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1

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

Microsoft Academic Search

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

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

2009-01-01

2

Direct methanol fuel cell with extended reaction zone anode: PtRu and PtRuMo supported on graphite felt  

Microsoft Academic Search

Pressed graphite felt (thickness ?350?m) with electrodeposited PtRu (43gm?2, 1.4:1 atomic ratio) or PtRuMo (52gm?2, 1:1:0.3 atomic ratio) nanoparticle catalysts was investigated as an anode for direct methanol fuel cells. At temperatures above 333K the fuel cell performance of the PtRuMo catalyst was superior compared to PtRu. The power density was 2200Wm?2 with PtRuMo at 5500Am?2 and 353K while under

Alex Bauer; El?d L. Gyenge; Colin W. Oloman

2007-01-01

3

Synthesis of PtRu nanoparticles from the hydrosilylation reaction and application as catalyst for direct methanol fuel cell.  

PubMed

Nanosized Pt, PtRu, and Ru particles were prepared by a novel process, the hydrosilylation reaction. The hydrosilylation reaction is an effective method of preparation not only for Pt particles but also for other metal colloids, such as Ru. Vulcan XC-72 was selected as catalyst support for Pt, PtRu, and Ru colloids, and TEM investigations showed nanoscale particles and narrow size distribution for both supported and unsupported metals. All Pt and Pt-rich catalysts showed the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure, whereas the Ru and Ru-rich alloys were more typical of a hexagonal close-packed (hcp) structure. As evidenced by XPS, most Pt and Ru atoms in the nanoparticles were zerovalent, except a trace of oxidation-state metals. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results concluded that some alloy catalysts showed higher catalytic activities and better CO tolerance than the Pt-only catalyst; Pt56Ru44/C have displayed the best electrocatalytic performance among all carbon-supported catalysts. PMID:16853117

Huang, Junchao; Liu, Zhaolin; He, Chaobin; Gan, Leong Ming

2005-09-01

4

Electrochemical Oxidation of Hydrolyzed Poly Oxymethylene-dimethyl Ether by PtRu Catalysts on Nb-Doped SnO2-? Supports for Direct Oxidation Fuel Cells.  

PubMed

We synthesized Pt and PtRu catalysts supported on Nb-doped SnO2-? (Pt/Sn0.99Nb0.01O2-?, PtRu/Sn0.99Nb0.01O2-?) for direct oxidation fuel cells (DOFCs) using poly oxymethylene-dimethyl ether (POMMn, n = 2, 3) as a fuel. The onset potential for the oxidation of simulated fuels of POMMn (methanol-formaldehyde mixtures; n = 2, 3) for Pt/Sn0.99Nb0.01O2-? and PtRu/Sn0.99Nb0.01O2-? was less than 0.3 V vs RHE, which was much lower than those of two commercial catalysts (PtRu black and Pt2Ru3/carbon black). In particular, the onset potential of the oxidation reaction of simulated fuels of POMMn (n = 2, 3) for PtRu/Sn0.99Nb0.01O2-? sintered at 800 °C in nitrogen atmosphere was less than 0.1 V vs RHE and is thus considered to be a promising anode catalyst for DOFCs. The mass activity (MA) of PtRu/Sn0.99Nb0.01O2-? sintered at 800 °C was more than five times larger than those of the commercial catalysts in the measurement temperature range from 25 to 80 °C. Even though the MA for the methanol oxidation reaction was of the same order as those of the commercial catalysts, the MA for the formaldehyde oxidation reaction was more than five times larger than those of the commercial catalysts. Sn from the Sn0.99Nb0.01O2-? support was found to have diffused into the Pt catalyst during the sintering process. The Sn on the top surface of the Pt catalyst accelerated the oxidation of carbon monoxide by a bifunctional mechanism, similar to that for Pt-Ru catalysts. PMID:25415540

Kakinuma, Katsuyoshi; Kim, In-Tae; Senoo, Yuichi; Yano, Hiroshi; Watanabe, Masahiro; Uchida, Makoto

2014-12-24

5

Highly transparent and conductive Al-doped ZnO nanoparticulate thin films using direct write processing  

NASA Astrophysics Data System (ADS)

Solution processable Al-doped ZnO (AZO) thin films are attractive candidates for low cost transparent electrodes. We demonstrate here an optimized nanoparticulate ink for the fabrication of AZO thin films using scalable, low-cost direct write processing (ultrasonic spray deposition) in air at atmospheric pressure. The thin films were made via thermal processing of as-deposited films. AZO films deposited using the proposed nanoparticulate ink with further reducing in vacuum and rf plasma of forming gas exhibited optical transparency greater than 95% across the visible spectrum, and electrical resistivity of 0.5 ? cm and it drops down to 7.0 × 10-2 ? cm after illuminating with UV light, which is comparable to commercially available tin doped indium oxide colloidal coatings. Various structural analyses were performed to investigate the influence of ink chemistry, deposition parameters, and annealing temperatures on the structural, optical, and electrical characteristics of the spray deposited AZO thin films. Optical micrographs confirmed the presence of surface defects and cracks using the AZO NPs ink without any additives. After adding N-(2-Aminoethyl)-3-aminopropylmethyldimethoxy silane to the ink, AZO films exhibited an optical transparency which was virtually identical to that of the plain glass substrate.

Vunnam, S.; Ankireddy, K.; Kellar, J.; Cross, W.

2014-05-01

6

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

E-print Network

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

Kwak, Juhyoun

7

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

8

Comparative cytotoxicity assessments of some manufactured and anthropogenic nanoparticulate materials  

NASA Astrophysics Data System (ADS)

Due to increasing diversity of newly engineered nanoparticles, it is important to consider the hazards of these materials. Very little is known regarding the potential toxicity of relatively new nanomaterials. However, beginning with several historical accounts of nanomaterials applications---chrysotile asbestos and silver---it was assumed that these examples would provide some awareness and guidelines for future nanomaterial and nanotechnology applications, especially health effects. In this study in vitro assays were performed on a murine alveolar macrophage cell line (RAW 264.7), human alveolar macrophage cell line (THB-1), and human epithelial lung cell line (A549) to assess the comparative cytotoxicity of a wide range of manufactured (Ag, TiO2, Fe2O3, Al2O3, ZrO2, black carbon, two different types of multiwall structures and chrysotile asbestos as the toxicity standard) and anthropogenic nanoparticulates. There are several parameters of nanoparticulates that are considered to trigger an inflammatory response (particularly respiratory) or cause toxicity. These parameters include: particle size, shape, specific surface area, transition metals in particulates, and organic compounds. Therefore, a wide variety of manufactured and anthropogenic nanoparticulates having different morphologies, sizes, specific surface area and chemistries as noted were tested. To determine the nanoparticulates' size and morphology, they were characterized by transmission electron microscopy, where it was observed that the commercial multiwall carbon nanotube aggregate had an identical morphology to chrysotile asbestos and combustion-formed carbon nanotubes, i.e.; those that form from natural gas combustion. Light optical microscopy was used to determine cell morphology upon exposure to nanoparticulates as an indication of cell death. Also, the polycyclic aromatic hydrocarbon (PAH) content of the collected nanoparticulates was analyzed and correlated with cytotoxic responses. For toxicity evaluation, cytokine production, mitochondrial function (MTT assay), reactive oxygen species generation (ROS), were assessed after 48 and 336 hours under control and exposed conditions. A simple, direct-contact assay was developed to evaluate the toxicity of anthropogenic particulate matter (PM), without removing it from high volume filter collections and exposing collected PM by direct contact with the human epithelial (A549) cells in culture. The cell viability data revealed that the manufactured nanomaterials exhibit cytotoxic response for the murine alveolar and human macrophage cell line, but in particular to the human epithelial cell line. Assay results for the direct-contact of filter-collected carbonaceous nanoparticulate, showed toxicity for all PM, but with various natural gas combustion PM being the most toxic. Light optical microscopy examination of affected human epithelial cells confirmed quantitative results. These nanoparticulate soots also produced the most reactive oxygen species (ROS) on the A549 cell culture as well as along with the Fe2O3, MWCNT-N, and black carbon (BC). Comparison of polycyclic aromatic hydrocarbon (PAH) content and concentration for the carbonaceous PM showed no PAH correlation with relative cell viability after 48 h. In addition, there was no correlation of cytotoxic response with specific surface area in the manufactured nanoparticulate materials. In conclusion, the manufactured as well as the anthropogenic nanomaterials were observed to generate large amounts of ROS and cytokines. This study suggests that the mechanism of toxicity is likely due to the generation of reactive oxygen species (ROS). Also, the comparative assessments presented, should be viewed as a precaution when considering the inhalation of the corresponding nanoparticulate materials in concentrations approaching those identified to be dangerous for recognized pathogens such as silica, black carbon, and asbestos. Humans should avoid breathing these nanoparticulate materials, although there are anthropogenic nanoparticulate materials such as MWCNT agg

Soto, Karla Fabiola

9

Supporting Information Monodisperse PtRu Nanoalloy on Carbon  

E-print Network

Advanced Institute of Science and Technology, Daejeon, 305-701, Korea. E-mail: joontpark, and toluene. Catalyst Preparation: A suspension of colloidal PtRu nanoalloy (191.5 mg) and Vulcan carbon (191 (Fluka, 5.0 wt %) and 50 mL ultrapure water. The suspension of 30 µL was pipetted onto a working

Kwak, Juhyoun

10

Enhancement of ethanol oxidation at Pt and PtRu nanoparticles dispersed over hybrid zirconia-rhodium supports  

NASA Astrophysics Data System (ADS)

A catalytic material for electrooxidation of ethanol that utilizes PtRu nanoparticles dispersed over thin films of rhodium-free and rhodium-containing zirconia (ZrO2) supports is described here. The enhancement of electrocatalytic activity (particularly in the potential range as low as 0.25-0.5 V vs. RHE), that has been achieved by dispersing PtRu nanoparticles (loading, 100 ?g cm-2) over the hybrid Rh-ZrO2 support composed of nanostructured zirconia and metallic rhodium particles, is clearly evident from comparison of the respective voltammetric and chronoamperometric current densities recorded at room temperature (22 °C) in 0.5 mol dm-3 H2SO4 containing 0.5 mol dm-3 ethanol. Porous ZrO2 nanostructures, that provide a large population of hydroxyl groups in acidic medium in the vicinity of PtRu sites, are expected to facilitate the ruthenium-induced removal of passivating CO adsorbates from platinum, as is apparent from the diagnostic experiments with a small organic molecule such as methanol. Although Rh itself does not show directly any activity toward ethanol oxidation, the metal is expected to facilitate C-C bond splitting in C2H5OH. It has also been found during parallel voltammetric and chronoamperometric measurements that the hybrid Rh-ZrO2 support increases activity of the platinum component itself toward ethanol oxidation in the low potential range.

Rutkowska, Iwona A.; Koster, Margaretta D.; Blanchard, Gary J.; Kulesza, Pawel J.

2014-12-01

11

Structure and Chemical Composition of a Supported Pt-Ru Electrocatalyst for Methanol Oxidation  

Microsoft Academic Search

High resolution electron microscopy and X-ray microchemical analysis were used to characterize the composition, size, distribution, and morphology of Pt-Ru particles with nominal Pt:Ru ratios of 1:1 and 3:1, supported on carbon black. The particles are predominantly single nanocrystals with diameters in the order of 2.0 to 2.5 nm. Occasionally, twinned particles are also observed. All investigated particles represent solid

V. Radmilovic; H. A. Gasteiger; P. N. Jr. Ross

1995-01-01

12

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

13

PtRu nanofiber alloy counter electrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

With an aim of enhancing the light-to-electric power conversion efficiency of dye-sensitized solar cell (DSSC), here we synthesize PtRu nanofiber alloys using a low-temperature hydrothermal technique which are employed as counter electrodes (CEs) for DSSCs. Owing to the good electrical conduction and electrocatalysis, light-to-electric power conversion efficiencies of PtRu-based DSSCs have been elevated in comparison with that of Pt CE based DSSC. The DSSC employing PtRu3 alloy CE gives a power conversion efficiency of 6.80% in comparison with 6.17% from Pt-based DSSC. The reasonable conversion efficiency, simple preparation, and scalability demonstrate the potential use of PtRu alloys in efficient DSSCs.

Cai, Hongyuan; Tang, Qunwei; He, Benlin; Li, Pinjiang

2014-07-01

14

Extracellular stability of nanoparticulate drug carriers  

PubMed Central

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

Liu, Karen C.; Yeo, Yoon

2014-01-01

15

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

PubMed

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

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

2013-04-01

16

Nanoparticulate cellular patches for cell-mediated tumoritropic delivery.  

PubMed

The targeted delivery of therapeutics to tumors remains an important challenge in cancer nanomedicine. Attaching nanoparticles to cells that have tumoritropic migratory properties is a promising modality to address this challenge. Here we describe a technique to create nanoparticulate cellular patches that remain attached to the membrane of cells for up to 2 days. NeutrAvidin-coated nanoparticles were anchored on cells possessing biotinylated plasma membrane. Human bone marrow derived mesenchymal stem cells with nanoparticulate patches retained their inherent tumoritropic properties as shown using a tumor model in a 3D extracellular matrix. Additionally, human umbilical vein endothelial cells with nanoparticulate patches were able to retain their functional properties and form multicellular structures as rapidly as unmodified endothelial cells. These results provide a novel strategy to actively deliver nanostructures and therapeutics to tumors utilizing stem cells as carriers and also suggest that nanoparticulate cellular patches may have applications in tissue regeneration. PMID:20121215

Cheng, Hao; Kastrup, Christian J; Ramanathan, Renuka; Siegwart, Daniel J; Ma, Minglin; Bogatyrev, Said R; Xu, Qiaobing; Whitehead, Kathryn A; Langer, Robert; Anderson, Daniel G

2010-02-23

17

Preparation of Pt–Ru catalysts on Nafion(Na +)-bonded carbon layer using galvanostatic pulse electrodeposition for proton-exchange membrane fuel cell  

Microsoft Academic Search

Platinum–ruthenium (Pt–Ru) on a Nafion(Na+)-bonded carbon layer is fabricated by using galvanostatic pulse electrodeposition for high utilization of catalysts and cost reduction. The composition of the Pt–Ru electrode, which is controlled by varying the concentration of the Ru precursor, is determined by inductively coupled plasma-atomic emission spectroscopy and by electron probe microanalysis. The particle size of the electrodeposited Pt–Ru catalyst

Youngmi Ra; Jaeseung Lee; In Kim; Sungyool Bong; Hasuck Kim

2009-01-01

18

Temperature-dependent methanol electro-oxidation on well-characterized Pt-Ru alloys  

Microsoft Academic Search

The kinetics of methanol electro-oxidation on well-characterized Pt-Ru alloy surfaces were measured in sulfuric acid solution as a function of temperature. The alloy surfaces were prepared in ultrahigh vacuum with the surface composition determined by low energy ion scattering. It was found that the activity of Ru towards the dissociative adsorption of methanol is a strong function of temperature. This

Hubert A. Gasteiger; N. Markovic; P. N. Jr. Ross; E. J. Cairns

1994-01-01

19

PMo 12 -functionalized Graphene nanosheet-supported PtRu nanocatalysts for methanol electro-oxidation  

Microsoft Academic Search

Graphene nanosheets, synthesized by a modified Hummers method, have been functionalized by PMo12, and used as the supports of the PtRu nanoparticles. The electrocatalytic properties of the resultant nanocatalysts (PtRu\\/PMo12-Graphene) for methanol electro-oxidation have been evaluated by cyclic voltammetry and chronoamperometry. The micrograph\\u000a and the elemental composition have also been investigated by transmission electron microscopy and energy dispersive X-ray\\u000a spectroscopy.

Haiyong Li; Xiaohua Zhang; Haili Pang; Changting Huang; Jinhua Chen

2010-01-01

20

Highly Alloyed PtRu Nanoparticles Confined in Porous Carbon Structure as a Durable Electrocatalyst for Methanol Oxidation.  

PubMed

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

Yang, Chunzhen; Zhou, Ming; Gao, Liang

2014-11-12

21

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

22

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

PubMed Central

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

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

2014-01-01

23

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

24

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

2008-02-01

25

A CO-tolerant PtRu catalyst supported on thiol-functionalized carbon nanotubes for the methanol oxidation reaction  

NASA Astrophysics Data System (ADS)

PtRu nanoparticles (NPs) with enhanced methanol oxidation are prepared by a simple chemical reduction method using the thiol-functionalized carbon nanotubes (SH-CNTs) as support. Electrochemical measurements confirmed that the higher methanol oxidation is due to the excellent CO tolerance of PtRu NPs. From the comparison with the PtRu/COOH-CNTs catalyst, the experiment results demonstrate that excellent CO tolerance is originated from the strong interaction between Pt atoms and the -SH groups, which weakens CO adsorption and leads a higher methanol oxidation activity.

Guo, Lin; Chen, Siguo; Li, Li; Wei, Zidong

2014-02-01

26

Structure evolution of nanoparticulate Fe2O3.  

PubMed

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

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

2015-02-01

27

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

28

Nanotechnology in Biomaterials: Nanoparticulates as Drug Delivery Systems  

E-print Network

227 11 Nanotechnology in Biomaterials: Nanoparticulates as Drug Delivery Systems Birsen Demirbag Delivery Systems A drug delivery system (DDS) can be de ned as the system that achieves the administra the concentration, rate, time, and place of release of drugs in the body.1 The primary purpose of drug delivery

Hasýrcý, Vasýf

29

Surface modified nanoparticulate carrier constructs for oral mucosal vaccine delivery.  

PubMed

Mucosal administration of vaccines is one of the most popular approaches to induce desired immunity against various types of antigen and microbial in central as well as peripheral blood and in most external mucosal surfaces. The oral route is a preferred choice over parenteral route for this purpose mainly due to an ease of administration and therefore, for the possibility of covering large population for mass immunization. Different strategies of mucosal vaccination aimed to prevent colony formation and infection by pathogens and block its development. But a major concern with these vaccines is the degradation of protein components in stomach due to physiological conditions and gastric enzymes. Therefore, surface modified nanoparticles offer a better and stable alternative for efficient delivery and better activation of required immune responses. Natural and synthetic polymers are used to prepare nanoparticulate carrier systems for the development of oral mucosal vaccines. Amongst these, biodegradable polymers based nano-particulate carriers have been explored extensively for the development of delivery systems. Present review summarizes possible approaches and mechanisms for the systemic immunization by oral vaccines and critically discusses various polymers used, different strategies of surface modification to achieve targeting of antigen loaded nanoparticulate carrier at cellular level that are essentially required for a successful mucosal vaccination approach, and future prospects of nanoparticulate system as adjutants in oral mucosal vaccination. PMID:25007830

Mishra, Neeraj; Singh, Devendra; Sharma, Sandeep; Baldi, Ashish

2014-01-01

30

Nanoparticulate bioavailable iron minerals in icebergs and glaciers R. RAISWELL  

E-print Network

Nanoparticulate bioavailable iron minerals in icebergs and glaciers R. RAISWELL 1 , L. G. BENNING 1, Bristol University, Bristol BS8 1SS, UK ABSTRACT Ice-hosted sediments in glaciers and icebergs from by icebergs to the Southern Ocean is comparable to the flux of soluble, bioavailable Fe from aeolian dust

Benning, Liane G.

31

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.

32

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

Microsoft Academic Search

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

Suh Cem Pang; Wai Hwa Khoh; Suk Fun Chin

2010-01-01

33

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, Patrícia; Basso, Rafael; Santana, Maria Helena A

2013-01-01

34

Mechanisms of Tumor Vascular Priming by a Nanoparticulate Doxorubicin Formulation  

PubMed Central

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

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

2013-01-01

35

PtRu catalysts supported on heteropolyacid and chitosan functionalized carbon nanotubes for methanol oxidation reaction of fuel cells.  

PubMed

A simple self-assembly approach has been developed to functionalize carbon nanotubes (CNTs) with chitosan (CS) and heteropolyacids (HPAs) of phosphomolybdic acid (H(3)PMo(12)O(40), HPMo) and phosphotungstic acid (H(3)PW(12)O(40), HPW). The non-covalent functionalization method, which introduces homogenous surface functional groups with no detrimental effect on graphene structures of CNTs, can be carried out at room temperature without the use of corrosive acids. The PtRu nanoparticles supported on HPAs-CS-CNTs have a uniform distribution and much smaller size as compared to those of the PtRu nanoparticles supported on conventional acid treated CNTs (PtRu/AO-CNTs). The onset and peak potentials for CO(ad) oxidation on PtRu/HPAs-CS-CNTs catalysts are more negative than those on PtRu/AO-CNTs, indicating that HPAs facilitate the electro-oxidation of CO. The PtRu/HPMo-CS-CNTs catalyst has a higher electrocatalytic activity for methanol oxidation and higher tolerance toward CO poisoning than PtRu/HPW-CS-CNTs. The better electrocatalytic enhancement of HPMo on the PtRu/HPAs-CS-CNTs catalyst is most likely related to the fact that molybdenum-containing HPAs such as HPMo have more labile terminal oxygen to provide additional active oxygen sites while accelerating the CO and methanol oxidation in a similar way to that of Ru in the PtRu binary alloy system. PMID:21842101

Cui, Zhiming; Li, Chang Ming; Jiang, San Ping

2011-09-28

36

Dispersion of nanoparticulate suspensions using self-assembled surfactant aggregates  

NASA Astrophysics Data System (ADS)

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

Singh, Pankaj Kumar

37

Nanoparticulate Coatings with Efficient Up-Conversion Properties.  

PubMed

Nanoparticulate films with high up-conversion emission (UC) properties were prepared by spray-deposition of nanometer-sized YVO4:Yb,Er particles. The optical properties of YVO4:Yb,Er were optimized upon annealing before the film deposition in order to get the highest possible UC signal in the considered type of system. Thanks to a simple model and some time-resolved spectroscopic investigations, the contribution of the scattering to the UC signal could be separated from the intrinsic properties (crystallinity, surface defects) of the material. The films obtained by this technique present the advantages of having both high UC and good transparency. PMID:25409538

Dantelle, Geraldine; Calderón-Villajos, Rocío; Zaldo, Carlos; Cascales, Concepción; Gacoin, Thierry

2014-12-01

38

Kinetic analysis of nanoparticulate polyelectrolyte complex interactions with endothelial cells.  

PubMed

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. PMID:17560645

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

2007-09-01

39

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-shell–type lipid-PLGA hybrids, cell-PLGA hybrids, receptor-specific ligand-PLGA conjugates, and theranostics. Each PLGA-based nanoparticulate dosage form has specific features that distinguish it from other nanoparticulate systems. This review focuses on fundamental concepts and practices that are used in the development of various functional nanoparticulate dosage forms. We describe how the attributes of these functional nanoparticulate forms might contribute to achievement of desired therapeutic effects that are not attainable using conventional therapies. Functional PLGA-based nanoparticulate systems are expected to deliver chemotherapeutic, diagnostic, and imaging agents in a highly selective and effective manner. PMID:23459088

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

2013-01-01

40

Nanoparticulate carrier system: a novel treatment approach for hyperlipidemia.  

PubMed

Abstract Hyperlipidemia is a prevailing risk factor that leads to development and progression of atherosclerosis and consequently cardiovascular diseases. Several antihyperlipidemic drugs are having various disadvantages such as low water solubility and poor bioavailabilty due to presystemic gastrointestinal clearance. Thus, there is a considerable need for the development of efficient delivery methods and carriers. This review focuses on the importance and role of various nanoparticulate systems as carrier for antihyperlipidemic drugs in the treatment of hyperlipidemia. Some nanoparticle technology-based products are approved by FDA for effective treatment of hyperlipidemia, namely Tricor® by Abbott Laboratories (Chicago, IL, USA) and Triglide® by Skye Pharma (London, UK). Efforts to address each of these issues are going on, and should remain the focus on the future studies and look forward to many more clinical products in the future. PMID:24904976

Sharma, Kritika; Kumar, Kulyash; Mishra, Neeraj

2014-06-01

41

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

42

Sol-Gel Process for Making Pt-Ru Fuel-Cell Catalysts  

NASA Technical Reports Server (NTRS)

A sol-gel process has been developed as a superior alternative to a prior process for making platinum-ruthenium alloy catalysts for electro-oxidation of methanol in fuel cells. The starting materials in the prior process are chloride salts of platinum and ruthenium. The process involves multiple steps, is time-consuming, and yields a Pt-Ru product that has relatively low specific surface area and contains some chloride residue. Low specific surface area translates to incomplete utilization of the catalytic activity that might otherwise be available, while chloride residue further reduces catalytic activity ("poisons" the catalyst). In contrast, the sol-gel process involves fewer steps and less time, does not leave chloride residue, and yields a product of greater specific area and, hence, greater catalytic activity. In this sol-gel process (see figure), the starting materials are platinum(II) acetylacetonate [Pt(C5H7O2)2, also denoted Pt-acac] and ruthenium(III) acetylacetonate [Ru(C5H7O2)3, also denoted Ru-acac]. First, Pt-acac and Ru-acac are dissolved in acetone at the desired concentrations (typically, 0.00338 moles of each salt per 100 mL of acetone) at a temperature of 50 C. A solution of 25 percent tetramethylammonium hydroxide [(CH3)4NOH, also denoted TMAH] in methanol is added to the Pt-acac/Ruacac/ acetone solution to act as a high-molecular-weight hydrolyzing agent. The addition of the TMAH counteracts the undesired tendency of Pt-acac and Ru-acac to precipitate as separate phases during the subsequent evaporation of the solvent, thereby helping to yield a desired homogeneous amorphous gel. The solution is stirred for 10 minutes, then the solvent is evaporated until the solution becomes viscous, eventually transforming into a gel. The viscous gel is dried in air at a temperature of 170 C for about 10 hours. The dried gel is crushed to make a powder that is the immediate precursor of the final catalytic product. The precursor powder is converted to the final product in a controlled-atmosphere heat treatment. Desirably, the final product is a phase-pure (Pt phase only) Pt-Ru powder with a high specific surface area. The conditions of the controlled- atmosphere heat are critical for obtaining the aforementioned desired properties. A typical heat treatment that yields best results for a catalytic alloy of equimolar amounts of Pt and Ru consists of at least two cycles of heating to a temperature of 300 C and holding at 300 C for several hours, all carried out in an atmosphere of 1 percent O2 and 99 percent N2. The resulting powder consists of crystallites with typical linear dimensions of <10 nm. Tests have shown that the powder is highly effective in catalyzing the electro-oxidation of methanol.

Narayanan, Sekharipuram; Valdez, Thomas; Kumta, Prashant; Kim, Y.

2005-01-01

43

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

Microsoft Academic Search

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

Kevin Letchford; Helen Burt

2007-01-01

44

Nanoparticulate carriers (NPC) for oral pharmaceutics and nutraceutics.  

PubMed

The introduction of nanoparticulate carriers (NPC) in the pharmaceutic and nutraceutic fields has changed the definitions of disease management and treatment, diagnosis, as well as the supply food chain in the agri-food sector. NPC composed of synthetic polymers, proteins or polysaccharides gather interesting properties to be used for oral administration of pharmaceutics and nutraceutics. Oral administration remains the most convenient way of delivering drugs (e.g. peptides, proteins and nucleic acids) since these suffer similar metabolic pathways as food supply. Recent advances in biotechnology have produced highly potent new molecules however with low oral bioavailability. A suitable and promising approach to overcome their sensitivity to chemical and enzymatic hydrolysis as well as the poor cellular uptake, would be their entrapment within suitable gastrointestinal (GI) resistant NPC. Increasing attention has been paid to the potential use of NPC for peptides, proteins, antioxidants (carotenoids, omega fatty acids, coenzyme Q10), vitamins, probiotics, for oral administration. This review focuses on the most important materials to produce NPC for oral administration, and the most recent achievements in the production techniques and bioactives successfully delivered by these means. PMID:20225647

Lopes, C M; Martins-Lopes, P; Souto, E B

2010-02-01

45

Dynamics of discontinuous coating and drying of nanoparticulate films.  

SciTech Connect

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

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

2010-09-01

46

Microstructures and Nanostructures for Environmental Carbon Nanotubes and Nanoparticulate Soots  

PubMed Central

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

Murr, L. E.

2008-01-01

47

Structurally inhomogeneous nanoparticulate catalysts in cobalt-catalyzed carbon nanotube growth  

NASA Astrophysics Data System (ADS)

The structure of nanoparticulate catalysts involved in cobalt-catalyzed chemical vapor deposition growth of carbon nanotubes (CNTs) was investigated by in situ environmental transmission electron microscopy (ETEM). In contrast to previous studies, the analyses of ETEM images showed that the nanoparticulate catalysts were structurally inhomogeneous during CNT growth in the source gas of acetylene at a rate of pressure increase of about 3 Pa/h and at 550 °C. The lattice fringes observed in the nanoparticulate catalysts can be accounted for by not a single crystalline structure but by several possible pairs of structures including pure Co and cobalt carbides. The inhomogeneous structures were unstable with time. The possible origin of the inhomogeneous structures is discussed.

Kohigashi, Y.; Yoshida, H.; Homma, Y.; Takeda, S.

2014-08-01

48

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. PMID:16823077

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

49

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 (0.010–0.020g), which contain noble metals (NMs) in the range between 0 and 30%

Silvera Scaccia; Barbara Goszczynska

2004-01-01

50

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

51

Methylation of Mercury by Bacteria Exposed to Dissolved, Nanoparticulate, and Microparticulate Mercuric Sulfides  

E-print Network

Methylation of Mercury by Bacteria Exposed to Dissolved, Nanoparticulate, and Microparticulate bacteria that methylate Hg(II). In sediment porewater, Hg(II) associates with sulfides and natural organic intermediates of heterogeneous mineral precipitation. Here, we exposed two strains of sulfate-reducing bacteria

52

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

PubMed Central

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

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

2013-01-01

53

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

54

New Catalysts for Direct Methanol Oxidation Fuel Cells  

SciTech Connect

A new class of efficient electrocatalytic materials based on platinum - metal oxide systems has been synthetized and characterized by several techniques. Best activity was found with NiWO{sub 4}-, CoWO{sub 4}-, and RuO{sub 2}- sr¡pported platinum catalysts. A very similar activity at room temperature was observed with the electrodes prepared with the catalyst obtained from International Fuel Cells Inc. for the same Pt loading. Surprisingly, the two tungstates per se show a small activity for methanol oxidation without any Pt loading. Synthesis of NiWO{sub 4} and CoWO{sub 4} were carried out by solid-state reactions. FTIR spectroscopy shows that the tungstates contain a certain amount of physically adsorbed water even after heating samples at 200{degrees}C. A direct relationship between the activity for methanol oxidation and the amount of adsorbed water on those oxides has been found. The Ru(0001) single crystal shows a very small activity for CO adsorption and oxidation, in contrast to the behavior of polycrystalline Ru. In situ extended x-ray absorption fine structure spectroscopy (EXAFS) and x-ray absorption near edge spectroscopy (XANES) showed that the OH adsorption on Ru in the Pt-Ru alloy appears to be the limiting step in methanol oxidation. This does not occur for Pt-RuO{SUB 2} electrocatalyst, which explains its advantages over the Pt-Ru alloys. The IFCC electrocatalyst has the properties of the Pt-Ru alloy.

Adzic, Radoslav

1998-08-01

55

Novel Anode Catalyst for Direct Methanol Fuel Cells  

PubMed Central

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

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

2014-01-01

56

Nanoparticulate silver increases uric acid and allantoin excretion in rats, as identified by metabolomics.  

PubMed

Metabolomic investigation of rat urine was employed to identify mammalian metabolites affected by ionic or nanoparticulate silver. Female and male Wistar rats were administered silver nanoparticles (2.25, 4.5 or 9.0 mg kg(-1) body weight per day) or ionic silver (silver acetate, 9.0 mg silver kg(-1) bw per day) by oral gavage for 28 days. On day 18, urine was collected for 24 h and subjected to metabolomics with high performance liquid chromatography-quadropole time-of-flight mass spectrometry (HPLC-QTOF-MS)-based separation and detection. Principal component analysis was subsequently applied to the data. Metabolomic differences in urine composition were found in female rats but not in male rats. Several metabolites were identified by the use of elemental composition calculated from the exact mass combined with searches in the Human Metabolome Database.The metabolite identities were eventually verified by co-chromatography with authentic standards. Differences were found in uric acid and its degradation product, allantoin. Administration of nanoparticulate silver increased both metabolites, whereas ionic silver only increased allantoin. In conclusion, metabolomic investigation of rat urine showed that increased levels of uric acid and allantoin were associated with exposure to nanoparticulate silver. PMID:22610381

Hadrup, Niels; Lam, Henrik R; Loeschner, Katrin; Mortensen, Alicja; Larsen, Erik H; Frandsen, Henrik

2012-11-01

57

Water-based nanoparticulate solar cells using a diketopyrrolopyrrole donor polymer.  

PubMed

Organic photovoltaic devices with either bulk heterojunction (BHJ) or nanoparticulate (NP) active layers have been prepared from a 1?:?2 blend of (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene}) (PDPP-TNT) and the fullerene acceptor, ([6,6]-phenyl C71-butyric acid methyl ester) (PC70BM). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been used to investigate the morphology of the active layers of the two approaches. Mild thermal treatment of the NP film is required to promote initial joining of the NPs in order for the devices to function, however the NP structure is retained. Consequently, whereas gross phase segregation of the active layer occurs in the BHJ device spin cast from chloroform, the nanoparticulate approach retains control of the material domain sizes on the length scale of exciton diffusion in the materials. As a result, NP devices are found to generate more than twice the current density of BHJ devices and have a substantially greater overall efficiency. The use of aqueous nanoparticulate dispersions offers a promising approach to control the donor acceptor morphology on the nanoscale with the benefit of environmentally-friendly, solution-based fabrication. PMID:24382591

Vaughan, Ben; Williams, Evan L; Holmes, Natalie P; Sonar, Prashant; Dodabalapur, Ananth; Dastoor, Paul C; Belcher, Warwick J

2014-02-14

58

Stabilization of Nanoparticulate HgS by Thiols and Humic Substances During HgS Precipitation  

NASA Astrophysics Data System (ADS)

In the aquatic environment mercury has a strong affinity for reduced sulfur-containing ligands such as inorganic sulfides and thiolate functional groups in natural organic matter (NOM). Complexation of aqueous Hg(II) is particularly important because coordination to inorganic sulfide and humic compounds governs Hg(II) speciation (and subsequent bioavailability and mobility) in contaminated water and sediment. The purpose of this study was to explore the potential for NOM-coated HgS nanoparticles in the aquatic environment. HgS precipitation experiments were conducted in the presence of natural organic acids that are prevalent in surface water and sediment porewater. Dynamic light scattering was used to the monitor the size of HgS particles precipitating over time. The results indicated that humic substances decreased growth rates of precipitating HgS particles and stabilized particles with aggregate diameters smaller than 0.2 ?m for at least 8 hours. Thiol-containing low molecular weight acids such as cysteine and thioglycolate also decreased growth of HgS particles whereas the hydroxyl-containing acids (serine and glycolate) did not affect particle growth rates. As the humic and thiol concentration increased in solution, growth rates of HgS particles decreased. Growth rates of the aggregates increased in solutions with greater ionic strength. Nanoparticles of HgS would be possible in aquatic environments where HgS precipitation is possible. We conducted equilibrium speciation calculations to determine HgS(s) saturation indices under conditions typical for sediment porewater. The calculations indicated that the metacinnabar saturation index was 1 to 3 orders of magnitude above or below saturation, depending on Hg-(bi)sulfide and Hg-NOM binding constants, which vary by orders of magnitude. These insights suggest that HgS nanoparticles may exist in surface waters and porewater of contaminated sediments as a result of kinetically-hindered mineralization reactions. Hg(II) uptake rates by methylating organisms may be governed by rate-limited mineralization reactions, rather than equilibrium Hg(II) speciation in porewater. However, further studies are needed to directly quantify the bioavailability of nanoparticulate Hg to microbes.

Hsu-Kim, H.; Deonarine, A.

2008-12-01

59

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. Aricò; P. Cretì; E. Modica; M. Pham-Thi; J. P. Ganne

2001-01-01

60

Direct methanol fuel cells with reticulated vitreous carbon, uncompressed graphite felt and Ti mesh anodes  

Microsoft Academic Search

Reticulated vitreous carbon (RVC, 39 pores per cm), uncompressed graphite felt (UGF) and Ti mesh were investigated as 3-D\\u000a anode catalyst supports for direct liquid methanol fuel cells with the aim of improving the catalyst mass specific activity.\\u000a Mesoporous Pt–Ru layers composed of nano-particle agglomerates were electrodeposited on the 3-D substrates using a micellar\\u000a deposition media composed of Triton X-100,

Tommy T. Cheng; El?d L. Gyenge

2008-01-01

61

Carbon nano-fiber interlayer that provides high catalyst utilization in direct methanol fuel cell  

Microsoft Academic Search

The introduction of a carbon nano-fiber (CNF) interlayer to the interface between the carbon paper and the catalyst layer was investigated for providing a highly active catalyst layer with PtRu nano-particles on it for the direct methanol fuel cell (DMFC) anode. A precipitation method was used for applying the CNF layer and the catalyst layer. The effects of the loadings

Masataka Okada; Yuri Konta; Nobuyoshi Nakagawa

2008-01-01

62

Dynamics of nanoparticules detected at 1 AU by S/WAVES onboard STEREO spacecraft  

NASA Astrophysics Data System (ADS)

In order to interpret in detail the S/WAVES data on the interplanetary nanodust discovered by STEREO at 1 AU [Meyer-Vernet et al., 2009], we study the dynamics of nanoparticles in the inner interplanetary medium as well as the distribution of their velocities and directions of arrival, with a model based on [Czechowski and Mann, 2012]. We deduce the charges released by their impacts on the STEREO spacecraft at 1 AU and their dependence on the position of the spacecraft on their orbits. The model studies nanoparticles of size equal or smaller than about 70 nm, assumed to be created via collisional fragmentation of dust grains of larger size moving on keplerian orbits, and sublimation of dust, meteoroids and comets. The nanoparticles are released near the Sun with initial velocities close to keplerian, and mainly subjected to the Lorentz force calculated with a simple solar wind model. A part of the nanoparticles is accelerated to high speeds of the order of 300 km/s, thereby providing impact charges between 10(-14) and 10(-11) Cb [Belheouane, 2014] which enable them to be detected by S/WAVES, whereas another part is trapped within about 0.2 AU from the Sun. We discuss how the fluxes and direction of arrival at 1 AU are expected to change in function of the solar cycle. These results enable us to interpret in detail the STEREO/WAVES observations [Zaslavsky et al., 2012]; [Pantellini et al., 2013]; [Le Chat et al., 2013]. Belheouane, S. (2014). Nanoparticules dans le vent solaire, observations spatiales et theorie. PhD thesis, Pierre and Marie Curie University UPMC. Czechowski, A. and Mann, I. (2012). Nanodust Dynamics in Interplanetary Space, chapter Nanodust Dynamics in Interplanetary Space. Springer Berlin Heidelberg. Le Chat, G., Zaslavsky, A., Meyer-Vernet, N., Issautier, K., Belheouane, S., Pantellini, F., Maksimovic, M., Zouganelis, I., Bale, S., and Kasper, J. (2013). Interplanetary Nanodust Detection by the Solar Terrestrial Relations Observatory/WAVES Low Frequency Receiver. Solar Physics, 286(2):549-559. Meyer-Vernet, N., Maksimovic, M., Czechowski, A., Mann, I., Zouganelis, I., Goetz, K., Kaiser, M., Cyr, O. S., Bougeret, J.-L., and Bale, S. (2009). Dust Detection by the Wave Instrument on STEREO : Nanoparticles Picked up by the Solar Wind? Solar Phys, 256:463-474. Pantellini, F., Le Chat, G., Belheouane, S., Meyer-Vernet, N., and Zaslavsky, A. (2013). On the detection of nano dust using spacecraft based boom antennas. Solar Wind 13: Proceedings of the Thirteenth International Solar Wind Conference, 1539:414-417. Zaslavsky, A., Meyer-Vernet, N., Mann, I., Czechowski, A., Issautier, K., Le Chat, G., Pantellini, F., Goetz, K., Maksimovic, M., Bale, S. D., and Kasper, J. K. (2012). Interplanetary dust detection by radio antennas: Mass calibration and fluxes measured by STEREO/WAVES. J. Geophys. Res., 117.

Belheouane, Soraya; Issautier, Karine; Meyer-Vernet, Nicole; Le Chat, Gaétan; Czechowski, Andrzej; Zaslavsky, Arnaud; Zouganelis, Yannis; Mann, Ingrid

63

Structure and electrical properties of nanoparticulate tungsten oxide prepared by microwave plasma synthesis  

NASA Astrophysics Data System (ADS)

Nanoparticulate WO3 films were prepared using microwave plasma synthesis and studied with respect to the electrical conductivity in dependence of ambient conditions. The WO3 films with a monoclinic structure were made from cluster-assembled nanoparticles (diameter 3 nm) by means of dispersion and spin-coating. Above 100 °C a thermally activated decrease of the electrical resistance due to oxygen vacancy donors is found. A reversible increase of the electrical resistance R due to oxygen uptake is observed. The decrease of R in response to reducing H2S in the ppm range is studied in dependence of temperature and pre-annealing conditions.

Sagmeister, M.; Postl, M.; Brossmann, U.; List, E. J. W.; Klug, A.; Letofsky-Papst, I.; Szabó, D. V.; Würschum, R.

2011-08-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

65

Sweating liquid micro-marbles: dropwise condensation on hydrophobic nanoparticulate materials.  

PubMed

Liquid marbles have opened up several potential applications including biochemical batch reaction engineering and gas sensing. To be successful candidates in these applications, the ability to prepare liquid marbles of controlled sizes and in a continuous process is crucial. This has been the missing link in the science leading to these applications. In the current study, we present a remarkably simple process driven by condensation on a nanoparticulate matrix to continuously produce liquid marbles whose mean size can be controlled in the range of diameters from 3 to 1000 ?m, while the distribution width is also controllable independently. We experimentally demonstrate the physics involved in this condensation-driven marble formation process using two fluids-glycerol and ethylene glycol-which span an order of magnitude in viscosity. Hydrophobic fumed silica nanoparticulate material is used as the encapsulating medium owing to its intertwined agglomerate nature. We show that the primary mechanism causing the formation of liquid marbles is droplet nucleation followed by growth driven by condensation. Drop coalescence in dense droplet ensembles is the secondary mechanism, which attempts to destroy the distribution width controllability. From a physics perspective, it will be demonstrated that strong coalescence dominated growth gives rise to a hitherto unreported, significantly higher rate of growth. PMID:22994499

Bhosale, Prasad S; Panchagnula, Mahesh V

2012-10-23

66

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. 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

2013-11-01

67

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. PMID:21151975

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

2010-01-01

68

Exchange bias beyond the superparamagnetic blocking temperature of the antiferromagnet in a Ni-NiO nanoparticulate system  

SciTech Connect

We report magnetic and exchange bias studies on Ni-NiO nanoparticulate systems synthesized by a two-step process, namely, chemical reduction of a Ni salt followed by air annealing of the dried precipitate in the temperature range 400–550?°C. Size of Ni and NiO crystallites as estimated from X–ray diffraction line broadening ranges between 10.5–13.5?nm and 2.3–4?nm, respectively. The magneto-thermal plots (M-T) of these bi-magnetic samples show a well developed peak in the vicinity of 130?K. This has been identified as the superparamagnetic blocking temperature “T{sub B}” of NiO. Interestingly, all samples exhibit exchange bias even above their respective NiO blocking temperatures, right up to 300?K, the maximum temperature of measurement. This is in contrast to previous reports since exchange bias requires the antiferromagnetic NiO to have a stable direction of its moment in order to pin the ferromagnet (Ni) magnetization, whereas such stability is unlikely above T{sub B} since the NiO is superparamagnetic, its moment flipping under thermal activation. Our observation is elucidated by taking into account the core-shell morphology of the Ni-NiO nanoparticles whereby clustering of some of these nanoparticles connects their NiO shells to form extended continuous regions of NiO, which because of their large size remain blocked at T?>?T{sub B}, with thermally stable spins capable of pinning the Ni cores and giving rise to exchange bias. The investigated samples may thus be envisaged as being constituted of both isolated core-shell Ni-NiO nanoparticles as well as clustered ones, with T{sub B} denoting the blocking temperature of the NiO shell of the isolated particles.

Roy, Aparna, E-mail: aparna.roy@ua.pt, E-mail: aparnaroy15@gmail.com; Ferreira, J. M. F. [Department of Materials and Ceramics Engineering and CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); De Toro, J. A.; Muniz, P.; Riveiro, J. M. [Departamento de Fisica Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Amaral, V. S. [Department of Physics and CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

2014-02-21

69

Exchange bias beyond the superparamagnetic blocking temperature of the antiferromagnet in a Ni-NiO nanoparticulate system  

NASA Astrophysics Data System (ADS)

We report magnetic and exchange bias studies on Ni-NiO nanoparticulate systems synthesized by a two-step process, namely, chemical reduction of a Ni salt followed by air annealing of the dried precipitate in the temperature range 400-550 °C. Size of Ni and NiO crystallites as estimated from X-ray diffraction line broadening ranges between 10.5-13.5 nm and 2.3-4 nm, respectively. The magneto-thermal plots (M-T) of these bi-magnetic samples show a well developed peak in the vicinity of 130 K. This has been identified as the superparamagnetic blocking temperature "TB" of NiO. Interestingly, all samples exhibit exchange bias even above their respective NiO blocking temperatures, right up to 300 K, the maximum temperature of measurement. This is in contrast to previous reports since exchange bias requires the antiferromagnetic NiO to have a stable direction of its moment in order to pin the ferromagnet (Ni) magnetization, whereas such stability is unlikely above TB since the NiO is superparamagnetic, its moment flipping under thermal activation. Our observation is elucidated by taking into account the core-shell morphology of the Ni-NiO nanoparticles whereby clustering of some of these nanoparticles connects their NiO shells to form extended continuous regions of NiO, which because of their large size remain blocked at T > TB, with thermally stable spins capable of pinning the Ni cores and giving rise to exchange bias. The investigated samples may thus be envisaged as being constituted of both isolated core-shell Ni-NiO nanoparticles as well as clustered ones, with TB denoting the blocking temperature of the NiO shell of the isolated particles.

Roy, Aparna; De Toro, J. A.; Amaral, V. S.; Muniz, P.; Riveiro, J. M.; Ferreira, J. M. F.

2014-02-01

70

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

2012-05-01

71

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

72

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

PubMed

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

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

2014-08-19

73

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

PubMed

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

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

2014-12-01

74

Active radar guides missile to its target: receptor-based targeted treatment of hepatocellular carcinoma by nanoparticulate systems.  

PubMed

Patients with hepatocellular carcinoma (HCC) usually present at advanced stages and do not benefit from surgical resection, so drug therapy should deserve a prominent place in unresectable HCC treatment. But chemotherapy agents, such as doxorubicin, cisplatin, and paclitaxel, frequently encounter important problems such as low specificity and non-selective biodistribution. Recently, the development of nanotechnology led to significant breakthroughs to overcome these problems. Decorating the surfaces of nanoparticulate-based drug carriers with homing devices has demonstrated its potential in concentrating chemotherapy agents specifically to HCC cells. In this paper, we reviewed the current status of active targeting strategies for nanoparticulate systems based on various receptors such as asialoglycoprotein receptor, transferrin receptor, epidermal growth factor receptor, folate receptor, integrin, and CD44, which are abundantly expressed on the surfaces of hepatocytes or liver cancer cells. Furthermore, we pointed out their merits and defects and provided theoretical references for further research. PMID:25424700

Yan, Jing-Jun; Liao, Jia-Zhi; Lin, Ju-Sheng; He, Xing-Xing

2015-01-01

75

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

E-print Network

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

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

2013-01-01

76

Zn sorption mechanisms onto sheathed Leptothrix discophora and the impact of the nanoparticulate biogenic Mn oxide coating.  

PubMed

Zinc sorption on sheathed Leptothrix discophora bacterium, the isolated extracellular polymeric substances (EPS) sheath, and Mn oxide-coated bacteria was investigated with macroscopic and spectroscopic techniques. Complexation with L. discophora was dominated by the outer membrane phosphoryl groups of the phospholipid bilayer while sorption to isolated EPS was dominated by carboxyl groups. Precipitation of nanoparticulate Mn oxide coatings on the cell surface increased site capacity by over twenty times with significant increase in metal sorption. XAS analysis of Zn sorption in the coated system showed Mn oxide phase contributions of 18 to 43% through mononuclear inner-sphere complexes. The coordination environments in coprecipitation samples were identical to those of sorption samples, indicating that, even in coprecipitation, Zn is not incorporated into the Mn oxide structure. Rather, through enzymatic oxidation by L. discophora, Mn(II) is oxidized and precipitated onto the biofilm providing a large surface for metal sequestration. The nanoparticulate Mn oxide coating exhibited significant microporosity (75%) suggesting contributions from intraparticle diffusion. Transient studies conducted over 7 months revealed a 170% increase in Zn loading. However, the intraparticle diffusivity of 10(-19) cm(2) s(-1) is two orders of magnitude smaller than that for abiotic Mn oxide which we attribute to morphological changes such as reduced pore sizes in the nanoparticulate oxide. Our results demonstrate that the cell-bound Mn oxide particles can sorb significant amounts of Zn over long periods of time representing an important surface for sequestration of metal contaminants. PMID:19268965

Boonfueng, Thipnakarin; Axe, Lisa; Yee, Nathan; Hahn, Dittmar; Ndiba, Peter K

2009-05-15

77

Zn Sorption Mechanisms onto Sheathed Leptothrix Discophora and the Impact of the Nanoparticulate Biogenic Mn Oxide Coating  

SciTech Connect

Zinc sorption on sheathed Leptothrix discophora bacterium, the isolated extracellular polymeric substances (EPS) sheath, and Mn oxide-coated bacteria was investigated with macroscopic and spectroscopic techniques. Complexation with L. discophora was dominated by the outer membrane phosphoryl groups of the phospholipid bilayer while sorption to isolated EPS was dominated by carboxyl groups. Precipitation of nanoparticulate Mn oxide coatings on the cell surface increased site capacity by over twenty times with significant increase in metal sorption. XAS analysis of Zn sorption in the coated system showed Mn oxide phase contributions of 18 to 43% through mononuclear inner-sphere complexes. The coordination environments in coprecipitation samples were identical to those of sorption samples, indicating that, even in coprecipitation, Zn is not incorporated into the Mn oxide structure. Rather, through enzymatic oxidation by L. discophora, Mn(II) is oxidized and precipitated onto the biofilm providing a large surface for metal sequestration. The nanoparticulate Mn oxide coating exhibited significant microporosity (75%) suggesting contributions from intraparticle diffusion. Transient studies conducted over 7 months revealed a 170% increase in Zn loading. However, the intraparticle diffusivity of 10{sup -19} cm{sup 2} s{sup -1} is two orders of magnitude smaller than that for abiotic Mn oxide which we attribute to morphological changes such as reduced pore sizes in the nanoparticulate oxide. Our results demonstrate that the cell-bound Mn oxide particles can sorb significant amounts of Zn over long periods of time representing an important surface for sequestration of metal contaminants.

Boonfueng, T.; Axe, L; Yee, N; Hahn, D; Ndiba, P

2009-01-01

78

Low-Pt-Content Anode Catalyst for Direct Methanol Fuel Cells  

NASA Technical Reports Server (NTRS)

Combinatorial experiments have led to the discovery that a nanophase alloy of Pt, Ru, Ni, and Zr is effective as an anode catalyst material for direct methanol fuel cells. This discovery has practical significance in that the electronic current densities achievable by use of this alloy are comparable or larger than those obtained by use of prior Pt/Ru catalyst alloys containing greater amounts of Pt. Heretofore, the high cost of Pt has impeded the commercialization of direct methanol fuel cells. By making it possible to obtain a given level of performance at reduced Pt content (and, hence, lower cost), the discovery may lead to reduction of the economic impediment to commercialization.

Narayanan, Sekharipuram; Whitacre, Jay

2008-01-01

79

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

PubMed

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 (0.010-0.020g), which contain noble metals (NMs) in the range between 0 and 30% in combination among them or with other non-NMs, is obtained under mild conditions using both concentrated HCl and HCl+HNO(3) (1+1 (v/v)) mixture to boiling for 30min in an open vessel. Carbon is separated from the solution by filtering it. Under optimized conditions of the flame, the poor sensitivity of platinum is enhanced 50-fold in presence of 1% (mV(-1)) ascorbic acid, whereas the analytical signal of ruthenium increased by the presence of co-existing platinum. Any kind of interference is observed on the analytical signal of molybdenum. Recovery test obtained by analyzing commercial powder catalysts ranged from 99 to 101%. The precision, expressed as relative standard deviation of five measurements, is better than 1%. Electrode catalysts, made by using the carbon-supported platinum-based powder catalysts, have been analyzed for the metal loadings onto the electrode by GFAAS after dissolution under the same conditions used for the powder catalysts. The precision, expressed as relative standard deviation of three measurements, is better than 2%. PMID:18969501

Scaccia, Silvera; Goszczynska, Barbara

2004-06-17

80

Effects of nitrogen and carbon monoxide concentrations on performance of proton exchange membrane fuel cells with Pt-Ru anodic catalyst  

NASA Astrophysics Data System (ADS)

The reformate gas is one of the commonest solutions to the problem of fuel supply for proton exchange membrane fuel cell systems. Thus, it is important to understand the behaviors of a fuel cell using reformate gases. In this work, effects of nitrogen and carbon monoxide concentrations on unsteady characteristics of a proton exchange membrane fuel cell with the Pt-Ru anodic catalyst are investigated experimentally. Simulated reformate gases with hydrogen, nitrogen and carbon monoxide are employed as the fuel. The experimental data show that a larger dilution effect of nitrogen is noted for cases with lower hydrogen stoichiometric ratios. Furthermore, increasing the carbon monoxide concentration reduces the cell performance because the elevated carbon monoxide adsorption rate results in a severer poison effect. The voltage fluctuating phenomenon is observed at high CO ppm and is due to a periodical change of coverage on the catalyst surface. Meanwhile, it is verified that the voltage fluctuation is accompanied with a periodical change of the anode outlet carbon monoxide concentration. Furthermore, the fluctuating phenomena of voltage and the anode outlet carbon monoxide concentration are more easily triggered in diluted hydrogen than in non-diluted hydrogen.

Chen, Chen-Yu; Lai, Wei-Hsiang; Yan, Wei-Mon; Chen, Chun-Chi; Hsu, Sui-Wei

2013-12-01

81

Selective electrochemical detection of dopamine in a microfluidic channel on carbon nanoparticulate electrodes.  

PubMed

There is a continuous need for the construction of detection systems in microfluidic devices. In particular, electrochemical detection allows the separation of signals from the analyte and interfering substances in the potential domain. Here, a simple microfluidic device for the sensitive and selective determination of dopamine in the presence of interfering substances was constructed and tested. It employs a carbon nanoparticulate electrode allowing the separation of voltammetric signals of dopamine and common interfering substances (ascorbic acid and acetaminophen) both in quiescent conditions and in flow due to the electrocatalytic effect. These voltammograms were also successfully simulated. The limit of detection of dopamine detected by square wave voltammetry in 1 mM solutions of interfering substances in phosphate buffered saline is about 100 nM. In human serum a clear voltammetric signal could be seen for a 200 nM solution, sufficient to detect dopamine in the cerebral fluid. Flow injection analysis allows a decrease in the limit of detection down to 3.5 nM. PMID:24757708

Rozniecka, Ewa; Jonsson-Niedziolka, Martin; Celebanska, Anna; Niedziolka-Jonsson, Joanna; Opallo, Marcin

2014-06-01

82

Effect of nanoparticulate bioactive glass particles on bioactivity and cytocompatibility of poly(3-hydroxybutyrate) composites  

PubMed Central

This work investigated the effect of adding nanoparticulate (29 nm) bioactive glass particles on the bioactivity, degradation and in vitro cytocompatibility of poly(3-hydroxybutyrate) (P(3HB)) composites/nano-sized bioactive glass (n-BG). Two different concentrations (10 and 20 wt %) of nanoscale bioactive glass particles of 45S5 Bioglass composition were used to prepare composite films. Several techniques (Raman spectroscopy, scanning electron microscopy, atomic force microscopy, energy dispersive X-ray) were used to monitor their surface and bioreactivity over a 45-day period of immersion in simulated body fluid (SBF). All results suggested the P(3HB)/n-BG composites to be highly bioactive, confirmed by the formation of hydroxyapatite on material surfaces upon immersion in SBF. The weight loss and water uptake were found to increase on increasing bioactive glass content. Cytocompatibility study (cell proliferation, cell attachment, alkaline phosphatase activity and osteocalcin production) using human MG-63 osteoblast-like cells in osteogenic and non-osteogenic medium showed that the composite substrates are suitable for cell attachment, proliferation and differentiation. PMID:19640877

Misra, Superb K.; Ansari, Tahera; Mohn, Dirk; Valappil, Sabeel P.; Brunner, Tobias J.; Stark, Wendelin J.; Roy, Ipsita; Knowles, Jonathan C.; Sibbons, Paul D.; Jones, Eugenia Valsami; Boccaccini, Aldo R.; Salih, Vehid

2010-01-01

83

Developing micro-/nanoparticulate drug delivery systems using “design of experiments”  

PubMed Central

Of late, micro and nanoparticluate drug delivery systems have been gaining immense importance primarily attributed to their improved drug release controlling and targeting efficiencies. Also, the small particle size and desirable surface charge associated with these delivery systems render them suitable for specific applications like lymphatic uptake, pulmonary uptake, tumor targeting, brain targeting, etc. For decades, micro and nanoparticulate systems have been prepared by the conventional “trial and error” approach of changing One Variable at a Time (OVAT). Using this methodology, the solution of a specific problematic formulation characteristic can certainly be achieved, but attainment of the true optimal composition is never guaranteed. Thus, the present manuscript provides an updated account of the systematic approach “Design of Experiments (DoE)” as applicable to formulation development of microparticles and nanostructured systems. Besides providing a bird's eye view of the various experimental designs and optimization techniques employed for DoE optimization of such systems, the present manuscript also presents a copilation of the major micro/nano-structuctred systems optimized through DoE till date. In a nutshell, the article will act both as a ready reckoner of DoE optimization of micro/nano drug delivery systems and a catalyst in providing an impetus to young pharmaceutical “nano & micro” researchers to venture into the rewarding field of systematic DoE optimization. PMID:23071925

Singh, Bhupinder; Bhatowa, Rahul; Tripathi, Chandra Bhushan; Kapil, Rishi

2011-01-01

84

Effects of ZnO nanoparticulate addition on the properties of PMNT ceramics  

PubMed Central

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

2012-01-01

85

Nonagonistic Dectin-1 ligand transforms CpG into a multitask nanoparticulate TLR9 agonist.  

PubMed

CpG DNA, a ligand for Toll-like receptor 9 (TLR9), has been one of the most promising immunotherapeutic agents. Although there are several types of potent humanized CpG oligodeoxynucleotide (ODN), developing "all-in-one" CpG ODNs activating both B cells and plasmacytoid dendritic cells forming a stable nanoparticle without aggregation has not been successful. In this study, we generated a novel nanoparticulate K CpG ODN (K3) wrapped by the nonagonistic Dectin-1 ligand schizophyllan (SPG), K3-SPG. In sharp contrast to K3 alone, K3-SPG stimulates human peripheral blood mononuclear cells to produce a large amount of both type I and type II IFN, targeting the same endosome where IFN-inducing D CpG ODN resides without losing its K-type activity. K3-SPG thus became a potent adjuvant for induction of both humoral and cellular immune responses, particularly CTL induction, to coadministered protein antigens without conjugation. Such potent adjuvant activity of K3-SPG is attributed to its nature of being a nanoparticle rather than targeting Dectin-1 by SPG, accumulating and activating antigen-bearing macrophages and dendritic cells in the draining lymph node. K3-SPG acting as an influenza vaccine adjuvant was demonstrated in vivo in both murine and nonhuman primate models. Taken together, K3-SPG may be useful for immunotherapeutic applications that require type I and type II IFN as well as CTL induction. PMID:24516163

Kobiyama, Kouji; Aoshi, Taiki; Narita, Hirotaka; Kuroda, Etsushi; Hayashi, Masayuki; Tetsutani, Kohhei; Koyama, Shohei; Mochizuki, Shinichi; Sakurai, Kazuo; Katakai, Yuko; Yasutomi, Yasuhiro; Saijo, Shinobu; Iwakura, Yoichiro; Akira, Shizuo; Coban, Cevayir; Ishii, Ken J

2014-02-25

86

Cytotoxic Responses and Potential Respiratory Health Effects of Carbon and Carbonaceous Nanoparticulates in the Paso del Norte Airshed Environment  

PubMed Central

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.

2008-01-01

87

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

PubMed

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

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

2012-07-01

88

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

PubMed

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

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

2014-10-01

89

Microparticulated and nanoparticulated zirconium oxide added to calcium silicate cement: Evaluation of physicochemical and biological properties.  

PubMed

The physicochemical and biological properties of calcium silicate-based cement (CS) associated to microparticulated (micro) or nanoparticulated (nano) zirconium oxide (ZrO2 ) were compared with CS and bismuth oxide (BO) with CS. The pH, release of calcium ions, radiopacity, setting time, and compression strength of the materials were evaluated. The tissue reaction promoted by these materials in the subcutaneous was also investigated by morphological, immunohistochemical, and quantitative analyses. For this purpose, polyethylene tubes filled with materials were implanted into rat subcutaneous. After 7, 15, 30, and 60 days, the tubes surrounded by capsules were fixed and embedded in paraffin. In the H&E-stained sections, the number of inflammatory cells (ICs) in the capsule was obtained. Moreover, detection of interleukin-6 (IL-6) by immunohistochemistry and number of IL-6 immunolabeled cells were carried out. von Kossa method was also performed. The differences among the groups were subjected to Tukey test (p???0.05). The solutions containing the materials presented an alkaline pH and released calcium ions. The addition of radiopacifiers increased setting time and radiopacity of CS. A higher compressive strength in the CS?+?ZrO2 (micro and nano) was found compared with CS?+?BO. The number of IC and IL-6 positive cells in the materials with ZrO2 was significantly reduced in comparison with CS?+?BO. von Kossa-positive structures were observed adjacent to implanted materials. The ZrO2 associated to the CS provides satisfactory physicochemical properties and better biological response than BO. Thus, ZrO2 may be a good alternative for use as radiopacifying agent in substitution to BO. PMID:24497271

Silva, Guilherme F; Bosso, Roberta; Ferino, Rafael V; Tanomaru-Filho, Mário; Bernardi, Maria I B; Guerreiro-Tanomaru, Juliane M; Cerri, Paulo S

2014-12-01

90

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

PubMed

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

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

2014-05-01

91

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

PubMed Central

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

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

2013-01-01

92

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

NASA Astrophysics Data System (ADS)

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

Khurana, Jatin

93

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

PubMed

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

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

2004-07-01

94

Porphyrin-sensitized nanoparticulate TiO2 as the photoanode of a hybrid photoelectrochemical biofuel cell.  

PubMed

Porphyrin-sensitized nanoparticulate TiO(2) on conducting glass has been investigated as a photoanode material for a new cell that converts light energy into electricity. The cell is a hybrid of a dye-sensitized nanoparticulate semiconductor photoelectrochemical solar cell, and a biofuel cell that oxidizes glucose. Porphyrin molecules excited by light inject electrons into the photoanode, from where they enter the external circuit. The resulting porphyrin radical cations are reduced by NADH in aqueous buffer, ultimately regenerating the photoanode and producing NAD(+). Glucose dehydrogenase oxidizes glucose, and in the process recycles NAD(+) back to NADH. The photoanode is coupled with a suitable cathode to make a functioning cell (Hg/Hg(2)SO(4) was employed for evaluation purposes). The cell produces 1.1 V at open circuit and has a fill factor of 0.61. These values are both significantly higher than those for a previously reported cell of a similar type based on an SnO(2) electrode. PMID:15350115

Brune, Alicia; Jeong, Goojin; Liddell, Paul A; Sotomura, Tadashi; Moore, Thomas A; Moore, Ana L; Gust, Devens

2004-09-14

95

Nanoparticulate flurbiprofen reduces amyloid-?42 generation in an in vitro blood–brain barrier model  

PubMed Central

Introduction The amyloid-?42 (A?42) peptide plays a crucial role in the pathogenesis of Alzheimer’s disease (AD), the most common neurodegenerative disorder affecting the elderly. Over the past years, several approaches and compounds developed for the treatment of AD have failed in clinical studies, likely in part due to their low penetration of the blood–brain barrier (BBB). Since nanotechnology-based strategies offer new possibilities for the delivery of drugs to the brain, this technique is studied intensively for the treatment of AD and other neurological disorders. Methods The A?42 lowering drug flurbiprofen was embedded in polylactide (PLA) nanoparticles by emulsification-diffusion technique and their potential as drug carriers in an in vitro BBB model was examined. First, the cytotoxic potential of the PLA-flurbiprofen nanoparticles on endothelial cells and the cellular binding and uptake by endothelial cells was studied. Furthermore, the biological activity of the nanoparticulate flurbiprofen on ?-secretase modulation as well as its in vitro release was examined. Furthermore, the protein corona of the nanoparticles was studied as well as their ability to transport flurbiprofen across an in vitro BBB model. Results PLA-flurbiprofen nanoparticles were endocytosed by endothelial cells and neither affected the vitality nor barrier function of the endothelial cell monolayer. The exposure of the PLA-flurbiprofen nanoparticles to human plasma occurred in a rapid protein corona formation, resulting in their decoration with bioactive proteins, including apolipoprotein E. Furthermore, luminally administered PLA-flurbiprofen nanoparticles in contrast to free flurbiprofen were able to modulate ?-secretase activity by selectively decreasing A?42 levels in the abluminal compartment of the BBB model. Conclusions In this study, we were able to show that flurbiprofen can be transported by PLA nanoparticles across an in vitro BBB model and most importantly, the transported flurbiprofen modulated ?-secretase activity by selectively decreasing A?42 levels. These results demonstrate that the modification of drugs via embedding in nanoparticles is a promising tool to facilitate drug delivery to the brain, which enables future development for the treatment of neurodegenerative disorders like AD. PMID:24280275

2013-01-01

96

Impact of dissolved silica on arsenite removal by nano-particulate FeS and FeS-coated sand.  

PubMed

This work evaluated the inhibitory effect of dissolved silica on arsenite adsorption to nanoparticulate FeS (NP-FeS) or mackinawite and FeS-coated sand (CS-FeS) sorbents. Arsenite retention by the NP-FeS solid was not affected by dissolved silicate over a wide range in pH, in contrast to the known inhibitory effect of dissolved silica on As(III) uptake by Fe-(hydr)oxide systems. However, some inhibition was observed in CS-FeS system at pH 9. This latter result is attributed to the co-existence of both FeS and small amounts of Fe-(hydr)oxide phases on the sand surface. Given the ubiquitous presence of dissolved Si in groundwater, FeS-based sorbents may have an advantage for As retention compared to those based on Fe-(hydr)oxides in reducing subsurface environments. PMID:23538091

Han, Young-Soo; Demond, Avery H; Hayes, Kim F

2013-07-01

97

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

PubMed

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

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

2013-10-01

98

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

PubMed

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

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

2015-02-01

99

Degradation of nanoparticulate-coated and uncoated sulfide-based cathodoluminescent phosphors.  

SciTech Connect

Changes in the cathodoluminescent (CL) brightness and in the surface chemistry of nanoparticulate SiO{sub 2}-coated and uncoated ZnS:Ag, Cl powder phosphor have been investigated using a PHI 545 scanning Auger electron spectrometer (AES), an Oriel optical spectrometer and a JEOL 6400 scanning electron microscope (SEM). The data were collected in a stainless steel UHV chamber with residual gas pressures between 1 x 10{sup -8} and 1 x 10{sup -6} Torr as measured by a Dycor LC residual gas analyzer (RGA). The primary electron current density was 272 {micro}A/cm{sup 2}, while the primary beam energy was varied bwteen 2 and 5 keV. In the presence of a 2keV primary electron beam in 1 x 10{sup -6} Torr of water for both the SiO{sub 2}-coated and the uncoated cases, the amounts of C and S on the surface decreased, that of O increased and the CL intensity decreased with electron dose. This surface chemistry change lead to the development of a surface dead layer and is explained by the electron beam stimulated surface chemical reaction model (ESSCR). The penetration range of the impinging low energy primary electrons is on the order of 10-100 nm creating a reaction region very close to the surface. The ESSCR takes this into account postulating that primary and secondary electrons dissociate physisorbed molecules to form reactive atomic species. These atomic species remove surface S as volatile SO{sub x} or H{sub 2}S. In the case of an oxidizing ambient (i.e. high partial pressure of water), a non-luminescent ZnO layer is formed. this oxide layer has been measured to be on the order of 3-30 nm. In the case where the vacuum of 1 x 10{sup -8} Torr was dominated by hydrogen and had a low water content, there was a small increase in the S signal, no rise in the O Auger signal, but the CL intensity still decreased. This is explained by the ESSCR whereby H removes S as H{sub 2}S leaving elemental Zn, which evaporates due to a high vapor pressure. In the case of ZnS:Ag,Cl coated with SiO{sub 2}, morphological changes were observed on the surface after extended electron beam exposure. Erosion of ZnS occurs more dramatically at an accelerating voltage of 5kV even at the same current density. Uncoated ZnS:Ag,Cl phosphors exhibited similar surface chemical changes to that of SiO{sub 2}-coated ZnS:Ag,Cl but did not degrade to the same extent. Also, no change in the surface morphology was observed. These SEM images as well as reaction rate data suggest that these nanometer sized SiO{sub 2} particles acted as a catalyst for decomposition of the ZnS especially in a reducing ambient (i.e. high hydrogen partial pressure). In order to reduce CL degradation of these and other phosphors, protective coatings were pulse laser deposited onto the phosphor surface. The effectiveness of these coatings was dependent upon both the thickness and the uniformity. Thicknesses of these coatings ranged from 1-5 nm and were uniform as determined using profilometry and TEM.

Abrams, Billie Lynn; Bang, Jungsik S. (University of Florida, Gainesville, FL); Thomes, William Joseph, Jr.; Holloway, Paul H. (University of Florida, Gainesville, FL)

2003-07-01

100

Thin Film Catalyst Layers for Direct Methanol Fuel Cells  

NASA Technical Reports Server (NTRS)

One of the primary obstacles to the widespread use of the direct methanol fuel cell (DMFC) is the high cost of the catalyst. Therefore, reducing the catalyst loading well below the current level of 8-12 mg/cm 2 would be important to commercialization. The current methods for preparation of catalyst layers consisting of catalyst, ionomer and sometimes a hydrophobic additive are applied by either painting, spraying, decal transfer or screen printing processes. Sputter deposition is a coating technique widely used in manufacturing and therefore particularly attractive. In this study we have begun to explore sputtering as a method for catalyst deposition. Present experiments focus on Pt-Ru catalyst layers for the anode.

Witham, C. K.; Chun, W.; Ruiz, R.; Valdez, T. I.; Narayanan, S. R.

2000-01-01

101

Chemically tuned anode with tailored aqueous hydrocarbon binder for direct methanol fuel cells.  

PubMed

An anode for direct methanol fuel cells was chemically tuned by tailoring an aqueous hydrocarbon catalyst (SPI-BT) binder instead of using a conventional perfluorinated sulfonic acid ionomer (PFSI). SPI-BT designed in triethylamine salt form showed lower proton conductivity than PFSI, but it was stable in the catalyst ink forming the aqueous colloids. The aqueous colloidal particle size of SPI-BT was much smaller than that of PFSI. The small SPI-BT colloidal particles contributed to forming small catalyst agglomerates and simultaneously reducing their pore volume. Consequently, the high filling level of binders in the pores, where Pt-Ru catalysts are mainly located on the wall and physically interconnected, resulted in increased electrochemical active surface area of the anode, leading to high catalyst utilization. In addition, the chemical affinity between the SPI-BT binder and the membrane material derived from their similar chemical structure induced a stable interface on the membrane-electrode assembly (MEA) and showed low electric resistance. Upon adding SPI-BT, the synergistic effect of high catalyst utilization, improved mass transfer behavior to Pt-Ru catalyst, and low interfacial resistance of MEA became greater than the influence of reduced proton conductivity in the electrochemical performance of single cells. The electrochemical performance of MEAs with SPI-BT anode was enhanced to almost the same degree or somewhat higher than that with PFSI at 90 degrees C. PMID:19485372

Lee, Chang Hyun; Lee, So Young; Lee, Young Moo; McGrath, James E

2009-07-21

102

X-ray absorption and photoelectron spectroscopic study of the association of As(III) with nanoparticulate FeS and FeS-coated sand.  

PubMed

Iron sulfide (FeS) has been demonstrated to have a high removal capacity for arsenic (As) in reducing environments. However, FeS may be present as a coating, rather than in nanoparticulate form, in both natural and engineered systems. Frequently, the removal capacity of coatings may be different than that of nanoparticulates in batch systems. To assess the differences in removal mechanisms between nanoparticulate FeS and FeS present as a coating, the solid phase products from the reaction of As(III) with FeS-coated sand and with suspensions of nanoparticulate (NP) FeS were determined using x-ray absorption spectroscopy and x-ray photoelectron spectroscopy. In reaction with NP FeS at pH 5, As(III) was reduced to As(II) to form realgar (AsS), while at pH 9, As(III) adsorbed as an As(III) thioarsenite species. In contrast, in the FeS-coated sand system, As(III) formed the solid phase orpiment (As(2)S(3)) at pH 5, but adsorbed as an As(III) arsenite species at pH 9. These different solid reaction products are attributed to differences in FeS concentration and the resultant redox (pe) differences in the FeS-coated sand system versus suspensions of NP FeS. These results point to the importance of accounting for differences in concentration and redox when making inferences for coatings based on batch suspension studies. PMID:21911241

Han, Young-Soo; Jeong, Hoon Y; Demond, Avery H; Hayes, Kim F

2011-11-01

103

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

PubMed

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

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

2014-06-25

104

Effect of Ni precursor solution concentration on the magnetic properties and exchange bias of Ni-NiO nanoparticulate systems  

NASA Astrophysics Data System (ADS)

We report on a comparative study of the exchange bias effect and magnetic properties of Ni-NiO nanoparticulate systems synthesized by the chemical reduction of NiCl2 solution of two different molar concentrations—1 M (high) and 0.05 M (low)—followed by annealing of the dried precipitate in the temperature range 400-600 °C in air. Interestingly, the samples derived from the low molarity solution have higher Ni content and larger crystallite size than those prepared from their high molarity counterparts. These molarity dependent features subsequently modulate the magnitude of the exchange bias field in the samples, which is found to be absent or small in the 0.05 M series, but of moderate value in the 1 M samples. The different physical attributes of the particles derived from different concentrations of Ni-precursor solution are explained by invoking different nucleation kinetics and supersaturation degrees surrounding the viable growing nucleus. Furthermore, an observed increase of exchange bias with increasing annealing temperature, in contrast to the reported agglomeration of particles on annealing and subsequent reduction in bias magnitude, has been explained in correlation to the Ni-NiO interface density.

Roy, Aparna; De Toro, J. A.; Amaral, V. S.; Marques, D. P.; Ferreira, J. M. F.

2014-09-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

106

Micro-CT Based Experimental Liver Imaging Using a Nanoparticulate Contrast Agent: A Longitudinal Study in Mice  

PubMed Central

Background Micro-CT imaging of liver disease in mice relies on high soft tissue contrast to detect small lesions like liver metastases. Purpose of this study was to characterize the localization and time course of contrast enhancement of a nanoparticular alkaline earth metal-based contrast agent (VISCOVER ExiTron nano) developed for small animal liver CT imaging. Methodology ExiTron nano 6000 and ExiTron nano 12000, formulated for liver/spleen imaging and angiography, respectively, were intravenously injected in C57BL/6J-mice. The distribution and time course of contrast enhancement were analysed by repeated micro-CT up to 6 months. Finally, mice developing liver metastases after intrasplenic injection of colon carcinoma cells underwent longitudinal micro-CT imaging after a single injection of ExiTron nano. Principal Findings After a single injection of ExiTron nano the contrast of liver and spleen peaked after 4–8 hours, lasted up to several months and was tolerated well by all mice. In addition, strong contrast enhancement of abdominal and mediastinal lymph nodes and the adrenal glands was observed. Within the first two hours after injection, particularly ExiTron nano 12000 provided pronounced contrast for imaging of vascular structures. ExiTron nano facilitated detection of liver metastases and provided sufficient contrast for longitudinal observation of tumor development over weeks. Conclusions The nanoparticulate contrast agents ExiTron nano 6000 and 12000 provide strong contrast of the liver, spleen, lymph nodes and adrenal glands up to weeks, hereby allowing longitudinal monitoring of pathological processes of these organs in small animals, with ExiTron nano 12000 being particularly optimized for angiography due to its very high initial vessel contrast. PMID:21984939

Boll, Hanne; Nittka, Stefanie; Doyon, Fabian; Neumaier, Michael; Marx, Alexander; Kramer, Martin; Groden, Christoph; Brockmann, Marc A.

2011-01-01

107

Chemodynamics of soft nanoparticulate complexes: Cu(II) and Ni(II) complexes with fulvic acids and aquatic humic acids.  

PubMed

The dynamics of metal complexation by small humic substances (fulvic acid and aquatic humic acid, collectively denoted as “fulvic-like substance”, FS) are explored within the framework of concepts recently developed for soft nanoparticulate complexants. From a comprehensive collection of published equilibrium and dissociation rate constants for CuFS and NiFS complexes, the association rate constant, ka, is determined as a function of the degree of complexing site occupation, ?. From this large data set, it is shown for the first time that ka is independent of ?. This result has important consequences for finding the nature of the rate limiting step in the association process. The influence of electric effects on the rate of the association process is described, namely (i) the accelerating effect of the negatively charged electrostatic field of FS on the diffusion of metal ions toward it, and (ii) the extent to which metal ions electrostatically accumulate in the counterionic atmosphere of FS. These processes are discussed qualitatively in relation to the derived values of ka. For slowly dehydrating metal ions such as Ni(H2O)6 2+ (dehydration rate constant, kw), ka is expected to derive straight from kw. In contrast, for rapidly dehydrating metal ions such as Cu(H2O)6 2+, transport limitations and electric effects involved in the formation of the precursor outer-sphere associate appear to be important overall rate-limiting factors. This is of great significance for understanding the chemodynamics of humic complexes in the sense that inner-sphere complex formation would not always be the (sole) rate limiting step. PMID:22934531

Town, Raewyn M; van Leeuwen, Herman P; Buffle, Jacques

2012-10-01

108

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 150–250 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. PMID:23007664

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

2012-01-01

109

High pinning performance of YBa2Cu3O7?x films added with Y2O3 nanoparticulate defects  

NASA Astrophysics Data System (ADS)

We report the epitaxial growth and superconducting properties of Y2O3-added YBa2Cu3Ox (YBCO) films grown on SrTiO3-buffered MgO substrates by pulsed-laser deposition using surface-modified YBCO targets. Areas of Y2O3 sectors on the YBCO target were increased to 5.44% and 9.22% of the total YBCO pellet in order to find a correlation between the Y2O3 content, morphology, and the pinning properties of YBCO + Y2O3 mixed films. The maximum global pinning forces, FP, at 77 K were 14.3 GN m?3 and 1.15 GN m?3 for the Y2O3 5.44A% and 9.22A%, respectively. The 5.44A% Y2O3-added sample presents a very high value of pinning force at 77 K, approaching the value obtained in YBCO films with added BaZrO3 nanorods, but with less depression in the superconducting critical temperature, Tc. In accordance with scanning transmission electron microscopy (STEM) observations, both films present nanoparticulate Y2O3 dispersed in a YBCO matrix where Y2Ba4Cu8O16 (Y248) intergrowths were also observed. Consistent with the strong pinning theory, the size and distribution of randomly dispersed Y2O3 particles are optimal for the flux pinning of a 5.44A% Y2O3-YBCO film, while in the case of a 9.22A% film, the YBCO matrix is degraded by jam-packed Y248 intergrowth, which leads to a comparatively poor pinning performance. We further used the single-vortex dynamics model to account for vortex pinning in the samples. The 5.44A% Y2O3-YBCO film result shows good agreement with the model fit up to 4 T of the applied magnetic field.

Mele, Paolo; Guzman, Roger; Gazquez, Jaume; Puig, Teresa; Obradors, Xavier; Saini, Shrikant; Yoshida, Yutaka; Mukaida, Masashi; Ichinose, Ataru; Matsumoto, Kaname; Idries Adam, Malik

2015-02-01

110

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

PubMed

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 150?250 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 µM), CUR SLN (2.5 µM) and free SFN (5 µM) 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. PMID:23007664

Sutaria, Dhruvitkumar; Grandhi, Balagangadhar Karthik; Thakkar, Arvind; Wang, Jeffrey; Prabhu, Sunil

2012-12-01

111

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. PMID:20519360

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

112

Comparative Toxicity of Nanoparticulate CuO and ZnO to Soil Bacterial Communities  

PubMed Central

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

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

2012-01-01

113

Selective electrocatalysts toward a prototype of the membraneless direct methanol fuel cell  

NASA Astrophysics Data System (ADS)

Mastery over the structure of nanomaterials enables control of their properties to enhance their performance for a given application. Herein we demonstrate the design and fabrication of Pt-based nanomaterials with enhanced catalytic activity and superior selectivity toward the reactions in direct methanol fuel cells (DMFCs) upon the deep understanding of the mechanisms of these electrochemical reactions. In particular, the ternary Au@Ag2S-Pt nanocomposites display superior methanol oxidation reaction (MOR) selectivity due to the electronic coupling effect among different domains of the nanocomposites, while the cage-bell structured Pt-Ru nanoparticles exhibit excellent methanol tolerance for oxygen reduction reaction (ORR) at the cathode because of the differential diffusion of methanol and oxygen in the porous Ru shell of the cage-bell nanoparticles. The good catalytic selectivity of these Pt-based nanomaterials via structural construction enables a DMFC to be built without a proton exchange membrane between the fuel electrode and the oxygen electrode.

Feng, Yan; Yang, Jinhua; Liu, Hui; Ye, Feng; Yang, Jun

2014-01-01

114

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

115

Transmembrane diffusion of gemcitabine by a nanoparticulate squalenoyl prodrug: an original drug delivery pathway.  

PubMed

We have designed an amphiphilic prodrug of gemcitabine (dFdC) by its covalent coupling to a derivative of squalene, a natural lipid. The resulting bioconjugate self-assembled spontaneously in water as nanoparticles that displayed a promising in vivo anticancer activity. The aim of the present study was to provide further insight into the in vitro subcellular localization and on the metabolization pathway of the prodrug. Cells treated with radiolabelled squalenoyl gemcitabine (SQdFdC) were studied by differential detergent permeation, and microautography coupled to fluorescent immunolabeling and confocal microscopy. This revealed that the bioconjugate accumulated within cellular membranes, especially in those of the endoplasmic reticulum. Radio-chromatography analysis proved that SQdFdC delivered dFdC directly in the cell cytoplasm. Mass spectrometry studies confirmed that gemcitabine was then either converted into its biologically active triphosphate metabolite or exported from the cells through membrane transporters. To our knowledge, this is the first description of such an intracellular drug delivery pathway. In vitro cytotoxicity assays revealed that SQdFdC was more active than dFdC on a transporter-deficient human resistant leukemia model, which was explained by the subcellular distribution of the drugs and their metabolites. The squalenoylation drug delivery strategy might, therefore, dramatically improve the efficacy of gemcitabine on transporter-deficient resistant cancer in the clinical context. PMID:20691740

Bildstein, L; Dubernet, C; Marsaud, V; Chacun, H; Nicolas, V; Gueutin, C; Sarasin, A; Bénech, H; Lepêtre-Mouelhi, S; Desmaële, D; Couvreur, P

2010-10-15

116

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

117

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

PubMed

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

Leggett, Graham J

2011-03-22

118

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

119

Performance of a passive direct ethanol fuel cell  

NASA Astrophysics Data System (ADS)

Ethanol emerges as an attractive fuel since it is less toxic and has higher energy density than methanol and can be produced from biomass. Direct ethanol fuel cells (DEFCs) appear as a good choice for producing sustainable energy for portable applications. However, they are still far from attaining acceptable levels of power output, since their performance is affected by the slow electrochemical ethanol oxidation and water and ethanol crossover. In the present work, an experimental study on the performance of a passive DEFC is described. Tailored MEAs (membrane electrode assembly) with different catalyst loadings, anode diffusion layers and membranes were tested in order to select optimal working conditions at high ethanol concentrations and low ethanol crossover. The performance increased with an increase of membrane and anode diffusion layer thicknesses and anode catalyst loading. A maximum power density of 1.33 mW cm-2, was obtained using a Nafion 117 membrane, 4 mg cm-2 of Pt-Ru and 2 mg cm-2 of Pt on the anode and cathode catalyst layers, ELAT as anode diffusion layer, carbon cloth as cathode diffusion layer and an ethanol concentration of 2 M. As far as the authors are aware this is the first work reporting an experimental optimization of passive DEFCs.

Pereira, J. P.; Falcão, D. S.; Oliveira, V. B.; Pinto, A. M. F. R.

2014-06-01

120

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. PMID:24092972

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

2013-01-01

121

Nanoparticulate Mn3O4/VGCF composite conversion-anode material with extraordinarily high capacity and excellent rate capability for lithium ion batteries.  

PubMed

In this work, highly conductive vapor grown carbon fiber (VGCF) was applied as an electrically conductive agent for facile synthesis of a nanoparticulate Mn3O4/VGCF composite material. This material exhibits super high specific capacity and excellent rate capability as a conversion-anode for lithium ion batteries. Rate performance test result demonstrates that at the discharge/charge current density of 0.2 A g(-1) a reversible capacity of ca. 950 mAh g(-1) is delivered, and when the current rate is increased to a high current density of 5 A g(-1), a reversible capacity of ca. 390 mAh g(-1) is retained. Cyclic performance examination conducted at the current density of 0.5 A g(-1) reveals that in the initial 20 cycles the reversible capacity decreases gradually from 855 to 747 mAh g(-1). However, since then, it increases gradually with cycle number increasing, and after 200 cycles an extraordinarily high reversible capacity of 1391 mAh g(-1) is achieved. PMID:25247688

Ma, Feng; Yuan, Anbao; Xu, Jiaqiang

2014-10-22

122

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

123

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  

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

124

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

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

2013-11-01

125

Direct alcohol fuel cells: Increasing platinum performance by modification with sp-group metals  

NASA Astrophysics Data System (ADS)

By using sp group metals as modifiers, the catalytic properties of Pt can be improved toward alcohols oxidation. In this work we report the performance increase of direct alcohol fuel cells (DAFC) fuelled with ethanol or 2-propanol with platinum based anode electrodes modified with Bi and Sb adatoms. For example, by simply adding Sb to the Pt/C based anode ink during membrane electrode assembly fabrication of a direct ethanol fuel cell (DEFC) its performance is improved three-fold, with more than 100 mV increase in the open circuit potential. For the fuel cell fuelled with 2-propanol high power densities are obtained at very high potentials with these catalyst materials suggesting a great improvement for practical applications. Particularly in the case of Pt/C-Bi, the improvement is such that within 0.6 V (from 0.7 to 0.1 V) the power densities are between 7 and 9 mW/cm2. The results obtained with these catalysts are in the same range as those obtained with other bimetallic catalysts comprising of PtRu and PtSn, which are currently considered to be the best for these type of fuel cells and that are obtained by more complicated (and consequently more expensive) methods.

Figueiredo, Marta C.; Sorsa, Olli; Doan, Nguyet; Pohjalainen, Elina; Hildebrand, Helga; Schmuki, Patrik; Wilson, Benjamin P.; Kallio, Tanja

2015-02-01

126

Performance of PEM Liquid-Feed Direct Methanol-Air Fuel Cells  

NASA Technical Reports Server (NTRS)

A direct methanol-air fuel cell operating at near atmospheric pressure, low-flow rate air, and at temperatures close to 60oC would tremendously enlarge the scope of potential applications. While earlier studies have reported performance with oxygen, the present study focuses on characterizing the performance of a PEM liquid feed direct methanol-air cell consisting of components developed in house. These cells employ Pt-Ru catalyst in the anode, Pt at the cathode and Nafion 117 as the PEM. The effect of pressure, flow rate of air and temperature on cell performance has been studied. With air, the performance level is as high as 0.437 V at 300 mA/cm2 (90oC, 20 psig, and excess air flow) has been attained. Even more significant is the performance level at 60oC, 1 atm and low flow rates of air (3-5 times stoichiometric), which is 0.4 V at 150 mA/cm2. Individual electrode potentials for the methanol and air electrode have been separated and analyzed. Fuel crossover rates and the impact of fuel crossover on the performance of the air electrode have also been measured. The study identifies issues specific to the methanol-air fuel cell and provides a basis for improvement strategies.

Narayanan, S. R.

1995-01-01

127

In vitro analysis of nanoparticulate hydroxyapatite/chitosan composites as potential drug delivery platforms for the sustained release of antibiotics in the treatment of osteomyelitis.  

PubMed

Nanoparticulate composites of hydroxyapatite (HAp) and chitosan were synthesized by ultrasound-assisted sequential precipitation and characterized for their microstructure at the atomic scale, surface charge, drug release properties, and combined antibacterial and osteogenic response. Crystallinity of HAp nanoparticles was reduced because of the interference of the surface layers of chitosan with the dissolution/reprecipitation-mediated recrystallization mechanism that conditions the transition from the as-precipitated amorphous calcium phosphate phase to the most thermodynamically stable one--HAp. Embedment of 5-10 nm sized, narrowly dispersed HAp nanoparticles within the polymeric matrix mitigated the burst release of the small molecule model drug, fluorescein, bound to HAp by physisorption, and promoted sustained-release kinetics throughout the 3 weeks of release time. The addition of chitosan to the particulate drug carrier formulation, however, reduced the antibacterial efficacy against S aureus. Excellent cell spreading and proliferation of osteoblastic MC3T3-E1 cells evidenced on microscopic conglomerates of HAp nanoparticles in vitro also markedly diminished on HAp/chitosan composites. Mitochondrial dehydrogenase activity exhibited normal values only for HAp/chitosan particle concentrations of up to 2 mg/cm(2) and significantly dropped, by about 50%, at higher particle concentrations (4 and 8 mg/cm(2)). The gene expression of osteocalcin, a mineralization inductor, and the transcription factor Runx2 was downregulated in cells incubated in the presence of 3 mg/cm(2) HAp/chitosan composite particles, whereas the expression of osteopontin, a potent mineralization inhibitor, was upregulated, further demonstrating the partially unfavorable osteoblastic cell response to the given particles. The peak in the expression of osteogenic markers paralleling the osteoblastic differentiation was also delayed most for the cell population incubated with HAp/chitosan particles. Overall, the positive effect of chitosan coating on the drug elution profile of HAp nanoparticles as carriers for the controlled delivery of antibiotics in the treatment of osteomyelitis was compensated for by the lower bacteriostatic efficiency and the comparatively unviable cell response to the composite material, especially at higher dosages. PMID:24382825

Uskokovi?, Vuk; Desai, Tejal A

2014-02-01

128

In Vitro Analysis of Nanoparticulate Hydroxyapatite/Chitosan Composites as Potential Drug Delivery Platforms for the Sustained Release of Antibiotics in the Treatment of Osteomyelitis  

PubMed Central

Nanoparticulate composites of hydroxyapatite (HAp) and chitosan were synthesized by ultrasound-assisted sequential precipitation and characterized for their microstructure at the atomic scale, surface charge, drug release properties, and combined antibacterial and osteogenic response. Crystallinity of HAp nanoparticles was reduced because of the interference of the surface layers of chitosan with the dissolution/reprecipitation-mediated recrystallization mechanism that conditions the transition from the as-precipitated amorphous calcium phosphate phase to the most thermodynamically stable one—HAp. Embedment of 5–10 nm sized, narrowly dispersed HAp nanoparticles within the polymeric matrix mitigated the burst release of the small molecule model drug, fluorescein, bound to HAp by physisorption, and promoted sustained-release kinetics throughout the 3 weeks of release time. The addition of chitosan to the particulate drug carrier formulation, however, reduced the antibacterial efficacy against S aureus. Excellent cell spreading and proliferation of osteoblastic MC3T3-E1 cells evidenced on microscopic conglomerates of HAp nanoparticles in vitro also markedly diminished on HAp/chitosan composites. Mitochondrial dehydrogenase activity exhibited normal values only for HAp/chitosan particle concentrations of up to 2 mg/cm2 and significantly dropped, by about 50%, at higher particle concentrations (4 and 8 mg/cm2). The gene expression of osteocalcin, a mineralization inductor, and the transcription factor Runx2 was downregulated in cells incubated in the presence of 3 mg/cm2 HAp/chitosan composite particles, whereas the expression of osteopontin, a potent mineralization inhibitor, was upregulated, further demonstrating the partially unfavorable osteoblastic cell response to the given particles. The peak in the expression of osteogenic markers paralleling the osteoblastic differentiation was also delayed most for the cell population incubated with HAp/chitosan particles. Overall, the positive effect of chitosan coating on the drug elution profile of HAp nanoparticles as carriers for the controlled delivery of antibiotics in the treatment of osteomyelitis was compensated for by the lower bacteriostatic efficiency and the comparatively unviable cell response to the composite material, especially at higher dosages. PMID:24382825

USKOKOVI?, VUK; DESAI, TEJAL A.

2014-01-01

129

Nanoparticulate iron(III) oxo-hydroxide delivers safe iron that is well absorbed and utilised in humans  

PubMed Central

Iron deficiency is the most common nutritional disorder worldwide with substantial impact on health and economy. Current treatments predominantly rely on soluble iron which adversely affects the gastrointestinal tract. We have developed organic acid-modified Fe(III) oxo-hydroxide nanomaterials, here termed nano Fe(III), as alternative safe iron delivery agents. Nano Fe(III) absorption in humans correlated with serum iron increase (P < 0.0001) and direct in vitro cellular uptake (P = 0.001), but not with gastric solubility. The most promising preparation (iron hydroxide adipate tartrate: IHAT) showed ~80% relative bioavailability to Fe(II) sulfate in humans and, in a rodent model, IHAT was equivalent to Fe(II) sulfate at repleting haemoglobin. Furthermore, IHAT did not accumulate in the intestinal mucosa and, unlike Fe(II) sulfate, promoted a beneficial microbiota. In cellular models, IHAT was 14-fold less toxic than Fe(II) sulfate/ascorbate. Nano Fe(III) manifests minimal acute intestinal toxicity in cellular and murine models and shows efficacy at treating iron deficiency anaemia. From the Clinical Editor This paper reports the development of novel nano-Fe(III) formulations, with the goal of achieving a magnitude less intestinal toxicity and excellent bioavailability in the treatment of iron deficiency anemia. Out of the tested preparations, iron hydroxide adipate tartrate met the above criteria, and may become an important tool in addressing this common condition. PMID:24983890

Pereira, Dora I.A.; Bruggraber, Sylvaine F.A.; Faria, Nuno; Poots, Lynsey K.; Tagmount, Mani A.; Aslam, Mohamad F.; Frazer, David M.; Vulpe, Chris D.; Anderson, Gregory J.; Powell, Jonathan J.

2014-01-01

130

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

PubMed Central

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

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

2014-01-01

131

Selective electrocatalysts toward a prototype of the membraneless direct methanol fuel cell.  

PubMed

Mastery over the structure of nanomaterials enables control of their properties to enhance their performance for a given application. Herein we demonstrate the design and fabrication of Pt-based nanomaterials with enhanced catalytic activity and superior selectivity toward the reactions in direct methanol fuel cells (DMFCs) upon the deep understanding of the mechanisms of these electrochemical reactions. In particular, the ternary Au@Ag2S-Pt nanocomposites display superior methanol oxidation reaction (MOR) selectivity due to the electronic coupling effect among different domains of the nanocomposites, while the cage-bell structured Pt-Ru nanoparticles exhibit excellent methanol tolerance for oxygen reduction reaction (ORR) at the cathode because of the differential diffusion of methanol and oxygen in the porous Ru shell of the cage-bell nanoparticles. The good catalytic selectivity of these Pt-based nanomaterials via structural construction enables a DMFC to be built without a proton exchange membrane between the fuel electrode and the oxygen electrode. PMID:24448514

Feng, Yan; Yang, Jinhua; Liu, Hui; Ye, Feng; Yang, Jun

2014-01-01

132

Selective electrocatalysts toward a prototype of the membraneless direct methanol fuel cell  

PubMed Central

Mastery over the structure of nanomaterials enables control of their properties to enhance their performance for a given application. Herein we demonstrate the design and fabrication of Pt-based nanomaterials with enhanced catalytic activity and superior selectivity toward the reactions in direct methanol fuel cells (DMFCs) upon the deep understanding of the mechanisms of these electrochemical reactions. In particular, the ternary Au@Ag2S-Pt nanocomposites display superior methanol oxidation reaction (MOR) selectivity due to the electronic coupling effect among different domains of the nanocomposites, while the cage-bell structured Pt-Ru nanoparticles exhibit excellent methanol tolerance for oxygen reduction reaction (ORR) at the cathode because of the differential diffusion of methanol and oxygen in the porous Ru shell of the cage-bell nanoparticles. The good catalytic selectivity of these Pt-based nanomaterials via structural construction enables a DMFC to be built without a proton exchange membrane between the fuel electrode and the oxygen electrode. PMID:24448514

Feng, Yan; Yang, Jinhua; Liu, Hui; Ye, Feng; Yang, Jun

2014-01-01

133

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

134

Study of catalysis for solid oxide fuel cells and direct methanol fuel cells  

NASA Astrophysics Data System (ADS)

Fuel cells offer the enticing promise of cleaner electricity with lower environmental impact than traditional energy conversion technologies. Driven by the interest in power sources for portable electronics, and distributed generation and automotive propulsion markets, active development efforts in the technologies of both solid oxide fuel cell (SOFC) and direct methanol fuel cell (DMFC) devices have achieved significant progress. However, current catalysts for fuel cells are either of low catalytic activity or extremely expensive, presenting a key barrier toward the widespread commercialization of fuel cell devices. In this thesis work, atomic layer deposition (ALD), a novel thin film deposition technique, was employed to apply catalytic Pt to SOFC, and investigate both Pt skin catalysts and Pt-Ru catalysts for methanol oxidation, a very important reaction for DMFC, to increase the activity and utilization levels of the catalysts while simultaneously reducing the catalyst loading. For SOFCs, we explored the use of ALD for the fabrication of electrode components, including an ultra-thin Pt film for use as the electrocatalyst, and a Pt mesh structure for a current collector for SOFCs, aiming for precise control over the catalyst loading and catalyst geometry, and enhancement in the current collect efficiency. We choose Pt since it has high chemical stability and excellent catalytic activity for the O2 reduction reaction and the H2 oxidation reaction even at low operating temperatures. Working SOFC fuel cells were fabricated with ALD-deposited Pt thin films as an electrode/catalyst layer. The measured fuel cell performance reveals that comparable peak power densities were achieved for ALD-deposited Pt anodes with only one-fifth of the Pt loading relative to a DC-sputtered counterpart. In addition to the continuous electrocatalyst layer, a micro-patterned Pt structure was developed via the technique of area selective ALD. By coating yttria-stabilized zirconia, a typical solid oxide electrolyte, with patterned (octadecyltrichlorosilane) ODTS self-assembled monolayers (SAMs), Pt thin films were grown selectively on the SAM-free surface regions. Features with sizes as small as 2 mum were deposited by this combined ALD-muCP method. The micro-patterned Pt structure deposited by area selective ALD was applied to SOFCs as a current collector grid/patterned catalyst. An improvement in the fuel cell performance by a factor of 10 was observed using the Pt current collector grids/patterned catalyst integrated onto cathodic La0.6Sr 0.4Co0.2Fe0.8O3-delta. For possible catalytic anodes in DMFCs employing a 1:1 stoichiometric methanol-water reforming mixture, two strategies were employed in this thesis. One approach is to fabricate skin catalysts, where ALD Pt films of various thicknesses were used to coat sputtered Ru films forming Pt skin catalysts for study of methanol oxidation. Another strategy is to replace or alloy Pt with Ru; for this effort, both dc-sputtering and atomic layer deposition were employed to fabricate Pt-Ru catalysts of various Ru contents. The electrochemical behavior of all of the Pt skin catalysts, the DC co-sputtered Pt-Ru catalysts and the ALD co-deposited Pt-Ru catalysts were evaluated at room temperature for methanol oxidation using cyclic voltammetry and chronoamperometry in highly concentrated 16.6 M MeOH, which corresponds to the stoichiometric fuel that will be employed in next generation DMFCs that are designed to minimize or eliminate methanol crossover. The catalytic activity of sputtered Ru catalysts toward methanol oxidation is strongly enhanced by the ALD Pt overlayer, with such skin layer catalysts displaying superior catalytic activity over pure Pt. For both the DC co-sputtered catalysts and ALD co-deposited catalysts, the electrochemical studies illustrate that the optimal stoichiometry ratio for Pt to Ru is approximately 1:1, which is in good agreement with most literature.

Jiang, Xirong

135

Study of operating conditions and cell design on the performance of alkaline anion exchange membrane based direct methanol fuel cells  

NASA Astrophysics Data System (ADS)

Direct methanol fuel cells using an alkaline anion exchange membrane (AAEM) were prepared, studied, and optimized. The effects of fuel composition and electrode materials were investigated. Membrane electrode assemblies fabricated with Tokuyama® AAEM and commercial noble metal catalysts achieved peak power densities between 25 and 168 mW cm-2 depending on the operating temperature, fuel composition, and electrode materials used. Good electrode wettability at the anode was found to be very important for achieving high power densities. The performance of the best AAEM cells was comparable to Nafion®-based cells under similar conditions. Factors limiting the performance of AAEM MEAs were found to be different from those of Nafion® MEAs. Improved electrode kinetics for methanol oxidation in alkaline electrolyte at Pt-Ru are apparent at low current densities. At high current densities, rapid CO2 production converts the hydroxide anions, necessary for methanol oxidation, to bicarbonate and carbonate: consequently, the membrane and interfacial conductivity are drastically reduced. These phenomena necessitate the use of aqueous potassium hydroxide and wettable electrode materials for efficient hydroxide supply to the anode. However, aqueous hydroxide is not needed at the cathode. Compared to AAEM-based fuel cells, methanol fuel cells based on proton-conducting Nafion® retain better performance at high current densities by providing the benefit of carbon dioxide rejection.

Prakash, G. K. Surya; Krause, Frederick C.; Viva, Federico A.; Narayanan, S. R.; Olah, George A.

2011-10-01

136

Novel O2-enhanced methanol oxidation performance at Pt-Ru-C sputtered anode in direct methanol fuel cell  

NASA Astrophysics Data System (ADS)

We have developed a novel anode catalyst for the direct methanol fuel cell (DMFC). A Pt-Ru-C electrode was prepared by a co-sputtering technique and compared with Pt and Pt-Ru sputtered electrodes for the methanol electro-oxidation reaction. The prepared Pt-Ru-C electrode with a specific atomic ratio showed a remarkable O2-enhanced methanol oxidation performance by O2 addition to methanol as a fuel. For practical utilization, the relationship between the O2-enhanced methanol oxidation activity and the thermal stability of the Pt-Ru-C sputtered electrode was evaluated using a post-annealing treatment. It is found that the O2-enhanced methanol oxidation activity of the Pt-Ru-C electrodes is retained if the annealing temperature is less than or equal to 100 °C. Finally, the DMFC performance was assessed using a single DMFC cell incorporating a membrane electrode assembly with Pt-Ru-C which was hot-pressed at 100 °C. The O2-enhanced methanol oxidation was observed at a single DMFC cell also. Moreover, the enhanced reaction was recognized in DMFC power generation by feeding methanol and oxygen to the anode and oxygen to the cathode.

Shironita, Sayoko; Ueda, Masafumi; Matsumoto, Yosuke; Umeda, Minoru

2013-12-01

137

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.

2012-08-29

138

Directional display  

NASA Astrophysics Data System (ADS)

The directional display contains and shows several images -- which particular image is visible depends on the viewing direction. This is achieved by packing information at high density on a surface, by a certain back illumination technique, and by explicit mathematical formulas which eliminate projection deformations and make it possible to automatize the production of directional displays. The display is illuminated but involves no electronic components. Patent is pending for the directional display. Directional dependency of an image can be used in several ways. One is to achieve three-dimensional effects. In contrast to that of holograms, large size and full color involve no problems. Another application of the technique is to show moving sequences. Yet another is to make a display more directionally independent than conventional displays. It is also possible and useful in several contexts to show different text in different directions with the same display. The features can be combined.

Lennerstad, Hakan

1997-05-01

139

Improved Anode for a Direct Methanol Fuel Cell  

NASA Technical Reports Server (NTRS)

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the catalyst by increasing electrical connectivity between catalyst particles. However, the relatively low density of carbon results in thick catalyst layers that impede the mass transport of methanol to the catalytic sites. Also, the electrical conductivity of carbon is less than 1/300th of typical metals. Furthermore, the polymer-electrolyte membrane material is acidic and most metals are not chemically stable in contact with it. Finally, a material that conducts electrons (but not protons) does not contribute to the needed transport of protons produced in the electro-oxidation reaction.

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

140

Directing 101.  

ERIC Educational Resources Information Center

Providing an introduction to anyone considering directing as a field of study or career, this book takes a broad look at the process of directing and encourages students and professionals alike to look outside of the movie industry for inspiration. Chapters in the book discuss selecting and acquiring material; budgeting and financing; casting and…

Pintoff, Ernest

141

Recent advances in direct methanol fuel cells at Los Alamos National Laboratory  

NASA Astrophysics Data System (ADS)

This paper describes recent advances in the science and technology of direct methanol fuel cells (DMFCs) made at Los Alamos National Laboratory (LANL). The effort on DMFCs at LANL includes work devoted to portable power applications, funded by the Defense Advanced Research Project Agency (DARPA), and work devoted to potential transport applications, funded by the US DOE. We describe recent results with a new type of DMFC stack hardware that allows to lower the pitch per cell to 2 mm while allowing low air flow and air pressure drops. Such stack technology lends itself to both portable power and potential transport applications. Power densities of 300 W/l and 1 kW/l seem achievable under conditions applicable to portable power and transport applications, respectively. DMFC power system analysis based on the performance of this stack, under conditions applying to transport applications (joint effort with U.C. Davis), has shown that, in terms of overall system efficiency and system packaging requirements, a power source for a passenger vehicle based on a DMFC could compete favorably with a hydrogen-fueled fuel cell system, as well as with fuel cell systems based on fuel processing on board. As part of more fundamental studies performed, we describe optimization of anode catalyst layers in terms of PtRu catalyst nature, loading and catalyst layer composition and structure. We specifically show that, optimized content of recast ionic conductor added to the catalyst layer is a sensitive function of the nature of the catalyst. Other elements of membrane/electrode assembly (MEA) optimization efforts are also described, highlighting our ability to resolve, to a large degree, a well-documented problem of polymer electrolyte DMFCs, namely "methanol crossover". This was achieved by appropriate cell design, enabling fuel utilization as high as 90% in highly performing DMFCs.

Ren, Xiaoming; Zelenay, Piotr; Thomas, Sharon; Davey, John; Gottesfeld, Shimshon

142

Improved Cathode Structure for a Direct Methanol Fuel Cell  

NASA Technical Reports Server (NTRS)

An improved cathode structure on a membrane/electrode assembly has been developed for a direct methanol fuel cell, in a continuing effort to realize practical power systems containing such fuel cells. This cathode structure is intended particularly to afford better cell performance at a low airflow rate. A membrane/electrode assembly of the type for which the improved cathode structure was developed (see Figure 1) is fabricated in a process that includes brush painting and spray coating of catalyst layers onto a polymer-electrolyte membrane and onto gas-diffusion backings that also act as current collectors. The aforementioned layers are then dried and hot-pressed together. When completed, the membrane/electrode assembly contains (1) an anode containing a fine metal black of Pt/Ru alloy, (2) a membrane made of Nafion 117 or equivalent (a perfluorosulfonic acid-based hydrophilic, proton-conducting ion-exchange polymer), (3) a cathode structure (in the present case, the improved cathode structure described below), and (4) the electrically conductive gas-diffusion backing layers, which are made of Toray 060(TradeMark)(or equivalent) carbon paper containing between 5 and 6 weight percent of poly(tetrafluoroethylene). The need for an improved cathode structure arises for the following reasons: In the design and operation of a fuel-cell power system, the airflow rate is a critical parameter that determines the overall efficiency, cell voltage, and power density. It is desirable to operate at a low airflow rate in order to obtain thermal and water balance and to minimize the size and mass of the system. The performances of membrane/electrode assemblies of prior design are limited at low airflow rates. Methanol crossover increases the required airflow rate. Hence, one way to reduce the required airflow rate is to reduce the effect of methanol crossover. Improvement of the cathode structure - in particular, addition of hydrophobic particles to the cathode - has been demonstrated to mitigate the effects of crossover and decrease the airflow required.

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

143

Tech Directions  

NSDL National Science Digital Library

Tech Directions is a company which offers a wide array of titles in the fields of technology, career and technical education and related industrial fields. The company offers books, project kits, posters and more for use in the classroom.

2011-05-11

144

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.

2014-09-24

145

Directing thrombin.  

PubMed

Following initiation of coagulation as part of the hemostatic response to injury, thrombin is generated from its inactive precursor prothrombin by factor Xa as part of the prothrombinase complex. Thrombin then has multiple roles. The way in which thrombin interacts with its many substrates has been carefully scrutinized in the past decades, but until recently there has been little consideration of how its many functions are coordinated or directed. Any understanding of how it is directed requires knowledge of its structure, how it interacts with its substrates, and the role of any cofactors for its interaction with substrates. Recently, many of the interactions of thrombin have been clarified by crystal structure and site-directed mutagenesis analyses. These analyses have revealed common residues used for recognition of some substrates and overlapping surface exosites used for recognition by cofactors. As many of its downstream reactions are cofactor driven, competition between cofactors for exosites must be a dominant mechanism that determines the fate of thrombin. This review draws together much recent work that has helped clarify structure function relationships of thrombin. It then attempts to provide a cogent proposal to explain how thrombin activity is directed during the hemostatic response. PMID:15994286

Lane, David A; Philippou, Helen; Huntington, James A

2005-10-15

146

Dicey Directions  

NSDL National Science Digital Library

In this game, learners are stuck in a right turn only world! Learners take turns rolling a die and moving their game pieces along the lines of a grid to get "home," by only making right turns. This activity provides learners with an opportunity to think about the relative nature of directional terms such as right and left. This activity guide contains sample questions to ask, literary connections, extensions, and alignment to local and national standards.

Children's Museum of Houston

2014-09-19

147

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

SciTech Connect

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

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

2014-02-17

148

Nanoparticulate systems for brain delivery of drugs  

Microsoft Academic Search

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

Jörg Kreuter

2001-01-01

149

Cyclosporin nanoparticulate lipospheres for oral administration.  

PubMed

Cyclosporin is a first line immunosuppressive drug used to prevent transplant rejection and to treat autoimmune diseases. It is a hydrophobic cyclic peptide built from nonmammalian amino acids with low oral bioavailability. The aim of this study was to develop an oral delivery system for cyclosporin A (CyA) and investigate the effect of composition and particle size of the CyA lipid nanoparticles (lipospheres) on the oral bioavailability of this drug. Dispersible concentrated oil formulations that upon mixing in water spontaneously form a nanodispersion were developed. The concentrated oil formulations were clear solutions composed of the drug, a solid triglyceride, a water miscible organic solvent, and a mixture of surfactants and emulsifiers. The activity of the formulated cyclosporin was determined in vitro following the effect on the proliferation of T cells. The oral bioavailability was determined on humans following the cyclosporin blood levels after oral intake of formulated cyclosporin. Cyclosporin dispersion systems resulting in particle size of 25 to 400 nm were prepared from acceptable pharmceutical components. The composition of the surfactants and emulsifiers, the lipid core component, and the amount and type of the water miscible organic solvent N-methylpyrrolidone (NMP) and alcohols had a strong effect on the particle size of the dispersions. All formulations were reproducible and stable at room temperature for at least 6 months, with full activity of cyclosporin retained. Human oral bioavaiability study indicated a correlation between the AUC and C(max) and the particle size of the dispersion. A C(max) of approximately 1300 ng/mL was found after 2 h of oral intake of four capsules, each loaded with 50 mg cyclosporin. PMID:15067702

Bekerman, Tania; Golenser, Jacob; Domb, Abraham

2004-05-01

150

I. Authority President's Directive 18 ("Directive 18").  

E-print Network

of the College of the Arts only when listed in a script as a required part of a performance. SmokingI. Authority President's Directive 18 ("Directive 18"). II. Scope Directive 18 prohibits smoking. · Vehicles owned, leased or rented by the university or one of the university's auxiliaries. Smoking

de Lijser, Peter

151

Predicting link directions using local directed path  

NASA Astrophysics Data System (ADS)

Link prediction in directed network is attracting growing interest among many network scientists. Compared with predicting the existence of a link, determining its direction is more complicated. In this paper, we propose an efficient solution named Local Directed Path to predict link direction. By adding an extra ground node to the network, we solve the information loss problem in sparse network, which makes our method effective and robust. As a quasi-local method, our method can deal with large-scale networks in a reasonable time. Empirical analysis on real networks shows that our method can correctly predict link directions, which outperforms some local and global methods.

Wang, Xiaojie; Zhang, Xue; Zhao, Chengli; Xie, Zheng; Zhang, Shengjun; Yi, Dongyun

2015-02-01

152

Multimode directional telesonar transducer  

Microsoft Academic Search

Directional transducers will improve the performance of undersea acoustic modems. Current designs provide only vertical directionality with omni-directionality in the horizontal plane. Horizontal directionality can yield a higher source level and higher received signal to noise through the increase in the DI or equivalently the narrower beam pattern of the device. Moreover, a horizontal steered directive beam allows selective and

A. L. Butler; J. L. Butler; W. L. Dalton; J. A. Rice

2000-01-01

153

Directed network modules  

Microsoft Academic Search

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 Rényi graph both analytically and numerically. We also analyse four real-world directed networks, including Google's

Gergely Palla; Illés J. Farkas; Péter Pollner; Imre Derényi; Tamás Vicsek

2007-01-01

154

Direct Manipulation Interfaces.  

ERIC Educational Resources Information Center

This paper presents a cognitive account of both the advantages and disadvantages of direct manipulation interfaces, i.e., the use of icons to manipulate and interact directly with data rather than writing programs or calling on a set of statistical subroutines. Two underlying phenomena that give rise to the sensation of directness are identified.…

Hutchins, Edwin L.; And Others

155

Direct Instruction News, 2001.  

ERIC Educational Resources Information Center

These three issues of a newsletter offer diverse kinds of information deemed to be of interest to Association for Direct Instruction (ADI) members--stories of successful implementations in different settings, write-ups of ADI awards, tips on "how to" deliver direct instruction (DI) more effectively, topical articles focused on particular types of…

Tarver, Sara, Ed.

2001-01-01

156

School Direct application  

E-print Network

of places by School Direct strand, subject, partner teacher training provider/s and available places will probably want to combine any further training with actually doing the job. Now with School Direct, you, will have a job in mind, just for you, and there is financial support available throughout your training. It

157

Direct current transformer  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

158

Modelling directional solidification  

NASA Technical Reports Server (NTRS)

The long range goal of this program is to develop an improved understanding of phenomena of importance to directional solidification and to enable explanation and prediction of differences in behavior between solidification on Earth and in space. Current emphasis is on determining the influence of perturbations on directional solidification.

Wilcox, William R.

1991-01-01

159

Direct Support Workforce Development.  

ERIC Educational Resources Information Center

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

Impact, 1998

1998-01-01

160

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

161

Directable photorealistic liquids  

Microsoft Academic Search

We present a method for the directable animation of photorealistic liquids using the particle level set method to obtain smooth, visually pleasing complex liquid surfaces. We also provide for a degree of control common to particle-only based simulation techniques. A variety of directable liquid primitive variables, including the isosurface value, velocity, and viscosity, can be set throughout the liquid. Interaction

N. Rasmussen; D. Enright; D. Nguyen; S. Marino; N. Sumner; W. Geiger; S. Hoon; R. Fedkiw

2004-01-01

162

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.

163

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

164

The European Vibration Directive  

Microsoft Academic Search

The European Union adopted a Directive in 2002 on minimum requirements for the health and safety of workers exposed to vibration. This is known as the Physical Agents (Vibration) Directive. It builds on existing general employers' duties to manage risks to health and safety, and introduces exposure action and limit values for both hand-arm vibration and whole-body vibration, setting minimum

Chris M. NELSON; Paul F. BRERETON

2005-01-01

165

Advance Directives (Psychiatric)  

MedlinePLUS

... to advocate for the use of "psychiatric living wills" as a mechanism for refusing psychiatric treatment. All of the state laws authorizing psychiatric advance directives except Maine specify that ...

166

Directed line liquids  

SciTech Connect

This thesis is devoted to the study of ensembles of dense directed lines. These lines are principally to be thought of as polymers, though they also have the morphology of flux lines in high temperature superconductors, strings of colloidal spheres in electrorheological fluids and the world lines of quantum mechanical bosons. The authors discuss how directed polymer melts, string-like formations in electrorheological and ferro-fluids, flux lines in high temperature superconductors and the world lines of quantum mechanical bosons all share similar descriptions. They study a continuous transition in all of these systems, and then study the critical mixing properties of binary mixtures of directed polymers through the renormalization group. They predict the exponents for a directed polymer blend consolute point and a novel two-phase superfluid liquid-gas critical point.

Kamien, R.D.

1992-01-01

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 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

169

BIOCHEMISTRY: Directing Biosynthesis  

NSDL National Science Digital Library

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

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

2006-10-27

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

Estimating directional epistasis  

PubMed Central

Epistasis, i.e., the fact that gene effects depend on the genetic background, is a direct consequence of the complexity of genetic architectures. Despite this, most of the models used in evolutionary and quantitative genetics pay scant attention to genetic interactions. For instance, the traditional decomposition of genetic effects models epistasis as noise around the evolutionarily-relevant additive effects. Such an approach is only valid if it is assumed that there is no general pattern among interactions—a highly speculative scenario. Systematic interactions generate directional epistasis, which has major evolutionary consequences. In spite of its importance, directional epistasis is rarely measured or reported by quantitative geneticists, not only because its relevance is generally ignored, but also due to the lack of simple, operational, and accessible methods for its estimation. This paper describes conceptual and statistical tools that can be used to estimate directional epistasis from various kinds of data, including QTL mapping results, phenotype measurements in mutants, and artificial selection responses. As an illustration, I measured directional epistasis from a real-life example. I then discuss the interpretation of the estimates, showing how they can be used to draw meaningful biological inferences. PMID:25071828

Le Rouzic, Arnaud

2014-01-01

172

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

173

Direct conversion technology  

NASA Technical Reports Server (NTRS)

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.

1989-01-01

174

Directed flux motor  

NASA Technical Reports Server (NTRS)

A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.

Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

2011-01-01

175

Microsegregation during directional solidification  

NASA Technical Reports Server (NTRS)

During the directional solidification of alloys, solute inhomogeneities transverse to the growth direction arise due to morphological instabilities (leading to cellular or dendritic growth) and/or due to convection in the melt. In the absence of convection, the conditions for the onset of morphological instability are given by the linear stability analysis of Mullins and Sekerka. For ordinary solidification rates, the predictions of linear stability analysis are similar to the constitutional supercooling criterion. However, at very rapid solidification rates, linear stability analysis predicts a vast increase in stabilization in comparison to constitutional supercooling.

Coriell, S. R.; Mcfadden, G. B.

1984-01-01

176

Direct energy conversion device  

Microsoft Academic Search

A method and apparatus are described for directly converting heat to electricity within an array of thermoelements and heat pipes. The thermoelectric generator contains two conduits for two fluid streams, and a plurality of thermal bridges connecting points in both fluid streams, placing them in an overall counterflow heat exchange relationship. Each thermal bridge comprises at least one heat exchange

Stachurski; J. Z. O

1978-01-01

177

Directional gamma detector  

DOEpatents

An improved directional gamma radiation detector has a collector sandwiched etween two layers of insulation of varying thicknesses. The collector and insulation layers are contained within an evacuated casing, or emitter, which releases electrons upon exposure to gamma radiation. Delayed electrons and electrons entering the collector at oblique angles are attenuated as they pass through the insulation layers on route to the collector.

LeVert, Francis E. (Downers Grove, Knoxville, TN); Cox, Samson A. (Downers Grove, IL)

1981-01-01

178

Direct fired heat exchanger  

DOEpatents

A gas-to-liquid heat exchanger system which transfers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine, to a liquid, generally an absorbent solution. The heat exchanger system is in a counterflow fluid arrangement which creates a more efficient heat transfer.

Reimann, Robert C. (Lafayette, NY); Root, Richard A. (Spokane, WA)

1986-01-01

179

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

180

Direct from CDC's Environmental  

E-print Network

Direct from CDC's Environmental Health Services Branch CAPT Daniel M. Harper, M.P.H. A Diverse Environmental Public Health Workforce to Meet the Diverse Environmental Health Challenges on environmental health and to build part nerships in the profession. In pursuit of these goals, we will feature

181

Direct from CDC's Environmental  

E-print Network

Direct from CDC's Environmental Health Services Branch Brian Hubbard, M.P.H. Editor the Environmental Health Services Branch (EHSB) of the Centers for Disease Con trol and Prevention (CDC) in every environmental health programs and professionals to antici pate, identify, and respond to adverse envi ronmental

182

Direct from CDC's Environmental  

E-print Network

Direct from CDC's Environmental Health Services Branch CAPT John Sarisky, R.S., M.P.H. Developing Environmental Public Health Leadership Editor's note: NEHA strives to provide up to of these goals, we will feature a column from the Environmental Health Services Branch (EHSB) of the Centers

183

Direct from CDC's Environmental  

E-print Network

Direct from CDC's Environmental Health Services Branch Daneen Farrow Collier, M.S.P.H. Editor's note: NEHA strives to pro vide up-to-date and relevant informa tion on environmental health the Environmental Health Services Branch (EHSB) of the Centers for Disease Control and Pre vention (CDC) in every

184

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.

185

Fetch directed instruction prefetching  

Microsoft Academic Search

Instruction supply is a crucial component of processor performance. Instruction prefetching has been proposed as a mechanism to help reduce instruction cache misses, which in turn can help increase instruction supply to the processor. In this paper we examine a new instruction prefetch architecture called Fetch Directed Prefetching, and compare it to the performance of next-line prefetching and streaming buffers.

Glenn Reinmant; Brad Calder; Todd M. Austin

1999-01-01

186

Direct Methanol Fuel Cell  

NSDL National Science Digital Library

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

187

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

188

Audio direct broadcast satellites  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

189

Using directionality in mobile routing  

Microsoft Academic Search

The increased usage of directional methods of communications has prompted research into leveraging directionality in every layer of the network stack. In this paper, we explore the use of directionality in layer 3 to facilitate routing in highly mobile environments. We introduce mobile orthogonal rendezvous routing protocol (MORRP), a lightweight, but scalable routing protocol utilizing directional communications (such as directional

Bow-Nan Cheng; Murat Yuksel; Shivkumar Kalyanaraman

2008-01-01

190

Directional control of radiant heat  

NASA Technical Reports Server (NTRS)

Surface with grooves having flat bases gives directional emissivities and absorptivities that can be made to approximate a perfect directional surface. Radiant energy can then be transferred in desired directions.

Howell, J. R.; Perlmutter, M.

1970-01-01

191

RICE UNIVERSITY BEAMSWITCH: DIRECTIONAL TRANSMISSION  

E-print Network

RICE UNIVERSITY BEAMSWITCH: DIRECTIONAL TRANSMISSION FOR ENERGY-EFFICIENT WIRELESS COMMUNICATION Directional Transmission for Energy-Efficient Wireless Communication on Mobile Sys- tems Hasan Huseyin Dumanli Directional communication has the potential to improve both the energy efficiency of wireless communication

Zhong, Lin

192

Modelling directional solidification  

NASA Technical Reports Server (NTRS)

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

Wilcox, William R.

1987-01-01

193

[Direct biosynthesis of ethylene].  

PubMed

Ethylene is the most widely used petrochemical feedstock globally. The development of bio-ethylene is essential due to limited fossil fuels and rising oil prices. Bio-ethylene is produced primarily by the dehydration of ethanol, but can alternatively be directly produced from ethylene biosynthesis pathways in plants, algae, or microorganisms by using cheap and renewable substrates. This review addressed the biosynthesis of ethylene in plants and microorganisms, the characterization of key enzymes, genetic engineering strategies for ethylene biosynthesis in microorganisms, and evaluated its perspective and successful cases toward the industrial application. The direct production of bio-ethylene from a biological process in situ is promising to supplement and even replace the petrochemical ethylene production. PMID:24432658

Sun, Zhilan; Chen, Yifeng

2013-10-01

194

Direct heating surface combustor  

NASA Technical Reports Server (NTRS)

The combustor utilizes a non-adiabatic flame to provide low-emission combustion for gas turbines. A fuel-air mixture is directed through a porous wall, the other side of which serves as a combustion surface. A radiant heat sink disposed adjacent to and spaced from the combustion surface controls the combustor flame temperature in order to prevent the formation of oxides of nitrogen. A secondary air flow cools the heat sink. Additionally, up to 100% of secondary air flow is mixed with the combustion products at the direct heating surface combustor to dilute such products thereby reducing exit temperature. However, if less than 100% secondary air is mixed to the combustor, the remainder may be added to the combustion products further downstream.

Beremand, D. G.; Shire, L. I.; Mroz, T. S. (inventors)

1978-01-01

195

Sputum direct fluorescent antibody (DFA)  

MedlinePLUS

Direct immunofluorescence test; Direct fluorescent antibody - sputum ... fluorescent dye are added to the sample. These antibodies are ... bright glow (fluorescence) can be seen in the sputum sample using ...

196

Direct CP violation in  

NASA Astrophysics Data System (ADS)

We study the direct CP violation in the decay process in the standard model. An interesting mechanism involving the charge symmetry violating mixing between and is applied to enlarge the CP asymmetry. We find that the CP-violating asymmetry can be enhanced greatly via this - mixing mechanism when the invariant mass of the pair is in the vicinity of the resonance. With this mechanism, the maximum differential and localized integrated CP asymmetries can reach and , respectively, which is still negligible.

Wang, Chao; Guo, Xin-Heng; Liu, Ying; Li, Rui-Cheng

2014-11-01

197

Directional Hearing Aid  

NASA Technical Reports Server (NTRS)

Hearing-aid device indicates visually whether sound is coming from left, right, back, or front. Device intended to assist individuals who are deaf in at least one ear and unable to discern naturally directions to sources of sound. Device promotes safety in street traffic, on loading docks, and in presence of sirens, alarms, and other warning sounds. Quadraphonic version of device built into pair of eyeglasses and binaural version built into visor.

Jhabvala, M.; Lin, H. C.

1989-01-01

198

Modelling direction solidification  

NASA Technical Reports Server (NTRS)

The overall objective of this program is to develop an improved understanding of some phenomena of importance to directional solidification. The aim of this research is also to help predict differences in behavior between solidification on Earth and solidification in space. In this report, the validity of the Burton-Primslichter equation is explored. The influence of operating variables on grain and twin generation and propagation in single crystals of In sub (x) Ga sub (1-x) Sb is also investigated.

Wilcox, W. R.

1986-01-01

199

New direct thrombin inhibitors  

Microsoft Academic Search

Direct thrombin inhibitors (DTIs) are a class of anticoagulants that bind selectively to thrombin and block its interaction\\u000a with its substrates. Dabigatran etexilate and AZD0837, the new generation of DTIs, are now under intense development, and\\u000a are potentially of great interest for internists. Dabigatran etexilate is a potent, non-peptidic small molecule that specifically\\u000a and reversibly inhibits both free and clot-bound

Alessandro Squizzato; Francesco Dentali; Luigi Steidl; Walter Ageno

2009-01-01

200

Direct conversion technology  

NASA Technical Reports Server (NTRS)

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.

1988-01-01

201

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

202

Roaming Robot: Give Directions  

NSDL National Science Digital Library

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

TERC

2010-01-01

203

Direct to Digital Holography  

SciTech Connect

In this CRADA, Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, testing of DDH for detection of defects in High Aspect Ratio (HAR) structures, development of image processing techniques to enhance detection capabilities through the use of both phase and intensity, and development of methods for autofocus on the DDH tools.

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

2002-06-15

204

Direct to Digital Holography  

SciTech Connect

In this Cooperative Research and Development Agreement (CRADA), Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, testing of DDH for detection of defects in High Aspect Ratio (HAR) structures, development of image processing techniques to enhance detection capabilities through the use of both phase and intensity, and development of methods for autofocus on the DDH tools.

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

2007-09-30

205

Omni-directional railguns  

DOEpatents

A device is disclosed 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. 4 figs.

Shahinpoor, M.

1995-07-25

206

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

207

Direct effects protection  

NASA Technical Reports Server (NTRS)

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

1977-01-01

208

Remote direct memory access  

DOEpatents

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

209

Direct Aerosol Forcing Uncertainty  

DOE Data Explorer

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

Mccomiskey, Allison

210

Direct Aerosol Forcing Uncertainty  

SciTech Connect

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

Mccomiskey, Allison

2008-01-15

211

75 FR 76630 - Direct Investment Surveys: BE-577, Quarterly Survey of U.S. Direct Investment Abroad-Direct...  

Federal Register 2010, 2011, 2012, 2013

...Direct Investment Abroad--Direct Transactions...Reporter With Foreign Affiliate...Direct Investment Abroad--Direct Transactions...Reporter With Foreign Affiliate...Direct Investment Abroad--Direct Transactions...Reporter With Foreign...

2010-12-09

212

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 (107–108 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. PMID:20659684

Paegel, Brian M.; Joyce, Gerald F.

2010-01-01

213

Comprehension of Navigation Directions  

NASA Technical Reports Server (NTRS)

Subjects were shown navigation instructions varying in length directing them to move in a space represented by grids on a computer screen. They followed the instructions by clicking on the grids in the locations specified. Some subjects repeated back the instructions before following them, some did not, and others repeated back the instructions in reduced form, including only the critical words. The commands in each message were presented simultaneously for half of the subjects and sequentially for the others. For the longest messages, performance was better on the initial commands and worse on the final commands with simultaneous than with sequential presentation. Instruction repetition depressed performance, but reduced repetition removed this disadvantage. Effects of presentation format were attributed to visual scanning strategies. The advantage for reduced repetition was attributable either to enhanced visual scanning or to reduced output interference. A follow-up study with auditory presentation supported the visual scanning explanation.

Healy, Alice F.; Schneider, Vivian I.

2002-01-01

214

The direction of gravity  

NASA Astrophysics Data System (ADS)

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

Linder, E. V.

2014-03-01

215

Laser assisted direct manufacturing  

NASA Astrophysics Data System (ADS)

Direct Laser Manufacturing (DLM) with coaxial powder injection (TRUMPF DMD 505 installation) was applied for fabrication of 3D objects from metallic and ceramic powder. One of the advantages of DLM is the possibility to build functionally graded objects in one-step manufacturing cycle by application of a 2-channel powder feeder. Several models with different types of material gradients (smooth, sharp, periodic) and multi-layered structures were manufactured from SS, stellite (Cobalt alloy), Cu and W alloys. Technology of Selective Laser Melting (SLM) was applied for manufacturing of net shaped objects from different powders (PHENIX PM-100 machine) : Inox 904L, Ni625, Cu/Sn, W and Zr02-Y2O3. Performance and limitations of SLM technology for fabrication of elements for chemical and mechanical industries are analysed. Two-component objects (Stainless steel /Cu - H13/CuNi) were fabricated in a two-step manufacturing cycle.

Bertrand, Ph.; Smurov, I.

2007-06-01

216

Site directed recombination  

DOEpatents

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

217

Modelling directional solidification  

NASA Technical Reports Server (NTRS)

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.

1990-01-01

218

Directional multiresolution image representations  

E-print Network

Efficient representation of visual information lies at the foundation of many image processing tasks, including compression, filtering, and feature extraction. Efficiency of a representation refers to the ability to capture significant information of an object of interest in a small description. For practical applications, this representation has to be realized by structured transforms and fast algorithms. Recently, it has become evident that commonly used separable transforms (such as wavelets) are not necessarily best suited for images. Thus, there is a strong motivation to search for more powerful schemes that can capture the intrinsic geometrical structure of pictorial information. This thesis focuses on the development of new “true ” two-dimensional representations for images. The emphasis is on the discrete framework that can lead to algorithmic implementations. The first method constructs multiresolution, local and directional image expansions by using non-separable filter banks. This discrete transform is developed in connection with the continuous-space

Minh N. Do

2001-01-01

219

Direct composite restorative materials.  

PubMed

Composite dental restorative materials have advanced considerably over the past 10 years. Although composites have not totally replaced amalgam, they have become a viable substitute in many situations. Problems still exist with polymerization contraction stress, large differences in the coefficient of thermal expansion (CTE) of composites compared with tooth structure, and with some technique sensitivity; however, new expanding resins, nanofiller technology, and improved bonding systems have the potential to reduce these problems. With increased patient demands for esthetic restorations, the use of direct filling composite materials will continue to grow. The one major caveat to this prediction is that clinicians must continue to use sound judgment on when, where, and how to use composite restoratives in their practices. PMID:17586149

Puckett, Aaron D; Fitchie, James G; Kirk, Pia Chaterjee; Gamblin, Jefferson

2007-07-01

220

Fiber optic TV direct  

NASA Technical Reports Server (NTRS)

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.

1991-01-01

221

Conclusions and Policy Directions,  

SciTech Connect

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

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

2011-01-01

222

Measuring Dark Matter Distribution in Directional Direct Detection  

NASA Astrophysics Data System (ADS)

Direct detection of dark matter with directional sensitivity offers not only measurement of both recoil energy and direction of dark matter, but also a way to understand dark matter distribution in the Galaxy. Maxwell distribution is usually supposed as the distribution near the Earth, however, result of N-body simulations suggest deviation from that due to tidal stream in the Galaxy. We explore the possibility of distinguishing the distribution by direct detection using nuclear emulsions.

Nagao, Keiko I.

2013-12-01

223

Cognitively-inspired direction giving  

E-print Network

Online mapping services and portable GPS units make it easy to get very detailed driving directions. While these directions are sufficient for an automaton to follow, they do not present a big picture description of the ...

Look, Gary Wai Keung, 1978-

2008-01-01

224

Quantum optics: Spin gives direction  

NASA Astrophysics Data System (ADS)

Light emitted near an optical waveguide is captured and equally split into two modes with opposite directions of propagation. By controlling the dipole spin of the emitter, it is possible to break this symmetry and select only one direction.

Marrucci, Lorenzo

2015-01-01

225

Californidfsdfsdfsdfa OMNI-DIRECTIONAL LED  

E-print Network

Californidfsdfsdfsdfa OMNI-DIRECTIONAL LED REPLACEMENT LAMP PERFORMANCE TESTING FINAL REPORT #12 .....................................................................................................................................................9 A-LAMP LED MARKET EVALUATION

California at Davis, University of

226

Ergonomics--future directions.  

PubMed

The International Ergonomics Association plays a leadership role in shaping the future of ergonomics. Having formed nearly 50 years ago for researchers to meet and exchange their findings, it still provides a wide range of opportunities for promoting research and teaching. In 2006, the IEA is also an outward looking organisation with linkages to governments, international agencies and other professional associations. We have many opportunities to extend our engagement with industry and the community through the IEA communication strategy and Technical Committees. Whilst the IEA now has 20 Technical Committees that demonstrate the diversity of ergonomics research there is a growing trend towards integration of specialist areas. The emergence of a holistic approach to research and application of ergonomics is making a new direction for the ergonomics profession. Apart from the role of a technical specialist, the Ergonomist is also a team member with a range of other stakeholders. To be effective in practice, the Ergonomist needs to be a good communicator and "agent of change" who can mentor others to develop simple cost effective interventions. Research is fundamental to the science of ergonomics. Evaluation of interventions remains a major component of future ergonomics research. Sustainable positive outcomes based on a holistic approach will result in a broad uptake of ergonomics findings. In industry future challenges relating to psychological health in developed countries and the informal sector in developing countries are emerging as new areas for research and application of ergonomics. PMID:18572792

Caple, David C

2007-12-01

227

Coatings for directional eutectics  

NASA Technical Reports Server (NTRS)

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 test (1,100 C to 90 C). These coatings were fabricated by first depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam heated source, followed by depositing an aluminizing overlayer. The alloy after exposure with these coatings was denuded of carbide fibers at the substrate/coating interface. It was demonstrated that TaC fiber denudation can be greatly retarded by applying a carbon-bearing coating. The coating was applied by thermal spraying followed by aluminization. Specimens coated with NiCrAlCY+Al survived over 2,000 hours in the cyclic oxidation test with essentially no TaC denudation. Coating ductility was studied for coated and heat-treated bars, and stress rupture life at 871 C and 1,100 C was determined for coated and cycled bars.

Rairden, J. R.; Jackson, M. R.

1976-01-01

228

Multiple direction vibration fixture  

DOEpatents

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

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

1991-01-01

229

Directional solidification under stress  

NASA Astrophysics Data System (ADS)

Directional solidification under uniaxial stress is analyzed. In the absence of stress, it is well known that the moving planar front undergoes a morphological Mullins-Sekerka (MS) instability. Under uniaxial stress, even an interface at rest develops an instability known by the names of Asaro, Tiller, and Grinfeld (ATG). This paper analyzes the coupling between these two instabilities, a situation on which we have recently given a brief account [Durand et al., Phys. Rev. Lett. 76, 3013 (1996)]. We discover that under favorable circumstances a weak uniaxial stress of the order of 1 bar leads to a dramatic change of the Mullins-Sekerka instability. The threshold, together with the microstructure scale, are shifted by amounts going up to one (or several) decade(s). This effect should open new lines of both experimental and theoretical inquiries. A weakly nonlinear analysis is presented by means of a Landau expansion. It is known that the MS bifurcation is subcritical for a small enough solute partition coefficient, and is supercritical otherwise. The ATG instability is always subcritical. The nonlinear evolution of the ATG instability leads to cusps which grow unstably, leading ultimately to the fracture threshold. It is shown here that due to a subtle coupling between both instabilities, the MS bifurcation in its supercritical regime may cause the MS-ATG coupled bifurcation to be supercritical. Discussions and outlooks are presented. In particular it is appealing to speculate that the creation of giant causeways in igneous rocks can be interpreted within the present context.

Cantat, Isabelle; Kassner, Klaus; Misbah, Chaouqi; Müller-Krumbhaar, Heiner

1998-11-01

230

Magnetostrictive direct drive motor  

NASA Technical Reports Server (NTRS)

Highly magnetostrictive materials such as Tb.3Dy.7Fe2, commercially known as TERFENOL-D, have been used to date in a variety of devices such as high power actuators and linear motors. The larger magnetostriction available in twinned single crystal TERFENOL-D, approx. 2000 ppm at moderate magnetic field strengths, makes possible a new generation of magnetomechanical devices. NASA researchers are studying the potential of this material as the basis for a direct microstepping rotary motor with torque densities on the order of industrial hydraulics and five times greater than that of the most efficient, high power electric motors. Such a motor would be a micro-radian stepper, capable of precision movements and self-braking in the power-off state. Innovative mechanical engineering techniques are juxtaposed on proper magnetic circuit design to reduce losses in structural flexures, inertias, thermal expansions, eddy currents, and magneto-mechanical coupling, thus optimizing motor performance and efficiency. Mathematical models are presented, including magnetic, structural, and both linear and nonlinear dynamic calculations and simulations. In addition, test results on prototypes are presented.

Naik, Dipak; Dehoff, P. H.

1991-01-01

231

New Directions in Biotechnology  

NASA Technical Reports Server (NTRS)

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

2003-01-01

232

Coatings for directional eutectics  

NASA Technical Reports Server (NTRS)

Coatings developed to provide oxidation protection for the directionally-solidified eutectic alloy NiTaC-B (4.4 weight percent Cr) were evaluated. Of seven Co-, Fe- and Ni-base coatings that were initially investigated, best resistance to cyclic oxidation was demonstrated by duplex coatings fabricated by depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam source followed by deposition of an Al overlayer using the pack cementation process. It was found that addition of carbon to the coating alloy substantially eliminated the problem of fiber denudation in TaC-type eutectic alloys. Burner rig cycled NiTaC-B samples coated with Ni-20Cr-5Al-0.1C-0.1Y+Al and rupture-tested at 1100 deg C performed as well as or better than uncoated, vacuum cycled and air-tested NiTaC-13; however, a slight degradation with respect to uncoated material was noted in air-stress rupture tests at 870 deg C for both cycled and uncycled samples.

Rairden, J. R.; Jackson, M. R.

1976-01-01

233

Directed Incremental Symbolic Execution  

NASA Technical Reports Server (NTRS)

The last few years have seen a resurgence of interest in the use of symbolic execution -- a program analysis technique developed more than three decades ago to analyze program execution paths. Scaling symbolic execution and other path-sensitive analysis techniques to large systems remains challenging despite recent algorithmic and technological advances. An alternative to solving the problem of scalability is to reduce the scope of the analysis. One approach that is widely studied in the context of regression analysis is to analyze the differences between two related program versions. While such an approach is intuitive in theory, finding efficient and precise ways to identify program differences, and characterize their effects on how the program executes has proved challenging in practice. In this paper, we present Directed Incremental Symbolic Execution (DiSE), a novel technique for detecting and characterizing the effects of program changes. The novelty of DiSE is to combine the efficiencies of static analysis techniques to compute program difference information with the precision of symbolic execution to explore program execution paths and generate path conditions affected by the differences. DiSE is a complementary technique to other reduction or bounding techniques developed to improve symbolic execution. Furthermore, DiSE does not require analysis results to be carried forward as the software evolves -- only the source code for two related program versions is required. A case-study of our implementation of DiSE illustrates its effectiveness at detecting and characterizing the effects of program changes.

Person, Suzette; Yang, Guowei; Rungta, Neha; Khurshid, Sarfraz

2011-01-01

234

Magnetic Properties of Mesoporous and Nano-particulate Metal Oxides   

E-print Network

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

Hill, Adrian H

2009-01-01

235

Nanoparticulate gellants for metallized gelled liquid hydrogen with aluminum  

NASA Technical Reports Server (NTRS)

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

Palaszewski, Bryan; Starkovich, John; Adams, Scott

1996-01-01

236

SEM evaluation of nanoparticulate silver penetration into dentine collagen matrix  

NASA Astrophysics Data System (ADS)

In the present study a novel approach to caries management based on the application of nanoparticles of different nature to increase the mineral phase of demineralized dentin has been developed. Silver nanoparticles have been tested as a material for dentine matrix infiltration. Research findings clearly show that collagen fibers of demineralized dentine could be considered as a scaffold for mineral component delivery and the place where mineral growth can occur.

Bessudnova, Nadezda O.; Bilenko, David I.; Venig, Sergey B.

2014-01-01

237

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

238

Prodrug-based nanoparticulate drug delivery strategies for cancer therapy.  

PubMed

Despite the rapid developments in nanotechnology and biomaterials, the efficient delivery of chemotherapeutic agents is still challenging. Prodrug-based nanoassemblies have many advantages as a potent platform for anticancer drug delivery, such as improved drug availability, high drug loading efficiency, resistance to recrystallization upon encapsulation, and spatially and temporally controllable drug release. In this review, we discuss prodrug-based nanocarriers for cancer therapy, including nanosystems based on polymer-drug conjugates, self-assembling small molecular weight prodrugs and prodrug-encapsulated nanoparticles (NPs). In addition, we discuss new trends in the field of prodrug-based nanoassemblies that enhance the delivery efficiency of anticancer drugs, with special emphasis on smart stimuli-triggered drug release, hybrid nanoassemblies, and combination drug therapy. PMID:25441774

Luo, Cong; Sun, Jin; Sun, Bingjun; He, Zhonggui

2014-11-01

239

Nanoparticulate Cellular Patches for Cell-Mediated Tumoritropic Delivery  

E-print Network

The targeted delivery of therapeutics to tumors remains an important challenge in cancer nanomedicine. Attaching nanoparticles to cells that have tumoritropic migratory properties is a promising modality to address this ...

Cheng, Hao

240

NOVEL NANOPARTICULATE CATALYSTS FOR IMPROVED VOC TREATMENT DEVICES - PHASE I  

EPA Science Inventory

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

241

Superior preclinical efficacy of gemcitabine developed as chitosan nanoparticulate system.  

PubMed

Gemcitabine, an anticancer nucleoside analogue, undergoes rapid enzymatic degradation following intravenous injection. This necessitates the administration of a high order of doses to observe a required therapeutic response, while such high doses result in significant side effects. To improve the intravenous delivery of gemcitabine and simultaneously enhance its antitumor activity, we have investigated its incorporation into a drug nanoplatform based on the biodegradable polymer chitosan. Two gemcitabine loading methods have been investigated: (i) entrapment into the polymeric network (entrapment procedure): drug incorporation prior to the coacervation process that leads to the formation of gemcitabine-loaded chitosan (GemChit) nanoparticles; and (ii) surface deposition onto already formed chitosan nanoparticles after incubation in gemcitabine solution (adsorption procedure). The former method produced much higher gemcitabine loading values and a sustained release profile. The main factors determining the gemcitabine loading and release kinetic have also been analyzed. Following intravenous injection, the GemChit formulation displayed a significantly improved antitumor activity comparatively to free gemcitabine, which was further confirmed by histology and immunohistochemistry studies, suggesting the potential of this chitosan-based gemcitabine nanomedicine for the effective treatment of tumors. PMID:21117615

Arias, José L; Reddy, L Harivardhan; Couvreur, Patrick

2011-01-10

242

Polymeric nanoparticulate system augmented the anticancer therapeutic efficacy of gemcitabine.  

PubMed

Gemcitabine hydrochloride is an anticancer nucleoside analogue indicated in clinic for the treatment of various solid tumors. Although this drug has been demonstrated to display anticancer activity against a wide variety of tumors, it is needed to be administered at high doses to elicit the required therapeutic response, simultaneously leading to severe adverse effects. We hypothesized that the efficient delivery of gemcitabine to tumors using a biodegradable carrier system could reduce the dose required to elicit sufficient therapeutic response. Thus, we have developed a nanoparticle formulation of gemcitabine suitable for parenteral administration based on the biodegradable polymer poly(octylcyanoacrylate) (POCA). The nanoparticles were synthesized by anionic polymerization of the corresponding monomer. Two drug loading methods were analyzed: the first one based on gemcitabine surface adsorption onto the preformed nanoparticles, and the second method being gemcitabine addition before the polymerization process leading to drug entrapment in the polymeric network. A detailed investigation of the capabilities of the polymer particles to load this drug is described. Gemcitabine entrapment into the polymer matrix yielded a higher drug loading and a slower drug release profile as compared with drug adsorption procedure. The main factors determining the gemcitabine incorporation to the polymer network were the nanoparticles preparation procedure, the monomer concentration, the surfactant concentration, the pH, and the drug concentration. The release kinetic of gemcitabine was found to be controlled by the pH and the type of drug incorporation. The cytotoxicity studies performed on L1210 tumor cells revealed a similar anticancer activity of the gemcitabine-loaded POCA (GPOCA) nanoparticle as free gemcitabine. Following intravenous administration into the mice bearing L1210 wt subcutaneous tumor, the GPOCA nanoparticles displayed significantly greater anticancer activity compared to free gemcitabine; this has been additionally confirmed by histology and immunohistochemistry studies, suggesting the potential of GPOCA for the efficient treatment of cancer. PMID:19694612

Arias, José L; Reddy, L Harivardhan; Couvreur, Patrick

2009-09-01

243

Psyllium arabinoxylan: Carboxymethylation, characterization and evaluation for nanoparticulate drug delivery.  

PubMed

The objective of present investigation was to optimize the interaction between carboxymethylated psyllium arabinoxylan and chitosan to prepare polyelectrolyte naoparticles for drug delivery applications. Arabinoxylan extracted from psyllium was carboxymethylated by reacting with monochloroacetic acid under alkaline conditions. Carboxymethylation of psyllium arabinoxylan was observed to increase its crystallinity, improve thermal stability and decrease the viscosity. Further, the effect of concentrations of carboxymethylated arabinoxylan and chitosan on the particle size and particle size distribution of ibuprofen loaded polyelectrolyte nanoparticles was screened using two-factor, three-level central composite experimental design. The results of optimization study revealed that the formation of nanometric polyelectrolyte is favored at the median level of carboxymethylated arabinoxylan and chitosan concentration. The optimal concentrations of carboxymethylated arabinoxylan and chitosan were found to be 0.0779% (w/v) and 0.0693% (w/v) respectively, which provided polyelectrolyte particles of size 337.2nm and polydispersity index 0.335. Further, polyelectrolyte complex nanoparticles were found to release ibuprofen over a prolonged period of 10h following Higuchi's square root release kinetics with the mechanism of release being combination of diffusion and erosion of matrix. PMID:25199870

Bhatia, Meenakshi; Ahuja, Munish

2015-01-01

244

Self assembled nanoparticulate Co:Pt for data storage applications  

Microsoft Academic Search

Nanoscale CoPt grains were prepared within protein shells from aqueous reactants. A series of particles with varying Co:Pt ratios was used to explore the transition from superparamagnetic to ferromagnetic behavior at room temperature. TEM and electron diffraction confirmed ordered fct CoPt phases with an average grain size of 4.1 nm. Magnetic characterization was performed at room temperature using VSM. The

Barnaby Warne; Oksana I. Kasyutich; Eric L. Mayes; Jason A. L. Wiggins; Kim K. W. Wong

2000-01-01

245

Nanoparticulate carriers: an emerging tool for breast cancer therapy.  

PubMed

Abstract Breast cancer is a leading cause of death for woman in the world. Cancer has the potential to spread to different organs around the body, and form metastases that can even develop after surgical removal of the primary tumour. Nanotechnology offers new promising strategies for the treatment of breast cancer, and has emerged as a powerful tool for fighting cancer. Nanoparticles can be fabricated to perform more than one task simultaneously, and can have a number of roles, such as acting as a therapeutic agent, drug delivery vehicle and/or tumour imaging agent. This review will focus on various forms of nanoparticles serving as potential agents for cancer therapeutics, illustrating their use in breast cancer therapies. This article also highlights the properties, current progress in the design and engineering of nanoparticles. PMID:25230853

Tharkar, Priyanka; Madani, Asad Ullah; Lasham, Annette; Shelling, Andrew N; Al-Kassas, Raida

2015-02-01

246

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. PMID:22496608

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

2012-01-01

247

Thick film magnetic nanoparticulate composites and method of manufacture thereof  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

248

Surface photochemistry of CO adsorbed on alumina supported nanoparticulate platinum.  

PubMed

Laser induced desorption of CO adsorbed on platinum nanoparticles on an epitaxial alumina support grown on NiAl(110) is reported for nanosecond laser excitation at ? = 355 nm. The nominal amount of platinum deposited was 0.1 nm, resulting in platinum particles with an average diameter of a few nanometres. The laser fluence was systematically varied between 6.4 and 25.5 mJ cm (- 2) per pulse. Fourier transform infrared reflection absorption spectra have been recorded as a function of CO coverage, the laser fluence and the number of photons impinging on the surface. Laser desorption is observed, in contrast to the case for experiments on Pt(111) for the same laser wavelength. For laser fluences below 12.7  mJ cm (- 2) per pulse, a cross section of (1.1 ± 0.2) × 10 (- 19) cm(2) can be estimated from the measurements. At elevated fluences a second desorption channel occurs with a cross section more than an order of magnitude larger, scaling linearly with the laser fluence. In all cases desorption ends at a critical coverage beyond which no desorption occurs and which depends on the laser fluence. Laser induced particle morphology changes are observed for higher laser fluences which are not apparent for bare particles. A model implying energy pooling within adsorbates at hot spots and even spillover between the metal nanoparticles and the oxidic support is discussed. Implications for the design of photocatalysts with possible use in chemical solar energy conversion are pointed out. PMID:21389387

Al-Shemmary, A; Buchwald, R; Al-Shamery, K

2010-03-01

249

Research Directions in Emergency Medicine  

Microsoft Academic Search

From the Research Directions Conference, Atlanta, January 1995. This Consensus document is being published simultaneously in Academic Emergency Medicine, American Journal of Emergency Medicine, Annals of Emergency Medicine, and Journal of Emergency Medicine.[Research Directions Conference: Research directions in emergency medicine. Ann Emerg Med March 1996;27:339-342.

Richard V Aghababian; William G Barsan; William H Bickell; Michelle H Biros; Charles G Brown; Charles B Cairns; Michael L Callaham; Donna L Carden; William H Cordell; Richard C Dart; Steven C Dronen; Herbert G Garrison; Lewis R Goldfrank; Jerris R Hedges; Gabor D Kelen; Arthur L Kellermann; Lawrence M Lewis; Robert J Lewis; Louis J Ling; John A Marx; John B McCabe; Arthur B Sanders; David L Schriger; David P Sklar; Terrence D Valenzuela; Joseph F Waeckerle; Robert L Wears; J. Douglas White; Robert J Zalenski

1996-01-01

250

Determinants of molecular motor directionality  

Microsoft Academic Search

Work over the past two years has led to a breakthrough in our understanding of the molecular basis of the directionality of the kinesin motor proteins. This breakthrough has come first from the reversal of directionality of the kinesin-related motor Ncd, followed closely by the reversal of kinesin’s directionality and the finding that the Ncd ‘neck’ can convert Ncd or

Sharyn A. Endow

1999-01-01

251

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

252

Evaluation of Direct Instruction Implementations.  

ERIC Educational Resources Information Center

Defines four broad roles of measurement in Direct Instruction. Describes how to make effective use of assessments that are integrated into Direct Instruction programs and how to plan and implement evaluation of the broad outcomes for Direct Instruction programs. Discusses assessment, evaluation, and validity; formative evaluation; summative…

Slocum, Timothy A.

2003-01-01

253

Foreign Direct Investments to Bulgaria  

Microsoft Academic Search

Direct investment in the country is an international investment, in which the direct investor, resident of a foreign economy, acquires a lasting interest (at least 10 % of the equity) in an enterprise resident of the Bulgarian economy (direct investment enterprise). There are two main cases of equity investment as follows: privatization and other transactions. In Bulgaria government economic policies

Stefan Petranov

2003-01-01

254

AUTHORIZATION AGREEMENT PAYROLL DIRECT DEPOSIT  

E-print Network

1 AUTHORIZATION AGREEMENT FOR PAYROLL DIRECT DEPOSIT Graduate Undergraduate Class year authorize the deposit of my Wesleyan University Payroll Check/Earnings into my Bank Account as indicated below. I understand that I must complete a new direct deposit authorization to stop direct deposit

Royer, Dana

255

Using directionality in mobile routing  

Microsoft Academic Search

The increased usage of directional methods of commu- nications has prompted research into leveraging direction- ality in every layer of the network stack. In this paper, we explore the use of directionality in layer 3 to facilitate routing in highly mobile environments. We introduce Mo- bile Orthogonal Rendezvous Routing Protocol (MORRP), a lightweight, but scalable routing protocol utilizing di- rectional

Bow-Nan Cheng; Murat Yuksel; Shivkumar Kalyanaraman

2010-01-01

256

Motor directional tuning across brain areas: directional resonance and the role of inhibition for directional accuracy  

PubMed Central

Motor directional tuning (Georgopoulos et al., 1982) has been found in every brain area in which it has been sought for during the past 30-odd years. It is typically broad, with widely distributed preferred directions and a population signal that predicts accurately the direction of an upcoming reaching movement or isometric force pulse (Georgopoulos et al., 1992). What is the basis for such ubiquitous directional tuning? How does the tuning come about? What are the implications of directional tuning for understanding the brain mechanisms of movement in space? This review addresses these questions in the light of accumulated knowledge in various sub-fields of neuroscience and motor behavior. It is argued (a) that direction in space encompasses many aspects, from vision to muscles, (b) that there is a directional congruence among the central representations of these distributed “directions” arising from rough but orderly topographic connectivities among brain areas, (c) that broad directional tuning is the result of broad excitation limited by recurrent and non-recurrent (i.e., direct) inhibition within the preferred direction loci in brain areas, and (d) that the width of the directional tuning curve, modulated by local inhibitory mechanisms, is a parameter that determines the accuracy of the directional command. PMID:23720612

Mahan, Margaret Y.; Georgopoulos, Apostolos P.

2013-01-01

257

[Advance medical directives].  

PubMed

A patient's rights to autonomy and to participate in the decision making process is a fundamental ethical principle. However, for the non-competent patient, participation in decision-making is more problematic. A survey carried out in Israel found that less than half of the offspring of terminally ill elderly patients knew the request of their parents regarding life-supporting measures. A solution to this problem is the use of medical advance directives (MADs). In the U.S.A (in 1991) it was required by a federal law to inform every hospitalized patient of his right to use MADs. The experience from the use of MADs in the USA during the last 10 years show that: 1) Most lay persons as well as medical staff support the use of MADs 2) The rate of the use of MADs is about 20%, and among long term care hospitalized patients it is even higher. 3) Sex, age, level of education, morbidity and income were found to be significant factors. 4) Education on the use of the MADs raised the rate of use. 5) Most of the patients who had MADs did not discuss the issue of life supporting treatment with their physicians. 6) Patients who had MADs received less aggressive treatment with reduced medical cost. 7) There is a preference to write generic MADs. Arguments supporting the use of MADs state that they: extend patient autonomy; relieve patient anxiety regarding unwanted treatment; relieve physicians' anxiety concerning legal liability; reduce interfamily conflicts, and they also lower health care costs. Arguments opposing the use claim that they: violate sanctity of life; promote an adversarial physician-patient relationship; may lead to euthanasia; fail to express the patient's current wishes and may even counteract physicians' values. On the basis of experience in the USA and the positive attitude regarding MADs, it appears that MADs can also be applicable in Israel. PMID:11905092

Sonnenblick, Moshe

2002-02-01

258

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

Federal Register 2010, 2011, 2012, 2013

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

2013-05-30

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

For directions go to: www.rowan.edu/directions  

E-print Network

For directions go to: www.rowan.edu/directions Academics Students have access to the resources and the student/faculty ratio is 15 to 1. The University offers 80 undergraduate majors among seven colleges Business, Communication, Education, Engineering, Fine & Performing Arts, Liberal Arts & Sciences

Rusu, Adrian

261

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

262

Directed Discovery of Crystal Structures  

NSDL National Science Digital Library

David Mogk and Kent Ratajeski Department of Earth Sciences, Montana State University, Bozeman, MT Published Jan. 25, 2005 Description This contribution is modified from a published exercise "Directed ...

263

Scatterometer directional response during rain  

NASA Technical Reports Server (NTRS)

Rainfall modification of directional scatterometer response from the sea surface was simulated in wind-wave tank experiments. Data show that for the range of conditions in laboratory experiments, rain enhances radar cross section for all azimuthal angles relative to wind direction. This result broadens previous measurements, which showed that scatterometer response increases with increasing rainfall for radars pointing upwind. But more to the point, the data also show that the directional dynamic-range of scatterometry diminishes rapidly as rainfall rate increases. Thus, while it may be possible to determine wind speed and direction during rain, it will require adequate system sensitivity.

Bliven, L.; Norcross, G.; Giovanangeli, J.-P.

1989-01-01

264

Laser Direct Drive: Scientific Advances,  

E-print Network

#12;14 Laser driven instabilities cause problems: Produces high energy electrons that preheat DT fu1 Laser Direct Drive: Scientific Advances, Technical Achievements, and the Road To Fusion Energy Presented by John Sethian Naval Research Laboratory #12;2 Fusion Energy with Lasers and Direct Drive

265

Optically broadcasting wind direction indicator  

NASA Technical Reports Server (NTRS)

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. (inventor)

1994-01-01

266

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 direct…

Thaheem, A. B.

2005-01-01

267

Direct photon production at RHIC  

NASA Astrophysics Data System (ADS)

Direct photon yields in Au+Au collisions at ?sNN = 200 GeV have been measured by the PHENIX experiment at RHIC, and we report recent results. Direct photons are produced in the initial hard partonic scatterings, are not affected by the strong interaction, and can be described by perturbative QCD. Consequently, they are offer a powerful probe of the nature of the produced medium. We have reported that the nuclear modification factor RAA of direct photon yield is one in the high-pT region above 5 GeV/c [1]. This means that scaling works well at high pT, and it indicates that the high-pT direct photon yield is hard-scattering dominant. At low-pT region of 1< pT <3 GeV/c, the yield of direct photons has been recently measured with the internal conversion method. At low pT, the large excess of direct photon yield is observed, and the excess of the yield is larger than that in d+Au collisions. Furthermore, we have measured the azimuthal anisotropy ?2 of direct photons, which can provide a glimpse of the early space-time evolution in the collision. The result of our measurements clearly shows that the ?2 of direct photon yield has positive value at low pT, while it is zero at high pT.

Aramaki, Y.; Collaboration, Phenix

2012-09-01

268

Explosive Percolation in Directed Networks  

E-print Network

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

Anlage, Steven

269

Epidemic threshold in directed networks.  

PubMed

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

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

2013-12-01

270

Defense Nuclear Agency (DNA). Directive  

SciTech Connect

Under the authority vested in the Secretary of Defense by Title 10, United States Code, the Directive reissues DoD Directive 5105.31, November 3, 1971, to update the responsibilities, functions, relationship, and authorities of the Defense Nuclear Agency.

Furtner, R.

1987-03-18

271

Directions in Center Director Training  

ERIC Educational Resources Information Center

Exchange invited some of the leading trend watchers in the arena of director training to share their insights on the current state and future directions in this country. This article presents the authors' insights on the directions in center director training. They also share their views on whether the amount of and quality of training out there…

Bloom, Paula Jorde; Vinci, Yasmina; Rafanello, Donna; Donohue, Chip

2011-01-01

272

Directivity function of muon detector  

NASA Astrophysics Data System (ADS)

We introduce a new concept of directivity function (DF) to describe directional sensitivity of a particle detector. DF is ? 3D function, describing the sensitivity of a detector to asymptotic directions of primary protons. It defines the contribution of primary protons, arriving from different asymptotic directions to the count rate of the detector. We develop the approach for computing the DF and derive it in particular case of SEVAN muon detector, located at mount Aragats, Armenia. Obtained data enable one to outline the region of solid angles, inside of which the arriving protons contribute a given percentage of count rate. In general, the DF can have the multi peak shape. It provides the most detailed and accurate description of directional sensitivity of a particle detector and we suggest that it is used in space research based on neutron and muon detectors.

Karapetyan, G. G.

2015-02-01

273

Directed Surfaces in Disordered Media  

NASA Astrophysics Data System (ADS)

The critical exponents for a class of one-dimensional models of interface depinning in disordered media can be calculated through a mapping onto directed percolation (DP)(A.-L. Barabási and H.E. Stanley, Fractal Concepts in Surface Growth) (Cambridge University Press, Cambridge, 1995); S.V. Buldyrev et al., Phys. Rev. A 45, R8313 (1992); L.-H. Tang and H. Leschhorn, Phys. Rev. A 45, R8309 (1992).. In higher dimensions these models give rise to directed surfaces, which do not belong to the directed percolation universality class. We formulate a scaling theory of directed surfaces, and calculate critical exponents numerically, using a cellular automaton that locates the directed surfaces without making reference to the dynamics of the underlying interface growth models.

Barabási, Albert-László; Grinstein, G.; Muñoz, M.

1996-03-01

274

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

275

75 FR 53611 - Direct Investment Surveys: BE-577, Quarterly Survey of U.S. Direct Investment Abroad-Direct...  

Federal Register 2010, 2011, 2012, 2013

...Direct Investment Abroad--Direct Transactions...Reporter With Foreign Affiliate...of U.S. Direct Investment Abroad...Reporter With Foreign Affiliate...of U.S. Direct Investment Abroad...Reporter With Foreign...

2010-09-01

276

Direct Manipulation in Virtual Reality  

NASA Technical Reports Server (NTRS)

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

Bryson, Steve

2003-01-01

277

Potential Theory for Directed Networks  

PubMed Central

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; Lü, Linyuan; Wang, Wen-Qiang; Zhou, Tao

2013-01-01

278

Directional Summation in Non-direction Selective Retinal Ganglion Cells  

PubMed Central

Retinal ganglion cells receive inputs from multiple bipolar cells which must be integrated before a decision to fire is made. Theoretical studies have provided clues about how this integration is accomplished but have not directly determined the rules regulating summation of closely timed inputs along single or multiple dendrites. Here we have examined dendritic summation of multiple inputs along On ganglion cell dendrites in whole mount rat retina. We activated inputs at targeted locations by uncaging glutamate sequentially to generate apparent motion along On ganglion cell dendrites in whole mount retina. Summation was directional and dependent13 on input sequence. Input moving away from the soma (centrifugal) resulted in supralinear summation, while activation sequences moving toward the soma (centripetal) were linear. Enhanced summation for centrifugal activation was robust as it was also observed in cultured retinal ganglion cells. This directional summation was dependent on hyperpolarization activated cyclic nucleotide-gated (HCN) channels as blockade with ZD7288 eliminated directionality. A computational model confirms that activation of HCN channels can override a preference for centripetal summation expected from cell anatomy. This type of direction selectivity could play a role in coding movement similar to the axial selectivity seen in locust ganglion cells which detect looming stimuli. More generally, these results suggest that non-directional retinal ganglion cells can discriminate between input sequences independent of the retina network. PMID:23516351

Abbas, Syed Y.; Hamade, Khaldoun C.; Yang, Ellen J.; Nawy, Scott; Smith, Robert G.; Pettit, Diana L.

2013-01-01

279

Directional summation in non-direction selective retinal ganglion cells.  

PubMed

Retinal ganglion cells receive inputs from multiple bipolar cells which must be integrated before a decision to fire is made. Theoretical studies have provided clues about how this integration is accomplished but have not directly determined the rules regulating summation of closely timed inputs along single or multiple dendrites. Here we have examined dendritic summation of multiple inputs along On ganglion cell dendrites in whole mount rat retina. We activated inputs at targeted locations by uncaging glutamate sequentially to generate apparent motion along On ganglion cell dendrites in whole mount retina. Summation was directional and dependent13 on input sequence. Input moving away from the soma (centrifugal) resulted in supralinear summation, while activation sequences moving toward the soma (centripetal) were linear. Enhanced summation for centrifugal activation was robust as it was also observed in cultured retinal ganglion cells. This directional summation was dependent on hyperpolarization activated cyclic nucleotide-gated (HCN) channels as blockade with ZD7288 eliminated directionality. A computational model confirms that activation of HCN channels can override a preference for centripetal summation expected from cell anatomy. This type of direction selectivity could play a role in coding movement similar to the axial selectivity seen in locust ganglion cells which detect looming stimuli. More generally, these results suggest that non-directional retinal ganglion cells can discriminate between input sequences independent of the retina network. PMID:23516351

Abbas, Syed Y; Hamade, Khaldoun C; Yang, Ellen J; Nawy, Scott; Smith, Robert G; Pettit, Diana L

2013-01-01

280

Directional hearing: from biophysical binaural cues to directional hearing outdoors.  

PubMed

When insects communicate by sound, or use acoustic cues to escape predators or detect prey or hosts they have to localize the sound in most cases, to perform adaptive behavioral responses. In the case of particle velocity receivers such as the antennae of mosquitoes, directionality is no problem because such receivers are inherently directional. Insects equipped with bilateral pairs of tympanate ears could principally make use of binaural cues for sound localization, like all other animals with two ears. However, their small size is a major problem to create sufficiently large binaural cues, with respect to both interaural time differences (ITDs, because interaural distances are so small), but also with respect to interaural intensity differences (IIDs), since the ratio of body size to the wavelength of sound is rather unfavorable for diffractive effects. In my review, I will only shortly cover these biophysical aspects of directional hearing. Instead, I will focus on aspects of directional hearing which received relatively little attention previously, the evolution of a pressure difference receiver, 3D-hearing, directional hearing outdoors, and directional hearing for auditory scene analysis. PMID:25231204

Römer, Heiner

2015-01-01

281

Directional impedance of geared transmissions  

E-print Network

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

Wang, Albert Duan

2012-01-01

282

Direct Broadcast Satellite: Radio Program  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

283

New Directions in Immigration History.  

ERIC Educational Resources Information Center

Defines new directions that immigration history has taken in the 1980s, and indicates areas in which further work should be done. A variety of subjects are discussed - from recent immigration arrivals to new methods of historical data collection. (BSR)

Seller, Maxine S.

1987-01-01

284

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

285

Directions.  

ERIC Educational Resources Information Center

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

Manning, Helen H.

286

Directional microwave applicator and methods  

NASA Technical Reports Server (NTRS)

A miniature microwave antenna is disclosed which may be utilized for biomedical applications such as, for example, radiation induced hyperthermia through catheter systems. One feature of the antenna is that it possesses azimuthal directionality despite its small size. This directionality permits targeting of certain tissues while limiting thermal exposure of adjacent tissue. One embodiment has an outer diameter of about 0.095'' (2.4 mm) but the design permits for smaller diameters.

Fink, Patrick W. (Inventor); Lin, Greg Y. (Inventor); Chu, Andrew W. (Inventor); Dobbins, Justin A. (Inventor); Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor)

2008-01-01

287

Nuclear astrophysics from direct reactions  

E-print Network

Accurate nuclear reaction rates are needed for primordial nucleosynthesis and hydrostatic burning in stars. The relevant reactions are extremely difficult to measure directly in the laboratory at the small astrophysical energies. In recent years direct reactions have been developed and applied to extract low-energy astrophysical S-factors. These methods require a combination of new experimental techniques and theoretical efforts, which are the subject of this presentation.

C. A. Bertulani

2009-01-22

288

Examined the direct carburizing method  

SciTech Connect

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

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

1995-12-31

289

Optimal Traversal of Directed Hypergraphs  

Microsoft Academic Search

A directed hypergraph is defined by a set of nodes and a set of hyperarcs, each connecting aset of source nodes to a single target node. Directed hypergraphs are used in several contexts tomodel different combinatorial structures, such as functional dependencies [Ull82], Horn clauses inpropositional calculus [AI91], AND-OR graphs [Nil82], Petri nets [Pet62]. A hyperpath, similarlyto the notion of path

Giorgio Ausiello; Roberto Giaccio; Giuseppe F. Italiano; Umberto Nanni

1992-01-01

290

Asymmetric Wettability Directs Leidenfrost Droplets  

SciTech Connect

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

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

2014-01-01

291

Magnetic inelastic dark matter: Directional signals without a directional detector  

NASA Astrophysics Data System (ADS)

The magnetic inelastic dark matter (MiDM) model, in which dark matter inelastically scatters off nuclei through a magnetic dipole interaction, has previously been shown to reconcile the DAMA/LIBRA annual modulation signal with null results from other experiments. In this work, we explore the unique directional detection signature of MiDM. After the dark matter scatters into its excited state, it decays with a lifetime of order 1?s and emits a photon with energy ˜100keV. Both the nuclear recoil and the corresponding emitted photon can be detected by studying delayed coincidence events. The recoil track and velocity of the excited state can be reconstructed from the nuclear interaction vertex and the photon event vertex. The angular distribution of the WIMP recoil tracks is sharply peaked and modulates daily. It is therefore possible to observe the directional modulation of WIMP-nucleon scattering without a large-volume gaseous directional detection experiment. Furthermore, current experiments such as XENON100 can immediately measure this directional modulation and constrain the MiDM parameter space with an exposure of a few thousand kg·day.

Lin, Tongyan; Finkbeiner, Douglas P.

2011-04-01

292

A Cell's Sense of Direction  

NSDL National Science Digital Library

In eukaryotic cells directional sensing is mediated by heterotrimeric guanine nucleotideâÂÂbinding protein (G protein)âÂÂlinked signaling pathways. In Dictyostelium discoideum amoebae and mammalian leukocytes, the receptors and G-protein subunits are uniformly distributed around the cell perimeter. Chemoattractants induce the transient appearance of binding sites for several pleckstrin homology domainâÂÂcontaining proteins on the inner face of the membrane. In gradients of attractant these sites are persistently present on the side of the cell facing the higher concentration, even in the absence of a functional actin cytoskeleton or cell movement. Thus, the cell senses direction by spatially regulating the activity of the signal transduction pathway.

Carole A. Parent (Johns Hopkins University School of Medicine;Department of Biological Chemistry); Peter N. Devreotes (Johns Hopkins University School of Medicine;Department of Biological Chemistry)

1999-04-30

293

Biocatalyst Development by Directed Evolution  

PubMed Central

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

Wang, Meng; Si, Tong; Zhao, Huimin

2012-01-01

294

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

295

Verification of the directivity index and other measures of directivity in predicting directional benefit  

NASA Astrophysics Data System (ADS)

The relationship between various directivity measures and subject performance with directional microphone hearing aids was determined. Test devices included first- and second-order directional microphones. Recordings of sentences and noise (Hearing in Noise Test, HINT) were made through each test device in simple, complex, and anisotropic background noise conditions. Twenty-six subjects, with normal hearing, were administered the HINT test recordings, and directional benefit was computed. These measures were correlated to theoretical, free-field, and KEMAR DI values, as well as front-to-back ratios, in situ SNRs, and a newly proposed Db-SNR, wherein a predictive value of the SNR improvement is calculated as a function of the noise source incidence. The different predictive scores showed high correlation to the measured directional benefit scores in the complex (diffuse-like) background noise condition (r=0.89-0.97, p<0.05) but not across all background noise conditions (r=0.45-0.97, p<0.05). The Db-SNR approach and the in situ SNR measures provided excellent prediction of subject performance in all background noise conditions (0.85-0.97, p<0.05) None of the predictive measures could account for the effects of reverberation on the speech signal (r=0.35-0.40, p<0.05).

Dittberner, Andrew; Bentler, Ruth

2005-09-01

296

Axiom directed Focusing long version  

E-print Network

Axiom directed Focusing long version Cl´ement Houtmann Universit´e Henri Poincar´e Nancy 1 & LORIA of computational and reasoning axioms. Although soundness is ensured, using superdeduction and deduction modulo that some hypotheses on the synchrony of reasoning axioms are verified. It implies that cut- elimination

Paris-Sud XI, Université de

297

Wimp/Neutralino Direct Detection  

E-print Network

The most popular candidate for non baryonic dark matter is the neutralino. More than twenty experiments are dedicated to its direct detection. This review describes the most competitive and promising experiments with different detection techniques. The most recent results are presented with some prospects for the near future.

M. De Jesus

2004-02-02

298

Direction of automobile power's development  

Microsoft Academic Search

In 2009, the automobile sales in China have reached 13.7 million. China has been the oil import country for many years. So, the research about the direction of automobile power's development is related to the safety of Chinese economy. In this paper, we have compared all kinds of electric automobiles' main cost performance and influence on the environment. And we

Jiabin Tong; Yujun Bao

2010-01-01

299

Directions for Defense Digital Libraries.  

ERIC Educational Resources Information Center

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

Larsen, Ronald L.

1998-01-01

300

Future Directions for Magnetic Sensors  

E-print Network

Future Directions for Magnetic Sensors: HYBRIDMATERIALS Our goal is to develop the scientific expertise needed to allow modeling and simulation to become the driving force in improving magnetic sensors effectiveness in developing new and improved magnetic sensors. By quantifying the improvement in sensor

301

Direction discriminating hearing aid system  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

302

Direct from CDC Environmental Health  

E-print Network

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

303

Direct from CDC Environmental Health  

E-print Network

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

304

Direct from CDC Environmental Health  

E-print Network

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

305

Direct from CDC Environmental Health  

E-print Network

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

306

Dissociative Style and Directed Forgetting  

Microsoft Academic Search

Dissociative style may correspond to an enhanced ability to avoid conscious recollection of traumatic experiences, which may, however, remain dormant in nonconscious memory. This hypothesis was tested in two “directed-forgetting” experiments with affectively neutral words (experiment 1) and sex and threat words (experiment 2) employing students high and low in dissociative style, and dissociative patients. Conscious and nonconscious memory were

Bernet M. Elzinga; Edwin de Beurs; Joseph A. Sergeant; Richard Van Dyck; R. Hans Phaf

2000-01-01

307

Directional Dependence in Developmental Research  

ERIC Educational Resources Information Center

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

von Eye, Alexander; DeShon, Richard P.

2012-01-01

308

Liquid Hydrogen Strategic Directions for  

E-print Network

Liquid Hydrogen Delivery Strategic Directions for Hydrogen Delivery Workshop May 7-8, 2003 Crystal even with incremental technology Group a little light on technical expertise, but feel captured main technology Relatively mature field of study ­ government funding needed for incremental improvements

309

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

310

Direction of First Aid Kit  

E-print Network

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

Natelson, Douglas

311

Reflections, Perceptions, and Future Directions.  

ERIC Educational Resources Information Center

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

Renzulli, Joseph S.

1999-01-01

312

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

313

Direct simulation of turbulent combustion  

NASA Technical Reports Server (NTRS)

Understanding and modeling of turbulent combustion are key problems in the computation of numerous practical systems. Because of the lack of analytical theories in this field and of the difficulty of performing precise experiments, direct simulation appears to be one of the most attractive tools to use in addressing this problem. From Sep. 1989 - Sep. 1990, the following problems were studied using direct simulation but also experiments and theoretical models: (1) the influence of curvature on premixed flame fronts; (2) the construction of a model for the flame stretch based on direct simulation and multifractal analysis; and (3) the simulation of the interaction between random flow field and a flame front. The general objective was to improve knowledge of turbulent combustion but also to use this information for turbulent combustion models. The transfer of direct simulation results towards models is also in progress. A submodel to evaluate the flame stretch was derived from the present study and incorporated in the Coherent Flame model used in France for piston and aircraft engines.

Poinsot, Thierry J.

1991-01-01

314

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. PMID:16148303

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

2005-01-01

315

pressing ahead in new directions  

E-print Network

medication errors and adverse events occur in hospitals and in the community? We could apply this knowledge and administrative leaders who command an exceptional breadth of expertise. In our diversity, we share the common and novel therapies... " In our dive directions OUR FACULTY AND ADMINISTRATIVE LEADERS: Susan Abby Dale

Lim, Wendell

316

Oriented matrix promotes directional tubulogenesis.  

PubMed

Detailed control over the structural organization of scaffolds and engineered tissue constructs is a critical need in the quest to engineer functional tissues using biomaterials. This work presents a new approach to spatially direct endothelial tubulogenesis. Micropatterned fibronectin substrates were used to control lung fibroblast adhesion and growth and the subsequent deposition of fibroblast-derived matrix during culture. The fibroblast-derived matrix produced on the micropatterned substrates was tightly oriented by these patterns, with an average variation of only 8.5°. Further, regions of this oriented extracellular matrix provided directional control of developing endothelial tubes to within 10° of the original micropatterned substrate design. Endothelial cells seeded directly onto the micropatterned substrate did not form tubes. A metric for matrix anisotropy showed a relationship between the fibroblast-derived matrix and the endothelial tubes that were subsequently developed on the same micropatterns with a resulting aspect ratio over 1.5 for endothelial tubulogenesis. Micropatterns in "L" and "Y" shapes were used to direct endothelial tubes to turn and branch with the same level of precision. These data demonstrate that anisotropic fibroblast-derived matrices instruct the alignment and shape of endothelial tube networks, thereby introducing an approach that could be adapted for future design of microvascular implants featuring organ-specific natural matrix that patterns microvascular growth. PMID:25219769

Soucy, Patricia A; Hoh, Maria; Heinz, Will; Hoh, Jan; Romer, Lewis

2015-01-01

317

Direct solar-pumped lasers  

NASA Technical Reports Server (NTRS)

The feasibility of direct solar pumping of an iodine photodissociation laser at lambda = 1.315 microns was investigated. Threshold inversion density and effect of elevated temperature (up to 670 K) on the laser output were measured. These results and the concentration of solar radiation required for the solar pumped iodine laser are discussed.

Lee, J. H.; Shiu, Y. J.; Weaver, W. R.

1980-01-01

318

High-directivity acoustic antenna  

NASA Technical Reports Server (NTRS)

Acoustic antenna with unique electronic steering control is used to identify and define aerodynamic noise sources in free field, particularly in wind tunnel which is quite reverberant. Provision is made for high directivity as well as improved discrimination against unwanted background noise such as reverberation or echoes.

El-Sum, H. M. A.

1974-01-01

319

Duplex Direct Data Distribution System  

NASA Technical Reports Server (NTRS)

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 distribution or D3 (pronounced "D-cubed"). Commercially provided D3 will make it possible to download a data set from a spacecraft, like the International Space Station. as easily as one can extract a file from a remote server today, using a file transfer protocol. In a second category, NASA spacecraft will make use of commercial satellite communication (SATCOM) systems. Some of those services will come from purchasing time on unused transponders that cover landmasses. While it is likely there will be gaps in service coverage, Internet services should be available using these systems. This report addresses alternative methods of implementing a full duplex enhancement of the GRC developed experimental Ka-Band Direct Data Distribution (D3) space-to-ground communication link. The resulting duplex version is called the Duplex Direct Data Distribution (D4) system. The D4 system is intended to provide high-data-rate commercial direct or internet-based communications service between the NASA spacecraft in low earth orbit (LEO) and the respective principal investigators associated with these spacecraft. Candidate commercial services were assessed regarding their near-term potential to meet NASA requirements. Candidates included Ka-band and V-band geostationary orbit and non-geostationary orbit satellite relay services and direct downlink ("LEO teleport") services. End-to-end systems concepts were examined and characterized in terms of alternative link layer architectures. Alternatives included a Direct Link, a Relay Link, a Hybrid Link, and a Dual Mode Link. The direct link assessment examined sample ground terminal placements and antenna angle issues. The SATCOM-based alternatives examined existing or proposed commercial SATCOM services that could be available in the 2005 time frame. The alternatives were evaluated and compared in terms of average daily system throughput and cost per bit. Throughput was estimated based on hypothetical scenarios supporting the International Space Station and polar orbiting missions. The feasibility of using standard TCP and a modified TCP was evaluated and risks were identified. An estimate of the TCP acknowledgment data rate required to support a return channel rate of 622 Mbps was developed using OPNET.

Greenfield, Israel (Technical Monitor)

2001-01-01

320

Advance Directives for Mental Health Treatment  

Microsoft Academic Search

Advance directives are designed to establish a person's preferences for treatment if the person becomes incompetent in the future or unable to communicate those preferences to treatment providers. Mental health advance directives are similar to the more commonly used directives for end-of-life medical decisions. A patient must be competent to execute a mental health advance directive, and the directive must

Debra S. Srebnik; John Q. La Fond

321

Sampling properties of directed networks.  

PubMed

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. PMID:23214649

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

2012-10-01

322

Direct detection of dark matter axions with directional sensitivity  

SciTech Connect

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

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

2012-10-01

323

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Directional antennas. 101.115 Section 101.115 ...Standards § 101.115 Directional antennas. (a) Unless otherwise authorized...of this part must employ a directional antenna adjusted with the center of the...

2013-10-01

324

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Directional antennas. 101.115 Section 101.115 ...Standards § 101.115 Directional antennas. (a) Unless otherwise authorized...of this part must employ a directional antenna adjusted with the center of the...

2010-10-01

325

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

326

Ultra-wideband directional sampler  

DOEpatents

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

McEwan, T.E.

1996-05-14

327

Ultra-wideband directional sampler  

DOEpatents

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

McEwan, Thomas E. (Livermore, CA)

1996-01-01

328

OM300 Direction Drilling Module  

SciTech Connect

OM300 – Geothermal Direction Drilling Navigation Tool: Design and produce a prototype directional drilling navigation tool capable of high temperature operation in geothermal drilling Accuracies of 0.1° Inclination and Tool Face, 0.5° Azimuth Environmental Ruggedness typical of existing oil/gas drilling Multiple Selectable Sensor Ranges High accuracy for navigation, low bandwidth High G-range & bandwidth for Stick-Slip and Chirp detection Selectable serial data communications Reduce cost of drilling in high temperature Geothermal reservoirs Innovative aspects of project Honeywell MEMS* Vibrating Beam Accelerometers (VBA) APS Flux-gate Magnetometers Honeywell Silicon-On-Insulator (SOI) High-temperature electronics Rugged High-temperature capable package and assembly process

MacGugan, Doug

2013-08-22

329

Direct N-body Simulations  

E-print Network

Special high-accuracy direct force summation N-body algorithms and their relevance for the simulation of the dynamical evolution of star clusters and other gravitating N-body systems in astrophysics are presented, explained and compared with other methods. Other methods means here approximate physical models based on the Fokker-Planck equation as well as other, approximate algorithms to compute the gravitational potential in N-body systems. Questions regarding the parallel implementation of direct ``brute force'' N-body codes are discussed. The astrophysical application of the models to the theory of relaxing rotating and non-rotating collisional star clusters is presented, briefly mentioning the questions of the validity of the Fokker-Planck approximation, the existence of gravothermal oscillations and of rotation and primordial binaries.

R. Spurzem

1999-06-08

330

Azimuthal anisotropy of direct photons  

SciTech Connect

The electromagnetic bremsstrahlung produced by a quark interacting with nucleons or nuclei is azimuthally asymmetric. In the light-cone dipole approach this effect is related to the orientation dependent dipole cross section. Such a radiation anisotropy is expected to contribute to the azimuthal asymmetry of direct photons in pA and AA collisions, as well as in deep-inelastic scattering and in the production of dileptons.

Kopeliovich, B. Z. [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Joint Institute for Nuclear Research, Dubna (Russian Federation); Pirner, H. J. [Institute for Theoretical Physics, University of Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany); Rezaeian, A. H.; Schmidt, Ivan [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile)

2008-02-01

331

Pyramidal direct methanol fuel cells  

Microsoft Academic Search

The main concept of this article is to allow for the optimized tree-like design of the flow distributors to actually define the shape of the fuel cell, thereby eliminating problems associated with the mismatch between a predecided rectangular shape and a functionally preferred channel distribution system. The work focuses on direct methanol fuel cells (DMFC). A one-dimensional across-the-cell model is

S. M. Senn; D. Poulikakos

2006-01-01

332

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

333

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

334

Direct mediation, duality and unification  

NASA Astrophysics Data System (ADS)

It is well-known that in scenarios with direct gauge mediation of supersymmetry breaking the messenger fields significantly affect the running of Standard Model couplings and introduce Landau poles which are difficult to avoid. Among other things, this appears to remove any possibility of a meaningful unification prediction and is often viewed as a strong argument against direct mediation. We propose two ways that Seiberg duality can circumvent this problem. In the first, which we call ``deflected-unification'', the SUSY-breaking hidden sector is a magnetic theory which undergoes a Seiberg duality to an electric phase. Importantly, the electric version has fewer fundamental degrees of freedom coupled to the MSSM compared to the magnetic formulation. This changes the ?-functions of the MSSM gauge couplings so as to push their Landau poles above the unification scale. We show that this scenario is realised for recently suggested models of gauge mediation based on a metastable SCQD-type hidden sector directly coupled to MSSM. The second possibility for avoiding Landau poles, which we call ``dual-unification'', begins with the observation that, if the mediating fields fall into complete SU(5) multiplets, then the MSSM+messengers exhibits a fake unification at unphysical values of the gauge couplings. We show that, in known examples of electric/magnetic duals, such a fake unification in the magnetic theory reflects a real unification in the electric theory. We therefore propose that the Standard Model could itself be a magnetic dual of some unknown electric theory in which the true unification takes place. This scenario maintains the unification prediction (and unification scale) even in the presence of Landau poles in the magnetic theory below the GUT scale. We further note that this dual realization of grand unification can explain why Nature appears to unify, but the proton does not decay.

Abel, Steven; Khoze, Valentin V.

2008-11-01

335

Estimating Waveguide Feed Directivity and Spacing  

NASA Technical Reports Server (NTRS)

Approximate curves simplify initial steps of antenna design. Maximum achievable directivity exponents plotted as functions of element spacing in wavelengths for equilateral triangular array of rectangular waveguides. Directivities and exponents calculated for circular waveguides, pyramidal horns, and other standard feeds. Designer quickly estimates element spacing necessary to achieve required directivity or directivity achievable.

Rahmat-Samii, Y.; Cramer, P. W.; Woo, K. E.; Lee, S. W.

1983-01-01

336

Expanding Horizons in Self-Directed Learning.  

ERIC Educational Resources Information Center

The following papers are included: "Preface" (Huey B. Long); "Self-Directed Learning: Smoke and Mirrors?" (Huey B. Long); "From Self-Culture to Self-Direction: An Historical Analysis of Self-Directed Learning" (Amy D. Rose); "The Link between Self-Directed and Transformative Learning" (Jane Pilling-Cormick); "Learner Orientations among Baby…

Long, Huey B.; And Others

337

Future directions in aeropropulsion technology  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

338

Strategic Directions 2010-2012  

E-print Network

on improving undergraduate retention and education, raising KU’s scholarly and #31;#20; #20;#16;#31;#18;#23;#1;#29;#31;#28;)#25;#20; #1;#16;#27;#19;#1;#20;#27; "#31;#24;#27;#22;#1; #14;#1;#23;#16; #1;!#23;#20;#1;#31;#20; #28;"#31;#18;#20; #1;!#28;#1...;#16;#18;#18;#28;#26;#29;#25;#24; #23;#1;!#23;#20; #20;#1;#16;#27;#19;#1;#28;!#23;#20;#31;#1; critical priorities. This vision demands an alignment of the libraries’ strategic directions and goals to support the university. Accordingly, the plan includes new initiatives that address...

2009-11-01

339

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

340

Future direction in airline marketing  

NASA Technical Reports Server (NTRS)

The rapid growth and broadening of the air travel market, coupled with a more sophisticated consumer, will dramatically change airline marketing over the next decade. Discussed is the direction this change is likely to take and its implications for companies within the industry. New conceptualization approaches are required if the full potential of this expanding market is to be fully realized. Marketing strategies are developed that will enable various elements of the travel industry to compete not only against each other but also with other products that are competing for the consumer's discretionary income.

Colussy, D. A.

1972-01-01

341

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

342

Directional Solidification of Eutectic Ceramics  

NASA Technical Reports Server (NTRS)

Two major problems associated with structural ceramics are lack of damage tolerance and insufficient strength and creep resistance at very high temperatures of interest for aerospace application. This work demonstrated that the directionally solidified eutectics can have unique poly-phase microstructures and mechanical properties superior to either constituent alone. The constraining effect of unique eutectic microstructures result in higher resistance to slow crack growth and creep. Prospect of achieving superior properties through controlled solidification are presented and this technology can also be beneficial to produce new class of materials.

Sayir, Ali

2001-01-01

343

Direct Statistical Simulation of Climate  

NASA Astrophysics Data System (ADS)

Non-equilibrium statistical mechanics opens up the possibility of modeling climate directly,footnotetextE. N. Lorenz, The Nature and Theory of the General Circulation of the Atmosphere, vol. 218. World Meteorological Organization (1967). bypassing the traditional approach of accumulating statistics from lengthy numerical simulations. One way to implement such Direct Statistical Simulation (DSS) is by systematic expansion in equal-time cumulants.footnotetextJ. B. Marston, E. Conover, and T. Schneider, J. Atmos. Sci. 65, 1955 (2008). Essential physics of the general circulation can be illustrated with idealized 1- and 2-layer models of the atmosphere.footnotetextJ. B. Marston, Ann. Rev. Cond. Matt. Phys. 3, 285 (2012). A truncation at second order in the hierarchy of cumulants is equivalent to retaining the interaction between zonal mean flows and eddies. Eddy-eddy interactions appear at higher orders, but care must be taken to keep the higher-order expansions realizable with non-negative probability distribution functions. Live demonstrations of models, and their statistical mechanical solution, will be performed. Possible effects of polar amplification of warming, due to the melting of arctic sea ice, on the mid-latitude jet stream will be illustrated.

Marston, Brad

2013-03-01

344

Radial lean direct injection burner  

DOEpatents

A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of air passages extending axially in the burner tube configured to convey air flows from the inlet end to the outlet end; a plurality of fuel passages extending axially along the burner tube and spaced around the plurality of air passage configured to convey fuel from the inlet end to the outlet end; and a radial air swirler provided at the outlet end configured to direct the air flows radially toward the outlet end and impart swirl to the air flows. The radial air swirler includes a plurality of vanes to direct and swirl the air flows and an end plate. The end plate includes a plurality of fuel injection holes to inject the fuel radially into the swirling air flows. A method of mixing air and fuel in a burner of a gas turbine is also provided. The burner includes a burner tube including an inlet end, an outlet end, a plurality of axial air passages, and a plurality of axial fuel passages. The method includes introducing an air flow into the air passages at the inlet end; introducing a fuel into fuel passages; swirling the air flow at the outlet end; and radially injecting the fuel into the swirling air flow.

Khan, Abdul Rafey; Kraemer, Gilbert Otto; Stevenson, Christian Xavier

2012-09-04

345

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 itâs 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

346

Direct dating of human fossils.  

PubMed

The methods that can be used for the direct dating of human remains comprise of radiocarbon, U-series, electron spin resonance (ESR), and amino acid racemization (AAR). This review gives an introduction to these methods in the context of dating human bones and teeth. Recent advances in ultrafiltration techniques have expanded the dating range of radiocarbon. It now seems feasible to reliably date bones up to 55,000 years. New developments in laser ablation mass spectrometry permit the in situ analysis of U-series isotopes, thus providing a rapid and virtually non-destructive dating method back to about 300,000 years. This is of particular importance when used in conjunction with non-destructive ESR analysis. New approaches in AAR analysis may lead to a renaissance of this method. The potential and present limitations of these direct dating techniques are discussed for sites relevant to the reconstruction of modern human evolution, including Florisbad, Border Cave, Tabun, Skhul, Qafzeh, Vindija, Banyoles, and Lake Mungo. PMID:17103430

Grün, Rainer

2006-01-01

347

Direct visualization of magnetoelectric domains.  

PubMed

The coupling between the magnetic and electric dipoles in multiferroic and magnetoelectric materials holds promise for conceptually novel electronic devices. This calls for the development of local probes of the magnetoelectric response, which is strongly affected by defects in magnetic and ferroelectric ground states. For example, multiferroic hexagonal rare earth manganites exhibit a dense network of boundaries between six degenerate states of their crystal lattice, which are locked to both ferroelectric and magnetic domain walls. Here we present the application of a magnetoelectric force microscopy technique that combines magnetic force microscopy with in situ modulating high electric fields. This method allows us to image the magnetoelectric response of the domain patterns in hexagonal manganites directly. We find that this response changes sign at each structural domain wall, a result that is corroborated by symmetry analysis and phenomenological modelling, and provides compelling evidence for a lattice-mediated magnetoelectric coupling. The direct visualization of magnetoelectric domains at mesoscopic scales opens up explorations of emergent phenomena in multifunctional materials with multiple coupled orders. PMID:24292421

Geng, Yanan; Das, Hena; Wysocki, Aleksander L; Wang, Xueyun; Cheong, S-W; Mostovoy, M; Fennie, Craig J; Wu, Weida

2014-02-01

348

UROLOGIC ROBOTS AND FUTURE DIRECTIONS  

PubMed Central

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

Mozer, Pierre; Troccaz, Jocelyne; Stoianovici, Dan

2009-01-01

349

Staged direct injection diesel engine  

DOEpatents

A diesel engine having staged injection for using lower cetane number fuels than No. 2 diesel fuel. The engine includes a main fuel injector and a pilot fuel injector. Pilot and main fuel may be the same fuel. The pilot injector injects from five to fifteen percent of the total fuel at timings from 20.degree. to 180.degree. BTDC depending upon the quantity of pilot fuel injected, the fuel cetane number and speed and load. The pilot fuel injector is directed toward the centerline of the diesel cylinder and at an angle toward the top of the piston, avoiding the walls of the cylinder. Stratification of the early injected pilot fuel is needed to reduce the fuel-air mixing rate, prevent loss of pilot fuel to quench zones, and keep the fuel-air mixture from becoming too fuel lean to become effective. In one embodiment, the pilot fuel injector includes a single hole for injection of the fuel and is directed at approximately 48.degree. below the head of the cylinder.

Baker, Quentin A. (San Antonio, TX)

1985-01-01

350

Qualitative spatial reasoning for direction relation  

NASA Astrophysics Data System (ADS)

In geographic space, there are there main spatial relations among spatial entities, which are topological relation, direction relation and distance relation. Because spatial relation theories and researches directly influence the design, develop and application of GIS system, it attaches greatly importance to international GIS and interrelated academe. Qualitative spatial reasoning forms an important part of the commonsense reasoning required for building intelligent GIS. Because of the complexity and uncertainty inherent in spatial issues, the description and reasoning of spatial relation often use qualitative method in accordance with spatial cognition. Because direction relation is one of the most frequent qualitative spatial reasoning factors used in everyday life, the qualitative direction relation reasoning is a kind of important qualitative spatial reasoning. In this paper, we focus our efforts on the problem of reasoning the direction relation between regions that are composed of sets of polygons. According to the number of direction relation elements, direction relation can be divided into monomial direction relation (including one direction relation element only) and multinomial direction relation (including more than one direction relation elements); and the reference frame of direction relation can be divided into one reference frame and two reference frames. Previous methods always abstract regions into points or approximately equal in their size under two reference frames. In order to have meticulously reasoning results, we proposed a method of qualitative spatial reasoning for direction relation based on one reference frame under four different kinds of situations, that is monomial and monomial direction relation reasoning, multinomial and monomial direction relation reasoning, monomial and multinomial direction relation reasoning, multinomial and multinomial direction relation reasoning. In addition, a prototype system and a case study are carried out, and the future research problems and directions about qualitative spatial reasoning for direction relation are also discussed.

Chen, Penggen; Wu, Jing; Li, Dajun; Liu, Xingquan

2007-06-01

351

Direct measurement of MPD thrust  

NASA Technical Reports Server (NTRS)

An integrally mounted accelerometer has been used to obtain direct thrust measurements during operation of a magnetoplasmadynamic (MPD) thruster. The structural oscillations which can mask the accelerometer output have been ameliorated by stiffening the thruster to increase the lowest resonant frequency above the 1kHz region of interest. In addition, signal conditioning is used to provide a high signal-to-noise accelerometer output waveform. Impulse response measurement of the thruster frequency response function has proven to be an effective means of selecting the signal filter and estimating measurement errors. Comparison of the total impulse derived from the accelerometer output with that from a swinging arm thrust stand indicates 3 percent agreement, providing some confidence in the viability of the accelerometer thrust measurement technique.

Berg, J. M.; Kelly, A. J.; Jahn, R. G.

1984-01-01

352

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

2010-05-28

353

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

354

Direct electrochemistry of pentachlorophenol hydroxylase  

NASA Astrophysics Data System (ADS)

The direct electrochemistry of flavin-containing monooxygenase, pentachlorophenol hydroxlase (PCPH), has been investigated under a variety of conditions. PCPH underwent a two-electron process on the electrodes, which correspond to the reduction/oxidation of FAD/FADH2 within the enzyme. The electrochemical response of PCPH relies on the interface of the electrode and the enzyme solution. Three types of interaction of the enzyme molecule with the electrodes were observed: at a bare edge-plane graphite electrode, diffusion-controlled process was observed, suggesting the interaction is weak. In the presence of the cations, the interaction became stronger, so that the voltammetric response changed from a diffusion control to an adsorption control An intermediate case was observed at a poly(L- lysine) modified EPG electrode.

Xie, Wei-hong; Allen, H.; Hill, O.; Wong, Luet L.

2001-09-01

355

Multi-directional local search  

PubMed Central

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

Tricoire, Fabien

2012-01-01

356

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

357

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

2013-11-01

358

Directional solidification with heat losses  

NASA Astrophysics Data System (ADS)

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

Brattkus, K.; Davis, S. H.

1988-09-01

359

Direct Phasing of Nanocrystal Diffraction  

E-print Network

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, we develop an algorithm 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, our method imposes no constraints on the contrast other than positivity and works well at low resolution. We demonstrate successful reconstructions with simulated P1 lysozyme nanocrystal data down to a signal-to-noise ratio of 2 in the intensity gradients.

Elser, Veit

2013-01-01

360

Direct laser initiation of PETN  

SciTech Connect

In the early 1970s Yang and Menichelli demonstrated that direct laser illumination of low-density secondary explosive prr:ssings through a transparent window could produce detonation. 'The energy requirement for threshold initiation of detonation was reduced when a thin metal coating of metal covered the side of the window against which the low-density explosive was pressed. We have obtained experimental results that are in general agreement with the results of Renllund, Stanton and Trott (1 989) and recent: work by Nagayama, hou and Nakahara (2001). We report exploration of the effects of laser beam diameter, PEiTN density and specific surface area, and thickness of a titanium coating on the window.

Early, J. W. (James W.); Kennedy, J. E. (James E.)

2001-01-01

361

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

362

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

363

Directional Properties of Infragravity Waves  

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

364

Advance directives for mental health treatment.  

PubMed

Advance directives are designed to establish a person's preferences for treatment if the person becomes incompetent in the future or unable to communicate those preferences to treatment providers. Mental health advance directives are similar to the more commonly used directives for end-of-life medical decisions. A patient must be competent to execute a mental health advance directive, and the directive must clearly express the patient's wishes. Once directives are executed, steps must be taken to ensure compliance, including adequate dissemination to providers, and to ensure that proxy decisions are consistent with the patient's treatment preferences. Potential effects of mental health advance directives include enhanced consumer empowerment; improved functioning; improved communication between consumers, family members, and providers; increased tolerance for consumer autonomy at the organizational level in community mental health agencies; and reduced use of hospital services and judicial proceedings. Issues to be clarified in future research and practice include strategies for increasing awareness of advance directives in mental health, barriers to execution of legally and clinically effective directives, practitioners' concerns, providers' compliance with directives, effects of directives on consumers and providers, effects of managed care on implementation of directives, and stakeholders' perceptions of the value of directives. PMID:10402612

Srebnik, D S; La Fond, J Q

1999-07-01

365

40 CFR 35.116 - Direct implementation.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Direct implementation. 35.116 Section 35.116 Protection of Environment ENVIRONMENTAL PROTECTION...Environmental Program Grants Post-Award Requirements § 35.116 Direct implementation. If funds remain in a...

2010-07-01

366

VOLATILE ORGANIC ANALYSIS BY DIRECT AQUEOUS INJECTION  

EPA Science Inventory

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

367

19 CFR 351.509 - Direct taxes.  

Code of Federal Regulations, 2010 CFR

...ANTIDUMPING AND COUNTERVAILING DUTIES Identification and Measurement of Countervailable Subsidies § 351.509 Direct taxes...a benefit exists to the extent that appropriate interest charges are not collected. Normally, a deferral of direct...

2010-04-01

368

33 CFR 86.07 - Directional properties.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

369

33 CFR 86.07 - Directional properties.  

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

2014-07-01

370

33 CFR 86.07 - Directional properties.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

371

33 CFR 86.07 - Directional properties.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

372

33 CFR 86.07 - Directional properties.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

373

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

374

BIOMEDICAL MATHEMATICS: Promising Directions in Imaging,  

E-print Network

BIOMEDICAL MATHEMATICS: Promising Directions in Imaging, Therapy Planning, and Inverse Problems #12;BIOMEDICAL MATHEMATICS: Promising Directions in Imaging, Therapy Planning, and Inverse Problems Yair Censor, Ming Jiang, Ge Wang Editors The Huangguoshu International Interdisciplinary Conference on Biomedical

Censor, Yair

375

Direct shear testing of polished slickensided surfaces  

Microsoft Academic Search

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

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

2010-01-01

376

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

377

Directional Dark Matter Search and Velocity Distribution  

E-print Network

Directional detection of dark matter is the next generation experiment, which is expected to have better back ground rejection efficiency than conventional direct search. Another intriguing possibility of the experiment by means of the directional information is measurement the velocity distribution of dark matter. Especially, it will be potent to figure out whether the velocity distribution is anisotropic. Supposing three distribution models, we discuss the possibility in one of the directional dark matter searches, nuclear emulsion detector.

Nagao, Keiko I

2014-01-01

378

NASA directives master list and index  

NASA Technical Reports Server (NTRS)

This Handbook sets forth in two parts the information for the guidance of users of the NASA Management Directives System. Complementary to this Handbook is the NASA Online Directives Information System (NODIS), an electronic computer text retrieval system. The first part contains the Master List of Management Directives in force as of 30 Sep. 1993. The second part contains an Index to NASA Management Directives in force as of 30 Sep. 1993.

1993-01-01

379

New directions for veterinary technology.  

PubMed

Veterinary technology has generally established itself well in companion-animal and mixed-animal veterinary medical practice, but the career's growth trajectory is uncertain. Michigan State University (MSU) convened a national conference, "Creating the Future of Veterinary Technology-A National Dialogue," in November 2011 to explore ways to elevate the veterinary technician/technologist's role in the veterinary medical profession and to identify new directions in which the career could expand. Veterinary technicians/technologists might advance their place in private practice by not only improving their clinical skills, but by also focusing on areas such as practice management, leadership training, business training, conflict resolution, information technology, and marketing/communications. Some new employment settings for veterinary technicians/technologists include more participation within laboratory animal medicine and research, the rural farm industry, regulatory medicine, and shelter medicine. Achieving these ends would call for new training options beyond the current 2-year and 4-year degree programs. Participants suggested specialty training programs, hybrid programs of various types, online programs, veterinary technician residency programs of 12-18 months, and more integration of veterinary technician/technology students and veterinary medicine students at colleges of veterinary medicine. PMID:24393780

Chadderdon, Linda M; Lloyd, James W; Pazak, Helene E

2014-01-01

380

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

381

Future Direction of IMIA Standardization  

PubMed Central

Summary Objectives Standardization in the field of health informatics has increased its importance and global alliance for establishing interoperability and compatibility internationally. Standardization has been organized by standard development organizations (SDOs) such as ISO (International Organization for Standardization), CEN (European Committee for Standardization), IHE (Integrating the Healthcare Enterprise), and HL7 (Health Level 7), etc. This paper reports the status of these SDOs’ activities. Methods In this workshop, we reviewed the past activities and the current situation of standardization in health care informatics with the standard development organizations such as ISO, CEN, IHE, and HL7. Then we discussed the future direction of standardization in health informatics toward “future medicine” based on standardized technologies. Results We could share the status of each SDO through exchange of opinions in the workshop. Some WHO members joined our discussion to support this constructive activity. Conclusion At this meeting, the workshop speakers have been appointed as new members of the IMIA working groups of Standards in Health Care Informatics (WG16). We could reach to the conclusion that we collaborate for the international standardization in health informatics toward “future medicine”. PMID:25123729

Kimura, M.; Ogishima, S.; Shabo, A.; Kim, I. K.; Parisot, C.; de Faria Leao, B.

2014-01-01

382

Site-directed ligand discovery  

PubMed Central

We report a strategy (called “tethering”) to discover low molecular weight ligands (?250 Da) that bind weakly to targeted sites on proteins through an intermediary disulfide tether. A native or engineered cysteine in a protein is allowed to react reversibly with a small library of disulfide-containing molecules (?1,200 compounds) at concentrations typically used in drug screening (10 to 200 ?M). The cysteine-captured ligands, which are readily identified by MS, are among the most stable complexes, even though in the absence of the covalent tether the ligands may bind very weakly. This method was applied to generate a potent inhibitor for thymidylate synthase, an essential enzyme in pyrimidine metabolism with therapeutic applications in cancer and infectious diseases. The affinity of the untethered ligand (Ki?1 mM) was improved 3,000-fold by synthesis of a small set of analogs with the aid of crystallographic structures of the tethered complex. Such site-directed ligand discovery allows one to nucleate drug design from a spatially targeted lead fragment. PMID:10944209

Erlanson, Daniel A.; Braisted, Andrew C.; Raphael, Darren R.; Randal, Mike; Stroud, Robert M.; Gordon, Eric M.; Wells, James A.

2000-01-01

383

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

2013-08-01

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.

Kuklo, Thomas C. (Oakland, CA)

1994-01-01

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. 10 figs.

Kuklo, T.C.

1994-10-25

386

Analysis of antidune migration direction  

NASA Astrophysics Data System (ADS)

Antidunes are bed forms characteristic of upper regime unidirectional flows. Contrary to bed forms developed in lower regime flows, antidunes not only can propagate in the downstream direction but can propagate upstream or remain stationary. In this work we analyze the stable hydraulic conditions that determine each of the three antidune movement possibilities, and a new theory is developed for distinguishing the occurrence of each of these conditions. The theory is developed from an energy balance over a symmetrical antidune; for this, the Bernoulli equation is applied between the antidune crest and antidune trough, and the pressure head is corrected to account for the centrifugal forces generated by curvilinear flow. Manipulation of the fundamental equations produces an antidune mobility dimensionless number (Fa), dependent on the Froude number, the mean water depth, and the antidune wavelength. The critical value of the antidune mobility number (Fa = 1) corresponds to the stationary condition, while values higher and lower than the critical correspond to downstream and upstream propagation, respectively. Theory predicts that for a given Froude number, downstream-migrating antidunes are formed for higher water depth-wavelength ratios than for upstream-migrating antidunes. Likewise, by introducing a restriction for the maximum stationary wave height above antidunes, theory predicts that downstream-migrating antidunes could attain steeper height-wavelength ratios than upstream-migrating antidunes. Comparison with published experimental data in literature largely showed agreement between theory and experimental observations.

NúñEz-GonzáLez, Francisco; MartíN-Vide, Juan P.

2011-06-01

387

Direct digital conversion detector technology  

NASA Astrophysics Data System (ADS)

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

Mandl, William J.; Fedors, Richard

1995-06-01

388

Efficiency of parallel direct optimization  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

389

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false Directional antennas. 101.115 Section 101.115 ...Standards § 101.115 Directional antennas. Link to an amendment published at...of this part must employ a directional antenna adjusted with the center of the...

2012-10-01

390

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

391

Relationships between direct predation and risk effects  

Microsoft Academic Search

predation? Second, how are direct effects and risk effects correlated? If riskeffects aresmalland positively relatedto direct effects, then measurements of direct predation rates should provide a good estimate of the total effect of pre- dators on prey. This is the assumption implicit in many studies of predation in natural systems. However, if risk effects are large and negatively related to

Scott Creel; David Christianson

2008-01-01

392

Directional Uncertainty Principle for Quaternion Fourier Transform  

E-print Network

This paper derives a new directional uncertainty principle for quaternion valued functions subject to the quaternion Fourier transformation. This can be generalized to establish directional uncertainty principles in Clifford geometric algebras with quaternion subalgebras. We demonstrate this with the example of a directional spacetime algebra function uncertainty principle related to multivector wave packets.

Eckhard Hitzer

2013-06-06

393

Emerging Perspectives of Self-Directed Learning.  

ERIC Educational Resources Information Center

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

Long, Huey B.; And Others

394

75 FR 12720 - Direct Final Rulemaking Procedures  

Federal Register 2010, 2011, 2012, 2013

...regulations by establishing direct final rulemaking procedures...by the date specified in the direct final rule. These new procedures...rules. FMCSA would not use the direct final rule procedures for complex...regulations.gov. Follow the online instructions for submitting comments....

2010-03-17

395

78 FR 18285 - Direct Final Rulemaking Procedures  

Federal Register 2010, 2011, 2012, 2013

...NHTSA is proposing to establish direct final rulemaking (DFR) procedures...procedures, NHTSA would issue a direct final rule adopting amendments...rules. NHTSA would not use direct final rule procedures for complex...any time. Follow the online instructions for submitting comments....

2013-03-26

396

Air breathing direct methanol fuel cell  

DOEpatents

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

Ren, Xiaoming (Los Alamos, NM)

2002-01-01

397

Racial Threat, Direct Democracy and Social Trust  

Microsoft Academic Search

A number of current empirical studies have demonstrated the virtues of more directly democratic institutional systems in encouraging better democratic citizenship. Both American-based and cross-national studies have found that direct democracy increases turnout, participation, interest group activity, efficacy, knowledge, social capital and even happiness among citizens. In short, direct democracy makes democracies better by helping to encourage better democratic citizenship.

Joshua J. Dyck

2008-01-01

398

Directing cell migration with asymmetric micropatterns  

E-print Network

Directing cell migration with asymmetric micropatterns Xingyu Jiang*, Derek A. Bruzewicz*, Amy P This report shows that the direction of polarization of attached mammalian cells determines the direction constrain individual cells to asymmetric geometries (for example, a teardrop); these geometries polarize

Prentiss, Mara

399

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

400

Computation via Direct Manipulation. Final Report.  

ERIC Educational Resources Information Center

This synthesis of the research on direct manipulation interfaces explores the nature of directness in computer interfaces and demonstrates that the concept of directness is complex, including two gulfs--for execution and evaluation--and two kinds of mappings--semantic mappings and referential distance. Examination of the complexities of the…

Norman, Donald A.; Hutchins, Edwin L., Jr.

401

JORDAN HALL Directions from San Francisco  

E-print Network

JORDAN HALL Directions from San Francisco · Take Highway 101 South. · Exit at Embarcadero Rd, underneath the placard that reads "Jordan Hall". Directions from San Jose · Take Highway 101 North. · Exit at the end of Palm Drive, underneath the placard that reads "Jordan Hall". Directions from Oakland/East Bay

Wagner, Anthony

402

Direct solar energy conversion at sea  

Microsoft Academic Search

Hydrogen production and delivery from direct solar energy conversion facilities located at sea is treated, assuming the use of a heat engine\\/electricity generation\\/water electrolysis system. The concept of ocean energy is discussed, noting the distinction between direct and indirect solar energy conversion at sea, and direct solar energy conversion is considered within the framework of the seaward advancement of industrial

W. J. D. Escher; T. Ohta

1979-01-01

403

Directional emittance corrections for thermal infrared imaging  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

404

Fluctuations along supersymmetric flat directions during Inflation  

E-print Network

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

Kari Enqvist; Daniel G. Figueroa; Gerasimos Rigopoulos

2011-09-14

405

Fluctuations along supersymmetric flat directions during inflation  

SciTech Connect

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

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

2012-01-01

406

Fluctuations along supersymmetric flat directions during Inflation  

E-print Network

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

Enqvist, Kari; Rigopoulos, Gerasimos

2011-01-01

407

Giant components in directed multiplex networks  

NASA Astrophysics Data System (ADS)

We describe the complex global structure of giant components in directed multiplex networks that generalizes the well-known bow-tie structure, generic for ordinary directed networks. By definition, a directed multiplex network contains vertices of one type and directed edges of m different types. In directed multiplex networks, we distinguish a set of different giant components based on the existence of directed paths of different types between their vertices such that for each type of edges, the paths run entirely through only edges of that type. If, in particular, m =2 , we define a strongly viable component as a set of vertices in which for each type of edges each two vertices are interconnected by at least two directed paths in both directions, running through the edges of only this type. We show that in this case, a directed multiplex network contains in total nine different giant components including the strongly viable component. In general, the total number of giant components is 3m. For uncorrelated directed multiplex networks, we obtain exactly the size and the emergence point of the strongly viable component and estimate the sizes of other giant components.

Azimi-Tafreshi, N.; Dorogovtsev, S. N.; Mendes, J. F. F.

2014-11-01

408

Direct manipulation of virtual objects  

NASA Astrophysics Data System (ADS)

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

Nguyen, Long K.

409

Elimination of sex difference in direction giving.  

PubMed

Past studies have shown that men provide more cardinal information and mileage estimates than women when describing routes learned from maps. In the current study, we examined whether this sex difference would persist if more legends were added to the maps. The participants looked at maps for 3 min and then wrote down directions from memory. Their usage of cardinal directions, mileage estimates, landmarks, and left-right directions was coded and analyzed. The results showed that men and women used cardinal directions equally for the 4-legend maps, whereas men used more cardinal directions than women for 1-legend maps as shown previously. Our results suggested that subtly drawing attention to cardinal directions successfully eliminated the sex difference in usage, although a different pattern was seen for mileage estimates. The underlying mechanisms are discussed. PMID:23397104

Wan, Xiaoang; Newcombe, Nora S; Fitzhugh, Shannon

2013-05-01

410

Flow direction determination of lava flows.  

NASA Technical Reports Server (NTRS)

The flow direction technique, previously applied to ash-flow sheets, can be used to determine direction of movement and locate eruptive centers for lava flows. The method provides statistically stronger and more consistent flow direction data for lava than ash-flow tuff. The accuracy and reliability of the technique was established on the porphyritic basaltic andesite of Mount Taylor, New Mexico, which erupted from a known center, the Mount Taylor Amphitheater. The technique was then applied to volcanic units with unknown sources: the John Kerr Peak Quartz Latite and mid-Tertiary andesite flows in the Mogollon Mountains, both in southwestern New Mexico. The flow direction technique indicated flow patterns and suggested source areas for each rock unit. In the Mogollon Mountains flow direction measurements were supported by independent directional criteria such as dips of cross beds, stratigraphic thickening, facies changes, and megascopic textures.-

Smith, E. I.; Rhodes, R. C.

1972-01-01

411

Directional detection of dark matter streams  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

412

Directional emittance surface measurement system and process  

NASA Technical Reports Server (NTRS)

Apparatus and process for measuring the variation of directional emittance of surfaces at various temperatures using a radiometric infrared imaging system. A surface test sample is coated onto a copper target plate provided with selective heating within the desired incremental temperature range to be tested and positioned onto a precision rotator to present selected inclination angles of the sample relative to the fixed positioned and optically aligned infrared imager. A thermal insulator holder maintains the target plate on the precision rotator. A screen display of the temperature obtained by the infrared imager, and inclination readings are provided with computer calculations of directional emittance being performed automatically according to equations provided to convert selected incremental target temperatures and inclination angles to relative target directional emittance values. The directional emittance of flat black lacquer and an epoxy resin measurements obtained are in agreement with the predictions of the electromagnetic theory and with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

Puram, Chith K. (Inventor); Daryabeigi, Kamran (Inventor); Wright, Robert (Inventor); Alderfer, David W. (Inventor)

1994-01-01

413

Directed evolution: selection of the host organism  

PubMed Central

Directed evolution has become a well-established tool for improving proteins and biological systems. A critical aspect of directed evolution is the selection of a suitable host organism for achieving functional expression of the target gene. To date, most directed evolution studies have used either Escherichia coli or Saccharomyces cerevisiae as a host; however, other bacterial and yeast species, as well as mammalian and insect cell lines, have also been successfully used. Recent advances in synthetic biology and genomics have opened the possibility of expanding the use of directed evolution to new host organisms such as microalgae. This review focuses on the different host organisms used in directed evolution and highlights some of the recent directed evolution strategies used in these organisms. PMID:24688653

Pourmir, Azadeh; Johannes, Tyler W.

2012-01-01

414

Flight directions of passerine migrants in daylight and darkness: A radar and direct visual study  

NASA Technical Reports Server (NTRS)

The application of radar and visual techniques to determine the migratory habits of passerine birds during daylight and darkness is discussed. The effects of wind on the direction of migration are examined. Scatter diagrams of daytime and nocturnal migration track directions correlated with wind direction are presented. It is concluded that migratory birds will fly at altitudes where wind direction and migratory direction are nearly the same. The effects of cloud cover and solar obscuration are considered negligible.

Gauthreaux, S. A., Jr.

1972-01-01

415

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

416

Directivity and spacing for the antenna elements  

NASA Technical Reports Server (NTRS)

The optimum design choice for the MST radar antenna was considered. The following factors are required: directivity and gain; beam width and its symmetry; sidelobe levels, near and wide angle; impedance matching; feeder network losses; polarization diversity; steerability; cost effectiveness; and maintainability. The directivity and related beam forming aspects of various antenna elements and directivity aspects when such elements are formed into an array are discussed. Array performance for important variables, in particular, the spacing of the elements is considered.

Koshy, V. K.

1983-01-01

417

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

418

Air breathing direct methanol fuel cell  

DOEpatents

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

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

2002-01-01

419

Direct-Current Injury: Electrochemical Aspects  

Microsoft Academic Search

Direct-current injuries have occurred to anesthetized patients connected to battery-operated medical devices. This study was designed to document the effects of direct current applied to two electrodes on a tissue surrogate (round steak) at room temperature. Direct current from a 9 V source was applied to a pair of stainless steel electrodes (1.6 cm diameter) spaced 4.3 cm center-to-center. Current

L. A. Geddes; R. A. Roeder

2004-01-01

420

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

421

Diffusion tensor images edge-directed interpolation  

Microsoft Academic Search

It has been demonstrated that, for scalar images, edge-directed interpolation techniques are able to produce better results, both visually and quantitatively, than non-adaptive traditional interpolation methods. We have extended the edge-directed concept to the interpolation of multi-valued diffusion tensor images. The interpolation framework is based on the improved edge-directed scalar image interpolation, which does not require estimation of local edges,

Zhenhua Mai; Wolfgang Jacquet; Marleen Verhoye; Jan Sijbers

2010-01-01

422

Direct conversion of algal biomass to biofuel  

DOEpatents

A method and system for providing direct conversion of algal biomass. Optionally, the method and system can be used to directly convert dry algal biomass to biodiesels under microwave irradiation by combining the reaction and combining steps. Alternatively, wet algae can be directly processed and converted to fatty acid methyl esters, which have the major components of biodiesels, by reacting with methanol at predetermined pressure and temperature ranges.

Deng, Shuguang; Patil, Prafulla D; Gude, Veera Gnaneswar

2014-10-14

423

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

424

Experience and Convergence in Spiritual Direction.  

PubMed

The practice of spiritual direction concerns the human experience of God. As praxis, spiritual direction has a long tradition in Western Christianity. It is a process rooted in spirituality with theology as its foundation. This paper explores the convergences between aspects of philosophy (contemplative awareness), psychology (Rogerian client-centered approach) and phenomenology. There are significant points of convergence between phenomenology and spiritual direction: first, in Ignatius of Loyola's phenomenological approach to his religious experience; second, in the appropriation by spiritual directors of concepts of epoch? and empathy; third, in the process of "unpacking" religious experience within a spiritual direction interview. PMID:24469918

Evans, Jean

2014-01-28

425

Self-Organizing Directional Wireless Backbone Networks .  

E-print Network

??Directional wireless communications is emerging as a viable, cost-effective technology for rapidly deployable broadband wireless communication infrastructures. This technology provides extremely high data rates through… (more)

Llorca, Jaime

2008-01-01

426

Master list and index to NASA directives  

NASA Technical Reports Server (NTRS)

All NASA management directives in force as of August 1, 1984 are listed by major subject headings showing number, effective date, title, responsible office, and distribution code. Delegations of authority in print by that date are listed numerically as well as by the installation or office to which special authority is assigned. Other consolidated lists show all management handbooks, directives applicable to the Jet Propulsion Laboratory, directives published in the Code of Federal Regulations, complementary manuals, and NASA safety standards. Distribution policies and instructions for ordering directives are included.

1984-01-01

427

Master list and index to NASA directives  

NASA Technical Reports Server (NTRS)

All NASA management directives in force as of August 1, 1982 are listed by major subject headings showing number, effective data, title, responsible office, and distribution code. Delegations of authority in print by that date are listed numerically as well as by the installation or office to which special authority is assigned. Other consolidated lists show all management handbooks, directives applicable to the Jet Propulsion Laboratory, directions published in the Code of Federal Regulations, complementary manuals, and NASA safety standards. Distribution policies and instructions for ordering directives are included.

1982-01-01

428

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 odd" lang="en"> <div class="resultNumber element">429</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://vwlloyd.mysite.syr.edu/Religion-and-Homosexuality.pdf"> <span id="translatedtitle">RELIGION AND HOMOSEXUALITY <span class="hlt">Directed</span> Reading Course</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">RELIGION AND HOMOSEXUALITY <span class="hlt">Directed</span> Reading Course Georgia State University Fall 2009 Instructor: Vincent Lloyd Preliminary Reading List: Oliver O'Donovan, Church in Crisis (Cascade Books, 2008) George</p> <div class="credits"> <p class="dwt_author">Doyle, Robert</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">430</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950026828&hterms=Narcotics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNarcotics"> <span id="translatedtitle">NASA <span class="hlt">directives</span> master list and index</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This handbook sets forth in two parts, Master List of Management <span class="hlt">Directives</span> and Index to NASA Management <span class="hlt">Directives</span>, the following information for the guidance of users of the NASA Management <span class="hlt">Directives</span> System. Chapter 1 contains introductory information material on how to use this handbook. Chapter 2 is a complete master list of agencywide management <span class="hlt">directives</span>, describing each <span class="hlt">directive</span> by type, number, effective date, expiration date, title, and organization code of the office responsible for the <span class="hlt">directive</span>. Chapter 3 includes a consolidated numerical list of all delegations of authority and a breakdown of such delegation by the office or center to which special authority is assigned. Chapter 4 sets forth a consolidated list of all NASA handbooks (NHB's) and important footnotes covering the control and ordering of such documents. Chapter 5 is a consolidated list of NASA management <span class="hlt">directives</span> applicable to the Jet Propulsion Laboratory. Chapter 6 is a consolidated list of NASA regulations published in the Code of Federal Regulations. Chapter 7 is a consolidated list of NASA regulations published in Title 14 of the Code of Federal Regulations. Complementary manuals to the NASA Management <span class="hlt">Directives</span> System are described in Chapter 8. The second part contains an in depth alphabetical index to all NASA management <span class="hlt">directives</span> other than handbooks, most of which are indexed by titles only.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">431</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://files.eric.ed.gov/fulltext/ED481699.pdf"> <span id="translatedtitle"><span class="hlt">Direct</span> Instruction News: Effective School Practices, 2002.</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">The mission of the Association for <span class="hlt">Direct</span> Instruction is to promote the improvement of effective educational methods. This journal, "<span class="hlt">Direct</span> Instruction News," is their publication. The Spring 2002 issue (Volume 2, Number 1) contains the following articles: "Same? Different? Both Same and Different" (Sara G. Tarver); "Cookie Cutter Curricula" (Bob…</p> <div class="credits"> <p class="dwt_author">Tarver, Sara G., Ed.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">432</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://files.eric.ed.gov/fulltext/ED481700.pdf"> <span id="translatedtitle"><span class="hlt">Direct</span> Instruction News: Effective School Practices, 2003.</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">The mission of the Association for <span class="hlt">Direct</span> Instruction is to promote the improvement of effective educational methods. This journal, "<span class="hlt">Direct</span> Instruction News," is their publication. The Spring 2003 (Volume 3, Number 1) contains the following articles: "Implementing DI Successfully" (Sara G. Tarver); "Textbooks: What?" (Bob Dixon); "Introduction to…</p> <div class="credits"> <p class="dwt_author">Tarver, Sara G., Ed.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">433</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/53267413"> <span id="translatedtitle">Scaling Effects in <span class="hlt">Direct</span> Shear Tests</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">Laboratory experiments of the <span class="hlt">direct</span> shear test were performed on spherical particles of different materials and diameters. Results of the bulk friction vs. non-dimensional shear displacement are presented as a function of the non-dimensional particle diameter. Simulations of the <span class="hlt">direct</span> shear test were performed using the Discrete Element Method (DEM). The simulation results show Considerable differences with the physical experiments.</p> <div class="credits"> <p class="dwt_author">Andrés D. Orlando; Daniel M. Hanes; Hayley H. Shen</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">434</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=susan+baker&id=EJ963164"> <span id="translatedtitle">A Response to "New <span class="hlt">Direction</span> for CCBD?"</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">The author is pleased to see that the future <span class="hlt">directions</span> of the Council for Children with Behavioral Disorders (CCBD) are being addressed. The celebration of the 50th birthday of the inception of CCBD has set the occasion to carefully examine the status quo of the organization and to set future <span class="hlt">directions</span>, as appropriate. The authors of "New…</p> <div class="credits"> <p class="dwt_author">Colvin, Geoff</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">435</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/uw442n5718651l23.pdf"> <span id="translatedtitle"><span class="hlt">Directionally</span> differentiable multiobjective optimization involving discrete inclusions</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">This paper is devoted to multiobjective optimization problems involving discrete inclusions. The objective functions are assumed to be <span class="hlt">directionally</span> differentiable and the domination structure is defined by a closed convex cone. The <span class="hlt">directional</span> derivatives are not assumed to be linear or convex. Several concepts of optimal solutions are analyzed, and the corresponding necessary conditions are obtained as well in maximum</p> <div class="credits"> <p class="dwt_author">Y. Ishizuka; H. D. Tuan</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">436</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/astro-ph/9404053v1"> <span id="translatedtitle"><span class="hlt">Direct</span> mechanism in solar nuclear reactions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">A short overview of the <span class="hlt">direct</span> reaction mechanism and the models used for the analysis of such processes is given. Nuclear reactions proceeding through the <span class="hlt">direct</span> mechanism and involved in solar hydrogen burning are discussed. The significance of these nuclear reactions with respect to the solar neutrino problem is investigated.</p> <div class="credits"> <p class="dwt_author">H. Oberhummer; G. Staudt</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-04-22</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">437</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=form+AND+light&pg=4&id=EJ921305"> <span id="translatedtitle">Spectroscopy and <span class="hlt">Direct</span> Products: Simpler yet Deeper</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">When irreducible representations are given in diagrammatic form, it is possible to show <span class="hlt">direct</span> products pictorially. By giving a similar description of the electric vector associated with a light wave, group-theoretical selection rules (the requirement of a totally symmetric <span class="hlt">direct</span> product) can also be shown in pictorial form. The [upsilon](CO)…</p> <div class="credits"> <p class="dwt_author">Kettle, Sidney F. A.</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">438</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/58740742"> <span id="translatedtitle"><span class="hlt">Direction</span> dependence of the deceleration parameter</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">In this paper we study the possibly existing anisotropy in the accelerating expansion Universe by use of the full sample of Union2 data. Using the hemisphere comparison method to search for a preferred <span class="hlt">direction</span>, we take the deceleration parameter q0 as the diagnostic to quantify the anisotropy level in the wCDM model. We find that the maximum accelerating expansion <span class="hlt">direction</span></p> <div class="credits"> <p class="dwt_author">Rong-Gen Cai; Zhong-Liang Tuo</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">439</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/4785832"> <span id="translatedtitle">Problems concerning global connectivity of <span class="hlt">directed</span> graphs</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 discuss problems and conjectures on global connectivity of <span class="hlt">directed</span> graphs. Lots of information on these and other problems can be found in the forthcoming book [1] which covers connectivity issues of <span class="hlt">directed</span> graphs extensively. In this extended abstract all digraphs are finite and have no loops, but may have parallel arcs. Notation follows [1].</p> <div class="credits"> <p class="dwt_author">Jørgen Bang-jensen</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">440</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=Tor&id=ED526025"> <span id="translatedtitle">On the Strong <span class="hlt">Direct</span> Summand Conjecture</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">In this thesis, our aim is the study the Vanishing of Maps of Tor Conjecture of Hochster and Huneke. We mainly focus on an equivalent characterization called the Strong <span class="hlt">Direct</span> Summand Conjecture, due to N. Ranganathan. Our results are separated into three chapters. In Chapter 3, we prove special cases of the Strong <span class="hlt">Direct</span> Summand Conjecture in…</p> <div class="credits"> <p class="dwt_author">McCullough, Jason</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</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_21");' 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");' 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showDiv("page_24");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" 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">441</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/50361534"> <span id="translatedtitle">GQR models for <span class="hlt">directional</span> wireless channels</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">In this paper, a novel reduced complexity statistical models for the representation of wide sense stationary-uncorrelated scattering <span class="hlt">directional</span> wireless channels affected by Rayleigh fading are developed. Their derivation is based on the so-called Gaussian quadrature rule approach illustrated by E. Chiavaccini and G. M. Vitetta (June 2001) for non <span class="hlt">directional</span> channels. Numerical results evidence, that the proposed models provide a</p> <div class="credits"> <p class="dwt_author">Lodovico Fregni; Fabrizio Muratori; Paola Greco; Giorgio M. Vitetta; Fabrizio Pancaldi</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">442</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/2008PhRvL.101t0502N"> <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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</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">Nikolopoulos, Georgios M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">443</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/37002555"> <span id="translatedtitle">Cease Remembering: Control Processes in <span class="hlt">Directed</span> Forgetting</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">On the premise that committing a word to memory is a type of covert action capable of being stopped, this study merged an item-method <span class="hlt">directed</span> forgetting paradigm with a stop signal paradigm. The primary dependent measure was immediate recall. Indicating that participants were able to countermand the default instruction to remember, there was an overall <span class="hlt">directed</span> forgetting effect, the magnitude</p> <div class="credits"> <p class="dwt_author">Kathleen L. Hourihan; Tracy L. Taylor</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">444</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/1566114"> <span id="translatedtitle"><span class="hlt">Directional</span> scanning of complex electromagnetic environments</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">A <span class="hlt">directional</span> scanning technique is formulated for determining characteristics of an electromagnetic (EM) environment with a relatively small number of measurements, and results of a simulated application are presented. The method relies on measurements with a <span class="hlt">directional</span> probe to obtain information about the coefficients in a planewave expansion of the field within a large volume. The simulation indicates that although</p> <div class="credits"> <p class="dwt_author">J. Randa; M. Kanda</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">445</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/37400229"> <span id="translatedtitle"><span class="hlt">Direct</span> Instruction: a model of instructional design</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">Instructional design is chiefly concerned with the arrangement of the environment to optimise learning according to various criteria. While there are a number of instructional design theories and models, the <span class="hlt">Direct</span> Instruction Model (Engelmann & Carnine, 1982) is the focus of this paper. The importance of instructional design is stressed and the <span class="hlt">Direct</span> Instruction Model is analysed in terms of</p> <div class="credits"> <p class="dwt_author">Joseph Moore</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">446</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=dsc&pg=3&id=ED163704"> <span id="translatedtitle">Replicating <span class="hlt">Direction</span> Service: A Hand Book.</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">The handbook details planning and development of a <span class="hlt">direction</span> service center (DSC), an agency which matches the needs of handicapped persons with appropriate services. A replication sequence, based upon practices of the Jackson County, Missouri, <span class="hlt">Direction</span> Service Center, is discussed for the following six areas: development of a resource…</p> <div class="credits"> <p class="dwt_author">Drake Univ., Des Moines, IA. Midwest Regional Resource Center.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">447</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19690000188&hterms=respiration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drespiration"> <span id="translatedtitle"><span class="hlt">Direct</span> reading of electrocardiograms and respiration rates</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Technique for reading heart and respiration rates is more accurate and <span class="hlt">direct</span> than the previous method. Index of a plastic calibrated card is aligned with a point on the electrocardiogram. Complexes are counted as indicated on the card and heart or respiration rate is read <span class="hlt">directly</span> from the appropriate scale.</p> <div class="credits"> <p class="dwt_author">Wise, J. P.</p> <p class="dwt_publisher"></p> <p class="publishDate">1969-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">448</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19940000111&hterms=emittance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Demittance"> <span id="translatedtitle">Determining <span class="hlt">Directional</span> Emittance With An Infrared Imager</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary"><span class="hlt">Directional</span> emittances of flat specimen of smooth-surfaced, electrically nonconductive material at various temperatures computed from measurements taken by infrared radiometric imager operating in conjunction with simple ancillary equipment. <span class="hlt">Directional</span> emittances useful in extracting detailed variations of surface temperatures from infrared images of curved, complexly shaped other specimens of same material. Advantages: simplification of measurement procedure and reduction of cost.</p> <div class="credits"> <p class="dwt_author">Daryabeigi, Kamran; Alderfer, David W.; Wright, Robert E., Jr.; Puram, Chith K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">449</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/CFR-2013-title19-vol1/pdf/CFR-2013-title19-vol1-sec10-846.pdf"> <span id="translatedtitle">19 CFR 10.846 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p class="result-summary">...an article must be imported <span class="hlt">directly</span> from Haiti into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Haiti to the United States without passing through...intermediate country; (2) If shipment is from Haiti to the United States through the...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">450</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/CFR-2014-title19-vol1/pdf/CFR-2014-title19-vol1-sec10-846.pdf"> <span id="translatedtitle">19 CFR 10.846 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href=""></a></p> <p class="result-summary">...an article must be imported <span class="hlt">directly</span> from Haiti into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Haiti to the United States without passing through...intermediate country; (2) If shipment is from Haiti to the United States through the...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">451</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/CFR-2012-title19-vol1/pdf/CFR-2012-title19-vol1-sec10-846.pdf"> <span id="translatedtitle">19 CFR 10.846 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p class="result-summary">...an article must be imported <span class="hlt">directly</span> from Haiti into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Haiti to the United States without passing through...intermediate country; (2) If shipment is from Haiti to the United States through the...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-01</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.gpo.gov:80/fdsys/pkg/CFR-2010-title19-vol1/pdf/CFR-2010-title19-vol1-sec10-846.pdf"> <span id="translatedtitle">19 CFR 10.846 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p class="result-summary">...an article must be imported <span class="hlt">directly</span> from Haiti into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Haiti to the United States without passing through...intermediate country; (2) If shipment is from Haiti to the United States through the...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2010-04-01</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.gpo.gov:80/fdsys/pkg/CFR-2011-title19-vol1/pdf/CFR-2011-title19-vol1-sec10-846.pdf"> <span id="translatedtitle">19 CFR 10.846 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p class="result-summary">...an article must be imported <span class="hlt">directly</span> from Haiti into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Haiti to the United States without passing through...intermediate country; (2) If shipment is from Haiti to the United States through the...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-04-01</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://ntrs.nasa.gov/search.jsp?R=19870000476&hterms=scanning+acoustic+microscopy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dscanning%2Bacoustic%2Bmicroscopy"> <span id="translatedtitle">Determining <span class="hlt">Directions</span> of Ultrasound in Solids</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Ultrasound shadows cast by grooves. Improved method for determining <span class="hlt">direction</span> of ultrasound in materials is shadow method using Scanning laser acoustic microscopy (SLAM). <span class="hlt">Direction</span> of ultrasound calculated from dimensions of groove and portion of surface groove shields from ultrasound. Method has variety of applications in nontraditional quality-control applications.</p> <div class="credits"> <p class="dwt_author">Generazio, Edward R.; Roth, Don J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</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://eric.ed.gov/?q=Schizophrenia&pg=6&id=EJ839651"> <span id="translatedtitle">Stigma and Schizophrenia: <span class="hlt">Directions</span> in Student Training</span></a>  </p> <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">The persistence of stigma related to schizophrenia is addressed as a continuing challenge for social work students working in mental health. Student education is best grounded in <span class="hlt">direct</span> clinical work with clients in conjunction with field supervision and classroom education. Through <span class="hlt">direct</span> practice in individual and group sessions, students learn…</p> <div class="credits"> <p class="dwt_author">Mason, Susan E.; Miller, Rachel</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</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://www.osti.gov/scitech/biblio/882305"> <span id="translatedtitle">Polar-<span class="hlt">direct</span>-drive simulations and experiments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Polar <span class="hlt">direct</span> drive (PDD) will allow <span class="hlt">direct</span>-drive ignition experiments on the National Ignition Facility (NIF) as it is configured for x-ray drive. Optimal drive uniformity is obtained via a combination of beam repointing, pulse shapes, spot shapes, and/or target design. This article describes progress in the development of standard and "Saturn" PDD target designs.</p> <div class="credits"> <p class="dwt_author">Marozas, J.A.; Marshall, F.J.; Craxton, R.S.; Igumenshchev, I.V.; Skupsky, S.; Bonino, M.J.; Collins, T.J.B.; Epstein, R.; Glebov, V.Yu.; Jacobs-Perkins, D.; Knauer, J.P.; McCrory, R.L.; McKenty, P.W.; Meyerhofer, D.D.; Noyes, S.G.; Radha, P.B.; Sangster, T.C.; Seka, W.; Smalyuk, V.A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-05-17</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.math.tau.ac.il/~krivelev/outbranch.ps"> <span id="translatedtitle">Parameterized Algorithms for <span class="hlt">Directed</span> Maximum Leaf Problems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Parameterized Algorithms for <span class="hlt">Directed</span> Maximum Leaf Problems Noga Alon 1 , Fedor V. Fomin 2 spanning tree, then D contains one with at least (n/2) 1/5 - 1 leaves. 1 Introduction The Maximum Leaf a digraph D, the <span class="hlt">Directed</span> Maximum Leaf Out­Branching problem is the problem of finding an out­branching in D</p> <div class="credits"> <p class="dwt_author">Krivelevich, Michael</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/35071489"> <span id="translatedtitle">Biosensors for <span class="hlt">direct</span> determination of organophosphate pesticides</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>, selective, rapid and simple determination of organophosphate pesticides has been achieved by integrating organophosphorus hydrolase with electrochemical and opitical transducers. Organophosphorus hydrolase catalyzes the hydrolysis of a wide range of organophosphate compounds, releasing an acid and an alcohol that can be detected <span class="hlt">directly</span>. This article reviews development, characterization and applications of organophosphorus hydrolase-based potentiometric, amperometric and optical biosensors.</p> <div class="credits"> <p class="dwt_author">Ashok Mulchandani; Wilfred Chen; Priti Mulchandani; Joseph Wang; Kim R. Rogers</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">459</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.noc.soton.ac.uk/nmf/usl/gxg/UUVS_Science_Directions_talk.pdf"> <span id="translatedtitle">Science <span class="hlt">Directions</span>: AUVs in Ocean Research and</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Science <span class="hlt">Directions</span>: AUVs in Ocean Research and Monitoring Gwyn Griffiths Southampton Oceanography studies Sensors Biomimetic influences #12;Present use: AUVs in Ocean Science Vehicles include: UK rate, releasing algae trapped in the ice. #12;Ocean Monitoring AUV attributes <span class="hlt">Directed</span> track (cf</p> <div class="credits"> <p class="dwt_author">Griffiths, Gwyn</p> <p class="dwt_publisher"></p> <p class="publishDate"></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. Färe</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://www.osti.gov/doepatents/biblio/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">462</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://newcrop.hort.purdue.edu/newcrop/acta694.pdf"> <span id="translatedtitle">Horticultural Plant Breeding: Past Accomplishments, Future <span class="hlt">Directions</span></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">Genetic improvement of agronomic crops through breeding, which typically are marketed as commodities, are grower <span class="hlt">directed</span>. Breeding objectives principally involve increasing yield, often based on resistance to biotic and non-biotic stress. For example improvement in hybrid maize yields have relied on increasing yield stability under high populations. In horticultural crops, breeding objectives must be consumer <span class="hlt">directed</span> because consumers make individual</p> <div class="credits"> <p class="dwt_author">Jules Janick</p> <p class="dwt_publisher"></p> <p class="publishDate"></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.cs.cmu.edu/~anupamg/papers/soda03-dir.pdf"> <span id="translatedtitle">Improved Results for <span class="hlt">Directed</span> Multicut Anupam Gupta</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">for the undirected variant [3]. The first non-trivial approximation algorithm for <span class="hlt">direct</span>- ed multicut, an Ã?´ Ã?Ã?ÐÃ? Ã?µ algorithm gives us the following results. THEOREM 1.1. Given a <span class="hlt">directed</span> multicommodity flow net- work in the following two sections. 2 Relating Cuts and Flows Note that the following integer linear program</p> <div class="credits"> <p class="dwt_author">Gupta, Anupam</p> <p class="dwt_publisher"></p> <p class="publishDate"></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://academic.research.microsoft.com/Publication/58987186"> <span id="translatedtitle">Hospital response to implementation of medical <span class="hlt">directives</span></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">This sandwich thesis presents the findings of a qualitative nested case study that explored the introduction of medical <span class="hlt">directives</span> into clinical practice within a southern Ontario teaching hospital. The purpose of this study was to describe and explore the factors influencing the development and implementation of medical <span class="hlt">directives</span> in the hospital. In-depth, semi-structured interviews were conducted with a purposive sample</p> <div class="credits"> <p class="dwt_author">Kimberley Ann Alvarado</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">465</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://spo.nmfs.noaa.gov/SSRF/SSRF93.pdf"> <span id="translatedtitle"><span class="hlt">DIRECTING</span> THE MOVEMENT OF FISH WITH ELECTRICITY</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary"><span class="hlt">DIRECTING</span> THE MOVEMENT OF FISH WITH ELECTRICITY Marine Biological Laboratory APR 21 1953 WOODS HOLE, Albert M. Day, Director <span class="hlt">DIRECTING</span> THE MOVH-IENT OF FISH WITH ELECTRICITY by Alberton L. McLain Fishery of an electrical leading device 21 Literature cited. ..,...,..,..........·· 2k ILLUSTRATIONS Figure Page 1. Diagram</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></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://ntrs.nasa.gov/search.jsp?R=19950012718&hterms=Narcotics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNarcotics"> <span id="translatedtitle">NASA <span class="hlt">directives</span>: Master list and index</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This Handbook sets forth in two parts the following information for the guidance of users of the NASA Management <span class="hlt">Directives</span> System. Chapter 1 contains introductory information material on how to use this Handbook. Chapter 2 is a complete master list of Agency-wide management <span class="hlt">directives</span>, describing each <span class="hlt">directive</span> by type, number, effective date, expiration date, title, and organization code of the office responsible for the <span class="hlt">directive</span>. Chapter 3 includes a consolidated numerical list of all delegations of authority and a breakdown of such delegation by the office of Installation to which special authority is assigned. Chapter 4 sets forth a consolidated list of all NASA Handbooks (NHB's) and important footnotes covering the control and ordering of such documents. Chapter 5 is a consolidated list of NASA management <span class="hlt">directives</span> applicable to the Jet Propulsion Laboratory. Chapter 6 is a consolidated list of NASA management <span class="hlt">directives</span> published in the code of Federal Regulations. Complementary manuals to the NASA Management <span class="hlt">Directives</span> System are described in Chapter 7. Part B contains an in-depth alphabetical index to all NASA management <span class="hlt">directives</span> other than Handbooks.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</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.gpo.gov:80/fdsys/pkg/CFR-2011-title19-vol1/pdf/CFR-2011-title19-vol1-sec10-711.pdf"> <span id="translatedtitle">19 CFR 10.711 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p class="result-summary">...REDUCED RATE, ETC. United States-Jordan Free Trade Agreement Rules of Origin...a good must be imported <span class="hlt">directly</span> from Jordan into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Jordan to the United States without...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-04-01</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.gpo.gov:80/fdsys/pkg/CFR-2013-title19-vol1/pdf/CFR-2013-title19-vol1-sec10-711.pdf"> <span id="translatedtitle">19 CFR 10.711 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p class="result-summary">...REDUCED RATE, ETC. United States-Jordan Free Trade Agreement Rules of Origin...a good must be imported <span class="hlt">directly</span> from Jordan into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Jordan to the United States without...</p> <div class="credits"> <p class="dwt_author"></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">469</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/CFR-2012-title19-vol1/pdf/CFR-2012-title19-vol1-sec10-711.pdf"> <span id="translatedtitle">19 CFR 10.711 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p class="result-summary">...REDUCED RATE, ETC. United States-Jordan Free Trade Agreement Rules of Origin...a good must be imported <span class="hlt">directly</span> from Jordan into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Jordan to the United States without...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-01</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://www.gpo.gov:80/fdsys/pkg/CFR-2014-title19-vol1/pdf/CFR-2014-title19-vol1-sec10-711.pdf"> <span id="translatedtitle">19 CFR 10.711 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href=""></a></p> <p class="result-summary">...REDUCED RATE, ETC. United States-Jordan Free Trade Agreement Rules of Origin...a good must be imported <span class="hlt">directly</span> from Jordan into the customs territory of the United...mean: (1) <span class="hlt">Direct</span> shipment from Jordan to the United States without...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</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://www.gpo.gov:80/fdsys/pkg/CFR-2010-title19-vol1/pdf/CFR-2010-title19-vol1-sec10-711.pdf"> <span id="translatedtitle">19 CFR 10.711 - Imported <span class="hlt">directly</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p class="result-summary">...REDUCED RATE, ETC. United States-Jordan Free Trade Agreement Rules of Origin...a good must be impor