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1

Carbon aerogel supported Pt–Ru catalysts for using as the anode of direct methanol fuel cells  

Microsoft Academic Search

A carbon aerogel (CA) loaded with platinum nanoparticles can achieve good catalytic performance in proton exchange membrane fuel cells. Pt–Ru bimetallic nanoparticles were loaded onto a carbon aerogel through a simple process. The PtRu\\/CA achieved good cell performance when used as a direct methanol fuel cell anode catalyst. The advantages of carbon aerogel may be attributed to the mesopore structure

Hongda Du; Baohua Li; Feiyu Kang; Ruowen Fu; Yuqun Zeng

2007-01-01

2

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

PubMed

The formation of Pt-Ru nanoclusters (NCs) by sequential deposition of Pt and Ru on a periodically rumpled graphene sheet supported on Ru(0001) is analyzed by atomistic-level modeling and kinetic Monte Carlo simulations. The "coarse-scale" periodic variation of the adsorption energy of metal adatoms across the graphene sheet directs the assembly of NCs to a periodic array of thermodynamically preferred locations. The modeling describes not only just the NC densities and size distributions, but also the composition distribution for mixed NCs. A strong dependence of these quantities on the deposition order is primarily related to different effective mobilities of Pt and Ru on the supported graphene. PMID:23574248

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

2013-04-01

3

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

PubMed

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

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

2012-02-01

4

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

PubMed

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. PMID:24763438

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

2014-05-16

5

Preclinical antitumor activity of a nanoparticulate SN38.  

PubMed

The present studies were carried out to examine the efficacy of a nanoparticulate formulation of SN38, the potent topoisomerase I inhibitor and active metabolite of irinotecan. Metabolism of irinotecan to SN38 is inefficient and subject to considerable patient-to-patient variability. One approach to more controlled administration of the anticancer agent is direct administration of the active SN38. A nanoparticulate formulation of SN38 was prepared by a method of precipitation with compressed antisolvent. Nanoparticulate SN38 efficiently inhibited the proliferation of colorectal, ovarian, and mesothelial cancer cell lines in vitro. Concentrations resulting in 50 % inhibition of proliferation were approximately 1000 fold lower for nanoparticulate SN38 compared to irinotecan. In vivo effects were examined using colorectal and ovarian mouse model systems. In a mouse model of peritoneally disseminated ovarian cancer intraperitoneal administration of irinotecan was favorable to intravenous delivery however intraperitoneal delivery of nanoparticulate SN38 was significantly more effective than intraperitoneal irinotecan. In addition, in a mouse colorectal cancer model administration of nanoparticulate SN38 once weekly exhibited greater activity compared to daily or weekly administration of irinotecan. Additional studies demonstrated nanoparticulate SN38 administered as a combination therapy with mitomycin C was more effective than the combination of irinotecan and mitomycin C. Results from the present studies using preclinical colorectal and ovarian cancer model systems demonstrate the efficacy of nanoparticulate SN38 and substantiate continued development. PMID:23299391

Al-Kasspooles, Mazin F; Williamson, Stephen K; Henry, David; Howell, Jahna; Niu, Fengui; Decedue, Charles J; Roby, Katherine F

2013-08-01

6

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

7

Nanoparticulate systems for polynucleotide delivery  

PubMed Central

Nanotechnology has tremendously influenced gene therapy research in recent years. Nanometer-size systems have been extensively investigated for delivering genes at both local and systemic levels. These systems offer several advantages in terms of tissue penetrability, cellular uptake, systemic circulation, and cell targeting as compared to larger systems. They can protect the polynucleotide from a variety of degradative and destabilizing factors and enhance delivery efficiency to the cells. A variety of polymeric and non-polymeric nanoparticles have been investigated in an effort to maximize the delivery efficiency while minimizing the toxic effects. This article provides a review on the most commonly used nanoparticulate systems for gene delivery. We have discussed frequently used polymers, such as, polyethyleneimine, poly (lactide-co-glycolide), chitosan, as well as non-polymeric materials such as cationic lipids and metallic nanoparticles. The advantages and limitations of each system have been elaborated. PMID:18019834

Basarkar, Ashwin; Singh, Jagdish

2007-01-01

8

Nanoparticulate delivery systems for antiviral drugs.  

PubMed

Nanomedicine opens new therapeutic avenues for attacking viral diseases and for improving treatment success rates. Nanoparticulate-based systems might change the release kinetics of antivirals, increase their bioavailability, improve their efficacy, restrict adverse drug side effects and reduce treatment costs. Moreover, they could permit the delivery of antiviral drugs to specific target sites and viral reservoirs in the body. These features are particularly relevant in viral diseases where high drug doses are needed, drugs are expensive and the success of a therapy is associated with a patient's adherence to the administration protocol. This review presents the current status in the emerging area of nanoparticulate delivery systems in antiviral therapy, providing their definition and description, and highlighting some peculiar features. The paper closes with a discussion on the future challenges that must be addressed before the potential of nanotechnology can be translated into safe and effective antiviral formulations for clinical use. PMID:21107015

Lembo, David; Cavalli, Roberta

2010-01-01

9

Solution processable interface materials for nanoparticulate organic photovoltaic devices  

NASA Astrophysics Data System (ADS)

Nanoparticulate zinc oxide can be prepared at low temperatures from solution processable zinc acetylacetonate. The use of this material as a cathode interfacial layer in nanoparticulate organic photovoltaic devices results in comparable performances to those based on reactive calcium layers. Importantly, the enhanced degradation stability and full solution processability make zinc oxide a more desirable material for the fabrication of large area printed devices.

Nicolaidis, Nicolas; Vaughan, Ben; Mulligan, Cara J.; Bryant, Glenn; Zillger, Tino; Trnovec, Bystrik; Hübler, Arved C.; Holmes, Natalie; Cooling, Nathan A.; Griffith, Matthew J.; Bilen, Chhinder; Kumar, Pankaj; Feron, Krishna; Zhou, Xiaojing; Elkington, Daniel; Belcher, Warwick J.; Dastoor, Paul C.

2014-01-01

10

LBPS/CSPBAT Les nanoparticules hybrides rsultent d'un  

E-print Network

objectif, en développant des méthodes de synthèse de nanoparticules à base d'oxyde de fer, de nanoparticules d'oxyde de fer associés à la fonctionnalisation de surface par des molécules spécifiques permet d

Powell, Geoffrey

11

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

12

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

NASA Astrophysics Data System (ADS)

Nitrogen-doped mesoporous carbons (NMPCs) with well-developed polyhedral morphology were prepared by direct carbonization of zeolitic imidazolate framework-8 (ZIF-8) nanopolyhedrons. The fantastic structural characteristics of NMPCs such as ultrahigh BET surface area (1960 m2 g-1), large pore volume (1.16 cm3 g-1), and nitrogen doping make it an excellent catalyst support. PtRu nanoparticles (with a size of approximately 1.9 nm) were homogeneously supported on NMPCs by microwave-assisted reduction in ethylene glycol, and the obtained PtRu/NMPCs catalyst shows a significantly higher electrocatalytic activity and stability for methanol oxidation than the typical commercial PtRu/C (E-TEK) catalyst.

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

2014-04-01

13

Berberine hydrochloride: anticancer activity and nanoparticulate delivery system  

PubMed Central

Background Berberine hydrochloride is a conventional component in Chinese medicine, and is characterized by a diversity of pharmacological effects. However, due to its hydrophobic properties, along with poor stability and bioavailability, the application of berberine hydrochloride was hampered for a long time. In recent years, the pharmaceutical preparation of berberine hydrochloride has improved to achieve good prospects for clinical application, especially for novel nanoparticulate delivery systems. Moreover, anticancer activity and novel mechanisms have been explored, the chance of regulating glucose and lipid metabolism in cancer cells showing more potential than ever. Therefore, it is expected that appropriate pharmaceutical procedures could be applied to the enormous potential for anticancer efficacy, to give some new insights into anticancer drug preparation in Chinese medicine. Methods and results We accessed conventional databases, such as PubMed, Scope, and Web of Science, using “berberine hydrochloride”, “anti-cancer mechanism”, and “nanoparticulate delivery system” as search words, then summarized the progress in research, illustrating the need to explore reprogramming of cancer cell metabolism using nanoparticulate drug delivery systems. Conclusion With increasing research on regulation of cancer cell metabolism by berberine hydrochloride and troubleshooting of issues concerning nanoparticulate delivery preparation, berberine hydrochloride is likely to become a natural component of the nanoparticulate delivery systems used for cancer therapy. Meanwhile, the known mechanisms of berberine hydrochloride, such as decreased multidrug resistance and enhanced sensitivity of chemotherapeutic drugs, along with improvement in patient quality of life, could also provide new insights into cancer cell metabolism and nanoparticulate delivery preparation. PMID:21931477

Tan, Wen; Li, Yingbo; Chen, Meiwan; Wang, Yitao

2011-01-01

14

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

E-print Network

*, Department of Chemistry and School of Molecular Science (BK 21), Korea AdVanced Institute of Science calls for careful studies on size- and shape-related catalyst performance excluding the effect, stoichiometrically uniform PtRu nanoparticles to improve the catalyst performance. In this paper, we report a simple

Kwak, Juhyoun

15

Particle size effects of PtRu nanoparticles embedded in TiO 2 on methanol electrooxidation  

Microsoft Academic Search

Size-controlled PtRu nanoparticles embedded in TiO2 were prepared by simultaneous multi-gun sputtering from pure targets of Pt, Ru, and TiO2. The mean diameter of the PtRu nanoparticles, as confirmed by their high-resolution transmission electron microscopic images, can be varied from ?1.8 to ?3.7nm by changing the RF power ratio of PtRu and TiO2. The transmission electron diffraction and grazing incidence

Sung Jong Yoo; Tae-Yeol Jeon; Yong-Hun Cho; Kug-Seung Lee; Yung-Eun Sung

2010-01-01

16

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

NASA Astrophysics Data System (ADS)

The influence of PtRu surface alloy formation and of coadsorbed CO on the adsorption/desorption characteristics of hydrogen on bimetallic PtRu surfaces was investigated by temperature programmed desorption, using a 40% Pt containing PtRu surface alloy pseudomorphic on a Ru(0 0 0 1) surface with an almost statistical distribution of Pt surface atoms as substrate. Alloy formation leads to a significant broadening of the desorption peak compared to pure Ru, together with a considerable down-shift in the onset of desorption. This trend is even more pronounced in the presence of coadsorbed CO. The weakening of the hydrogen adsorption bond is attributed mainly to strain effects, imposed by the considerable compression of the pseudomorphic Pt as compared to bulk Pt(1 1 1). Finally we discuss the implications of these results for the mechanistic understanding of the improved performance of PtRu anode catalysts in reformate operated polymer electrolyte fuel cells.

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

2003-09-01

17

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

Microsoft Academic Search

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

Joyeeta Bagchi; Swapan Kumar Bhattacharya

2007-01-01

18

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

19

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

20

First-principles study of the role of solvent in the dissociation of water over a Pt-Ru alloy  

NASA Astrophysics Data System (ADS)

Self-consistent gradient-corrected periodic density functional theoretical calculations are used to examine the effects of an aqueous environment on the dissociation of water over a Pt-Ru alloy. This reaction is thought to be one of the rate-limiting steps in oxidative removal of CO from the anode surface of both the direct methanol and reformate fuel cells. The reaction leads to the formation of surface hydroxyl (OH) intermediates that can subsequently oxidize adsorbed CO into CO2. We examine the energetics and mechanism for the dissociation of water over Pt66Ru33(111) in the presence of 23 water molecules (per 615 Å3 unit cell volume) that act as a solution phase and in the absence of solution (vapor phase). The reaction is endothermic by +53 kJ/mol and has an activation barrier of +105 kJ/mol when carried out in the vapor phase, but was found to be much less endothermic (+26 kJ/mol) and has a significantly lower activation barrier (+27 kJ/mol) when carried out in solution. In the vapor phase, the reaction occurs homolytically whereby the dissociation is activated by insertion of a Ru atom into the O-H bond of water. The products formed are adsorbed hydroxyl and hydrogen intermediates. In contrast, in solution, the dissociation occurs via a heterolytic path whereby the solvent molecules are directly involved in activating the O-H bond. The reaction leads to the formation of a hydroxyl intermediate that is bound to the alloy surface and a proton that is released into the solution phase. Ab initio molecular dynamics simulations were performed at 300 K to establish the sequence of elementary steps that can occur. The simulations show that water dissociates over Ru and that the hydroxyl intermediate that first forms over Ru rapidly diffuses along the metal surface, migrating over Pt as well as Ru sites. We believe that this evidence shows that diffusion occurs as the result of the proton transfer between the coadsorbed water and hydroxyl intermediates in an aqueous environment. This could have important consequences for CO oxidation in PEM fuel cells whereby the diffusion of CO and/or OH intermediates is important for the reaction at the edge of the Pt/Ru boundaries. The work reported herein applies at open-circuit potentials, but may also be appropriate at other potentials as well.

Desai, Sanket K.; Neurock, Matthew

2003-08-01

21

Glycerol Hydrogenolysis on Carbon-Supported PtRu and AuRu Bimetallic Catalysts  

SciTech Connect

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

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

2007-01-01

22

Online analysis of carbon dioxide from a direct ethanol fuel cell  

Microsoft Academic Search

Carbon dioxide yields from a direct ethanol fuel cell have been monitored by using a commercial infrared CO2 monitor. The time dependence is reported as a function of temperature, current density, and anode catalyst (Pt vs. PtRu). Yields increased strongly with temperature, with a Faradaic yield of 76% being obtained at 100°C with a Pt black anode. PtRu gave lower

Azra Ghumman; Guangchun Li; Dwayne V. Bennett; Peter G. Pickup

2009-01-01

23

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.

24

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

25

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

PubMed

The ferritin core is composed of fine nanoparticulate Fe(3+) oxohydroxide, and we have developed a synthetic mimetic, nanoparticulate Fe(3+) polyoxohydroxide (nanoFe(3+)). 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 Fe(2+) sulfate (FeSO4), nanoFe(3+), or no added Fe for a further 4 wk. A control group was Fe sufficient throughout. Direct intestinal absorption of nanoFe(3+) was investigated using isolated duodenal loops. Our data show that FeSO4 and nanoFe(3+) 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 nanoFe(3+) group. Oral iron failed to be utilized by Fpn-KO mice and was retained in enterocytes, irrespective of the iron source. In summary, although nanoFe(3+) 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. 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

2014-08-01

26

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

27

In vitro and in vivo equivalence testing of nanoparticulate intravenous formulations.  

PubMed

The topic of bioequivalence evaluation of nanoparticulate intravenous formulations is one that has been intensely debated in recent times since the release of the specific recommendations by many regulatory authorities worldwide. Product specific bioequivalence guidelines for many of the nanoparticulate systems where therapeutic molecules are directly coupled (human albumin bound paclitaxel nanosuspension), functionalized (iron- carbohydrate preparations) or entrapped/coated to a carrier (doxorubicin liposomal formulations), have been approved by the drug regulatory agencies. These current regulatory procedures include complete characterization of the generic formulation in terms of its physicochemical characteristics, pharmacokinetics disposition and/or non clinical testing with respect to the reference formulation. The concept of in vitro equivalency is emerging as a valuable tool in these guidances as generic product differing in in vitro parameters can result in a different biopharmaceutical profile with respect to pharmacokinetics and biodistribution. Furthermore, in case of systems with entrapped drug, classical pharmacokinetic parameters alone may only ensure the equivalent clearance of test and reference product from systemic circulation but may fail to detect the extent to which the nanoparticles are taken up by different target organs and, consequently, the safety and efficacy effects. Hence, additional tissue distribution study in preclinical study models has reflected in recent guidances. Understanding and interpretation of these regulatory requirements thus presents most critical component of a generic product development cycle. This article reviews these current regulatory procedures with special emphasis on in vitro population bioequivalence (POP BE) and preclinical testing of generic formulations. PMID:24203084

Pathak, S M; Ruby, P K; Aggarwal, D

2014-04-01

28

Advances in direct oxidation methanol fuel cells  

Microsoft Academic Search

FLICI cells that can operate directly on fuels such as methanol are attractive for low to medium power appl i cations in view of their low weight. and volume relative to other power sources. A liquid feed direct methanol fuel cell has been developed based on a proton exchange membrane electrolyte and Pt\\/Ru and Pt catalyzed fuel and air\\/02 electrodes

G. K. Suryaprakash; G. A. Olah; E. Vamos; H. Frank; G. Halpert; A. LaConti; J. Kosek; G. K. Surya Prakash

1994-01-01

29

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

30

Development of a polymeric nanoparticulate delivery system for indocyanine green  

NASA Astrophysics Data System (ADS)

Purpose. The objective of this project was to develop an intravenously administrable poly(dl-lactic-co-glycolic acid) (PLGA) nanoparticulate delivery system for Indocyanine Green (ICG), to enhance the potential for ICG use in tumor imaging and therapy. Methods. For this purpose PLGA nanoparticles entrapping ICG were engineered by spontaneous emulsification solvent diffusion method. ICG entrapment in nanoparticles was determined and physicochemical characterization of nanoparticles was performed. The stability of ICG in nanoparticles formulation under various conditions was determined. The intracellular uptake of ICG in nanoparticles by B16-F10 and C-33A cancer cell lines was studied in comparison with the free ICG solution. Anti-proliferation studies against cancer cells were performed to prove the photodynamic activity of ICG in nanoparticles. Biodistribution of ICG when delivered through nanoparticles and solution were evaluated in mice after tail vein injection. Results. PLGA nanoparticles with a mean diameter of 350 nm and 74% ICG entrapment were obtained. The nanoparticles were nearly spherical in shape with zeta potential of -16 mV. The nanoparticles formulation provided overall stability to ICG with degradation half-lives of 2.5--3.5 days as compared to 10--20 hr of free ICG solutions. The intracellular uptake of ICG through nanoparticles was directly proportional to time and extracellular nanoparticle concentration. The intracellular uptake of ICG was enhanced about 100-fold by nanoparticles formulation as compared to the free ICG solution. Nanoparticles formulation showed significant photodynamic effect at nano-molar ICG concentrations and very low light dose (fluence: 0.22 W/cm2 and energy density: 1.1 J/cm2). In-vivo, the blood circulation-time and retention-time of ICG in various organs was enhanced 2--5 times by nanoparticles formulation as compared to the free ICG solution. Conclusions. A PLGA nanoparticlute delivery system was developed for ICG, which demonstrated its capability in enhancing the potential of ICG use in tumor diagnosis and anticancer therapy.

Saxena, Vishal

31

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

32

Significant Role of Ru-Oxide Present in the Pt-Ru Alloy Catalyst for Ethanol ElectroOxidation in Acid Medium  

Microsoft Academic Search

This work relates to the search for optimum Pt-Ru catalyst composition for electro-oxidation of ethanol. The structure, morphology, and composition of the synthesized Pt-Ru catalysts were investigated through techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) while cyclic-voltammetry, polarization, chronoamperometry, impedance spectroscopy were employed to study the electrocatalytic behavior of

J. Datta; S. Sen Gupta; S. Singh; S. Mukherjee; M. Mukherjee

2011-01-01

33

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

E-print Network

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

Mu, L.

34

The synthesis of metal nanoparticulate catalysts within functional microgel particles  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

35

Multifunctional, stimuli-sensitive nanoparticulate systems for drug delivery.  

PubMed

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

Torchilin, Vladimir P

2014-11-01

36

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

NASA Astrophysics Data System (ADS)

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

Hebert, Etienne M.

37

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

38

X-ray absorption and electrochemical studies of direct methanol fuel cell catalysts  

SciTech Connect

In order for polymer electrolyte fuel cells to operate directly on methanol instead of hydrogen, methanol oxidation must be catalyzed in the acidic cell environment. Pt-Ru and Pt-Ru oxide are considered to be the most active catalysts for this purpose; Ru enhances the Pt activity for reasons not yet fully understood. XAS and electrochemical techniques were used to study this enhancement. Preliminary results indicate that Ru does effect the d-band occupancy of Pt, which in turn may effect the kinetics of the methanol oxidation reaction on this metal by altering the strength of the Pt-CO bond. Further research is needed.

Zurawski, D.J.; Aldykiewicz, A.J. Jr.; Baxter, S.F.; Krumpelt, M.

1996-12-31

39

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

NASA Astrophysics Data System (ADS)

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

Hatton, Bryan; Rickard, David

2008-06-01

40

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

41

Multistrain influenza protection induced by a nanoparticulate mucosal immunotherapeutic.  

PubMed

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 to elicit potent innate and selective T cell-based adaptive immune responses. Prepared without virus-specific peptides, mucosal immunostimulatory therapeutic (MIT) provided robust, but short-lived, protection against multiple, highly lethal strains of influenza in mice of diverse genetic backgrounds. MIT prepared with three highly conserved epitopes that elicited virus-specific memory T-cell responses but not neutralizing antibodies, termed MITpep, provided equivalent, but more durable, protection relative to MIT. Alveolar macrophages were more important than dendritic cells in determining the protective efficacy of MIT, which induced both canonical and non-canonical antiviral immune pathways. Through activation of airway mucosal innate and highly specific T-cell responses, MIT and MITpep represent novel approaches to antiviral protection that offer the possibility of universal protection against epidemic and pandemic influenza. PMID:20736998

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

2011-03-01

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

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

PubMed Central

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

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

2013-01-01

44

Cellular Partitioning of Nanoparticulate versus Dissolved Metals in Marine Phytoplankton.  

PubMed

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

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

2014-11-18

45

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

46

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

47

Design issues for improved environmental performance of dye-sensitized and organic nanoparticulate solar cells  

Microsoft Academic Search

Though environmental improvement has been claimed for the application of nanotechnology to solar cells, several characteristics of the fullerene-based organic, and the dye-sensitized nanoparticulate, solar cell are not conducive to such improvement. These include relatively high energy and materials inputs in the production of nanoparticles, a relatively low solar radiation to electricity conversion efficiency, a relatively short service life, the

L. Reijnders

2010-01-01

48

Diode behavior of electrophoretically deposited polyaniline on TiO2 nanoparticulate thin film electrode.  

PubMed

An inorganic/organic hetrostructure diode was constructed by the electrophoretic deposition of the p-type polyaniline (PANI) on an n-type titanium oxide (TiO2) nanoparticulate thin film. The bonding and internalization of PANI to TiO2 nanoparticulate thin film were confirmed by the morphological, structural and optical studies of electrophoretically deposited PANI/TIO2 nanoparticulate thin film. The increased size of TiO2 nanoparticles indicated the well penetration of PANI molecules into the pores of mesoporous TiO2 nanoparticulate thin film. The XPS studies of PANI/TiO2 heterostructure exhibited the surface bonding and interaction between PANI molecules and TiO2 nanoparticles. The current-voltage (I-V) characterization of PANI/TiO2 heterostructure was carried out in the forward and the reverse bias at the applied voltage ranges from -1 V to +1 V with a scan rate of 2 mV/s. The constructed Pt/PANI/TiO2 heterostructure device established diodic behavior with non-linear nature of I-V curves. PMID:21456236

Ameen, Sadia; Akhtar, M Shaheer; Kim, Young Soon; Yang, O-Bong; Shin, Hyung-Shik

2011-02-01

49

XAFS Analysis of Pt and Pt-Ru Catalysts for PEFCs by In-Situ Measurements under Operating Conditions in the Fluorescence Mode  

SciTech Connect

In-situ X-ray absorption fine structure (XAFS) is one of powerful spectroscopic techniques to analyze valence state and chemical bonding in Pt and Pt-Ru electrocatalysts under fuel cell operating conditions. We measured Pt L3 and Ru K-XAFS of Pt and Pt-Ru electrocatalysts in fluorescence mode under different operation voltages using pure H2 or 97 ppm CO containing H2 as fuel gases that were fed to the anode. The radial structure functions that derived from the obtained XAFS spectra showed that the local structure around Pt and Ru atoms in the electrocatalysts changes depending on the operation voltage and shows difference with the existence of CO in the fuel gas.

Kageyama, Hiroyuki; Ioroi, Tsutomu; Kojima, Toshikatsu; Senoh, Hiroshi; Takeichi, Nobuhiko; Nomura, Katsuhiro; Tanimoto, Kazumi [National Institute of Advanced Industrial Science and Technology (AIST), Research Institute for Ubiquitous Energy Devices, Midorigaoka 1-8-31, Ikeda, Osaka 563-8577 (Japan)

2007-02-02

50

Direct ethanol fuel cells using an anion exchange membrane  

Microsoft Academic Search

Direct ethanol fuel cells (DEFCs) with a PtRu anode and a Pt cathode were prepared using an anion exchange membrane (AEM) as an electrolyte instead of a cation exchange membrane (CEM), as in conventional polymer electrolyte fuel cells. The maximum power density of DEFCs significantly increased from 6mWcm?2 to 58mWcm?2 at room temperature and atmospheric pressure when the electrolyte membrane

Naoko Fujiwara; Zyun Siroma; Shin-ichi Yamazaki; Tsutomu Ioroi; Hiroshi Senoh; Kazuaki Yasuda

2008-01-01

51

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

SciTech Connect

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

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

1997-04-01

52

Ultrahigh methanol electro-oxidation activity of PtRu nanoparticles prepared on TiO2-embedded carbon nanofiber support  

NASA Astrophysics Data System (ADS)

A TiO2-embedded carbon nanofiber (TECNF) was proposed as a promising support of the PtRu nanocatalyst for the methanol oxidation reaction. The nanofiber support was prepared by the electrospinning of polyacrylonitrile (PAN) with TiO2 nanoparticles followed by carbonization and steam activation of the nanofiber, and lastly, the PtRu nanoparticles deposition. Cyclic voltammetry (CV) revealed a significantly high MOR activity for the PtRu/TECNF compared to that of the PtRu nanoparticles deposited on different supports, i.e., carbon black (C), TiO2 nanoparticles (TiO2), a mixture of these nanoparticles (C + TiO2) and carbon nanofiber (CNF). The MOR activity was high in the order of PtRu/TECNF > PtRu/CNF > PtRu/(C + TiO2) > PtRu/C >> PtRu/TiO2. The activity of PtRu/TECNF increased with an increase in the weight ratio of Ti/C for TECNF up to 1.0 and then decreased. The MOR mass activity of PtRu/TECNF at the optimum Ti/C ratio was 4 times higher than that of PtRu/C. The ultrahigh catalytic activity of PtRu/TECNF is attributed to the metal-support interaction, which efficiently occurs at the PtRu/TECNF structure. The ultrahigh catalytic activity was also confirmed by the two-times higher DMFC power output using PtRu/TECNF, in spite of quarter the PtRu loading on the electrode, compared to that using the commercial PtRu/C.

Ito, Yudai; Takeuchi, Taizo; Tsujiguchi, Takuya; Abdelkareem, Mohammad Ali; Nakagawa, Nobuyoshi

2013-11-01

53

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

Microsoft Academic Search

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

Vaithilingam Selvaraj; Muthukaruppan Alagar

2008-01-01

54

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

55

Structure and electrochemical activity of WOx-supported PtRu catalyst using three-dimensionally ordered macroporous WO3 as the template  

NASA Astrophysics Data System (ADS)

PtRu/WOx catalyst is prepared in a polyol process with three-dimensionally ordered macroporous (3DOM) WO3 as the template in combination with an ammonia-leaching treatment. The morphology, composition and structure of the prepared catalysts are characterized by scanning transmission electron microscopy, energy dispersion X-ray spectroscopy, N2 adsorption, X-ray photoelectron spectroscopy and X-ray diffraction. The electrochemical activities are evaluated by linear sweep voltammetry, cyclic voltammetry, and chronoamperometry measurements in combination with in situ IR reflection absorption spectroscopy (IRRAS). The composition and particle size of the PtRu/WOx catalyst are similar to those of the PtRu catalyst prepared without the 3DOM WOx template, and both of the catalysts have a uniform element distribution, however, the PtRu/WOx catalyst has a more porous structure and greater metallic Pt proportion due to the support role of the residual WOx template and the interaction between WOx and PtRu nanoparticles. Electrochemical and in situ IRRAS measurements indicate that the PtRu/WOx catalyst has a greater electro-catalytic activity for methanol oxidation than the PtRu catalyst due to the assisting catalytic role of WOx and mass transport benefit of the porous structure.

Wang, Qi; Wang, Guoxiong; Sasaki, Keisuke; Takeguchi, Tatsuya; Yamanaka, Toshiro; Sadakane, Masahiro; Ueda, Wataru

2013-11-01

56

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

Cancer.gov

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

57

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

Microsoft Academic Search

With the scientific progress in cancer biology, pharmacology and biomedical engineering, the nano-biotechnology based imaging probes and therapeutical agents (namely probes\\/agents) - a form of theranostics - are among the strategic solutions bearing the hope for the cure of cancer. The key feature distinguishing the nanoparticulated probes\\/agents from their conventional counterparts is their targeting capability. A large surface-to-volume ratio in

Xiangyang Tang; Yi Yang; Shaojie Tang

2011-01-01

58

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

59

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

60

High performance direct ethanol fuel cell with double-layered anode catalyst layer  

Microsoft Academic Search

Double-layered anode catalyst layers with two reverse configurations, which consist of 45wt.% Pt3Sn\\/C and PtRu black catalyst layers, were fabricated to improve the performance of a direct ethanol fuel cell (DEFC). The in-house 45wt.% Pt3Sn\\/C catalyst was characterized by XRD and TEM. The cross-sectional double-layered anode catalyst layer was observed by SEM. In DEFC performance test and anode linear sweep

Q. Wang; G. Q. Sun; L. Cao; L. H. Jiang; G. X. Wang; S. L. Wang; S. H. Yang; Q. Xin

2008-01-01

61

Fabrication of an inkjet-printed seed pattern with silver nanoparticulate ink on a textured silicon solar cell wafer  

NASA Astrophysics Data System (ADS)

In this study, the possibility of using inkjet printing in the fabrication of a conductive seed pattern on a textured silicon solar wafer is investigated. Firstly, solar cell wafers were coated with a hydrophobic solution. It was found that the surface texture of a solar cell wafer causes a slight increase in the contact angle of silver nanoparticulate ink by 7.5° due to a weak Cassie-Baxter wetting state. After selective laser ablation of the hydrophobic coating and the SiNx layer in preparation for the surface energy-patterned finger electrode regions, silver nanoparticulate ink was deposited with a piezo drop-on-demand inkjet print head. Because the threshold laser fluence for the ablation of the hydrophobic coating is lower than that for the SiNx layer, the effective width of a surface energy-patterned finger electrode region with the Gaussian laser beam profile was found to be wider than the actual width of the SiNx-ablated region. Although this initially results in a widened deposition of silver nanoparticulate ink, the subsequent drying of silver nanoparticulate ink is found to cause a reduction of line width of around 6% to 14%. Therefore, the final line width of the seed pattern is the outcome of two opposing phenomena. The physical and electrical characteristics of the seed pattern are as narrow as 58.5 ± 1.2 µm, as thick as 1.81 µm on average and as conductive as 2.72 µ? cm.

Shin, Dong-Youn

2010-12-01

62

Ethylene glycol oxidation on Pt and Pt-Ru nanoparticle decorated polythiophene/multiwalled carbon nanotube composites for fuel cell applications.  

PubMed

A novel supporting material containing polythiophene (PTh) and multiwalled carbon nanotubes (MWCNTs) (PTh-CNTs) is prepared by in situ polymerization of thiophene on carbon nanotubes using FeCl(3) as oxidizing agent under sonication. The prepared polythiophene/CNT composites are further decorated with Pt and Pt-Ru nanoparticles by chemical reduction of the corresponding metal salts using HCHO as reducing agent at pH = 11 (Pt/PTh-CNT and Pt-Ru/PTh-CNT). The fabricated composite films decorated with nanoparticles were investigated towards the electrochemical oxidation of ethylene glycol (EG). The presence of carbon nanotubes in conjugation with a conducting polymer produces a good catalytic effect, which might be due to the higher electrochemically accessible surface areas, electronic conductivity and easier charge-transfer at polymer/electrolyte interfaces, which allows higher dispersion of Pt and Pt-Ru nanoparticles. Such nanoparticle modified PTh-CNT electrodes exhibit better catalytic behavior towards ethylene glycol oxidation. Results show that Pt/PTh-CNT and Pt-Ru/PTh-CNT modified electrodes show enhanced electrocatalytic activity and stability towards the electro-oxidation of ethylene glycol than the Pt/PTh electrodes, which shows that the composite film is more promising for applications in fuel cells. PMID:21817505

Selvaraj, Vaithilingam; Alagar, Muthukaruppan

2008-01-30

63

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

NASA Astrophysics Data System (ADS)

A novel supporting material containing polythiophene (PTh) and multiwalled carbon nanotubes (MWCNTs) (PTh-CNTs) is prepared by in situ polymerization of thiophene on carbon nanotubes using FeCl3 as oxidizing agent under sonication. The prepared polythiophene/CNT composites are further decorated with Pt and Pt-Ru nanoparticles by chemical reduction of the corresponding metal salts using HCHO as reducing agent at pH = 11 (Pt/PTh-CNT and Pt-Ru/PTh-CNT). The fabricated composite films decorated with nanoparticles were investigated towards the electrochemical oxidation of ethylene glycol (EG). The presence of carbon nanotubes in conjugation with a conducting polymer produces a good catalytic effect, which might be due to the higher electrochemically accessible surface areas, electronic conductivity and easier charge-transfer at polymer/electrolyte interfaces, which allows higher dispersion of Pt and Pt-Ru nanoparticles. Such nanoparticle modified PTh-CNT electrodes exhibit better catalytic behavior towards ethylene glycol oxidation. Results show that Pt/PTh-CNT and Pt-Ru/PTh-CNT modified electrodes show enhanced electrocatalytic activity and stability towards the electro-oxidation of ethylene glycol than the Pt/PTh electrodes, which shows that the composite film is more promising for applications in fuel cells.

Selvaraj, Vaithilingam; Alagar, Muthukaruppan

2008-01-01

64

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

PubMed

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

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

2007-11-01

65

Effect of Si3N4 nanoparticulates on the mechanical and electrical properties of PZT ceramics  

NASA Astrophysics Data System (ADS)

PZT/xSi3N4 ceramics (when x=0, 0.1, 0.5 and 1 wt.%) were prepared by a solid-state mixed-oxide method and sintered at 1125 °C for 2 h. X-ray diffraction results suggested that the addition of Si3N4 nanoparticulates did not significantly affect the unit cell and tetragonality of PZT. The addition of 0.1 wt.% Si3N4 effectively increased the density and reduced the grain size of PZT ceramics. These changes played an important role in hardness and fracture toughness improvement. The maximum room temperature dielectric constant was achieved in a PZT/0.1 wt.% Si3N4 sample. Within the Si3N4-containing samples, the high-temperature dielectric values and ferroelectric properties seemed to increase with increasing concentrations of Si3N4.

Namsar, Orapim; Watcharapasorn, Anucha; Jiansirisomboon, Sukanda

2010-05-01

66

Self standing nanoparticulate networks by self assembly surfactant H1 mesophase  

NASA Astrophysics Data System (ADS)

We show that nanoparticles (size > 10 nm) that are dispersed in nonionic surfactant/water system, assemble into networks on cooling into the H1 phase, independent of particle surface chemistry. Coating the particles with a crosslinkable polymer, and covalent coupling of the coated particle assemblies in the H1 phase allows us to form free standing particulate networks that are stable after surfactant removal. Thus, dynamic templating of surfactant H1 domains is a facile technique that involves near ambient temperatures, and a benign water wash for template removal. The network mesh size can be varied from the sub-micron to tens of microns by controlling the cooling rate. Particle networks can be flow-oriented prior to crosslinking, and interpenetrating networks can also be formed. We will show examples of macroporous nanoparticulate networks formed using nanoparticles of inorganic oxides, polymer latices, as well as bionanoparticles such as proteins.

Kumaraswamy, Guruswamy; Sharma, Kamendra; Gupta, Sayam Sen

2012-02-01

67

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

68

Novel low voltage and solution processable organic thin film transistors based on water dispersed polymer semiconductor nanoparticulates.  

PubMed

Two novel organic thin film transistor structures that combine a hygroscopic insulator with the use of water-dispersed polymer nanoparticles as the active layer are presented. In the first device structure, the semiconducting layer was fabricated from a nanoparticulate suspension of poly-(3-hexylthiophene) prepared through a mini-emulsion process using sodium dodecyl sulfate as the surfactant whereas a surfactant-free precipitation method has been used for the second device structure. In both cases, fully solution processable transistors have been fabricated in a top gate configuration with hygroscopic poly(4-vinylphenol) as the dielectric layer. Both device structures operate at low voltages (0 to -4V) but exhibit contrasting output characteristics. A systematic study is presented on the effect of surfactant on the synthesis of semiconducting nanoparticles, the formation of thin nanoparticulate films and, consequently, on device performance. PMID:23623401

Darwis, Darmawati; Elkington, Daniel; Ulum, Syahrul; Bryant, Glenn; Belcher, Warwick; Dastoor, Paul; Zhou, Xiaojing

2013-07-01

69

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

70

Nanoparticulate lipid dispersions for bromocriptine delivery: characterization and in vivo study.  

PubMed

The physico-chemical properties and in vivo efficacies of two nanoparticulate systems delivering the antiparkinsonian drug bromocriptine (BC) were compared in the present study. Monoolein Aqueous Dispersions (MADs) and Nanostructured Lipid Carriers (NLCs) were produced and characterized. Cryogenic transmission electron microscopy (cryo-TEM) and X-ray diffraction revealed the morphology of MAD and NLC. Dimensional distribution was determined by Photon Correlation Spectroscopy (PCS) and Sedimentation Field Flow Fractionation (SdFFF). In particular, BC was shown to be encapsulated with high entrapment efficiency both in MAD and in NLC, according to SdFFF combined with HPLC. Two behavioral tests specific for akinesia (bar test) or akinesia/bradykinesia (drag test) were used to compare the effects of the different BC formulations on motor disabilities in 6-hydroxydopamine hemilesioned rats in vivo, a model of Parkinson's disease. Both free BC and BC-NLC reduced the immobility time in the bar test and enhanced the number of steps in the drag test, although the effects of encapsulated BC were longer lasting (5h). Conversely, BC-MAD was ineffective in the bar test and improved stepping activity in the drag test to a much lower degree than those achieved with the other preparations. We conclude that MAD and NLC can encapsulate BC, although only NLC provide long-lasting therapeutic effects possibly extending BC half-life in vivo. PMID:22061262

Esposito, Elisabetta; Mariani, Paolo; Ravani, Laura; Contado, Catia; Volta, Mattia; Bido, Simone; Drechsler, Markus; Mazzoni, Serena; Menegatti, Enea; Morari, Michele; Cortesi, Rita

2012-02-01

71

Deep penetration of nanoparticulate drug delivery systems into tumors: challenges and solutions.  

PubMed

In recent decades, nanoparticulate drug delivery systems have attracted extensive attention in cancer therapy for such appealing properties as small particle size, huge surface area, narrow size distribution and prolonged circulation time. Although several nanomedicines have successfully reached the clinical, evidences have proved that therapeutic efficacy isn't improved significantly, except for better toleration and less side effects. Given that the physiological abnormalities in tumors, multiple biobarriers need to be overcome before nanomedicines are delivered to the target site. Passive targeting nanoparticles ensure nanomedicines' extensive extravasation from tumor vessels via enhanced permeation and retention effect, but the diffusion distance is limited to 2-3 cell layer thicknesses. Active targeting nanoparticles tend to bind the peripheral cells of the tumor mass, hindering nanoparticles further penetration into the tumor core region. Therefore, how to improve the deep penetration of nanomedicines into tumors is a formidable task for achieving the desired anticancer therapeutic efficacy. This review demonstrates the penetration obstacles existing in tumor region for nanoparticles, summarizes the important properties of nanomedicines affecting tumor deep penetration and highlights the solutions to improve tumor deep penetration of nanoparticles. PMID:23651305

Li, L; Sun, J; He, Z

2013-01-01

72

Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans.  

PubMed

The Greenland and Antarctic Ice Sheets cover ~ 10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice Sheet catchment reveal the potential for globally significant export of labile iron fractions to the near-coastal euphotic zone. We estimate that the flux of bioavailable iron associated with glacial runoff is 0.40-2.54 Tg per year in Greenland and 0.06-0.17 Tg per year in Antarctica. Iron fluxes are dominated by a highly reactive and potentially bioavailable nanoparticulate suspended sediment fraction, similar to that identified in Antarctic icebergs. Estimates of labile iron fluxes in meltwater are comparable with aeolian dust fluxes to the oceans surrounding Greenland and Antarctica, and are similarly expected to increase in a warming climate with enhanced melting. PMID:24845560

Hawkings, Jon R; Wadham, Jemma L; Tranter, Martyn; Raiswell, Rob; Benning, Liane G; Statham, Peter J; Tedstone, Andrew; Nienow, Peter; Lee, Katherine; Telling, Jon

2014-01-01

73

Advances in direct oxidation methanol fuel cells  

NASA Technical Reports Server (NTRS)

Fuel cells that can operate directly on fuels such as methanol are attractive for low to medium power applications in view of their low weight and volume relative to other power sources. A liquid feed direct methanol fuel cell has been developed based on a proton exchange membrane electrolyte and Pt/Ru and Pt catalyzed fuel and air/O2 electrodes, respectively. The cell has been shown to deliver significant power outputs at temperatures of 60 to 90 C. The cell voltage is near 0.5 V at 300 mA/cm(exp 2) current density and an operating temperature of 90 C. A deterrent to performance appears to be methanol crossover through the membrane to the oxygen electrode. Further improvements in performance appear possible by minimizing the methanol crossover rate.

Surampudi, S.; Narayanan, S. R.; Vamos, E.; Frank, H.; Halpert, G.; Laconti, Anthony B.; Kosek, J.; Prakash, G. K. Surya; Olah, G. A.

1993-01-01

74

Room temperature ferromagnetism in Eu-doped ZnO nanoparticulate powders prepared by combustion reaction method  

NASA Astrophysics Data System (ADS)

Nanoparticulate powders of Eu-doped ZnO with 1.0, 1.5, 2.0 and 3.0 at% Eu were synthesized by combustion reaction method using zinc nitrate, europium nitrate and urea as fuel without subsequent heat treatments. X-ray diffraction patterns (XRD) of all samples showed broad peaks consistent with the ZnO wurtzite structure. The absence of extra reflections in the diffraction patterns ensures the phase purity, except for x=0.03 that exhibits small reflection corresponding to Eu2O3 phase. The average crystallite size determined from the most prominent (1 0 1) peak of the diffraction using Scherrer's equation was in good agreement with those determined by transmission electron microscopy (TEM); being ~26 nm. The magnetic properties measurements were performed using a vibrating sample magnetometer (VSM) in magnetic fields up to 2.0 kOe at room temperature. The hysteresis loops, typical of magnetic behaviors, indicating that the presence of an ordered magnetic structure can exist in the Eu-doped ZnO wurtzite structure at room temperature. The room temperature ferromagnetism behavior increases with the Eu3+ doping concentration. All samples exhibited the same Curie temperature (TC) around ~726 K, except for x=0.01; TC~643 K. High resolution transmission electron microscopy (HRTEM) images revealed defects/strain in the lattice and grain boundaries of Eu-doped ZnO nanoparticulate powders. The origin of room temperature ferromagnetism in Eu-doped ZnO nanoparticulate powders was discussed in terms of these defects, which increase with the Eu3+ doping concentration.

Franco, A.; Pessoni, H. V. S.; Soares, M. P.

2014-04-01

75

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. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 4336-4345, 2014. 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

76

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

77

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

78

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

79

Biological tolerance of different materials in bulk and nanoparticulate form in a rat model: sarcoma development by nanoparticles  

PubMed Central

In order to study the pathobiological impact of the nanometre-scale of materials, we evaluated the effects of five different materials as nanoparticulate biomaterials in comparison with bulk samples in contact with living tissues. Five groups out of 10 rats were implanted bilaterally for up to 12 months with materials of the same type, namely TiO2, SiO2, Ni, Co and polyvinyl chloride (PVC), subcutaneously with bulk material on one side of the vertebral column and intramuscularly with nanoparticulate material on the contralateral side. At the end of each implantation time, the site was macroscopically examined, followed by histological processing according to standard techniques. Malignant mesenchymal tumours (pleomorphic sarcomas) were obtained in five out of six cases of implanted Co nanoparticle sites, while a preneoplastic lesion was observed in an animal implanted with Co in bulk form. In the Ni group, all animals rapidly developed visible nodules at the implanted sites between 4 and 6 months, which were diagnosed as rhabdomyosarcomas. Since the ratio of surface area to volume did not show significant differences between the Ni/Co group and the TiO2/SiO2/PVC group, we suggested that the induction of neoplasia was not mediated by physical effects, but was mediated by the well-known carcinogenic impact of Ni and Co. The data from the Co group show that the physical properties (particulate versus bulk form) could have a significant influence on the acceleration of the neoplastic process. PMID:17015296

Hansen, Torsten; Clermont, Gaëlle; Alves, Antonio; Eloy, Rosy; Brochhausen, Christoph; Boutrand, Jean Pierre; Gatti, Antonietta M; James Kirkpatrick, C

2006-01-01

80

Nanoparticulate assemblies of amphiphiles and diagnostically active materials for multimodality imaging.  

PubMed

Modern medicine has greatly benefited from recent dramatic improvements in imaging techniques. The observation of physiological events through interactions manipulated at the molecular level offers unique insight into the function (and dysfunction) of the living organism. The tremendous advances in the development of nanoparticulate molecular imaging agents over the past decade have made it possible to noninvasively image the specificity, pharmacokinetic profiles, biodistribution, and therapeutic efficacy of many novel compounds. Several types of nanoparticles have demonstrated utility for biomedical purposes, including inorganic nanocrystals, such as iron oxide, gold, and quantum dots. Moreover, natural nanoparticles, such as viruses, lipoproteins, or apoferritin, as well as hybrid nanostructures composed of inorganic and natural nanoparticles, have been applied broadly. However, among the most investigated nanoparticle platforms for biomedical purposes are lipidic aggregates, such as liposomal nanoparticles, micelles, and microemulsions. Their relative ease of preparation and functionalization, as well as the ready synthetic ability to combine multiple amphiphilic moieties, are the most important reasons for their popularity. Lipid-based nanoparticle platforms allow the inclusion of a variety of imaging agents, ranging from fluorescent molecules to chelated metals and nanocrystals. In recent years, we have created a variety of multifunctional lipid-based nanoparticles for molecular imaging; many are capable of being used with more than one imaging technique (that is, with multimodal imaging ability). These nanoparticles differ in size, morphology, and specificity for biological markers. In this Account, we discuss the development and characterization of five different particles: liposomes, micelles, nanocrystal micelles, lipid-coated silica, and nanocrystal high-density lipoprotein (HDL). We also demonstrate their application for multimodal molecular imaging, with the main focus on magnetic resonance imaging (MRI), optical techniques, and transmission electron microscopy (TEM). The functionalization of the nanoparticles and the modulation of their pharmacokinetics are discussed. Their application for molecular imaging of key processes in cancer and cardiovascular disease are shown. Finally, we discuss a recent development in which the endogenous nanoparticle HDL was modified to carry different diagnostically active nanocrystal cores to enable multimodal imaging of macrophages in experimental atherosclerosis. The multimodal characteristics of the different contrast agent platforms have proven to be extremely valuable for validation purposes and for understanding mechanisms of particle-target interaction at different levels, ranging from the entire organism down to cellular organelles. PMID:19435319

Mulder, Willem J M; Strijkers, Gustav J; van Tilborg, Geralda A F; Cormode, David P; Fayad, Zahi A; Nicolay, Klaas

2009-07-21

81

Approche moléculaire par le procédé sol-gel de nanoparticules de TiO2 dopées et/ou fonctionnalisées : applications en imagerie médicale et en catalyse d'oxydation.  

E-print Network

??Un procédé sol-gel développé au laboratoire a été appliqué à des précurseurs hétéroleptiqueset/ou hétérométalliques pour l’élaboration de nouveaux matériaux hybrides et/ou dopés.Des nanoparticules de TiO2… (more)

Mendez, Violaine

2010-01-01

82

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

83

Coupling of two multistep catalytic cycles for the one-pot synthesis of propargylamines from alcohols and primary amines on a nanoparticulated gold catalyst.  

PubMed

A one-pot reaction was performed with a nanoparticulated gold catalyst. A secondary amine is formed through N-monoalkylation of a primary amine with an alcohol by a borrowing hydrogen methodology in a three-step reaction. The secondary amine formed enters into a second A(3)-coupling cycle to give propargylamines. The multistep reaction requires a gold species formed and stabilized on a ceria surface. PMID:22996294

Corma, Avelino; Navas, Javier; Sabater, María J

2012-10-29

84

Physicochemical characterization and toxicological evaluation of plant-based anionic polymers and their nanoparticulated system for ocular delivery.  

PubMed

The water-soluble fractions of mucilages and gum from the seeds of fenugreek, isphagula and mango bark exudate were isolated, purified and characterized using X-ray diffraction (XRD) spectrometry, Fourier transform infrared spectroscopy (FT-IR), maldi/GC-MS, elemental analysis, 1D ((1)H and (13)C) and 2D (HMQC, COSY) nuclear magnetic resonance spectroscopy (NMR). The fenugreek mucilage was identified to be a galactomannan chain consisting of 4 units of galactose attached to the backbone of 6 mannose units in 1:1.5 ratio. The isphagula mucilage was identified to be an arabinoxylan polysaccharide chain consisting of 4 units of arabinofuranose attached to the backbone of 9 xylopyrannose units in 1:3 ratio. The mango gum showed the presence of amylose, ?-arabinofuranosyl and ?-galactopyranosyl, respectively. The characterized mucilages and gum were individually formulated into nanoparticulate system using their complementarily charged polymer chitosan. The particles were observed to be spherical in shape in the range of 61.5-90 nm having zetapotential between 31 and 34 mV and PDI of 0.097-0.241. The prepared nanoparticles were observed to be nonirritant and nontoxic in vitro and in vivo upto 2000 ?g/ml. Therefore, these mucilages and gum can be the alternatives of anionic polymers for the ocular drug delivery system. PMID:23952497

Pathak, Deepa; Kumar, Prashant; Kuppusamy, Gowthamarajan; Gupta, Ankur; Kamble, Bhagyashree; Wadhwani, Ashish

2014-12-01

85

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

86

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

87

Revisiting the Fundamentals in the Design and Control of Nanoparticulate Colloids in the Frame of Soft Chemistry1  

PubMed Central

This review presents thoughts on some of the fundamental features of conceptual models applied in the design of fine particles in the frames of colloid and soft chemistry. A special emphasis is placed on the limitations of these models, an acknowledgment of which is vital in improving their intricacy and effectiveness in predicting the outcomes of the corresponding experimental settings. Thermodynamics of self-assembly phenomena illustrated on the examples of protein assembly and micellization is analyzed in relation to the previously elaborated thesis that each self-assembly in reality presents a co-assembly, since it implies a mutual reorganization of the assembling system and its immediate environment. Parameters used in the design of fine particles by precipitation are discussed while referring to solubility product, various measures of supersaturation levels, induction time, nucleation and crystal growth rates, interfacial energies, and the Ostwald–Lussac law of phases. Again, the main drawbacks and inadequacies of using the aforementioned parameters in tailoring the materials properties in a soft and colloidal chemical setting were particularly emphasized. The basic and practical limitations of zeta-potential analyses, routinely used to stabilize colloidal dispersions and initiate specific interactions between soft chemical entities, were also outlined. The final section of the paper reiterates the unavoidable presence of practical qualitative models in the design and control of nanoparticulate colloids, which is supported by the overwhelming complexity of quantitative relationships that govern the processes of their formation and assembly. PMID:24490052

Uskokovic, Vuk

2013-01-01

88

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

89

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

PubMed

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

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

2008-04-01

90

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

91

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

Microsoft Academic Search

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

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

2005-01-01

92

Small Molecules and Sum Frequency Generation Probes of Nanoparticulate TiO2  

NASA Astrophysics Data System (ADS)

Anatase TiO2 is known to photo catalytically mineralize a wide variety of pollutants and pathogens, both airborne and in aqueous solution. One of the major benefits of basing water treatment systems on TiO2 is that it is environmentally benign and so non toxic that it is used as a colorant in creamy salad dressing. The primary impediment to wide spread implementation of a TiO2 based system for water decontamination is that the quantum efficiency in contact with condense phase water is less than 5%. Since the quantum efficiency for destruction of airborne materials is greater than 80%, the potential for increased efficiency is very real. To convert the potential to practice, the oxidation mechanism needs to be more fully understood. We will report on the results of using a nonlinear optical spectroscopy, sum frequency generation (SFG) as an in situ probe of interactions at the TiO2 surface. Results suggest that the dominant oxidation mechanism converts from a direct to an indirect mechanism as the water content (vapor pressure) increases. This presentation will discuss the probe technique as well as the results.

Shultz, Mary Jane

2006-03-01

93

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

94

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

PubMed

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

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

2012-04-01

95

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

96

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

97

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

98

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

PubMed

Poor interfacial contact is often encountered in nanoparticulate film-based devices. The dye-sensitized solar cell (DSSC) is a representative case in which a nanoporous TiO(2) electrode needs to be prepared on the transparent conducting oxide (TCO)-coated glass substrate. In this study, we demonstrate that the inter-electrode contact resistance accounts for a considerable portion of the total resistance of a DSSC and its efficiency can be greatly enhanced by welding the interface with a laser. TiO(2) films formed on the TCO-coated glass substrate were irradiated with a pulsed ultraviolet laser beam at 355 nm; this transmits through the TCO and glass but is strongly absorbed by TiO(2). Electron microscopy analysis and impedance measurements showed that a thin continuous TiO(2) layer is formed at the interface as a result of the local melting of TiO(2) nanoparticles and this layer completely bridges the gap between the two electrodes, improving the current flow with a reduced contact resistance. We were able to improve the efficiency by 35-65% with this process. DSSCs fabricated using a homemade TiO(2) paste revealed an efficiency improvement from eta = 3.3% to 5.4%, and an increase from 8.2% to 11.2% was achieved with the TiO(2) electrodes made from a commercial paste. PMID:20671364

Kim, Jinsoo; Kim, Jonghyun; Lee, Myeongkyu

2010-08-27

99

Physicochemical characterization and aerosol dispersion performance of organic solution advanced spray-dried microparticulate/nanoparticulate antibiotic dry powders of tobramycin and azithromycin for pulmonary inhalation aerosol delivery.  

PubMed

The purpose of this study was to systematically design pure antibiotic drug dry powder inhalers (DPIs) for targeted antibiotic pulmonary delivery in the treatment of pulmonary infections and comprehensively correlate the physicochemical properties in the solid-state and spray-drying conditions effects on aerosol dispersion performance as dry powder inhalers (DPIs). The two rationally chosen model antibiotic drugs, tobramycin (TOB) and azithromycin (AZI), represent two different antibiotic drug classes of aminoglycosides and macrolides, respectively. The particle size distributions were narrow, unimodal, and in the microparticulate/nanoparticulate size range. The SD particles possessed relatively spherical particle morphology, smooth surface morphology, low residual water content, and the absence of long-range molecular order. The emitted dose (ED%), fine particle fraction (FPF%) and respirable fraction (RF%) were all excellent. The MMAD values were in the inhalable range (<10 ?m) with smaller MMAD values for SD AZI powders in contrast to SD TOB powders. Positive linear correlations were observed between the aerosol dispersion performance parameter of FPF with increasing spray-drying pump rates and also with the difference between thermal parameters expressed as Tg-To (i.e. the difference between the glass transition temperature and outlet temperature) for SD AZI powders. The aerosol dispersion performance for SD TOB appeared to be influenced by its high water vapor sorption behavior (hygroscopicity) and pump rates or To. Aerosol dispersion performance of SD powders were distinct for both antibiotic drug aerosol systems and also between different pump rates for each system. PMID:24215736

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

2014-02-14

100

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

PubMed

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

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

2013-01-01

101

Microwave-assisted fabrication of nanoparticulate TiO(2) microspheres for synergistic photocatalytic removal of Cr(VI) and methyl orange.  

PubMed

High yield production of micro/nanostructured nanoparticulate TiO2 microspheres (NTMs) via a facile microwave-assisted hydrothermal approach was investigated. The rapid and uniform microwave heating could reduce the reaction time to 30 min, an order of magnitude shorter than that of conventional hydrothermal methods. The characterization data confirmed that the resultant NTMs were highly uniform in size, having an average diameter of ?0.5 ?m. The obtained NTMs were found to be constructed by well-crystallized anatase phase nanoparticles ranging from 5 to 10 nm that can be readily controlled by the microwave radiation temperature. Nitrogen sorption isotherm analysis revealed that the obtained NTMs possessed abundant mesoporous structures with a high specific surface area of 124 m(2) g(-1). An in situ self-aggregation formation process under controllable pH in presence of urea was proposed. The results obtained from the application of NTMs for simultaneous photocatalytic decontamination of Cr(VI) and methyl orange (MO) demonstrated a strong synergistic effect that dramatically enhanced both Cr(VI) reduction and MO oxidation removal efficiencies. This work not only enriched the synthesis methods of the micro/nanostructured TiO2, but also provided a new means to improve the photocatalytic efficiency via structural-induced synergistic effect, applicable to the other catalysis systems. PMID:24433013

Yang, Yong; Wang, Guozhong; Deng, Quan; Ng, Dickon H L; Zhao, Huijun

2014-02-26

102

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

103

Novel silicon and tin alloy nano-particulate materials via spark erosion for high performance and high capacity anodes in lithium ion batteries  

NASA Astrophysics Data System (ADS)

The advent and popularity of portable electronics, as well as the need to reduce carbon-based fuel dependence for environmental and economic reasons, has led to the search for higher energy density portable power storage methods. Lithium ion batteries offer the highest energy density of any portable energy storage technology, but their potential is limited by the currently used materials. Theoretical capacities of silicon (3580 mAh/g) and tin (990 mAh/g) are significantly higher than existing graphitic anodes (372 mAh/g). However, silicon and tin must be scaled down to the nano-level to mitigate the pulverization from drastic volume changes in the anode structure during lithium ion insertion/extraction. The available synthesis techniques for silicon and tin nano-particles are complicated and scale-up is costly. A unique one-step process for synthesizing Si-Sn alloy and Sn nano-particles via spark plasma erosion has been developed to achieve the ideal nano-particulate size and carbon coating architecture. Spark erosion produces crystalline and amorphous spherical nano-particles, averaging 5-500nm in diameter. Several tin and silicon alloys have been spark eroded and thoroughly characterized using SEM, TEM, EDS, XPS, Auger spectroscopy, NMR spectroscopy and TGA. The resulting nano-particles show improved performance as anodes over commercialized materials. In particular, pure sparked Sn particles show stable reversible capacity at ˜460 mAh/g with >99.5% coulombic efficiency for over 100 cycles. These particles are drop-in ready for existing commercial anode processing techniques and by only adding 10% of the sparked Sn particles the total current cell capacity will increase by ˜13%.

White, Emma Marie Hamilton

104

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

105

Preparation and performance of a Nafion ®/montmorillonite nanocomposite membrane for direct methanol fuel cell  

NASA Astrophysics Data System (ADS)

Direct methanol fuel cells (DMFC) have major technical problems, e.g. slow methanol oxidation kinetics and high methanol crossover, to use as power sources for several applications. To overcome these problems it has been proposed to increase the fuel cell operating temperature to over 100-150 °C and to reduce the methanol permeability. In this work, we made Nafion ®/montmorillonite (MMT) nanocomposite membranes and carried out diverse tests. The nanocomposite membranes were produced by direct melt intercalation of perfluorosulfonylfluoride copolymer resin (Nafion ® resin) into the montmorillonite and modified montmorillonite (m-MMT) which was organized by dodecylamine. The membrane-electrode assembly (MEA) has been made using a hot pressing method and the electrode prepared using PtRu black and Pt black catalysts for anode and cathode, respectively. The morphology of the nanocomposite membranes has been investigated using SEM and TEM. The nanocomposite membranes and MMT and m-MMT were analyzed using by FT-IR and X-ray diffraction (XRD). The thermal and mechanical properties of those membranes were also investigated and the methanol permeability was measured by gas chromatography (GC). The performance of the MEA using the nanocomposite membrane was evaluated by single cell test. The results show that the performance of the MEA using the nanocomposite membrane was higher than that of a commercial Nafion ® membrane at high operating temperature.

Jung, D. H.; Cho, S. Y.; Peck, D. H.; Shin, D. R.; Kim, J. S.

106

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

SciTech Connect

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

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

2013-09-26

107

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

NASA Astrophysics Data System (ADS)

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

Xiong, Liufeng

108

Multiferroic nanoparticulate thin film composites by Co implantation of ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal targets  

NASA Astrophysics Data System (ADS)

Two-phase magnetostrictive-piezoelectric thin film composites are key materials to the development of a range of potentially disruptive magnetoelectric technologies, such as electrical-writing magnetic-reading random access memories. However, multiferroic thin film composites prepared so far show neither magnetoelectric switching nor magnetoelectric responses comparable to those of related bulk ceramic materials and cermets. Here we show that ion implantation of magnetic species into ferroelectric single crystal targets can be an effective alternative means of obtaining nanoparticulate thin film composites of this type. Concept is proved by the implantation of Co into a Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal with ultrahigh piezoelectricity. Formation of an ensemble of ferromagnetic nanoparticles embedded in an amorphized layer within the ferroelectric crystal is clearly shown.

Torres, María; Ricote, Jesús; Amorín, Harvey; Jaafar, Miriam; Holgado, Susana; Piqueras, Juan; Asenjo, Agustina; García-Hernández, Mar; Algueró, Miguel

2011-12-01

109

Advance Directives  

MedlinePLUS

... saved articles window. My Saved Articles » My ACS » Advance Directives Download Printable Version [PDF] » An advance health care ... to get started. Why do you need an advance directive? What is an advance directive? Types of advance ...

110

Direct Variation  

NSDL National Science Digital Library

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

2012-01-01

111

Direct formic acid fuel cells  

NASA Astrophysics Data System (ADS)

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

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

112

Advance Directives  

MedlinePLUS

... Yes. Each state has its own laws regarding advance directives. Therefore, special care should be taken to follow the laws of ... may not be recognized in another. State-specific advance directives can be downloaded from ... Organization (see Question 10). 9. What can caregivers ...

113

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

114

Directed polymers versus directed percolation  

NASA Astrophysics Data System (ADS)

Universality plays a central role within the rubric of modern statistical mechanics, wherein an insightful continuum formulation rises above irrelevant microscopic details, capturing essential scaling behaviors. Nevertheless, occasions do arise where the lattice or another discrete aspect can constitute a formidable legacy. Directed polymers in random media, along with its close sibling, directed percolation, provide an intriguing case in point. Indeed, the deep blood relation between these two models may have sabotaged past efforts to fully characterize the Kardar-Parisi-Zhang universality class, to which the directed polymer belongs.

Halpin-Healy, Timothy

1998-10-01

115

Direction 2000.  

ERIC Educational Resources Information Center

Describes the Direction 2000 program at Mary Ward Catholic Secondary School in Toronto, which features large subject resource areas instead of classrooms, a schoolwide computer network developed in conjunction with Unisys Canada, computer education across the curriculum, and an automated approach to information retrieval. (DMM)

Schmidt, Wendy; Sisca, Laila

1992-01-01

116

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.

Houston, Children'S M.

2014-09-19

117

Light, Directly  

NSDL National Science Digital Library

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

118

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

NASA Astrophysics Data System (ADS)

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.; Mohammed, Waleed S.; Dutta, Joydeep

2014-02-01

119

Magnetoelectric effects of nanoparticulate Pb(Zr0.52Ti0.48)O3-NiFe2O4 composite films  

NASA Astrophysics Data System (ADS)

The authors fabricated Pb(Zr0.52Ti0.48)O3-NiFe2O4 composite films consisting of randomly dispersed NiFe2O4 nanoparticles in the Pb(Zr0.52Ti0.48)O3 matrix. The structural analysis revealed that the crystal axes of the NiFe2O4 nanoparticles are aligned with those of the ferroelectric matrix. The composite has good ferroelectric and magnetic properties. The authors measured the transverse and longitudinal components of the magnetoelectric voltage coefficient, which supports the postulate that the magnetoelectric effect comes from direct stress coupling between magnetostrictive NiFe2O4 and piezoelectric Pb(Zr0.52Ti0.48)O3 grains.

Ryu, Hyejin; Murugavel, P.; Lee, J. H.; Chae, S. C.; Noh, T. W.; Oh, Yoon Seok; Kim, Hyung Jin; Kim, Kee Hoon; Jang, Jae Hyuck; Kim, Miyoung; Bae, C.; Park, J.-G.

2006-09-01

120

Detection de nanoparticules dans le milieu interplantaire  

E-print Network

: quantum effects p r h Small heat capacity energy of 1 photon h ~ c T stochastic heating [Draine & Li 2001 light (scattered sunlight) Meteor trails - optical, radar - > 100 m ~ 4 106 kg/year/on Earth Marine

Demoulin, Pascal

121

Characterisation of nanoparticulate systems by hydrodynamic chromatography.  

PubMed

Particle size and particle size distribution can have a fundamental effect on the physical properties of colloidal dispersions. For many systems the measurement of average particle size is not sufficient, the presence of different size populations will have a strong influence on properties and could be related to the production process. Hydrodynamic chromatography (HDC) provides a method for the separation of polymers in solution or particles in suspension based on their size. In a packed column, the separation takes place in the inter-particle channels and the elution order is from large to small, analogous to gel permeation chromatography. The dynamic range of packed column HDC is from molecular size up to particles of greater than 1 microm. New instrumentation which can be used to determine the particle size distribution of a range of colloidal dispersions by packed column HDC is described. Data to support accuracy and precision of average particle size determination is presented as well as a number of case studies to illustrate the applicability of the technique to samples with polydisperse or multi-modal particle size distributions. PMID:12176267

Williams, A; Varela, E; Meehan, E; Tribe, K

2002-08-21

122

Advance care directives  

MedlinePLUS

Living will; Power of attorney; DNR - advance directive; Do not resuscitate - advance directive ... of medical care you should receive. Using an advance directive, you can tell your doctor what medical treatment ...

123

Direct WIMP detection in directional experiments  

SciTech Connect

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

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

2007-03-01

124

DIRECT INTERNET DATA Troubleshooting  

E-print Network

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

Ashley, Michael C. B.

125

Advance Directives (Psychiatric)  

MedlinePLUS

... org/ (800) 950-NAMI; info@nami.org ©2014 Advance Directives by Ronald S. Honberg National Director for Policy and ... psychosurgery from their scope. Laws specifically authorizing psychiatric advance directives have been enacted in twelve states. The first ...

126

Directed energy architectures  

Microsoft Academic Search

This report discusses the roles directed energy could play in strategic defense, assesses their likely effectiveness, and outlines the important complementarity between directed and kinetic energy, which appears to be pivotal to the development of robust defenses. Directed energy concepts could provide adequate kill rates that are relatively insensitive to fast, compact launches. Midcourse applications are based on the robust

Canavan

1988-01-01

127

CONVERGENCE OF ASYMPTOTIC DIRECTIONS  

Microsoft Academic Search

We study convergence properties of asymptotic directions of un- bounded sets in normed spaces. The links between the continuity of a set- valued map and the convergence of asymptotic directions are examined. The results are applied to investigate continuity properties of marginal functions and asymptotic directions of level sets.

DINH THE LUC; JEAN-PAUL PENOT

128

Preparation and characterization of a PtRu\\/C nanocatalyst for direct methanol fuel cells  

Microsoft Academic Search

PtRu\\/C nanocatalysts were prepared by changing the molar ratio of citric acid to platinum and ruthenium metal salts (CA:PtRu) from 1:1, 2:1, 3:1 to 4:1 using sodium borohydride as a reducing agent. Transmission electron microscopy analysis indicated that well-dispersed smaller PtRu particles (2.6nm) were obtained when the molar ratio was maintained at 1:1. X-ray diffraction analysis confirmed the formation of

J. W. Guo; T. S. Zhao; J. Prabhuram; R. Chen; C. W. Wong

2005-01-01

129

Direct marketing attitudes  

Microsoft Academic Search

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

Daulatram Lund; Pradeep K. Korgaonkar

1995-01-01

130

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

131

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

132

Directed energy overview  

Microsoft Academic Search

Directed energy weapons can add significantly to the effectiveness of a Strategic Defense System (SDS) by complementing the capabilty of phase I kinetic energy weapons. Component development for each of the directed energy concepts is progressing well. The chemical laser and neutral particle beam programs are nearing the stage where component integration tests are essential for establishing engineering proof-of-principle. For

Neil Griff

1990-01-01

133

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.

134

Highly directional acoustic receivers.  

PubMed

The theoretical directivity of a single combined acoustic receiver, a device that can measure many quantities of an acoustic field at a collocated point, is presented here. The formulation is developed using a Taylor series expansion of acoustic pressure about the origin of a Cartesian coordinate system. For example, the quantities measured by a second-order combined receiver, denoted a dyadic sensor, are acoustic pressure, the three orthogonal components of acoustic particle velocity, and the nine spatial gradients of the velocity vector. The power series expansion, which can be of any order, is cast into an expression that defines the directivity of a single receiving element. It is shown that a single highly directional dyadic sensor can have a directivity index of up to 9.5 dB. However, there is a price to pay with highly directive sensors; these sensors can be significantly more sensitive to nonacoustic noise sources. PMID:12656387

Cray, Benjamin A; Evora, Victor M; Nuttall, Albert H

2003-03-01

135

Directive Type General Order  

E-print Network

of the College of Charleston community. The Crime Prevention Coordinator will report directly to the Deputy in the residence areas (and all other Campus locations); · Department sponsored/led Rape Aggression Defense (RA

Kasman, Alex

136

Catheter-Directed Thrombolysis  

MedlinePLUS

... directly to the blood clot. by positioning a mechanical device at the site to break up the ... dissolving medication, by breaking it up with a mechanical device, or both. To treat the clot with ...

137

Lyapunov Direction Fields.  

National Technical Information Service (NTIS)

Linearization around the chaotic orbits of dynamical systems offers good prospects for understanding complex systems. The naturally available information that can be obtained from such studies are the magnitudes and directions in phase space of stretching...

J. M. Greene, J. S. Kim

1986-01-01

138

AISI direct steelmaking program  

SciTech Connect

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

Aukrust, E.

1991-01-09

139

Comprehension of Navigation Directions.  

National Technical Information Service (NTIS)

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 ...

A. F. Healy, V. I. Schneider

2002-01-01

140

Direct Antiglobulin Test  

MedlinePLUS

... the cause of hemolytic anemia as caused by autoimmune disease or induced by drugs; to investigate a transfusion ... may become attached to antigens on RBCs: With autoimmune diseases and other conditions : Some people make antibodies directed ...

141

Direct conversion technology  

Microsoft Academic Search

The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period

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

1988-01-01

142

Direct conversion technology  

Microsoft Academic Search

The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal Magnetohydrodynamic Electrical Generator (LMMHD) for the period January 1,

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

1989-01-01

143

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

144

Directed forgetting in monkeys  

Microsoft Academic Search

Based on several recent demonstrations of a directed forgetting effect in pigeons, three experiments were carried out in an\\u000a attempt to demonstrate directed forgetting in three squirrel monkeys. During initial training with a delayed matching-to-sample\\u000a procedure, retention tests were always given for sample stimuli followed by remember cues (R-cues) and were always omitted\\u000a for sample stimuli followed by forget cues

William A. Roberts; Dwight S. Mazmanian; Philipp J. Kraemer

1984-01-01

145

Electrohydrodynamic direct-writing  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

146

Directed network modules  

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

147

Direct conversion technology  

NASA Astrophysics Data System (ADS)

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

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

1989-12-01

148

Directed energy overview  

NASA Astrophysics Data System (ADS)

Directed energy weapons can add significantly to the effectiveness of a Strategic Defense System (SDS) by complementing the capabilty of phase I kinetic energy weapons. Component development for each of the directed energy concepts is progressing well. The chemical laser and neutral particle beam programs are nearing the stage where component integration tests are essential for establishing engineering proof-of-principle. For the somewhat less mature ground-based free electron laser technology, device development will be emphasized during the next several years. Development of the acquisition, tracking and pointing (ATP) program will continue at a fast pace, with an exciting proof-of-principle test to occur in space in early 1990. The directed energy program remains on track to provide information to support a national decision on strategic defense in the 1991/1993 timeframe.

Griff, Neil

1990-06-01

149

Direct conversion technology  

SciTech Connect

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

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

1992-01-07

150

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

151

Modelling directional solidification  

NASA Technical Reports Server (NTRS)

This grant, NAG8-831, was a continuation of a previous grant, NAG8-541. The long range goal of this program has been to develop an improved understanding of phenomena of importance to directional solidification, in order to enable explanation and prediction of differences in behavior between solidification on Earth and in space. Emphasis in the recently completed grant was on determining the influence of perturbations on directional solidification of InSb and InSb-GaSb alloys. In particular, the objective was to determine the influence of spin-up/spin-down (ACRT), electric current pulses and vibrations on compositional homogeneity and grain size.

Wilcox, William R.; Regel, Liya L.

1994-01-01

152

Direct Conversion Technology  

SciTech Connect

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

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

1992-07-01

153

Direct thrombin inhibitors.  

PubMed

Direct thrombin inhibitors interact with thrombin and block its catalytic activity on a wide range of substrates. Their action is in contrast to heparin and its derivatives, which inhibit thrombin and other coagulation serine proteases via antithrombin, and to the warfarin-type drugs that interfere with synthesis of the precursors of the coagulation serine proteases. There are three direct thrombin inhibitors approved for clinical use at present (lepirudin, bivalirudin, argatroban) and another in advanced clinical testing (melagatran/ximelagatran). The chemical structure, kinetics of thrombin inhibition, pharmacokinetics, and clinical use of each of these agents are discussed. PMID:12124681

Kaplan, Karen L; Francis, Charles W

2002-07-01

154

Directed Relativistic Blast Wave  

E-print Network

A spherically symmetrical ultra-relativistic blast wave is not an attractor of a generic asymmetric explosion. Spherical symmetry is reached only by the time the blast wave slows down to non-relativistic velocities, when the Sedov-Taylor-von Neumann attractor solution sets in. We show however, that a directed relativistic explosion, with the explosion momentum close to the explosion energy, produces a blast wave with a universal intermediate asymptotic -- a selfsimilar directed ultra-relativistic blast wave. This universality might be of interest for the astrophysics of gamma-ray burst afterglows.

Andrei Gruzinov

2007-04-23

155

Dragonfly directional sensor  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

156

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

157

RECUEIL OFFICIEL RGLEMENTS, DIRECTIVES,  

E-print Network

____________________________________________________________ DIRECTIVE RELATIVE Adoption � L'UTILISATION DU Date : Délibération : COURRIER �LECTRONIQUE 19990315 courrier électronique (courriel) est maintenant devenu un outil de travail usuel. Ses avantages sont copies de sécurité des serveurs de courrier électronique de l'Université. Les règles de conservation des

Leclercq, Remi

158

Direct Detection of Exoplanets  

Microsoft Academic Search

Direct detection of exoplanets from the ground is now within reach of existing astronomical instruments. Indeed, a few planet candidates have already been imaged and analyzed and the capability to detect (through imaging or interferometry) young, hot, Jupiter-mass planets exists. We present here an overview of what such detection methods can be expected to do in the near and far

J.-L. Beuzit; D. Mouillet; B. R. Oppenheimer; J. D. Monnier

2007-01-01

159

School Direct application  

E-print Network

Training Programme (salaried) will open from early November from the Department for Education's website and the School Direct Training Programme (salaried) will be open from early November. There will be one single at www.education.gov.uk/teachschooldirect. The system will show the number of places offered by each lead

160

Implementing the WEEE Directive  

Microsoft Academic Search

During the 1980s, industrialised countries in Europe experienced a shortage of landfills. This lead National Governments and EU authorities to investigate regulations to direct waste streams to recycling and incineration. Besides packaging, cars and batteries, waste from electronic and electric products was identified as a major component of the generic waste stream which could be easily diverted to alternative processes

K. Hieronymi

2001-01-01

161

Reservoir sedimentation: planning directives  

Microsoft Academic Search

This paper aims at providing dam planners with broad directives regarding sediment-related problems that need to be addressed during the planning and design stages of a dam. It is meant to give the planner and the designer a perspective of the investigations which are required as well as the limitations of existing theories and techniques for analysing and solving problems.

ALBERT ROOSEBOOM

162

Direct Versus Indirect Competition.  

ERIC Educational Resources Information Center

Competition in sport and physical education programs has been used to motivate the learning of skills, increase physical fitness, and to create environments purportedly conducive to the development of desirable personality qualities. However, the way in which competition is conceptualized is of great importance. In direct competition, achievement…

Billing, John

163

Direct from CDC's Environmental  

E-print Network

for the environmental health practice community: The American College of Veterinary Preventive Medicine requires health as "the sum of all contributions to the physical, mental, and social well-being of humans through Direct from CDC's Environmental Health Services Branch Hugh Mainzer, M.S, D

164

Generalized Partial Directed Coherence  

Microsoft Academic Search

This paper re-examines the definition of partial directed coherence (PDC) which was recently introduced as a linear frequency-domain quantifier of the multivariate relationship between simultaneously observed time series for application in functional connectivity inference in neuroscience. The present reappraisal aims at improving PDC's performance under scenarios that involve severely unbalanced predictive modelling errors (innovations noise). The present modification turns out

L. A. Baccald; F. de Medicina

2007-01-01

165

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.

2012-08-08

166

Directed Brokerage and \\  

Microsoft Academic Search

Recent pronouncements by the Department of Labor and the SEC have onceagain focused the attention of the pension community on soft dollar and directedbrokerage arrangements. The article examines new concerns surrounding such arrangements in light of the fiduciary responsibility provisions of ERISA, emphasizing the duties of plan sponsors and money managers in monitoring investment and execution decisions and in directing

Donald J. Myers

1987-01-01

167

Syntax Directed Transduction  

Microsoft Academic Search

A transduction is a mapping from one set of sequences to another. A syntax directed transduction is a particular type of transduction which is defined on the grammar of a context free language and which is meant to be a model of part of the translation process used in many compilers. The transduction is considered from an automata theory viewpoint

Philip M. Lewis II; Richard Edwin Stearns

1966-01-01

168

Syntax-Directed Transduction  

Microsoft Academic Search

A transduction is a mapping from one set of sequences to another. A syntax-directed transduction is a particular type of transduction which is defined on the grammar of a context-free language and which is meant to be a model of part of the translation process used in many compilers. The transduction is considered from an automata theory viewpoint as specifying

Philip M. Lewis II; Richard Edwin Stearns

1968-01-01

169

Directed evolution of biocatalysts  

Microsoft Academic Search

Directed evolution is being used increasingly in academic and industrial laboratories to modify and improve important biocatalysts. Significant advances during this period of review include compartmentalization of genes and the in vitro translation apparatus in emulsions, as well as several impressive demonstrations of catalyst improvement. Shuffling of homologous genes offers a new way to utilize natural diversity in the evolution

Frances H Arnold; Alexander A Volkov

1999-01-01

170

Is Direct Mail Dead?  

ERIC Educational Resources Information Center

Varied approaches taken to bringing vitality to direct mail fundraising campaigns are described for 10 institutions: Northern Arizona University, Georgetown University (District of Columbia); Miami University (Ohio), Kansas University, Pennsylvania State University, St. Ignatius High School (Ohio); Metropolitan State University (Minnesota),…

Hauk, Jeff; Burdenski, Robert A.

1998-01-01

171

Is there directional smelling?  

Microsoft Academic Search

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

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

1989-01-01

172

Core Directions in HRD.  

ERIC Educational Resources Information Center

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

1996

173

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

174

The Four Directions  

ERIC Educational Resources Information Center

This article presents the Native American cultural symbol, the Four Directions, as a sign that is culturally evident and inter-tribally significant. Through understanding the significance of the symbol, a deeper understanding is possible for non-Natives, especially an understanding of the Native Americans' relationship between their artwork and…

Willis, Steve

2005-01-01

175

[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

176

Directional Spherical Cherenkov Detector  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

177

Topologies on directed graphs  

NASA Technical Reports Server (NTRS)

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

Lieberman, R. N.

1972-01-01

178

Direct magnetic resonance arthrography.  

PubMed

Magnetic resonance (MR) arthrography has gained increasing popularity as a diagnostic tool in the assessment of intra-articular derangements. Its role has been studied extensively in the shoulder, but it also has been explored in the hip, elbow, knee, wrist and ankle. This article reviews the current role of direct MR arthrography in several major joints, with consideration of pertinent anatomy, techniques and applications. PMID:15351900

Elentuck, Dmitry; Palmer, William E

2004-11-01

179

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

180

Future directions for QCD  

SciTech Connect

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

Bjorken, J.D.

1996-10-01

181

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

182

Pneumatic Directional Control Valves  

NSDL National Science Digital Library

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

Bartelt, Terry L.; Tomlin, Bonnie

2008-11-24

183

Direct and Inverse Variation  

NSDL National Science Digital Library

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

Media, Annenberg

2009-12-23

184

Direct subnanosecond voltage monitors  

SciTech Connect

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

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

1981-01-01

185

Directed vapor deposition  

Microsoft Academic Search

This dissertation describes the invention, design, construction, experimental evaluation and modeling of a new physical vapor deposition technique (U.S. Patent #5,534,314) for high rate, efficient deposition of refractory elements, alloys, and compounds onto flat or curved surfaces. The new Directed Vapor Deposition (DVD) technique examined in this dissertation was distinct from previous physical vapor deposition techniques because it used low

James Frederick Groves

1998-01-01

186

Direct conversion technology  

NASA Astrophysics Data System (ADS)

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

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

1988-12-01

187

Direct observation detonator operation  

NASA Astrophysics Data System (ADS)

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

Hall, Charles R.

2001-11-01

188

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

189

DIRECT INTERNET DATA User's Guide  

E-print Network

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

Ashley, Michael C. B.

190

Visual direction finding by fishes  

NASA Technical Reports Server (NTRS)

The use of visual orientation, in the absence of landmarks, for underwater direction finding exercises by fishes is reviewed. Celestial directional clues observed directly near the water surface or indirectly at an asymptatic depth are suggested as possible orientation aids.

Waterman, T. H.

1972-01-01

191

Psychiatric Advance Directives: Getting Started  

MedlinePLUS

... Home Getting Started National Resource Center on Psychiatric Advance Directives - Getting Started Getting Started Psychiatric advance directives (PADs) are relatively new legal instruments that may ...

192

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

193

Direct reading inductance meter  

NASA Technical Reports Server (NTRS)

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

Kolby, R. B. (inventor)

1977-01-01

194

Omni-directional railguns  

SciTech Connect

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

Shahinpoor, M.

1994-12-31

195

Pulmonary rehabilitation: future directions.  

PubMed

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

Nici, Linda; ZuWallack, Richard L

2014-06-01

196

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

197

Mandating advance directives.  

PubMed

As the population ages, end-of-life care (EOLC) costs become an increasingly pressing subject. Advance directives (ADs) are legal documents that allow individuals to convey their decisions about EOLC. Although ADs have been shown to reduce EOLC costs, most people do not have ADs. To address this issue, we propose that Congress instruct the Centers for Medicare and Medicaid Services to collect ADs from Medicare beneficiaries. Because ADs can improve care and reduce unnecessary spending, this solution would likely be attractive to a broad coalition of support from providers, insurers, and the public. PMID:24293349

Eltorai, Adam E M; Besdine, Richard W

2014-06-01

198

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

199

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, development of the first prototype named the Visible Alpha Tool (VAT) that uses visible spectrum illumination of 532 nm, assist in design of second prototype tool named the DUV Alpha Tool (DAT) using deep UV (266 nm) illumination, and continuing support of nLine in the development of higher throughput commercial tools.

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

2003-06-15

200

Direct Production of Copper  

NASA Astrophysics Data System (ADS)

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

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

1987-09-01

201

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

202

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

203

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

204

Directed quantum communication  

E-print Network

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

Johan Aberg; Stefan Hengl; Renato Renner

2009-10-09

205

Task directed sensing  

NASA Technical Reports Server (NTRS)

High-level robot control research must confront the limitations imposed by real sensors if robots are to be controlled effectively in the real world. In particular, sensor limitations make it impossible to maintain a complete, detailed world model of the situation surrounding the robot. To address the problems involved in planning with the resulting incomplete and uncertain world models, traditional robot control architectures must be altered significantly. Task-directed sensing and control is suggested as a way of coping with world model limitations by focusing sensing and analysis resources on only those parts of the world relevant to the robot's active goals. The RAP adaptive execution system is used as an example of a control architecture designed to deploy sensing resources in this way to accomplish both action and knowledge goals.

Firby, R. James

1990-01-01

206

Speech research directions  

SciTech Connect

This paper presents an overview of the current activities in speech research. The authors discuss the state of the art in speech coding, text-to-speech synthesis, speech recognition, and speaker recognition. In the speech coding area, current algorithms perform well at bit rates down to 9.6 kb/s, and the research is directed at bringing the rate for high-quality speech coding down to 2.4 kb/s. In text-to-speech synthesis, what we currently are able to produce is very intelligible but not yet completely natural. Current research aims at providing higher quality and intelligibility to the synthetic speech that these systems produce. Finally, today's systems for speech and speaker recognition provide excellent performance on limited tasks; i.e., limited vocabulary, modest syntax, small talker populations, constrained inputs, etc.

Atal, B.S.; Rabiner, L.R.

1986-09-01

207

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

208

Fiber optic TV direct  

NASA Astrophysics Data System (ADS)

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

Kassak, John E.

1991-12-01

209

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

210

Census of directional drilling contractors  

SciTech Connect

This paper discusses directional drilling of pipeline crossings which is an environmentally responsible, cost-effective method of pipeline construction. Modern directional drilling rigs can place pipelines under rivers, streams, highways and other sensitive areas where conventional construction methods would be too expensive or even prohibited. A group of 11 pipeline contractors that use trenchless technology recently formed the Directional Crossing Contractors Association to promote the directional crossing industry. Any contractor with experience in directional crossings can apply for membership in the DCCA. Any individual or firm in the business of furnishing materials, supplies, equipment or other services to directional crossing contractors can apply for associate membership.

Not Available

1991-10-01

211

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

212

Direct Detection of Exoplanets  

NASA Astrophysics Data System (ADS)

Direct detection of exoplanets from the ground is now within reach of existing astronomical instruments. Indeed, a few planet candidates have already been imaged and analyzed and the capability to detect (through imaging or interferometry) young, hot, Jupiter-mass planets exists. We present here an overview of what such detection methods can be expected to do in the near and far term. These methods will provide qualitatively new information about exoplanets, including spectroscopic data that will mature the study of exoplanets into a new field of comparative exoplanetary science. Spectroscopic study of exoplanet atmospheres promises to reveal aspects of atmospheric physics and chemistry as well as internal structure. Astrometric measurements will complete orbital element determinations partially known from the radial velocity surveys. We discuss the impact of these techniques, on three different timescales, corresponding to the currently available instruments, the new "Planet Finder" systems under development for 8- to 10-m telescopes, foreseen to be in operation in 5-10 years, and the more ambitious but more distant projects at the horizon of 2020.

Beuzit, J.-L.; Mouillet, D.; Oppenheimer, B. R.; Monnier, J. D.

213

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

214

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

215

New directions in Guatemala.  

PubMed

This news brief relates some new directions, since its inception in 1988, which the Family Welfare Association of Guatemala (APROFAM) will be undertaking during 1996-97. In December 1997, APROFAM restructured its program to include reproductive health services with family planning services. The program will target rural Mayan communities. The program will be working toward service sustainability, due to reduced external support. In October 1996 a new board was established that will focus on marketing, IEC, finance and administration, rural development, and clinical services. Meetings between the new board of directors of APROFAM and JOICFP focused on the use of integrated programs as a model for widespread programming among the rural Mayan population. The integrated program that was implemented by JOICFP was successful in reaching Mayan communities of Solola. This population was difficult to reach with conventional family planning approaches. The integrated program was successful in establishing trust with and participation of the rural Mayans. Activities such as parasite control, skills training, and income generation for women were useful in establishing trust and promoting self-reliance. Integrated programs will refocus on family planning and developing self-reliance. The UNFPA will be conducting an annual internal evaluation as a means of sharing information and deepening understanding of project implementation. PMID:12292085

1997-02-01

216

Efficient multi-site-directed mutagenesis directly from genomic template.  

PubMed

In this article, the traditional multi-site-directed mutagenesis method based on overlap extension PCR was improved specifically for complicated templates, such as genomic sequence or complementary DNA. This method was effectively applied for multi-site-directed mutagenesis directly from mouse genomic DNA, as well as for combination, deletion or insertion of DNA fragments. PMID:23151786

Luo, Fengtao; Du, Xiaolan; Weng, Tujun; Wen, Xuan; Huang, Junlan; Chen, Lin

2012-12-01

217

Comparison of Principal Diffusion Directions Using Directional Statistics  

E-print Network

­ commonly analyzed scalars derived from DT ­ ignore 3D orientation · Diffusion-weighted single-shot SE EPIComparison of Principal Diffusion Directions Using Directional Statistics Armin Schwartzman, Robert, California, USA To establish a formal methodology of group comparisons for DTI direction maps. ·Diffusion

Dougherty, Bob

218

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

219

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...

220

Dual-nanoparticulate-reinforced aluminum matrix composite materials  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

221

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

222

Polymerizable nanoparticulate silica-reinforced calcium phosphate bone cement.  

PubMed

Bone cements based on calcium phosphate powder and different concentrations of colloidal silica suspensions were developed. Setting time and washout behavior of the cements were recorded and compared with those of a control group prepared by the same powder phase and distilled water as liquid. The phase composition, compressive strength, and morphology of the cements were determined after incubation and soaking in simulated body fluid. Proliferation of osteoblasts seeded on samples was also determined as a function of time. The results showed that the long setting time, poor compressive strength, and undesirable washout behavior of the cement made with distilled water were considerably improved by adding colloidal silica in a dose-dependent manner. On the basis of XRD and SEM results, both control group and nanosilica-added cements composed of nanosized apatite flakes after 7 days soaking, in addition to tetracalcium phosphate residual for the latter. It was found that the rate of hydraulic reactions that are responsible for conversion of the cement reactants to nanostructured apatite was increased by the presence of colloidal silica. Furthermore, the osteoblasts exhibited better proliferation on nanosilica added cements compared to control one. This study suggests better applied properties for nanosilica-added calcium phosphate cement compared to traditional cements. PMID:22706926

Hesaraki, Saeed; Alizadeh, Masoud; Borhan, Shokoufeh; Pourbaghi-Masouleh, Milad

2012-08-01

223

Photoproduction of iodine with nanoparticulate semiconductors and insulators  

PubMed Central

The crystal structures of different forms of TiO2 and those of BaTiO3, ZnO, SnO2, WO3, CuO, Fe2O3, Fe3O4, ZrO2 and Al2O3 nanoparticles have been deduced by powder X-ray diffraction. Their optical edges have been obtained by UV-visible diffuse reflectance spectra. The photocatalytic activities of these oxides and also those of SiO2 and SiO2 porous to oxidize iodide ion have been determined and compared. The relationships between the photocatalytic activities of the studied oxides and the illumination time, wavelength of illumination, concentration of iodide ion, airflow rate, photon flux, pH, etc., have been obtained. Use of acetonitrile as medium favors the photogeneration of iodine. PMID:21679411

2011-01-01

224

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

2012-01-01

225

Paclitaxel loaded PEGylated gleceryl monooleate based nanoparticulate carriers in chemotherapy.  

PubMed

A PEGylated drug delivery system of paclitaxel (PTX), based on glyceryl monooleate (GMO) was prepared by optimizing various parameters to explore its potential in anticancer therapy. The prepared system was characterized through polarized light microscopy, TEM, AFM and SAXS to reveal its liquid crystalline nature. As GMO based LCNPs exhibit high hemolytic toxicity and faster release of entrapped drug (66.2 ± 2.5% in 24 h), PEGylation strategy was utilized to increase the hemocompatibility (reduction in hemolysis from 60.3 ± 10.2 to 4.4 ± 1.3%) and control the release of PTX (43.6 ± 3.2% released in 24 h). The cytotoxic potential and cellular uptake was assessed in MCF-7 cell lines. Further, biodistribution studies were carried out in EAT (Ehrlich Ascites tumor) bearing mice using (99m)Tc-(Technetium radionuclide) labeled formulations and an enhanced circulation time and tumor accumulation (14 and 8 times, respectively) were observed with PEGylated carriers over plain ones, at 24 h. Finally, tumor growth inhibition experiment was performed and after 15 days, control group exhibited 15 times enhancement in tumor volume, while plain and PEGylated systems exhibited only 8 and 4 times enhancement, respectively, as compared to initial tumor volume. The results suggest that PEGylation enhances the hemocompatibility and efficacy of GMO based system that may serve as an efficient i.v. delivery vehicle for paclitaxel. PMID:22809646

Jain, Vikas; Swarnakar, Nitin K; Mishra, Prabhat R; Verma, Ashwni; Kaul, Ankur; Mishra, Anil K; Jain, Narendra K

2012-10-01

226

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

227

Increased osteoblast adhesion on nanoparticulate crystalline hydroxyapatite functionalized with KRSR  

PubMed Central

The present in vitro study created nanometer crystalline hydroxyapatite (HA) and amorphous calcium phosphate for novel orthopedic applications. Specifically, nano-crystalline HA and amorphous calcium phosphate nanoparticles were synthesized by a wet chemical process followed by hydrothermal treatment for 2 hours at 200°C and 70°C, respectively. Resulting particles were then pressed into compacts. For the preparation of control conventional HA particles (or those currently used in orthopedics with micron diameters), the aforementioned calcium phosphate particles were pressed into compacts and sintered at 1100°C for 2 hours. All calcium phosphate-based particles were fully characterized. Results showed that although there was an initial weight gain for all the compacts studied in this experiment, higher eventual degradation rates up to 3 weeks were observed for nano-amorphous calcium phosphate compared with nano-crystalline HA which was higher than conventional HA. Peptide functionalization (with the cell adhesive peptide lysine-arginine-serine-arginine [KRSR] and the non-cell-adhesive peptide lysine-serine-arginine-arginine [KSRR]) was accomplished by means of a three-step reaction procedure: silanization with 3-aminopropyltriethoxysilane (APTES), cross-linking with N-succinimidyl-3-maleimido propionate (SMP), and finally peptide immobilization. The peptide functionalization was fully characterized. Results demonstrated increased osteoblast (bone-forming cell) adhesion on non-functionalized and functionalized nano-crystalline HA compacts compared with nano amorphous calcium phosphate compacts; both increased osteoblast adhesion compared with conventional HA. To further exemplify the novel properties of nano crystalline HA, results also showed similar osteoblast adhesion between non-functionalized nano crystalline HA and KRSR functionalized conventional HA. Thus, results provided evidence that nanocrystalline HA should be further studied for orthopedic applications. PMID:17717974

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

2006-01-01

228

Self-Directed Workplace Learning.  

ERIC Educational Resources Information Center

This document contains four papers from a symposium on self-directed workplace learning. "Self-Directed Work Teams: Implementation and Performance" (Marcel van der Klink, Hilde ter Horst) discusses the results of a study examining the implementation and effects of self-directed work teams in a land register office and the role of the department's…

1998

229

Fault branching and rupture directivity  

Microsoft Academic Search

Could the directivity of a complex earthquake be inferred from the ruptured fault branches it created? Typically, branches develop in forward orientation, making acute angles relative to the propagation direction. Direct backward branching of the same style as the main rupture (e.g., both right lateral) is disallowed by the stress field at the rupture front. Here we propose another mechanism

Sonia Fliss; Harsha S. Bhat; Renata Dmowska; James R. Rice

2005-01-01

230

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

231

New directions at NSF  

NASA Astrophysics Data System (ADS)

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

Harvey, Albert B.

1995-10-01

232

A Change of Direction  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released July 21, 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

In this image we can clearly see a major change in wind regimes. The classic yardang form occupies the top of the image. These older yardangs were formed by a NW/SE wind regime. The younger, smaller yardangs are forming in the rest of the image from a NE/SW wind. The age relationship is readily visible at the intersection area, where the large yardangs are being cut crosswise into NE/SW aligned forms. The top framelet of this image has vertical black/white lines caused by charge on the camera CCD.

Image information: VIS instrument. Latitude -6.3, Longitude 183.8 East (176.2 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

233

Preferential sliding directions on graphite  

NASA Astrophysics Data System (ADS)

The anisotropy of friction on graphitic surfaces is investigated by a combined friction force microscopy and modeling study. Friction vectors deviate up to 15° from pulling directions. The strongest deviations are found for pulling directions which lie almost along one zigzag direction of the honeycomb structure, the preferred sliding direction on graphite surfaces and epitaxial graphene grown on SiC(0001). Atomic stick-slip events along and across molecular rows determine direction and magnitude of friction. Simulation and modeling reveal the role of temperature and of the two-dimensional character of the surface potential for the friction anisotropy.

Balakrishna, S. G.; de Wijn, Astrid S.; Bennewitz, Roland

2014-06-01

234

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

NASA Astrophysics Data System (ADS)

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

La Torre Riveros, Lyda

235

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

236

Dynamic behaviors in directed networks  

SciTech Connect

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

Park, Sung Min [Center of Complex Systems, Samsung Economic Research Institute, Seoul 140-702 (Korea, Republic of); Kim, Beom Jun [Department of Physics, BK21 Physics Research Division, and Institute of Basic Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2006-08-15

237

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

E-print Network

Schools." Athletics Rowan has one of the strongest NCAA Division III athletics programs in the nation building, a new $45 million science center, one of the newest and largest student recreation centersFor directions go to: www.rowan.edu/directions Academics Students have access to the resources

Rusu, Adrian

238

Median recoil direction as a WIMP directional detection signal  

SciTech Connect

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

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

2010-03-15

239

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 ...

240

Policy Procedure Administrative Directive Title: _____________________________________  

E-print Network

Policy ­ Procedure ­ Administrative Directive Title: _____________________________________ Policy-President _____________ See also: Related Policies, Procedures and Agreements: Relevant Legislation and Regulations: ____________________________________________________________________________ Background and Purpose: ____________________________________________________________________________ Policy

Northern British Columbia, University of

241

Direct cooled power electronics substrate  

DOEpatents

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

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

2010-09-14

242

High CO tolerance of Pt/Ru nanocatalyst: Insight from first principles calculations  

NASA Astrophysics Data System (ADS)

Density functional theory based calculations of the energetics of adsorption and diffusion of CO on Pt islets and on the Ru(0001) substrate show that the CO has the lowest adsorption energy at the center of the islet and its bonding increases as it moves to the edge of the island and further onto the substrate. Activation energy barriers for CO diffusion from the islet to the Ru surface are found to be lower than 0.3 eV making the process feasible and leading to the conclusion that this hydrogen oxidation catalyst is CO tolerant because of the spillover of CO from active Pt sites to the Ru substrate. The rate of CO oxidation by OH is found to be substantially enhanced when the former is adsorbed on the edge of Pt islands and the latter on nearby Ru sites.

Stolbov, Sergey; Ortigoza, Marisol Alcántara; Adzic, Radoslav; Rahman, Talat S.

2009-03-01

243

High CO Tolerance of Pt/Ru Nanocatalyst: Insight from First Principles Calculations  

SciTech Connect

Density functional theory based calculations of the energetics of adsorption and diffusion of CO on Pt islets and on the Ru(0001) substrate show that CO has the lowest adsorption energy at the center of the islet, and its bonding increases as it moves to the edge of the island and further onto the substrate. Activation energy barriers for CO diffusion from the islet to the Ru surface are found to be lower than 0.3 eV making the process feasible and leading to the conclusion that this hydrogen oxidation catalyst is CO tolerant because of the spillover of CO from active Pt sites to the Ru substrate. We present the rationale for this effect using insights from detailed electronic structure calculations.

Adzic, R.; Stolbov, S.; Ortigoza, M.; Rahman, T.S.

2009-03-31

244

Trust, autonomy, and advance directives  

Microsoft Academic Search

Trust has been largely ignored in contemporary bioethical discussions and also by courts of law. The favored language of autonomy, privacy, and rights is useful but insufficient to speak to moral experience, especially the experience of persons who write advance directives, but also physicians who receive such directives. The Brophy case is analyzed for its salient features, and a more

Larry R. Churchill

1989-01-01

245

Direct Marketing Goes to College.  

ERIC Educational Resources Information Center

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

Merante, Joseph A.

1980-01-01

246

Subtle Gaze Direction REYNOLD BAILEY  

E-print Network

, digital media offers the opportunity for active control of the gaze pattern. This paper demonstrates a viewer's gaze about a digital image. We call this paradigm subtle gaze direction. Subtle gaze direction movements may depend on the viewer's intent or task [Yarbus 1967] [Henderson and Hollingworth 1998]. Image

Grimm, Cindy

247

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

248

Critical dimensions of directional couplers  

Microsoft Academic Search

The critical dimensions of directional couplers include the waveguide separation at the coupling position, the coupling length, and the bending radius of the waveguides. This paper focuses on discussing the waveguide separation at the coupling position. Two directional couplers have been developed with different waveguide separation. The relationship between the waveguide separation and the performance of the couplers has been

Shuming Yang; Xiangqian Jiang; Graeme Maxwell

2010-01-01

249

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

250

NDBC's digital directional wave module  

Microsoft Academic Search

The National Data Buoy Center (NDBC) has developed a compact, low power, directional wave measurement system called the Digital Directional Wave Module (DDWM). It represents the latest advance in NDBC's 30-year history of producing wave measurement systems. The DDWM consists of embedded electronics; a commercial off-the-shelf (COTS) motion sensor; custom, embedded software and hardware; and a mounting plate. The COTS

Chung-Chu Teng; Richard Bouchard; Rodney Riley; Theodore Mettlach; Richard Dinoso; Joel Chaffin

2009-01-01

251

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

252

Direct catastrophic injury in sports.  

PubMed

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

Boden, Barry P

2005-11-01

253

Directions  

E-print Network

Apr 13, 2013 ... Workshop on inverse problems in scattering and imaging ... They will give you a parking voucher at the front desk and you can move your car across ... plain looking, rectangular building which is the tallest building on campus.

254

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

2013-01-01

255

Module bay with directed flow  

DOEpatents

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

Torczynski, John R. (Albuquerque, NM)

2001-02-27

256

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

257

Directions to Huntersdale Virginia Water  

E-print Network

Directions to Huntersdale Camberley Virginia Water PRUNE HILL A30 A30 LONDON ROAD BAKEHAM LANE. By road from Virginia Water 1 Follow the B389 Christchurch Road and continue past the station and parade

Royal Holloway, University of London

258

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

259

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

260

Nonimaging radiant energy direction device  

DOEpatents

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

Winston, Roland (Chicago, IL)

1980-01-01

261

Laser Direct Drive: Scientific Advances,  

E-print Network

Mission Indirect Drive (Chosen path for NIF) Laser Beams x-rays Hohlraum Pellet Direct Drive (IFE) Laser by Chris Ebbers Thursday PM Mercury DPPSL Laser (LLNL) = 351 nm (tripled) Solid State Laser #12;6 We

262

Quantum direct communication with authentication  

SciTech Connect

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

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

2006-04-15

263

Direct Broadcast Satellite: Radio Program  

Microsoft Academic Search

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

James E. Hollansworth

1992-01-01

264

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

2008-02-23

265

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

266

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

267

Review on Non-directional Direct Dark Matter Searches  

NASA Astrophysics Data System (ADS)

An overview of non-directional direct detection methods is given. The currently leading experiments for spin independent WIMPs interactions are using simultaneous measurement of two quantities for event-by-event background discrimination in cryogenic bolometers and noble gas like xenon. Besides these, several interesting techniques have been developped, each having a specific advantage concerning e.g. energy threshold lowering or strong immunity to ionizing radiations background. Technologies used and most recent results about spin-dependent and spin-independent cases are presented.

Censier, B.

2012-02-01

268

"Let Me Be Direct": Using Direct Assessments with Student Leaders  

ERIC Educational Resources Information Center

A primary goal of assessment is to deliver truthful and clear information that can be used to inform and improve outcomes. Although there are multiple ways to achieve this goal, common approaches can be broken down into two major categories: (1) direct assessment; and (2) indirect assessment. Indirect assessment typically relies on general…

Lindsay, Nathan; Hourigan, Aimee; Smist, Jennifer; Wray, Larry

2013-01-01

269

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

270

Directions for improved fusion reactors  

SciTech Connect

Conceptual fusion reactor studies over the past 10 to 15 years have projected systems that may be too large, complex, and costly to be of commercial interest. One main direction for improved fusion reactors points towards smaller, higher-power-density approaches. First-order economic issues (i.e., unit direct cost and cost of electricity) are used to support the need for more compact fusion reactors. A generic fusion physics/engineering/costing model is used to provide a quantiative basis for these arguments for specific fusion concepts.

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

1986-01-01

271

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

272

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

273

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

274

Direct flow crystal growth system  

DOEpatents

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

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

1992-01-01

275

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

276

The Progressive Riding Series Directions  

E-print Network

to and employment in the industry. Members may enroll for each unit as many times as desired and may progress the direct supervision of Extension Agents and Leaders. Age requirements for completing the riding units according to their interests and abilities. Many will not advance beyond the first or second levels

Liskiewicz, Maciej

277

Direct immunofluorescent labeling of cells.  

PubMed

In the direct immunofluorescent labeling technique, fluorochrome-labeled antibodies are used as probes for particular antigens or biomolecules. Cells, usually after appropriate fixation, are incubated with the antibodies to which fluorochromes have been directly conjugated. Following incubation, excess antibody is washed off with PBS and the cells are mounted on coverslips with antifade mounting medium. Immunofluorescent labeled cells are analyzed using a conventional fluorescence microscope or by confocal microscopy. Direct labeling has two major advantages: it requires only a single incubation with the labeled reagent, decreasing the number of steps in the staining procedure; and more importantly, provides minimal nonspecific staining and less background. Additionally, the direct labeling technique allows the use of two or more primary antibodies of the same species or isotype, avoiding the problems with secondary antibody staining. This method has multiple applications: to label simultaneously two or more antigens within the same cell or tissue sections; to characterize the subcellular distribution of biomolecules of interest, by concurrently labeling with antibodies to both the antigen of interest and to a known organelle; to investigate whether several antigens of interest are colocalized; and to phenotype cells, for which no specific markers are available, using an appropriate panel of antibodies. PMID:20012827

Pástor, Maria Veronica Dávila

2010-01-01

278

Solar powered direct osmosis desalination  

Microsoft Academic Search

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

Rashid A. Khaydarov; Renat R. Khaydarov

2007-01-01

279

Survey on Directed Model Checking  

Microsoft Academic Search

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

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

2008-01-01

280

Directing Performers for the Cameras.  

ERIC Educational Resources Information Center

An excellent way for an undergraduate, novice director of television and film to pick up background experience in directing performers for cameras is by participating in nonbroadcast-film activities, such as theatre, dance, and variety acts, both as performer and as director. This document describes the varieties of activities, including creative,…

Wilson, George P., Jr.

281

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

282

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

283

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

284

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

285

EMPLOYEE PAYROLL DIRECT DEPOSIT AUTHORIZATION  

E-print Network

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

286

Corps of Engineers Priorities & Direction  

E-print Network

U.S. Army Corps of Engineers Priorities & Direction Commander's Intent My intent is that USACE.mil/ http://www.goarmy.com/ "Built on Values, Standards & Trust" A Leader in STEM "The U.S. Army Corps Lieutenant General, U.S. Army Commanding ® ARMY STRONG® ESSAYONS! #12;Deliver Sustainable Solutions � Deliver

US Army Corps of Engineers

287

Direct asymmetric ?-hydroxylation of ?-hydroxyketones  

Microsoft Academic Search

Direct oxidation of racemic ?-hydroxyketones 1a-c under Sharpless oxidation conditions resulted in the enantiomeric ?,?-dihydroxyketones 2a in 97% ee, 2b in 86% ee and 2c in 95% ee respectively, in 37–58% of isolated yield. The oxidation is assumed to proceed via an allylic enolate intermediate.

Margus Lopp; Anne Paju; Tõnis Kanger; Tõnis Pehk

1997-01-01

288

Does Direct Instruction Cause Delinquency?  

ERIC Educational Resources Information Center

Takes issue with the High/Scope Educational Research Foundation report (Schweinhart, Weikart and Larner, 1986) indicating that preschoolers taught by direct instruction end up with twice the rate of delinquency of children who participated in High/Scope's own kind of preschool education. Argues that self-report methodology invalidates High/Scope…

Bereiter, Carl

1986-01-01

289

Training of Direct Service Staff.  

ERIC Educational Resources Information Center

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

Wallace, Teri, Ed.; And Others

1992-01-01

290

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

291

The Internet: Trends and Directions.  

ERIC Educational Resources Information Center

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

Anderson, Byron

1996-01-01

292

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

293

Bulk Hydrogen Strategic Directions for  

E-print Network

Bulk Hydrogen Storage Strategic Directions for Hydrogen Delivery Workshop May 7-8, 2003 Crystal City, Virginia #12;Breakout Session - Bulk Hydrogen Storage Main Themes/Caveats Bulk Storage = Anything-board storage Uncertainty about evolution of infrastructure requires multiple pathways to be considered Bulk

294

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

295

Sampling properties of directed networks  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

296

Entrance Counseling Guide for Direct Loan Borrowers  

ERIC Educational Resources Information Center

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

Federal Student Aid, US Department of Education, 2010

2010-01-01

297

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

298

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

ERIC Educational Resources Information Center

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

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

2012-01-01

299

GENE LOOPS ENHANCE TRANSCRIPTIONAL DIRECTIONALITY  

PubMed Central

Eukaryotic genomes are extensively transcribed, forming both messenger (m) and noncoding (nc) RNAs. ncRNAs made by RNA polymerase II (Pol II) often initiate from bidirectional promoters (nucleosome-depleted chromatin) that synthesise mRNA and ncRNA in opposite directions. We demonstrate that actively transcribed mRNA encoding genes by adopting a gene loop conformation, restrict divergent transcription of ncRNAs. Since gene loop formation depends on a protein factor (Ssu72) that co-associates with both promoter and terminator, its inactivation leads to increased synthesis of promoter-associated divergent ncRNAs, referred to as Ssu72 restricted transcripts (SRT). Similarly, inactivation of individual gene loops by gene mutation enhances SRT synthesis. We demonstrate that gene loop conformation enforces transcriptional directionality on otherwise bidirectional promoters. PMID:23019609

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

2012-01-01

300

Gene loops enhance transcriptional directionality.  

PubMed

Eukaryotic genomes are extensively transcribed, forming both messenger RNAs (mRNAs) and noncoding RNAs (ncRNAs). ncRNAs made by RNA polymerase II often initiate from bidirectional promoters (nucleosome-depleted chromatin) that synthesize mRNA and ncRNA in opposite directions. We demonstrate that, by adopting a gene-loop conformation, actively transcribed mRNA encoding genes restrict divergent transcription of ncRNAs. Because gene-loop formation depends on a protein factor (Ssu72) that coassociates with both the promoter and the terminator, the inactivation of Ssu72 leads to increased synthesis of promoter-associated divergent ncRNAs, referred to as Ssu72-restricted transcripts (SRTs). Similarly, inactivation of individual gene loops by gene mutation enhances SRT synthesis. We demonstrate that gene-loop conformation enforces transcriptional directionality on otherwise bidirectional promoters. PMID:23019609

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

2012-11-01

301

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

302

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

303

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

Doug MacGugan

2013-08-22

304

Volumetric direct nuclear pumped laser  

NASA Technical Reports Server (NTRS)

A volumetric direct nuclear pumped laser was developed in which the gas is a mixture of He-3 and a minority gas from the group of argon, krypton, xenon, chlorine and fluorine. The mixture of He-3 and the minority gas produces lasing with a minority gas concentration of from 0.01 to 10 percent argon, 1 percent krypton, 0.01 to 5 percent xenon and small concentrations of chlorine or fluorine.

Jalufka, N. W.; Hohl, F.; Deyoung, R. J.; Williams, M. D. (inventors)

1978-01-01

305

Direct search for dark matter  

SciTech Connect

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

Yoo, Jonghee; /Fermilab

2009-12-01

306

Direct generation of optical vortices  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

307

Future directions in desktop video  

Microsoft Academic Search

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

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

1989-01-01

308

Superior Biocatalysts by Directed Evolution  

Microsoft Academic Search

Useful biocatalysts for organic chemistry can be created by directed evolution.Mutations are introduced into genes encoding\\u000a biocatalyst proteins of interest by error-prone PCR or other random mutagenesis methods. The mutated genes can be rearranged\\u000a by recombinative processes like DNA shuffling, thereby significantly enhancing the efficiency with which genes can be evolved.\\u000a These genes are expressed in suitable microbial hosts leading

Manfred T. Reetz; Karl-Erich Jaeger

309

Development of Direct Mastering System  

NASA Astrophysics Data System (ADS)

We have developed a direct mastering system that, without the use of electroforming, processes a photoresist on a nickel substrate and forms a stamper directly on the substrate. An anchor coat is formed on the nickel substrate, on top of which are photoresist bumps formed using photolithography technology. The photoresist bumps and anchor coat are exposed to UV light and processed by high-temperature baking, cross-linking the two layers and firmly adhering them together. Punching both the inner and outer diameters then completes the stamper. A sample stamper was manufactured and used to mold digital versatile discs (DVDs). The DVDs showed an approximately 6.4% base jitter, well within the margin of 8% set in the specification. Furthermore, even after molding 100,000 DVDs, we found no change in either the stamper or the jitter value. Compared to conventional methods, this direct mastering method uses only half the number of processes and requires one-third the amount of processing time, realizing a turn-key solution for mastering which contributes greatly to high throughput and overall cost reductions.

Sano, Kazuhiko; Miyakita, Hakaru

2003-11-01

310

Directional Darwinian Selection in proteins  

PubMed Central

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

2013-01-01

311

Wellbore inertial directional surveying system  

DOEpatents

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

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

1982-09-08

312

Do ants make direct comparisons?  

PubMed Central

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

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

2009-01-01

313

Direct reciprocity in structured populations  

PubMed Central

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

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

2012-01-01

314

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

315

Wellbore inertial directional surveying system  

DOEpatents

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

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

1991-01-01

316

5 CFR 330.402 - Direct recruitment.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Direct recruitment. 330.402 Section 330...CIVIL SERVICE REGULATIONS RECRUITMENT, SELECTION, AND PLACEMENT (GENERAL...Eligibles § 330.402 Direct recruitment. In direct recruitment...

2010-01-01

317

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

318

Directed Discovery of Crystal Structures  

NSDL National Science Digital Library

This contribution is modified from a published exercise "Directed Discovery of Crystal Structures Using Ball-and-Stick Models" [Mogk, 1997] . While the published exercise is based on student exploration of traditional ball-and-stick models of crystal structures, this modified version uses a similar "discovery-based" approach and the latest online crystallographic information and visualization software to teach the spatial relationships and crystal-chemical rules that govern the crystal structures of common minerals and crystalline solids. A few changes in the content have been made from the published exercise, mainly to accommodate the new digital media.

Mogk, Dave; Ratajeski, Kent

319

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

320

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

321

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

322

Direct measure of quantum correlation  

SciTech Connect

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

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

2011-12-15

323

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

324

Motion with direction and balance.  

PubMed

In this issue of Neuron, three papers, Severi et al. (2014), Thiele et al. (2014), and Wang and McLean (2014), examine the descending circuitry involved in coordinating locomotor behavior in larval zebrafish. Visually evoked locomotor and steering movements in zebrafish are mediated by neurons in the nucleus of the medial longitudinal fascicle (nMLF) that project directly to spinal motoneurons. The final motor output induced by nMLF will involve integration in the hindbrain and premotor circuits in the spinal cord. PMID:25102557

El Manira, Abdel; Grillner, Sten

2014-08-01

325

Urologic robots and future directions  

E-print Network

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

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

2008-01-01

326

Semantics of directly manipulating spatializations.  

PubMed

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

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

2013-12-01

327

Illumination direction from texture shading.  

PubMed

We investigate the ability of human observers to judge the direction of illumination from image texture. Photographs of 61 real surfaces were used, taken from the Columbia-Utrecht Reflectance and Texture (Curet) database (http:/www.cs.columbia.edu/CAVE/curet). All samples were normally viewed but obliquely illuminated, the elevation of the source being 22.5 degrees, 45.0 degrees, or 67.5 degrees. The illumination was with a collimated, parallel beam. Stimuli were presented in random orientation, and observers had to judge both the elevation and the azimuth of the source. Observers judged the azimuth within approximately 15 degrees, except for the fact that they committed random (with approximately 50% probability) sign flips (180 degrees flips). Connected with this finding is the fact that observers judged the illumination to be from above rather than below in the overwhelming majority of cases, despite the fact that each case occurred with equal probability. The elevation of the illumination can be judged to some extent but is not far above chance level. The data are in good agreement with a simple model that bases the estimate of illumination direction on the second-order statistics of local luminance gradients. This locates the locus of the probable mechanism very early in the visual stream. PMID:12801166

Koenderink, Jan J; van Doorn, Andrea J; Kappers, Astrid M L; te Pas, Susan F; Pont, Sylvia C

2003-06-01

328

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

329

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

330

Direct visualization of magnetoelectric domains  

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

331

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

332

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

333

Electrochimica Acta 50 (2005) 14131422 Variations in interfacial properties during cell conditioning and  

E-print Network

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

334

Current Developments in Self-Directed Learning.  

ERIC Educational Resources Information Center

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

Long, Huey B.; And Others

335

Training Needs of Direct Support Staff  

ERIC Educational Resources Information Center

Training needs and current status of training for direct support staff were identified in one southeastern state. Data sources were (a) direct support staff, (b) administrators of direct support staff, and (c) consumers with developmental disabilities. Stratified sampling was used to gather data from 108 administrators and 170 direct support staff…

Test, David W.; Flowers, Claudia; Hewitt, Amy; Solow, Jill

2004-01-01

336

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

337

Direct band gap silicon allotropes.  

PubMed

Elemental silicon has a large impact on the economy of the modern world and is of fundamental importance in the technological field, particularly in solar cell industry. The great demand of society for new clean energy and the shortcomings of the current silicon solar cells are calling for new materials that can make full use of the solar power. In this paper, six metastable allotropes of silicon with direct or quasidirect band gaps of 0.39-1.25 eV are predicted by ab initio calculations at ambient pressure. Five of them possess band gaps within the optimal range for high converting efficiency from solar energy to electric power and also have better optical properties than the Si-I phase. These Si structures with different band gaps could be applied to multiple p-n junction photovoltaic modules. PMID:24971657

Wang, Qianqian; Xu, Bo; Sun, Jian; Liu, Hanyu; Zhao, Zhisheng; Yu, Dongli; Fan, Changzeng; He, Julong

2014-07-16

338

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

339

Direct characterization of quantum dynamics.  

PubMed

The characterization of quantum dynamics is a fundamental and central task in quantum mechanics. This task is typically addressed by quantum process tomography (QPT). Here we present an alternative "direct characterization of quantum dynamics" (DCQD) algorithm. In contrast to all known QPT methods, this algorithm relies on error-detection techniques and does not require any quantum state tomography. We illustrate that, by construction, the DCQD algorithm can be applied to the task of obtaining partial information about quantum dynamics. Furthermore, we argue that the DCQD algorithm is experimentally implementable in a variety of prominent quantum-information processing systems, and show how it can be realized in photonic systems with present day technology. PMID:17155454

Mohseni, M; Lidar, D A

2006-10-27

340

New directions in HIV healthcare.  

PubMed

The Canadian Association for HIV Research (CAHR) is the professional organization for HIV and AIDS research in Canada or by Canadians. The theme of CAHR 2011 was "Honoring our history, embracing our diversity", and highlighted the strengths that our diverse communities bring to the fight against HIV/AIDS, and more specifically, the important research data presented that reflect the new direction in which HIV research is focused: to regularize the daily life of the HIV-infected patients. Clinical research in the field of HIV has evolved from developing medication to ensure the patients' survival, to the present where survival is assumed and life events are investigated. This article will cover the research presented in the clinical track and will focus on two issues that are going to impact the future of HIV-infected individuals: cognitive health and child conception. PMID:21810049

Potter, Martin; Lebouche, Bertrand

2011-07-01

341

Directed actin assembly and motility.  

PubMed

The actin cytoskeleton is a key component of the cellular architecture. However, understanding actin organization and dynamics in vivo is a complex challenge. Reconstitution of actin structures in vitro, in simplified media, allows one to pinpoint the cellular biochemical components and their molecular interactions underlying the architecture and dynamics of the actin network. Previously, little was known about the extent to which geometrical constraints influence the dynamic ultrastructure of these networks. Therefore, in order to study the balance between biochemical and geometrical control of complex actin organization, we used the innovative methodologies of UV and laser patterning to design a wide repertoire of nucleation geometries from which we assembled branched actin networks. Using these methods, we were able to reconstitute complex actin network organizations, closely related to cellular architecture, to precisely direct and control their 3D connections. This methodology mimics the actin networks encountered in cells and can serve in the fabrication of innovative bioinspired systems. PMID:24630113

Boujemaa-Paterski, Rajaa; Galland, Rémi; Suarez, Cristian; Guérin, Christophe; Théry, Manuel; Blanchoin, Laurent

2014-01-01

342

Identifying Contienents, Oceans, and Directions  

NSDL National Science Digital Library

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

Ms.bingham

2007-11-06

343

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

344

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

345

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

346

Gold-catalyzed direct arylation.  

PubMed

Biaryls (two directly connected aromatic rings, Ar(1)-Ar(2)) are common motifs in pharmaceuticals, agrochemicals, and organic materials. Current methods for establishing the Ar(1)-Ar(2) bond are dominated by the cross-coupling of aryl halides (Ar(1)-X) with aryl metallics (Ar(2)-M). We report that, in the presence of 1 to 2 mole percent of a gold catalyst and a mild oxidant, a wide range of arenes (Ar(1)-H) undergo site-selective arylation by arylsilanes (Ar(2)-SiMe(3)) to generate biaryls (Ar(1)-Ar(2)), with little or no homocoupling (Ar(1)-Ar(1)/Ar(2)-Ar(2)). Catalysis proceeds at room temperature and tolerates a broad range of functional groups, including those incompatible with cross-coupling. These features expedite biaryl preparation, as demonstrated by synthesis of the nonsteroidal anti-inflammatory diflunisal. PMID:23019647

Ball, Liam T; Lloyd-Jones, Guy C; Russell, Christopher A

2012-09-28

347

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

348

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

349

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

350

Direct detector for terahertz radiation  

DOEpatents

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

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

2008-09-02

351

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

352

Direct N-body Simulations  

NASA Astrophysics Data System (ADS)

Simulations of dense stellar systems, such as globular clusters and galactic nuclei, have never yet been very realistic. Simplifying assumptions, such as used in Fokker-Planck codes or gas models, have allowed us to model large particle numbers at the expense of a loss of detail in local many-body interactions and the imposition of global symmetry constraints. Conversely, direct N-body integration, while far more accurate, has labored under a lack of computer speed needed to model a million stars. The good news is that we will soon be approaching effective computer speeds in the Petaflops range, which will allow us to model the gravitational million-body problem with full realism, at least on the level of point particles. Adding equally realistic stellar evolution and hydrodynamics will be no problem as far as the necessary computer speed is concerned. When the hardware bottleneck will thus be removed, the software bottleneck for realistic cluster simulations will soon become painfully obvious. This is the bad news. While some serious uncertainties remain in the science needed to improve the software, currently the main bottleneck is neither science nor computer speed, but rather a sufficiently robust implementation of already available knowledge.

Hut, P.

2006-08-01

353

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

354

Interface Reconstruction with Directional Walking  

SciTech Connect

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

Yao, J

2009-05-22

355

Direct Deposit _Job Aid March 2012 Page 1 of 7 Direct Deposit Online Instructions Job Aid  

E-print Network

Direct Deposit _Job Aid March 2012 Page 1 of 7 Direct Deposit Online Instructions ­ Job Aid of this job aid is to provide you with the steps to add, edit or inactivate your direct deposit information Deposit within Self Service in PAC. Direct Deposit myColumbia Portal PAC Links #12;Direct Deposit _Job Aid

Grishok, Alla

356

Integrating Directional Links with Omni-Directional Tactical MANET Stack: An Experimental Analysis  

E-print Network

Integrating Directional Links with Omni-Directional Tactical MANET Stack: An Experimental Analysis of OMNI directional tactical MANET with directional links Integration approach of directional capability MANET nodes operate over multiple frequency channels CNL routing: Operate OSPF and flooding link state

Yousefi'zadeh, Homayoun

357

Jet directions in Seyfert galaxies  

E-print Network

We present the study of the relative angle between the accretion disk (or radio jet) and the galaxy disk for a sample of Seyfert galaxies selected from a mostly isotropic property, the 60$\\mu$m flux. For each galaxy we have a pair of points ($i$,$\\delta$), which are the inclination of the galaxy relative to the line of sight and the angle between the jet projected into the plane of the sky and the host galaxy major axis, respectively. This data is combined with a statistical technique to determine the distribution of $\\beta$ angles {\\it in 3 dimensions}, the angle between the jet and the host galaxy plane axis. The analysis of the data, not differentiating between Seyfert 1's and 2's, showed that the observed distribution of $i$ and $\\delta$ values can be well represented by a homogeneous $\\beta-$distribution in the range $0^{\\circ}\\leq\\beta\\leq90^{\\circ}$. However, when we distinguished between Seyfert 1's and 2's, the models could not represent Seyfert 1's adequately. It was necessary to introduce viewing angle restrictions, that a galaxy can only be recognized as a Seyfert 1 if the angle between the jet and the line of sight ($|\\phi|$) is smaller than a given angle $\\phi_c$ and that the galaxy inclination $i$ is smaller than an angle $i_c$, in order to have statistically acceptable models. This is a direct and independent confirmation of the underlying concepts of the Unified Model. We discuss several ways to explain the misalignment between the accretion disk axis and the host galaxy disk axis.

A. L. Kinney; H. R. Schmitt; C. J. Clarke; J. E. Pringle; J. S. Ulvestad; R. R. J. Antonucci

2000-02-06

358

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

359

Direct Contact Detonation Explosives Metal Forming.  

National Technical Information Service (NTIS)

The forming of hemispheres from flat circular metal blanks by the use of compression forming dies and nitroguanidine detonated in direct contact with the workpiece is described. Direct contact detonation effects are discussed. Relationships between workpi...

J. Savitt, R. E. Conover

1965-01-01

360

Directional intercept factor of truncated CPCs  

SciTech Connect

The fraction of power reaching the collector of a truncated cylindrical compound parabolic concentrator, out of the total power arriving at its entry aperture in a given direction, is calculated without ray tracing for all directions.

Minano, J.C.

1983-09-01

361

Training needs of direct support staff.  

PubMed

Training needs and current status of training for direct support staff were identified in one southeastern state. Data sources were (a) direct support staff, (b) administrators of direct support staff, and (c) consumers with developmental disabilities. Stratified sampling was used to gather data from 108 administrators and 170 direct support staff utilizing mail surveys and from 179 focus group participants (56 administrators, 53 direct support staff, and 70 consumers). Findings suggest that direct support staff recognized the needs (a) for additional training on Community Support Skill Standards; (b) to develop a comprehensive, cost-efficient statewide system for training direct support staff; and (c) to develop the role of direct support staff into a valued profession. PMID:15335260

Test, David W; Flowers, Claudia; Hewitt, Amy; Solow, Jill

2004-10-01

362

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...

363

Directed Random Graphs with Given Degree Distributions  

E-print Network

Directed Random Graphs with Given Degree Distributions Ningyuan Chen and Mariana Olvera such as the World Wide Web (WWW)1 or the Twitter network we propose a model for generating a simple directed random

Olvera-Cravioto, Mariana

364

Advance Directives - Multiple Languages: MedlinePlus  

MedlinePLUS

... sharing features on this page, please enable JavaScript. Advance Directives - Multiple Languages Arabic (???????) Chinese - Simplified (????) Chinese - ... ???????) Somali (af Soomaali) Spanish (español) Arabic (???????) Advance Directives (Arabic) ????????? ??????? - ??????? Bilingual PDF Health Information ...

365

Teaching Learners To Be Self-Directed  

Microsoft Academic Search

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

Gerald O. Grow

1991-01-01

366

Terahertz pipe-waveguide-based directional couplers.  

PubMed

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

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

2011-12-19

367

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

368

Self Directed Learning and Self Management. Symposium.  

ERIC Educational Resources Information Center

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

2002

369

Theoretical Foundations for Self-Directed Learning.  

ERIC Educational Resources Information Center

Although a copious body of research literature concerning the practice of adult self-directed learning exists, the theoretical dimension remains undernourished and poorly developed. If a theory for self-directed learning is to be developed, educators have to decide what is the critical element among the three words in the term self-directed

Long, Huey B.

370

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

371

Advance Directives and Do Not Resuscitate Orders  

MedlinePLUS

... A durable power of attorney (DPA) for health care is another kind of advance directive. A DPA states whom you have chosen to ... I have an advance directive? By creating an advance directive, you are making your preferences about medical care known before you're faced with a serious ...

372

DIRECTED ENERGY WEAPONS (DEWs): A BIBLIOGRAPHY  

E-print Network

DIRECTED ENERGY WEAPONS (DEWs): A BIBLIOGRAPHY Compiled by Greta E. Marlatt Dudley Knox Library://www.nps.edu/Library/Research%20Tools/Bibliographies/index.html #12;DIRECTED ENERGY WEAPONS (DEWs): A BIBLIOGRAPHY Complied INTENTIONALLY LEFT BLANK #12;4 Table of Contents DIRECTED ENERGY WEAPONS GENERAL

373

MAPPING DIRECTLY IMAGED GIANT EXOPLANETS  

SciTech Connect

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

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

2013-01-01

374

Future directions of ecosystem science  

USGS Publications Warehouse

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

Baron, Jill; Galvin, Kathleen A.

1990-01-01

375

AIRTV: Broadband Direct to Aircraft  

NASA Astrophysics Data System (ADS)

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

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

2002-01-01

376

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

377

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.

378

Chapter 25: Electromagnetic Waves 6. The figure shows the direction of propagation, direction of the electric  

E-print Network

25 ­ 1 Chapter 25: Electromagnetic Waves 6. The figure shows the direction of propagation, direction of the electric field, and/or the direction of the magnetic field for four electromagnetic waves direction. 9. The figure at the right shows three electromagnetic waves with various orientations

Kioussis, Nicholas

379

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

380

Bedform alignment in directionally varying flows  

USGS Publications Warehouse

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

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

1987-01-01

381

Direct fitness for dynamic kin selection.  

PubMed

The direct-fitness approach to modelling the evolution of social traits is an alternative to the classical inclusive-fitness-based approach. Despite both its utility and popularity, the direct-fitness approach has not yet been extended to include the analysis of dynamic traits, i.e. traits whose level of expression may vary over time. In this article, I apply the direct-fitness approach to cope with the evolution of a dynamic resource-allocation behaviour when this behaviour influences the fitness of relatives. I am able to implement the direct-fitness approach using components (reproductive value, fitness changes and measures of relatedness) found in standard, social-evolutionary models. I illustrate the modified direct-fitness model with an example studied by previous authors, and I show how the direct-fitness perspective can aid the validation of analytical results by means of a genetic algorithm. PMID:21585585

Wild, G

2011-07-01

382

Directional detection of dark matter streams  

E-print Network

Directional detection of WIMPs, in which the energies and directions of the recoiling nuclei are measured, currently presents the only prospect for probing the local \\textit{velocity} distribution of Galactic dark matter. We investigate the extent to which future directional detectors would be capable of probing dark matter substructure in the form of streams. We analyse the signal expected from a Sagittarius-like stream and also explore the full parameter space of stream speed, direction, dispersion and density. Using a combination of non-parametric directional statistics, a profile likelihood ratio test and Bayesian parameter inference we find that within acceptable exposure times ($\\mathcal{O}(10)$ 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

2014-01-01

383

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

384

Directivity measurements of the violin during performance  

NASA Astrophysics Data System (ADS)

Many studies have shown that directivity of musical instruments is significant for the perceived sound within the hall and for performer's ease of hearing each other. The directivity patterns explain in part the differences between many common or special orchestral stage plots. Measurements of the violin's directivity have been performed using an acoustical intensimetry procedure. The precise directivity characteristics of isolated tones have been compared with the mean directivity resulting from performance of four extracts chosen among the orchestral repertoire. Results, which were measured in both horizontal and vertical planes, show interesting differences between the average directivity of each test. They lead to links with few important distinctions in the traditional violin's positions inside the orchestra.

Hardy, Jean-François; Migneron, Jean-Gabriel

2005-04-01

385

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

386

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

387

AGRICULTURAL DIRECT MARKETING AND RURAL DEVELOPMENT  

Microsoft Academic Search

AAgricultural direct marketing implies the selling of agricultural, mainly horticultural products directly to the public either through on-farm markets (farm-shops), community-based farmers’ markets, or post, electronic mail and internet web order. These types of distribution channels can supply customers with fresh, ripen and healthy produce without the physical and social costs of transportation. In our view direct marketing alone is

RADULY ISTVAN; PARTENIE DUMBRAVA

2009-01-01

388

[Case of sudden asystole during direct laryngoscopy].  

PubMed

A 78-year-old man, weighing 74 kg and 172 cm in height suddenly developed asystole during direct laryngoscopy. His heart started beating soon after chest compressions. Direct larygoscopy can stimulate the vagal nerve of the larynx. Although a gradual decrease in heart rate ordinarily occurs prior to asystole, few reports describe the sudden asystole during direct laryngoscopy. Intravenous injection of atropine could avoid the adverse event. Anesthesiologists should pay attention to the occurence of asystole and prepare for resuscitation. PMID:25199323

Okubo, Haruka; Hara, Koji; Sata, Takeyoshi

2014-08-01

389

MANUFACTURING LOGISTICS RESEARCH: TAXONOMY AND DIRECTIONS  

E-print Network

MANUFACTURING LOGISTICS RESEARCH: TAXONOMY AND DIRECTIONS S. DAVID WU Lehigh University, Bethlehem formed in the workshop. To convey this vision we suggest a taxonomy that characterizes research problems

Wu, David

390

17 CFR 38.607 - Direct access.  

... DESIGNATED CONTRACT MARKETS Financial Integrity of Transactions... A designated contract market that permits direct...implement appropriate financial risk limits. A designated contract market must implement and...

2014-04-01

391

17 CFR 38.607 - Direct access.  

Code of Federal Regulations, 2013 CFR

... DESIGNATED CONTRACT MARKETS Financial Integrity of Transactions... A designated contract market that permits direct...implement appropriate financial risk limits. A designated contract market must implement and...

2013-04-01

392

NASA directives master list and index  

NASA Technical Reports Server (NTRS)

This handbook sets forth in two parts, Master List of Management Directives and Index to NASA Management Directives, the following information for the guidance of users of the NASA Management Directives System. Chapter 1 contains introductory information material on how to use this handbook. Chapter 2 is a complete master list of agencywide management directives, describing each directive by type, number, effective date, expiration date, title, and organization code of the office responsible for the directive. 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 directives 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 Directives System are described in Chapter 8. The second part contains an in depth alphabetical index to all NASA management directives other than handbooks, most of which are indexed by titles only.

1995-01-01

393

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

394

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

395

Ionization based multi-directional flow sensor  

DOEpatents

A method, system, and apparatus for conducting real-time monitoring of flow (airflow for example) in a system (a hybrid power generation system for example) is disclosed. The method, system and apparatus measure at least flow direction and velocity with minimal pressure drop and fast response. The apparatus comprises an ion source and a multi-directional collection device proximate the ion source. The ion source is configured to generate charged species (electrons and ions for example). The multi-directional collection source is configured to determine the direction and velocity of the flow in real-time.

Chorpening, Benjamin T. (Morgantown, WV); Casleton, Kent H. (Morgantown, WV)

2009-04-28

396

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

397

Family physicians' attitudes toward advance directives.  

PubMed Central

OBJECTIVE: To examine the attitudes toward, the experience with and the knowledge of advance directives of family physicians in Ontario. DESIGN: Cross-sectional survey. PARTICIPANTS: A questionnaire was mailed to 1000 family physicians, representing a random sample of one-third of the active members of the Ontario College of Family Physicians; 643 (64%) responded. RESULTS: In all, 86% of the physicians favoured the use of advance directives, but only 19% had ever discussed them with more than 10 patients. Most of the physicians agreed with statements supporting the use of advance directives and disagreed with statements opposing their use. Of the respondents 80% reported that they had never used a directive in managing an incompetent patient. Of the physicians who responded that they had such experience, over half said that they had not always followed the directions contained in the directive. The proportions of physicians who responded that certain patient groups should be offered the opportunity to complete an advance directive were 96% for terminally ill patients, 95% for chronically ill patients, 85% for people with human immunodeficiency virus infection, 77% for people over 65 years of age, 43% for all adults, 40% for people admitted to hospital on an elective basis and 33% for people admitted on an emergency basis. The proportions of physicians who felt that the following strategies would encourage them to offer advance directives to their patients were 92% for public education, 90% for professional education, 89% for legislation protecting physicians against liability when following a directive, 80% for legislation supporting the use of directives, 79% for hospital policy supporting the use of directives, 73% for reimbursement for time spent discussing directives with patients and 64% for hospital policy requiring that all patients be routinely offered the opportunity to complete a directive at the time of admission. CONCLUSIONS: Family physicians favour advance directives but use them infrequently. Most physicians support offering them to terminally or chronically ill patients but not to all patients at the time of admission to hospital. Although governments emphasize legislation, most physicians believe that public and professional education programs would be at least as likely as legislation to encourage them to offer advance directives to their patients. PMID:1596842

Hughes, D L; Singer, P A

1992-01-01

398

Direct reading of electrocardiograms and respiration rates  

NASA Technical Reports Server (NTRS)

Technique for reading heart and respiration rates is more accurate and direct 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 directly from the appropriate scale.

Wise, J. P.

1969-01-01

399

Direct selective laser sintering of metals  

Microsoft Academic Search

Considers efforts to date to produce parts by direct selective laser sintering (SLS) of metals, including post processing to improve structural integrity and\\/or to induce a transformation. Provides a brief overview of the basic principles of SLS machine operation, and discusses materials issues affecting direct SLS of metals and the resultant properties and microstructures of the parts. Reviews results of

Mukesh Agarwala; David Bourell; Joseph Beaman; Harris Marcus; Joel Barlow

1995-01-01

400

Cease Remembering: Control Processes in Directed Forgetting  

Microsoft Academic Search

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 directed 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 directed forgetting effect, the magnitude

Kathleen L. Hourihan; Tracy L. Taylor

2006-01-01

401

From Expert Words Directly to Numerical Simulations  

E-print Network

From Expert Words Directly to Numerical Simulations: Group­Theoretic Approach to Computing to transform these expert words into numerical simulation (lead­ ing to prediction) is to use the fuzzy control, therefore, desirable to get from the original words directly to numerical simulations, thus avoiding this de

Kreinovich, Vladik

402

Direct amide formation using radiofrequency heating.  

PubMed

We present a simple method for direct and solvent-free formation of amides from carboxylic acids and amines using radiofrequency heating. The direct energy coupling of the AC magnetic field via nickel ferrite magnetic nanoparticles enables fast and controllable heating, as well as enabling facile work-up via magnetic separation. PMID:23175135

Houlding, Thomas K; Tchabanenko, Kirill; Rahman, Md Taifur; Rebrov, Evgeny V

2013-07-01

403

Well bore drilling direction changing method  

Microsoft Academic Search

This patent describes a method of changing the direction of drilling a well bore. It comprises: placing a slurry of hydraulic cement in water in the well bore at a location therein where the direction of drilling is to be changed and in an amount sufficient to form a plug therein; allowing the slurry to set into a rigid plug

K. L. Harris; C. Jr. Cook

1992-01-01

404

Hospital response to implementation of medical directives  

Microsoft Academic Search

This sandwich thesis presents the findings of a qualitative nested case study that explored the introduction of medical directives 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 directives in the hospital. In-depth, semi-structured interviews were conducted with a purposive sample

Kimberley Ann Alvarado

2007-01-01

405

On the Strong Direct Summand Conjecture  

ERIC Educational Resources Information Center

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 Direct Summand Conjecture, due to N. Ranganathan. Our results are separated into three chapters. In Chapter 3, we prove special cases of the Strong Direct Summand Conjecture in…

McCullough, Jason

2009-01-01

406

DIRECT INTERFACE TRACKING OF DROPLET DEFORMATION  

Microsoft Academic Search

Direct interface tracking computes spray behavior based only on first principles. It is an advanced form of direct numerical simulation, but with the emphasis shifted from resolving details of turbulence to details of multiphase flow. The moving interface requires special treatment and advanced numerical methods. A code that is capable of accurate resolution of three-dimensional free-surface deformation has been constructed.

David P. Schmidt; Meizhong Dai; Haoshu Wang; J. Blair Perot

2002-01-01

407

Catalysts for direct ethanol fuel cells  

Microsoft Academic Search

By comparing the performance of fuel cells operating on some low molecular weight alcohols, it resulted that ethanol may replace methanol in a direct alcohol fuel cell. To improve the performance of a direct ethanol fuel cell (DEFC), it is of great importance to develop anode catalysts for ethanol electro-oxidation more active than platinum alone. This paper presents an overview

Ermete Antolini

2007-01-01

408

SUMMER 2013 DIRECT PLUS LOAN FACT SHEET  

E-print Network

the student registers for summer classes. Your loan application will take approximately 7-10 business days, please go to www.pin.ed.gov and allow up to 10 business days to secure one. The PLUS loan cannot be usedSUMMER 2013 DIRECT PLUS LOAN FACT SHEET FOR UNDERGRADUATE STUDENTS A Federal Direct PLUS

409

SUMMER 2012 DIRECT PLUS LOAN FACT SHEET  

E-print Network

loan application will take approximately 7-10 business days to review. There are three separate steps to 10 business days to secure one. The PLUS loan cannot be used in the settlement of the student accountSUMMER 2012 DIRECT PLUS LOAN FACT SHEET FOR UNDERGRADUATE STUDENTS A Federal Direct PLUS

Spence, Harlan Ernest

410

SUMMER 2011 DIRECT PLUS LOAN FACT SHEET  

E-print Network

the student registers for summer classes. Your loan application will take approximately 7-10 business daysSUMMER 2011 DIRECT PLUS LOAN FACT SHEET FOR UNDERGRADUATE STUDENTS A Federal Direct PLUS is a federal credit-based loan which is available to assist parents with the costs of higher education

Spence, Harlan Ernest

411

SUMMER 2014 DIRECT PLUS LOAN FACT SHEET  

E-print Network

classes. Your loan application will take approximately 7-10 business days to review. There are threeSUMMER 2014 DIRECT PLUS LOAN FACT SHEET FOR UNDERGRADUATE STUDENTS A Federal Direct PLUS is a credit-based loan which is available to assist parents with the costs of higher education. The PLUS Loan

Spence, Harlan Ernest

412

SUMMER 2013 DIRECT PLUS LOAN FACT SHEET  

E-print Network

. The loan application will be reviewed in approximately 7-10 business days. The borrower must completeSUMMER 2013 DIRECT PLUS LOAN FACT SHEET FOR GRADUATE STUDENTS The Graduate Federal Direct PLUS is a federal credit-based loan, which is available to assist students with the costs of higher education

413

Independent Components Analysis by Direct Entropy Minimization  

E-print Network

) which can be simplified to a sum of one-dimensional marginal entropies (c.f. Kullback (1959Independent Components Analysis by Direct Entropy Minimization Erik G. Miller egmil) University of California Berkeley, California 94720 #12;Independent Components Analysis by Direct Entropy

Learned-Miller, Erik

414

Optimized aperiodic highly directional narrowband infrared emitters  

E-print Network

Optimized aperiodic highly directional narrowband infrared emitters Christopher H. Granier,1 as narrowband, highly directional thermal infrared emitters for both TE and TM polarizations. These aperiodic-infinite tungsten substrate exhibit extremely high emittance peaked around the wavelength at which the structures

Veronis, Georgios

415

Determining Directional Emittance With An Infrared Imager  

NASA Technical Reports Server (NTRS)

Directional 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. Directional 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.

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

1994-01-01

416

Stigma and Schizophrenia: Directions in Student Training  

ERIC Educational Resources Information Center

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 direct clinical work with clients in conjunction with field supervision and classroom education. Through direct practice in individual and group sessions, students learn…

Mason, Susan E.; Miller, Rachel

2006-01-01

417

Direct Instruction News: Effective School Practices, 2003.  

ERIC Educational Resources Information Center

The mission of the Association for Direct Instruction is to promote the improvement of effective educational methods. This journal, "Direct 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…

Tarver, Sara G., Ed.

2003-01-01

418

DBtk: A Toolkit for Directed Bigraphs  

NASA Astrophysics Data System (ADS)

We present DBtk, a toolkit for Directed Bigraphs. DBtk supports a textual language for directed bigraphs, the graphical visualization of bigraphs, the calculation of IPO labels, and the calculation of redex matchings. Therefore, this toolkit provides the main functions needed to implement simulators and verification tools.

Bacci, Giorgio; Grohmann, Davide; Miculan, Marino

419

New directions in UK energy policy  

Microsoft Academic Search

Purpose – The purpose of this short note is to briefly present the salient features of the new energy policy directions outlined in the recently published White Paper on energy policy by the UK Government. It also aims to present some critical thoughts on the new policy directions. Design\\/methodology\\/approach – The note is based on the author's review of the

Peter Cameron

2007-01-01

420

A Response to "New Direction for CCBD?"  

ERIC Educational Resources Information Center

The author is pleased to see that the future directions 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 directions, as appropriate. The authors of "New…

Colvin, Geoff

2011-01-01

421

Spectroscopy and Direct Products: Simpler yet Deeper  

ERIC Educational Resources Information Center

When irreducible representations are given in diagrammatic form, it is possible to show direct 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 direct product) can also be shown in pictorial form. The [upsilon](CO)…

Kettle, Sidney F. A.

2010-01-01

422

Focus Issue: Moving in the Right Direction  

NSDL National Science Digital Library

Cells interpret environmental cues to extend processes in the appropriate direction, descend upon sources of inflammation or necrosis, or determine the best path to the correct position in a developing organism. This Focus Issue of Science Signaling highlights the signaling pathways and mechanisms that enable cells to sense external signals and direct their movement accordingly.

Wei Wong (American Association for the Advancement of Science;Associate Editor of Science Signaling REV)

2011-04-26

423

Replicating Direction Service: A Hand Book.  

ERIC Educational Resources Information Center

The handbook details planning and development of a direction 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, Direction Service Center, is discussed for the following six areas: development of a resource…

Drake Univ., Des Moines, IA. Midwest Regional Resource Center.

424

Direct fired absorption machine flue gas recuperator  

DOEpatents

A recuperator which recovers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine. The recuperator includes a housing with liquid flowing therethrough, the liquid being in direct contact with the combustion gas for increasing the effectiveness of the heat transfer between the gas and the liquid.

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

1985-01-01

425

Determining Directions of Ultrasound in Solids  

NASA Technical Reports Server (NTRS)

Ultrasound shadows cast by grooves. Improved method for determining direction of ultrasound in materials is shadow method using Scanning laser acoustic microscopy (SLAM). Direction 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.

Generazio, Edward R.; Roth, Don J.

1987-01-01

426

NASA directives: Master list and index  

NASA Technical Reports Server (NTRS)

This Handbook sets forth in two parts the following information for the guidance of users of the NASA Management Directives System. Chapter 1 contains introductory information material on how to use this Handbook. Chapter 2 is a complete master list of Agency-wide management directives, describing each directive by type, number, effective date, expiration date, title, and organization code of the office responsible for the directive. 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 directives applicable to the Jet Propulsion Laboratory. Chapter 6 is a consolidated list of NASA management directives published in the code of Federal Regulations. Complementary manuals to the NASA Management Directives System are described in Chapter 7. Part B contains an in-depth alphabetical index to all NASA management directives other than Handbooks.

1994-01-01

427

Direct-to-Consumer Advertising of Pharmaceuticals  

PubMed Central

Since the FDA released new guidelines on broadcast direct-to-consumer advertising in 1997, the prevalence of direct-to-consumer advertising of prescription drugs has increased exponentially. The impact on providers, patients and the health care system is varied and dynamic, and the rapid changes in the last several years have markedly altered the health care landscape. To continue providing optimal medical care, physicians and other health-care providers must be able to manage this influence on their practice, and a more thorough understanding of this phenomenon is an integral step toward this goal. This review will summarize the history of direct-to-consumer drug advertisements and the current regulations governing them. It will summarize the evidence concerning the impact of direct-to-consumer advertising on the public, providers and the health care system and conclude with observations regarding the future of direct-to-consumer advertising. PMID:17524744

Gellad, Ziad F.; Lyles, Kenneth W.

2014-01-01

428

Direct oral anticoagulants: integration into clinical practice.  

PubMed

The introduction of direct oral anticoagulants (OACs) for the treatment and prevention of thromboembolic disease represents a shift from the traditional vitamin K antagonist-based therapies, which have been the mainstay of treatment for almost 60?years. A challenge for hospital formularies will be to manage the use of direct OACs from hospital to outpatient settings. Three direct OACs-apixaban, dabigatran and rivaroxaban-are widely approved across different indications, with rivaroxaban approved across the widest breadth of indications. A fourth direct OAC, edoxaban, has also completed phase III trials. Implementation of these agents by physicians will require an understanding of the efficacy and safety profile of these drugs, as well as an awareness of renal function, comedication use, patient adherence and compliance. Optimal implementation of direct OACs in the hospital setting will provide improved patient outcomes when compared with traditional anticoagulants and will simplify the treatment and prevention of thromboembolic diseases. PMID:25012514

Cowell, Richard P W

2014-09-01

429

DEVELOPMENT OF FUNCTIONAL NANOPARTICULATE MATERIALS: Examination of the Functional and Structural Properties of Nanoparticulate Metal Complexes Prepared by Precipitation with Compressed Antisolvent Technology  

E-print Network

#0;#26; cu#0;*c #0;#14;#0;,i #0;#14;#0;$ con c?i #0;#14;#0;#18;#0;.c th?nh #0;#14;#0;#25;t. C?c anh ch#0;% em c#0;0a t?i lu?n lu?n h#0;) tr#0;. nh#0;3ng quy#0;"t #0;#14;#0;%nh c#0;0a t?i. Tuy r#0; ng ?ng b?, c? d?, ch? b?c v? gia #0;#14;?nh b?n v...#0;. c? th#0;$ #0;#14;? kh?ng lu?n lu?n hi#0;$u r? nh#0;3ng quy#0;"t #0;#14;#0;%nh c#0;0a t?i, h#0;& lu?n h#0;) tr#0;. v? #0;#14;#0;*ng vi?n t?i ti#0;"n t#0;+i tr?n con #0;#14;#0;#18;#0;,ng h#0;&c v#0;#27;n, v? t?i hy v#0;&ng r#0; ng t?i #0;#14;? l...

Nguyen, Joseph G.

2008-01-01

430

Curvature coding is tuned for motion direction.  

PubMed

We have investigated the global and local motion tuning properties of curvature coding mechanisms using two shape after-effects believed to be mediated by curvature-sensitive mechanisms: the shape-frequency after-effect, or SFAE, and the shape-amplitude after-effect, or SAAE. The SFAE and SAAE are the phenomena in which adaptation to a sine-wave-shaped contour causes a shift in respectively the apparent shape-frequency and apparent shape-amplitude of a test contour in a direction away from that of the adapting stimulus. In the global motion condition the sinusoidal-shaped contours were made to drift within a fixed stimulus window in the direction of their axis of modulation. In the local motion condition the contour was constructed from a string of Gabors, and their carriers but not envelopes moved. We investigated selectivity to motion direction by using adaptor and test contours that moved either in the same or opposite directions. We found that in the global motion condition both the SFAE and SAAE showed selectivity to motion direction, and that for the same-motion-direction condition, both after-effects increased with shape temporal frequency. We then examined the effect of luminance spatial frequency and luminance temporal frequency on global motion direction selectivity. Luminance temporal frequency accounted for some of the increase in after-effect magnitude with shape temporal frequency, but shape temporal frequency also contributed. The local motion after-effects on the other hand were neither selective to motion direction nor increased with luminance temporal frequency. Taken together, the results are best understood by supposing that curvature is encoded by mechanisms that are selective to motion direction and that the directional selectivity best manifests itself psychophysically when there is sufficient spatio-temporal coverage of the stimulus to stimulate the full array of potentially responsive curvature-coding mechanisms. PMID:20377295

Gheorghiu, Elena; Kingdom, Frederick; Varshney, Rickul

2010-01-01

431

Weld repair of directionally solidified articles  

NASA Technical Reports Server (NTRS)

A directionally solidified nickel-base superalloy article has a defect therein extending parallel to the solidification direction. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the directionally solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a direction parallel to the solidification direction. Optionally, additional artificial heat extraction is accomplished in a heat-flow direction that is within about 45 degrees of the solidification direction, as the filler metal solidifies within the defect. The article may thereafter be heat treated.

Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)

2002-01-01

432

Directionally solidified article with weld repair  

NASA Technical Reports Server (NTRS)

A directionally solidified nickel-base superalloy article has a defect therein extending parallel to the solidification direction. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the directionally solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a direction parallel to the solidification direction. Optionally, additional artificial heat extraction is accomplished in a heat-flow direction that is within about 45 degrees of the solidification direction, as the filler metal solidifies within the defect. The article may thereafter be heat treated.

Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)

2003-01-01

433

Stimulus Dependence of Barrel Cortex Directional Selectivity  

PubMed Central

Neurons throughout the rat vibrissa somatosensory pathway are sensitive to the angular direction of whisker movement. Could this sensitivity help rats discriminate stimuli? Here we use a simple computational model of cortical neurons to analyze the robustness of directional selectivity. In the model, directional preference emerges from tuning of synaptic conductance amplitude and latency, as in recent experimental findings. We find that directional selectivity during stimulation with random deflection sequences is strongly dependent on the mean deflection frequency: Selectivity is weakened at high frequencies even when each individual deflection evokes strong directional tuning. This variability of directional selectivity is due to generic properties of synaptic integration by the neuronal membrane, and is therefore likely to hold under very general physiological conditions. Our results suggest that directional selectivity depends on stimulus context. It may participate in tasks involving brief whisker contact, such as detection of object position, but is likely to be weakened in tasks involving sustained whisker exploration (e.g., texture discrimination). PMID:17205141

Puccini, Gabriel D.; Compte, Albert; Maravall, Miguel

2006-01-01

434

Implied body action directs spatial attention.  

PubMed

Research confirms that the body influences perception, but little is known about the embodiment of attention. We investigated whether the implied actions of others direct spatial attention, using a lateralized covert-orienting task with nonpredictive central cues depicting static, right/left-facing bodies poised in midaction. Validity effects (decreased response times for validly compared with invalidly cued trials) indicated orienting in the direction of the implied action. In Experiment 1, we compared action (running, throwing) with nonaction (standing) cues. Only the action cues produced validity effects, suggesting that implied action directs attention. The action cues produced faster responses overall, suggesting that action cues prime motor responses. In Experiment 2, we determined whether action cues shifted attention in a specific direction rather than to a general side of space: Two cues had similar action speed and motor effort but differed in implied direction (jumping, vertical; throwing, horizontal). Validity effects were found only for the throw cues for which the implied motion direction was consistent with lateralized target locations. In Experiment 3, we compared block-like stimuli to the throwing action stimuli to examine whether lower level perceptual information could account for the attention effects alone. Validity effects were found only for the human-action stimuli. Overall, the results suggest that predictive simulations of action shift attention in action-consistent directions. PMID:20675790

Gervais, Will M; Reed, Catherine L; Beall, Paula M; Roberts, Ralph J

2010-08-01

435

Stiff directed lines in random media  

NASA Astrophysics Data System (ADS)

We investigate the localization of stiff directed lines with bending energy by a short-range random potential. We apply perturbative arguments, Flory scaling arguments, a variational replica calculation, and functional renormalization to show that a stiff directed line in 1+d dimensions undergoes a localization transition with increasing disorder for d>2/3. We demonstrate that this transition is accessible by numerical transfer matrix calculations in 1+1 dimensions and analyze the properties of the disorder-dominated phase in detail. On the basis of the two-replica problem, we propose a relation between the localization of stiff directed lines in 1+d dimensions and of directed lines under tension in 1+3d dimensions, which is strongly supported by identical free-energy distributions. This shows that pair interactions in the replicated Hamiltonian determine the nature of directed line localization transitions with consequences for the critical behavior of the Kardar-Parisi-Zhang equation. We support the proposed relation to directed lines via multifractal analysis, revealing an analogous Anderson transition-like scenario and a matching correlation length exponent. Furthermore, we quantify how the persistence length of the stiff directed line is reduced by disorder.

Boltz, Horst-Holger; Kierfeld, Jan

2013-07-01

436

Contrasting the direct radiative effect and direct radiative forcing of aerosols  

E-print Network

The direct radiative effect (DRE) of aerosols, which is the instantaneous radiative impact of all atmospheric particles on the Earth's energy balance, is sometimes confused with the direct radiative forcing (DRF), which ...

Heald, Colette L.

437

Seaweed to Dendrite Transition in Directional Solidification  

NASA Astrophysics Data System (ADS)

We simulate directional solidification using a phase-field model solved with adaptive mesh refinement. For small surface tension anisotropy directed at 45° relative to the pulling direction we observe a crossover from a seaweed to a dendritic morphology as the thermal gradient is lowered, consistent with recent experimental findings. We show that the morphology of crystal structures can be unambiguously characterized through the local interface velocity distribution. We derive semiempirically an estimate for the crossover from seaweed to dendrite as a function of thermal gradient and pulling speed.

Provatas, Nikolas; Wang, Quanyong; Haataja, Mikko; Grant, Martin

2003-10-01

438

Seaweed to Dendrite Transition in Directional Solidification  

NASA Astrophysics Data System (ADS)

We simulate directional solidification using a phase-field model solved with adaptive mesh refinement. For small surface tension anisotropy directed at 45 degree relative to the pulling direction we observe a corssover from a seaweed to a dendritic morphology as the thermal gradient is lowered, consistent with recent experimental findings. We show that the morphology of crystal structures can be unambiguously characterized through the local interface velocity distribution. We derive semiempirically an estimate for the crossover from seaweed to dendrite as a function of thermal gradient and pulling speed.

Wang, Quanyong; Provatas, Nikolas; Haataja, Mikko; Grant, Martin

2004-03-01

439

Directed embryo donation: free choice or discrimination?  

PubMed

The issue of whether to allow or prohibit the directed anonymous donation of human embryos for reproductive use has been publicly contentious. The claims that directed donation are a donor's autonomous right contrast with claims that the practice is discriminatory. Recent legislation and legal recommendation on the issue has been inconsistent or contradictory. This article specifically addresses the question as to whether the directed donation of embryos is the exercise of free choice or an act of discrimination. This question is considered from both ethical and legal viewpoints. PMID:20977170

de Lacey, Sheryl; Rogers, Wendy; Richards, Bernadette

2010-09-01

440

Directional excitation of graphene surface plasmons  

E-print Network

We propose a scheme to directionally couple light into graphene plasmons by placing a graphene sheet on a magneto-optical substrate. When a magnetic field is applied parallel to the surface, the graphene plasmon dispersion relation becomes asymmetric in the forward and backward directions. It is possible to achieve unidirectional excitation of graphene plasmons with normally incident illumination by applying a grating to the substrate. The directionality can be actively controlled by electrically gating the graphene, or by varying the magnetic bias. This scheme may have applications in graphene-based opto-electronics and sensing.

Liu, Fangli; Chong, Y D

2014-01-01

441

Direct solar steam-generating system  

NASA Astrophysics Data System (ADS)

A new technology that generates steam by the use of solar energy is described. Steam is generated directly in the solar collectors. The advantages of direct solar steam generation are compared with the methods of indirect solar steam generation. Schematics and modes of operation of a demonstration system are presented. Feasibility of the concept, and how to obtain necessary design parameters, was established. The feasibility of direct solar steam generation is shown. This concept is suitable for generating low pressure steam. The major applications are expected to be in process steam, absorption cooling, and steam heating.

Vresk, J.

442

Directional drilling used in Mississippi River crossing  

SciTech Connect

Tennessee Gas Pipeline Co. recently completed its longest large-diameter directional bore and pulled nearly 3,000 feet of 20-in. replacement pipe under the Southwest Pass of the Mississippi River. The replacement was necessary to allow for planned widening and deepening of Southwest Pass. This article explains why conventional dredging methods were not possible. It then explains how the directional drilling was done. Given favorable soil conditions such as found along much of the Gulf Coast, the speed of installation, environmental consideration of dredging eliminated, and the cost-competitive posture Tennessee found among the directional drilling contractors, Tennessee plans to utilize this technique increasingly in the future.

Fuess, G.T.

1988-05-02

443

Outrunning Nature: Directed Evolution of Superior Biocatalysts  

NASA Astrophysics Data System (ADS)

Driven by recent technical advances in genetic engineering and new societal needs, the use of enzymes and microorganisms as catalysts to synthesize chemicals and materials is rapidly expanding. One of the key technical drivers is the development of various directed evolution methods for biocatalyst discovery and optimization. Although it essentially replicates the Darwinian evolutionary processes in a test tube, directed evolution can create biocatalysts with better catalytic performance than Nature's own products within weeks or months rather than eons. In this article, both the technologies and applications of directed evolution in biocatalysis are discussed.

Woodyer, Ryan; Chen, Wilfred; Zhao, Huimin

2004-01-01

444

SciVerse ScienceDirect SciVerse ScienceDirect iPhone app  

E-print Network

SciVerse ScienceDirect SciVerse ScienceDirect iPhone app User Guide December 2010 Open;Welcome to the SciVerse ScienceDirect iPhone app: How to use this step-by-step guide The SciVerse ScienceDirect iPhone app connects users to a leading full-text scientific database offering journal articles

Twente, Universiteit

445

Records Management Vice-Chancellor's Directive 1 Records Management Vice-Chancellor's Directive  

E-print Network

Records Management Vice-Chancellor's Directive 1 Records Management Vice-Chancellor's Directive-Chancellor's Directive Privacy Management Plan Intellectual Property Policy UTS Records Management Procedures Privacy Access) Act 2009 (NSW) (GIPA Act) File number UR07/1205 Superseded documents Records Management Vice

University of Technology, Sydney

446

A direct search for Dirac magnetic monopoles  

E-print Network

Magnetic monopoles are highly ionizing and curve in the direction of the magnetic field. A new dedicated magnetic monopole trigger at CDF, which requires large light pulses in the scintillators of the time-of-flight system, ...

Mulhearn, Michael James

2005-01-01

447

49 CFR 192.490 - Direct assessment.  

Code of Federal Regulations, 2011 CFR

...FEDERAL SAFETY STANDARDS Requirements for Corrosion Control § 192.490 Direct assessment...process. Threat Standard 1 External corrosion § 192.925 2 Internal corrosion in pipelines that transport dry gas §...

2011-10-01

448

49 CFR 192.490 - Direct assessment.  

Code of Federal Regulations, 2012 CFR

...FEDERAL SAFETY STANDARDS Requirements for Corrosion Control § 192.490 Direct assessment...process. Threat Standard 1 External corrosion § 192.925 2 Internal corrosion in pipelines that transport dry gas §...

2012-10-01

449

49 CFR 192.490 - Direct assessment.  

Code of Federal Regulations, 2010 CFR

...FEDERAL SAFETY STANDARDS Requirements for Corrosion Control § 192.490 Direct assessment...process. Threat Standard 1 External corrosion § 192.925 2 Internal corrosion in pipelines that transport dry gas §...

2010-10-01

450

Fabric of Kaolinite in Direct Shear Tests.  

National Technical Information Service (NTIS)

Fabric data on kaolinite samples sheared in drained direct shear are obtained from carbowax impregnated samples that were examined by light microscopy and x-ray diffraction. Previous research in this laboratory has repeatedly demonstrated that when proper...

R. T. Martin

1972-01-01

451

From Subscription Agency to Direct Publisher Service  

Microsoft Academic Search

Subscription agency fees for journals and handling charges increase each year. GAF Chemicals Corporation Library was faced with the decision to cancel agency services at management's request. This paper presents the successful alternative of direct publisher's service.

Melanie C. Sze; Ira Naznitsky

1991-01-01

452

Relationships between direct predation and risk effects.  

PubMed

Risk effects arise when prey alter their behavior in response to predators, and these responses carry costs. Empirical studies have found that risk effects can be large. Nonetheless, studies of predation in vertebrate conservation and management usually consider only direct predation. Given the ubiquity and strength of behavioral responses to predators by vertebrate prey, it is not safe to assume that risk effects on dynamics can be ignored. Risk effects can be larger than direct effects. Risk effects can exist even when the direct rate of predation is zero. Risk effects and direct effects do not necessarily change in parallel. When risk effects reduce reproduction rather than survival, they are easily mistaken for limitation by food supply. PMID:18308423

Creel, Scott; Christianson, David

2008-04-01

453

Spatially Refined Aerosol Direct Radiative Forcing Efficiencies  

EPA Science Inventory

Global aerosol direct radiative forcing (DRF) is an important metric for assessing potential climate impacts of future emissions changes. However, the radiative consequences of emissions perturbations are not readily quantified nor well understood at the level of detail necessary...

454

Direct computation of the sensible heat flux.  

USGS Publications Warehouse

An algorithm to determine the sensible heat flux from simple field measurements (wind speed, air and ground temperatures) has been developed. It provides a direct solution, in parametric form, which can be displayed graphically or tabularly. -from Author

Watson, K.

1980-01-01

455

Three Magnetic Direct-Current Sensors  

NASA Technical Reports Server (NTRS)

Three direct-current-measuring circuits based on magnetic (transformer) coupling, with periodic reset of magnetic flux to reverse saturation. Unidirectional and bidirectional versions demonstrated. Offers greater realibility and lower power consumption.

Sullender, Craig C.; Stagg, David A.

1994-01-01

456

Dark Matter -- Possible Candidates and Direct Detection  

E-print Network

The cosmological observations coupled with theoretical calculations suggest the existence of enormous amount of unseen and unknown matter or dark matter in the universe. The evidence of their existence, the possible candidates and their possible direct detections are discussed.

Debasish Majumdar

2007-03-29

457

78 FR 47537 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration...Airbus Model A330-200 and -300 series airplanes, and Model A340-200 and -300 series airplanes. AD 2005-07-04 required...

2013-08-06

458

78 FR 28152 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration (FAA...to certain Airbus Model A318-111 and -112 airplanes, Model A319 series airplanes, Model A320 series airplanes, and Model...

2013-05-14

459

78 FR 9341 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration...A318, A319, A320, and A321 series airplanes. The existing AD currently requires...control unit (BSCU) standard and adds airplanes to [[Page 9342

2013-02-08

460

78 FR 78694 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration...Airbus Model A330-200 and -300 series airplanes, and Model A340-200 and -300 series airplanes. AD 2009-24-09 required a...

2013-12-27

461

78 FR 78705 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration (FAA...2010-24-07 for all Airbus Model A318 series airplanes, Model A319 series airplanes, Model A320 series airplanes, and Model...

2013-12-27

462

77 FR 68711 - Airworthiness Directives; Airbus Airplanes  

Federal Register 2010, 2011, 2012, 2013

...2120-AA64 Airworthiness Directives; Airbus Airplanes AGENCY: Federal Aviation Administration...Airbus Model A330-200 and -300 series airplanes; and Model A340-200, -300, -500, and -600 series airplanes. The existing AD currently...

2012-11-16

463

Developing Science Process Skills through Directed Inquiry.  

ERIC Educational Resources Information Center

The Directed Inquiry Approach to Learning Science Process Skills and Scientific Problem Solving [DIAL(SPS)2] is described. Concept mapping, advance organizers, Vee diagrams, the theme approach, and focusing are used to help students develop science process skills. (KR)

Germann, Paul J.

1991-01-01

464

Social interaction in advertising directed to children  

Microsoft Academic Search

This study investigated the efficacy of including peer interaction in television advertising directed to children. Results suggest that this variable provides increased liking for commercials, but does not affect product desirability.

Meagan Loughlin; Roger Jon Desmond

1981-01-01

465

Online Advertising and Marketing Directed Toward Children  

Microsoft Academic Search

OECD Committee on Consumer Policy Forum Session on Online Advertising and Marketing Directed toward Children, intended to provide information on how OECD Member countries are dealing with issues related to children and the Internet.

1999-01-01

466

Comparison of direct and rejection sampling methods  

SciTech Connect

In this paper, the authors compare direct sampling methods with rejection sampling for some common probability density functions (pdf's) used in Monte Carlo codes. Timing results obtained on several types of engineering workstation indicate that the direct sampling methods are always competitive with and usually faster than rejection schemes. Direct methods also involve coding that is easier to understand and debug, hence is less prone to errors. For these reasons, it is recommended that direct methods be used in most new Monte Carlo work. Monte Carlo codes used for particle transport analysis generally involve three different categories of random sampling. The authors here investigate one of these - random sampling from well-known pdf's, such as the normal and exponential densities, as part of the physics analysis.

Brown, F.B. (Argonne National Lab., IL (United States)); Vujic, J. (Univ. of California, Berkeley, CA (United States))

1993-01-01

467

49 CFR 192.490 - Direct assessment.  

Code of Federal Regulations, 2013 CFR

...FEDERAL SAFETY STANDARDS Requirements for Corrosion Control § 192.490 Direct assessment...process. Threat Standard 1 External corrosion § 192.925 2 Internal corrosion in pipelines that transport dry gas §...

2013-10-01

468

Our Purpose and Direction Forestry Commission Wales  

E-print Network

. Woodland creation and wider use of timber for both construction and for fuel locks up carbon and helps beyond the 50-year lifespan of Woodlands for Wales. Our Purpose and Direction John Griffiths AM Minister

469

Direct Foreign Investment in the United Kingdom.  

ERIC Educational Resources Information Center

Notes introductory undergraduate economics textbooks have no formal analysis of the rationale for direct foreign investment by multinational firms. Examines this area in an attempt to develop more content information for undergraduate courses. (RKM)

Hinde, Kevin

1987-01-01

470

SMITHSONIAN DIRECTIVE 604 September 8, 2006  

E-print Network

improprieties, animal use and care regulations, or criminal matters. Definitions Research MisconductSMITHSONIAN DIRECTIVE 604 September 8, 2006 MISCONDUCT IN RESEARCH Purpose 1 Applicability 2 Institution fosters a research environment that promotes the responsible conduct of research, discourages

Weston, Ken

471

CELL BIOLOGY: Two Lipids That Give Direction  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Precise and sequential intracellular signaling events involving two phospholipids direct an immune cell toward an attractant molecule gradient.

Jean-François Côté (Université de Montréal;Institut de Recherches Cliniques de Montréal); Kristiina Vuori (Burnham Institute for Medical Research;)

2009-04-17

472

Move-In Directions Douglass Campus  

E-print Network

and name of assigned building. · Write your room number and cell phone number on the sheet with your number. Please follow these specific driving directions, avoiding alternate routes. They will allow#___________________ PHONE#_____________________________________________ #12;

473

Direct transfer of graphene onto flexible substrates  

E-print Network

In this paper we explore the direct transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. The transfer method investigated here is fast, simple, and does not require an intermediate ...

Araujo, P. T.

474

A Modified Direct-Reading Azimuth Protractor  

ERIC Educational Resources Information Center

Describes the construction of a direct-reading azimuth protractor (DRAP) used for mapping fracture and joint-surface orientations in underground mines where magnetic disturbances affect typical geologic pocket transit. (SL)

Larson, William C.; Pugliese, Joseph M.

1977-01-01

475

Air Breathing Direct Methanol Fuel Cell  

DOEpatents

A method for activating a membrane electrode assembly for a direct methanol fuel cell is disclosed. The method comprises operating the fuel cell with humidified hydrogen as the fuel followed by running the fuel cell with methanol as the fuel.

Ren; Xiaoming (Los Alamos, NM)

2003-07-22

476

Unstructured Direct Elicitation of Decision Rules  

E-print Network

We investigate the feasibility of unstructured direct-elicitation (UDE) of decision rules consumers use to form consideration sets. With incentives to think hard and answer truthfully, tested formats ask respondents to ...

Ding, Min

477