotubes and other polyhedra. Commercial nanoparticulate aggregates of TiO{sub 2} and Si{sub 3}N{sub 4} are also observed in the context of characterization standards and the nanotechnology potential for contributing to atmospheric pollutants.

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

2004-03-15

17

Nanoparticulate systems for polynucleotide delivery  

PubMed Central

Nanotechnology has tremendously influenced gene therapy research in recent years. Nanometer-size systems have been extensively investigated for delivering genes at both local and systemic levels. These systems offer several advantages in terms of tissue penetrability, cellular uptake, systemic circulation, and cell targeting as compared to larger systems. They can protect the polynucleotide from a variety of degradative and destabilizing factors and enhance delivery efficiency to the cells. A variety of polymeric and non-polymeric nanoparticles have been investigated in an effort to maximize the delivery efficiency while minimizing the toxic effects. This article provides a review on the most commonly used nanoparticulate systems for gene delivery. We have discussed frequently used polymers, such as, polyethyleneimine, poly (lactide-co-glycolide), chitosan, as well as non-polymeric materials such as cationic lipids and metallic nanoparticles. The advantages and limitations of each system have been elaborated.

Basarkar, Ashwin; Singh, Jagdish

2007-01-01

18

Oxygen adsorption on Pt/Ru(0001) layers.  

PubMed

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 O(2) 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 O(2), thereby approaching the behavior for oxygen adsorption on genuine Pt(111). For Pt monolayer films a novel state of chemisorbed O(2), 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. PMID:21682533

Jakob, Peter; Schlapka, Andreas; Gazdzicki, Pawel

2011-06-14

19

Combustion-derived nanoparticulate induces the adverse vascular effects of diesel exhaust inhalation  

PubMed Central

Aim Exposure to road traffic and air pollution may be a trigger of acute myocardial infarction, but the individual pollutants responsible for this effect have not been established. We assess the role of combustion-derived-nanoparticles in mediating the adverse cardiovascular effects of air pollution. Methods and results To determine the in vivo effects of inhalation of diesel exhaust components, 16 healthy volunteers were exposed to (i) dilute diesel exhaust, (ii) pure carbon nanoparticulate, (iii) filtered diesel exhaust, or (iv) filtered air, in a randomized double blind cross-over study. Following each exposure, forearm blood flow was measured during intra-brachial bradykinin, acetylcholine, sodium nitroprusside, and verapamil infusions. Compared with filtered air, inhalation of diesel exhaust increased systolic blood pressure (145 4 vs. 133 3 mmHg, P< 0.05) and attenuated vasodilatation to bradykinin (P= 0.005), acetylcholine (P= 0.008), and sodium nitroprusside (P< 0.001). Exposure to pure carbon nanoparticulate or filtered exhaust had no effect on endothelium-dependent or -independent vasodilatation. To determine the direct vascular effects of nanoparticulate, isolated rat aortic rings (n= 69 per group) were assessed in vitro by wire myography and exposed to diesel exhaust particulate, pure carbon nanoparticulate and vehicle. Compared with vehicle, diesel exhaust particulate (but not pure carbon nanoparticulate) attenuated both acetylcholine (P< 0.001) and sodium-nitroprusside (P= 0.019)-induced vasorelaxation. These effects were partially attributable to both soluble and insoluble components of the particulate. Conclusion Combustion-derived nanoparticulate appears to predominately mediate the adverse vascular effects of diesel exhaust inhalation. This provides a rationale for testing environmental health interventions targeted at reducing traffic-derived particulate emissions.

Mills, Nicholas L.; Miller, Mark R.; Lucking, Andrew J.; Beveridge, Jon; Flint, Laura; Boere, A. John F.; Fokkens, Paul H.; Boon, Nicholas A.; Sandstrom, Thomas; Blomberg, Anders; Duffin, Rodger; Donaldson, Ken; Hadoke, Patrick W.F.; Cassee, Flemming R.; Newby, David E.

2011-01-01

20

Hydrogen adsorption and coadsorption with CO on well-defined bimetallic PtRu surfacesa model study on the CO tolerance of bimetallic PtRu anode catalysts in low temperature polymer electrolyte fuel cells  

Microsoft Academic Search

The influence of PtRu surface alloy formation and of coadsorbed CO on the adsorption\\/desorption characteristics of hydrogen on bimetallic PtRu surfaces was investigated by temperature programmed desorption, using a 40% Pt containing PtRu surface alloy pseudomorphic on a Ru(0001) surface with an almost statistical distribution of Pt surface atoms as substrate. Alloy formation leads to a significant broadening of the

T. Diemant; T. Hager; H. E Hoster; H. Rauscher; R. J Behm

2003-01-01

21

Photosensitive liquid crystals with nanoparticulate internal structure  

NASA Astrophysics Data System (ADS)

Stabilization of thermodynamic relaxation of photoinduced cis isomers of azobenzene liquid-crystal molecules is observed in nanoparticulate networks. The phenomenon permits bistability of the phase state (anisotropic and isotropic) of the material and reversible all-optical switching between those states, resulting in strong changes in the light-scattering properties of the material. Recording of complex optical structures with high spatial resolution with the aid of laser beams of different wavelengths is demonstrated.

Tabiryan, N.; Grozhik, V.; Serak, S.

2002-11-01

22

Intratumoral Drug Delivery with Nanoparticulate Carriers  

PubMed Central

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.

Holback, Hillary

2011-01-01

23

Electrocatalytic properties of nanoporous PtRu alloy towards the electrooxidation of formic acid  

Microsoft Academic Search

The electrooxidation of formic acid has been investigated as a probe of the electrocatalytic properties of PtRu alloy having high surface area and regular nanoporous structure using cyclic voltammetry and chronoamperometry. Compared to nanostructured Pt electrocatalyst, adding Ru to Pt significantly enhances the electrocatalytic activity towards the formic acid oxidation and substantially changes the reaction kinetics. The electrocatalytic decomposition pathway

Junhua Jiang; Anthony Kucernak

2009-01-01

24

Uniform dispersion of 1?:?1 PtRu nanoparticles in ordered mesoporous carbon for improved methanol oxidation.  

PubMed

PtRu nanoparticles dispersed in CMK3 mesoporous carbons have been prepared via a CPDM (carbonization over poly-furfuryl alcohol-protected dispersed mixed metals) method. The as-synthesized CMK3 supported PtRu nanoparticles are characterized using tomography and cross-sectional TEM analysis and are compared against those synthesized by the conventional ethylene glycol (EG) method. The atomic ratio of Pt?:?Ru, which has an essential role on methanol oxidation, is found to be consistent at the nanometer scale. The good dispersion and uniform composition of PtRu nanoparticles result in improved methanol oxidation performance including higher methanol oxidation current and long-term stability. PMID:23827963

Li, Fujun; Chan, Kwong-Yu; Yung, Hoi; Yang, Chunzhen; Ting, Siu Wa

2013-08-28

25

The effect of composition of Ni-supported Pt-Ru binary anode catalysts on ethanol oxidation for fuel cells  

Microsoft Academic Search

The effect of the composition of a platinum-ruthenium (Pt-Ru) binary catalyst on a Ni-support for the anodic oxidation of ethanol in aqueous alkaline media has been studied. Co-deposition of nano-crystallites of a Pt-Ru electrocatalyst of varying composition, has been made on Ni-supports by galvanostatic deposition from precursor salt solutions of suitable composition, without using any capping agent. Conjugated scanning electron

Joyeeta Bagchi; Swapan Kumar Bhattacharya

2007-01-01

26

Preparation and characterization of multi-walled carbon nanotube (MWCNTs)-supported Pt-Ru catalyst for methanol electrooxidation  

Microsoft Academic Search

Multi-walled carbon nanotubes (MWCNTs) as a support of PtRu catalyst nanocomposites were prepared by colloid method in this work. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) all indicate that ultrasonic treatment can effectively functionalize MWCNTs, endowing them with groups that can act as nucleation sites which can favor well-dispersed deposition of PtRu clusters on their surface. The PtRu\\/MWCNTs

Chunwei Yang; Dianlong Wang; Xinguo Hu; Changsong Dai; Liang Zhang

2008-01-01

27

Nanoparticulate-catalyzed oxygen transfer processes  

DOEpatents

Nanoparticulates of oxygen transfer materials that are oxides of rare earth metals, combinations of rare earth metals, and combinations of transition metals and rare earth metals are used as catalysts in a variety of processes. Unexpectedly large thermal efficiencies are achieved relative to micron sized particulates. Processes that use these catalysts are exemplified in a multistage reactor. The exemplified reactor cracks C6 to C20 hydrocarbons, desulfurizes the hydrocarbon stream and reforms the hydrocarbons in the stream to produce hydrogen. In a first reactor stage the steam and hydrocarbon are passed through particulate mixed rare earth metal oxide to crack larger hydrocarbon molecules. In a second stage, the steam and hydrocarbon are passed through particulate material that desulfurizes the hydrocarbon. In a third stage, the hydrocarbon and steam are passed through a heated, mixed transition metal/rare earth metal oxide to reform the lower hydrocarbons and thereby produce hydrogen. Stages can be alone or combined. Parallel reactors can provide continuous reactant flow. Each of the processes can be carried out individually.

Hunt, Andrew T. (Atlanta, GA); Breitkopf, Richard C. (Dunwoody, GA)

2009-12-01

28

Nanoparticulate Alnico Thin Films with High Coercivity  

NASA Astrophysics Data System (ADS)

Alnico V (Fe--8% Al--14% Ni--24% Co--3% Cu) nanoparticulate thin films have been produced by dc magnetron sputtering. The films were sputtered on Si substrates for magnetic measurements and carbon-coated copper grids for TEM measurements. The as-deposited films have a fine grained microstructure with the bcc crystal structure. The as-made films were subjected to a full heat treatment which consists of heating the sample to 900 ^oC, then cooling it to 600 ^oC and finally annealing it at 600 ^oC for several hours. After the heat treatment, the thin films broke up into large nanoparticles (20-60 nm) surrounded by small nanoparticles (2 nm). Electron diffraction data showed that the annealed samples had an fcc structure. The maximum room temperature coercivity was found to be 2 kOe after 6h of annealing at 600 ^oC. The high coercivity could be due to strain that was induced during precipitation. The evolution of crystal structure and microstructure with annealing will be monitored and related to the observed magnetic properties.

Akdogan, Ozan; Hadjipanayis, George C.

2009-03-01

29

Formation of carbon supported PtRu alloys: an XRD analysis  

Microsoft Academic Search

Carbon supported PtRu alloys were prepared by impregnation of Pt and Ru precursors on a porous carbon support, followed by reduction of the metals with Na2S2O4. After reduction, the samples were thermal treated in argon up to 700C. The samples were characterized by atomic absorption (AAS) and X-ray diffraction (XRD) measurements. Before thermal treatment only carbon reflexions were visible in

E. Antolini; F. Cardellini

2001-01-01

30

Synthesis of Pt\\/Ru bimetallic nanoparticles in high-temperature and high-pressure fluids  

Microsoft Academic Search

A high-temperature and high-pressure flow-reactor system was applied to the synthesis of monometallic ruthenium (Ru) nanoparticles and platinum\\/ruthenium (Pt\\/Ru) bimetallic nanoparticles using the thermal reduction of ruthenium ion (Ru(III)) and the mixture of platinum (Pt(IV)) and ruthenium ions in water and ethanol mixture in the presence of poly(N-vinyl-2-pyrrolidone). Monometallic Ru nanoparticles with an average diameter of ca. 2 nm were

Masaki Ueji; Masafumi Harada; Yoshifumi Kimura

2008-01-01

31

Nano-particulate coating on cotton fabric through DBD  

NASA Astrophysics Data System (ADS)

Plasma polymerization of fluorocarbon was processed through dielectric barrier discharge (DBD). A thin hydrophobic film packed with nano-particulate structure was obtained on cotton fabric surface. The contact angle of the water and 1-bromonaphthalene on coated cotton fabric was 133 and 124 separately. The surface morphology of the coating was observed through SEM (Scanning Electronic Microscope). It was found that cotton fabric surface was tightly adhered to a thin film packed by nano-particles from 10nm to 200nm. This process showed potential applications in continuous coating of textiles with functional nano-particulate polymers, but without changing their softness performance.

Guo, Ying; Zhang, Jing; Xu, Jinzhou; Zhou, Rongming; Yu, Jianyong

2008-03-01

32

Glycerol Hydrogenolysis on Carbon-Supported PtRu and AuRu Bimetallic Catalysts  

SciTech Connect

Bimetallic PtRu and AuRu catalysts were prepared by a surface redox method in which Pt or Au was deposited onto the surface of carbon-supported Ru nanoparticles with an average diameter of 2-3 nm. Characterization by H2 chemisorption, analytical TEM, and X-ray absorption spectroscopy at the Ru K-edge, Pt LIII-edge, and Au LIII-edge confirmed that Pt and Au were successfully deposited onto Ru without disrupting the Ru particles. Depression of the ethane hydrogenolysis rate over Ru after addition of Au provided further evidence of successful deposition. The bimetallic particles were subsequently evaluated in the aqueous-phase hydrogenolysis of glycerol at 473 K and 40 bar H2 at neutral and elevated pH. Although monometallic Pt and Ru exhibited different activities and selectivities to products, the bimetallic PtRu catalyst functioned more like Ru. A similar result was obtained for the AuRu bimetallic catalyst. The PtRu catalyst appeared to be stable under the aqueous-phase reaction conditions, whereas the AuRu catalyst was altered by the harsh conditions. Gold appeared to migrate off the Ru and agglomerate on the carbon during the reaction in liquid water.

Maris,E.; Ketchie, W.; Murayama, M.; Davis, R.

2007-01-01

33

Performance of a co-electrodeposited Pt-Ru electrode for the electro-oxidation of ethanol studied by in situ FTIR spectroscopy  

Microsoft Academic Search

The ethanol electro-oxidation on a co-electrodeposited Pt-Ru catalyst was studied by in situ FTIR spectroscopy. In contrast with the formation of the known acetaldehyde, acetic acid and carbon dioxide reaction products on a Pt catalyst, on the prepared Pt-Ru electrode only carbon dioxide was detected under the same experimental conditions.

Jos P. I. Souza; Francisco J. Botelho Rabelo; Ins R. de Moraes; Francisco C. Nart

1997-01-01

34

Redesign of downstream processing techniques for nanoparticulate bioproducts  

Microsoft Academic Search

There has been much interest generated in the recov- ery of nanoparticulate (nanoparticle) bioproducts (Second generation of biotechnological products) such as plasmid DNA and viruses as putative gene therapy vectors, macromolecular assemblies as drug delivery vehicles and virus-like particles as vaccine compo- nents. Such product must be manufactured in advanced stages of purity, material definition and sophisticated formulation to rival

Mohsen Jahanshahi

2004-01-01

35

Multistrain influenza protection induced by a nanoparticulate mucosal immunotherapeutic  

Microsoft Academic Search

All commercial influenza vaccines elicit antibody responses that protect against seasonal infection, but this approach is limited by the need for annual vaccine reformulation that precludes efficient responses against epidemic and pandemic disease. In this study we describe a novel vaccination approach in which a nanoparticulate, liposome-based agent containing short, highly conserved influenza-derived peptides is delivered to the respiratory tract

W Tai; L Roberts; A Seryshev; J M Gubatan; C S Bland; R Zabriskie; S Kulkarni; L Soong; I Mbawuike; B Gilbert; F Kheradmand; D B Corry

2011-01-01

36

Natural and anthropogenic environmental nanoparticulates: Their microstructural characterization and respiratory health implications  

NASA Astrophysics Data System (ADS)

A wide range of environmental particulate matter (PM) both indoor and outdoor and consisting of natural and anthropogenic PM was collected by high volume air filters, electrostatic precipitation, and thermophoretic precipitation directly onto transmission electron microscope (TEM) coated grid platforms. These collected PM have been systematically characterized by TEM, energy-dispersive X-ray spectrometry (EDS) and scanning electron microscopy (SEM). In the El Paso, TX, USA/Juarez, Mexico metroplex 93% of outdoor PM 1 is crystalline while 40% of PM 1 is carbonaceous soot (including multiwall carbon nanotubes (MWCNTs) and multiconcentric fullerenes) PM. Multiply-replicated cytotoxicity ( in vitro) assays utilizing a human epithelial (lung model) cell line (A549) consistently demonstrated varying degrees of cell death for essentially all PM which was characterized as aggregates of nanoparticulates or primary nanoparticles. Cytokine release was detected for Fe 2O 3, chrysotile asbestos, BC, and MWCNT PM while reactive oxygen species (ROS) production has been detected for Fe 2O 3, asbestos, BC, and MWCNT aggregate PM as well as natural gas combustion PM. Nanoparticulate materials in the indoor and outdoor environments appear to be variously cytotoxic, especially carbonaceous nano-PM such as multiwall carbon nanotubes, black carbon, and soot nano-PM produced by natural gas combustion.

Murr, L. E.; Garza, K. M.

37

Potential-dependent infrared absorption spectroscopy of adsorbed CO and X-ray photoelectron spectroscopy of arc-melted single-phase Pt, PtRu, PtOs, PtRuOs, and Ru electrodes  

SciTech Connect

The potential- and coverage-dependent infrared absorption spectroscopy (IRAS) of linearly bound CO on single-phase polycrystalline arc-melted Pt, PtRu(1/1), PtRu(8/2), PtRuOs(8/1/1), PtRuOs(65/25/10), and Ru electrodes in 0.5 M H{sub 2}SO{sub 4} are correlated with the potential-dependent X-ray photoelectron spectroscopy (XPS) of the PtRu(1/1), PtOs(8.2), and PtRuOs(65/25/10) substrates. The CO stretching frequencies decrease as the mole fraction of Pt in the alloy is decreased. The CO oxidation onset on pure Pt at 100.0% CO coverage is 0.5 V vs a reversible hydrogen electrode and shifts negatively as the alloy mole fraction of Pt is reduced. At CO dosing conditions that yield 100% coverage on pure Pt, the CO bandwidths increase with decreasing Pt mole fraction: on pure Pt the bandwidths increase as the CO coverage is reduced. The effects of CO coverage and bulk alloy composition on the Stark tuning rates (STRs) have been systematically examined on Pt, and a series of binary and ternary alloy surfaces. The XPS data confirm a potential-dependent surface distribution of oxides and no significant surface segregation of the alloying components. The systematic displacement, to lower frequencies, of the linear STRs as the mole fraction of Pt is reduced suggests no significant island formation on the arc-melted alloy surfaces. The XPS data also suggest that the alloying metals, rather than Pt, are responsible for activation of the water required for methanol oxidation in the direct methanol fuel cell potential window.

Liu, R.; Iddir, H.; Fan, Q. [and others

2000-04-20

38

Encapsulation of antioxidants in gastrointestinal-resistant nanoparticulate carriers.  

PubMed

Reactive oxygen species (ROS) are known to cause several human pathologies. For this reason, antioxidants have gained utmost importance because of their potential as prophylactic and therapeutic agents in many diseases. Examples of their application include their use in diabetic patients, as aging drugs, in cancer diseases, Parkinson's, Alzheimer's, autoimmune disorders, and also in inflammation. Antioxidants have limited absorption profiles, therefore low bioavailability and low concentrations at the target site. Efforts have been done towards loading antioxidant molecules in advanced nanoparticulate carriers, e.g., liposomes, polymeric nanoparticles, solid lipid nanoparticles, self-emulsifying drug delivery system. Examples of -successful achievements include the encapsulation of drugs and other active ingredients, e.g., coenzyme Q10, vitamin E and vitamin A, resveratrol and polyphenols, curcumin, lycopene, silymarin, and superoxide dismutase. This review focuses on the comprehensive analysis of using nanoparticulate carriers for loading these molecules for oral administration. PMID:23740112

Souto, Eliana B; Severino, Patrcia; Basso, Rafael; Santana, Maria Helena A

2013-01-01

39

Dtection et caractrisation optiques d'une nanoparticule mtallique isole  

NASA Astrophysics Data System (ADS)

La dtection optique d'une nanoparticule mtallique unique par une nouvelle technique de microscopie par modulation spatiale est dcrite. Dans le cas d'un nano-objet de mtal noble, la mesure quantitative de son spectre d'absorption au voisinage de la rsonance plasmon de surface et sa comparaison prcise un modle thorique permettent une identification optique complte de l'objet tudi: taille, forme et orientation sur la surface sont dtermines.

Del Fatti, N.; Muskens, O.; Valle, F.; Huntzinger, J. R.; Billaud, P.; Broyer, M.

2006-10-01

40

Stability of carbon monoxide adsorbed on nanoparticle Pt and Pt\\/Ru electrodes in sulfuric acid media  

Microsoft Academic Search

Pt and Pt\\/Ru nanoparticle electrodes were used as substrates for studies of stability of chemisorbed CO and its interactions (exchange) with carbon monoxide and hydrogen gas admitted to sulfuric acid solution, which served as the supporting electrolyte for these measurements. The surface bound, radioactive CO was obtained after decomposition of 14C labeled methanol or formic acid from the same solution.

M. S. McGovern; P. Waszczuk; A. Wieckowski

2006-01-01

41

Mesoporous metallic cells: design of uniformly sized hollow mesoporous Pt-Ru particles with tunable shell thicknesses.  

PubMed

A new class of hollow mesoporous Pt-Ru and Pt particles with uniform size, named 'mesoporous metallic cells', are synthesized through a dual-templating approach using colloidal silica particles and non-ionic surfactants. To realize the full potential of mesoporous metals as electrocatalysts, the shell thicknesses, compositions, and hollow cavity sizes are precisely controlled. PMID:23281242

Ataee-Esfahani, Hamed; Liu, Jian; Hu, Ming; Miyamoto, Nobuyoshi; Tominaka, Satoshi; Wu, Kevin C W; Yamauchi, Yusuke

2012-12-27

42

Fabrication of Pt/Ru nanoparticle pair arrays with controlled separation and their electrocatalytic properties.  

PubMed

Aiming at the investigation of spillover and transport effects in electrocatalytic reactions on bimetallic catalyst electrodes, we have prepared novel, nanostructured electrodes consisting of arrays of homogeneously distributed pairs of Pt and Ru nanodisks of uniform size and with controlled separation on planar glassy carbon substrates. The nanodisk arrays (disk diameter ? 60 nm) were fabricated by hole-mask colloidal lithography; the separation between pairs of Pt and Ru disks was varied from -25 nm (overlapping) via +25 nm to +50 nm. Morphology and (surface) composition of the Pt/Ru nanodisk arrays were characterized by scanning electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy, the electrochemical/electrocatalytic properties were explored by cyclic voltammetry, CO(ad) monolayer oxidation ("CO(ad) stripping"), and potentiodynamic hydrogen oxidation. Detailed analysis of the CO(ad) oxidation peaks revealed that on all bimetallic pairs these cannot be reproduced by superposition of the peaks obtained on electrodes with Pt/Pt or Ru/Ru pairs, pointing to effective Pt-Ru interactions even between rather distant pairs (50 nm). Possible reasons for this observation and its relevance for the understanding of previous reports of highly active catalysts with separate Pt and Ru nanoparticles are discussed. The results clearly demonstrate that this preparation method is perfectly suited for fabrication of planar model electrodes with well-defined arrays of bimetallic nanodisk pairs, which opens up new possibilities for model studies of electrochemical/electrocatalytic reactions. PMID:21443165

Wickman, Bjrn; Seidel, Yvonne E; Jusys, Zenonas; Kasemo, Bengt; Behm, R Jrgen

2011-03-31

43

Kinetic Analysis of Nanoparticulate Polyelectrolyte Complex Interactions with Endothelial Cells  

PubMed Central

A non-toxic, nanoparticulate polyelectrolyte complex (PEC) drug delivery system was formulated to maintain suitable physicochemical properties at physiological pH. Toxicity, binding, and internalization were evaluated in relevant microvascular endothelial cells. PEC were non-toxic, as indicated by cell proliferation studies and propidium iodide staining. Inhibitor studies revealed that PEC were bound, in part, via heparan sulfate proteoglycans and internalized through macropinocytosis. A novel, flow cytometric, Scatchard protocol was established and showed that PEC, in the absence of surface modification, bind cells non-specifically with positive cooperativity, as seen by graphical transformations.

Hartig, Sean M.; Greene, Rachel; Carlesso, Gianluca; Higginbotham, James N.; Khan, Wasif N.; Prokop, Ales; Davidson, Jeffrey M.

2007-01-01

44

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

PubMed Central

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-shelltype 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.

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

2013-01-01

45

Photothermal analysis of individual nanoparticulate samples using micromechanical resonators.  

PubMed

The ability to detect and analyze single sample entities such as single nanoparticles, viruses, spores, or molecules is of fundamental interest. This can provide insight into the individual specific properties which may differ from the statistical sample average. Here we introduce resonant photothermal spectroscopy, a novel method that enables the analysis of individual nanoparticulate samples. Absorption of light by an individual sample placed on a microstring resonator results in local heating of the string, which is reflected in its resonance frequency. The working principle of the spectrometer is demonstrated by analyzing the optical absorption of different micro- and nanoparticles on a microstring. We present the measurement of a simple absorption spectrum of multiple polystyrene microparticles illuminated with an unfocused LED light source. Using a diode laser, single 170 nm polystyrene nanoparticles are detected. With the current setup, nanoparticulate samples with a mass of ~40 ag are detectable. By using nanostrings, visible and infrared photothermal spectroscopy in the subattogram mass regime is possible and single molecule detection is within reach. PMID:23799869

Larsen, Tom; Schmid, Silvan; Villanueva, Luis G; Boisen, Anja

2013-07-08

46

Synthesis and characterization of carbon black supported PtRu alloy as a model catalyst for fuel cells  

Microsoft Academic Search

A set of bimetallic PtRu catalysts prepared by co-impregnation of carbon black with ruthenium(III) chloride hydrate and hydrogen hexachloroplatinate(IV) hydrate were investigated by temperature-programmed reduction (TPR), chemisorption of hydrogen, transmission electron microscopy (TEM), microcalorimetry of adsorbed CO and a structure-sensitive reaction (n-hexane conversion). The results showed that the volumetric capacities for CO and H2 adsorption is influenced in the bimetallic

Yao Jun Zhang; A. Maroto-Valiente; I. Rodriguez-Ramos; Qin Xin; A. Guerrero-Ruiz

2004-01-01

47

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

Microsoft Academic Search

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

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

2009-01-01

48

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

Microsoft Academic Search

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

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

2008-01-01

49

Electro- and nonlinear optics of liquid crystal materials with nanoparticulate internal structure  

NASA Astrophysics Data System (ADS)

The combination of liquid crystals (LCs) and reconfigurable nanoparticulate networks results in most versatile materials for controlling light beams. These material systems can be used for developing multi-functional reconfigurable photonics and opto-electronics components and spatial light modulators with ultimate light modulating capabilities. We review here our results in laser recording of one and two-dimensional diffraction gratings and gratings with variable pitch. Nonlinear optical properties of LC with nanoparticulate internal networks and diffraction gratings laser-recorded in these materials are discussed. Nanoparticulate networks are capable of stabilizing the thermodynamic relaxation of photoinduced cis-isomers of molecules in photosensitive azobenzene LCs used as host for the nanoparticulate network leading to bistability of the phase state (anisotropic and isotropic) of the material, and reversible all-optical switching between those states.

Tabiryan, Nelson; Grozhik, Vladimir; Nersisyan, Sarik; Serak, Svetlana

2003-11-01

50

The synthesis of metal nanoparticulate catalysts within functional microgel particles  

NASA Astrophysics Data System (ADS)

Electrostatically and sterically stabilized polymer microgel particles have been prepared containing either amino (poly(2-(diethylamino)ethyl methacrylate), PDEA) or carboxylic acid (poly(acrylic acid), PAA; poly(methacrylic acid), PMMA) functional groups. The PDEA, PAA and PMAA particles can be used for the incorporation of a large variety of metal nanoparticulate catalysts due to their functional amine and carboxylic acid groups; Pd, Ru and Ni nanoparticles have been synthesized. The more polar PAA microgels were designed as the nanocatalyst carrier system in aqueous reaction media while the less polar PMAA particles were prepared as the metal nanoparticle template for use in catalytic reactions that take place in organic solvents. The sterically and electrostatically stabilized microgel particles possess surface functional groups that can potentially interact with the microchannel walls of microfluidic catalytic reactors.

Kaliva, Maria; Pavlopoulou, Eleni; Christodoulakis, Konstantinos; Vamvakaki, Maria; Anastasiadis, Spiros H.

2012-02-01

51

Functionally Graded Dual-Nanoparticulate-Reinforced Aluminum Matrix Composite Materials  

NASA Astrophysics Data System (ADS)

Functionally graded carbon nanotubes (CNT) and nano Silicon carbide (nSiC) reinforced aluminum (Al) matrix composite materials were fully densified by a simple ball milling and hot-pressing processes. The nSiC was used as a physical mixing agent to increase dispersity of the CNT in the Al particles. It was observed that the CNT was better dispersed in the Al particles with a nSiC mixing agent compared to without it used. SEM micrograph showed that the interface of the each layers had very tightly adhesion without any serious pores and micro-cracks. This functionally graded dual-nanoparticulate-reinforced Al matrix composite by powder metallurgical approach could also be applied to comples matrix materials.

Kwon, Hansang; Lee, Gil-Geun; Leparoux, Marc; Kawasaki, Akira

2013-03-01

52

A TEM analysis of nanoparticulates in a Polar ice core  

SciTech Connect

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.

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

2004-03-15

53

Realization assessment of stabilizer with presonication on size-distribution of itraconazole nanoparticulate in wet-nanomilling  

Microsoft Academic Search

The paper investigates fabrication of itraconazole nanoparticulate in wet-nanomilling by appropriate alteration of the suspension properties and the milling parameters. By wet-nanomilling, stable nano-scale particulate can be prepared which have better physical properties. In this study, effects of adding stabilizer on nanoparticulate size and polydispersity index were performed during production of itraconazole nanoparticulate. In addition, the effect of pre-sonication followed

R. Radzuan; A. B. Abdul Majeed; T. Julianto; M. K. Hamzah; N. R. Hamzah; N. I. Bukhari

2009-01-01

54

Lattice gas model for CO electrooxidation on Pt-Ru bimetallic surfaces  

SciTech Connect

The authors propose a lattice gas model for the carbon monoxide oxidation on platinum-ruthenium electrode surfaces. The kinetic model includes the main mechanistic bifunctional features as they are generally agreed upon in the literature. The CO stripping voltammetry is solved by dynamic Monte Carlo simulations. For a randomly dispersed alloy of Ru and Pt, the model gives a satisfactory semiquantitative agreement with the experimental CO stripping results of Gasteiger et al. [Journal of Physical Chemistry 1994, 98, 617]. It is shown how the bifunctional mechanism cannot operate if CO is not mobile on the surface, and a simple Tafel-type experiment with a low concentration of active Pt-Ru sites is suggested to check quantitatively the Co mobility rate. On a surface with large Ru islands, the overpotential for CO oxidation increases, and two CO stripping peaks may appear if the CO mobility is sufficiently low. A mean-field model of the system reproduces the DMC results for high CO mobility but breaks down for a system with large Ru islands and a comparatively low CO surface diffusion constant.

Koper, M.T.M.; Jansen, A.P.J.; Santen, R.A. van [Schuit Inst. of Catalysis, Eindhoven (Netherlands). Lab. of Inorganic Chemistry and Catalysis; Lukkien, J.J. [Eindhoven Univ. of Technology (Netherlands). Dept. of Mathematics and Computing Science

1999-07-01

55

Structural and Architectural Evaluation of Bimetallic Nanoparticles: A Case Study of PtRu CoreShell and Alloy  

Microsoft Academic Search

A comprehensive structural\\/architectural evaluation of the PtRu (1:1) alloy and Ru@Pt coreshell nanoparticles(NPs)providesspatiallyresolvedstructuralinformationonsub-5nmNPs.Acombinationofextended X-ray absorptionfine structure (EXAFS), X-ray absorption near edge structure (XANES), pair distribution function (PDF) analyses, Debye function simulations of X-ray diffraction (XRD), andfield emission transmission electron microscopy\\/energy dispersive spectroscopy (FE-TEM\\/EDS) analyses provides complementary information used to construct a detailed picture of the core\\/shell and alloy nanostructures. The

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

56

Monolithic precolumns as efficient tools for guiding the design of nanoparticulate drug-delivery formulations.  

PubMed

The development of nanomedicines for improved diagnosis and treatment of diseases is pushing current analytical methods to their limits. More efficient, quantitative high-throughput screening methods are needed to guide the optimization of promising nanoparticulate drug delivery formulations. In response to this need, we present herein a novel approach using monolithic separation media. The unique porosity of our capillary monolithic precolumns allows the direct injection and online removal of protamine-oligonucleotide nanoparticles ("proticles") without column clogging, thus avoiding the need for time-consuming off-line sample workup. Furthermore, ring-opening metathesis polymerization (ROMP)-derived monoliths show equivalent preconcentration efficiency for the target drug vasoactive intestinal peptide (VIP) as conventional particle-packed precolumns. The performance of the ROMP-derived monolithic precolumns was constant over at least 100 injections of crude proticle-containing and 300 injections of highly acidic samples. Applying a validated LC-MS/MS capillary monolithic column switching method, we demonstrate the rapid determination of both drug load and in vitro drug release kinetics of proticles within the critical first 2 h and investigate the stability of VIP-loaded proticles in aqueous storage medium intended for inhalation therapy. PMID:22861123

Gatschelhofer, Christina; Prasch, Agnes; Buchmeiser, Michael R; Zimmer, Andreas; Wernig, Karin; Griesbacher, Martin; Pieber, Thomas R; Sinner, Frank M

2012-08-22

57

Nucleic Acids Bind to Nanoparticulate iron (II) Monosulphide in Aqueous Solutions  

NASA Astrophysics Data System (ADS)

In the hydrothermal FeS-world origin of life scenarios nucleic acids are suggested to bind to iron (II) monosulphide precipitated from the reaction between hydrothermal sulphidic vent solutions and iron-bearing oceanic water. In lower temperature systems, the first precipitate from this process is nanoparticulate, metastable FeSm with a mackinawite structure. Although the interactions between bulk crystalline iron sulphide minerals and nucleic acids have been reported, their reaction with nanoparticulate FeSm has not previously been investigated. We investigated the binding of different nucleic acids, and their constituents, to freshly precipitated, nanoparticulate FeSm. The degree to which the organic molecules interacted with FeSm is chromosomal DNA > RNA > oligomeric DNA > deoxadenosine monophosphate ? deoxyadenosine ? adenine. Although we found that FeSm does not fluoresce within the visible spectrum and there is no quantum confinement effect seen in the absorption, the mechanism of linkage of the FeSm to these biomolecules appears to be primarily electrostatic and similar to that found for the attachment of ZnS quantum dots. The results of a preliminary study of similar reactions with nanoparticulate CuS further supported the suggestion that the interaction mechanism was generic for nanoparticulate transition metal sulphides. In terms of the FeS-world hypothesis, the results of this study further support the idea that sulphide minerals precipitated at hydrothermal vents interact with biomolecules and could have assisted in the formation and polymerisation of nucleic acids.

Hatton, Bryan; Rickard, David

2008-06-01

58

Microstructures and nanostructures for environmental carbon nanotubes and nanoparticulate soots.  

PubMed

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 ( approximately 5 to 50 nm diameter) differentiate themselves from multiconcentric fullerenic nanoparticles and especially turbostratic BC and carbonaceous soot nanospherules ( approximately 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

Murr, L E

2008-12-01

59

Nanoparticulate carriers for the treatment of coronary restenosis  

PubMed Central

The current treatment for coronary restenosis following balloon angioplasty involves the use of a mechanical or a drug-eluting stent. Despite the high usage of commercially-available drug-eluting stents in the cardiac field, there are a number of limitations. This review will present the background of restenosis, go briefly into the molecular and cellular mechanisms of restenosis, the use of mechanical stents in coronary restenosis, and will provide an overview of the drugs and genes tested to treat restenosis. The primary focus of this article is to present a comprehensive overview on the use of nanoparticulate delivery systems in the treatment of restenosis both in-vitro and in-vivo. Nanocarriers have been tested in a variety of animal models and in human clinical trials with favorable results. Polymer-based nanoparticles, liposomes, and micelles will be discussed, in addition to the findings presented in the field of cardiovascular drug targeting. Nanocarrier-based delivery presents a viable alternative to the current stent based therapies.

Brito, Luis; Amiji, Mansoor

2007-01-01

60

Structural and architectural evaluation of bimetallic nanoparticles: a case study of Pt-Ru core-shell and alloy nanoparticles.  

PubMed

A comprehensive structural/architectural evaluation of the PtRu (1:1) alloy and Ru@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 (FE-TEM/EDS) analyses provides complementary information used to construct a detailed picture of the core/shell and alloy nanostructures. The 4.4 nm PtRu (1:1) alloys are crystalline homogeneous random alloys with little twinning in a typical face-centered cubic (fcc) cell. The Pt atoms are predominantly metallic, whereas the Ru atoms are partially oxidized and are presumably located on the NP surface. The 4.0 nm Ru@Pt NPs have highly distorted hcp Ru cores that are primarily in the metallic state but show little order beyond 8 A. In contrast, the 1-2 monolayer thick Pt shells are relatively crystalline but are slightly distorted (compressed) relative to bulk fcc Pt. The homo- and heterometallic coordination numbers and bond lengths are equal to those predicted by the model cluster structure, showing that the Ru and Pt metals remain phase-separated in the core and shell components and that the interface between the core and shell is quite normal. PMID:19731934

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

2009-10-27

61

Influence of KOH-activated graphite nanofibers on the electrochemical behavior of Pt-Ru nanoparticle catalysts for fuel cells  

NASA Astrophysics Data System (ADS)

Graphite nanofibers (GNFs) were activated chemically by a heat treatment at between 700 and 1000 C. The GNFs were used as carbon supports for Pt-Ru nanoparticles in fuel cells. The surface, structural, and textural characteristics of the carbon supports and Pt-Ru/KOH-activated GNFs catalysts were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and surface area analyzer, respectively. The electrochemical activity was examined by cyclic voltammetry. The results showed that the concentration of oxygen functional groups and the specific surface area of the carbon supports increased with increasing activation temperature up to 900 C, whereas the mean Pt-Ru nanoparticle size decreased due to an improvement in the dispersibility of the Pt-Ru/KOH-activated GNFs catalysts. From the results, it was found that the electrochemical activities of the Pt-Ru/KOH-activated GNFs catalysts were improved by the larger active surface area available due to an increase in the number of oxygen functional groups and specific surface area, resulting in the enhanced electrochemical activity for use in fuel cells.

Lee, Seul-Yi; Kim, Byung-Ju; Park, Soo-Jin

2013-03-01

62

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

PubMed Central

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.

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

2013-01-01

63

Pharmaceutical development and regulatory considerations for nanoparticles and nanoparticulate drug delivery systems.  

PubMed

Pharmaceutical nanomaterials (NMs) encompass a wide variety of materials including drug nanoparticles (NPs), which can be amorphous or crystalline; or nanoparticulate drug delivery systems, such as micelles, microemulsions, liposomes, drug-polymer conjugates, and antibody-drug conjugates. These NMs are either transient or persistent-depending on whether the integrity of their structure and size is maintained until reaching the site of drug action. Examples of several approved drug products are included as pharmaceutical nanoparticulate systems along with a commentary on the current development issues and paradigms for various categories ofNPs. This commentary discusses the preparation of nanoparticulate systems for commercial development, and the biopharmaceutical and pharmacokinetic advantages of these systems. A criterion of criticality is defined that incorporates the structure, in addition to size requirement of pharmaceutical NPs to identify systems that may require special development and regulatory considerations. 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:3867-3882, 2013. PMID:24037829

Narang, Ajit S; Chang, Rong-Kun; Hussain, Munir A

2013-08-23

64

Combustion-Generated Nanoparticulates in the El Paso, TX, USA / Juarez, Mexico Metroplex: Their Comparative Characterization and Potential for Adverse Health Effects  

PubMed Central

In this paper we report on the collection of fine (PM1) and ultrafine (PM0.1), or nanoparticulate, carbonaceous materials using thermophoretic precipitation onto silicon monoxide/formvar-coated 3 mm grids which were examined in the transmission electron microscope (TEM). We characterize and compare diesel particulate matter (DPM), tire particulate matter (TPM), wood burning particulate matter, and other soot (or black carbons (BC)) along with carbon nanotube and related fullerene nanoparticle aggregates in the outdoor air, as well as carbon nanotube aggregates in the indoor air; and with reference to specific gas combustion sources. These TEM investigations include detailed microstructural and microdiffraction observations and comparisons as they relate to the aggregate morphologies as well as their component (primary) nanoparticles. We have also conducted both clinical surveys regarding asthma incidence and the use of gas cooking stoves as well as random surveys by zip code throughout the city of El Paso. In addition, we report on short term (2 day) and longer term (2 week) in vitro assays for black carbon and a commercial multiwall carbon nanotube aggregate sample using a murine macrophage cell line, which demonstrate significant cytotoxicity; comparable to a chrysotile asbestos nanoparticulate reference. The multi-wall carbon nanotube aggregate material is identical to those collected in the indoor and outdoor air, and may serve as a surrogate. Taken together with the plethora of toxic responses reported for DPM, these findings prompt concerns for airborne carbonaceous nanoparticulates in general. The implications of these preliminary findings and their potential health effects, as well as directions for related studies addressing these complex issues, will also be examined.

Murr, L. E.; Soto, K. F.; Garza, K. M.; Guerrero, P. A.; Martinez, F.; Esquivel, E. V.; Ramirez, D. A.; Shi, Y.; Bang, J. J.; Venzor, J.

2006-01-01

65

Nanoparticulate Iron Oxide Minerals in Soils and Sediments: Unique Properties and Contaminant Scavenging Mechanisms  

Microsoft Academic Search

Nanoparticulate goethite, akaganeite, hematite, ferrihydrite and schwertmannite are important constituents of soils, sediments and mine drainage outflows. These minerals have high sorption capacities for metal and anionic contaminants such as arsenic, chromium, lead, mercury and selenium. Contaminant sequestration is accomplished mainly by surface complexation, but aggregation of particles may encapsulate sorbed surface species into the multigrain interior interfaces, with significant

Glenn A. Waychunas; Christopher S. Kim; Jillian F. Banfield

2005-01-01

66

Application of Size Exclusion Chromatography in the Development and Characterization of Nanoparticulate Drug Delivery Systems  

Microsoft Academic Search

The successful production of effective nanoparticulate drug delivery systems depends on maintaining the characteristics of the starting materials and the final formulation. Since compendial standards for traditional drug delivery systems do not always apply to nanosystems, analytical procedures for nanosized delivery systems must be established. This will ensure the quality of such products as they reach the marketplace. Size exclusion

Daniel P. Otto; Hermanus C. M. Vosloo; Melgardt M. de Villiers

2007-01-01

67

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

NASA Astrophysics Data System (ADS)

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.

Tang, Xiangyang; Yang, Yi; Tang, Shaojie

2011-03-01

68

High performance direct methanol polymer electrolyte fuel cells  

Microsoft Academic Search

Direct methanol fuel cells (DMFCs) using Pt-Ru electrocatalysts and perfluorosulfonic acid membranes provide high performances if operated above 100 C with optimized catalyst layers. A decal transfer method is used to apply thin-film catalyst\\/ionomer composite layers to Nafion{reg_sign} membranes. A Nafion 112 membrane\\/electrode assembly operating on 5 atm oxygen at 130 C yields a current of 670 mA\\/cm² at 0.5

Xiaoming Ren; M. S. Wilson; S. Gottesfeld

1996-01-01

69

Low temperature NO 2 sensitivity of nano-particulate SnO 2 film for work function sensors  

Microsoft Academic Search

Work function based investigations of NO2 sensitivity of tin oxide (SnO2) nano-particulate films were carried out at low temperatures under different humidity conditions. A simple preparation technique was employed to obtain stoichiometric nano-particulate SnO2 films. The nano-particles size was determined by atomic force microscopy (AFM) and the work function measurements were done at 130C by a computer controlled Kelvin probe

A. Karthigeyan; R. P. Gupta; K. Scharnagl; M. Burgmair; M. Zimmer; S. K. Sharma; I. Eisele

2001-01-01

70

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

SciTech Connect

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.

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

71

Sequential determination of platinum, ruthenium, and molybdenum in carbon-supported Pt, PtRu, and PtMo catalysts by atomic absorption spectrometry  

Microsoft Academic Search

A simple accurate and precise analytical method for the determination of platinum, ruthenium, and molybdenum in Pt, PtRu, and PtMo nanoparticles catalysts deposited on high-surface area carbon by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) is described. The complete digestion of samples (0.0100.020g), which contain noble metals (NMs) in the range between 0 and 30%

Silvera Scaccia; Barbara Goszczynska

2004-01-01

72

Insights into the electro-oxidation of ethylene glycol at Pt\\/Ru nanocatalysts supported on MWCNTs: Adsorption-controlled electrode kinetics  

Microsoft Academic Search

Electrocatalytic properties of Pt\\/Ru nanoparticle-electrodecorated MWCNT platform towards the oxidation of ethylene glycol (EG) have been interrogated using cyclic voltammetry and electrochemical impedance spectroscopy. Both forward and reverse oxidative reactions exhibited distinct electrochemical behaviour following changes in EG concentrations, scan rates and during repetitive cyclic voltammetric scanning. Our results suggest that the overall electro-oxidation reaction of EG is governed mainly

Nobanathi W. Maxakato; Christopher J. Arendse; Kenneth I. Ozoemena

2009-01-01

73

Ethylene glycol oxidation on Pt and PtRu nanoparticle decorated polythiophene\\/multiwalled carbon nanotube composites for fuel cell applications  

Microsoft Academic Search

A novel supporting material containing polythiophene (PTh) and multiwalled carbon nanotubes (MWCNTs) (PThCNTs) is prepared by in situ polymerization of thiophene on carbon nanotubes using FeCl3 as oxidizing agent under sonication. The prepared polythiophene\\/CNT composites are further decorated with Pt and PtRu nanoparticles by chemical reduction of the corresponding metal salts using HCHO as reducing agent at pH = 11

Vaithilingam Selvaraj; Muthukaruppan Alagar

2008-01-01

74

Formation of PtRu alloy nanoparticle catalyst by radiolytic process assisted by addition of dl -tartaric acid and its enhanced methanol oxidation activity  

Microsoft Academic Search

PtRu nanoparticle catalysts with 2-nm size supported on carbon were synthesized by a radiolytic process, assisted with the\\u000a addition of dl-tartaric acid. Gradual alloying with the addition was confirmed by structural analyses with techniques of the X-ray diffraction\\u000a and the X-ray absorption fine structure. Their methanol oxidation activities evaluated by the linear sweep voltammetry were\\u000a higher than that of the

Satoru Kageyama; Satoshi Seino; Takashi Nakagawa; Hiroaki Nitani; Koji Ueno; Hideo Daimon; Takao A. Yamamoto

75

Expanded Bed Chromatography as a Tool for Nanoparticulate Separation: Kinetic Study and Adsorption of Protein Nanoparticles  

Microsoft Academic Search

Expanded bed adsorption was investigated together with its suitability for the practical recovery of nanoparticulate mimics\\u000a of products such as plasmid DNA and viruses as putative gene therapy vectors. The study assessed the binding of protein nanoparticles\\u000a fabricated from bovine serum albumin (BSA) with average size of 80nm as a model system and viral size\\/charge mimic to the\\u000a streamline DEAE

Mohsen Jahanshahi; Melika Ebrahimpour

2009-01-01

76

Seeded growth of robust SERS-active 2D Au@Ag nanoparticulate films  

SciTech Connect

We demonstrate herein a novel and versatile solution-based methodology for fabricating self-organized two-dimensional (2D) Au nanoparticle arrays on glass using in situ nucleation at an aminosilane monolayer followed by seeded, electroless growth; subsequent deposition of Ag produced Au{at}Ag core-shell nanoparticulate films which proved highly promising as surface-enhanced Raman scattering (SERS) platforms.

Baker, Gary A [ORNL; Dai, Sheng [ORNL; Hagaman, Edward {Ed} W [ORNL; Mahurin, Shannon Mark [ORNL; Zhu, Haoguo [ORNL; Bao, Lili [Oak Ridge National Laboratory (ORNL)

2008-01-01

77

Nanoparticulate-induced toxicity and related mechanism invitro and invivo  

Microsoft Academic Search

In urban areas, the quantity of exhaust particles from vehicle emissions is tremendous and has been regarded as the main contributor\\u000a to particulate matter (PM) pollution. Recently, the nano-sized PM on public health has begun to raise the attention. The increased\\u000a toxicity of nanoparticulate can be largely explained by their small size, high airborne concentration, extensive surface area\\u000a and high

Hye Won Kim; Eun-Kyung Ahn; Bo Keun Jee; Hyoung-Kyu Yoon; Kweon Haeng Lee; Young Lim

2009-01-01

78

Mssbauer analysis of the phase distribution present in nanoparticulate Fe/SiO2 samples  

NASA Astrophysics Data System (ADS)

Results are presented on the phase distribution and magnetic properties of nanoparticulate Fe/SiO2 samples prepared by high-energy ball milling. From our data, we suggest that the elevated coercivities measured in the samples are linked to the coupling of the core of the particles (?-Fe) with a highly disordered phase present in their surface region and whose behavior exhibits some similarities with a spin-glass phase.

de Julin, C.; Alczar, G. A. Prez; Cebollada, F.; Montero, M. I.; Gonzlez, J. M.; Marco, J. F.

1999-08-01

79

Effect of voids and pressure on melting of nano-particulate and bulk aluminum  

Microsoft Academic Search

Molecular dynamics simulations are performed using isobaricisoenthalpic (NPH) ensembles to study the effect of internal defects\\u000a in the form of voids on the melting of bulk and nano-particulate aluminum in the size range of 29nm. The main objectives\\u000a are to determine the critical interfacial area required to overcome the free energy barrier for the thermodynamic phase transition,\\u000a and to explore

Puneesh Puri; Vigor Yang

2009-01-01

80

Preparation and characterization of silica nanoparticulate polyacrylonitrile composite and porous nanofibers  

NASA Astrophysics Data System (ADS)

In this study, polyacrylonitrile (PAN) composite nanofibers containing different amounts of silica nanoparticulates have been obtained via electrospinning. The surface morphology, thermal properties and crystal structure of PAN/silica nanofibers are characterized using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, wide-angle x-ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results indicate that the addition of silica nanoparticulates affects the structure and properties of the nanofibers. In addition to PAN/silica composite nanofibers, porous PAN nanofibers have been prepared by selective removal of the silica component from PAN/silica composite nanofibers using hydrofluoric (HF) acid. ATR-FTIR and thermal gravimetric analysis (TGA) experiments validate the removal of silica nanoparticulates by HF acid, whereas SEM and TEM results reveal that the porous nanofibers obtained from composite fibers with higher silica contents exhibited more nonuniform surface morphology. The Brunauer-Emmett-Teller (BET) surface area of porous PAN nanofibers made from PAN/silica (5 wt%) composite precursors is higher than that of pure nonporous PAN nanofibers.

Ji, Liwen; Saquing, Carl; Khan, Saad A.; Zhang, Xiangwu

2008-02-01

81

Preparation and characterization of silica nanoparticulate-polyacrylonitrile composite and porous nanofibers.  

PubMed

In this study, polyacrylonitrile (PAN) composite nanofibers containing different amounts of silica nanoparticulates have been obtained via electrospinning. The surface morphology, thermal properties and crystal structure of PAN/silica nanofibers are characterized using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, wide-angle x-ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results indicate that the addition of silica nanoparticulates affects the structure and properties of the nanofibers. In addition to PAN/silica composite nanofibers, porous PAN nanofibers have been prepared by selective removal of the silica component from PAN/silica composite nanofibers using hydrofluoric (HF) acid. ATR-FTIR and thermal gravimetric analysis (TGA) experiments validate the removal of silica nanoparticulates by HF acid, whereas SEM and TEM results reveal that the porous nanofibers obtained from composite fibers with higher silica contents exhibited more nonuniform surface morphology. The Brunauer-Emmett-Teller (BET) surface area of porous PAN nanofibers made from PAN/silica (5wt%) composite precursors is higher than that of pure nonporous PAN nanofibers. PMID:21730729

Ji, Liwen; Saquing, Carl; Khan, Saad A; Zhang, Xiangwu

2008-02-01

82

Development and operation of a 150 W air-feed direct methanol fuel cell stack  

Microsoft Academic Search

A five-cell 150 W air-feed direct methanol fuel cell (DMFC) stack was demonstrated. The DMFC cells employed Nafion 117 as a solid polymer electrolyte membrane and high surface area carbon supported Pt-Ru and Pt catalysts for methanol electrooxidation and oxygen reduction, respectively. Stainless steel-based stack housing and bipolar plates were utilized. Electrodes with a 225 cm2 geometrical area were manufactured

D. Buttin; M. Dupont; M. Straumann; R. Gille; J. C. Dubois; R. Ornelas; G. P. Fleba; E. Ramunni; V. Antonucci; A. S. Aric; P. Cret; E. Modica; M. Pham-Thi; J. P. Ganne

2001-01-01

83

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

NASA Astrophysics Data System (ADS)

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 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 , 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.

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

2009-06-01

84

Nanoparticulate cerium dioxide and cerium dioxide-titanium dioxide composite thin films on glass by aerosol assisted chemical vapour deposition  

NASA Astrophysics Data System (ADS)

Two series of composite thin films were deposited on glass by aerosol assisted chemical vapour deposition (AACVD)nanoparticulate cerium dioxide and nanoparticulate cerium dioxide embedded in a titanium dioxide matrix. The films were analysed by a range of techniques including UV-visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive analysis by X-rays. The AACVD prepared films showed the functional properties of photocatalysis and super-hydrophilicity. The CeO 2 nanoparticle thin films displaying photocatalysis and photo-induced hydrophilicity almost comparable to that of anatase titania.

Qureshi, Uzma; Dunnill, Charles W.; Parkin, Ivan P.

2009-11-01

85

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

Microsoft Academic Search

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 worlds 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

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

2008-01-01

86

Novel Nanoparticulate Gel Formulations of Steroids for the Treatment of Macular Edema  

PubMed Central

Purpose: This article describes the development and characterization of PLGA nanoparticles of dexamethasone (DEX), hydrocortisone acetate (HA), and prednisolone acetate (PA) suspended in thermosensitive gels indicated for the treatment of macular edema (ME). Methods: Nanoparticles were prepared by oil-in-water (O/W) emulsion and dialysis methods using PLGA 50:50 and PLGA 65:35. These particles were characterized for entrapment efficiency, size distribution, surface morphology, crystallinity, and in vitro release. Further, ex vivo permeation studies of DEX in suspension and nanoparticulate formulations were carried out across the rabbit sclera. Results: Entrapment efficiencies of DEX, HA, and PA were found to be lower with the dialysis method. O/W emulsion/solvent evaporation technique resulted in higher entrapment efficiencies, that is, 77.3%, 91.3%, 92.3% for DEX, HA, and PA, respectively. Release from nanoparticles suspended in thermosensitive gels followed zero-order kinetics with no apparent burst effect. Ex vivo permeability studies further confirmed sustained release of DEX from nanoparticles suspended in thermosensitive gels. Conclusions: These novel nanoparticulate systems containing particles suspended in thermosensitive gels may provide sustained retina/choroid delivery of steroids following episcleral administration.

2010-01-01

87

Nanoparticulate Transport of Oximes over an In Vitro Blood-Brain Barrier Model  

PubMed Central

Background Due to the use of organophosphates (OP) as pesticides and the availability of OP-type nerve agents, an effective medical treatment for OP poisonings is still a challenging problem. The acute toxicity of an OP poisoning is mainly due to the inhibition of acetylcholinesterase (AChE) in the peripheral and central nervous systems (CNS). This results in an increase in the synaptic concentration of the neurotransmitter acetylcholine, overstimulation of cholinergic receptors and disorder of numerous body functions up to death. The standard treatment of OP poisoning includes a combination of a muscarinic antagonist and an AChE reactivator (oxime). However, these oximes can not cross the blood-brain barrier (BBB) sufficiently. Therefore, new strategies are needed to transport oximes over the BBB. Methodology/Principal Findings In this study, we combined different oximes (obidoxime dichloride and two different HI 6 salts, HI 6 dichloride monohydrate and HI 6 dimethanesulfonate) with human serum albumin nanoparticles and could show an oxime transport over an in vitro BBB model. In general, the nanoparticulate transported oximes achieved a better reactivation of OP-inhibited AChE than free oximes. Conclusions/Significance With these nanoparticles, for the first time, a tool exists that could enable a transport of oximes over the BBB. This is very important for survival after severe OP intoxication. Therefore, these nanoparticulate formulations are promising formulations for the treatment of the peripheral and the CNS after OP poisoning.

Wagner, Sylvia; Kufleitner, Jurgen; Zensi, Anja; Dadparvar, Miriam; Wien, Sascha; Bungert, Judith; Vogel, Tikva; Worek, Franz; Kreuter, Jorg; von Briesen, Hagen

2010-01-01

88

n-type perylene to fill voids in solution processed nanoparticulate zinc oxide thin films  

NASA Astrophysics Data System (ADS)

Using nanoparticle dispersions for printing of semiconductors would be the easiest way to evolve from classic printing technologies towards printed electronics. However, nanoparticular thin films are unfavorable in transistor applications due to two reasons: (i) The charge transport in the thin film or at its interfaces to the gate dielectric is disturbed by the voids between the nanoparticles. (ii) These layers are highly sensitive to surface adsorbates due to their high surface to volume ratio. Atmospheric surface adsorbates, e.g. on metal oxides are known to influence the electrical properties of the thin films. In order to overcome the disadvantages of the nanoparticulate thin film, this work targets both issues with a combined approach. By choosing a qualified surface adsorbate, the perturbing surface of the nanoparticles will be passivated. By using the surface adsorbate as a linker to an electron conducting organic molecule, the n-type organic will be eligible for filling the voids between the particles. We present the synthesis of a new pyrrolidone functionalized n-type perylene diimide and its application in hetero-layer nanoparticulate zinc oxide (ZnO) field-effect transistors.

Bubel, Simon; Ringk, Andreas; Strohriegl, Peter; Schmechel, Roland

2012-07-01

89

Design and assembly of solid-phases for the effective recovery of nanoparticulate bioproducts in fluidised bed contactors  

Microsoft Academic Search

Practical recovery of nanoparticulate bioproducts from suspension feedstocks has been studied in batch, fixed bed and fluidised bed adsorptive contactors. The performance of five discrete configurations of adsorbent solid phase has been critically evaluated in the anion exchange recovery of mg quantities of BSA nanoparticles. These have served as surrogate size mimics of less easily sourced viral and plasmid gene

Zhanren Zhang; Simon Burton; Sharon Williams; Eric Thwaites; Andrew Lyddiatt

2001-01-01

90

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

Microsoft Academic Search

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

Qinbai Fan; C. Pu; E. S. Smotkin

1996-01-01

91

Generation of Oxidants From the Reaction of Nanoparticulate Zero-Valent Iron and Oxygen for the use in Contaminant Remediation  

NASA Astrophysics Data System (ADS)

The reaction of zero-valent iron (ZVI) with oxygen can lead to the formation of oxidants, which may be used to transform recalcitrant contaminants including non-polar organics and certain metals. Nanoparticulate iron might provide a practical mechanism of remediating oxygen-containing groundwater and contaminated soil. To gain insight into the reaction mechanism and to quantify the yield of oxidants, experiments were performed with model organic compounds in the presence of nanoparticulate zero-valent iron and oxygen. At pH values below 5, ZVI nanoparticles were oxidized within 30 minutes with a stoichiometry of approximately two Fe0 oxidized per O2 consumed. Using the oxidation of methanol and ethanol to formaldehyde and acetaldehyde, respectively, we found that less than 2% of the consumed oxygen was converted to reactive oxidants under acidic conditions. The yield of aldehydes increased with pH up to pH 7, with maximum oxidant yields of around 5% relative to the mass of ZVI added. The increase of aldehyde yield with pH was attributable to changes in the processes responsible for oxidant production. At pH values below 5, the corrosion of ZVI by oxygen produces hydrogen peroxide, which subsequently reacts with ferrous iron [Fe(II)] via the Fenton reaction. At higher pH values, the aldehydes are produced when Fe(II), the initial product of ZVI oxidation, reacts with oxygen. The decrease in oxidant yield at pH values above 7 may be attributable to precipitation of Fe(II). The oxidation of benzoic acid and 2-propanol to para-hydroxybenzoic acid and acetone, respectively, followed a very different trend compared to the primary alcohols. In both cases, the highest product yields (approximately 2% with respect to ZVI added) were observed at pH 3. Yields decreased with increasing pH, with no oxidized product detected at neutral pH. These results suggest that two different oxidants may be produced by the system: hydroxyl radical (OH-) at acidic pH and a more selective oxidant such as the ferryl ion [Fe(IV)] at neutral pH. This provides insight into the type of compounds that may be oxidized using the zero-valent iron and oxygen system. The addition of certain compounds such as oxalate and polyoxometalate (POM) may improve contaminant remediation efficiencies by enhancing oxidant yields. The introduction of 1 mM oxalate improved the formaldehyde yield by approximately 20% at neutral pH. Oxalate accelerates the Fenton reaction and limits the passivation of the ZVI surface by increasing iron solubility. The presence of excess POM greatly enhanced the yield of formaldehyde, with maximum yields of 60 and 35% with respect to ZVI added at pH 2 and 7, respectively. The mechanism of POM enhancement is a function of solution pH. At acidic pH, POM acts an electron shuttle by directly transferring electrons from ZVI to oxygen to increase the hydrogen peroxide production. At neutral pH, POM may act by forming soluble iron-complexes and preventing the build-up of an iron oxide layer on the ZVI surface.

Keenan, C. R.; Lee, C.; Sedlak, D. L.

2007-12-01

92

Nanoparticulate mackinawite formation; a stopped and continuous flow XANES and EXAFS investigation  

NASA Astrophysics Data System (ADS)

The sequestration of sulfur and iron within sedimentary iron sulfides, and ultimately as pyrite, is a major sink in global biogeochemical cycles of those elements and has impacts on global carbon and oxygen cycles. The formation of the metastable black iron (II) monosulfide mackinawite is a key process because mackinawite forms in aqueous solutions where the Fe(II) and S(-II) IAP exceeds mackinawites Ksp. Mackinawite is the first formed iron sulfide phase, a consequence of Ostwalds step rule and is a reactant phase during the formation of thermodynamically stable sedimentary iron sulfide minerals such as pyrite. The reaction of dissolved Fe(II) and sulfide is extremely fast and reactions in the environmentally significant near-neutral pH range tend to completion in <1 second. We have combined stopped and continuous flow techniques with X-ray absorption spectroscopy to evaluate the products of the fast precipitation kinetics of mackinawite over millisecond timescales. EXAFS spectra and data collected during flow experiments were compared with those from a well characterised freeze-dried nanoparticulate mackinawite standard and with published data. Published work has used Rietveld crystal structure refinement to determine bond distances of 2.2558 and 2.5976 for Fe-S and Fe-Fe respectively. In our experiments Fe K edge XANES is consistent with tetrahedrally coordinated Fe in the precipitated sulfide phase. EXAFS data show that local Fe-S and Fe-Fe coordination and interatomic distances (Fe-S = 2.24; Fe-Fe = 2.57) are consistent with those determined for the standard mackinawite and published data. The coordination and spacing are developed in the precipitated phase after <10ms reaction at pH5, and considerably faster in experiments at near neutral to alkaline pH. No evidence for phases structurally intermediate between hexaqua Fe(II) and precipitated mackinawite was observed. Aqueous FeS cluster complexes previously identified as intermediates during mackinawite formation and iron sulfide mineral transformations did not contribute significantly to the EXAFS spectra collected. For environmental, geological and biogeochemical applications, the precipitation of the mineral mackinawite can be considered to proceed rapidly from aqueous Fe(II) and S(-II) ions to the nanoparticulate crystalline mineral. The materials labelled disordered mackinawite, or amorphous FeS phase which have been widely quoted in the iron sulfide literature do not form at any stage of the precipitation of mackinawite from aqueous solutions. Physical and chemical properties previously ascribed to an amorphous or disordered structure are a consequence of the nanoparticulate form of the first precipitated solid.

Butler, I. B.; Bell, A. M.; Charnock, J. M.; Rickard, D.; Vaughan, D. J.; Oldroyd, A.

2009-12-01

93

Effects of SiC volume fraction and aluminum particulate size on interfacial reactions in SiC nanoparticulate reinforced aluminum matrix composites  

Microsoft Academic Search

The SiC nanoparticulate reinforced Al3.0wt.% Mg composites were fabricated by combining pressureless infiltration with ball-milling and cold-pressing technology at 700C for 2h. The effects of SiC nanoparticulate volume fractions (6%, 10% and 14%) and Al particulate sizes (38?m and 74?m) on interfacial reactions were investigated by SEM, TEM and X-ray diffraction. The results show that the MgO at the interface

Bowen Xiong; Zhifeng Xu; Qingsong Yan; Baiping Lu; Changchun Cai

94

Nanoparticulate platinum(II) anticancer drug: synthesis and characterization of amphiphilic cyclotriphosphazene-platinum(II) conjugates.  

PubMed

Novel cyclotriphosphazene-platinum(II) conjugates were prepared by hydrolysis and platination of the amphiphilic cyclotriphosphazenes grafted with equimolar hydrophilic methoxy-poly(ethylene glycol) (MPEG) and hydrophobic oligopeptide. These macromolecular conjugates were found to form stable nanoparticles with a mean diameter of approximately 90-200 nm depending on the hydrophobicity of the conjugated (diamine)platinum moieties. The nanoparticulate platinum(II) conjugates have shown temperature and concentration dependent particle sizes. However, the particle sizes of the conjugates were found to decrease to a certain size as the solution concentration was decreased but remained stable even at 10 microM, which is enough for systemic delivery by injection. The conjugates exhibited lower in vitro cytotoxicity than cisplatin but reasonably good activity against selected human tumor cell lines. PMID:17709142

Yu, Ji Young; Jun, Yong Joo; Jang, Soo Hyun; Lee, Hwa Jeong; Sohn, Youn Soo

2007-07-16

95

Cardiac oxidative damage in mice following exposure to nanoparticulate titanium dioxide.  

PubMed

Nanoparticulate titanium dioxide (nano-TiO2 ) is a widely used powerful nanoparticulate material with high stability, anticorrosion, and photocatalytic property. However, it is possible that during nano-TiO2 exposure, there may be negative effects on cardiovascular system in intoxicated mice. The present study was therefore undertaken to determine nano-TiO2 -induced oxidative stress and to determine whether nano-TiO2 intoxication alters the antioxidant system in the mouse heart exposed to 2.5, 5, and 10 mg/kg body weight nano-TiO2 for 90 consecutive days. The findings showed that long-term exposure to nano-TiO2 resulted in obvious titanium accumulation in heart, in turn led to sparse cardiac muscle fibers, inflammatory response, cell necrosis, and cardiac biochemical dysfunction. Nano-TiO2 exposure promoted remarkably reactive oxygen species production such as superoxide radicals, hydrogen peroxide, and increased malondialdehyde, carbonyl and 8-OHdG levels as degradation products of lipid, protein, and DNA peroxidation in heart. Furthermore, nano-TiO2 exposure attenuated the activities of antioxidative enzymes, such as superoxide dismutase, ascorbate peroxidase, glutathione reductase, glutathione-S-transferase, and levels of antioxidants including ascorbic acid, glutathione, and thiol in heart. Therefore, TiO2 NPs exposure may impair cardiovascular system in mice, and attention should be aroused on the application of nano-TiO2 and their potential long-term exposure effects especially on human beings. 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 3238-3246, 2013. PMID:23553934

Sheng, Lei; Wang, Xiaochun; Sang, Xuezi; Ze, Yuguan; Zhao, Xiaoyang; Liu, Dong; Gui, Suxin; Sun, Qingqing; Cheng, Jie; Cheng, Zhe; Hu, Renping; Wang, Ling; Hong, Fashui

2013-04-02

96

Magnetic beads-based electrochemiluminescence immunosensor for determination of cancer markers using quantum dot functionalized PtRu alloys as labels.  

PubMed

A novel electrochemiluminescence (ECL) immunosensor for sensitive detection of human chorionic gonadotrophin antigen (HCG-Ag) was constructed using CdTe quantum dot functionalized nanoporous PtRu alloys (QDs@PtRu) as labels for signal amplification. In this paper, nanoporous PtRu alloy was employed as the carrier for immobilization of CdTe QDs and antibodies. Primary monoclonal antibody to alfa-HCG antigen (McAb(1)) was immobilized onto the surface of chitosan coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)/CS MNPs) by glutaraldehyde (GA) as coupling agent. Then McAb(1) could be easily separated and assembled on the surface of indium tin oxide glass (ITO) owing to their excellent magnetic properties with external magnetic forces holding the MNPs. Due to signal amplification from the high loading of CdTe QDs, 4.67-fold enhancements in ECL signal for HCG-Ag detection was achieved compared to the unamplified method (single QDs as labels). Under optimal conditions, a wide detection range (0.005~50 ng mL(-1)) and low detection limit (0.8 pg mL(-1)) were achieved through the sandwich-type immunosensor. The novel immunosensor showed high sensitivity and selectivity, excellent stability, and good reproducibility, and thus has great potential for clinical detection of HCG-Ag. In particular, this approach presents a novel class of combining bifunctional nanomaterials with preferable ECL properties and excellent magnetism, which suggests considerable potential in a wide range of applications for bioassays. PMID:22421801

Zhang, Yan; Ge, Shenguang; Wang, Shaowei; Yan, Mei; Yu, Jinghua; Song, Xianrang; Liu, Weiyan

2012-03-15

97

Generation of Oxidants From the Reaction of Nanoparticulate Zero-Valent Iron and Oxygen for the use in Contaminant Remediation  

Microsoft Academic Search

The reaction of zero-valent iron (ZVI) with oxygen can lead to the formation of oxidants, which may be used to transform recalcitrant contaminants including non-polar organics and certain metals. Nanoparticulate iron might provide a practical mechanism of remediating oxygen-containing groundwater and contaminated soil. To gain insight into the reaction mechanism and to quantify the yield of oxidants, experiments were performed

C. R. Keenan; C. Lee; D. L. Sedlak

2007-01-01

98

A novel CO-tolerant PtRu coreshell structured electrocatalyst with Ru rich in core and Pt rich in shell for hydrogen oxidation reaction and its implication in proton exchange membrane fuel cell  

Microsoft Academic Search

A novel PtRu catalyst consisting of a Ru-rich core and a Pt-rich shell was synthesized using a two-step microwave irradiation technique. The synthesized PtRu\\/C catalysts were characterized by X-ray diffraction (XRD), extended X-ray absorption finestructure (EXAFS), transmission electron microscopy (TEM) as well as energy dispersive X-ray spectrometry (EDXS). The produced PtRu\\/C catalysts showed identical crystalline structure and diffraction peaks to

Lei Zhang; Jenny Kim; Hao Ming Chen; Feihong Nan; Karleen Dudeck; Ru-Shi Liu; Gianluigi A. Botton; Jiujun Zhang

2011-01-01

99

Double-coated poly (butylcynanoacrylate) nanoparticulate delivery systems for brain targeting of dalargin via oral administration.  

PubMed

The aim of this study is to evaluate oral administration of poly (butylcyanoacrylate) nanoparticulate delivery systems (PBCA-NDSs), double-coated with Tween 80 and poly (ethylene) glycol (PEG) 20000 for brain delivery of hexapeptide dalargin, an anti-nociceptive peptide that does not cross blood-brain barrier (BBB) by itself. Studies have proven the brain uptake of Tween 80 overcoated nanoparticles after intravenous administration, but studies for brain delivery of nanoparticles after oral administration had been limited due to reduced bioavailability of nanoparticles and extensive degradation of the peptide and/or nanoparticles by gastrointestinal enzymes. To address this problem, dalargin-loaded PBCA-NDS were successively double-coated with Tween 80 and PEG 20000 in varied concentrations of up to 2% each. Measurement of in vivo central anti-nociceptive effect of dalargin along with a dose response curve was obtained by the tail flick test following the oral administration of PBCA-NDSs to mice. Results from the tail flick test indicated that significant dalargin-induced analgesia was observed from PBCA-NDSs with double-coating of Tween and PEG in comparison with single-coating of either Tween or PEG. Hence, it could be concluded that surface coated PBCA-NDS can be used successfully for brain targeting of dalargin or other peptides administered orally. However, further studies are required to elucidate the exact transport mechanism of PBCA-NDSs from gastrointestinal tract to brain. PMID:15858853

Das, Debanjan; Lin, Senshang

2005-06-01

100

Effects of chronic nanoparticulate silver exposure to adult and juvenile sheepshead minnows (Cyprinodon variegatus).  

PubMed

The use of nanoparticulate silver (AgNP) is increasingly widespread and recently has been shown to have a plausible release route into aquatic environments. To date, relatively little research has examined the effects of AgNP on estuarine fish. The authors present data indicating that chronic exposure to low levels of AgNP induces significant adverse effects in both juvenile and adult sheepshead minnows (Cyprinodon variegarus; SHMs). Chronic exposure to low levels of AgNP produced significant increases in tissue burdens in both juvenile and adult SHMs, resulting in significant thickening of epithelia gill tissue and in dramatically altered gene expression profiles. The results do not appear to be attributable to the release of silver ions through particle dissolution. The alteration in gene expression was greatest in adult gonads, but no evidence of AgNP-related dysfunction was found at the tissue level. In contrast, the authors found a significant effect on gill morphology, but very little evidence of effect on gill transcription profiles. PMID:21994144

Griffitt, Robert J; Brown-Peterson, Nancy J; Savin, Daniel A; Manning, C Steve; Boube, Idrissa; Ryan, R A; Brouwer, Marius

2012-01-01

101

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

SciTech Connect

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.

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

2006-01-01

102

Synthesis and characterization of nanoparticulate MnS within the pores of mesoporous silica  

SciTech Connect

Mesoporous silica was loaded with nanoparticulate MnS via a simple post-synthesis treatment. The mesoporous material that still contained surfactant was passivated to prevent MnS formation at the surface. The surfactant was extracted and a novel manganese ethylxanthate was used to impregnate the pore network. This precursor thermally decomposes to yield MnS particles that are smaller or equal to the pore size. The particles exhibit all three common polymorphs. The passivation treatment is most effective at lower loadings because at the highest loadings (SiO{sub 2}:MnS molar ratio of 6:1) large particles (>50 nm) form at the exterior of the mesoporous particles. The integrity of the mesoporous network is maintained through the preparation and high order is maintained. The MnS particles exhibit unexpected ferromagnetism at low temperatures. Strong luminescence of these samples is observed and this suggests that they may have a range of important application areas. - Graphical abstract: A novel manganese ethylxanthate precursor was used to impregnate the pore network of mesoporous silica and was decomposed to yield MnS particles smaller or equal to the pore size. The particles exhibit all three common polymorphs, demonstrate unexpected ferromagnetism at low temperatures and display a strong luminescence.

Barry, Louse; Copley, Mark [Department of Chemistry, University College Cork, Cork (Ireland); Holmes, Justin D. [Department of Chemistry, University College Cork, Cork (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Otway, David J. [Department of Chemistry, University College Cork, Cork (Ireland); Kazakova, Olga [National Physical Laboratory, Teddington (United Kingdom); Morris, Michael A. [Department of Chemistry, University College Cork, Cork (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland)], E-mail: m.morris@ucc.ie

2007-12-15

103

Cytotoxic responses and potential respiratory health effects of carbon and carbonaceous nanoparticulates in the Paso del Norte airshed environment.  

PubMed

We have utilized a range of manufactured or commercial nanoparticulate materials, including surrogate carbon nano-PM along with combustion-generated carbonaceous (soot) nano-PM characteristic of environmental nano- PM (both indoor and outdoor) to investigate and compare their cytotoxic response in vitro with an immortalized human epithelial (lung model) cell line (A549). These have included nano-Ag, Al2O3, TiO2, Fe2O3, ZrO2, Si3N4, chrysotile asbestos, BC, 2 types of MWCNT-aggregate PM (MWCNT-R and MWCNT-N), and high-volume glass fiber collected soots: candle, wood, diesel (truck), tire, and 3-types of natural gas kitchen burner-generated soots: yellow (fuel-rich) flame, low-flow blue flame, and normal flow blue flame soot PM. These carbonaceous nano-PM species can be found in either the indoor and outdoor environments or microenvironments. Two-day and two-week in-vitro cultures of A549 showed cell death (or decreased cell viability) for all nanoparticulate materials, but especially significant for all but the TiO2 and candle, wood, and diesel PM. The natural gas kitchen burner combustion PM cell death response was characteristic of BC and MWCNT PM. There was no correlation with total PAH content of the soot PM. Cytokine release (IL-6, IL-8) was detected for the Ag, Fe2 O3, asbestos, BC and the MWCNT PM. Reactive oxygen species (ROS) production was also detected for Ag, Fe2 O3, ZrO2, asbestos, BC, and the MWCNT aggregate PM, as well as the natural gas kitchen burner combustion PM. TEM, FESEM, and optical microscopy examination of these nanomaterials illustrate the wide range in PM morphologies and crystallinities as well as cell morphologies. Taken together, these results illustrate proinflammatory and related respiratory health issues in relation to environmental nanoparticulates. PMID:18441401

Soto, K F; Murr, L E; Garza, K M

2008-03-01

104

Inkjet-printed gold nanoparticulate patterns for surface finish in electronic package  

NASA Astrophysics Data System (ADS)

Gold (Au) pads for surface finish in electronic package were developed by the inkjet printing method. The Au ink for printing was prepared by Au nanoparticles (NPs) coated with capping molecules of dodecylamine (C12H25NH2). The microstructures of the inkjet-printed Au films were characterized after sintering in various gas flows. The film sintered in air showed that bonding between NPs was not enough for further grain growth due to the incomplete decomposition of the capping layer. The film sintered under nitrogen (N2) had NPs existing on the surface and the bottom which did not participate in sintering. When the film was sintered under N2-bubbled through formic acid (FA/N2), a large portion of the pores were observed to make a holey pancake-like structure of the film. The microstructures of the inkjet-printed Au film became denser with grain growth when Au NPs were sintered under mixed gas flows of FA/N2 and N2. The resistivity of film was 4.79 ?? cm, about twice the bulk value. Organic analysis showed that about 0.43% of residual organics was left in the film. Therefore, this Au film was chosen for solder ball shear test because the microstructure was denser compared to the films sintered under other gasses such as N2 or FA/N2 and less organic residue was found from organic analyses. Even though the film sintered under N2 showed the best electrical property (4.35 ?? cm), it was not adopted in the shear test because NPs remaining on the bottom of the film could lead to the poor adhesion between the film and substrate and show low shear strength. The shear force was 8.04 newton (N) on average and the strength was 64 MPa. This shear strength is good enough to substitute the inkjet-printed Au nanoparticulate film for electroplating in electronic package.

Jang, Seonhee; Cho, Hyejin; Kang, Seongkoo; Oh, Sungil; Kim, Donghoon

2011-11-01

105

Performance of PtPd electrocatalysts in direct methanol fuel cell.  

PubMed

PtPd nanoparticles on carbon black were prepared to investigate the role of Pd in the anode and cathode of a direct methanol fuel cell (DMFC). The PtPd catalysts in the anode showed a significantly lower performance than the PtRu catalyst. However, the cell performances of these catalysts in the cathode were comparable to that of the Pt catalyst. From cyclic voltammetry, it was observed that the Pd with the Pt catalyst lowered the peak potential and increased the coulombic charge for oxide reduction on the surface of the catalyst. Also, the Pd catalyst without Pt showed relatively high activity for oxygen reduction reaction. PMID:20359018

Kim, In-Tae; Choi, Mahnsoo; An, Jung-Chul; Lee, Hong-Ki; Shim, Joongpyo

2010-05-01

106

Electrodeposited nanoporous versus nanoparticulate ZnO films of similar roughness for dye-sensitized solar cell applications.  

PubMed

We present a comparative study of two different ZnO porous film morphologies for dye-sensitized solar cell (DSSC) fabrications. Nanoparticulate ZnO was prepared by the doctor-blade technique starting from a paste containing ZnO nanoparticles. Nanoporous ZnO films were grown by a soft template-assisted electrochemical growth technique. The film thicknesses were adjusted at similar roughness of about 300 in order to permit a worthy comparison. The effects on the cell performances of sensitization by dyes belonging to three different families, namely, xanthene (eosin Y) and indoline (D102, D131, D149 and D205) organic dyes as well as a ruthenium polypyridine complex (N719), have been investigated. The mesoporous electrodeposited matrix exhibits significant morphological changes upon the photoanode preparation, especially upon the dye sensitization, that yield to a dramatic change of the inner layer morphology and increase in the layer internal specific surface area. In the case of indoline dyes, better efficiencies were found with the electrodeposited ZnO porous matrixes compared to the nanoparticulate ones, in spite of significantly shorter electron lifetimes measured by impedance spectroscopy. The observation is interpreted in terms of much shorter transfer time in the oxide in the case of the electrodeposited ZnO films. Among the tested dyes, the D149 and D205 indoline organic dyes with a strong acceptor group were found the most efficient with the best cell over 4.6% of overall conversion efficiency. PMID:21082820

Guerin, V M; Magne, C; Pauport, Th; Le Bahers, T; Rathousky, J

2010-11-17

107

Effect of adsorbed extracellular polymeric substances (EPS) on colloidal mobility of nanoparticulate iron oxides  

NASA Astrophysics Data System (ADS)

Solubility and transport of nutrients and pollutants is affected by the presence of colloidal nanoparticles (CNP) which may act as mobile geosorbents. In soils and aquifers, pure and organically modified Fe- and Mn-oxy-hydroxides are of particular importance due to their ubiquitous presence and also due to their progressive use for environmental cleanup. Stability and aggregation behavior control the mobility of CNP and depend on pH, ionic strength, and the presence of monovalent or divalent anions. In natural environments, however, iron oxides are usually covered by organic matter. Such coverage will completely change the colloidal surface properties and impose additional control on the colloidal mobility. Important sources for natural organic coatings are extracellular polymeric substances (EPS), i.e., complex mixtures of biopolymers consisting of polysaccharides and proteins and variable amounts of lipids and nucleic acids. The objective of our study was to quantify the effect of EPS coatings on the colloidal stability, mobility and reactivity of hematite by column experiments. Columns (10 cm 5 cm) were filled with glass beads (0.25 mm ) as porous medium and operated in sterile closed flow conditions. Nanoparticulate hematite was coated to different degrees by extracellular polymeric substances (EPS) extracted from, liquid cultures of Bacillus subtillis. The pH was kept constant at 7. The hematite particles exhibited increasing colloidal stability with increasing amounts of EPS. Critical colloidal concentration (CCC) of the particles increased from 95 mM NaCl for uncoated particles to 250 mM NaCl for coated particles. EPS coated hematite did not react with the porous medium and stayed mobile while the uncoated hematite was immobile due to adsorption to the glass beads. Also colloidally unstable hematite particles did not show any mobility. Thus the organic coatings enhanced the colloidal stability, which consecutively increased the mobility of the particles. Also, the reactivity of these particles to the porous medium is reduced due to the masking of the reactive hematite surface sites with EPS. EPS coated CNP may define the major part of mobile material in natural environments like soils, sediments and aquifers.

Pradip Narvekar, Sneha; Totsche, Kai Uwe

2013-04-01

108

Development of a nanoparticulate formulation of retinoic acid that suppresses Th17 cells and upregulates regulatory T cells  

PubMed Central

Retinoic acid (RA) is a small molecule capable of shunting developing T cells away from the Th17 lineage and towards the Treg phenotype, making it a potentially useful therapeutic for autoimmune and inflammatory diseases. However, therapy can be complicated by systemic toxicity and unpredictable bioavailability, making a targeted drug delivery vehicle for local therapy desirable. A promising approach is the use of nanoparticles, which have been demonstrated to increase potency and decrease toxicity of therapies in a variety of disease models including Th17 mediated diseases. Nanoparticles can also be targeted to specific cell types via surface modification, further increasing the potential specificity of this approach. We therefore constructed a nanoparticulate drug delivery platform from poly(lactic-co-glycolic acid) (PLGA) capable of encapsulating and releasing RA. Here we report the fabrication, characterization, and in vitro bioactivity of this platform. We demonstrate that RA containing PLGA nanoparticles suppress IL-17 production and ROR-?(t) expression in T cells polarized towards the Th17 phenotype in vitro with similar potency to that of free drug. Furthermore, we show that these particles enhance TGF-? dependent Foxp3 expression and IL-10 production of T cells in vitro with similar potency to free RA. Finally, we demonstrate that T cells polarized towards the Th17 phenotype in the presence of free and nanoparticulate RA have similarly suppressed ability to induce IL-6 production by fibroblasts. Our findings demonstrate the feasibility of RA delivery via biodegradable nanoparticles and represent an exciting technology for the treatment of autoimmune and inflammatory diseases.

Jeanbart, Laura; Nowyhed, Heba; Abraham, Clara; Craft, Joe

2010-01-01

109

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

Microsoft Academic Search

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

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

2009-01-01

110

Influence of different buffer solutions on the performance of anodic Pt-Ru\\/C nanoparticle electrocatalysts for a direct methanol fuel cell  

Microsoft Academic Search

This research aims to improve the activity of Pt-Ru nanoparticle electrocatalysts and thus, to lower the catalyst loading in anodes for methanol electrooxidation. The direct methanol fuel cell (DMFC) anodic Pt-Ru\\/C nanoparticle electrocatalysts were prepared using a chemical reduction method. The pH values of the reductive solutions were adjusted by different buffer solutions of CH3COONaNaOH, C6H5Na3O7NaOH, and Na2CO3NaHCO3, respectively. The

Zhen-Bo Wang; Ge-Ping Yin; Peng-Fei Shi; Bo-Qian Yang; Peter-Xian Feng

2007-01-01

111

Design and assembly of solid-phases for the effective recovery of nanoparticulate bioproducts in fluidised bed contactors.  

PubMed

Practical recovery of nanoparticulate bioproducts from suspension feedstocks has been studied in batch, fixed bed and fluidised bed adsorptive contactors. The performance of five discrete configurations of adsorbent solid phase has been critically evaluated in the anion exchange recovery of mg quantities of BSA nanoparticles. These have served as surrogate size mimics of less easily sourced viral and plasmid gene therapy vectors, characterised by high value and a shortage of supply in quantities sufficient for research and development. Performance parameters of binding capacity, efficacy of washing, desorption efficiency and total cycle time were strongly influenced by the external and internal topographies of solid phases, together with the localised concentrations of interacting chemical ligands which modulate adsorption. In respect of a full operational recovery cycle, porous adsorbents developed for refined chromatographic fractionation of macromolecules, appear less suited overall than solid, nonporous particles, or solid particles coated with a shallow pellicle of active adsorbent material. Such findings have been confirmed in a detailed demonstration of the recovery of plasmid DNA (7.8 Kb) from chemical lysates of Escherichia coli. PMID:11787793

Zhang, Z; Burton, S; Williams, S; Thwaites, E; Lyddiatt, A

2001-01-01

112

Preparation and characterization of Pt\\/C and Pt Ru\\/C electrocatalysts for direct ethanol fuel cells  

Microsoft Academic Search

Nano-sized Pt and PtRu colloids are prepared by a microwave-assisted polyol process, and transferred to a toluene solution of decanthiol. Vulcan XC-72 is then added to the toluene solution to adsorb the thiolated Pt and PtRu colloids. Transmission electron microscopy examinations show nearly spherical particles and narrow size distributions for both supported and unsupported metals. The carbon-supported Pt and PtRu

Zhaolin Liu; Xing Yi Ling; Xiaodi Su; Jim Yang Lee; Leong Ming Gan

2005-01-01

113

Natural and anthropogenic environmental nanoparticulates: Their microstructural characterization and respiratory health implications  

Microsoft Academic Search

A wide range of environmental particulate matter (PM) both indoor and outdoor and consisting of natural and anthropogenic PM was collected by high volume air filters, electrostatic precipitation, and thermophoretic precipitation directly onto transmission electron microscope (TEM) coated grid platforms. These collected PM have been systematically characterized by TEM, energy-dispersive X-ray spectrometry (EDS) and scanning electron microscopy (SEM). In the

L. E. Murr; K. M. Garza

2009-01-01

114

Chemoprevention of pancreatic cancer using solid-lipid nanoparticulate delivery of a novel aspirin, curcumin and sulforaphane drug combination regimen  

PubMed Central

Pancreatic cancer is the fourth largest cause of cancer deaths in the Unites States and the prognosis is grim with <5% survival chances upon diagnosis. The objective of this study was to assess the combined chemopreventive effect of solid lipid nanoparticle (SLN) encapsulated drugs aspirin (ASP), curcumin (CUR) and free sulforaphane (SFN) for the chemoprevention of pancreatic cancer. Experiments were carried out (1) to evaluate the feasibility of encapsulation of these chemopreventive agents within solid lipid systems and (2) to measure the synergistic effects of a combination of ASP with CUR in SLNs mixed with free SFN against cell proliferation and apoptosis in pancreatic cancer cells, MIA PaCa-2 and Panc-1. The SLNs were prepared using a modified solvent evaporation technique and were characterized for particle sizing, encapsulation efficiency and drug release. ASP and CUR SLNs were formulated within the particle size range of 150250 nm and were found to have an encapsulation efficiency of 85 and 69%, respectively. Sustained release of drugs over a 96 h period from SLNs was observed. The SLNs were stable over a 3-month storage period at room temperature. Cell viability studies demonstrated that combinations of low doses of ASP SLN (25 ?M), CUR SLN (2.5 ?M) and free SFN (5 ?M) significantly reduced cell viability by 43.6 and 48.49% in MIAPaca-2 and Panc-1 cell lines, respectively. Furthermore, increased apoptosis of 61.3 and 60.37% was found in MIA Paca-2 and Panc-1 cell lines, respectively, in comparison to the individual doses administered. Synergistic effects were demonstrated using MTS and apoptosis assays. Thus, this study successfully demonstrated the feasibility of using a solid lipid nanoparticulate system for the first time to deliver this novel combination chemoprevention regimen, providing valuable evidence for the usability of nanotechnology-based drug regimens towards pancreatic cancer chemoprevention.

SUTARIA, DHRUVITKUMAR; GRANDHI, BALAGANGADHAR KARTHIK; THAKKAR, ARVIND; WANG, JEFFREY; PRABHU, SUNIL

2012-01-01

115

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

PubMed

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

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

116

Osteogenic and antimicrobial nanoparticulate calcium phosphate and poly-(D,L-lactide-co-glycolide) powders for the treatment of osteomyelitis.  

PubMed

Development of a material for simultaneous sustained and localized delivery of antibiotics and induction of spontaneous regeneration of hard tissues affected by osteomyelitis stands for an important clinical need. In this work, a comparative analysis of the bacterial and osteoblastic cell response to two different nanoparticulate carriers of clindamycin, an antibiotic commonly prescribed in the treatment of bone infection, one composed of calcium phosphate and the other comprising poly-(D,L-lactide-co-glycolide)-coated calcium phosphate, was carried out. Three different non-cytotoxic phases of calcium phosphate, exhibiting dissolution and drug release profiles in the range of one week to two months to one year, respectively, were included in the analysis: monetite, amorphous calcium phosphate and hydroxyapatite. Spherical morphologies and narrow size distribution of both types of nanopowders were confirmed in transmission and scanning electron microscopic analyses. The antibiotic-containing powders exhibited sustained drug release contingent upon the degradation rate of the carrier. Assessment of the antibacterial performance of the antibiotic-encapsulated powders against Staphylococcus aureus, the most common pathogen isolated from infected bone, yielded satisfactory results both in broths and on blood agar plates for all the analyzed powders. In contrast, no cytotoxic behavior was detected upon the incubation of the antibiotic powders with the osteoblastic MC3T3-E1 cell line for up to three weeks. The cells were shown to engage in a close contact with the antibiotic-containing particles, irrespective of their internal or surface phase composition, polymeric or mineral. At the same time, both types of particles upregulated the expression of osteogenic markers osteocalcin, osteopontin, Runx2 and protocollagen type I, suggesting their ability to promote osteogenesis and enhance remineralization of the infected site in addition to eliminating the bacterial source of infection. PMID:23706222

Uskokovi?, Vuk; Hoover, Charles; Vukomanovi?, Marija; Uskokovi?, Dragan P; Desai, Tejal A

2013-04-13

117

A Novel Nanoparticulate Formulation of Arsenic Trioxide with Enhanced Therapeutic Efficacy in a Murine Model of Breast Cancer  

PubMed Central

Purpose The clinical success of arsenic trioxide (As2O3) in hematological malignancies has not been replicated in solid tumors due to poor pharmacokinetics and dose-limiting toxicity. We have developed a novel nanoparticulate formulation of As2O3 encapsulated in liposomal vesicles or nanobins [(NB(Ni,As)] to overcome these hurdles. We postulated that nanobin encapsulation of As2O3 would improve its therapeutic index against clinically aggressive solid tumors, such as triple negative breast carcinomas. Experimental Design The cytotoxicity of NB(Ni,As), the empty nanobin, and free As2O3 was evaluated against a panel of human breast cancer cell lines. The plasma pharmacokinetics of NB(Ni,As) and free As2O3 were compared in rats to measure drug exposure. In addition, the antitumor activity of these agents was evaluated in an orthotopic model of human triple negative breast cancer. Results The NB(Ni,As) agent was much less cytotoxic in vitro against a panel of human breast cancer cell lines than free As2O3. In contrast, NB(Ni,As) dramatically potentiated the therapeutic efficacy of As2O3 in vivo in an orthotopic model of triple negative breast cancer. Reduced plasma clearance, enhanced tumor uptake, and induction of tumor cell apoptosis were observed for NB(Ni,As). Conclusions Nanobin encapsulation of As2O3 improves the pharmacokinetics and antitumor efficacy of this cytotoxic agent in vivo. Our findings demonstrate the therapeutic potential of this nanoscale agent and provide a foundation for future clinical studies in breast cancer and other solid tumors.

Ahn, Richard W.; Chen, Feng; Chen, Haimei; Stern, Stephan T.; Clogston, Jeffrey D.; Patri, Anil K.; Raja, Meera R.; Swindell, Elden P.; Parimi, Vamsi; Cryns, Vincent L.; O'Halloran, Thomas V.

2010-01-01

118

1-(3'-amino)propylsilatrane derivatives as covalent surface linkers to nanoparticulate metal oxide films for use in photoelectrochemical cells  

NASA Astrophysics Data System (ADS)

A triethanolamine-protected silane, 1-(3'-amino)propylsilatrane, was incorporated into the structure of porphyrin- and ruthenium-based dyes and used to link them to transparent semiconductor nanoparticulate metal oxide films. Silatrane reacts with the metal oxide to form strong, covalent silyl ether bonds. In this study, silatrane-functionalized dyes and analogous carboxylate-functionalized dyes were used as visible light sensitizers for porous nanoparticulate SnO2 photoanodes. The performance of the dyes was compared in photoelectrochemical cells incorporating either non-regenerative or regenerative redox components. The non-regenerative cell used NADH (?-nicotinamide adenine dinucleotide) as a sacrificial electron donor and Hg2SO4/Hg as a sacrificial cathode, whereas the regenerative cell used the iodide/triiodide redox couple. Experiments showed that the silyl ether bonding gave the electrodes increased stability toward sensitizer desorption compared to carboxylate surface linkages. Porphyrin-silatrane dyes also demonstrated similar or better performance than their carboxylate analogs in photoelectrochemical cells. The improvement correlates with the results from transient absorbance spectroscopy, which show that the longer linker on the silatrane porphyrins slows charge recombination between oxidized porphyrin and the electrode surface. The improved photoelectrochemical cell efficiency and stability of the silatrane-based dyes compared to carboxylates demonstrate that silatranes are promising agents for bonding organic molecules to metal oxide surfaces.

Brennan, Bradley J.; Keirstead, Amy E.; Liddell, Paul A.; Vail, Sean A.; Moore, Thomas A.; Moore, Ana L.; Gust, Devens

2009-12-01

119

Patterning of nanoparticulate transparent conductive ITO films using UV light irradiation and UV laser beam writing  

NASA Astrophysics Data System (ADS)

Indium tin oxide (ITO) thin film is one of the most widely used as transparent conductive electrodes in all forms of flat panel display (FPD) and microelectronic devices. Suspension of already crystalline conductive ITO nanoparticles fully dispersed in alcohol was spun, after modifying with coupling agent, on glass substrates. The low cost, simple and versatile traditional photolithography process without complication of the photoresist layer was used for patterning ITO films. Using of UV light irradiation through mask and direct UV laser beam writing resulted in an accurate linear, sharp edge and very smooth patterns. Irradiated ITO film showed a high transparency (85%) in the visible region. The electrical sheet resistance decrease with increasing time of exposure to UV light and UV laser. Only 5 min UV light irradiation is enough to decrease the electrical sheet resistance down to 5 k??.

Solieman, A.; Moharram, A. H.; Aegerter, M. A.

2010-01-01

120

Catalyst inks and method of application for direct methanol fuel cells  

DOEpatents

Inks are formulated for forming anode and cathode catalyst layers and applied to anode and cathode sides of a membrane for a direct methanol fuel cell. The inks comprise a Pt catalyst for the cathode and a Pt--Ru catalyst for the anode, purified water in an amount 4 to 20 times that of the catalyst by weight, and a perfluorosulfonic acid ionomer in an amount effective to provide an ionomer content in the anode and cathode surfaces of 20% to 80% by volume. The inks are prepared in a two-step process while cooling and agitating the solutions. The final solution is placed in a cooler and continuously agitated while spraying the solution over the anode or cathode surface of the membrane as determined by the catalyst content.

Zelenay, Piotr (Los Alamos, NM); Davey, John (Los Alamos, NM); Ren, Xiaoming (Los Alamos, NM); Gottesfeld, Shimshon (Los Alamos, NM); Thomas, Sharon C. (Vancouver, CA)

2004-02-24

121

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

SciTech Connect

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.

Zalk, D; Paik, S; Swuste, P

2009-01-27

122

Occurrence and behaviour of dissolved, nano-particulate and micro-particulate iron in waste waters and treatment systems: new insights from electrochemical analysis.  

PubMed

Cyclic-, Differential Pulse- and Steady-state Microdisc Voltammetry (CV, DPV, SMV) techniques have been used to quantify the occurrence and fate of dissolved Fe(ii)/Fe(iii), nano-particulate and micro-particulate iron over a 12 month period in a series of net-acidic and net-alkaline coal mine drainages and passive treatment systems. Total iron in the mine waters is typically 10-100 mg L(-1), with values up to 2100 mg L(-1). Between 30 and 80% of the total iron occurs as solid phase, of which 20 to 80% is nano-particulate. Nano-particulate iron comprises 20 to 70% of the nominally "dissolved" (i.e. <0.45 ?m) iron. Since coagulation and sedimentation are the only processes required to remove solid phase iron, these data have important implications for the generation or consumption of acidity during water treatment. In most waters, the majority of truly dissolved iron occurs as Fe(ii) (average 64 22%). Activities of Fe(ii) do not correlate with pH and geochemical modelling shows that no Fe(ii) mineral is supersaturated. Removal of Fe(ii) must proceed via oxidation and hydrolysis. Except in waters with pH < 4.4, activities of Fe(iii) are strongly and negatively correlated with pH. Geochemical modelling suggests that the activity of Fe(iii) is controlled by the solubility of hydrous ferric oxides and oxyhydroxysulfates, supported by scanning and transmission electron microscopic analysis of solids. Nevertheless, the waters are generally supersaturated with respect to ferrihydrite and schwertmannite, and are not at redox equilibrium, indicating the key role of oxidation and hydrolysis kinetics on water treatment. Typically 70-100% of iron is retained in the treatment systems. Oxidation, hydrolysis, precipitation, coagulation and sedimentation occur in all treatment systems and - independent of water chemistry and the type of treatment system - hydroxides and oxyhydroxysulfates are the main iron sinks. The electrochemical data thus reveal the rationale for incomplete iron retention in individual systems and can thus inform future design criteria. The successful application of this low cost and rapid electrochemical method demonstrates its significant potential for real-time, on-site monitoring of iron-enriched waters and may in future substitute traditional analytical methods. PMID:22370608

Matthies, R; Aplin, A C; Horrocks, B R; Mudashiru, L K

2012-02-27

123

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

SciTech Connect

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.

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

2009-12-14

124

Enhanced electron extraction from template-free 3D nanoparticulate transparent conducting oxide (TCO) electrodes for dye-sensitized solar cells.  

PubMed

The semiconducting metal oxide-based photoanodes in the most efficient dye-sensitized solar cells (DSSCs) desires a low doping level to promote charge separation, which, however, limits the subsequent electron extraction in the slow diffusion regime. These conflicts are mitigated in a new photoanode design that decouples the charge separation and extraction functions. A three-dimensional highly doped fluorinated SnO(2) (FTO) nanoparticulate film serves as conductive core for low-resistance and drift-assisted charge extraction while a thin, low-doped conformal TiO(2) shell maintains a large resistance to recombination (and therefore long charge lifetime). EIS reveals that the electron transit time is reduced by orders of magnitude, whereas the recombination resistance remains in the range of traditional nanoparticle TiO(2) photoelectrodes. PMID:22834639

Yang, Zhenzhen; Gao, Shanmin; Li, Tao; Liu, Fa-Qian; Ren, Yang; Xu, Tao

2012-08-03

125

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

PubMed

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

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

2013-09-17

126

Nanoparticulated heat-stable (STa) and heat-labile B subunit (LTB) recombinant toxin improves vaccine protection against enterotoxigenic Escherichia coli challenge in mouse.  

PubMed

Enterotoxigenic Escherichia coli (ETEC) remains a major cause of diarrheic disease in developing areas, for which there is no effective vaccine available. In this study, we genetically engineered a recombinant heat-stable enterotoxin (STa) coupled to the subunit B of heat-labile enterotoxin (LTB). This fusion protein, STa-LTB, possesses a single amino acid substitution at position 14 of STa. Our data demonstrates that the enterotoxicity of STa in STa-LTB was dramatically reduced. A gelatin nanovaccine candidate was prepared using the purified STa-LTB fusion protein characterized with an entrapment efficiency of 84.886.37% and smooth spheres size ranges of 80-200nm. Antigen-specific antibody responses against STa-LTB and STa in the sera and the intestinal mucus respectively were used to test the immunogenicity of the nanovaccine. This vaccine was further screened in mice by its ability to elicit neutralizing antibodies against STa and protect animals from the challenge with ETEC in mice. The STa-LTB nanoparticles delivered demonstrated a capacity to induce significantly higher and long-lasting antibody responses and increased immune protection against ETEC challenge relative to the control STa-LTB vaccine absorbed in conventional aluminum hydrate salt (p<0.01). These results warrant the further studies of the development of a novel nanoparticulate vaccine as a broad-spectrum vaccine against ETEC infection. PMID:23040995

Deng, Guangcun; Zeng, Jin; Jian, Minjie; Liu, Wenmiao; Zhang, Zhong; Liu, Xiaoming; Wang, Yujiong

2012-10-05

127

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

PubMed

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 TiO(2) 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. TiO(2) 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 TiO(2). Electron microscopy analysis and impedance measurements showed that a thin continuous TiO(2) layer is formed at the interface as a result of the local melting of TiO(2) 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 TiO(2) paste revealed an efficiency improvement from eta = 3.3% to 5.4%, and an increase from 8.2% to 11.2% was achieved with the TiO(2) electrodes made from a commercial paste. PMID:20671364

Kim, Jinsoo; Kim, Jonghyun; Lee, Myeongkyu

2010-07-30

128

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

NASA Astrophysics Data System (ADS)

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.

Kim, Jinsoo; Kim, Jonghyun; Lee, Myeongkyu

2010-08-01

129

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

PubMed Central

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.

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

2013-01-01

130

Pd and PtRu anode electrocatalysts supported on multi-walled carbon nanotubes and their use in passive and active direct alcohol fuel cells with an anion-exchange membrane (alcohol = methanol, ethanol, glycerol)  

Microsoft Academic Search

Palladium and platinumruthenium nanoparticles supported on multi-walled carbon nanotubes (MWCNT) are prepared by the impregnation-reduction procedure. The materials obtained, Pd\\/MWCNT and PtRu\\/MWCNT, are characterized by TEM, ICP-AES and XRPD. Electrodes coated with Pd\\/MWCNT are scrutinized for the oxidation of methanol, ethanol or glycerol in 2M KOH solution in half cells. The catalyst is very active for the oxidation of all

Valentina Bambagioni; Claudio Bianchini; Andrea Marchionni; Jonathan Filippi; Francesco Vizza; Jacques Teddy; Philippe Serp; Mohammad Zhiani

2009-01-01

131

Design, development, and demonstration of a fully LabVIEW controlled in situ electrochemical Fourier transform infrared setup combined with a wall-jet electrode to investigate the electrochemical interface of nanoparticulate electrocatalysts under reaction conditions.  

PubMed

We present a detailed description of the construction of an in situ electrochemical ATR-FTIR setup combined with a wall-jet electrode to investigate the electrocatalytic properties of nanoparticulate catalysts in situ under controlled mass transport conditions. The presented setup allows the electrochemical interface to be probed in combination with the simultaneous determination of reaction rates. At the same time, the high level of automation allows it to be used as a standard tool in electrocatalysis research. The performance of the setup was demonstrated by probing the oxygen reduction reaction on a platinum black catalyst in sulfuric electrolyte. PMID:23902087

Nesselberger, Markus; Ashton, Sean J; Wiberg, Gustav K H; Arenz, Matthias

2013-07-01

132

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

Abstract 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

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

2013-07-02

133

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

NASA Astrophysics Data System (ADS)

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 90C. 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.

Xiong, Liufeng

134

Nanoparticulate material delivery to plants  

Microsoft Academic Search

The successful application of various nanoplatforms in medicine under in vitro conditions has generated some interest in agri-nanotechnology. This technology holds the promise of controlled release of agrochemicals and site targeted delivery of various macromolecules needed for improved plant disease resistance, efficient nutrient utilization and enhanced plant growth. Processes such as nanoencapsulation show the benefit of more efficient use and

Remya Nair; Saino Hanna Varghese; Baiju G. Nair; T. Maekawa; Y. Yoshida; D. Sakthi Kumar

2010-01-01

135

Elementary processes at nanoparticulate photocatalysts  

NASA Astrophysics Data System (ADS)

The paper is a mini review on the authors own work related to laser induced processes at metal nanoparticle/oxidic support systems. A number of aspects will be addressed ranging from the nano particle size dependence on the efficiency of the photochemical process, the influence of low coordination sites of the nano particles and dynamical processes such as energy transfer between adsorbates, light induced particle changes or spill over processes. The paper reviews nano and femtosecond laser experiments as well as quantum state resolved experiments. Results will be compared to typical findings from simple oxidic supports and metal single crystals. This review may be of interest for future photocatalyst development for applications such as solar fuel synthesis and related problems.

Al-Shamery, K.; Al-Shemmary, A.; Buchwald, R.; Hoogestraat, D.; Kampling, M.; Nickut, P.; Wille, A.

2010-05-01

136

Aggregate breakdown of nanoparticulate titania  

NASA Astrophysics Data System (ADS)

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.

Venugopal, Navin

137

Direct Selling  

Microsoft Academic Search

This paper provides a method of identifying international markets for which new products marketed via direct selling may be commercially successful. Results of the study indicate that consumer wealth, urbanization and literacy may be used as lead indicators of new product, direct selling success. It is recommended that multinational firms consider the use of a direct selling strategy when launching

Martin L. Schwartz

1993-01-01

138

Direct Variation  

NSDL National Science Digital Library

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.

2012-01-01

139

Comparison of High-Throughput Electrochemical Methods for Testing Direct Methanol Fuel Cell Anode Electrocatalysts  

Microsoft Academic Search

The screening and testing of fuel cell electrocatalysts often involves comparisons under conditions that do not closely match their use in membrane electrode assemblies. We compared the activities of several commercial and homemade Pt and PtRu catalysts for electrochemical methanol oxidation by four different techniques; disk electrode linear sweep voltammetry in aqueous methanol\\/ sulfuric acid solutions, optical fluorescence detection in

Benny C. Chan; Renxuan Liu; Krishnakumar Jambunathan; Hong Zhangc; Guoying Chen; Thomas E. Mallouk; Eugene S. Smotkinb

2005-01-01

140

Advance Directives  

Cancer.gov

A fact sheet about advance directives, which are legal documents that allow people to communicate their decisions about medical care to family, friends, and health care professionals in the event that they are unable to make those decisions themselves.

141

Nanostructured self-assembly materials from neat and aqueous solutions of C18 lipid pro-drug analogues of Capecitabine?a chemotherapy agent. Focus on nanoparticulate cubosomes? of the oleyl analogue  

SciTech Connect

A series of prodrug analogues based on the established chemotherapy agent, 5-fluorouracil, have been prepared and characterized. C18 alkyl and alkenyl chains with increasing degree of unsaturation were attached to the N{sup 4} position of the 5-fluorocytosine (5-FC) base via a carbamate bond. Physicochemical characterization of the prodrug analogues was carried out using a combination of differential scanning calorimetry, cross-polarized optical microscopy, X-ray diffraction and small-angle X-ray scattering. The presence of a monounsaturated oleyl chain was found to promote lyotropic liquid crystalline phase formation in excess water with a fluid lamellar phase observed at room temperature and one or more bicontinuous cubic phases at 37 C. The bulk phase was successfully dispersed into liposomes or cubosomes at room and physiological temperature respectively. In vitro toxicity of the nanoparticulate 5-FCOle dispersions was evaluated against several normal and cancer cell types over a 48 h period and exhibited an IC{sub 50} of 100 {micro}M against all cell types. The in vivo efficacy of 5-FCOle cubosomes was assessed against the highly aggressive mouse 4T1 breast cancer model and compared to Capecitabine (a water-soluble commercially available 5-FU prodrug) delivered at the same dosages. After 21 days of treatment, the 0.5 mmol 5-FCOle treatment group exhibited a significantly smaller average tumour volume than all other treatment groups including Capecitabine at similar dosage. These results exemplify the potential of self-assembled amphiphile prodrugs for delivery of bioactives in vivo.

Gong, Xiaojuan; Moghaddam, Minoo J.; Sagnella, Sharon M.; Conn, Charlotte E.; Mulet, Xavier; Danon, Stephen J.; Waddington, Lynne J.; Drummond, Calum J.

2012-02-06

142

Direct visualization of gastrointestinal tract with lanthanide-doped BaYbF5 upconversion nanoprobes.  

PubMed

Nanoparticulate contrast agents have attracted a great deal of attention along with the rapid development of modern medicine. Here, a binary contrast agent based on PAA modified BaYbF5:Tm nanoparticles for direct visualization of gastrointestinal (GI) tract has been designed and developed via a one-pot solvothermal route. By taking advantages of excellent colloidal stability, low cytotoxicity, and neglectable hemolysis of these well-designed nanoparticles, their feasibility as a multi-modal contrast agent for GI tract was intensively investigated. Significant enhancement of contrast efficacy relative to clinical barium meal and iodine-based contrast agent was evaluated via X-ray imaging and CT imaging in vivo. By doping Tm(3+) ions into these nanoprobes, in vivo NIR-NIR imaging was then demonstrated. Unlike some invasive imaging modalities, non-invasive imaging strategy including X-ray imaging, CT imaging, and UCL imaging for GI tract could extremely reduce the painlessness to patients, effectively facilitate imaging procedure, as well as rationality economize diagnostic time. Critical to clinical applications, long-term toxicity of our contrast agent was additionally investigated in detail, indicating their overall safety. Based on our results, PAA-BaYbF5:Tm nanoparticles were the excellent multi-modal contrast agent to integrate X-ray imaging, CT imaging, and UCL imaging for direct visualization of GI tract with low systemic toxicity. PMID:23849344

Liu, Zhen; Ju, Enguo; Liu, Jianhua; Du, Yingda; Li, Zhengqiang; Yuan, Qinghai; Ren, Jinsong; Qu, Xiaogang

2013-07-09

143

Future direction of direct writing  

Microsoft Academic Search

Direct write technology using special inks consisting of finely dispersed metal nanoparticles in liquid is receiving an undivided attention in recent years for its wide range of applicability in modern electronic industry. The application of this technology covers radio frequency identification-tag (RFID-tag), flexible-electronics, organic light emitting diodes (OLED) display, e-paper, antenna, bumpers used in flip-chip, underfilling, frit, miniresistance applications and

Nam-Soo Kim; Kenneth N. Han

2010-01-01

144

Direct cervicoplasty.  

PubMed

The sagging neck, or "turkey gobbler" deformity, is one of the more common reasons that patients present to facial plastic surgeons. Although many of these patients might be best improved by a full rhytidectomy with periauricular incisions, skin flap undermining, and platysmal tightening, there are some patients who do not wish to undergo a full rhytidectomy. Some of these patients may be reasonably well served by a direct cervicoplasty or submentoplasty. The advantages of this approach include shorter operative time, faster recovery, and lower complication rates. The primary disadvantage is an anterior cervical incision that may be visible under some conditions. This article will review the options for skin incisions as well as technical details that may lead to a successful rejuvenation of the submental region. PMID:22418816

Jordan, J Randall

2012-03-14

145

Freeze Drying: Potential for Powdered Nanoparticulate Product  

Microsoft Academic Search

Nanoparticles were prepared by using an emulsion solvent evaporation method. Further, the drying of an anti-cancer drug of proprietary nature (nanosized) was carried out by a freeze-drying technique to get a free-flowing powder. A systematic approach was developed to study the freeze-drying technique for polymeric nanoparticles. Initially, the freeze-thawing experiments were carried out with varying concentrations of cryoprotectants to screen

V. V. Patil; P. P. Dandekar; V. B. Patravale; B. N. Thorat

2010-01-01

146

Radio Direction Finding.  

National Technical Information Service (NTIS)

Discussed in the book are the theoretical principles of radio direction finding and the operating principles of the various types of radio direction finders. Questions concerned with the practical use of ground station radio direction finders are reviewed...

E. S. Goikhman M. I. Rogatkin V. A. Vartanesyan

1970-01-01

147

Direct Selling in Malaysia  

Microsoft Academic Search

Direct selling is growing dramatically in Malaysia. This paper discusses continuing trends that promote the expansion of direct selling. It then suggests a categorization of the sales force, the marketing mix utilized, and the regulatory environment for direct selling. This paper proposes that positive development of the direct selling sector is based on four factors: regulating entry, educating industry participants

Osman Zain; Zahir A. Quraeshi; Mohd. Ashaari Idris

2000-01-01

148

Influences of both carbon supports and heat-treatment of supported catalyst on electrochemical oxidation of methanol  

Microsoft Academic Search

The effects of carbon supports for platinum-ruthenium (Pt-Ru) catalysts on anode performance of direct methanol fuel cells (DMFC) were investigated. Good polarization characteristics of the methanol electrode were obtained for a Pt-Ru catalyst supported on an acetylene black with high specific surface area and a pore size distribution in the range of 3 to 8 nm. The performance of the

Makoto Uchida; Yuko Aoyama; Mieko Tanabe; Nobuyuki Yanagihara; Nobuo Eda; Akira Ohta

1995-01-01

149

Direct Selling Channels  

Microsoft Academic Search

Direct selling channels are changing. Throughout the world, customers, sales representatives, direct selling companies, and the societies in which they exist are changing rapidly. This paper examines chages in each of the above-mentioned major \\

Ben M. Enis

1993-01-01

150

Twisting Direction in Sports.  

ERIC Educational Resources Information Center

|The results of two research projects concerned with eye dominance, cortical dominance, handedness, and twisting direction are reviewed and indicate that twisting direction is not related to the other variables but is taught. (JMF)|

Wilkerson, James E.; Brown, James

1979-01-01

151

Directional recoil rates for WIMP direct detection  

SciTech Connect

New techniques for the laboratory direct detection of dark matter weakly interacting massive particles (WIMPs) are sensitive to the recoil direction of the struck nuclei. We compute and compare the directional recoil rates dR/dcos{theta} (where {theta} is the angle measured from a reference direction in the sky) for several WIMP velocity distributions including the standard dark halo and anisotropic models such as Sikivie's late-infall halo model and logarithmic-ellipsoidal models. Since some detectors may be unable to distinguish the beginning of the recoil track from its end (lack of head-tail discrimination), we introduce a folded directional recoil rate dR/d|cos{theta}|, where |cos{theta}| does not distinguish the head from the tail of the track. We compute the CS{sub 2} and CF{sub 4} exposures required to distinguish a signal from an isotropic background noise, and find that dR/d|cos{theta}| is effective for the standard dark halo and some but not all anisotropic models.

Alenazi, Moqbil S.; Gondolo, Paolo [Department of Physics, University of Utah, 115 S 1400 E Rm 201, Salt Lake City, Utah 84112-0830 (United States)

2008-02-15

152

Direct energy conversion systems  

Microsoft Academic Search

The potential importance of direct energy conversion to the long-term development of fusion power is discussed with stress on the possibility of alleviating waste heat problems. Two approaches to direct conversion, i.e., direct collection and magnetic expansion are reviewed. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Keywords (in text

G. H. Miley

1978-01-01

153

Psychometrics of Direct Observation  

Microsoft Academic Search

Abstract.Direct observation plays an important role in the assessment practices of school psychologists and in the development,of evidence-based practices in general and special education. The defining psychometric,features of direct ob- servation are presented, the contributions to assessment practice reviewed, and a specific proposal is offered for evaluating the psychometric merit of direct obser- vation in both practitioner developed and commercial\\/research

John M. Hintze

154

Suicide by advance directive?  

Microsoft Academic Search

The medical response to suicide is generally resuscitation, followed by attempts to maximise the patient's recovery. Care is generally withdrawn when it is futile and there is no hope for recovery. Suicidal patients who have completed an advance directive may complicate matters. Should medical providers not resuscitate a patient with an advance directive who has attempted to commit suicide? If

D Sontheimer

2008-01-01

155

Decisions Concerning Directional Dependence  

ERIC Educational Resources Information Center

In this rejoinder, von Eye and DeShon discuss the decision strategies proposed in their original article ("Directional Dependence in Developmental Research," this issue), as well as the ones proposed by the authors of the commentary (Pornprasertmanit and Little, "Determining Directional Dependency in Causal Associations," this issue). In addition,

von Eye, Alexander; DeShon, Richard P.

2012-01-01

156

Numerical Directional Overcurrent Protection  

Microsoft Academic Search

The paper reports the development of algorithms and digital signal processing technique for directional overcurrent protection applicable to both phase faults and earth faults. The algorithm for overcurrent protection is complemented with a new digital signal processing which provides a reliable scheme for fault direction determination. The scheme is based on the use of symmetrical-phase-sequence components of voltages and currents

T. T. Nguyen

157

Direct Conversion of Energy.  

ERIC Educational Resources Information Center

|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

Corliss, William R.

158

Direct phase retrieval  

Microsoft Academic Search

A direct, noniterative approach to retrieving a multidimensional complex image (i.e., its phase can vary from pixel to pixel) from the magnitude of its Fourier transform is developed. The uniqueness of the reconstruction is shown to be a direct consequence of the existence of zero surfaces or sheets in the multidimensional z transforms of the image. The analytic properties of

W. Fright; R. Bates

1987-01-01

159

Determinants of Direct Democracy  

Microsoft Academic Search

This paper investigates on the demographic, economic, political and cultural determinants of direct democracy in 87 countries using an index of direct democracy. The test is interesting since there are important variations across these countries in the referendum and initiative use. We apply a number of estimation techniques. We find that per capita income, education and a larger share of

Nadia Fiorino; Roberto Ricciuti

2007-01-01

160

Self-Directed Learning  

NSDL National Science Digital Library

This site supports teaching self-directed learning (SDL) and becoming a self-directed person. It supports home-schooling, experiential education, open schooling and life-long learning. Keeping a journal, setting goals, planning and taking action are key tools. Self-improvement, personal development and the development of character are central themes of SDL.

Maurice Gibbons (Personal Power Press)

2008-01-01

161

Direct marketing attitudes  

Microsoft Academic Search

The study examines empirically consumers' attitudes toward direct marketing using a sample of 354 consumers. The sample was randomly drawn from a large southern metropolitan area. The study instrument comprised items developed from literature sources. Respondents' evaluations of the items were obtained through in-home personal interviews. Underlying the study is the hypothesis that consumers' attitudes toward direct marketing are a

Daulatram Lund; Pradeep K. Korgaonkar

1995-01-01

162

Directionality of dog vocalizations  

NASA Astrophysics Data System (ADS)

The directionality patterns of sound emission in domestic dogs were measured in an anechoic environment using a microphone array. Mainly long-distance signals from four dogs were investigated. The radiation pattern of the signals differed clearly from an omnidirectional one with average differences in sound-pressure level between the frontal and rear position of 3-7 dB depending from the individual. Frequency dependence of directionality was shown for the range from 250 to 3200 Hz. The results indicate that when studying acoustic communication in mammals, more attention should be paid to the directionality pattern of sound emission.

Frommolt, Karl-Heinz; Gebler, Alban

2004-07-01

163

Consumer Directed Broadcast Advertisements  

Center for Biologics Evaluation and Research (CBER)

Text Version... human and animal drugs, including biological products for humans, directly to consumers through broadcast media, such as television, radio, or ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

164

Direct SAW Frequency Synthesizer.  

National Technical Information Service (NTIS)

A frequency synthesizer utilizing three elementary direct synthesizers to achieve fast frequency hopping among 219 tones is described. The elementary synthesizers used for the two 9-channel sets of tones consist of a comb generator followed by a surface a...

A. J. Budreau P. H. Carr

1978-01-01

165

AISI direct steelmaking program  

SciTech Connect

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.

Aukrust, E.

1991-01-09

166

Direct nuclear pumped laser  

DOEpatents

There is provided a direct nuclear pumped gas laser in which the lasing mechanism is collisional radiated recombination of ions. The gas laser active medium is a mixture of the gases, with one example being neon and nitrogen.

Miley, George H. (Champagne, IL); Wells, William E. (Urbana, IL); DeYoung, Russell J. (Hampton, VA)

1978-01-01

167

The Directed Case Method  

NSDL National Science Digital Library

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

Curtin, Leslie N.; Cliff, William H.

2000-09-01

168

Direct conversion technology  

Microsoft Academic Search

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

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

1988-01-01

169

Direct conversion technology  

Microsoft Academic Search

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,

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

1989-01-01

170

Refrigerant directly cooled capacitors  

DOEpatents

The invention is a direct contact refrigerant cooling system using a refrigerant floating loop having a refrigerant and refrigeration devices. The cooling system has at least one hermetic container disposed in the refrigerant floating loop. The hermetic container has at least one electronic component selected from the group consisting of capacitors, power electronic switches and gating signal module. The refrigerant is in direct contact with the electronic component.

Hsu, John S. (Oak Ridge, TN); Seiber, Larry E. (Oak Ridge, TN); Marlino, Laura D. (Oak Ridge, TN); Ayers, Curtis W. (Kingston, TN)

2007-09-11

171

Authenticated Directed Diffusion  

Microsoft Academic Search

Directed Diffusion(DD) is a method of data dissemination especially suitable in distributed sensing scenarios. It has been\\u000a known well in the application of wireless sensor network routing. Although it is very popular as a data-centric routing protocol\\u000a for wireless sensor network(WSN), it faces several types of serious attacks. We proposes a new protocol (Authenticated Directed\\u000a Diffusion (ADD)) which extends the

Eric K. Wang; Lucas Chi Kwong Hui; Siu-ming Yiu

2008-01-01

172

Direct energy conversion  

Microsoft Academic Search

A comprehensive review of methods for direct energy conversion and energy storage is presented.Included are selected applications and brief reviews of underlying principles of each method. Principal chapter coverage is devoted to thermoelectric, photovoltaic, thermionic and magnetohydrodynamic generators. Other modes of energy conversion briefly covered are as follows: Nernst effect, ferroelectric, thermomagnetic, thermo-photo-voltaic, electrohydrodynamic, electrokinetic, piezoelectric, radiation, direct charging devices,

Angrist

1976-01-01

173

Directed network modules  

NASA Astrophysics Data System (ADS)

A search technique locating network modules, i.e. internally densely connected groups of nodes in directed networks is introduced by extending the clique percolation method originally proposed for undirected networks. After giving a suitable definition for directed modules we investigate their percolation transition in the Erdos Rnyi graph both analytically and numerically. We also analyse four real-world directed networks, including Google's own web-pages, an email network, a word association graph and the transcriptional regulatory network of the yeast Saccharomyces cerevisiae. The obtained directed modules are validated by additional information available for the nodes. We find that directed modules of real-world graphs inherently overlap and the investigated networks can be classified into two major groups in terms of the overlaps between the modules. Accordingly, in the word-association network and Google's web-pages, overlaps are likely to contain in-hubs, whereas the modules in the email and transcriptional regulatory network tend to overlap via out-hubs.

Palla, Gergely; Farkas, Ills J.; Pollner, Pter; Dernyi, Imre; Vicsek, Tams

2007-06-01

174

Direct Photons at RHIC  

SciTech Connect

Direct photons are ideal tools to investigate kinematical and thermodynamical conditions of heavy ion collisions since they are emitted from all stages of the collision and once produced they leave the interaction region without further modification by the medium. The PHENIX experiment at RHIC has measured direct photon production in p+p and Au+Au collisions at 200 GeV over a wide transverse momentum (p{sub T}) range. The p+p measurements allow a fundamental test of QCD, and serve as a baseline when we try to disentangle more complex mechanisms producing high p{sub T} direct photons in Au+Au. As for thermal photons in Au+Au we overcome the difficulties due to the large background from hadronic decays by measuring 'almost real' virtual photons which appear as low invariant mass e{sup +}e{sup -} pairs: a significant excess of direct photons is measured above the above next-to-leading order perturbative quantum chromodynamics calculations. Additional insights on the origin of direct photons can be gained with the study of the azimuthal anisotropy which benefits from the increased statistics and reaction plane resolution achieved in RHIC Year-7 data.

Gabor,D.

2008-07-29

175

Direct conversion technology  

NASA Astrophysics Data System (ADS)

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.

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

1989-12-01

176

Direct conversion technology  

SciTech Connect

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.

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

1992-01-07

177

A love-wave sensor for direct detection of biofunctionalized nanoparticles  

Microsoft Academic Search

In this work, we have designed and manufactured Love wave sensors equipped with a liquid cell for the detection of bio-functionalized nano-particules in water. Measurements using these devices are based on the determination of velocity and propagation loss changes of a guided acoustic shear wave generated by Inter-Digital Transducers (IDTs) patterned on a (YXlt)\\/36deg\\/90deg cut of quartz and passivated by

L. El Fissi; J.-M. Friedt; V. Luzet; F. Cherioux; G. Martin; S. Ballandras

2009-01-01

178

Direct Conversion Technology  

SciTech Connect

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)

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

1992-07-01

179

Fermilab Library directions  

SciTech Connect

In this document, we indicate our current thinking about the directions of the Fermilab Library. The ideas relate to the preprint management issue in a number of ways. The ideas are subject to revision as we come to understand what is possible as well as what is needed by the Laboratory community. This document should therefore be regarded as our personal view--the availability of off-the-shelf technology, of funding as well as feedback from the laboratory community about their needs will all affect how far we actually proceed in any of these directions.

Garrett, P.; Ritchie, D.

1990-05-04

180

Direct Conversion Technology  

NASA Astrophysics Data System (ADS)

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.

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

1992-07-01

181

Seeing and Hearing Directly  

Microsoft Academic Search

According to Paul Snowdon, one directly perceives an object x iff one is in a position to make a true demonstrative judgement of the form That is x. Whenever one perceives\\u000a an object x indirectly (or dependently, as Snowdon puts it) it is the case that there exists an item y (which is not identical to x) such that one

Hannes Ole Matthiessen

2010-01-01

182

Future technical directions  

Microsoft Academic Search

The areas of more recent technical advances are discussed. These are necessarily limited to those areas approved for public dissemination. The presentation is organized as follows: new directions in the Space Shuttle Main Engine (SSME); Computational Fluid Dynamics (CFD) advances; and other areas of technology advances. The advances in the SSME are focused on the continued support to reliable flights

Eugene D. Jackson; Munir Sindir

1993-01-01

183

Direct Drive Wind Turbine.  

National Technical Information Service (NTIS)

A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned rad...

C. Bevington D. Costin G. Bywaters J. Stowell W. Banforth

2004-01-01

184

Is there directional smelling?  

Microsoft Academic Search

Summary The aim of the present study was to establish the crucial precondition for directional smelling, i.e. the ability of humans to discriminate between odorous stimuli perceived either from the right or from the left side. When the pure odorants hydrogen sulphide or vanillin were used as stimulants localization was random. On the other hand stimulation with carbon dioxide or

G. Kobal; S. Van Toller; T. Hummel

1989-01-01

185

The Directed Case Method.  

ERIC Educational Resources Information Center

|Provides an example of a directed case on human anatomy and physiology. Uses brief real life newspaper articles and clinical descriptions of medical reference texts to describe an actual, fictitious, or composite event. Includes interrelated human anatomy and physiology topics in the scenario. (YDS)|

Cliff, William H.; Curtin, Leslie Nesbitt

2000-01-01

186

DIRECTED HYPERGRAPHS AND APPLICATIONS(*)  

Microsoft Academic Search

We deal with directed hypergraphs as a tool to model and solve some classes of problems arising in Operations Research and in Computer Science. Concepts such as connectivity, paths and cuts are defined. An extension of the main duality results to a special class of hypergraphs is presented. Algorithms to perform visits of hypergraphs and to find optimal paths are

Giorgio Gallo; Giustino Longo; Sang Nguyen; Stefano Pallottino

1992-01-01

187

Knowledge-directed learning  

Microsoft Academic Search

A system embodying a knowledge-directed approach to unsupervised learning is examined in this paper. This approach is based on the premise that knowledge of new situations is acquired and interpreted in terms of the previous knowledge brought to the learning situation. In particular, our system is provided with a general characterization of action-oriented competitive games. This frame of reference is

Elliot M. Soloway; Edward M. Riseman

1977-01-01

188

Audio direct broadcast satellites  

NASA Astrophysics Data System (ADS)

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.

Miller, J. E.

1983-05-01

189

Coatings for Directional Eutectics.  

National Technical Information Service (NTIS)

Significant advances have been made in the development of an environmentally stable coating for a very high strength, directionally solidified eutectic alloy designated NiTaC-13. Three duplex (two-layer) coatings survived 3,000 hours on a cyclic oxidation...

J. R. Rairden M. R. Jackson

1976-01-01

190

Developing Ethical Direction  

ERIC Educational Resources Information Center

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

Ribble, Mike S.; Bailey,Gerald D.

2005-01-01

191

Direct Multizone System.  

ERIC Educational Resources Information Center

Describes Lennox indoor direct multizone equipment and controls. The following areas are covered--(1) unit features, (2) controls and operations, (3) approvals, (4) air patterns, (5) typical applications, (6) specifications and ratings, (7) dimensioned drawings of a typical unit, (8) mixing boxes, (9) blower data, (10) water valve selection and

Lennox Industries, Inc., Marshalltown, IA.

192

Conclusions and Future Directions  

ERIC Educational Resources Information Center

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

Lillibridge, Fred

2012-01-01

193

NCI at Frederick: Directions  

Cancer.gov

Enter your address in the field provided below to get door to door directions to the Frederick campus. Please be aware that you will be asked to provide Ft. Detrick security with proof of identification, and your vehicle will be briefly searched, before being allowed to enter the facility grounds.

194

Core Directions in HRD.  

ERIC Educational Resources Information Center

|This document consists of four papers presented at a symposium on core directions in human resource development (HRD) moderated by Verna Willis at the 1996 conference of the Academy of Human Resource Development. "Reengineering the Organizational HRD Function: Two Case Studies" (Neal Chalofsky) reports an action research study in which the

1996

195

Dragonfly directional sensor  

NASA Astrophysics Data System (ADS)

This paper discusses the concept and hardware development of an all fiber-based, solid state, coherent array directional sensor that can locate and track bright objects against a darker background. This sensor is not an imager. It relies on the inherent structure of the global fiber distribution. Methods for characterizing and calibrating hardware embodiments are also presented.

Geary, Joe; Blackwell, Lisa; Edwards, Tim; Dargie, Mike

2013-02-01

196

Direct syntheses of La{sub n+1}Ni{sub n}O{sub 3n+1} phases (n=1, 2, 3 and {infinity}) from nanosized co-crystallites  

SciTech Connect

A new direct route for the 'bottom up' syntheses of phases in the La{sub n+1}Ni{sub n}O{sub 3n+1} series (n=1, 2, 3 and {infinity}) has been achieved via single-step heat treatments of nanosized co-crystallized precursors. The co-crystallized precursors were prepared using a continuous hydrothermal flow synthesis system that uses a superheated water flow at ca. 400 deg. C and 24.1 MPa to produce nanoparticulate slurries. Overall, a significant reduction in time and number of steps for the syntheses of La{sub 3}Ni{sub 2}O{sub 7} and La{sub 4}Ni{sub 3}O{sub 10} was achieved compared with more conventional synthesis methods, which typically require multiple homogenization and reheating steps over several days. - Graphical abstract: Scanning electron micrograph of La{sub 4}Ni{sub 3}O{sub 10} (bar=1 {mu}m) made by a single heat treatment at 1075 deg. C in air for 12 h of a 4:3 La:Ni ratio co-crystallite mixture of the metal hydroxides.

Weng Xiaole; Boldrin, Paul [Department of Chemistry, Christopher Ingold Laboratories, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); School of Engineering and Material Sciences, Queen Mary University of London, London E1 4NS (United Kingdom); Abrahams, Isaac [Centre for Materials Research, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Skinner, Stephen J. [Department of Materials, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Kellici, Suela [Department of Chemistry, Christopher Ingold Laboratories, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Darr, Jawwad A. [Department of Chemistry, Christopher Ingold Laboratories, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)], E-mail: j.a.darr@ucl.ac.uk

2008-05-15

197

Portable direct reading instruments  

NASA Astrophysics Data System (ADS)

Direct reading instruments are those instruments in which the analysis of the contaminant is carried out within the instrument itself. When selecting equipment, the industrial hygienist must consider the physical characteristics of the instruments as well as their performance characteristics and price. Some of the methods of detection that are used in instruments with multi-gas detection capabilities are: photoionization, Flame ionization, infrared, gas chromatography, infrared photoacoustic, and electrochemical.

Hermon-Cruz, Ivette Z.

1991-09-01

198

Direct and Inverse Variation  

NSDL National Science Digital Library

Lesson 1 of two lessons teaches students about direct variation by allowing them to explore a simulated oil spill using toilet paper tissues (to represent land) and drops of vegetable oil (to simulate a volume of oil). Lesson 2 teaches students about inverse variation by exploring the relationship between the heights of a fixed amount of water poured into cylindrical containers of different sizes as compared to the area of the containers' bases.

Media, Annenberg

2009-12-23

199

Direct detection of WIMPs  

NASA Astrophysics Data System (ADS)

To test the hypothesis according to which Weakly Interacting Massive Particles are a major constituent of Dark Matter, direct detection experiments aim at detecting the spectrum of nuclear recoils induced by WIMPs from the Milky Way halo within a target material. While the detection concept is already more than 20 years old, recent experimental developments have allowed fast progress, which up to now have lead to constrain electroweak theories beyond the standard model in a complementary way to collider experiments.

Armengaud, Eric

2012-07-01

200

Direct subnanosecond voltage monitors  

SciTech Connect

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.

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

1981-01-01

201

Future directions for QCD  

SciTech Connect

New directions for exploring QCD at future high-energy colliders are sketched. These include jets within jets. BFKL dynamics, soft and hard diffraction, searches for disoriented chiral condensate, and doing a better job on minimum bias physics. The new experimental opportunities include electron-ion collisions at HERA, a new collider detector at the C0 region of the TeVatron, and the FELIX initiative at the LHC.

Bjorken, J.D.

1996-10-01

202

Direct conversion technology  

NASA Astrophysics Data System (ADS)

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.

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

1988-12-01

203

Direct observation detonator operation  

NASA Astrophysics Data System (ADS)

The analysis of detonator-timing performance has involved the use of rotating-mirror cameras (RMC) used in the streak mode and high-speed film. Fiducial timing marks are applied to the film to provide temporal references. The use of a RMC for detonator analysis requires aligning the camera, performing an exposure test, capturing light from the detonation and then processing the film. This procedure can take up to an hour for two technicians. After the film is possessed another technician compares each light streak on the film with the fiducial timing marks also recorded on the film. Capturing light from a detonator and recording it directly to a digitizer can improve detonator-timing measurement in several ways. The digitized signals can then be directly analyzed with software. The direct recording method reduces the need for expensive rotating mirror cameras, film processing and subjective optical measurement comparison. Furthermore, an extensive support facility requiring several specialized technicians is reduced to a single technician in a modest laboratory. This technician is then capable of performing several tests an hour. Tests were preformed to measure light intensity at detonation. An optical method of capturing the light was designed using a remote microscope coupled to optical fiber to bring the light to an optical/electrical converter and a digitizer then records the signal. This system is presently used in parallel with a RMC. The results are compared for accuracy.

Hall, Charles R.

2001-11-01

204

Direct reciprocity on graphs  

PubMed Central

Direct reciprocity is a mechanism for the evolution of cooperation based on the idea of repeated encounters between the same two individuals. Here we examine direct reciprocity in structured populations, where individuals occupy the vertices of a graph. The edges denote who interacts with whom. The graph represents spatial structure or a social network. For birth-death or pairwise comparison updating, we find that evolutionary stability of direct reciprocity is more restrictive on a graph than in a well-mixed population, but the condition for reciprocators to be advantageous is less restrictive on a graph. For death-birth and imitation updating, in contrast, both conditions are easier to fulfill on a graph. Moreover, for all four update mechanisms, reciprocators can dominate defectors on a graph, which is never possible in a well-mixed population. We also study the effect of an error rate, which increases with the number of links per individual; interacting with more people simultaneously enhances the probability of making mistakes. We provide analytic derivations for all results.

Ohtsuki, Hisashi; Nowak, Martin A.

2008-01-01

205

Human perioral directional sensitivity.  

PubMed

The capacity of 41 neurologically healthy young adults to distinguish opposing directions of brush motion across the skin innervated by the mental nerve was determined. The velocity and orientation and the length and width of skin traversed by the moving tactile stimuli were carefully controlled. Directional sensitivity, d', was found to vary curvilinearly with velocity over the range 0.5 to 32 cm/s. Because the data from most subjects were well described by a generalized gamma function, it was possible to characterize this velocity dependency quantitatively. Specifically, indices derived from these functions were found to describe the subject's peak (i.e., maximal) sensitivity, the velocity which resulted in peak sensitivity (i.e., the optimal velocity), and the degree to which stimulus velocity influenced the ability to recognize direction of motion (i.e., the velocity-tuning of d'). Peak sensitivity, optimal velocity, and the degree of global velocity-tuning were found to differ between males and females. Confidence limits (the lower and upper 2.5% points) for the normative data were determined to enable detection and characterization of deficits in orofacial tactile motion sensitivity in individuals with damaged mandibular nerves. PMID:3366203

Essick, G K; Afferica, T; Aldershof, B; Nestor, J; Kelly, D; Whitsel, B

1988-06-01

206

Short Mode Selective Directional Couplers.  

National Technical Information Service (NTIS)

Short mode selective directional couplers for transverse electric (TE) modes travelling in overmoded circular waveguides are described. Directivity is achieved by pairs of holes with destructive interference in backward direction, unwanted modes are suppr...

G. Janzen H. Stickel

1983-01-01

207

Directed energy planetary defense  

NASA Astrophysics Data System (ADS)

Asteroids and comets that cross Earth's orbit pose a credible risk of impact, with potentially severe disturbances to Earth and society. Numerous risk mitigation strategies have been described, most involving dedicated missions to a threatening object. We propose an orbital planetary defense system capable of heating the surface of potentially hazardous objects to the vaporization point as a feasible approach to impact risk mitigation. We call the system DE-STAR for Directed Energy System for Targeting of Asteroids and exploRation. DE-STAR is a modular phased array of kilowatt class lasers powered by photovoltaic's. Modular design allows for incremental development, test, and initial deployment, lowering cost, minimizing risk, and allowing for technological co-development, leading eventually to an orbiting structure that would be developed in stages with both technological and target milestones. The main objective of DE-STAR is to use the focused directed energy to raise the surface spot temperature to ~3,000K, allowing direct vaporization of all known substances. In the process of heating the surface ejecting evaporated material a large reaction force would alter the asteroid's orbit. The baseline system is a DE-STAR 3 or 4 (1-10km array) depending on the degree of protection desired. A DE-STAR 4 allows for asteroid engagement starting beyond 1AU with a spot temperature sufficient to completely evaporate up to 500-m diameter asteroids in one year. Small asteroids and comets can be diverted/evaporated with a DESTAR 2 (100m) while space debris is vaporized with a DE-STAR 1 (10m).

Lubin, Philip; Hughes, Gary B.; Bible, Johanna; Bublitz, Jesse; Arriola, Josh; Motta, Caio; Suen, Jon; Johansson, Isabella; Riley, Jordan; Sarvian, Nilou; Clayton-Warwick, Deborah; Wu, Jane; Milich, Andrew; Oleson, Mitch; Pryor, Mark; Krogen, Peter; Kangas, Miikka

2013-09-01

208

Antiemetic research: future directions  

Microsoft Academic Search

Purpose and methodsAs a part of reviewing the Multinational Association of Supportive Care in Cancer (MASCC) antiemetic guidelines in Perugia\\u000a in 2009, an expert group identified directions for future antiemetic research.\\u000a \\u000a \\u000a \\u000a \\u000a Results and conclusionsIn future trials, the prediction of nausea and vomiting may combine algorithms based on observed prognostic factors relating\\u000a to the patient and the anticancer therapy, the identification

Ian Olver; Alexander Molassiotis; Matti Aapro; Jrn Herrstedt; Steven Grunberg; Garry Morrow

2011-01-01

209

The Direction of Gravity  

NASA Astrophysics Data System (ADS)

Given a uniformly dense sphere with a hole through its center, gravity is supposed to cause an object dropped into the hole to oscillate between the extremities. This is a prediction of both Newton's and Einstein's theories of gravity. Though every physicist knows what is supposed to happen, nobody has ever seen it happen. Failure to back up the predicted oscillation with empirical evidence is not due to insurmountable technical obstacles; a laboratory experiment to test it is quite feasible. According to the ideals of science, we should not be satis ed with analogies or extrapolations suggesting that the prediction is correct. We should, if possible, get the answer directly from Nature.

Benish, R.

2011-06-01

210

Probiotics: future directions.  

PubMed

Clinical studies have shown that certain probiotics may be useful in treating a variety of diarrheal disorders, including rotavirus diarrhea, antibiotic-associated diarrhea, Clostridium difficile diarrhea, and traveler's diarrhea. New data suggest that probiotics might be useful in controlling inflammatory diseases, treating and preventing allergic diseases, preventing cancer, and stimulating the immune system, which may reduce the incidence of respiratory disease. Different modes of administering probiotics are currently being investigated, which may ultimately lead to the widespread use of probiotics in functional foods. It is important that such practices be directed by carefully controlled clinical studies published in peer-reviewed journals. PMID:11393194

Vanderhoof, J A

2001-06-01

211

Omni-directional railguns  

DOEpatents

A device for electromagnetically accelerating projectiles. The invention features two parallel conducting circular plates, a plurality of electrode connections to both upper and lower plates, a support base, and a projectile magazine. A projectile is spring-loaded into a firing position concentrically located between the parallel plates. A voltage source is applied to the plates to cause current to flow in directions defined by selectable, discrete electrode connections on both upper and lower plates. Repulsive Lorentz forces are generated to eject the projectile in a 360 degree range of fire.

Shahinpoor, Mohsen (9521 Avenida Del Oso NE., Albuquerque, NM 87111)

1995-01-01

212

Direct broadcast satellite receivers  

NASA Astrophysics Data System (ADS)

The feasibility of broadcasting direct to the home from a geostationary satellite was recognized at least two decades ago and by the mid-1960s the receiver industry was already considering the implications. Attention is given to allocations and transmission parameters, broadcast satellite plans, television receiving systems, individual satellite television receiver components, and aspects of sound broadcast reception. It is concluded that satellite television broadcasting services will be introduced by a number of European countries in the next two or three years. The requirement for mass-produced equipment for individual reception of such signals has been shown to be realizable, and development of low-cost solutions is now in progress.

Freeman, K. G.

1982-03-01

213

Omni-directional railguns  

DOEpatents

This invention is comprised of a device for electromagetically accelerating projectiles. The invention features two parallel conducting circular plates, a plurality of electrode connections to both upper and lower plates, a support base, and a projectile magazine. A projectile is spring-loaded into a firing position concentrically located between the parallel plates. A voltage source is applied to the plates to cause current to flow in directions defined by selectable, discrete electrode connections on both upper and lower plates. Repulsive Lorentz forces are generated to eject the projectile in a 360 degree range of fire.

Shahinpoor, M.

1994-12-31

214

Direct Production of Copper  

NASA Astrophysics Data System (ADS)

The use of commercially pure oxygen in flash smelting a typical chalcopyrite concentrate or a low grade comminuted matte directly to copper produces a large excess of heat. The heat balance is controlled by adjusting the calorific value of the solid feed. A portion of the sulfide material is roasted to produce a calcine which is blended with unroasted material, and the blend is then autogeneously smelted with oxygen and flux directly to copper. Either iron silicate or iron calcareous slags are produced, both being subject to a slag cleaning treatment. Practically all of the sulfur is contained in a continuous stream of SO2 gas, most of which is strong enough for liquefaction. A particularly attractive feature of these technologies is that no radically new metallurgical equipment needs to be developed. The oxygen smelting can be carried out not only in the Inco type flash furnace but in other suitable smelters such as cyclone furnaces. Another major advantage stems from abolishion of the ever-troublesome converter aisle, which is replaced with continuous roasting of a fraction of the copper sulfide feed.

Victorovich, G. S.; Bell, M. C.; Diaz, C. M.; Bell, J. A. E.

1987-09-01

215

Piezoelectric direct drive servovalve  

NASA Astrophysics Data System (ADS)

A single-stage servovalve using direct piezoelectric actuator drive is described. The single-stage servovalve design offers higher bandwidth than conventional two-stage valves. It takes advantage of the high energy density in piezoelectric materials while addressing the need for internal amplification of stroke. When used alone, the valve can regulate pressure, and when used in combination with a hydraulic output device it forms part of an effective servohydraulic actuator. Development of a direct drive prototype valve is described. Discussion includes design issues related to low stroke smart material actuators such as piezoelectrics. Component and subsystem testing and results are reviewed. Electronic drive and control of the piezoelectric and overall device along with performance in the control of fluid flow is discussed. The value of the new servovalve is shown in the combination of the valve with a hydraulic output device. Data are supplied for this servohydraulic actuator. The new actuator shows promise for a motion simulator application and more generally for motion control at higher bandwidth than is possible with currently available servohydraulics.

Lindler, Jason E.; Anderson, Eric H.

2002-07-01

216

Direct contact dissolution therapy.  

PubMed

Direct contact dissolution using MTBE is a safe, effective treatment for many patients with cholesterol gallstones when performed by clinicians experienced with this technique. This may be the treatment of choice for many patients at high risk for general anaesthesia or surgery. Cholecystostomy using local anaesthesia with subsequent stone extraction is an alternative requiring prolonged catheter drainage, and is associated with some risk and discomfort (Hawkyard et al, 1990). Most experts concur that laparoscopic cholecystectomy cannot be performed safely and comfortably without general anaesthesia under most circumstances. A second small population of patients are inordinately apprehensive about general anaesthesia or surgical removal of their gallbladder and refuse standard therapy in spite of recurrent biliary symptoms. Although direct contact dissolution is generally well tolerated, it may require several days of paramedical attention with medical supervision. This procedure will be most efficiently, effectively and comfortably performed by an experienced team and is, therefore, probably best provided by referral centres with physicians sufficiently interested in the treatment of biliary tract stone disease to develop expertise with this method. PMID:1486211

Thistle, J L

1992-11-01

217

Remote direct memory access  

SciTech Connect

Methods, parallel computers, and computer program products are disclosed for remote direct memory access. Embodiments include transmitting, from an origin DMA engine on an origin compute node to a plurality target DMA engines on target compute nodes, a request to send message, the request to send message specifying a data to be transferred from the origin DMA engine to data storage on each target compute node; receiving, by each target DMA engine on each target compute node, the request to send message; preparing, by each target DMA engine, to store data according to the data storage reference and the data length, including assigning a base storage address for the data storage reference; sending, by one or more of the target DMA engines, an acknowledgment message acknowledging that all the target DMA engines are prepared to receive a data transmission from the origin DMA engine; receiving, by the origin DMA engine, the acknowledgement message from the one or more of the target DMA engines; and transferring, by the origin DMA engine, data to data storage on each of the target compute nodes according to the data storage reference using a single direct put operation.

Archer, Charles J.; Blocksome, Michael A.

2012-12-11

218

Multiagent Collaboration in Directed Improvisation  

Microsoft Academic Search

Directed improvisation is a new paradigm for multiagent interaction. One or more human users direct one or more computer characters with scripted or interactive directions. The characters work together to improvise a course of behavior that follows the directions, expresses their distinctive individual styles, honors social conventions, and meets other objectives. The resulting \\

Barbara Hayes-roth; Lee Brownston; Robert Van Gent

1995-01-01

219

Growth directions of microstructures in directional solidification of crystalline materials  

NASA Astrophysics Data System (ADS)

In directional solidification, as the solidification velocity increases, the growth direction of cells or dendrites rotates from the direction of the thermal gradient to that of a preferred cristalline orientation. Meanwhile, their morphology varies with important implications for microsegregation. Here, we experimentally document the growth directions of these microstructures in a succinonitrile alloy in the whole accessible range of directions, velocities, and spacings. For this, we use a thin sample made of a single crystal on which the direction of the thermal gradient can be changed. This allows a fine monitoring of the misorientation angle between thermal gradient and preferred crystalline orientation. Data analysis shows evidence of an internal symmetry which traces back to a scale invariance of growth directions with respect to a Pclet number. This enables the identification of the relationship between growth directions and relevant variables, in fair agreement with experiment. Noticeable variations of growth directions with misorientation angles are evidenced and linked to a single parameter.

Deschamps, J.; Georgelin, M.; Pocheau, A.

2008-07-01

220

Growth directions of microstructures in directional solidification of crystalline materials.  

PubMed

In directional solidification, as the solidification velocity increases, the growth direction of cells or dendrites rotates from the direction of the thermal gradient to that of a preferred cristalline orientation. Meanwhile, their morphology varies with important implications for microsegregation. Here, we experimentally document the growth directions of these microstructures in a succinonitrile alloy in the whole accessible range of directions, velocities, and spacings. For this, we use a thin sample made of a single crystal on which the direction of the thermal gradient can be changed. This allows a fine monitoring of the misorientation angle between thermal gradient and preferred crystalline orientation. Data analysis shows evidence of an internal symmetry which traces back to a scale invariance of growth directions with respect to a Pclet number. This enables the identification of the relationship between growth directions and relevant variables, in fair agreement with experiment. Noticeable variations of growth directions with misorientation angles are evidenced and linked to a single parameter. PMID:18763966

Deschamps, J; Georgelin, M; Pocheau, A

2008-07-30

221

Future technical directions  

NASA Astrophysics Data System (ADS)

The areas of more recent technical advances are discussed. These are necessarily limited to those areas approved for public dissemination. The presentation is organized as follows: new directions in the Space Shuttle Main Engine (SSME); Computational Fluid Dynamics (CFD) advances; and other areas of technology advances. The advances in the SSME are focused on the continued support to reliable flights with additional benefits in lower cost and improved robustness. In the area of CFD, significant advances are made and emphasis is placed on further reductions in time and cost to perform the complex CFD in product design organizations. The need to better understand and analyze the reality of the environments and products that are designed are discussed. This includes emphasis on dynamic loads; probabilistic as well as deterministic loads, material properties, and hardware variations; and such real property effects as the existence of flaws. Each area represents significant challenges to the engineer of the future.

Jackson, Eugene D.; Sindir, Munir

222

Fiber optic TV direct  

NASA Astrophysics Data System (ADS)

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.

Kassak, John E.

1991-12-01

223

Microfluidic Compartmentalized Directed Evolution  

PubMed Central

Summary Directed evolution studies often make use of water-in-oil compartments, which conventionally are prepared by bulk emulsification, a crude process that generates non-uniform droplets and can damage biochemical reagents. A microfluidic emulsification circuit was devised that generates uniform water-in-oil droplets (21.9 0.8 ?m radius) with high throughput (107108 droplets per hour). The circuit contains a radial array of aqueous flow nozzles that intersect a surrounding oil flow channel. This device was used to evolve RNA enzymes with RNA ligase activity, selecting enzymes that could resist inhibition by neomycin. Each molecule in the population had the opportunity to undergo 108-fold selective amplification within its respective compartment. Then the progeny RNAs were harvested and used to seed new compartments. During five rounds of this procedure, the enzymes acquired mutations that conferred resistance to neomycin and caused some enzymes to become dependent on neomycin for optimal activity.

Paegel, Brian M.; Joyce, Gerald F.

2010-01-01

224

Site directed recombination  

SciTech Connect

Enhanced homologous recombination is obtained by employing a consensus sequence which has been found to be associated with integration of repeat sequences, such as Alu and ID. The consensus sequence or sequence having a single transition mutation determines one site of a double break which allows for high efficiency of integration at the site. By introducing single or double stranded DNA having the consensus sequence flanking region joined to a sequence of interest, one can reproducibly direct integration of the sequence of interest at one or a limited number of sites. In this way, specific sites can be identified and homologous recombination achieved at the site by employing a second flanking sequence associated with a sequence proximal to the 3'-nick.

Jurka, Jerzy W. (Los Altos, CA)

1997-01-01

225

Directed light fabrication  

SciTech Connect

Directed Light Fabrication (DLF) is a rapid prototyping process being developed at Los Alamos National Laboratory to fabricate metal components. This is done by fusing gas delivered metal powder particles in the focal zone of a laser beam that is, programmed to move along or across the part cross section. Fully dense metal is built up a layer at a time to form the desired part represented by a 3 dimensional solid model from CAD software. Machine ``tool paths`` are created from the solid model that command the movement and processing parameters specific to the DLF process so that the part can be built one layer at a time. The result is a fully dense, near net shape metal part that solidifies under rapid solidification conditions.

Lewis, G.K.; Nemec, R.; Milewski, J.; Thoma, D.J.; Cremers, D.; Barbe, M.

1994-09-01

226

Nocturia: new directions.  

PubMed

The Nocturia Think Tank (TT) met during the 2010 meeting of the International Consultation on Incontinence-Research Society to discuss present knowledge and future directions in care and research of this prominent component of the spectrum of lower urinary tract symptoms. Questions raised included whether nocturia should be re-defined as a function of its bother, effects on quality of life, and economic impact upon society. At issue is the need to delineate the determinants of successful nocturia management. The multifactorial nature of nocturia requires that progress in its treatment will be dependent upon the cooperative investigation on the part of urologists, urogynecologists, geriatricians, epidemiologists, medical economists and pharma. Areas for future avenues of research were outlined at the conclusion of the meeting. PMID:21661016

Weiss, Jeffrey P; Wein, Alan J; van Kerrebroeck, Philip; Dmochowski, Roger; Fitzgerald, Marypat; Tikkinen, Kari A O; Abrams, Paul

2011-06-01

227

Directionally positionable neutron beam  

SciTech Connect

Disclosed is apparatus for forming and directionally positioning a neutron beam. The apparatus includes an enclosed housing rotatable about a first axis with a neutron source axially positionable on the axis of rotation of the enclosed housing but rotationally fixed with respect to the housing. The rotatable housing is carried by a vertically positionable arm carried on a mobile transport. A collimator is supported by the rotatable housing and projects into the housing to orientationally position its inlet window at an adjustably fixed axial and radial spacing from the neutron source so that rotation of the enclosed housing causes the inlet window to rotate about a circle which is a fixed axial distance from the neutron source and has the axis of rotation of the housing as its center.

Bumgardner, H.M.; Dance, W.E.

1981-11-10

228

Directed quantum communication  

NASA Astrophysics Data System (ADS)

We address the question of whether there is a way of characterizing the quantum information transport properties of a medium or material. For this analysis, the special features of quantum information have to be taken into account. We find that quantum communication over an isotropic medium, as opposed to classical information transfer, requires the transmitter to direct the signal toward the receiver. Furthermore, for large classes of media there is a threshold, in the sense that sufficiently much of the signal has to be collected. Therefore, the medium's capacity for quantum communication can be characterized in terms of how the sizes of the transmitter and receiver have to scale with the transmission distance to maintain quantum information transmission. To demonstrate the applicability of this concept, an n-dimensional spin lattice is considered, yielding a sufficient scaling of ?n/3 with the distance ?.

berg, J.; Hengl, S.; Renner, R.

2013-03-01

229

Modelling directional solidification  

NASA Astrophysics Data System (ADS)

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.

Wilcox, William R.

1990-02-01

230

An antenna to direct light to opposite directions  

NASA Astrophysics Data System (ADS)

We propose that the split ring resonator can be used as an optical antenna to direct light emitted by an electric source to opposite directions at different wavelengths. We demonstrate the directional effects through numerical simulations and explain the phenomena by a two-dipole model. The performance of the antenna can be improved by putting the emitter in a super emitter structure.

Jie, Yao; Li, Yang; Yonghong, Ye

2013-07-01

231

Undoped and boron doped diamond nanoparticles as platinum and platinum-ruthenium catalyst support for direct methanol fuel cell application  

NASA Astrophysics Data System (ADS)

Nanoparticular diamond is a promising material that can be used as a robust and chemically stable catalytic support. It has been studied and characterized physically and electrochemically, in its powder and thin film forms. This thesis work intends to demonstrate that undoped diamond nanoparticles (DNPs) and boron-doped diamond nanoparticles (BDDNPs) can be used as an electrode and a catalytic support material for platinum and ruthenium catalysts. The electrochemical properties of diamond nanoparticle electrodes, fabricated using the ink paste method, were investigated. As an initial step, we carried out chemical purification of commercially available undoped DNPs by refluxing in aqueous HNO3 as well as of BDDNPs which were doped through a collaborative work with the University of Missouri. The purified material was characterized by spectroscopic and surface science techniques. The reversibility of reactions such as ferricyanide/ferrocyanide (Fe(CN) 63-/Fe(CN)64-) and hexaamineruthenium (III) chloride complexes as redox probes were evaluated by cyclic voltammetry at the undoped DNPs and BDDNPs surface. These redox probes showed limited peak currents and presented linear relationships between current (i) and the square root of the potential scan rate (v1/2). However, compared to conventional electrodes, the peak currents were smaller. BDDNPs show an improvement in charge transfer currents when compared to undoped DNPs. Platinum and ruthenium nanoparticles were chemically deposited on undoped DNPs and BDDNPs through the use of the excess of a mild reducing agent such NaBH4. In order to improve the nanoparticle dispersion sodium dodecyl benzene sulfonate (SDBS), a surfactant agent, was used. Percentages of platinum and ruthenium metals were varied as well as the stoichiometric amount of the reducing agent to determine adequate parameters for optimum performance in methanol oxidation. Both before and after the reducing process the samples were characterized by scanning electron microscopy (SEM), energy dispersive analysis (EDX), infrared spectroscopy (IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), prompt gamma neutron activation analysis (PGNAA), and X-ray photoelectron spectroscopy (XPS). In order to demonstrate the utility of the catalyst obtained, the samples were tested in an electrochemical cell using methanol as a probe solution. As was performed with the undoped DNPs and BDDNPs, the ink paste method was used to prepare the electrodes with Pt/DNP, Pt-Ru/DNP, Pt/BDDNP and Pt-Ru/BDDNP catalytic systems, to perform the electrochemical experiments. The Pt and Pt-Ru modified diamond electrodes were tested with cyclic voltammetry in 0.5 M H2SO4 as electrolyte support showing hydrogen adsorption/desorption at platinum surfaces. CO gas adsorption/desorption experiments were also performed to determine the active surface area of Pt when Ru is present. Methanol oxidation current peaks were obtained when the electrodes were tested in a 1.0 M methanol/0.5 M H2SO4 solution. The experimental results demonstrated that diamond nanoparticles are useful as an electrode material. A fuel cell is a device which transforms the chemical energy of a fuel directly into electrical energy. As previously mentioned, the aim of this research is to demonstrate the utility of undoped DNPs and BDDNPs as catalytic supports, which was performed by testing the catalytic systems obtained in a single fuel cell station at different temperatures to observe the cell performance.

La Torre Riveros, Lyda

232

Nano-particulate dispersion and reinforcement of nanostructured composite materials  

NASA Astrophysics Data System (ADS)

This research investigated the feasibility of reinforcing polymer composites using 30 nm SiC nanoparticles in a vinyl ester resin. The SiC nanoparticles were examined using transmission electron microscopy and thermogravimetric analysis. Gamma-methacryloxy propyl trimethoxy silane (MPS) was chosen as the coupling agent. Both mixing procedures with (1) the nanoparticles pretreated with a dilute MPS solution in an acid 5% (v/v) water-ethanol mixture and (2) the MPS sonicated as an integral blend with the filled vinyl ester, were attempted. Fourier transform infrared spectroscopy was used to study the silanol condensation between MPS and the SiC nanoparticles. The results show that ultrasonic mixing did not fully disperse the particles. Hence the composite strength did not improve although the modulus increased. The use of MPS improved the dispersion quality and hence the composite strength. The rheological behavior of SiC nanoparticle-filled vinyl ester resin systems was evaluated in terms of the Bingham, power law, Herschel-Bulkley, and Casson models. Even when the particle loading was less then 4% by weight, the viscosity of the nanoparticle suspension was found to increase much more than that of a microparticle suspension. This phenomenon may be the result of association between nanoparticles and polymer molecules, effectively making the nanoparticles larger. The resulting reduction in the mobility of polymer molecules also led to delayed curing. The maximum particle loading corresponding to infinite viscosity was determined as 0.1 volume fraction using the (1 - eta r-1/2) - ? dependence. The experimental optimum fractional weight per cent of the dispersants (wt. % dispersant/wt. % SiC) was found to be around 40% for 30 nm SiC nanoparticles, which is in close agreement with the theoretically calculated monolayer coverage dosage of 67%.

Yong, Virginia Hiu-Hung

2005-12-01

233

Nanoparticulated quercetin in combating age related cerebral oxidative injury.  

PubMed

Reactive oxygen species e.g. O(2)(*-), H(2)O(2) and *OH generated by the induction of oxidative stress exert a potential threat on the activity of endogenous antioxidant enzymes and substantially influence the aging process and age-dependant neuropathology. Chemical antioxidant is almost ineffective in protecting neuronal cells from oxidative damage as Blood Brain Barrier exists in between blood and brain interstitial fluid that restricts undegradable influx from the circulation into cerebral region. Quercetin (QC), a flavonoidal antioxidant is known as a potent antioxidant for its polyphenolic configuration. Formulation of QC in polylactide nanocapsule has been done and the efficacy of this vesicular flavonoid has been tested against cerebral ischemia induced oxidative damage in young and old rat brains. Antioxidant potential of QC loaded in nanocapsule (QC 7.2 mmol/kg b.wt., size 50 nm) was investigated by an in vivo model of cerebral ischemia and reperfusion on Sprague Dawley young (2 months, b.wt. 160-180 g) and aged (20 months, b.wt. 415-440 g) rats. Diene level, the index of lipid peroxidation and GSSG/GSH ratio were found to be higher in normal aged, compared to normal young rat brain. Endogenous antioxidants activities were lower in aged rat brain compared to young. Further reduction of these antioxidants were observed in aged rat brain by the induction of cerebral ischemia - reperfusion. Nanocapsule encapsulated QC treatment resulted a significant protection to endogenous antioxidant enzymes against ischemia induced oxidative damage in neuronal cells of young and old rats. PMID:20021389

Das, Sanchari; Mandal, Ardhendu K; Ghosh, Aparajita; Panda, Subhamay; Das, Nirmalendu; Sarkar, Sibani

2008-12-01

234

199. Plasmid DNA Delivery by Nanoparticule Loaded Coronary Stent  

Microsoft Academic Search

Introduction: Cardiovascular gene therapy has been hampered by a lack of effective gene delivery system. Although stent-based percutaneous gene delivery showed great promising, insufficient gene loading on stents remains a big problem. In this paper, we reported a new approach that gene loaded dodecylated chitosan nanoparticles (DCDNPs) were tethered on coronary stent and demonstrated efficient and highly localized plasmid DNA

Cunxian Song; Xu Jin; Dunwan Zhu; Chao Zhang; Hongfan Sun; Linhua Zhang; Kangde Yao

2006-01-01

235

Photodegradation of Lecithin Liposomes by Nanoparticulate Titanium Dioxide  

Microsoft Academic Search

Lecithin liposomes were studied by transmission electron microscopy (TEM), selected?area electron diffraction (SAED), IR, and GC?MS. Results indicate that titanium dioxide (TiO2) nanoparticles can gain access into lecithin liposomes during sonication and the lecithin liposomes can be effectively decomposed upon illumination with near?UV light.

Aihua Zou; Qiang Gu; Jing Wang; Chunwei Yuan; Rong Guo

2003-01-01

236

Pharmacokinetic change of nanoparticulate formulation "Lactosome" on multiple administrations.  

PubMed

Lactosome, which is a polymer micelle composed of poly(lactic acid)-b-poly(sarcosine), was applied successfully for solid tumor imaging. Lactosome is considered to escape from the reticuloendothelial system recognition, and shows prolonged in vivo blood clearance time. In vivo disposition of Lactosome, however, changed upon multiple dosages. Lactosome at the 2nd dosage was cleared from the blood stream by trapping at liver. This accelerated blood clearance (ABC) phenomenon is explained by production of anti-Lactosome IgM and IgG(3) through the immune response related with B-lymphocyte cells. The memory effect of B-lymphocyte cells lasted nearly for six months in mouse. The epitope moiety of Lactosome is concluded to be poly(sarcosine) based on the competitive inhibition assay. Since the ABC phenomenon was also reported with PEGylated liposome, nanoparticles in general may be potential in triggering the immune system. PMID:22841811

Hara, Eri; Makino, Akira; Kurihara, Kensuke; Yamamoto, Fumihiko; Ozeki, Eiichi; Kimura, Shunsaku

2012-07-27

237

Dual-nanoparticulate-reinforced aluminum matrix composite materials  

NASA Astrophysics Data System (ADS)

Aluminum (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nano-SiC) were fabricated by mechanical ball milling, followed by hot-pressing. Nano-SiC was used as an active mixing agent for dispersing the CNTs in the Al powder. The hardness of the produced composites was dramatically increased, up to eight times higher than bulk pure Al, by increasing the amount of nano-SiC particles. A small quantity of aluminum carbide (Al4C3) was observed by TEM analysis and quantified using x-ray diffraction. The composite with the highest hardness values contained some nanosized Al4C3. Along with the CNT and the nano-SiC, Al4C3 also seemed to play a role in the enhanced hardness of the composites. The high energy milling process seems to lead to a homogeneous dispersion of the high aspect ratio CNTs, and of the nearly spherical nano-SiC particles in the Al matrix. This powder metallurgical approach could also be applied to other nanoreinforced composites, such as ceramics or complex matrix materials.

Kwon, Hansang; Cho, Seungchan; Leparoux, Marc; Kawasaki, Akira

2012-06-01

238

Increased osteoblast adhesion on nanoparticulate crystalline hydroxyapatite functionalized with KRSR  

PubMed Central

The present in vitro study created nanometer crystalline hydroxyapatite (HA) and amorphous calcium phosphate for novel orthopedic applications. Specifically, nano-crystalline HA and amorphous calcium phosphate nanoparticles were synthesized by a wet chemical process followed by hydrothermal treatment for 2 hours at 200C and 70C, respectively. Resulting particles were then pressed into compacts. For the preparation of control conventional HA particles (or those currently used in orthopedics with micron diameters), the aforementioned calcium phosphate particles were pressed into compacts and sintered at 1100C for 2 hours. All calcium phosphate-based particles were fully characterized. Results showed that although there was an initial weight gain for all the compacts studied in this experiment, higher eventual degradation rates up to 3 weeks were observed for nano-amorphous calcium phosphate compared with nano-crystalline HA which was higher than conventional HA. Peptide functionalization (with the cell adhesive peptide lysine-arginine-serine-arginine [KRSR] and the non-cell-adhesive peptide lysine-serine-arginine-arginine [KSRR]) was accomplished by means of a three-step reaction procedure: silanization with 3-aminopropyltriethoxysilane (APTES), cross-linking with N-succinimidyl-3-maleimido propionate (SMP), and finally peptide immobilization. The peptide functionalization was fully characterized. Results demonstrated increased osteoblast (bone-forming cell) adhesion on non-functionalized and functionalized nano-crystalline HA compacts compared with nano amorphous calcium phosphate compacts; both increased osteoblast adhesion compared with conventional HA. To further exemplify the novel properties of nano crystalline HA, results also showed similar osteoblast adhesion between non-functionalized nano crystalline HA and KRSR functionalized conventional HA. Thus, results provided evidence that nanocrystalline HA should be further studied for orthopedic applications.

Nelson, Michael; Balasundaram, Ganesan; Webster, Thomas J

2006-01-01

239

Nanoparticulate Adjuvants and Delivery Systems for Allergen Immunotherapy  

PubMed Central

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.

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

2012-01-01

240

Evaluation of Hydrophobic Nanoparticulate Delivery System for Insulin  

PubMed Central

Insulin loaded hydrophobic nanoparticles were prepared by solvent diffusion followed by lyophilization. Nanoparticles were characterized for mean size by dynamic laser scattering and for shape by scanning electron microscopy. Insulin encapsulation efficiency, in vitro stability of nanoparticles in presence of proteolytic enzymes and in vitro release were determined by high pressure liquid chromatography analysis. The biological activity insulin from the nanopraticles was estimated by enzyme-linked immunosorbant assay and in vivo using Wister diabetic rats. Nanoparticles ranged 0.5260.071 ?m in diameter. Insulin encapsulation efficiency was 95.71.2%. Insulin hydrophobic nanoparticles suppressed insulin release promoted sustained release in pH 7.4 phosphate buffer and shown to protect insulin from enzymatic degradation in vitro in presence of chymotripsin. Nanoencapsulated insulin was bioactive, demonstrated through both in vivo and in vitro.

Singnurkar, P. S.; Gidwani, S. K.

2008-01-01

241

Identification of Directional Couplings  

NASA Astrophysics Data System (ADS)

An important piece of information, which can be extracted from parameters of empirical models, is quantitative characteristics of couplings between processes under study. The problem of coupling detection is encountered in multiple fields including physics (Bezruchko et al., 2003), geophysics (Maraun and Kurths, 2005; Mokhov and Smirnov, 2006, 2008; Mosedale et al., 2006; Palus and Novotna, 2006; Verdes, 2005; Wang et al., 2004), cardiology (Rosenblum et al., 2002; Palus and Stefanovska, 2003) and neurophysiology (Arnhold et al., 1999; Brea et al., 2006; Faes et al., 2008; Friston et al., 2003; Kreuz et al., 2007; Kiemel et al., 2003; Le Van Quyen et al., 1999; Mormann et al., 2000; Osterhage et al., 2007; Pereda et al., 2005; Prusseit and Lehnertz, 2008; Smirnov et al., 2005; Romano et al., 2007; Schelter et al., 2006; Schiff et al., 1996; Sitnikova et al., 2008; Smirnov et al., 2008, Staniek and Lehnertz, 2008; Tass, 1999; Tass et al., 2003). Numerous investigations are devoted to synchronisation, which is an effect of interaction between non-linear oscillatory systems (see, e.g., Balanov et al., 2008; Boccaletti et al., 2002; Hramov and Koronovskii, 2004; Kreuz et al., 2007; Maraun and Kurths, 2005; Mormann et al., 2000; Mosekilde et al., 2002; Osipov et al., 2007; Palus and Novotna, 2006; Pikovsky et al., 2001; Prokhorov et al., 2003; Tass et al., 2003). In the last decade, more careful attention is paid to directional coupling analysis. Such characteristics might help, e.g., to localise an epileptic focus (a pathologic area) in the brain from electroencephalogram (EEG) or magnetoencephalogram (MEG) recordings: hypothetically, an increasing influence of an epileptic focus on adjacent areas leads to the seizure onset for some kinds of epilepsy.

Bezruchko, Boris P.; Smirnov, Dmitry A.

242

California Agricultural Direct Marketing Study.  

National Technical Information Service (NTIS)

The California Agricultural Direct Marketing Survey (CADMS) represents a first step by the California Institute for Rural Studies to build a more solid foundation for understanding the relative importance of direct marketing (DM) for California's farmers,...

C. L. Shelley K. M. Kambara

2002-01-01

243

Channel redistribution with direct selling  

Microsoft Academic Search

It seems nowadays that a company can be considered either a pure-direct such as Amazon.com and Dell Computers, or an adopted-direct, like Barnes and Noble for example. An adopted-direct companys decision to directly sell on-line has become a fashionable choice. But the results of such choice differ drastically. Glorious success mixed with pathetic failure. One of the pending issues has

Dong-qing Yao; John J. Liu

2003-01-01

244

Directional detector of gamma rays  

DOEpatents

A directional detector of gamma rays comprises a strip of an electrical cuctor of high atomic number backed with a strip of a second electrical conductor of low atomic number. These elements are enclosed within an electrical conductor that establishes an electrical ground, maintains a vacuum enclosure and screens out low-energy gamma rays. The detector exhibits a directional sensitivity marked by an increased output in the favored direction by a factor of ten over the output in the unfavored direction.

Cox, Samson A. (Downers Grove, IL); Levert, Francis E. (Chicago, IL)

1979-01-01

245

Directional overcurrent relaying (67) concepts  

Microsoft Academic Search

Directional overcurrent relaying (67) refers to relaying that can use the phase relationship of voltage and current to determine direction to a fault. There are a variety of concepts by which this task is done. This paper will review the mainstream methods by which 67 type directional decisions are made by protective relays. The paper focuses on how a numeric

J. Horak

2006-01-01

246

Strategic Defense Initiative Organization. Directive  

SciTech Connect

The Directive reissues DoD Directive 5141.5, February 21, 1986, and establishes, pursuant to the authority vested in the Secretary of Defense under Title 10, United States Code, and National Security Decision Directive 119, January 6, 1984, the Strategic Defense Initiative Organization as an agency of the Department of Defense with responsibilities, functions, relationships, and authorities as prescribed herein.

Furtner, R.

1987-06-04

247

Direct Democracy for Transition Countries  

Microsoft Academic Search

Theoretical arguments and empirical evidence are advanced to bolster the claim that direct political participation via referenda and initiatives constitutes an advanced form of democracy with beneficial effects on Transition Countries. Direct democracy raises trust and honesty and improves social outcomes. Per capita incomes and subjective well-being are raised. Standard arguments against direct democracy (citizens' incompetence and lacking interest, danger

Bruno S. Frey

2003-01-01

248

New directions at NSF  

NASA Astrophysics Data System (ADS)

The mission and scope of the National Science Foundation (NSF) and lightwave technology will be very briefly discussed. The focus of the presentation will be directed toward changes in research support that are taking place and the opportunities we have for aiming our research to meet the challenges and needs that face the nation. In the USA it is very clear that defense oriented research is downsizing and is being redirected into economy driven aresas, such as manufacturing, business, and industry. For those researchers who are willing to move into these areas and find a niche, the rewards may be very great. Industrial research partners should also seize these opportunities to enhance their resources in an otherwise bleak future for industrial support of basic research in lightwave technology and many other reserach disciplines. These activities of bringing together industry and academia will have the value added benefit of providing increased job opportunities for students. An outline of some of these opportunities and incentives will be presented. On the international front, there has never been a better time for the encouragement of joint research and collaboration across borders. The economic potential for involvement in Eastern Europe and Asia are enormous. Agencies like ourselves are open to help support of visiting scientist/engineer exchange, international conferences and forums and support of innovative ideas to help further enhance economic developemnt of the world and hence the quality of life. The presence of the Russian delegation here at these SPIE meetings in in part the result of NSF support. Concomitant with these changes is a growing interest in education. Academia is gradually realizing that education includes training for students to acquire jobs and hence we complete the cycle of the importance of interacting with industry. At the NSF a major new initiative is being introduced in Optical Science and Engineering (OSE). This effort has been created as an outgrowth of the NRC study being conducted in parallel under the same name. OSE is based on the fact that optics is a very interdisciplinary area and special emphasis on the interface between the relevant areas is where the action is. Lightwave technology and the implementation of organic materials to optoelectronic applications is clearly an area which has tremendous potential for economic impact and it fits the criteria for the OSE initiative. It is also exciting, challenging, and personally rewarding. But organic materials have been promising for quite some time and some are getting impatient. To provide credibility to those who support this research (governement, idustry, etc.), we must turn our attention to ways in which we can accelerate the transition from the laboratory discovery to the consumer. In this way everyone will become a winner.

Harvey, Albert B.

1995-10-01

249

NeoModus: Direct Connect  

NSDL National Science Digital Library

Direct Connect is an online file-sharing community. The important feature in Direct Connect is that there is no main data center or master server. The users themselves provide the network architecture. Direct Connect software has two modules - the client and the hub. You can use the Direct Connect client to download files from other users in the Direct Connect network. The hub allows you to share multiple directories from your local and mapped directories with other users. Direct Connect has a user-friendly interface which provides integrated searching, graphical navigation of files, and public and private chatting. It can also be set to shut down automatically after all transfers have been completed. Direct Connect client and hub are available for download from the site. Please note that this program is advertiser supported and some non-personally identifiable information is collected. Concerned users should consult the site's privacy policy.

250

Crystal anisotropy and growth directions in directional solidification  

NASA Astrophysics Data System (ADS)

In directional solidification, the growth directions of cells and dendrites into the melt vary with the pulling velocity from the direction of the thermal gradient to that of a principal crystalline axis. We experimentally determine them in a succinonitrile alloy in the whole available range of variables. Data reveal a non-linear collapse onto a master curve that synthetizes the orientational response of cells and dendrites to the growth conditions.

Deschamps, J.; Georgelin, M.; Pocheau, A.

2006-10-01

251

The CO tolerance pathways on the PtRu electrocatalytic system  

Microsoft Academic Search

This work presents results of the studies of the CO tolerance of Pt\\/C, Ru\\/C, Pt\\/C+Ru\\/C and PtRu\\/C forming different electrode assemblies for the hydrogen oxidation reaction (HOR) in polymer electrolyte fuel cells. Anodes consisting of the physical mixtures of Pt\\/C+Ru\\/C in two distinct configurations were used to elucidate the Ru effects on the HOR electrocatalysis of Pt in the presence

Pietro P. Lopes; Edson A. Ticianelli

2010-01-01

252

Directivity of railway noise sources  

NASA Astrophysics Data System (ADS)

In the Harmonoise project the description of vertical and horizontal directivities of railway noise sources has been required. Other features of the source description are sound power level spectra in one-third octave bands as a function of speed and the physical location of the different sound sources. Based on systematic investigations methods to measure and to determine the directivities of railway noise sources are presented in this paper. The determination of the directivity of rolling noise is discussed in detail. For the directivities of traction noise and aerodynamic noise the discussion is more analytical because of limited access to relevant data. For each type of main railway noise source, i.e. rolling noise, traction noise and aerodynamic noise, default directivity functions are proposed for the use in the source description of railway noise. These default directivity functions will be subject to revisions when more accurate data become available.

Zhang, Xuetao; Jonasson, Hans G.

2006-06-01

253

Frame theory in directional statistics  

Microsoft Academic Search

Distinguishing between uniform and non-uniform sample distributions is a common problem in directional data analysis; however for many tests, non-uniform distributions exist that fail uniformity rejection. By merging directional statistics with frame theory, we find that probabilistic tight frames yield non-uniform distributions that minimize directional potentials, leading to failure of uniformity rejection for the Bingham test. Finally, we apply our

Martin Ehler; Jennifer Galanis

2010-01-01

254

Median recoil direction as a WIMP directional detection signal  

SciTech Connect

Direct detection experiments have reached the sensitivity to detect dark matter weakly interacting massive particles (WIMPs). Demonstrating that a putative signal is due to WIMPs, and not backgrounds, is a major challenge, however. The direction dependence of the WIMP scattering rate provides a potential WIMP 'smoking gun'. If the WIMP distribution is predominantly smooth, the Galactic recoil distribution is peaked in the direction opposite to the direction of Solar motion. Previous studies have found that, for an ideal detector, of order 10 WIMP events would be sufficient to reject isotropy, and rule out an isotropic background. We examine how the median recoil direction could be used to confirm the WIMP origin of an anisotropic recoil signal. Specifically, we determine the number of events required to confirm the direction of solar motion as the median inverse recoil direction at 95% confidence. We find that for zero background 31 events are required, a factor of {approx}2 more than are required to simply reject isotropy. We also investigate the effect of a nonzero isotropic background. As the background rate is increased the number of events required increases, initially fairly gradually and then more rapidly, once the signal becomes subdominant. We also discuss the effect of features in the speed distribution at large speeds, as found in recent high resolution simulations, on the median recoil direction.

Green, Anne M. [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom); Morgan, Ben [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom)

2010-03-15

255

The Influence of Directional Associations on Directed Forgetting and Interference  

Microsoft Academic Search

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 List 2 (chip ? chisel),

Lili Sahakyan; Leilani B. Goodmon

2007-01-01

256

The Influence of Directional Associations on Directed Forgetting and Interference  

ERIC Educational Resources Information Center

|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

Sahakyan, Lili; Goodmon, Leilani B.

2007-01-01

257

Telecoil: Connecting Directly to Sound  

MedlinePLUS

... Telecoil Connecting Directly to Sound ? What is hearing assistive technology? (HAT) There are three types of wireless hearing assistive technology discussed here: ? The hearing loop a wire that ...

258

Direct cooled power electronics substrate  

DOEpatents

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.

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

2010-09-14

259

Electrochemical and XRD characterization of platinum-ruthenium blacks for DMFC anodes.  

SciTech Connect

It is generally accepted that Pt-Ru alloy catalysts with an atomic Pt-to-Ru ratio of 1:1 generate the best anode perform'ance in the direct methanol fuel cell (DMFG). However, at near-ambient cell operating temperatures, Gasteiger et al. reported that a catalyst with significantly lower Ru content, {approx} 10 at %, offers the highest activity towards methanol. Recently, Dinh et al. demonstrated that the activity of different Pt-Ru catalysts with the same Pt-to-Ru atomic ratio in the bulk might vary depending on the actual surface composition, which is often significantly different from that in the bulk phase, In this work, we study several experimental Pt-Ru catalysts (Johnson Matthey) with Pt-to-Ru atomic ratio ranging from 9: 1 to 1 :2. Electrocatalytic activity of these catalysts in methanol oxidation reaction is investigated in a regular DMFC 'and probed using voltammetric stripping of surhce CO.

Eickes, C. (Christian); Brosha, E. L. (Eric L.); Garzon, F. H. (Fernando H.); Purdy, G. M. (Geraldine M.); Zelenay, P. (Piotr); Morita, T. (Takanari); Thompsett, D. (David)

2002-01-01

260

Optically broadcasting wind direction indicator  

NASA Astrophysics Data System (ADS)

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.

Zysko, Jan A.

1994-10-01

261

Direct Marketing Goes to College.  

ERIC Educational Resources Information Center

|The only form of marketing important to an admissions department, direct marketing, whose principal vehicle is direct mail, is identified as an organized method for sharing and distributing information to prospective students. Target audiences, marketing administration, and effective mailings are discussed. (MLW)|

Merante, Joseph A.

1980-01-01

262

Problematic Directives in Pedagogical Interaction  

ERIC Educational Resources Information Center

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

Waring, Hansun Zhang; Hruska, Barbara L.

2012-01-01

263

Coordination Science: Challenges and Directions  

Microsoft Academic Search

Several distinct kinds of coordination technology have evolved to support effective coordination in cooperative work. This paper reviews some of the major weaknesses with current coordination technology and suggests several technical directions for addressing these weaknesses. These directions include developing semi-structured process representations that explicitly capture cooperative work inter-dependencies, exploiting advanced product and software design technologies for process design, and

Mark Klein

1996-01-01

264

Statically balanced direct drive manipulator  

Microsoft Academic Search

A practical architecture, using a four-bar-linkage, is cgnsidered for the University of Minnesota direct drive robot (8). This statically- balanced direct drive robot has been constructed for stability analysis of the robot in constrained manipulation (5 -7). As a result of the elimination of the gravity forces (without any counter weights), smaller actuators and consequently smaller amplifiers were chosen. The

H. Kazerooni; S. Kim

1989-01-01

265

Adaptive smoothing respecting feature directions  

Microsoft Academic Search

Accurate extraction of the image feature directions is essential to image smoothing and other image processing tasks. We show that the gradient-based feature direction extraction method can be very erroneous. The gradient is too local, and it cannot detect oscillations. We have developed two new methods: the Hessian method, an approach using higher order differentia- tions, and the Gabor method,

Ren A. Carmona; Sifen Zhong

1998-01-01

266

The plasmonic folded directional coupler  

NASA Astrophysics Data System (ADS)

Folded Directional Couplers (FDCs) are compact two-port devices. They combine the properties of directional couplers and Fabry-Perot cavities. We describe the properties of the FDC in a plasmonic geometry. We develop a simple and quite accurate, semi-analytic model for the device. We show that such this design can lead to very compact couplers.

Nozhat, N.; McPhedran, R. C.; de Sterke, C. M.; Granpayeh, N.

2011-10-01

267

Efficient Placement of Directional Antennas  

SciTech Connect

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.

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

2010-09-20

268

Direct catastrophic injury in sports.  

PubMed

Catastrophic sports injuries are rare but tragic events. Direct (traumatic) catastrophic injury results from participating in the skills of a sport, such as a collision in football. Football is associated with the greatest number of direct catastrophic injuries for all major team sports in the United States. Pole vaulting, gymnastics, ice hockey, and football have the highest incidence of direct catastrophic injuries for sports in which males participate. In most sports, the rate of catastrophic injury is higher at the collegiate than at the high school level. Cheerleading is associated with the highest number of direct catastrophic injuries for all sports in which females participate. Indirect (nontraumatic) injury is caused by systemic failure as a result of exertion while participating in a sport. Cardiovascular conditions, heat illness, exertional hyponatremia, and dehydration can cause indirect catastrophic injury. Understanding the common mechanisms of injury and prevention strategies for direct catastrophic injuries is critical in caring for athletes. PMID:16272269

Boden, Barry P

2005-11-01

269

Direct \\  

Microsoft Academic Search

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

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

1973-01-01

270

Potential theory for directed networks.  

PubMed

Uncovering factors underlying the network formation is a long-standing challenge for data mining and network analysis. In particular, the microscopic organizing principles of directed networks are less understood than those of undirected networks. This article proposes a hypothesis named potential theory, which assumes that every directed link corresponds to a decrease of a unit potential and subgraphs with definable potential values for all nodes are preferred. Combining the potential theory with the clustering and homophily mechanisms, it is deduced that the Bi-fan structure consisting of 4 nodes and 4 directed links is the most favored local structure in directed networks. Our hypothesis receives strongly positive supports from extensive experiments on 15 directed networks drawn from disparate fields, as indicated by the most accurate and robust performance of Bi-fan predictor within the link prediction framework. In summary, our main contribution is twofold: (i) We propose a new mechanism for the local organization of directed networks; (ii) We design the corresponding link prediction algorithm, which can not only testify our hypothesis, but also find out direct applications in missing link prediction and friendship recommendation. PMID:23408979

Zhang, Qian-Ming; L, Linyuan; Wang, Wen-Qiang; Zhou, Tao

2013-02-11

271

Direct Simulation of Turbulent Combustion.  

National Technical Information Service (NTIS)

Direct Numerical Simulation (DNS) results obtained for premixed turbulent flames are presented and discussed to provide a description of the DNS possibilities and limitations. Numerical issues and boundary conditions are discussed. The basis of flamelet m...

T. J. Poinsot

1992-01-01

272

Dimensional Crossover in Directed Percolation.  

National Technical Information Service (NTIS)

We study the dimensional crossover in directed percolation in three dimensions. Bonds are allowed to have different concentrations along the three cartesian axes of the lattice. Through a Position Space Renormalization Group we obtain the phase-diagrams w...

A. M. N. Chame S. L. A. Queiroz R. R. Santos

1984-01-01

273

Launching Self-Directed Learners  

ERIC Educational Resources Information Center

Self-directed learning enables students to guide themselves and monitor their own progress towards specific goals. The positive approach towards self-management in developing alternative strategies to achieve the goals is discussed.

Costa, Arthur L.; Kallick, Bena

2004-01-01

274

Duplex Direct Data Distribution System.  

National Technical Information Service (NTIS)

The NASA Glenn Research Center (GRC) is developing and demonstrating communications and network technologies that are helping to enable the near-Earth space Internet. GRC envisions several service categories. The first of these categories is direct data d...

2001-01-01

275

Nonimaging radiant energy direction device  

DOEpatents

A raidant energy nonimaging light direction device is provided. The device includes an energy transducer and a reflective wall whose contour is particularly determined with respect to the geometrical vector flux of a field associated with the transducer.

Winston, Roland (Chicago, IL)

1980-01-01

276

Direct Broadcast Satellite: Radio Program  

NASA Astrophysics Data System (ADS)

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.

Hollansworth, James E.

1992-10-01

277

Directive Teaching in the Classroom  

ERIC Educational Resources Information Center

|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)|

Stephens, Thomas M.

1974-01-01

278

DRIFT COMPENSATED DIRECT COUPLED AMPLIFIER  

DOEpatents

An improved direct-coupled amplifier having zerolevel drift correction is described. The need for an auxiliary corrective-potential amplifier is eliminated thereby giving protection against overload saturation of the zero- level drift correcting circuit. (T.R.H.)

Windsor, A.A.

1959-05-01

279

Set-homogeneous directed graphs  

Microsoft Academic Search

A directed graph is set-homogeneous if, whenever U and V are isomorphic finite subdigraphs, there is an automorphism g of the digraph with U^g=V. Here, extending work of Lachlan on finite homogeneous digraphs, we classify finite set-homogeneous digraphs, where we allow some pairs of vertices to have arcs in both directions. Under the assumption that such pairs of vertices are

Robert Gray; Dugald Macpherson; Cheryl E. Praeger; Gordon F. Royle

2010-01-01

280

Set-homogeneous directed graphs  

Microsoft Academic Search

A directed graph is set-homogeneous if, whenever U and V are isomorphic finite subdigraphs, there is an automorphism g of the digraph with Ug=V. Here, extending work of Lachlan on finite homogeneous digraphs, we classify finite set-homogeneous digraphs, where we allow some pairs of vertices to have arcs in both directions. Under the assumption that such pairs of vertices are

Robert Gray; Dugald Macpherson; Cheryl E. Praeger; Gordon F. Royle

2010-01-01

281

Consumer Responses to Direct Selling  

Microsoft Academic Search

This paper describes findings from an investigation of consumers' experiences with and attitudes toward direct selling methods, based upon face-to-face interviews with 491 residents in three Pacific Northwest metropolitan areas. Demographic differences in purchase behavior and in preferences for different selling methods are reported, along with consumers' responses to open-ended questions concerning what they like and dislike about direct selling,

J. Thad Barnowe; David E. McNabb

1993-01-01

282

Directions for improved fusion reactors  

Microsoft Academic Search

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

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

1986-01-01

283

Quantum direct communication with authentication  

SciTech Connect

We propose two quantum direct communication (QDC) protocols with user authentication. Users can identify each other by checking the correlation of Greenberger-Horne-Zeilinger (GHZ) states. Alice can directly send a secret message to Bob without any previously shared secret using the remaining GHZ states after authentication. Our second QDC protocol can be used even though there is no quantum link between Alice and Bob. The security of the transmitted message is guaranteed by properties of entanglement of GHZ states.

Lee, Hwayean [Center for Information Security Technologies (CIST) and Graduate School of Information Security (GSIS), Korea University, Anam Dong, Sungbuk Gu, Seoul (Korea, Republic of); Institut fuer Experimentalphysik, Universitaet Wien (Austria); Lim, Jongin [Center for Information Security Technologies (CIST) and Graduate School of Information Security (GSIS), Korea University, Anam Dong, Sungbuk Gu, Seoul (Korea, Republic of); Yang, HyungJin [Center for Information Security Technologies (CIST) and Graduate School of Information Security (GSIS), Korea University, Anam Dong, Sungbuk Gu, Seoul (Korea, Republic of); Department of Physics, Korea University, Chochiwon, Choongnam (Korea, Republic of)

2006-04-15

284

31 CFR 357.26 - Direct Deposit.  

Code of Federal Regulations, 2011 CFR

...LEGACY TREASURY DIRECT Legacy Treasury Direct Book-Entry Securities System (Legacy Treasury Direct) § 357...on account. Where the Legacy Treasury Direct ® securities...Approved by the Office of Management and Budget under...

2013-07-01

285

Directive and Non-Directive Movement in Child Therapy.  

ERIC Educational Resources Information Center

Presents a new authorship method of child therapy based on visualization through motion. Maintains that this method stimulates motor development and musical receptiveness, and promotes personality development. Suggests that improvised movement to music facilitates the projection mechanism and that directed movement starts the channeling phase.

Krason, Katarzyna; Szafraniec, Grazyna

1999-01-01

286

Directions for improved fusion reactors  

SciTech Connect

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 reactors. A generic fusion physics/engineering/costing model is used to provide a quantiative basis for these arguments for specific fusion concepts.

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

1986-01-01

287

Directing: a complex systems perspective.  

PubMed

As systems evolve over time, their natural tendency is to become increasingly more complex. Studies in the field of complex systems have generated new perspectives on managing in social organizations such as hospitals. Much of this research appears as a natural extension of the cross-disciplinary field of systems theory. This is the third in a 5-part series on applying complex systems science to the traditional management concepts of planning, organizing, directing, coordinating, and controlling. In this article, the concept of directing is explored from a complex systems perspective. PMID:18300836

Clancy, Thomas R

2008-02-01

288

Directional spinals in obstetric analgesia.  

PubMed

Directional characteristics of spinal injections delivered via a 22 gauge Whitacre needle were confirmed in twenty-one obstetric patients undergoing elective Caesarean section. Caudad injection was inadequate for elective Caesarean section, while cephalad or lateral injection provided good sensory levels for the duration of the surgery. It is speculated that along with the low incidence of postspinal headache and ease of administering the block with a more rigid 22 gauge needle, low dose caudally directed injections may provide a superior means of administering saddle block analgesia for obstetric patients. PMID:637277

Graham, C W; Sutton, L; Cozen, H J

1978-02-01

289

Directional drilling and earth curvature  

SciTech Connect

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.

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

2000-03-01

290

Direct-Coupled-Resonator Filters  

Microsoft Academic Search

A new analysis is given of direct-coupled-resonator filters that results in excellent response at much greater bandwidths than has previously been possible. The method relies on the fact that the coupling elements can be made into perfect impedance inverters, or \\

Seymour Cohn

1957-01-01

291

Survey on Directed Model Checking  

Microsoft Academic Search

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

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

2008-01-01

292

Electromagnetic direct implicit PIC simulation  

SciTech Connect

Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

Langdon, A.B.

1983-03-29

293

Directing hair motion on Tangled  

Microsoft Academic Search

State-of-the-art simulation techniques can produce compelling and natural hair motion. In creating Disney's feature film Tangled, physically plausible motion was important but just one foundational component. The story contains an unprecedented amount of interaction of the hair with the characters, as well as a high level of art-direction. Through 2D \\

Maryann Simmons; Kelly Ward; Hidetaka Yosumi; Hubert Leo; Xinmin Zhao

2011-01-01

294

A Synchronised Direct Digital Synthesiser  

Microsoft Academic Search

We describe a Direct Digital Synthesiser (DDS) which provides three frequency-locked synchronised outputs to generate frequencies from DC to 160 MHz. Primarily designed for use in a heterodyning range imaging system, the flexibility of the design allows its use in a number of other applications which require any number of stable, synchronised high frequency outputs. Frequency tuning of 32 bit

A. D. Payne; D. A. Carnegie; A. A. Dorrington; M. J. Cree

295

Curriculum Change: Direction and Process.  

ERIC Educational Resources Information Center

|Four conference presentations in this report provide insights into and understandings of both the process of curriculum change and the direction that such change should take. Professor John I. Goodlad, in the first address, urges the development of a "humanistic curriculum." In the second presentation, Dr. William G. Hollister, a mental health

Leeper, Robert R., Ed.

296

New Directions in Curriculum Study.  

ERIC Educational Resources Information Center

In a discussion of new directions in curriculum study, alternatives to present patterns have been grouped under: (1) state and national studies, (2) articulation, (3) innovation in curriculum, (4) basic studies, (5) black studies, and (6) vocational education. A summary of major trends in curriculum development uses seven categories: (1) growth of

Park, Young

1971-01-01

297

Directed bondgraphs and integral matroids  

Microsoft Academic Search

The presentation of a theory for the mathematical foundations of the bondgraph mod- elling method is continued by this analysis of the combinatorial properties of directed bondgraphs (di-bondgraphs). This theory also provides a means to explore the relation- ship between a bondgraph model and a graph-theoretic model of the same system, as well as establishing a framework for developing a

S. H. Birkett

2009-01-01

298

Direct Simulation of Pathological Detonations  

Microsoft Academic Search

In previous papers we have demonstrated how the direct simulation Monte Carlo method can be used to simulate detonations. Those simulations were limited to exothermic reactions. In this paper exothermic and endothermic reactions are simulated. Under these circumstances, one obtains pathological detonations. That is, these simulations cannot be predicted using the well-known Chapman-Jouguet hypothesis. The details of these simulations can

James B. Anderson; Lyle N. Long

299

Direct Simulation of Pathological Detonations  

Microsoft Academic Search

In previous papers we have demonstrated how the direct simulation Monte Carlo method can be used to simulate detonations. Those simulations were limited to exothermic reactions. In this paper exothermic and endothermic reactions are simulated. Under these circumstances, one obtains pathological detonations. That is, these simulations cannot be predicted using the well-known Chapman-Jouguet hypothesis. The details of these simulations can

James B. Anderson; Lyle N. Long

2003-01-01

300

Direct firing downhole steam generator  

SciTech Connect

Direct firing downbole steam generator basically comprises an injector assembly axially connected with a combustion chamber. Downstream of the combustion chamber and oriented so as to receive its output is a heat exchanger wherein preheated water is injected into the heat exchanger through a plurality of one-way valves, vaporized and injected through a nozzle, packer and check valve into the well formation.

Binsley, R.L.; Wagner, W.R.; Wright, D.E.

1982-06-29

301

DIRECTIONAL VIRTUAL FENCING [DFV (TRADEMARK)  

Technology Transfer Automated Retrieval System (TEKTRAN)

A novel method is described for controlling free-ranging cows using Global Positioning System (GPS) technology and electromechanical cues delivered through a device termed Directional Virtual Fencing (DVFTM). The device is described as a tool to control animal movement, as well as a device to move ...

302

Direct methods for recovering motion  

Microsoft Academic Search

We have developed direct methods for recovering the motion of an observer in a static environment in th e case of pure rotation, pure translation, and arbitrary motion when the rotation is known . Some of thes e methods are based on the minimization of the difference between the observed time derivative of bright - ness and that predicted from

Berthold K. P. Horn; E. J. WELDON JR

1988-01-01

303

Direct Mailshots: The Gender Effect  

Microsoft Academic Search

Direct marketing can target individuals, but not merely according to name and address drawn from lists - it can also use different content and tone of voice. But is the 'gender effect' such that men and women should be targeted differently? This paper reports a research programme which explores this issue. Ten group discussions were conducted around the UK and

Agnes Nairn; Martin Evans

304

Direct Measurement of Light Waves  

Microsoft Academic Search

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

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

305

Direct flow crystal growth system  

DOEpatents

A crystal is grown in a constantly filtered solution which is flowed directly into the growing face of a crystal. In a continuous flow system, solution at its saturation temperature is removed from a crystal growth tank, heated above its saturation temperature, filtered, cooled back to its saturation temperature, and returned to the tank.

Montgomery, Kenneth E. (Tracy, CA); Milanovich, Fred P. (Lafayette, CA)

1992-01-01

306

Direct flow crystal growth system  

DOEpatents

A crystal is grown in a constantly filtered solution which is flowed directly into the growing face of a crystal. In a continuous flow system, solution at its saturation temperature is removed from a crystal growth tank, heated above its saturation temperatue, filtered, cooled back to its saturation temperature, and returned to the tank. 2 figs.

Montgomery, K.E.; Milanovich, F.P.

1989-10-30

307

New directions in migration research  

Microsoft Academic Search

This paper takes several surveys of the literature concerning migration research as its starting point and directs the reader toward a number of potentially fruitful lines for future research. Major sections include one on modeling migrant choice in which the pros and cons of using gross versus net migration measures are discussed. A second introduces and discusses the concept of

Michael J. Greenwood; Peter R. Mueser; David A. Plane; Alan M. Schlottmann

1991-01-01

308

Future Directions for Machine Learning  

Microsoft Academic Search

Summary In this paper we discuss possible future directions of research for soft computing in the context of artificial intelligence machine learning. Fundamental issues are presented with basic ideas emphasised rather than detailed accounts of algorithms and procedures. The use of fuzzy sets for machine learning, computer intelligence and creativity are discussed in relation to the central problems of creating

J. F. Baldwin

309

Direct firing downhole steam generator  

Microsoft Academic Search

A direct firing down-hole steam generator is composed of an injector assembly axially connected with a combustion chamber. Downstream of the combustion chamber and oriented so as to receive its output is a heat exchanger where preheated water is injected into the heat exchanger through a number of one-way valves. The heated water is vaporized and injected through a nozzle,

W. R. Wagner; D. E. Wright; R. L. Binsley

1982-01-01

310

Direct firing downhole steam generator  

Microsoft Academic Search

Direct firing downbole steam generator basically comprises an injector assembly axially connected with a combustion chamber. Downstream of the combustion chamber and oriented so as to receive its output is a heat exchanger wherein preheated water is injected into the heat exchanger through a plurality of one-way valves, vaporized and injected through a nozzle, packer and check valve into the

R. L. Binsley; W. R. Wagner; D. E. Wright

1982-01-01

311

Solar powered direct osmosis desalination  

Microsoft Academic Search

The paper deals with a novel solar powered water desalination technique based on direct osmosis process. The separation is driven by natural osmosis, which does not require external pumping energy as in the reverse osmosis process. Therefore, the specific power consumption of the desalination process is reduced from approximately 5 kWh\\/m3 for seawater reverse osmosis to a value of less

Rashid A. Khaydarov; Renat R. Khaydarov

2007-01-01

312

Training of Direct Service Staff.  

ERIC Educational Resources Information Center

This newsletter theme issue features articles on training of direct service staff working with persons with developmental disabilities in employment, education, and residential settings. The articles examine job training, delivery systems, training models, and implications of current approaches. The newsletter includes three articles presenting

Wallace, Teri, Ed.; And Others

1992-01-01

313

Zeolite modification II - direct fluorination  

Microsoft Academic Search

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

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

1982-01-01

314

Direct Sum Decomposition of Groups  

ERIC Educational Resources Information Center

|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

Thaheem, A. B.

2005-01-01

315

Directions to NCI-Frederick:  

Cancer.gov

Directions to NCI-Frederick: NCI-Frederick is located within the Fort Detrick U.S. Army facility in Frederick, Maryland. Please be aware that you will be asked to provide Fort Detrick security with two Government issued picture identifiers before

316

Direct Detection of Dark Matter  

NASA Astrophysics Data System (ADS)

The principles and some important features of the direct detection of dark matter are introduced, and recent experimental progress is reported. In particular, the XMASS experiment, which is a large-scale dark-matter experiment in Japan, is explained in detail.

Moriyama, S.

2012-08-01

317

Directional variations of apparent movement  

Microsoft Academic Search

Perceptions of the direction of apparent movement have been found to be characterized by wide individual differences under the conditions of stimulation used This diversity indicates the extreme complexity of the interaction of the basic determinants of these perceptions. Lack of knowledge of the physiological processes underlying perceptual activity makes it impossible to explain these changes in perception, except as

C. F. Willey

1936-01-01

318

Laboratory-Directed Protein Evolution  

PubMed Central

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.

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

2005-01-01

319

New Directions in Curriculum Study.  

ERIC Educational Resources Information Center

|In a discussion of new directions in curriculum study, alternatives to present patterns have been grouped under: (1) state and national studies, (2) articulation, (3) innovation in curriculum, (4) basic studies, (5) black studies, and (6) vocational education. A summary of major trends in curriculum development uses seven categories: (1) growth

Park, Young

1971-01-01

320

High Voltage Direct Current Transmission.  

National Technical Information Service (NTIS)

The report contains a brief summary of the technical status of high-voltage direct-current electric-power transmission in the United States and abroad. Since the first major d-c link from Stockholm to the island of Gotland began operation in 1954, at leas...

R. L. Shedden

1971-01-01

321

Broad-Band Directional Couplers  

Microsoft Academic Search

It is shown how to connect two identical hybrids to obtain a directional coupler of arbitrary power division that operates over a broader band than that of the components. The broad-banding technique is possible with a certain kind of hybrid that includes Riblet couplers, multihole hybrids, coaxial hybrids and semioptical hybrids, but excludes T hybrids and ring hybrids. Riblet couplers

E. A. Marcatili; D. H. Ring

1962-01-01

322

New Directions for Terrorism Research  

Microsoft Academic Search

We propose two new directions for terrorism research. One is to adopt a comparative framework, as we note that there was another wave of terrorism between 1878 and 1914 that strongly resembles todays 1968-present wave of international terrorism. The two should be compared, and at different levels of analysis from the individual terrorist incident through global spirals of terrorist waves.

Albert J. Bergesen; Yi Han

2005-01-01

323

Direct detection of dark matter axions with directional sensitivity  

NASA Astrophysics Data System (ADS)

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 ?a is sufficiently larger than the cavity dimensions L for a fully coherent conversion, i.e. ?agtrsim2?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.

Irastorza, Igor G.; Garca, Juan A.

2012-10-01

324

Sampling properties of directed networks  

NASA Astrophysics Data System (ADS)

For many real-world networks only a small sampled version of the original network may be investigated; those results are then used to draw conclusions about the actual system. Variants of breadth-first search (BFS) sampling, which are based on epidemic processes, are widely used. Although it is well established that BFS sampling fails, in most cases, to capture the IN component(s) of directed networks, a description of the effects of BFS sampling on other topological properties is all but absent from the literature. To systematically study the effects of sampling biases on directed networks, we compare BFS sampling to random sampling on complete large-scale directed networks. We present new results and a thorough analysis of the topological properties of seven complete directed networks (prior to sampling), including three versions of Wikipedia, three different sources of sampled World Wide Web data, and an Internet-based social network. We detail the differences that sampling method and coverage can make to the structural properties of sampled versions of these seven networks. Most notably, we find that sampling method and coverage affect both the bow-tie structure and the number and structure of strongly connected components in sampled networks. In addition, at a low sampling coverage (i.e., less than 40%), the values of average degree, variance of out-degree, degree autocorrelation, and link reciprocity are overestimated by 30% or more in BFS-sampled networks and only attain values within 10% of the corresponding values in the complete networks when sampling coverage is in excess of 65%. These results may cause us to rethink what we know about the structure, function, and evolution of real-world directed networks.

Son, S.-W.; Christensen, C.; Bizhani, G.; Foster, D. V.; Grassberger, P.; Paczuski, M.

2012-10-01

325

The Water Framework Directive and the Habitats and Birds Directives  

Microsoft Academic Search

\\u000a The Water Framework Directive not only describes a new method to classify and enhance the status of waters in the UK, it also\\u000a provides new obligations, a new management framework and additional monitoring requirements for water dependent Natura 2000\\u000a protected areas. Most importantly, it requires the achievement of any standards and objectives for these sites before 2015.\\u000a Whilst the ecological

Chris Uttley

326

Fault Branching and Rupture Directivity  

NASA Astrophysics Data System (ADS)

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.

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

2002-12-01

327

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

ERIC Educational Resources Information Center

|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

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

2012-01-01

328

Directional drilling azimuth control system  

SciTech Connect

A downhole anchor assembly is described for absorbing reaction torque from a downhole mud motor in a directional drill string so as to minimize azimuthal deviation from such reaction torque, the anchor assembly comprising: an elongated, generally cylindrical housing having upper and lower ends with tool joints thereon for coupling the body into a directional drill string and having a drilling fluid passage extending longitudinally through its length; at least one elongated chain support body longitudinally mounted in the housing; an elongated, endless anchor chain supported on the body, the chain having an elongated portion thereof longitudinally arranged and generally radially exposed externally of the body, the exposed chain portion being freely longitudinally movable along the body; the body being generally radially shiftable between a retracted position in which the exposed chain portion is substantially recessed in the housing; and actuating means in the housing engageable with the body for shifting the body from the retracted position to its extended position.

Cheek, A.E.

1986-09-23

329

Directed Evolution of Fungal Laccases  

PubMed Central

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.

Mate, Diana; Garcia-Ruiz, Eva; Camarero, Susana; Alcalde, Miguel

2011-01-01

330

GENE LOOPS ENHANCE TRANSCRIPTIONAL DIRECTIONALITY  

PubMed Central

Eukaryotic genomes are extensively transcribed, forming both messenger (m) and noncoding (nc) RNAs. ncRNAs made by RNA polymerase II (Pol II) often initiate from bidirectional promoters (nucleosome-depleted chromatin) that synthesise mRNA and ncRNA in opposite directions. We demonstrate that actively transcribed mRNA encoding genes by adopting a gene loop conformation, restrict divergent transcription of ncRNAs. Since gene loop formation depends on a protein factor (Ssu72) that co-associates with both promoter and terminator, its inactivation leads to increased synthesis of promoter-associated divergent ncRNAs, referred to as Ssu72 restricted transcripts (SRT). Similarly, inactivation of individual gene loops by gene mutation enhances SRT synthesis. We demonstrate that gene loop conformation enforces transcriptional directionality on otherwise bidirectional promoters.

Tan-Wong, Sue Mei; Zaugg, Judith B.; Camblong, Jurgi; Xu, Zhenyu; Zhang, David W.; Mischo, Hannah E.; Ansari, Aseem Z.; Luscombe, Nicholas M.; Steinmetz, Lars M.; Proudfoot, Nick J.

2012-01-01

331

ODE Direction Field Plotter Model  

NSDL National Science Digital Library

The Direction Field Plotter Model shows a graphical representation of the solutions to a first-order differential equation dx/dt=f(x,t) by plotting a grid of line segments with components that show the rate of change of the solution x(t) at each gridpoint. This slope field visualization uses normalized line segments to provide a qualitatively feel for the solution geometry. The solution curves can be sketched by connecting adjacent line segments. Clicking on an (x,t) point shows the exact solution starting at that point. The Direction Field Plotter Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Christian, Wolfgang; Franciscouembre

2012-08-21

332

Directional Compton profiles of silver  

NASA Astrophysics Data System (ADS)

The [100], [110], and [111] directional Compton profiles from Ag single crystals measured using 198Au (412 keV) and 137Cs (662 keV) sources, together with the corresponding theoretical profiles obtained within the charge self-consistent relativistic Korringa-Kohn-Rostoker band-structure methodology are presented. The overall amplitude and shape of the measured directional anisotropies are found to be in good accord with theoretical predictions based on the local-density approximation. In considering absolute Compton profiles, a substantial discrepancy between theory and experiment is found; however, this discrepancy is essentially removed by invoking an energy-independent correction to the data consistent with the presence of a significant bremsstrahlung background. The experimental and theoretical results are compared and contrasted with other relevant available data in the literature.

Andrejczuk, A.; Dobrzy?ski, L.; Kwiatkowska, J.; Maniawski, F.; Kaprzyk, S.; Bansil, A.; ?ukowski, E.; Cooper, M. J.

1993-12-01

333

6Li direct breakup lifetimes  

NASA Astrophysics Data System (ADS)

?-d coincidence data are studied for the 6Li + 59Co reaction at E=29.6 MeV. A kinematic analysis is used to identify which process, leading to the same final state, has the major contribution for selected angular regions. The contributions of the 6Li sequential and direct breakup to the incomplete fusion/transfer process is discussed by considering the corresponding lifetimes obtained by using a semiclassical approach.

Souza, F. A.; Carlin, N.; Beck, C.; Keeley, N.; Diaz-Torres, A.; Liguori Neto, R.; Siqueira-Mello, C.; de Moura, M. M.; Munhoz, M. G.; Oliveira, R. A. N.; Del Santo, M. G.; Suaide, A. A. P.; Szanto, E. M.; Szanto de Toledo, A.

2010-03-01

334

Future directions in desktop video  

Microsoft Academic Search

Good morning. My name is Tim Heidmann and I'd like to welcomeyou all to this panel, which is entitled Future Directions inDesktop Video, and I'd especially like to thank all you people whostayed up a little late on Thursday night to come to this panel.It's really good to see you all out there.I've gotten word that this panel is being

T. Heidmnn; M. MacKay; G. MacNicol; F. Wray

1989-01-01

335

Direct firing downhole steam generator  

SciTech Connect

A direct firing down-hole steam generator is composed of an injector assembly axially connected with a combustion chamber. Downstream of the combustion chamber and oriented so as to receive its output is a heat exchanger where preheated water is injected into the heat exchanger through a number of one-way valves. The heated water is vaporized and injected through a nozzle, packer, and check valve into the well formation. 9 claims.

Wagner, W.R.; Wright, D.E.; Binsley, R.L.

1982-06-29

336

AUTOMATIC AIR BURST DIRECTION FINDER  

DOEpatents

This patent application describes an atomic explosion direction indicator comprising a geometric heat-scorchable indicating surface symmetrical about an axis, elevation and azimuth markings on the heat scorchable surface, and an indicating rod at the axis of said surface arranged to cast a shadow hereon, whereby heat from an atomic explosion will scorch a pattern on said surface indicative of the azimuth and elevation of said explosion.

Allard, G.A.

1952-01-31

337

Anticipatory, Goal-Directed Behavior  

Microsoft Academic Search

David Hume may be one of the first who thought about the causes that actually enable us to act goal-directedly in our pursuit\\u000a of happiness. Besides having usually an end, or goal, in mind, Hume realized that the end must elicit those means that were\\u000a learned to correlate with the end. Such correlation knowledge, according to Hume (1748), was based

Martin V. Butz; Oliver Herbort; Giovanni Pezzulo

2008-01-01

338

Relativistic propulsion using directed energy  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

339

Direct search for dark matter  

SciTech Connect

Dark matter is hypothetical matter which does not interact with electromagnetic radiation. The existence of dark matter is only inferred from gravitational effects of astrophysical observations to explain the missing mass component of the Universe. Weakly Interacting Massive Particles are currently the most popular candidate to explain the missing mass component. I review the current status of experimental searches of dark matter through direct detection using terrestrial detectors.

Yoo, Jonghee; /Fermilab

2009-12-01

340

Direct numerical simulations of turbulence  

Microsoft Academic Search

Due to exceptional possibilities offered by large scientific calculators, the direct, unstationary resolution of Navier-Stokes equations in situations pertaining to turbulence and transition is now at hand. In this paper, we develop very high resolution simulations of three-dimensional incompressible and compressible mixing layers, developed isotropic turbulence, and rotating turbulence. We focus on coherent structures and large-scale intermittency. In the mixing-layer

M. Lesieur; P. Comte; O. Metals

1992-01-01

341

BNL Direct Wind Superconducting Magnets  

SciTech Connect

BNL developed Direct Wind magnet technology is used to create a variety of complex multi-functional multi-layer superconducting coil structures without the need for creating custom production tooling and fixturing for each new project. Our Direct Wind process naturally integrates prestress into the coil structure so external coil collars and yokes are not needed; the final coil package transverse size can then be very compact. Direct Wind magnets are produced with very good field quality via corrections applied during the course of coil winding. The HERA-II and BEPC-II Interaction Region (IR) magnet, J-PARC corrector and Alpha antihydrogen magnetic trap magnets and our BTeV corrector magnet design are discussed here along with a full length ILC IR prototype magnet presently in production and the coils that were wound for an ATF2 upgrade at KEK. A new IR septum magnet design concept for a 6.2 T combined-function IR magnet for eRHIC, a future RHIC upgrade, is introduced here.

Parker, B.; Anerella, M.; Escallier, J.; Ghosh, A.; Jain, A.; Marone, A.; Muratore, A.; Wanderer, P.

2011-09-12

342

Direct reciprocity in structured populations  

PubMed Central

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.

van Veelen, Matthijs; Garcia, Julian; Rand, David G.; Nowak, Martin A.

2012-01-01

343

Wellbore inertial directional surveying system  

SciTech Connect

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.

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

1991-01-29

344

Optimized Direct-Drive Uniformity  

NASA Astrophysics Data System (ADS)

The means of optimizing direct-drive illumination uniformity in laser fusion implosions will be discussed. To provide the most-uniform drive, the target must be illuminated by smooth single beams, symmetrically placed on target, with the optimum beam shape. On the 60-beam OMEGA laser system these near-optimum, direct-drive illumination conditions have been achieved by smoothing each beam with 1-THz smoothing by spectral dispersion (SSD), which incorporates distributed phase plates (DPP's) and polarization smoothing (PS), and by the modified soccer-ball orientation of the beams. The current beam smoothing provides for unprecedented levels of direct-drive uniformity, approaching ?_rms 2% up to ? = 200 after 300 ps. The sensitivity of the illumination to beam shape has been studied, and a new set of DPP's have been designed and are being built to further optimize the uniformity on OMEGA. Also, the sensitivity of the drive to beam balance, beam pointing, and target positioning has been studied both by calculation and by performing target implosions allowing quantitative limits to be placed on all contributors. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

Marshall, F. J.; McKenty, P. W.; Kessler, T. J.; Forties, R.; Kelly, J. A.; Waxer, L. J.

2002-11-01

345

Direct execution of LISP on a list-directed architecture  

SciTech Connect

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.

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

1982-03-01

346

42 CFR 431.20 - Advance directives.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false Advance directives. 431.20 ...HUMAN SERVICES (CONTINUED) MEDICAL ASSISTANCE PROGRAMS STATE...State Agency § 431.20 Advance directives. (a) Basis...description of State law concerning advance directives. (b)...

2012-10-01

347

Human Ears Inspired Passive Microwave Direction Finding.  

National Technical Information Service (NTIS)

We have investigated biological inspired RF direction finding techniques with the goal to learn and utilize the amazing acoustic direction finding capabilities of human and achieve compact, high performance and low- cost RF direction finding devices. Our ...

H. Xin

2009-01-01

348

Extremely High Frequency Directly Modulated Lasers.  

National Technical Information Service (NTIS)

Several novel directly modulated semiconductor laser structures have been investigated to increase the bandwidth of direct modulation. Detailed theoretical models were developed and a high speed directly modulated laser was fabricated and tested. Corner r...

R. Spencer J. Greenberg L. Eastman

1997-01-01

349

A metamaterial for directive emission.  

PubMed

In this paper we present the first results on emission in metamaterial. We show how the specific properties of metallic composite material can modify the emission of an embedded source. We show that under proper conditions the energy radiated by a source embedded in a slab of metamaterial will be concentrated in a narrow cone in the surrounding media. An experimental demonstration of this effect is given in the microwave domain, and the constructed antenna has a directivity equivalent to the best reported results with photonic-crystal-based antennas but using a completely different physical principle [B. Temelkuaran, J. Appl. Phys. 87, 603 (2000)

Enoch, Stefan; Tayeb, Grard; Sabouroux, Pierre; Gurin, Nicolas; Vincent, Patrick

2002-11-04

350

Nerve lesioning with direct current  

NASA Astrophysics Data System (ADS)

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.

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

2011-02-01

351

Direct CP violation at LHCb  

NASA Astrophysics Data System (ADS)

During 2011, LHCb has collected an integrated luminosity of 1.0fb giving rise to a large variety of measurements. Among these, measurements of direct CP violation in B decays play a central role. Three different analyses are presented: the first evidence of CP violation in the Bs0 system and the observation of CP violation in the B0 system, using B0?K? and Bs0??K decay channels; the evidence of CP violation in B?DK decays with the first observation of the suppressed ADS mode; and a preliminary result showing the evidence of CP asymmetry in charmless three-body charged B decays.

LHCb Collaboration; Cardinale, R.

2012-12-01

352

Future Directions for Soft Computing  

Microsoft Academic Search

\\u000a In this paper we discuss possible future directions of research for soft computing in the context of artificial intelligence\\u000a and knowledge engineering. Fundamental issues are presented with basic ideas emphasised rather than detailed accounts of algorithms\\u000a and procedures.\\u000a \\u000a \\u000a The use of fuzzy sets to machine learning, computer intelligence and creativity are discussed in relation to the central problems\\u000a of creating

James F. Baldwin

2000-01-01

353

Direct application of geothermal energy  

SciTech Connect

An overall treatment of direct geothermal applications is presented with an emphasis on the above-ground engineering. The types of geothermal resources and their general extent in the US are described. The potential market that may be served with geothermal energy is considered briefly. The evaluation considerations, special design aspects, and application approaches for geothermal energy use in each of the applications are considered. The present applications in the US are summarized and a bibliography of recent studies and applications is provided. (MHR)

Reistad, G.M.

1980-01-01

354

Direct Arthroscopic Distal Clavicle Resection  

PubMed Central

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.

Lervick, Gregory N

2005-01-01

355

Surface passivation optimization using DIRECT  

SciTech Connect

We describe a systematic and efficient method of determining pseudo-atom positions and potentials for use in nanostructure calculations based on bulk empirical pseudopotentials (EPMs). Given a bulk EPM for binary semiconductor X, we produce parameters for pseudo-atoms necessary to passivate a nanostructure of X in preparation for quantum mechanical electronic structure calculations. These passivants are based on the quality of the wave functions of a set of small test structures that include the passivants. Our method is based on the global optimization method DIRECT. It enables and/or streamlines surface passivation for empirical pseudopotential calculations.

Graf, Peter A. [National Renewable Energy Laboratory (NREL), Golden, CO 80401 (United States)]. E-mail: peter_graf@nrel.gov; Kim, Kwiseon [National Renewable Energy Laboratory (NREL), Golden, CO 80401 (United States); Jones, Wesley B. [National Renewable Energy Laboratory (NREL), Golden, CO 80401 (United States); Wang, Lin-Wang [Computational Research Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA 94720 (United States)

2007-06-10

356

Direct Reactions of Borromean Nuclei  

SciTech Connect

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.

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

2008-04-29

357

Direct electrochemical oxidation of polyacrylates.  

PubMed

A promising elimination treatment of non-biodegradable organic pollutants is the direct electro-oxidation. In this work has been proposed the electrochemical elimination of polyacrylates by using boron-doped diamond (BDD) as anodic material. The complete elimination of organic contaminants has been obtained and this is the first case of successful electrochemical treatment of polymeric and bio-refractory species. The tests of the electrochemical oxidation have been conducted at constant current conditions and a complete elimination of organic species has been reached. The decrease of the COD value with time follows the behaviour of an ideal anode as in the case of low molecular organic compounds. PMID:12489259

Bellagamba, Riccardo; Comninellis, Christos; Vatistas, Nicolaos

2002-10-01

358

Direct measure of quantum correlation  

SciTech Connect

The quantumness of the correlation known as quantum correlation is usually measured by quantum discord. So far various quantum discords can be roughly understood as indirect measure by some special discrepancy of two quantities. We present a direct measure of quantum correlation by revealing the difference between the structures of classically and quantum correlated states. Our measure explicitly includes the contributions of the inseparability and local nonorthogonality of the eigenvectors of a density matrix. Besides its relatively easy computability, our measure can provide a unified understanding of quantum correlation of all the present versions.

Yu, Chang-shui [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Zhao, Haiqing [School of Science, Dalian Jiaotong University, Dalian 116028 (China)

2011-12-15

359

Transcutaneous spinal direct current stimulation.  

PubMed

In the past 10?years renewed interest has centered on non-invasive transcutaneous weak direct currents applied over the scalp to modulate cortical excitability ("brain polarization" or transcranial direct current stimulation, tDCS). Extensive literature shows that tDCS induces marked changes in cortical excitability that outlast stimulation. Aiming at developing a new, non-invasive, approach to spinal cord neuromodulation we assessed the after-effects of thoracic transcutaneous spinal DC stimulation (tsDCS) on somatosensory potentials (SEPs) evoked in healthy subjects by posterior tibial nerve (PTN) stimulation. Our findings showed that thoracic anodal tsDCS depresses the cervico-medullary PTN-SEP component (P30) without eliciting adverse effects. tsDCS also modulates post-activation H-reflex dynamics. Later works further confirmed that transcutaneous electric fields modulate spinal cord function. Subsequent studies in our laboratory showed that tsDCS modulates the flexion reflex in the human lower limb. Besides influencing the laser evoked potentials (LEPs), tsDCS increases pain tolerance in healthy subjects. Hence, though the underlying mechanisms remain speculative, tsDCS modulates activity in lemniscal, spinothalamic, and segmental motor systems. Here we review currently available experimental evidence that non-invasive spinal cord stimulation (SCS) influences spinal function in humans and argue that, by focally modulating spinal excitability, tsDCS could provide a novel therapeutic tool complementary to drugs and invasive SCS in managing various pathologic conditions, including pain. PMID:22783208

Cogiamanian, Filippo; Ardolino, Gianluca; Vergari, Maurizio; Ferrucci, Roberta; Ciocca, Matteo; Scelzo, Emma; Barbieri, Sergio; Priori, Alberto

2012-07-04

360

Direct Current Electrical Motor Model  

NSDL National Science Digital Library

The Direct Current Electrical Motor Model illustrates a simple direct current (DC) motor. The model shows an external magnet (called the stator because its fixed in place) and a turning coil of wire called an armature ( rotor or coil, because it rotates). The armature, carrying current provided by the battery, is an electromagnet, because a current-carrying wire generates a magnetic field; invisible magnetic field lines are circulating all around the wire of the armature. The key to producing motion is positioning the electromagnet within the magnetic field of the permanent magnet (its field runs from its north to south poles). The armature experiences a force described by the left hand rule. This interplay of magnetic fields and moving charged particles (the electrons in the current) results in the magnetic force (depicted by the green arrows) that makes the armature spin because of the torque. Use the slider current I to see what happens when the flow of current is reversed. The checkbox current flow & electron flow alows different visualization since I = d(Q)/dt and Q= number of charge*e. The Play & Pause button allows freezing the 3D view for visualizing these forces, for checking for consistency with the left hand rule .

Hwang, Fu-Kwun; Wee, Loo K.

2011-11-23

361

Direct detection polarimetric radiometer (DDPR)  

NASA Astrophysics Data System (ADS)

Polarimetric signatures of terrain features and man-made objects have been measured using unique Direct Detection Polarimetric Radiometers (DDPR). The DDPRs are lightweight inexpensive systems operating at 35 and 94 GHz. Each system consists of a single antenna, amplifier, and a truncated cylindrical waveguide that directly measures Q, U, and V. The highly portable DDPRs are ideal for obtaining the Stokes vectors needed to study the physical characteristics of natural and man-made features. Field evaluations using the DDPR systems include measurements from an airborne platform over different terrain features and water, and ground based measurements of the polarimetric signature of grass, asphalt, buildings, and concealed munitions. The DDPR can function as a bistatic system by using an active source of polarization. Using this configuration and a soil chamber, we have investigated the effect of soil type and soil moisture on linear and circular polarization. This report will describe the DDPR and present the analysis of the airborne and ground based measurements, including the effects of soil type and soil moisture on sources of linear and circular polarization.

Koenig, G.; Koh, G.; Ryerson, C.

2009-05-01

362

Semantics of directly manipulating spatializations.  

PubMed

When high-dimensional data is visualized in a 2D plane by using parametric projection algorithms, users may wish to manipulate the layout of the data points to better reflect their domain knowledge or to explore alternative structures. However, few users are well-versed in the algorithms behind the visualizations, making parameter tweaking more of a guessing game than a series of decisive interactions. Translating user interactions into algorithmic input is a key component of Visual to Parametric Interaction (V2PI) [13]. Instead of adjusting parameters, users directly move data points on the screen, which then updates the underlying statistical model. However, we have found that some data points that are not moved by the user are just as important in the interactions as the data points that are moved. Users frequently move some data points with respect to some other 'unmoved' data points that they consider as spatially contextual. However, in current V2PI interactions, these points are not explicitly identified when directly manipulating the moved points. We design a richer set of interactions that makes this context more explicit, and a new algorithm and sophisticated weighting scheme that incorporates the importance of these unmoved data points into V2PI. PMID:24051771

Hu, Xinran; Bradel, Lauren; Maiti, Dipayan; House, Leanna; North, Chris; Leman, Scotland

2013-12-01

363

Current Developments in Self-Directed Learning.  

ERIC Educational Resources Information Center

This document contains the following papers examining current developments in self-directed learning: "Self-Directed Learning: Challenges and Opportunities" (Huey B. Long); "Examination of Self-Directed Learning Readiness and Selected Demographic Variables of Top Female Executives" (Lucy M. Guglielmino); "Enhancing Self-Directed Learning in the

Long, Huey B.; And Others

364

Novel broadband multilayer microstrip directional couplers  

Microsoft Academic Search

Design method of novel multilayer, broadband six port microstrip directional coupler at VHF- UHF range for high power applications is given. Directional coupler is modeled and simulated with the method of moments based planar electromagnetic simulator on a two-layer Alumina substrate. It is shown that the high directivity and desired coupling level of the directional coupler are maintained within 300MHz

Abdullah Eroglu; Richard Goulding; Phil Ryan; John Caughman; David Rasmussen

2010-01-01

365

Theory of directional pulse propagation  

NASA Astrophysics Data System (ADS)

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 Maxwells 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.

Kinsler, P.; Radnor, S. B. P.; New, G. H. C.

2005-12-01

366

Method for directional hydraulic fracturing  

DOEpatents

A method for directional hydraulic fracturing using borehole seals to confine pressurized fluid in planar permeable regions, comprising: placing a sealant in the hole of a structure selected from geologic or cemented formations to fill the space between a permeable planar component and the geologic or cemented formation in the vicinity of the permeable planar component; making a hydraulic connection between the permeable planar component and a pump; permitting the sealant to cure and thereby provide both mechanical and hydraulic confinement to the permeable planar component; and pumping a fluid from the pump into the permeable planar component to internally pressurize the permeable planar component to initiate a fracture in the formation, the fracture being disposed in the same orientation as the permeable planar component.

Swanson, David E. (West St. Paul, MN); Daly, Daniel W. (Crystal, MN)

1994-01-01

367

Theory of directional pulse propagation  

SciTech Connect

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.

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

368

Direct measurement of turbulent shear  

NASA Astrophysics Data System (ADS)

A photon correlation method is introduced for measuring components of the shear rate tensor in a turbulent soap film. This new scheme, which is also applicable to three-dimensional flows, is shown to give the same results as laser Doppler velocimetry, but with less statistical noise. The technique yields the mean shear rate s, its standard deviation ?, and a simple mathematical transform of the probability density function P(s) of the shear rate itself. We propose a new method that can directly measure shear in 2 dimensional turbulence. This proposed method has better signal to noise ratio than the conventional method. It also yields information about the probability distribution of shear. The proposed method is inexpensive and applicable to 3 dimensional turbulence.

Stefanus, S.; Steers, S.; Goldburg, W. I.

2011-11-01

369

Direct reconstruction of dark energy.  

PubMed

An important issue in cosmology is reconstructing the effective dark energy equation of state directly from observations. With so few physically motivated models, future dark energy studies cannot only be based on constraining a dark energy parameter space. We present a new nonparametric method which can accurately reconstruct a wide variety of dark energy behavior with no prior assumptions about it. It is simple, quick and relatively accurate, and involves no expensive explorations of parameter space. The technique uses principal component analysis and a combination of information criteria to identify real features in the data, and tailors the fitting functions to pick up trends and smooth over noise. We find that we can constrain a large variety of w(z) models to within 10%-20% at redshifts z?1 using just SNAP-quality data. PMID:20867085

Clarkson, Chris; Zunckel, Caroline

2010-05-27

370

Direct phasing of nanocrystal diffraction.  

PubMed

Recent experiments at free-electron laser X-ray sources have been able to resolve the intensity distributions about Bragg peaks in nanocrystals of large biomolecules. Information derived from small shifts in the peak positions augment the Bragg samples of the particle intensity with samples of its gradients. Working on the assumption that the nanocrystal is entirely generated by lattice translations of a particle, an algorithm is developed that reconstructs the particle from intensities and intensity gradients. Unlike traditional direct phasing methods that require very high resolution data in order to exploit sparsity of the electron density, this method imposes no constraints on the contrast other than positivity and works well at low resolution. Successful reconstructions are demonstrated with simulated P1 lysozyme nanocrystal data down to a signal-to-noise ratio of 2 in the intensity gradients. PMID:24132217

Elser, Veit

2013-10-05

371

Directed Therapy for Exfoliation Syndrome  

PubMed Central

Exfoliation syndrome (XFS) is an age-related disorder of the extracellular matrix that leads the production of abnormal fibrillar material that leads to elevated intraocular pressure and a relatively severe glaucoma. Exfoliation material is deposited in numerous ocular tissues and extraocular organs. XFS is associated with ocular ischemia, cerebrovascular disease, neurodegenerative disease and cardiovascular disease. Current modalities of treatment include intraocular pressure lowering with topical antihypertensives, laser trabeculoplasty and filtration surgery. The disease paradigm for XFS should be expanded to include directed therapy designed specifically to target the underlying disease process. Potential targets include preventing the formation or promoting the depolymerization of exfoliation material. Novel therapies targeting trabecular meshwork may prove particularly useful in the care of exfoliative glaucoma. The systemic and ocular associations of XFS underscore the need for a comprehensive search for neuroprotective agents in its treatment.

Angelilli, Allison; Ritch, Robert

2009-01-01

372

Direct synthesis of calcium borohydride  

DOEpatents

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.

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

2009-10-27

373

Saccharomyces cerevisiae in directed evolution  

PubMed Central

Over the past 20 years, directed evolution has been seen to be the most reliable approach to protein engineering. Emulating the natural selection algorithm, ad hoc enzymes with novel features can be tailor-made for practical purposes through iterative rounds of random mutagenesis, DNA recombination and screening. Of the heterologous hosts used in laboratory evolution experiments, the budding yeast Saccharomyces cerevisiae has become the best choice to express eukaryotic proteins with improved properties. S. cerevisiae not only allows mutant enzymes to be secreted but also, it permits a wide range of genetic manipulations to be employed, ranging from in vivo cloning to the creation of greater molecular diversity, thanks to its efficient DNA recombination apparatus. Here, we summarize some successful examples of the use of the S. cerevisiae machinery to accelerate artificial evolution, complementing the traditional in vitro methods to generate tailor-made enzymes.

Gonzalez-Perez, David; Garcia-Ruiz, Eva; Alcalde, Miguel

2012-01-01

374

Laboratory directed research and development  

SciTech Connect

The purposes of Argonne's Laboratory Directed Research and Development (LDRD) Program are to encourage the development of novel concepts, enhance the Laboratory's R D capabilities, and further the development of its strategic initiatives. Among the aims of the projects supported by the Program are establishment of engineering proof-of-principle''; development of an instrumental prototype, method, or system; or discovery in fundamental science. Several of these project are closely associated with major strategic thrusts of the Laboratory as described in Argonne's Five Year Institutional Plan, although the scientific implications of the achieved results extend well beyond Laboratory plans and objectives. The projects supported by the Program are distributed across the major programmatic areas at Argonne. Areas of emphasis are (1) advanced accelerator and detector technology, (2) x-ray techniques in biological and physical sciences, (3) advanced reactor technology, (4) materials science, computational science, biological sciences and environmental sciences. Individual reports summarizing the purpose, approach, and results of projects are presented.

Not Available

1991-11-15

375

Future directions in cancer prevention.  

PubMed

Prevention of cancer remains the most promising strategy for reducing both its incidence and the mortality due to this disease. For more than four decades, findings from epidemiology, basic research and clinical trials have informed the development of lifestyle and medical approaches to cancer prevention. These include selective oestrogen receptor modulators and aromatase inhibitors for breast cancer, the 5-?-reductase inhibitors finasteride and dutasteride for prostate cancer, and the development of vaccines for viruses that are associated with specific cancers. Future directions include genetic, proteomic and other molecular approaches for identifying pathways that are associated with cancer initiation and development, as well as refining the search for immunologically modifiable causes of cancer. PMID:23151603

Umar, Asad; Dunn, Barbara K; Greenwald, Peter

2012-11-15

376

Direct synthesis of magnesium borohydride  

DOEpatents

A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Mg(BH.sub.4).sub.2, from the alkaline earth metal boride MgB.sub.2 by hydrogenating the MgB.sub.2 at an elevated temperature and pressure. The boride may also be doped with small amounts of a metal chloride catalyst such as TiCl.sub.3 and/or NiCl.sub.2. The process provides for charging MgB.sub.2 with high pressure hydrogen above at least 70 MPa while simultaneously heating the material to about 350.degree. C. to about 400.degree. C. The method is relatively simple and inexpensive and provides a reversible hydride compound having a hydrogen capacity of at least 11 wt %.

Ronnebro, Ewa Carin Ellinor (Kennewick, WA); Severa, Godwin (Honolulu, HI); Jensen, Craig M. (Kailua, HI)

2012-04-03

377

Optimal pinning synchronization on directed complex network  

NASA Astrophysics Data System (ADS)

In this paper, pinning synchronization on directed network was considered. By analyzing, some general synchronization criteria on directed network were established. And then, we verified it on directed globally coupled network, directed scale-free network, and directed small-world network, respectively. The pinning nodes were selected, respectively, according to order of in-degrees and out-degrees. Through comparing and analyzing simulations, the optimal pinning scheme was found, and a practical principle was induced finally.

Nian, Fuzhong; Wang, Xingyuan

2011-12-01

378

Modeling the directivity of parametric loudspeaker  

NASA Astrophysics Data System (ADS)

The emerging applications of the parametric loudspeaker, such as 3D audio, demands accurate directivity control at the audible frequency (i.e. the difference frequency). Though the delay-and-sum beamforming has been proven adequate to adjust the steering angles of the parametric loudspeaker, accurate prediction of the mainlobe and sidelobes remains a challenging problem. It is mainly because of the approximations that are used to derive the directivity of the difference frequency from the directivity of the primary frequency, and the mismatches between the theoretical directivity and the measured directivity caused by system errors incurred at different stages of the implementation. In this paper, we propose a directivity model of the parametric loudspeaker. The directivity model consists of two tuning vectors corresponding to the spacing error and the weight error for the primary frequency. The directivity model adopts a modified form of the product directivity principle for the difference frequency to further improve the modeling accuracy.

Shi, Chuang; Gan, Woon-Seng

2012-09-01

379

Direct detector for terahertz radiation  

DOEpatents

A direct detector for terahertz radiation comprises a grating-gated field-effect transistor with one or more quantum wells that provide a two-dimensional electron gas in the channel region. The grating gate can be a split-grating gate having at least one finger that can be individually biased. Biasing an individual finger of the split-grating gate to near pinch-off greatly increases the detector's resonant response magnitude over prior QW FET detectors while maintaining frequency selectivity. The split-grating-gated QW FET shows a tunable resonant plasmon response to FIR radiation that makes possible an electrically sweepable spectrometer-on-a-chip with no moving mechanical optical parts. Further, the narrow spectral response and signal-to-noise are adequate for use of the split-grating-gated QW FET in a passive, multispectral terahertz imaging system. The detector can be operated in a photoconductive or a photovoltaic mode. Other embodiments include uniform front and back gates to independently vary the carrier densities in the channel region, a thinned substrate to increase bolometric responsivity, and a resistive shunt to connect the fingers of the grating gate in parallel and provide a uniform gate-channel voltage along the length of the channel to increase the responsivity and improve the spectral resolution.

Wanke, Michael C. (Albuquerque, NM); Lee, Mark (Albuquerque, NM); Shaner, Eric A. (Albuquerque, NM); Allen, S. James (Santa Barbara, CA)

2008-09-02

380

Direct charged particle imaging sensors  

NASA Astrophysics Data System (ADS)

CMOS image sensors optimized for charged particle imaging applications, such as electron microscopy and particle physics, have been designed and characterized. These directly image charged particles without reliance on performance-degrading hybrid technologies such as the use of scintillating materials. Based on standard CMOS active pixel sensor (APS) technology, the sensor arrays uses an 8 20 ?m epitaxial layer that acts as a thicker sensitive region for the generation and collection of ionization electrons resulting from impinging high-energy particles. This results in a 100% fill factor and a far larger signal per incident electron than a standard CMOS photodiode could provide. A 512550 pixels prototype has been fabricated and used extensively in an electron microscope, including having been used to take sample images. Temporal noise was measured to be 0.9 mV RMS, and the dynamic range was 60 dB. Power consumption at 70 frames/s is 20 mW. The full-width half-maximum of the collected ionization electron distribution was found to be 5.5 ?m, yielding a spatial resolution of approximately 2.3 ?m for individual incident electrons, and the modulation transfer function of the sensor at the Nyquist limit is to be 32%.

Li, Shengdong; Kleinfelder, Stuart

2007-08-01

381

Future directions of electron crystallography.  

PubMed

In biological science, there are still many interesting and fundamental yet difficult questions, such as those in neuroscience, remaining to be answered. Structural and functional studies of membrane proteins, which are key molecules of signal transduction in neural and other cells, are essential for understanding the molecular mechanisms of many fundamental biological processes. Technological and instrumental advancements of electron microscopy have facilitated comprehension of structural studies of biological components, such as membrane proteins. While X-ray crystallography has been the main method of structure analysis of proteins including membrane proteins, electron crystallography is now an established technique to analyze structures of membrane proteins in the lipid bilayer, which is close to their natural biological environment. By utilizing cryo-electron microscopes with helium-cooled specimen stages, structures of membrane proteins were analyzed at a resolution better than 3 . Such high-resolution structural analysis of membrane proteins by electron crystallography opens up the new research field of structural physiology. Considering the fact that the structures of integral membrane proteins in their native membrane environment without artifacts from crystal contacts are critical in understanding their physiological functions, electron crystallography will continue to be an important technology for structural analysis. In this chapter, I will present several examples to highlight important advantages and to suggest future directions of this technique. PMID:23132081

Fujiyoshi, Yoshinori

2013-01-01

382

Modern Directions for Potentiometric Sensors.  

PubMed

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

Bakker, Eric; Chumbimuni-Torres, Karin

2008-01-01

383

Direct Fast-Neutron Detection  

SciTech Connect

Direct fast-neutron detection is the detection of fast neutrons before they are moderated to thermal energy. We have investigated two approaches for using proton-recoil in plastic scintillators to detect fast neutrons and distinguish them from gamma-ray interactions. Both approaches use the difference in travel speed between neutrons and gamma rays as the basis for separating the types of events. In the first method, we examined the pulses generated during scattering in a plastic scintillator to see if they provide a means for distinguishing fast-neutron events from gamma-ray events. The slower speed of neutrons compared to gamma rays results in the production of broader pulses when neutrons scatter several times within a plastic scintillator. In contrast, gamma-ray interactions should produce narrow pulses, even if multiple scattering takes place, because the time between successive scattering is small. Experiments using a fast scintillator confirmed the presence of broader pulses from neutrons than from gamma rays. However, the difference in pulse widths between neutrons and gamma rays using the best commercially available scintillators was not sufficiently large to provide a practical means for distinguishing fast neutrons and gamma rays on a pulse-by-pulse basis. A faster scintillator is needed, and that scintillator might become available in the future. Results of the pulse-width studies were presented in a previous report (Peurrung et al. 1998), and they are only summarized here.

Stromswold, David C.; Peurrung, Anthony J.; Hansen, Randy R.; Reeder, Paul L.

1999-12-30

384

Low backlash direct drive actuator  

DOEpatents

A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw. 10 figs.

Kuklo, T.C.

1994-10-25

385

Low backlash direct drive actuator  

DOEpatents

A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw.

Kuklo, Thomas C. (Oakland, CA)

1994-01-01

386

Tocolysis: current controversies, future directions.  

PubMed

The use of tocolytic agents for the treatment of preterm labor is not supported by the current evidence from placebo-controlled trials. Despite this, tocolytics continue to be widely used in clinical practice. Possible reasons for the lack of observed benefit include the hypothesis that suppression of labor may be harmful in some situations, along with a failure to appreciate the implications of the complex physiology of parturition. Importantly, however, it must be recognized that the quality of evidence addressing the question is poor, with studies significantly underpowered to detect changes in health outcomes. Where tocolysis is used, recent trends have favored agents with lower maternal side effect profiles, including calcium channel blockers and the oxytocin receptor antagonist atosiban. The use of cyclooxygenase-selective inhibitors of prostaglandin synthesis is currently being explored. Future directions in tocolytic research include the use of multiple agent therapies, along with the development of more selective treatments with low side effect profiles. Such agents include oxytocin receptor antagonists with more favorable pharmacological properties and prostaglandin F2alpha receptor antagonists. Future research into tocolytic therapies must focus on evaluating health outcomes from treatments rather than simply the ability to prolong pregnancy, and consequently the design of appropriate clinical studies needs careful consideration with respect to issues such as inclusion criteria, sample size and the selection of appropriate outcome measures. PMID:15134284

Cole, Stephen; Smith, Roger; Giles, Warwick

2004-04-01

387

Interface Reconstruction with Directional Walking  

SciTech Connect

Young's interface reconstruction with three-dimensional arbitrary mesh, in general, is rather tedious to implement compared to the case of a regular mesh. The main difficulty comes from the construction of a planar facet that bounds a certain volume inside a cell. Unlike the five basic configurations with a Cartesian mesh, there can be a great number of different configurations in the case of a general mesh. We represent a simple method that can derive the topology/geometry of the intersection of arbitrary planar objects in a uniform way. The method is based on a directional walking on the surface of objects, and links the intersection points with the paths of the walking naturally defining the intersection of objects. The method works in both two and three dimensions. The method does not take advantage of convexity, thus decomposition of an object is not necessary. Therefore, the solution with this method will have a reduced number of edges and less data storage, compared with methods that use shape decomposition. The treatment is general for arbitrary polyhedrons, and no look-up tables are needed. The same operation can easily be extended for curved geometry. The implementation of this new algorithm shall allow the interface reconstruction on an arbitrary mesh to be as simple as it is on a regular mesh. Furthermore, we exactly compute the integral of partial cell volume bounded by quadratic interface. Therefore, interface reconstruction with higher than second order accuracy can be achieved on an arbitrary mesh.

Yao, J

2009-05-22

388

Direct gene transfer to plants  

PubMed Central

Evidence for direct, gene-mediated stable genetic transformation of plant cells of Nicotiana tabacum is presented. A selectable hybrid gene comprising the protein coding region of the Tn5 aminoglycoside phosphotransferase type II gene under control of cauliflower mosaic virus gene VI expression signals was introduced into plant protoplasts as part of an Escherichia coli plasmid. The gene was stably integrated into plant genomic DNA and constitutively expressed in selected, drug resistant, protoplast-derived cell clones. The mode of integration of the foreign gene into the plant genome resembled that observed for DNA transfection of mammalian cells. Plants regenerated from transformed cell lines were phenotypically normal and fertile, and they maintained and expressed the foreign gene throughout the development of vegetative and generative organs. Microspores, grown in anther culture, developed into resistant and sensitive haploid plantlets. Genetic crossing analysis of one of the transformed plants revealed the presence of one dominant trait for kanamycin resistance segregating in a Mendelian fashion in the F1 generation. ImagesFig. 2.Fig. 3.Fig. 4.Fig. 5.Fig. 6.

Paszkowski, Jerzy; Shillito, Raymond D.; Saul, Michael; Mandak, Vaclav; Hohn, Thomas; Hohn, Barbara; Potrykus, Ingo

1984-01-01

389

Direct gene transfer to plants.  

PubMed

Evidence for direct, gene-mediated stable genetic transformation of plant cells of Nicotiana tabacum is presented. A selectable hybrid gene comprising the protein coding region of the Tn5 aminoglycoside phosphotransferase type II gene under control of cauliflower mosaic virus gene VI expression signals was introduced into plant protoplasts as part of an Escherichia coli plasmid. The gene was stably integrated into plant genomic DNA and constitutively expressed in selected, drug resistant, protoplast-derived cell clones. The mode of integration of the foreign gene into the plant genome resembled that observed for DNA transfection of mammalian cells. Plants regenerated from transformed cell lines were phenotypically normal and fertile, and they maintained and expressed the foreign gene throughout the development of vegetative and generative organs. Microspores, grown in anther culture, developed into resistant and sensitive haploid plantlets. Genetic crossing analysis of one of the transformed plants revealed the presence of one dominant trait for kanamycin resistance segregating in a Mendelian fashion in the F(1) generation. PMID:16453573

Paszkowski, J; Shillito, R D; Saul, M; Mandk, V; Hohn, T; Hohn, B; Potrykus, I

1984-12-01

390

Direct Measurement of Turbulent Shear  

NASA Astrophysics Data System (ADS)

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(?) = /

Stefanus, Stefanus; Steers, Stanley; Goldburg, Walter

2010-11-01

391

Grouping principles in direct competition.  

PubMed

We (1) introduce a primed flanker task as an objective method to measure perceptual grouping, and (2) use it to directly compare the efficiency of different grouping cues in rapid visuomotor processing. In two experiments, centrally presented primes were succeeded by flanking targets with varying stimulus-onset asynchronies (SOAs). Primes and targets were grouped by the same or by different grouping cues (Exp. 1: brightness/shape, Exp. 2: brightness/size) and were consistent or inconsistent with respect to the required response. Subjective grouping strength was varied to identify its influence on overall response times, error rates, and priming effects, that served as a measure of visual feedforward processing. Our results show that stronger grouping in the targets enhanced overall response times while stronger grouping in the primes enhanced priming effects in motor responses. Also, we obtained differences between rapid visuomotor processing and the subjective impression with cues of brightness and shape but not with cues of brightness and size. Our findings establish the primed flanker task as an objective method to study the speeded visuomotor processing of grouping cues, making it a useful method for the comparative study of feedforward-transmitted base groupings (Roelfsema & Houtkamp, 2011). PMID:23764184

Schmidt, Filipp; Schmidt, Thomas

2013-06-11

392

Imaging goal-directed movement.  

PubMed

The main purpose of the present investigation was to determine how Shepard's (1968) second-order isomorphic principle relates to imaging goal-directed movement. Reports of movement times for actual and imaged movements were obtained using Fitts-type tapping tasks. Displays consisted of two different (referential) or two identical (nonreferential) stimulus pairs. In Experiments 1a and 1b, target width and amplitude were manipulated to produce two indexes of difficulty. In Experiments 2a and 2b, the index of difficulty was constant, and biases were created by indicating that movement time increased with decreases in target width or increases in amplitude. In all four experiments, reported movement time reflected Fitts' (1954) law for actual tapping and during early trials for referential imagery. In Experiments 1a and 1b, reported movement times for the two indexes of difficulty were similar for nonreferential imagery and at later trials for referential imagery. In Experiments 2a and 2b, reported movement times reflected the biases for nonreferential imagery and at later trials for referential imagery. The results suggest that propositional knowledge and information processing interact to control movement imagery. PMID:7777693

Kohl, R M; Fisicaro, S A

1995-03-01

393

Impact of antenna directivity for carrier sensing in high density WLAN using adaptive directional antenna  

Microsoft Academic Search

This paper describes impact of antenna directivity for carrier sensing on system throughput in high density wireless LAN (WLAN) using adaptive directional antenna. Adaptive directional antenna is effective to improve system throughput of WLAN, however it is necessary to clear the impact of antenna directivity used for carrier sensing in CSMA based WLAN since directional antenna may increase packet collisions

Masahiro UMEHIRA; Yohei OHTOMO

2010-01-01

394

Future directions in dialysis quantification.  

PubMed

The influence of dialysis prescription on outcome is well established, and currently the amount of dialysis prescribed is based on small molecular weight toxin removal as represented by the clearance of urea. The "normalized dose of dialysis" (Kt/V(urea)) concept is well established. Most techniques for dialysis quantification require that blood samples be taken at the beginning and after the completion of dialysis. The postdialysis sample, however, gives cause for concern because of the "rebound phenomenon" due to nonuniform distribution of urea among body compartments. Blood samples give "indirect" measures of dialysis quantification. Thus direct urea concentration measurements in dialysate may be superior in urea kinetic modeling and these may be made "real time" during dialysis. It is with real-time monitoring that future advances in dialysis quantification will take place. These will be of two types. The first will analyze blood water or dialysate samples for urea content multiple times throughout the treatment; the second will assess the on-line clearance of urea using surrogate molecules such as sodium chloride, the clearance being determined by conductivity measurements. On-line urea monitoring is based on the action of urease on urea in a water solution and measurement of the resultant ammonium ions, which are measured directly by a specific electrode or indirectly by conductivity changes. Differences in blood-side versus dialysate-side urea monitors exist which reflect the parameters they can provide, but with both, the standard urea kinetic measurements of Kt/V and nPCR (nPNA) are easily obtainable. A range of additional parameters can be derived from dialysate-side monitoring such as "whole-body Kt/V," "pretreatment urea mass" and "whole-body urea clearance," which are worthy of future studies to determine their roles in adequacy assessment. Conductivity clearance measurements are made by examining the conductivity differences between dialysate inlet and outlet measured at two different dialysate inlet concentrations. This allows for the calculation of the electrolyte (ionic) dialysance, which is equal to the "effective" urea clearance, that is, the clearance that takes into account recirculation effects that reduce hemodialysis efficiency. The continuous reading of effective ionic clearance will allow an average value for K to be obtained for that dialysis, and hence the parameter K x t as an indication of dialysis dose is easily and accurately obtained for every treatment. The conductivity technology is cheap and rugged, and thus expanded use can be expected. Urea monitors have an inherent cost and require maintenance, and perhaps will remain researchers' tools for the present. The methodologies can complement each other; the addition of an accurate and independent value for K to dialysate based urea monitoring is like having simultaneous blood- and dialysate-side monitoring, and allows further increase in measurable parameters. PMID:11489207

Lindsay, R M; Sternby, J

395

28 CFR 35.139 - Direct threat.  

Code of Federal Regulations, 2013 CFR

...or activities of that public entity when that individual poses a direct threat to the health or safety of others...individual poses a direct threat to the health or safety of others, a public entity must...

2013-07-01

396

28 CFR 36.208 - Direct threat.  

Code of Federal Regulations, 2013 CFR

...accommodations of that public accommodation when that individual poses a direct threat to the health or safety of others...individual poses a direct threat to the health or safety of others, a public accommodation...

2013-07-01

397

Datchik postoyannogo toka. (Direct current transducer).  

National Technical Information Service (NTIS)

A direct current transducer based on magnetic comparison of direct currents is discussed. The principle of operation of the transducer is considered, its blockdiagram, circuit diagram and technical solutions for some of its units are given. General zero d...

E. Batmanova G. G. Kazakova V. V. Kalinichenko

1991-01-01

398

Direction Estimation of Pedestrian from Images.  

National Technical Information Service (NTIS)

The capability of estimating the walking direction of people would be useful in many applications such as those involving autonomous cars and robots. We introduce an approach for estimating the walking direction of people from images, based on learning th...

H. Simizu T. Poggio

2003-01-01

399

Literature Survey on Direct Energy Machining.  

National Technical Information Service (NTIS)

The mechanism of various direct energy machining processes is presented. Machine requirements are discussed. Direct energy machining processes, at the present state of the art, are a breakthrough to the solution of shaping of materials which cannot be mac...

C. R. Hyland

1964-01-01

400

Outrunning Nature: Directed Evolution of Superior Biocatalysts  

ERIC Educational Resources Information Center

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.

Woodyer, Ryan; Chen, Wilfred; Zhao, Huimin

2004-01-01

401

Product directivity models for parametric loudspeakers.  

PubMed

In a recent work, the beamsteering characteristics of parametric loudspeakers were validated in an experiment. It was shown that based on the product directivity model, the locations and amplitudes of the mainlobe and grating lobes could be predicted within acceptable errors. However, the measured amplitudes of sidelobes have not been able to match the theoretical results accurately. In this paper, the original theories behind the product directivity model are revisited, and three modified product directivity models are proposed: (i) the advanced product directivity model, (ii) the exponential product directivity model, and (iii) the combined product directivity model. The proposed product directivity models take the radii of equivalent Gaussian sources into account and obtain better predictions of sidelobes for the difference frequency waves. From the comparison between measurement results and numerical solutions, all the proposed models outperform the original product directivity model in terms of selected sidelobe predictions by about 10 dB. PMID:22423691

Shi, Chuang; Gan, Woon-Seng

2012-03-01

402

77 FR 49705 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration...airworthiness directive (AD) for certain Airbus Model A318-112 and -121 airplanes...states: During structural part assembly in Airbus production line, some [wing] nuts...

2012-08-17

403

76 FR 73496 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration...directive (AD) that applies to certain Airbus Model A330-201, -202, -203, -223...applicability to aeroplanes which have embodied Airbus modification 49202, and...

2011-11-29

404

Directional light coupling from microdisk lasers  

Microsoft Academic Search

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.

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

1993-01-01

405

Outrunning Nature: Directed Evolution of Superior Biocatalysts  

ERIC Educational Resources Information Center

|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.|

Woodyer, Ryan; Chen, Wilfred; Zhao, Huimin

2004-01-01

406

Modeling of Rapid Direct Contact Condensation.  

National Technical Information Service (NTIS)

The focus of the study is on rapid direct-contact condensation phenomena, that is, direct contact condensation situations characterized by extremely high condensation rates and violent mixing at the liquid-vapor interface. Rapid condensation phenomena ari...

G. B. Wallis H. J. Richter J. A. Valenzuela P. H. Rothe

1985-01-01

407

Filtros Direcionais Em Microfita (Microstrip Directional Filters).  

National Technical Information Service (NTIS)

The results of an investigation of a microstrip directional filters are presented. Bandpass and bandstop travelling wave directional filters are designed to verify the design procedure. The performance obtained suggests the use of the travelling wave dire...

P. M. Marshall

1984-01-01

408

Implementation Issues for Consumer-Directed Programs  

Microsoft Academic Search

An increasing number of aging community providers and consumers support consumer-direction (CD) in long-term care services. In regard to devolution, consumer-direction goes beyond the usual approach of shifting responsibilities from the federal government to state governments to bring programs closer to the people. Consumer-direction goes even further by placing resources directly in the hands of consumers.Yet, many questions remain unanswered

Lori Simonrusinowitz; Lori N. Marks; Dawn M. Loughlin; Sharon M. Desmond; Kevin J. Mahoney; B. Lee Zacharias; Marie R. Squillace; Ann Marie Allison

2002-01-01

409

Terahertz pipe-waveguide-based directional couplers.  

PubMed

We experimentally demonstrate a terahertz (THz) leaky mode directional coupler for future THz applications. The proposed directional coupler comprises two square pipe waveguides. The coupling efficiency is investigated for different frequencies, polarizations, and core sizes. Rectangular pipe-waveguide-based directional couplers and the issue of insertion loss are also discussed. It is found that the THz directional coupler works most efficiently in the minimal-attenuation wavelength regime. PMID:22274271

Lu, Jen-Tang; Lai, Chih-Hsien; Tseng, Tzu-Fang; Chen, Hua; Tsai, Yuan-Fu; Hwang, Yuh-Jing; Chang, Hung-Chun; Sun, Chi-Kuang

2011-12-19

410

Spectral analyzer and direction indicator (SADI) system  

NASA Astrophysics Data System (ADS)

The spectral analyzer and direction indicator (SADI) system is an electro-optic sensor that can determine both the spectral content and direction of the source of a single pulse of radiated energy. In its simplest form, it can determine the direction of the source in one dimension. Directional information in two dimensions requires the addition of some electronics and, in some configurations, optics. Various degrees of electronic processing sophistication may yield the pulse shape, and its spectral and spatial distribution.

Welner, Jerome M.

1988-01-01

411

Teaching Learners To Be Self-Directed  

Microsoft Academic Search

Based on the Situational Leadership model of Hersey and Blanchard (1988), the Staged Self-Directed Learning Model proposes that learners advance through stages of increasing self-direction and that teachers can help or hinder that development. Good teaching matches the learner's stage of self-direction and helps the learner advance toward greater self-direction. Specific methods are proposed for teaching students at each stage,

Gerald O. Grow

1991-01-01

412

Hydrothermal industrialization: direct heat development. Final report  

SciTech Connect

A description of hydrothermal resources suitable for direct applications, their associated temperatures, geographic distribution and developable capacity are given. An overview of the hydrothermal direct-heat development infrastructure is presented. Development activity is highlighted by examining known and planned geothermal direct-use applications. Underlying assumptions and results for three studies conducted to determine direct-use market penetration of geothermal energy are discussed.

Not Available

1982-05-01

413

Comparison of direct and rejection sampling methods  

Microsoft Academic Search

In this paper, the authors compare direct sampling methods with rejection sampling for some common probability density functions (pdf's) used in Monte Carlo codes. Timing results obtained on several types of engineering workstation indicate that the direct sampling methods are always competitive with and usually faster than rejection schemes. Direct methods also involve coding that is easier to understand and

F. B. Brown; J. Vujic

1993-01-01

414

Geothermal direct use engineering and design guidebook  

Microsoft Academic Search

The Geothermal Direct Use Engineering and Design Guidebook is designed to be a comprehensive, thoroughly practical reference guide for engineers and designers of direct heat projects. These projects could include the conversion of geothermal energy into space heating cooling of buildings, district heating, greenhouse heating, aquaculture and industrial processing. The Guidebook is directed at understanding the nature of geothermal resources

R. G. Bloomquist; G. Culver; P. F. Ellis; C. Higbee; C. Kindle; P. J. Lienau; B. C. Lunis; K. Rafferty; S. Stiger; P. M. Wright

1989-01-01

415

Outcome, Process & Power in Direct Democracy  

Microsoft Academic Search

Based on survey data for Switzerland, new empirical findings on direct democracy are presented. In the first part, we show that, on average, public employees receive lower financial compensation under more direct democratic institutions. However, top bureaucrats are more constrained in direct de m ocracies and have to be compensated by higher wages for that loss of power. In the

Bruno S. Frey; Marcel Kucher; Alois Stutzer

1999-01-01

416

Determining Directional Dependency in Causal Associations  

ERIC Educational Resources Information Center

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

Pornprasertmanit, Sunthud; Little, Todd D.

2012-01-01

417

The European Biotech Directive: Past as Prologue  

Microsoft Academic Search

The directive on the legal protection of biotechnological inventions (the Biotech Directive) represents the end of a decade-long dialogue on how best to encourage biotechnology innovation in Europe while addressing ethical concerns. The Biotech Directive represents an interesting compromise between Parliament, Commission, and Council based on divergent policy concerns, treaty limitations, and international trade rules. In this article, the authors

E. Richard Gold; Alain Gallochat

2001-01-01

418

Special section on beam direct conversion  

Microsoft Academic Search

In fusion, there are two possible direct energy conversion methods: plasma direct energy conversion (PDC), which recovers the plasma energy leaking out of the confined region, and beam direct energy conversion (BDC), which recovers the unneutralized energetic ion energy in a neutral beam injection (NBI) system used for plasma heating and to sustain current. In the very powerful near-term NBI

Yoshikawa

1990-01-01

419

Self-Directed Learning: Application and Research.  

ERIC Educational Resources Information Center

|These 23 papers provide as complete a picture as possible of the current efforts in self-directed learning application and research. The papers are: "Learning about Self-Directed Learning" (Long); "Philosophical, Psychological, and Practical Justifications for Studying Self-Direction in Learning" (Long); "In Search of Consensus in the Study of

Long, Huey B.; And Others

420

Implementation of the Database Machine DIRECT  

Microsoft Academic Search

DIRECT is a multiprocessor database machine designed and implemented at the University of Wisconsin. This paper describes our experiences with the implementation of DIRECT. We start with a brief overview of the original machine proposal and how it differs from what was actually implemented. We then describe the structure of the DIRECT software. This includes software on host computers that

Haran Boral; David J. Dewitt; Dina Friedland; Nancy F. Jarrell; W. Kevin Wilkinson

1982-01-01

421

Direction Concepts in Wayfinding Assistance Systems  

Microsoft Academic Search

We report new findings about the mental representation of direction concepts and how these findings may revise for- mal models of spatial reasoning and navigation assistance systems. Research on formal models of direction concepts has a long tradition in AI. While early models where de- signed for unstructured space, for example, reasoning about cardinal directions, research on the influence of

A. Klippel; C. Dewey; M. Knauff; K.-F. Richter; D. R. Montello; C. Freksa; E.-A. Loeliger

422

A Model of Direct and Intermediated Sales  

Microsoft Academic Search

We examine a model in which an upstream firm can sell directly online and through heterogeneous intermediaries to heterogeneous consumers engaging in time-consuming search. Direct online sales may be more or less convenient and involve costly returns if the good fits consumers poorly. Direct selling appeals to higher-value consumers and increases the upstream firm's profits by allowing price discrimination. Competition

Terrence Hendershott; Jie Zhang

2006-01-01

423

Manufacturer's direct selling and pricing strategy  

Microsoft Academic Search

Development of e-business and logistics stimulates manufacturers to sell their products directly to customers online besides traditional channels through independent retailers. This paper studies the manufacturer's direct selling decision under an entry game framework which conceptualizes price competition between the manufacturer and its independent retailers. The direct channel helps the manufacturer to absorb consumer segment otherwise would not purchase from

Shuo Huang; Qing Ye

2010-01-01

424

Direct selling as the next channel  

Microsoft Academic Search

Purpose The paper aims to describe the application of direct selling, the process of selling a consumer product or service from one person to another, in an environment that is not a permanent retail location. Design\\/methodology\\/approach The paper explores the application of direct selling from the perspective of companies that have built their business around direct selling and

Dennis L. Duffy

2005-01-01

425

Pyramidal directional filter banks and curvelets  

Microsoft Academic Search

A flexible multiscale and directional representation for im ages is proposed. The scheme combines directional filter banks with the Laplacian pyramid to provides a sparse representation for t wo- dimensional piecewise smooth signals resembling images. The underlying expansion is a frame and can be designed to be a tight frame. Pyramidal directional filter banks provide an e ffective method to

Minh N. Dot; Martin Vetterlits

2001-01-01

426

Self Directed Learning and Self Management. Symposium.  

ERIC Educational Resources Information Center

This document contains three papers from a symposium on self-directed learning and self-management. "Validating a More-Dimensional Conception of Self-Directed Learning" (Gerald A. Straka, Cornelia Schaefer) discusses the development and validation of a conception of self-directed learning as a dynamic interplay between behavior, information,

2002

427

How to be a Direct Realist  

Microsoft Academic Search

Many philosophers claim to hold a view of perceptual experience that is a version of, or is at least compatible with, direct realism. It is usually left unclear, however, exactly what direct realism is, and what is involved in affirming it. In this essay I will identify the core commitments of direct realism, and argue that representationalist theories of perceptual

James Genone

428

Presenting directions with a vibrotactile torso display  

Microsoft Academic Search

Vibrotactile displays covering the torso present spatial information in an intuitive way since the stimuli are directly mapped to the body coordinates; left is left, front is front, etc. The present study investigated the direction in the horizontal plane to which a specific torso location is mapped using a 15 tactor linear display. Participants indicated the observed external direction of

Jan BF Van Erp

2005-01-01

429

Cooperative two-dimensional directed transport  

Microsoft Academic Search

A mechanism for the cooperative directed transport in two-dimensional ratchet potentials is proposed. With the aid of mutual couplings among particles, coordinated unidirectional motion along the ratchet direction can be achieved by transforming the energy from the transversal rocking force (periodic or stochastic) to the work in the longitude direction. Analytical predictions on the relation between the current and other

Zhigang Zheng; Hongbin Chen

2010-01-01

430

The Direct Satellite Connection: Definitions and Prospects.  

ERIC Educational Resources Information Center

|Defines direct satellite broadcasting as the transmission of broadcast signals via high-powered satellites that permit direct reception of television or radio programs by means of small antennas. Outlines American, European, and Japanese plans for direct-to-home television reception and implications for the broadcasting industry. (JMF)|

Wigand, Rolf T.

1980-01-01

431

Nursing Home Resident Use of Care Directives.  

National Technical Information Service (NTIS)

To determine the correlates of care directive use in the nursing home. Care directives examined include advance directives and do-not-resuscitate (DNR) orders. The authors analyzed a version of the Minimum Data Set (MDS+) from a single state. The authors ...

D. N. Suri B. L. Egleston J. A. Brody M. A. Rudberg

1999-01-01

432

Mapping Directly Imaged Giant Exoplanets  

NASA Astrophysics Data System (ADS)

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 H2O, CH4, 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.

Kostov, Veselin; Apai, Dniel

2013-01-01

433

DIRECT LIQUEFACTION PROOF OF CONCEPT  

SciTech Connect

The eighth bench scale test of POC program, Run PB-08, was successfully completed from August 8 to August 26, 1997. A total of five operating conditions were tested aiming at evaluating the reactivity of different pyrolysis oils in liquefaction of a Wyoming sub-bituminous coal (Black Thunder coal). For the first time, water soluble promoters were incorporated into the iron-based GelCat to improve the dispersion of the promoter metals in the feed blend. The concentration of the active metals, Mo and Fe, was 100 and 1000 ppm of moisture-free coal, respectively. Black Thunder coal used in this run was the same batch as tested in HTI?s Run POC-02. Similar to Runs PB-01 through 7, this run employed two back mixed slurry reactors, an interstage gas/slurry separator and a direct-coupled hydrotreater. In addition to the hot vapor from the second stage separator, the first stage separator overhead liquid was also fed to the hydrotreater, which was packed with Criterion C-411 hydrotreating catalyst. Pyrolysis oil was produced off-line from a pyrolysis unit acquired from University of Wyoming. Solids rejection was achieved by purging out pressure filter solid. The recycle solvents consisted of O-6 separator bottoms and pressure filter liquid (PFL). The Run PB-08 proceeded very smoothly without any interruptions. Coal conversion consistently above 90W% was achieved. High resid conversion and distillate yield have been obtained from co-processing of coal and 343C+ (650F+) pyrolysis oil. Light gas (C1-C3 ) yield was minimized and hydrogen consumption was reduced due to the introduction of pyrolysis oil, compared with conventional coal-derived solvent. Catalytic activity was improved by incorporating a promoter metal into the iron-based GelCat. It seemed that lowering the first stage temperature to 435C might increase the hydrogenation function of the promoter metal. In comparison with previous coal-waste coprocessing run (PB-06), significant improvements in the process performance were achieved due to catalyst modification and integration of pyrolysis technique into liquefaction.

NONE

1998-09-01

434

AIRTV: Broadband Direct to Aircraft  

NASA Astrophysics Data System (ADS)

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

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

2002-01-01

435

Directional emittance corrections for thermal infrared imaging  

NASA Astrophysics Data System (ADS)

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.

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

1992-04-01

436

Black covering in direct solar dryers  

SciTech Connect

Direct solar dryers, such as greenhouse solar dryers, account for a considerable amount of all solar dryers. Under normal conditions, the drying commodities in direct solar dryers absorb solar energy directly. However, many drying commodities have low solar absorbtance, and this affects the efficiency of such solar dryers. An experiment has been carried out to show the possibility of using high absorption materials as a cover to improve drying conditions in direct solar dryers. Experimental results show that using black materials in direct solar dryers has tangible results: the temperature of drying commodities is higher and the drying rate is improved.

Xiaoren, Sun (Shanxi Information Institute of Science and Technology (China))

1989-01-01

437

The persistence of directivity in small earthquakes  

USGS Publications Warehouse

We derive a simple inversion of peak ground acceleration (PGA) or peak ground velocity (PGV) for rupture direction and rupture velocity and then test this inversion on the peak motions obtained from seven 3.5 ??? M ??? 4.1 earthquakes that occurred in two clusters in November 2002 and February 2003 near San Ramon, California. These clusters were located on two orthogonal strike-slip faults so that the events share the same approximate focal mechanism but not the same fault plane. Three earthquakes exhibit strong directivity, but the other four earthquakes exhibit relatively weak directivity. We use the residual PGAs and PGVs from the other six events to determine station corrections for each earthquake. The inferred rupture directions unambiguously identify the fault plane for the three earthquakes with strong directivity and for three of the four earthquakes with weak directivity. The events with strong directivity have fast rupture velocities (0.63????? v ??? 0.87??); the events with weak directivity either rupture more slowly (0.17????? v ???0.35??) or bilaterally. The simple unilateral inversion cannot distinguish between slow and bilateral ruptures: adding a bilateral rupture component degrades the fit of the rupture directions to the fault planes. By comparing PGAs from the events with strong and weak directivity, we show how an up-dip rupture in small events can distort the attenuation of peak ground motion with distance. When we compare the rupture directions of the earthquakes to the location of aftershocks in the two clusters, we find than almost all the aftershocks of the three earthquakes with strong directivity occur within 70?? of the direction of rupture.

Boatwright, J.

2007-01-01

438

Electrodeposition of PtRu nanoparticles on multi-walled carbon nanotubes: Application in sensitive voltammetric determination of methyldopa  

Microsoft Academic Search

A modified glassy carbon electrode, prepared by potentiostatic electrodeposition of platinumruthenium nanoparticles (PtRuNPs) onto a multi-walled carbon nanotube (MWCNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric responses toward methyldopa (m-dopa) compared to glassy carbon electrodes individually coated with MWCNT or PtRuNPs. The surface morphology and nature of the hybrid film (PtRuNPs\\/MWCNT) deposited on glassy carbon electrodes

Saeed Shahrokhian; Shokoufeh Rastgar

439

Pt and PtRu nanoparticles decorated polypyrrole\\/multiwalled carbon nanotubes and their catalytic activity towards methanol oxidation  

Microsoft Academic Search

Conducting polymer composite films comprised of polypyrrole (PPy) and multiwalled carbon nanotubes (MWCNTs) [PPyCNT] were synthesized by in situ polymerization of pyrrole on carbon nanotubes in 0.1M HCl containing (NH4)S2O8 as oxidizing agent over a temperature range of 05C. Pt nanoparticles are deposited on PPyCNT composite films by chemical reduction of H2PtCl6 using HCHO as reducing agent at pH=11 [Pt\\/PPyCNT].

Vaithilingam Selvaraj; Muthukaruppan Alagar

2007-01-01

440

Dispersion of Pt\\/Ru catalyst onto arc-soot and its performance evaluation as DMFC electrode  

Microsoft Academic Search

The arc-soot (AS) nano-carbon was synthesized by using arc discharge apparatuses which were the conventional arc apparatus and the new twin-torch-arc apparatus. AS synthesized with the conventional arc apparatus contained cocoon-like carbon nano-horn (CNH), dahlia-like CNH, and graphite ball. On the other hand, AS which was synthesized using the new twin-torch-arc apparatus contained mainly cocoon-like CNH and dahlia-like CNH, and

S. Oke; K. Higashi; K. Shinohara; Y. Izumi; H. Takikawa; T. Sakakibara; S. Itoh; T. Yamaura; G. Xu; K. Miura; K. Yoshikawa; S. Sugawara; T. Okawa; N. Aoyagi

2008-01-01

441

Relationship between Laboratory Measures of Directional Advantage and Everyday Success with Directional Microphone Hearing Aids  

Microsoft Academic Search

The improvement in speech recognition in noise obtained with directional microphones compared to omnidirectional microphones is referred to as the directional advantage. Laboratory studies have revealed substantial differ- ences in the magnitude of the directional advantage across hearing-impaired listeners. This investigation examined whether persons who were successful users of directional microphone hearing aids in everyday living tended to obtain a

Mary T. Cord; Rauna K. Surr; Brian E. Walden; Ole Dyrlund

2004-01-01

442

Bedform alignment in directionally varying flows  

USGS Publications Warehouse

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.

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

1987-01-01

443

Machine-Learning Research Four Current Directions  

Microsoft Academic Search

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

Thomas G. Dietterich

1997-01-01

444

Student directed learning from biographical information systems  

Microsoft Academic Search

Compared the effect of a student-directed instructional approach to a system-directed approach by studying how 64 high school seniors learned about Freud through an information system. The effect of student conceptual level (CL) was also investigated by use of an extreme group design. The student-directed approach was superior for knowledge acquisition, but no differences due to instructional approach were found

Joyce E. Noy; David E. Hunt

1972-01-01

445

Neural Processes Involved in Directing Attention  

Microsoft Academic Search

Neural processes associated with two aspects of visual-spatial attention were investigated with event-related potential (ERPs): those that direct spatial attention to a given point in space and those that modulate the processing of sensory input after attention has been directed. The subjects were 6- to 9-year-old children (51 boys and 35 girls). An arrow cue directed attention from the central

M. Russell Harter; Steven L. Miller; Natalie J. Price; Margaret E. LaLonde; Alvin L. Keyes

1989-01-01

446

Imaging of directional distributed noise sources  

Microsoft Academic Search

This study relates to the acoustic imaging of noise sources that are distributed and strongly directional, such as in turbulent jets. The goal is to generate high-resolution noise source maps with self-consistency, i.e., their integration over the extent of the noise source region gives the far-field pressure auto-spectrum for a particular emission direction. Self-consistency is possible by including a directivity

Dimitri Papamoschou

2011-01-01

447

Direct Geocoding - is Aerial Triangulation Obsolete?  

Microsoft Academic Search

By direct geocoding or direct georeferencing, i.e. the direct measurement of the exterior orientation of an imaging sensor using an integrated system consisting of receivers of the Global Positioning System (GPS) and a strap-down Inertial Measurement Unit (IMU), required ground control and tie point information could be reduced or eliminated significantly. Using integrated GPS\\/inertial systems many applications can be realized

MICHAEL CRAMER; D. Fritsch; R. Spiller; Wichmann Verlag

1999-01-01

448

Directed diffusion for wireless sensor networking  

Microsoft Academic Search

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

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

2003-01-01

449

The far future of exoplanet direct characterization.  

PubMed

We describe future steps in the direct characterization of habitable exoplanets subsequent to medium and large mission projects currently underway and investigate the benefits of spectroscopic and direct imaging approaches. We show that, after third- and fourth-generation missions have been conducted over the course of the next 100 years, a significant amount of time will lapse before we will have the capability to observe directly the morphology of extrasolar organisms. PMID:20307188

Schneider, Jean; Lger, Alain; Fridlund, Malcolm; White, Glenn J; Eiroa, Carlos; Henning, Thomas; Herbst, Tom; Lammer, Helmut; Liseau, Ren; Paresce, Francesco; Penny, Alan; Quirrenbach, Andreas; Rttgering, Huub; Selsis, Franck; Beichman, Charles; Danchi, William; Kaltenegger, Lisa; Lunine, Jonathan; Stam, Daphne; Tinetti, Giovanna

450

Direct photons in PHENIX at the RHIC  

SciTech Connect

PHENIX results on direct photon production in p+p, d+Au, Cu+Cu and Au+Au collisions are presented. Direct photon yield at high p{sub T} is consistent with NLO pQCD calculations in all systems. In heavy ion collisions at low p{sub T} direct photons exhibit an order of magnitude exponential shape enhancement consistent with thermal emission from quark gluon plasma (QGP). The thermal nature of this enhancement is further confirmed by the large elliptic flow of direct photons below p{sub T} {approx} 5 GeV/c.

Kistenev E.; PHENIX Collaboration

2011-11-10

451

Rupture directivity of small earthquakes at Parkfield  

NASA Astrophysics Data System (ADS)

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> <div class="credits"> <p class="dwt_author">Kane, Deborah L.; Shearer, Peter M.; Goertz-Allmann, Bettina P.; Vernon, Frank L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">452</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/12467370"> <span id="translatedtitle"><span class="hlt">Directivity</span> of different hearing aid microphone locations.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">In this study, we present a new method to derive a single-number measure of the <span class="hlt">directivity</span> of hearing aids. The method is an extension of the conventional <span class="hlt">directivity</span> index (DI), and is called overall <span class="hlt">directivity</span> index (ODI). The <span class="hlt">directivities</span> of five different hearing aid styles were compared with that of the open ear. The behind-the-ear (BTE) style showed the lowest <span class="hlt">directionality</span> compared to the other hearing aid styles and the open ear. There were only minor differences in <span class="hlt">directivity</span> between any of the four different hearing aid styles placed in the ear and of the open ear canal. The conventional measure of DI is less suitable for hearing aids, because it ignores sound coming from other than the frontal <span class="hlt">direction</span>. To quantify <span class="hlt">directionality</span> of a hearing aid in a real-life situation, we suggest the single-number ODI, weighted with the articulation index and related to a listening segment of 0-30 degrees. An application of the data is shown for a BTE with a <span class="hlt">directional</span> microphone. PMID:12467370</p> <div class="credits"> <p class="dwt_author">Olsen, Henrik L; Hagerman, Bjrn</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">453</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1490365"> <span id="translatedtitle">Family physicians' attitudes toward advance <span class="hlt">directives</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">OBJECTIVE: To examine the attitudes toward, the experience with and the knowledge of advance <span class="hlt">directives</span> of family physicians in Ontario. DESIGN: Cross-sectional survey. PARTICIPANTS: A questionnaire was mailed to 1000 family physicians, representing a random sample of one-third of the active members of the Ontario College of Family Physicians; 643 (64%) responded. RESULTS: In all, 86% of the physicians favoured the use of advance <span class="hlt">directives</span>, but only 19% had ever discussed them with more than 10 patients. Most of the physicians agreed with statements supporting the use of advance <span class="hlt">directives</span> and disagreed with statements opposing their use. Of the respondents 80% reported that they had never used a <span class="hlt">directive</span> in managing an incompetent patient. Of the physicians who responded that they had such experience, over half said that they had not always followed the <span class="hlt">directions</span> contained in the <span class="hlt">directive</span>. The proportions of physicians who responded that certain patient groups should be offered the opportunity to complete an advance <span class="hlt">directive</span> were 96% for terminally ill patients, 95% for chronically ill patients, 85% for people with human immunodeficiency virus infection, 77% for people over 65 years of age, 43% for all adults, 40% for people admitted to hospital on an elective basis and 33% for people admitted on an emergency basis. The proportions of physicians who felt that the following strategies would encourage them to offer advance <span class="hlt">directives</span> to their patients were 92% for public education, 90% for professional education, 89% for legislation protecting physicians against liability when following a <span class="hlt">directive</span>, 80% for legislation supporting the use of <span class="hlt">directives</span>, 79% for hospital policy supporting the use of <span class="hlt">directives</span>, 73% for reimbursement for time spent discussing <span class="hlt">directives</span> with patients and 64% for hospital policy requiring that all patients be routinely offered the opportunity to complete a <span class="hlt">directive</span> at the time of admission. CONCLUSIONS: Family physicians favour advance <span class="hlt">directives</span> but use them infrequently. Most physicians support offering them to terminally or chronically ill patients but not to all patients at the time of admission to hospital. Although governments emphasize legislation, most physicians believe that public and professional education programs would be at least as likely as legislation to encourage them to offer advance <span class="hlt">directives</span> to their patients.</p> <div class="credits"> <p class="dwt_author">Hughes, D L; Singer, P A</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">454</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60101214"> <span id="translatedtitle"><span class="hlt">Direct</span> contact, binary fluid geothermal boiler</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Energy is extracted from geothermal brines by <span class="hlt">direct</span> contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is <span class="hlt">directed</span> to a turbine.</p> <div class="credits"> <p class="dwt_author">Rapier</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">455</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60100945"> <span id="translatedtitle"><span class="hlt">Direct</span> contact, binary fluid geothermal boiler</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Energy is extracted from geothermal brines by <span class="hlt">direct</span> contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is <span class="hlt">directed</span> to a turbine.</p> <div class="credits"> <p class="dwt_author">Rapier</p> <p class="dwt_publisher"></p> <p class="publishDate">1979-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">456</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013APS..APRC11009M"> <span id="translatedtitle">The DRIFT <span class="hlt">Directional</span> Dark Matter Detector</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The DRIFT dark matter detector is a 1 cubic meter scale TPC with <span class="hlt">directional</span> sensitivity to WIMP recoils operating in the Boulby Mine in England. The <span class="hlt">directional</span> sensitivity allows DRIFT to detect the sidereal modulation of the WIMP recoils and provide an unambiguous confirmation of a dark matter interaction. We present current limits from DRIFT and provide a brief update on background reduction efforts.</p> <div class="credits"> <p class="dwt_author">Miller, Eric</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">457</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.fasebj.org/cgi/reprint/11/7/535.pdf"> <span id="translatedtitle">New <span class="hlt">directions</span> in breast cancer research</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Research in breast cancer extends in many <span class="hlt">directions</span>, stimulated by concerns related to the high incidence of the disease and the relative un- predictability of its clinical course. Examples of work in several <span class="hlt">directions</span> are presented here arranged by four levels of analysis. 1) Molecular, intracellular events (molecular genetics). Recent identification of genes that predispose to breast cancer, and the</p> <div class="credits"> <p class="dwt_author">SANDRA R. WOLMAN; GLORIA H. HEPPNER; ERIC WOLMAN</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">458</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55439525"> <span id="translatedtitle"><span class="hlt">Directional</span> Coupling for Quantum Computing and Communication</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We introduce the concept of <span class="hlt">directional</span> coupling, i.e., the selective transfer of a state between adjacent quantum wires, in the context of quantum computing and communication. Our analysis rests upon a mathematical analogy between a dual-channel <span class="hlt">directional</span> coupler and a composite spin system.</p> <div class="credits"> <p class="dwt_author">Georgios M. Nikolopoulos</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">459</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/12714267"> <span id="translatedtitle"><span class="hlt">Directional</span> Coupling for Quantum Computing and Communication</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We introduce the concept of <span class="hlt">directional</span> coupling, i.e., the selective\\u000atransfer of a state between adjacent quantum wires, in the context of quantum\\u000acomputing and short-distance communication. Our analysis rests upon a\\u000amathematical analogy between a dual-channel <span class="hlt">directional</span> coupler and a composite\\u000aspin system.</p> <div class="credits"> <p class="dwt_author">Georgios M. Nikolopoulos</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">460</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/47915616"> <span id="translatedtitle">Profit, <span class="hlt">Directional</span> Distance Functions, and Nerlovian Efficiency</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The <span class="hlt">directional</span> technology distance function is introduced, given an interpretation as a min-max, and compared with other functional representations of the technology including the Shephard input and output distance functions and the McFadden gauge function. A dual correspondence is developed between the <span class="hlt">directional</span> technology distance function and the profit function, and it is shown that all previous dual correspondences are</p> <div class="credits"> <p class="dwt_author">R. G. Chambers; Y. Chung; R. Fre</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_22");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">461</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/18921513"> <span id="translatedtitle">Flat <span class="hlt">directions</span> in de Sitter space</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The one loop level effective potential along the flat <span class="hlt">direction</span> in global supersymmetric models is evaluated in de Sitter space. In flat space the <span class="hlt">direction</span> phi only has a curvature determined by the supersymmetry soft breaking mass term m2phi2 and in the supersymmetric limit m-->0 it receives no radiative corrections because of the nonrenormalization theorem. In this paper we show</p> <div class="credits"> <p class="dwt_author">Hiroshi Suzuki; Masahiro Tanaka</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">462</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/27662638"> <span id="translatedtitle"><span class="hlt">Directionally</span> Euclidean Structures of Banach Spaces</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We study spaces with <span class="hlt">directionally</span> asymptotically controlled ellipsoids approximating the unit ball in finite-dimensions. These ellipsoids are the unique minimum volume ellipsoids, which contain the unit ball of the corresponding finite-dimensional subspace. The <span class="hlt">directional</span> control here means that we evaluate the ellipsoids with a given functional of the dual space. The term asymptotical refers to the fact that we take</p> <div class="credits"> <p class="dwt_author">Jarno Talponen</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">463</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=PB2011102253"> <span id="translatedtitle">Rodent Depredation-A <span class="hlt">Direct</span> Seeding Problem.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">Foresters have known for a long time that seed-eating rodents, birds, and insects must be circumvented before <span class="hlt">direct</span> seeding can be successful. Advances have been made in reducing losses in the <span class="hlt">direct</span> seeding of pine by the use of chemical repellents, and...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1965-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">464</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/FR-2010-05-28/pdf/2010-12834.pdf"> <span id="translatedtitle">75 FR 29915 - <span class="hlt">Direct</span> Final Rulemaking Procedures</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013</a></p> <p class="result-summary">...occurs, FMCSA will publish a notice in the Federal Register withdrawing the <span class="hlt">direct</span> final rule before it goes into effect. Arkema Incorporated inquired about the number of days FMCSA is considering for a <span class="hlt">direct</span> final rule to become effective after the...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-28</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">465</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50883065"> <span id="translatedtitle">Performance issues with <span class="hlt">directional</span> comparison blocking schemes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Distance and <span class="hlt">directional</span> overcurrent protection can provide 100 percent coverage of transmission or subtransmission feeders through the use of teleprotection (communications-assisted tripping) schemes. We briefly review in this paper various types of teleprotection schemes and then present principles to successfully apply a <span class="hlt">directional</span> comparison blocking scheme (DCB). We amplify these principles by examining the reasons why incorrect tripping occurred on</p> <div class="credits"> <p class="dwt_author">Ian Stevens; Normann Fischer; Bogdan Kasztenny</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">466</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=happen+AND+everyone&id=EJ899933"> <span id="translatedtitle">Hopes and <span class="hlt">Directions</span> for the Future</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">|Many significant changes have taken place in higher education since the first issue of "New <span class="hlt">Directions</span> for Teaching and Learning" (NDTL) was published in 1980. The purpose of this final chapter in this issue is to consider the <span class="hlt">directions</span> that higher education may be taking in the future. Although it is difficult to predict accurately what will</p> <div class="credits"> <p class="dwt_author">Wehlburg, Catherine M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">467</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/details.jsp?query_id=0&page=0&ostiID=865640"> <span id="translatedtitle"><span class="hlt">Direct</span> fired absorption machine flue gas recuperator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A recuperator which recovers heat from a gas, generally the combustion gas of a <span class="hlt">direct</span>-fired generator of an absorption machine. The recuperator includes a housing with liquid flowing therethrough, the liquid being in <span class="hlt">direct</span> contact with the combustion gas for increasing the effectiveness of the heat transfer between the gas and the liquid.</p> <div class="credits"> <p class="dwt_author">Reimann, Robert C. (Lafayette, NY); Root, Richard A. (Spokane, WA)</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">468</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.cs.clemson.edu/~luofeng/course/2009fall/810/projects/Learning%20to%20Trade%20via%20Direct%20Reinforcement.pdf"> <span id="translatedtitle">Learning to trade via <span class="hlt">direct</span> reinforcement</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We present methods for optimizing portfolios, asset allocations, and trading systems based on <span class="hlt">direct</span> reinforcement (DR). In this approach, investment decision-making is viewed as a stochastic control problem, and strategies are discovered <span class="hlt">directly</span>. We present an adaptive algorithm called recurrent reinforcement learning (RRL) for discovering investment policies. The need to build forecasting models is eliminated, and better trading performance is</p> <div class="credits"> <p class="dwt_author">John Moody; Matthew Saffell</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">469</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26377723"> <span id="translatedtitle">Catalysts for <span class="hlt">direct</span> ethanol fuel cells</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">By comparing the performance of fuel cells operating on some low molecular weight alcohols, it resulted that ethanol may replace methanol in a <span class="hlt">direct</span> alcohol fuel cell. To improve the performance of a <span class="hlt">direct</span> ethanol fuel cell (DEFC), it is of great importance to develop anode catalysts for ethanol electro-oxidation more active than platinum alone. This paper presents an overview</p> <div class="credits"> <p class="dwt_author">Ermete Antolini</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">470</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/31972399"> <span id="translatedtitle"><span class="hlt">Direct</span> inguinal hernias in children: laparoscopic aspects</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Among 109 children treated laparoscopically for inguinal hernias, 5 had <span class="hlt">direct</span> hernias, more than would normally be anticipated.\\u000a Two of the hernias were recurrences of indirect hernias operated upon previously using the open technique. <span class="hlt">Direct</span> hernias\\u000a are easier to detect with the laparoscopic technique.</p> <div class="credits"> <p class="dwt_author">F. Schier</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">471</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53482273"> <span id="translatedtitle"><span class="hlt">Direct</span> energy conversion for fusion power</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The potential importance of <span class="hlt">direct</span> energy conversion to the long-term development of fusion power is discussed with stress on the possibility of alleviating waste heat problems. This is envisioned to be crucial for any central power station in the 21st century. Two approaches, <span class="hlt">direct</span> collection and magnetic expansion, are reviewed. While other techniques may be possible, none have received sufficient</p> <div class="credits"> <p class="dwt_author">G. H. Miley</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">472</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/43274276"> <span id="translatedtitle"><span class="hlt">Direct</span> Discrimination, Indirect Discrimination and Autonomy</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Western liberal democracies tend to impose duties on public and private bodies that are often formulated as an obligation not to discriminate. For instance, the European Union prohibits <span class="hlt">direct</span> and indirect discrimination on certain grounds in certain contexts. Under this model, indirect discrimination involves a measure that, although it does not <span class="hlt">directly</span> (i.e. explicitly) discriminate on the basis of a</p> <div class="credits"> <p class="dwt_author">Oran Doyle</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">473</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/35413532"> <span id="translatedtitle">Lights can reverse illusory <span class="hlt">directional</span> hearing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Adding brief flashes of light to a train of auditory clicks [R. Hari, Illusory <span class="hlt">directional</span> hearing in humans, Neurosci. Lett. 189 (1995) 2930] can alter the sounds perceived location within the head. In an experimental procedure adopted from Hari [R. Hari, Illusory <span class="hlt">directional</span> hearing in humans, Neurosci. Lett. 189 (1995) 2930], 16 observers listened over headphones to 8 binaural clicks</p> <div class="credits"> <p class="dwt_author">Ashley Mays; James Schirillo</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">474</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=DE90012668"> <span id="translatedtitle">Recent results on <span class="hlt">direct</span> photons from CDF.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">We report on preliminary measurements of <span class="hlt">direct</span> photons in (bar p)p collisions at (radical)s = 1.8 TeV from the 1988--89 run of the Collider Detector at Fermilab (CDF). The inclusive <span class="hlt">direct</span> photon cross section, measured for photon transverse momentum in ...</p> <div class="credits"> <p class="dwt_author">R. M. Harris</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">475</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cjp.sagepub.com/cgi/reprint/18/4/395.pdf"> <span id="translatedtitle">Density, Inmate Assaults, and <span class="hlt">Direct</span> Supervision Jails</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Researchers have completed several studies on the effects of density on violence in prisons and jails, but little work has been done on density's impact on <span class="hlt">direct</span> supervision jails. <span class="hlt">Direct</span> supervision facilities, also known as new generation jails, were created by the Federal Bureau of Prisons with the goal of reducing violence, suicide and disorder. Given the crowded conditions in</p> <div class="credits"> <p class="dwt_author">Christine Tartaro; Marissa P. Levy</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">476</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/41164785"> <span id="translatedtitle">Milk fouling at <span class="hlt">direct</span> ohmic heating</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Direct</span> ohmic heating (Joules heating) is a technology to warm up the food using an electric energy where electric current is passed through a material which gets heated by virtue of its electrical resistance. Advantages over conventional indirect heating methods are speed and uniformity of heating. On the other side, the <span class="hlt">direct</span> ohmic heating of liquid foods has some problems,</p> <div class="credits"> <p class="dwt_author">J. Stancl; R. Zitny</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">477</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/49836737"> <span id="translatedtitle">Laser <span class="hlt">direct</span> writing of metal interconnects</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Laser <span class="hlt">direct</span> writing of metals offers the advantages of in-situ design and repair of IC's with a process that can be controlled and altered from chip to chip to meet the designer's needs. A summary of the laser <span class="hlt">direct</span> writing techniques for metal deposition -- photolytic, pyrolytic, and photo-thermal is presented with an emphasis on the advantages of each technique</p> <div class="credits"> <p class="dwt_author">T. Cacouris; R. R. Krchnavek; H. H. Gilgen; S. Kulick; J. Schoen</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">478</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1663705"> <span id="translatedtitle"><span class="hlt">Direct</span> kinematic solution of a Stewart platform</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Stewart platform is a fully parallel, six-degree-of-freedom manipulator mechanism. Although its inverse kinematics have been extensively studied, no solutions to the <span class="hlt">direct</span> position kinematics problem have been previously presented in the literature. A solution of the <span class="hlt">direct</span> kinematics problem of the case in which the six limbs form three concurrent pairs at either the base or the hand member</p> <div class="credits"> <p class="dwt_author">PRABJOT NANUA; KENNETH J. WALDRON; VASUDEVA MURTHY</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">479</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/57938613"> <span id="translatedtitle">A Reformulated <span class="hlt">Directional</span> Bias of Tourist Flow</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Conventional <span class="hlt">directional</span> bias is unable to identify the interactions and relationships between emitted tourist flows and attracted tourist flows, while arguably contradicting the actual emitting\\/attracting functions for any region, especially in systematic analysis. A newly coined FTR (Functional Tourism Region) based on a regional perspective and a new <span class="hlt">directional</span> bias derived from conceptual, geographical and technical contexts are proposed. This</p> <div class="credits"> <p class="dwt_author">Shien Zhong; Jie Zhang; Xiang Li</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">480</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/35004049"> <span id="translatedtitle"><span class="hlt">Direct</span> Selling in the West and East</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Not a lot is known about <span class="hlt">direct</span> selling and especially the newer forms of <span class="hlt">direct</span> selling, such as multi-level selling and Internet selling. What drives the effectiveness of these systems? The current study takes up one specific aspect of this question by comparing the effectiveness drivers from an Eastern country (China) and a Western country (Australia). Are these drivers different</p> <div class="credits"> <p class="dwt_author">Bill Merrilees; Dale Miller</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_23");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a 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