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Sample records for qualite applicable au

  1. Qualitative biomechanical principles for application in coaching.

    PubMed

    Knudson, Duane

    2007-01-01

    Many aspects of human movements in sport can be readily understood by Newtonian rigid-body mechanics. Many of these laws and biomechanical principles, however, are counterintuitive to a lot of people. There are also several problems in the application of biomechanics to sports, so the application of biomechanics in the qualitative analysis of sport skills by many coaches has been limited. Biomechanics scholars have long been interested in developing principles that facilitate the qualitative application of biomechanics to improve movement performance and reduce the risk of injury. This paper summarizes the major North American efforts to establish a set of general biomechanical principles of movement, and illustrates how principles can be used to improve the application of biomechanics in the qualitative analysis of sport technique. A coach helping a player with a tennis serve is presented as an example. The standardization of terminology for biomechanical principles is proposed as an important first step in improving the application ofbiomechanics in sport. There is also a need for international cooperation and research on the effectiveness of applying biomechanical principles in the coaching of sport techniques. PMID:17542182

  2. Qualitative Research Applications in Athletic Training

    PubMed Central

    Pitney, William A.; Parker, Jenny

    2002-01-01

    Objective: To explain the ethnographic, phenomenologic, and grounded theory approaches to qualitative research and to describe how these approaches can be applied to contemporary topics related to athletic training education. Background: Athletic training education has recently experienced an increase in the use of qualitative methods, and various qualitative approaches are viable for answering many questions related to athletic training education. Ethnography focuses on describing a culture or subculture. Phenomenology focuses on the meaning of lived human experience. Grounded theory focuses on developing theory related to social processes. Each approach is contextual and attempts to facilitate insight and understanding related to the human condition. Description: We provide an in-depth discussion of each of the selected qualitative approaches and explain the focus and unique data-collection and data-analysis strategies and identify the distinctive outcomes of each approach. Each research approach has a distinct purpose, and the specific application is driven by the questions asked. We also identify questions that are amenable to a specific method. Applications: To better understand the interactive nature of education and learning, athletic training researchers are beginning to ask questions that require information to be gathered about meaning, contexts, culture, and processes. Such questions are best answered through the use of qualitative research methods that most commonly include ethnography, phenomenology, and grounded theory. In order for athletic training professionals to gain the most from the research conducted, it is essential that they have an understanding of the theoretic underpinnings of these methods and when each should be used. PMID:12937540

  3. Validity in Qualitative Research: Application of Safeguards

    ERIC Educational Resources Information Center

    Daytner, Katrina M.

    2006-01-01

    The construct of validity has received considerable attention in qualitative methods literature (Denzin, 1989; Erickson, 1986; Geertz, 1973; Goetz & LeCompte, 1984; Howe & Eisenhart, 1990; Maxwell, 1992; Smith & Glass, 1987). Much of the attention has been focused upon the issue of whether qualitative results and interpretations accurately reflect…

  4. Qualitative Reasoning for Additional Die Casting Applications

    SciTech Connect

    R. Allen Miller; Dehua Cui; Yuming Ma

    2003-05-28

    If manufacturing incompatibility of a product can be evaluated at the early product design stage, the designers can modify their design to reduce the effect of potential manufacturing problems. This will result in fewer manufacturing problems, less redsign, less expensive tooling, lower cost, better quality, and shorter development time. For a given design, geometric reasoning can predict qualitatively the behaviors of a physical manufacturing process by representing and reasoning with incomplete knowledge of the physical phenomena. It integrates a design with manufacturing processes to help designers simultaneously consider design goals and manufacturing constraints during the early design stage. The geometric reasoning approach can encourage design engineers to qualitatively evaluate the compatibility of their design with manufacturing limitations and requirements.

  5. Fe/Au Core-Shell Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Sra, Amandeep; Leslie-Pelecky, Diandra

    2009-10-01

    The physical properties of nanoparticles, including size, composition and surface chemistry, greatly influence biological and pharmacological properties and, ultimately, their clinical applications. Superparamagnetic iron oxide nanoparticles are widely used for applications such as MRI contrast agents, drug delivery via magnetic targeting and hyperthermia due to their chemical stability and biocompatibility; however, enhancing the saturation magnetization (Ms) of nanoparticles would produce greater sensitivity. Our design strategy involves a bottom-up wet chemistry approach to the synthesis of Fe nanoparticles. Specific advantages of Fe are the high value of Ms (210 emu/g in bulk) coupled with low toxicity; however, Fe nanoparticles must be protected from oxidation, which causes a dramatic reduction in Ms. To circumvent oxidation, Fe nanoparticles are coated with a Au shell that prevents the oxidation of the magnetic core and also provides the nanoparticles with plasmonic properties for optical stimulation. Ligands of various functionalities can be introduced through the well established Au-thiol surface chemistry for different biomedical applications while maintaining the magnetic functionality of the Fe core. In this presentation, we will discuss the physical, chemical and magnetic properties of our Fe/Au nanoparticles and their resistance to oxidation.

  6. Bright, NIR-emitting Au23 from Au25: characterization and applications including biolabeling.

    PubMed

    Muhammed, Madathumpady Abubaker Habeeb; Verma, Pramod Kumar; Pal, Samir Kumar; Kumar, R C Arun; Paul, Soumya; Omkumar, Ramakrishnapillai Vyomakesannair; Pradeep, Thalappil

    2009-10-01

    A novel interfacial route has been developed for the synthesis of a bright-red-emitting new subnanocluster, Au(23), by the core etching of a widely explored and more stable cluster, Au(25)SG(18) (in which SG is glutathione thiolate). A slight modification of this procedure results in the formation of two other known subnanoclusters, Au(22) and Au(33). Whereas Au(22) and Au(23) are water soluble and brightly fluorescent with quantum yields of 2.5 and 1.3 %, respectively, Au(33) is organic soluble and less fluorescent, with a quantum yield of 0.1 %. Au(23) exhibits quenching of fluorescence selectively in the presence of Cu(2+) ions and it can therefore be used as a metal-ion sensor. Aqueous- to organic-phase transfer of Au(23) has been carried out with fluorescence enhancement. Solvent dependency on the fluorescence of Au(23) before and after phase transfer has been studied extensively and the quantum yield of the cluster varies with the solvent used. The temperature response of Au(23) emission has been demonstrated. The inherent fluorescence of Au(23) was used for imaging human hepatoma cells by employing the avidin-biotin interaction. PMID:19711391

  7. Shape-controlled synthesis of Au-Pd bimetallic nanocrystals for catalytic applications.

    PubMed

    Zhang, Lei; Xie, Zhaoxiong; Gong, Jinlong

    2016-07-21

    Au-Pd nanostructured materials have been recognized as important heterogeneous catalysts in various reactions, due to their superior activities caused by the ensemble and ligand effects. In recent years, shape-controlled synthesis of noble metal nanocrystals (NCs) provided a brand-new insight for improving the performance of catalysts. The electronic properties and catalytic activities of Au-Pd NCs could be optimized by tuning their shape and composition engineering. This review describes recent progress in the design and synthesis of shape-controlled Au-Pd bimetallic NCs and their emerging catalytic applications. The review starts with a general discussion of various applications of Au-Pd catalysts and the significance of preparing shape-controlled Au-Pd NCs, followed by an overview of synthetic strategies for two different structures of Au-Pd bimetallic catalysts: a core-shell structure and an alloy structure. We also put forward the key factors for the preparation of Au-Pd core-shell and alloy structures. Additionally, we discussed the unique optical properties and structural effects of shape-controlled Au-Pd NCs. These recent advancements in the methodology development of Au-Pd bimetallic NCs offer numerous insights for generating Au-Pd NCs with a number of unique geometries in the future. Furthermore, the systematic synthesis of core-shell or alloy structures would provide insights for the preparation of other bimetallic NCs. PMID:27095006

  8. The characteristics of Au:VO2 nanocomposite thin film for photo-electricity applications

    NASA Astrophysics Data System (ADS)

    Zhu, Yabin; Na, Jie; He, Fan; Zhou, Yueliang

    2013-08-01

    Au nanoparticles have been fabricated on normal glass substrates using nanosphere lithography (NSL) method. Vanadium dioxide has been deposited on Au/glass by reactive radio frequency (rf) magnetron sputtering. The structure and composition were determined by X-ray diffraction and X-ray photoelectron spectroscope. Electrical and optical properties of bare VO2 and Au:VO2 nanocomposite thin films were measured. Typical hysteresis behavior and sharp phase transition were observed. Nanopartical Au could effectively reduce the transition temperature to 40 °C. The transmittance spectrum for both Au:VO2 nanocomposite thin film shows high transmittance under transition temperature and low transmittance above transition temperature. The characteristics present the Au:VO2 nanocomposite thin film can be used for applications, such as “smart window” or “laser protector”.

  9. Thermal stability of Mo/Au bilayers for TES applications

    NASA Astrophysics Data System (ADS)

    Parra-Borderías, María; Fernández-Martínez, Iván; Fàbrega, Lourdes; Camón, Agustín; Gil, Oscar; González-Arrabal, Raquel; Sesé, Javier; Costa-Krämer, José Luis; Warot-Fonrose, Bénédicte; Serin, Virginie; Briones, Fernando

    2012-09-01

    Mo/Au bilayers are among the most suitable materials to be used as transition-edge sensors (TES) in cryogenic microcalorimeters and bolometers, developed, among other fields, for space missions. For this purpose the thermal stability of TES at temperatures below 150 °C is a critical issue. We report on the dependence of functional properties (superconducting critical temperature, residual resistance and α) as well as on microstructure, chemical composition and interface quality for optimized high quality Mo/Au bilayers on annealing temperature and time. Data show that the functional properties of the bilayers remain stable at T < 150 °C, but changes in microstructure, interface quality and functional properties were observed for layers heated at T ≥ 200 °C. Microstructural and chemical composition data suggest that the measured changes in residual resistance ratio (RRR) and TC at T ≥ 200 °C are mainly due to an increase in the average Au grain size and to Au migration along the Mo grain boundaries at the Au/Mo interface. A way to stabilize the functional properties of the Mo/Au bilayers against temperature enhancements is proposed.

  10. Application of statistical process control to qualitative molecular diagnostic assays.

    PubMed

    O'Brien, Cathal P; Finn, Stephen P

    2014-01-01

    Modern pathology laboratories and in particular high throughput laboratories such as clinical chemistry have developed a reliable system for statistical process control (SPC). Such a system is absent from the majority of molecular laboratories and where present is confined to quantitative assays. As the inability to apply SPC to an assay is an obvious disadvantage this study aimed to solve this problem by using a frequency estimate coupled with a confidence interval calculation to detect deviations from an expected mutation frequency. The results of this study demonstrate the strengths and weaknesses of this approach and highlight minimum sample number requirements. Notably, assays with low mutation frequencies and detection of small deviations from an expected value require greater sample numbers to mitigate a protracted time to detection. Modeled laboratory data was also used to highlight how this approach might be applied in a routine molecular laboratory. This article is the first to describe the application of SPC to qualitative laboratory data. PMID:25988159

  11. Effect of Au nanorods on potential barrier modulation in morphologically controlled Au@Cu2O core-shell nanoreactors for gas sensor applications.

    PubMed

    Majhi, Sanjit Manohar; Rai, Prabhakar; Raj, Sudarsan; Chon, Bum-Soo; Park, Kyung-Kuen; Yu, Yeon-Tae

    2014-05-28

    In this work, Au@Cu2O core-shell nanoparticles (NPs) were synthesized by simple solution route and applied for CO sensing applications. Au@Cu2O core-shell NPs were formed by the deposition of 30-60 nm Cu2O shell layer on Au nanorods (NRs) having 10-15 nm width and 40-60 nm length. The morphology of Au@Cu2O core-shell NPs was tuned from brick to spherical shape by tuning the pH of the solution. In the absence of Au NRs, cubelike Cu2O NPs having ∼200 nm diameters were formed. The sensor having Au@Cu2O core-shell layer exhibited higher CO sensitivity compared to bare Cu2O NPs layer. Tuning of morphology of Au@Cu2O core-shell NPs from brick to spherical shape significantly lowered the air resistance. Transition from p- to n-type response was observed for all devices below 150 °C. It was demonstrated that performance of sensor depends not only on the electronic sensitization of Au NRs but also on the morphology of the Au@Cu2O core-shell NPs. PMID:24779525

  12. Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection.

    PubMed

    Zhang, Hongfang; Liu, Ruixiao; Sheng, Qinglin; Zheng, Jianbin

    2011-02-01

    This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H(2)O(2) in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010-0.12mM with a detection limit of 4μM. This provided a method to the determination of glucose. PMID:21115279

  13. Highly selective ratiometric fluorescent probe for Au3+ and its application to bioimaging.

    PubMed

    Choi, Ji Young; Kim, Gun-Hee; Guo, Zhiqian; Lee, Hye Yeon; Swamy, K M K; Pai, Jaeyoung; Shin, Seunghoon; Shin, Injae; Yoon, Juyoung

    2013-11-15

    The 4-propargylamino-1,8-naphthalimide based fluorescent probe 1 has been explored as a sensor for selective detection of Au(3+). 4-Amino-1,8-naphthalimides, that possess typical intramolecular charge transfer (ICT) electronic characteristics, have been widely used as versatile platforms for fluorescent probes. The newly designed probe 1 contains a propargylamine moiety at C-4 of the naphthalimide chromophore that reacts with Au(3+) to generate a product that has distinctly different electronic properties from 1. Specifically, the probe undergoes a remarkable change in its absorption spectrum upon addition of Au(3+) that is associated with a distinct color change from yellow to light pink. In addition, a blue shift of ca. 56 nm also takes place in the emission spectra of the probe. Consequently, 1 serves as a reaction-based sensor or so called chemodosimeter for Au(3+). Importantly, surfactants enhance the rate of reaction of 1 with Au(3+), thus, enhancing its use as a real time sensor. Finally, the results of studies probing its application to bioimaging of Au(3+) in live cells show that the probe 1 has a unique ability to sense Au(3+) in cells and, in particular, in lipid droplets within cells. PMID:23810913

  14. Synthesis and biosensor application of Ag@Au bimetallic nanoparticles based on localized surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Ghodselahi, T.; Arsalani, S.; Neishaboorynejad, T.

    2014-05-01

    This work demonstrates a simple method for synthesizing gold-silver bimetallic nanoparticles (Ag@Au BNPs). Ag@Au BNPs on the carbon thin film are prepared by co-deposition of RF-sputtering and RF-PECVD using acetylene gas and gold-silver target. X-ray diffraction analysis indicates that Au and Ag NPs with FCC crystal structure are formed in our samples. From AFM image and data, average particles size of gold and silver are estimated to be about 5 and 8 nm, respectively. XRD profile and localized surface plasmon resonance (LSPR) spectroscopy indicate that Ag NPs in Ag@Au BNPs composite have a more chemical activity with respect to bare Ag NPs. Biosensor application of Ag@Au BNPs without probe immobilization is introduced too. The change in LSPR absorption peak of Ag@Au BNPs in presence of DNA primer decamer (ten-deoxycytosine) at fM concentrations is investigated. The LSPR absorption peak of Au NPs has a blue shift and the LSPR absorption peak of Ag NPs has a red shift by addition of DNA primer and under DNA exposure up to 1 h. Our sample shows a good response to low concentration of DNA and has a short response time. Both of these are prerequisite for applying this sample as LSPR biosensor chip.

  15. Application of Cryopreserved Fibroblast Culture with Au Nanoparticles to Treat Burns.

    PubMed

    Volkova, Nataliia; Yukhta, Mariia; Pavlovich, Olena; Goltsev, Anatoliy

    2016-12-01

    The aim was to investigate a possibility of using the cryopreserved human culture of fibroblasts (CrHFC) with gold nanoparticles (AuNPs) to treat experimental burns in rats.The third-degree burns were modeled in white male rats. All the animals with burns were divided into three experimental groups: control group with no wound treatment; group 1 was composed of animals with CrHFC application; and group 2 consisted of those with CrHFC and AuNPs (6 μg/ml) application to a burn surface the next day after the injury. The CrHFC was applied to the methylcellulose gel in a dose of 5 × 10(4) of viable cells per 1 cm(2) of the burn. The animals were removed from the experiment on day 21 after the treatment.The CrHFC use alone and with AuNPs to the surface of burns stimulated the wound healing compared with the control. The effect of using CrHFC was less pronounced compared to the CrHFC application with AuNPs. It was reflected in a slower recovery of burns and moderate lymphocytic infiltration of granulation tissue. Immunofluorescent analysis emphasized that the use of CrHFC with AuNPs accelerated the skin synthetic processes and was helpful in recovering type I and III collagen content on day 21 after therapy.The results were likely related primarily to the unique structure and antimicrobial properties of AuNPs. Our experimental study of the effect of CrHFC with AuNPs application on regenerative processes in burns gives some pre-conditions to the following advanced bio- and nanotechnology developments. PMID:26762263

  16. Virus-templated Au and Au/Pt Core/shell Nanowires and Their Electrocatalytic Activitives for Fuel Cell Applications

    PubMed Central

    LEE, YOUJIN; KIM, JUNHYUNG; YUN, DONG SOO; NAM, YOON SUNG; SHAO-HORN, YANG; BELCHER, ANGELA M.

    2014-01-01

    A facile synthetic route was developed to make Au nanowires (NWs) from surfactant-mediated bio-mineralization of a genetically engineered M13 phage with specific Au binding peptides. From the selective interaction between Au binding M13 phage and Au ions in aqueous solution, Au NWs with uniform diameter were synthesized at room temperature with yields greater than 98 % without the need for size selection. The diameters of Au NWs were controlled from 10 nm to 50 nm. The Au NWs were found to be active for electrocatalytic oxidation of CO molecules for all sizes, where the activity was highly dependent on the surface facets of Au NWs. This low-temperature high yield method of preparing Au NWs was further extended to the synthesis of Au/Pt core/shell NWs with controlled coverage of Pt shell layers. Electro-catalytic studies of ethanol oxidation with different Pt loading showed enhanced activity relative to a commercial supported Pt catalyst, indicative of the dual functionality of Pt for the ethanol oxidation and Au for the anti-poisoning component of Pt. These new one-dimensional noble metal NWs with controlled compositions could facilitate the design of new alloy materials with tunable properties. PMID:24910712

  17. Au dotted magnetic network nanostructure and its application for on-site monitoring femtomolar level pesticide.

    PubMed

    Yang, Tianxi; Guo, Xiaoyu; Wang, Hui; Fu, Shuyue; Yu, Jie; Wen, Ying; Yang, Haifeng

    2014-04-01

    A novel magnetically responsive and surface-enhanced Raman spectroscopy (SERS) active nanocomposite is designed and prepared by direct grafting of Au nanoparticles onto the surface of magnetic network nanostructure (MNN) with the help of a nontoxic and environmentally friendly reagent of inositol hexakisphosphate shortly named as IP6. The presence of IP6 as a stabilizer and a bridging agent could weave Fe3O4 nanoparticles (NPs) into magnetic network nanostructure, which is easily dotted with Au nanoparticles (Au NPs). It has been shown firstly that the huge Raman enhancement of Au-MNN is reached by an external magnetic collection. Au-MNN presenting the large surface and high detection sensitivity enables it to exhibit multifunctional applications involving sufficient adsorption of dissolved chemical species for enrichment, separation, as well as a Raman amplifier for the analysis of trace pesticide residues at femtomolar level by a portable Raman spectrometer. Therefore, such multifunctional nanocomposites can be developed as a smart and promising nanosystem that integrates SERS approach with an easy assay for concentration by an external magnet for the effective on-site assessments of agricultural and environmental safety. PMID:24130070

  18. Green synthesis and applications of Au-Ag bimetallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Meena Kumari, M.; Jacob, John; Philip, Daizy

    2015-02-01

    This paper reports for the first time the synthesis of bimetallic nanoparticles at room temperature using the fruit juice of pomegranate. Simultaneous reduction of gold and silver ions in different molar ratios leads to the formation of alloy as well as core-shell nanostructures. The nanoparticles have been characterized using UV-vis spectroscopy, transmission electron microscopy, Fourier Transform Infrared Spectroscopy and X-ray diffraction. The synthesized alloy particles are used as catalysts in the reduction of 2-, 3-, 4-nitrophenols to the corresponding amines and in the degradation of methyl orange. The reduction kinetics for all the reactions follows pseudo-first order. The rate constants follow the order k4-nitrophenol < k2-nitrophenol < k3-nitrophenol. Thermal conductivity is measured as a function of volume fraction and it is observed that the incorporation of the alloy nanoparticles enhances the thermal conductivity of the base fluid (water) showing nanofluid application. The nitric oxide and hydroxyl radical scavenging activity shown by the nanoparticles promise the potential application in biomedical field.

  19. Green synthesis and applications of Au-Ag bimetallic nanoparticles.

    PubMed

    Meena Kumari, M; Jacob, John; Philip, Daizy

    2015-02-25

    This paper reports for the first time the synthesis of bimetallic nanoparticles at room temperature using the fruit juice of pomegranate. Simultaneous reduction of gold and silver ions in different molar ratios leads to the formation of alloy as well as core-shell nanostructures. The nanoparticles have been characterized using UV-vis spectroscopy, transmission electron microscopy, Fourier Transform Infrared Spectroscopy and X-ray diffraction. The synthesized alloy particles are used as catalysts in the reduction of 2-, 3-, 4-nitrophenols to the corresponding amines and in the degradation of methyl orange. The reduction kinetics for all the reactions follows pseudo-first order. The rate constants follow the order k4-nitrophenolapplication. The nitric oxide and hydroxyl radical scavenging activity shown by the nanoparticles promise the potential application in biomedical field. PMID:25218228

  20. Colloidal Au-enhanced surface plasmon resonance imaging: application in a DNA hybridization process

    NASA Astrophysics Data System (ADS)

    Manera, M. G.; Spadavecchia, J.; Taurino, A.; Rella, R.

    2010-03-01

    The detection of the DNA hybridization mechanism using monodispersed gold nanoparticles as labels is an interesting alternative to increase the sensitivity of the SPR imaging technique. DNA-modified Au nanoparticles (DNA-Au NPs) containing single-stranded (ss) portions of DNA were prepared by monitoring their monolayer formation by UV-vis spectroscopy. The hybridization process between specific thio-oligonucleotides immobilized on the DNA-Au NPs and the corresponding complementary strands is reported and compared with the traditional hybridization process on properly self-assembled thin gold films deposited on glass substrates. A remarkable signal amplification is observed, following the incorporation of colloidal Au into a SPR biosensing experiment, resulting in an increased SPR response to DNA-DNA interactions. In particular Fusarium thiolated DNA (5'HS poly(T)15ATC CCT CAA AAA CTG CCG CT-3) and trichothecenes complementary DNA (5'-AGC GGC AGT TTT TGA GGG AT-3') sequences have been explored due to their possible application to agro-industry for the control of food quality.

  1. Large coincidence lattice on Au/Fe3O4 incommensurate structure for spintronic applications

    NASA Astrophysics Data System (ADS)

    Muñoz-Noval, Alvaro; Rubio-Zuazo, Juan; Salas-Colera, Eduardo; Serrano, Aida; Rubio-Marcos, Fernando; Castro, Germán R.

    2015-11-01

    The design of metallic hybrid systems for spintronics has been widely studied during the past decade, motivated by the promising technological applications of these materials. Nevertheless, the importance of preserving the native structure and properties of the interfaces is often ignored. Here, we present the fabrication of nanocrystalline Au (0 0 1) onto a single oriented Fe3O4 (0 0 1) thin film as a promising hybrid system to develop spintronic devices by growing Au over the Fe3O4 by using a simple one-pot Pulsed Laser Deposition (PLD) approach. The structural coupling between Au nanocrystals and Fe3O4 layer results in the development of an incommensurate structure based on a coincidence lattice of order 35, which preserves the intrinsic properties of the Au nanocrystals, the Fe3O4 matrix and the interface between them. The general strategy described in the present work preserves the structure and main intrinsic properties of the constituting materials, being a fundamental issue for the future development of spintronic devices.

  2. Application of Haddon’s matrix in qualitative research methodology: an experience in burns epidemiology

    PubMed Central

    Deljavan, Reza; Sadeghi-Bazargani, Homayoun; Fouladi, Nasrin; Arshi, Shahnam; Mohammadi, Reza

    2012-01-01

    Background Little has been done to investigate the application of injury specific qualitative research methods in the field of burn injuries. The aim of this study was to use an analytical tool (Haddon’s matrix) through qualitative research methods to better understand people’s perceptions about burn injuries. Methods This study applied Haddon’s matrix as a framework and an analytical tool for a qualitative research methodology in burn research. Both child and adult burn injury victims were enrolled into a qualitative study conducted using focus group discussion. Haddon’s matrix was used to develop an interview guide and also through the analysis phase. Results The main analysis clusters were pre-event level/human (including risky behaviors, belief and cultural factors, and knowledge and education), pre-event level/object, pre-event phase/environment and event and post-event phase (including fire control, emergency scald and burn wound management, traditional remedies, medical consultation, and severity indicators). This research gave rise to results that are possibly useful both for future injury research and for designing burn injury prevention plans. Conclusion Haddon’s matrix is applicable in a qualitative research methodology both at data collection and data analysis phases. The study using Haddon’s matrix through a qualitative research methodology yielded substantially rich information regarding burn injuries that may possibly be useful for prevention or future quantitative research. PMID:22866013

  3. Au/(Ti-W) and Au/Cr metallization of chemically vapor-deposited diamond substrates for multichip module applications

    NASA Astrophysics Data System (ADS)

    Meyyappan, Ilango; Malshe, A. P.; Naseem, H. A.; Brown, W. D.

    1994-12-01

    Since diamond obtained by chemical vapor deposition (CVD) has an extremely high thermal conductivity, it holds great promise in solving thermal management problems in high performance multichip modules (MCMs). Consequently, there is a need to develop a reliable metallization system for CVD diamond. Refractory metals such as Ti, Mo, Ta and W are known to form adhering carbide layers at high temperatures. Also, transition metals such as Cr, Ni and Ni-Cr are widely used in other MCM technologies involving Si, AlN, SiC and alumina substrates. In the work reported here, adherent Au/Cr and Au/(Ti-W) metallization systems were produced at low temperatures using d.c. magnetron sputtering and electron beam evaporation techniques. Adhesion at low temperature is essential since CVD diamond could lose its thermal and electrical properties at high temperatures. Furthermore, interaction between metal layers may cause an increase in conductor trace resistivity and delamination. Adhesion was measured using a Sebastian V-A thin film stud pull tester. The deposition parameters were optimized to give maximum adhesion using a statistical design software package, echip. In the case of the sputtered metallization, pre-sputter cleaning of diamond surface improved adhesion significantly. Values above 9 klbf/sq in were obtained in the case of Au/(Ti-W) and 11.8 klbf/sq in in the case of Au/Cr. Post-deposition annealing was performed in nitrogen ambient to investigate the effect of post-metallization processing on adhesion and also to test for any possible interaction between the metals at high temperatures. Annealing temperatures were limited to 450 C since MCM substrates are seldom exposed to temperatures higher than these. Energy-dispersive spectroscopy (EDS) analysis indicated outdiffusion of W through Au at 400 deg C. No interdiffusion was observed in the case of Au/Cr as per optical microscopy and EDS analysis. Auger electron spectroscopy results indicate interaction between the

  4. Synthesis, characterization and application of Au-198 nanoparticles as radiotracer for industrial applications.

    PubMed

    Goswami, Sunil; Pant, H J; Biswal, Jayashree; Samantray, J S; Sharma, V K; Dash, Ashutosh

    2016-05-01

    This paper describes synthesis and characterization of radioactive gold nanoparticles ((198)Au-NPs), and explores their utility as a radiotracer for tracing an aqueous phase in a continuous laboratory-scale bubble column at ambient conditions. The performance of the (198)Au-NPs as a radiotracer was compared with the results obtained with a conventional radiotracer i.e. bromine-82 ((82)Br) as ammonium bromide and found to be identical. A tank-in-series with backmixing model (TISBM) was used to simulate the RTDs of the aqueous phase and characterize flow in the bubble column. PMID:26897465

  5. Mo6S3I6-Au composites: synthesis, conductance, and applications.

    PubMed

    Zhang, Renyun; Hummelgård, Magnus; Dvorsek, Damjan; Mihailovic, Dragan; Olin, Håkan

    2010-08-15

    A single-step, premixing method was used to directly deposit gold nanoparticles on Mo(6)S(3)I(6) (MSI) molecular wire bundles. Gold nanoparticles with different sizes and densities were coated on the MSI by changing the concentration of the gold containing salt, HAuCl(4). TEM, SEM, and EDX characterization showed deposition of gold nanoparticles on the MSI nanowire surface. The electrical resistance of these MSI-Au composites was more than 100 times lower than that for pure MSI, and was mainly dependent on the density of the deposited gold nanoparticles. Furthermore, we immobilized thiol group-labeled oligonucleotide on the composites and then hybridized with a fully matched sequence. The resistance of the MSI-Au composites increased during the thiol step, while it decreased by hybridizing, due to the conductance difference between single- and double-stranded DNA chains. These results indicate that this new kind of MSI-Au composite could be used as a platform for different applications, including biosensors. PMID:20494366

  6. Ionic liquid functionalized graphene/Au nanocomposites and its application for electrochemical immunosensor.

    PubMed

    Liu, Na; Chen, Xia; Ma, Zhanfang

    2013-10-15

    In this work, a new nanocomposite, which was composed of ionic liquid functionalized graphene sheet (IL-GS) loaded gold nanoparticles (AuNPs), was prepared. The IL-GS was directly synthesized by the electrochemical exfoliation of graphite in ionic liquid (IL). Due to the modification of the IL, IL-GS can not only be dispersed easily in aqueous solution to form a homogeneous colloidal suspension of individual sheet, but also exhibits an improved conductivity. Meanwhile, the loaded AuNPs on the nanocomposites can increase the specific surface area to capture a large amount of antibodies as well as improve the capability of electron transfer. The IL-GS-Au nanocomposites were successfully employed for the fabrication of a facile and sensitive electrochemical immunosensor. Carcinoembryonic antigen (CEA) was used as a model protein. The proposed immunosensor exhibits a wide linear detection range (LDR) from 1 fg mL⁻¹ to 100 ng mL⁻¹, and an ultralow limit of detection (LOD) of 0.1 fg mL⁻¹ (S/N=3). In addition, for the detection of clinical serum samples, it is well consistent with the data determined by the developed immunoassay and ELISA, indicating that the immunosensor provides a possible application for the detection of CEA in clinical diagnostics. PMID:23644143

  7. Ellagic Acid Directed Growth of Au-Pt Bimetallic Nanoparticles and Their Catalytic Applications

    NASA Astrophysics Data System (ADS)

    Barnaby, Stacey N.; Sarker, Nazmul H.; Banerjee, Ipsita A.

    2013-02-01

    In this work, we report the facile formation of bimetallic nanoparticles of Au-Pt in the presence of the plant polyphenol ellagic acid (EA). It was found that EA formed micro-fibrillar assemblies, which aggregated into micro-bundles under aqueous conditions. Those micro-bundles acted as templates for the growth of Au nanoparticles, as well as bimetallic Au-Pt nanoparticles biomimetically. At higher concentrations of EA, it was observed that in addition to forming fibrous micro-bundles, columnar assemblies of EA were formed in the presence of the metal nanoparticles. The formation of the assemblies was found to be concentration dependent. It appears that upon binding to metal ions and subsequent formation of the nanoparticles, morphological changes occur in the case of EA assemblies. The morphological changes observed were probed by electron microscopy. Further, the ability of the materials to degrade the toxic aromatic nitro compound 2-methoxy-4-nitroaniline was explored, where 50% degradation was observed within 15 min, indicating that such hybrid materials may have potential applications in environmental remediation.

  8. Plasmonic effects of au/ag bimetallic multispiked nanoparticles for photovoltaic applications.

    PubMed

    Sharma, Manisha; Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Vinogradova, Ekaterina; Ayon, Arturo A

    2014-09-10

    In recent years, there has been considerable interest in the use of plasmons, that is, free electron oscillations in conductors, to boost the performance of both organic and inorganic thin film solar cells. This has been driven by the possibility of employing thin active layers in solar cells in order to reduce materials costs, and is enabled by significant advances in fabrication technology. The ability of surface plasmons in metallic nanostructures to guide and confine light in the nanometer scale has opened up new design possibilities for solar cell devices. Here, we report the synthesis and characterization of highly monodisperse, reasonably stable, multipode Au/Ag bimetallic nanostructures using an inorganic additive as a ligand for photovoltaic applications. A promising surface enhanced Raman scattering (SERS) effect has been observed for the synthesized bimetallic Au/Ag multispiked nanoparticles, which compare favorably well with their Au and Ag spherical nanoparticle counterparts. The synthesized plasmonic nanostructures were incorporated on the rear surface of an ultrathin planar c-silicon/organic polymer hybrid solar cell, and the overall effect on photovoltaic performance was investigated. A promising enhancement in solar cell performance parameters, including both the open circuit voltage (VOC) and short circuit current density (JSC), has been observed by employing the aforementioned bimetallic multispiked nanoparticles on the rear surface of solar cell devices. A power conversion efficiency (PCE) value as high as 7.70% has been measured in a hybrid device with Au/Ag multispiked nanoparticles on the rear surface of an ultrathin, crystalline silicon (c-Si) membrane (∼ 12 μm). This value compares well to the measured PCE value of 6.72% for a similar device without nanoparticles. The experimental observations support the hope for a sizable PCE increase, due to plasmon effects, in thin-film, c-Si solar cells in the near future. PMID:25137194

  9. Educators' and Applicants' Views of the Postdoctoral Pediatric Dentistry Admission Process: A Qualitative Study.

    PubMed

    Ricker, Kevin; Mihas, Paul; Lee, Jessica Y; Guthmiller, Janet M; Roberts, Michael W; Divaris, Kimon

    2015-11-01

    The postdoctoral application and matching process in dental education is a high-stakes and resource-intensive process for all involved. While programs seek the most qualified candidates, applicants strive to be competitive to increase their likelihood of being accepted to a desirable program. There are limited data regarding either subjective or objective factors underlying the complex interplay between programs and applicants. This qualitative study sought to provide insight into the stakeholders' experiences and views on the matching process. Telephone and in-person interviews were conducted with ten pediatric dentistry program directors and ten recent applicants to pediatric dentistry programs in the United States in 2013-14. Participants were selected to represent the geographic (five districts of the American Academy of Pediatric Dentistry) and institutional (hospital- or university-based) diversity of pediatric dentistry programs. Interviews were recorded and transcribed verbatim. Veracity and need for more information were the themes most often articulated by both groups. The program directors most valued teachability and self-motivation as desirable applicant characteristics. The applicants relied primarily on subjective sources to gather information about programs and prioritized location and financial factors as pivotal for their rankings. Both groups appreciated the uniformity of the current application process and highlighted several weaknesses and areas for improvement. These results shed light on the postdoctoral matching process in pediatric dentistry via a qualitative description of stakeholders' experiences and viewpoints. These insights can serve as a basis for improving and refining the matching process. PMID:26522631

  10. Learning Qualitative Differential Equation models: a survey of algorithms and applications

    PubMed Central

    PANG, WEI; COGHILL, GEORGE M.

    2013-01-01

    Over the last two decades, qualitative reasoning (QR) has become an important domain in Artificial Intelligence. QDE (Qualitative Differential Equation) model learning (QML), as a branch of QR, has also received an increasing amount of attention; many systems have been proposed to solve various significant problems in this field. QML has been applied to a wide range of fields, including physics, biology and medical science. In this paper, we first identify the scope of this review by distinguishing QML from other QML systems, and then review all the noteworthy QML systems within this scope. The applications of QML in several application domains are also introduced briefly. Finally, the future directions of QML are explored from different perspectives. PMID:23704803

  11. A new method for qualitative simulation of water resources systems: 2. Applications

    NASA Astrophysics Data System (ADS)

    Antunes, M. P.; Seixas, M. J.; Camara, A. S.; Pinheiro, M.

    1987-11-01

    SLIN (Simulação Linguistica) is a new method for qualitative dynamic simulation. As was presented previously (Camara et al., this issue), SLIN relies upon a categorical representation of variables which are manipulated by logical rules. Two applications to water resources systems are included to illustrate SLIN's potential usefulness: the environmental impact evaluation of a hydropower plant and the assessment of oil dispersion in the sea after a tanker wreck.

  12. Nanocomposite of Au Nanoparticles/Helical Carbon Nanofibers and Application in Hydrogen Peroxide Biosensor.

    PubMed

    Zhai, Mumu; Cui, Rongjing; Gu, Ning; Zhang, Genhua; Lin, Wang; Yu, Lingjun

    2015-06-01

    A combined sol-gel/hydrogen reduction method has been developed for the mass production of helical carbon nanofibers (HCNFs) by the pyrolysis of acetylene at 425 degrees C in the presence of NiO nanoparticles. The synthesized HCNFs were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The helical-structured carbon nanofibers have a large specific surface area and excellent biocompatibility. A novel enzymatic hydrogen peroxide sensor was then successfully fabricated based on the nanocomposites containing HCNFs and gold nanoparticles (AuNPs). The results indicated that the Au/HCNFs nanocomposites exhibited excellent electrocatalytic activity to the reduction of H2O2, offering a wide linear range from 1.0 μM to 3157 μM with a detection limit as low as 0.46 μM. The apparent Michaelis-Menten constant of the biosensor was 0.61 mM. The as-fabricated biosensor showed a rapid and sensitive amperometric response to hydrogen peroxide with acceptable preparation reproducibility and excellent stability. Because of their low cost and high stability, these novel HCNFs represent seem to be a kind of promising biomaterial and may find wide new applications in scopes such as biocatalysis, immunoassay, environmental monitoring and so on. PMID:26369097

  13. Developing a Brief Suicide Prevention Intervention and Mobile Phone Application: a Qualitative Report

    PubMed Central

    Kennard, Beth D; Biernesser, Candice; Wolfe, Kristin L; Foxwell, Aleksandra A; Craddock Lee, Simon J; Rial, Katie V; Patel, Sarita; Cheng, Carol; Goldstein, Tina; McMakin, Dana; Blastos, Beatriz; Douaihy, Antoine; Zelazny, Jamie; Brent, David A

    2015-01-01

    Suicide is the second leading cause of death among youth and has become a serious public health problem. There has been limited research on strategies to decrease the likelihood of reattempt in adolescents. As phase one of a treatment development study, clinicians, parents and adolescents participated in qualitative interviews in order to gain new perspectives on developing a targeted intervention and a safety plan phone application for suicide prevention. Participants indicated that transition of care, specific treatment targets and safety planning were important parts of treatment. In addition, all participants endorsed the use of a smartphone application for these purposes. PMID:26977137

  14. Preparation of Ag/Au bimetallic nanostructures and their application in surface-enhanced fluorescence.

    PubMed

    Dong, Jun; Ye, Yanyan; Zhang, Wenhui; Ren, Zebin; Huo, Yiping; Zheng, Hairong

    2015-11-01

    An effective substrate for surface-enhanced fluorescence, which consists of cluster Ag/Au bimetallic nanostructures on a copper surface, was synthesized via a multi-stage galvanic replacement reaction of a Ag cluster in a chlorauric acid (HAuCl4) solution at room temperature. The fabricated silver/gold bimetallic cluster were found to yield large surface-enhanced fluorescence (SEF) enhancement factors for rhodamine 6G probe molecules deposited on the substrate, and also the fluorescence efficiency is critically dependent on the period of nanostructure growth. With the help of proper control reaction conditions, such as the reaction time, and concentration of reaction solutions, the maximum fluorescence enhanced effect was obtained. Therefore, the bimetallic nanostructure substrate also can be adapted to studies in SEF, which will expand the application of SEF. PMID:25691287

  15. Modelisation et commande des redresseurs triphases fonctionnant a haut rendement et a faible taux de distorsion harmonique: Application au redresseur triphase de vienne

    NASA Astrophysics Data System (ADS)

    Belhadj Youssef, Nesrine

    Les problemes de la qualite de l'onde electrique constituent l'une des preoccupations majeures des fournisseurs de l'energie et des organismes specialises en qualite d'energie. Ce sujet a gagne davantage d'ampleur avec l'utilisation ascendante des convertisseurs de l'energie electrique dans la majorite des applications industrielles et domestiques. Dans le cadre de cette these, on s'interesse plus particulierement au type des convertisseurs alternatif/continu, dont le fonctionnement adequat implique la parfaite regulation du bus DC de tension, l'attenuation des harmoniques de courants, la compensation de l'energie reactive et la maximisation du rendement energetique. Ces differents criteres doivent etre maintenus pour diverses conditions de fonctionnement, c'est-a-dire independamment des variations parametriques auxquelles le systeme peut etre sujet. Il s'avere donc indispensable d'adopter des techniques de commande efficaces, ce qui passe par une modelisation correcte du convertisseur. L'optimisation du nombre de capteurs dans le circuit est egalement un facteur cle a prendre en consideration.

  16. Kinetically controlled synthesis of Au102(SPh)44 nanoclusters and catalytic application

    NASA Astrophysics Data System (ADS)

    Chen, Yongdong; Wang, Jin; Liu, Chao; Li, Zhimin; Li, Gao

    2016-05-01

    We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent thiophenol ligands, evidenced by the analyses of UV-vis and MALDI mass spectrometry. Finally, the TiO2-supported Au102(SPh)44 nanocluster catalyst is investigated in the selective oxidation of sulfides into sulfoxides by the PhIO oxidant and gives rise to high catalytic activity (e.g., 80-99% conversion of R-S-R' sulfides with 96-99% selectivity for R-S(&z.dbd;O)-R' sulfoxides). The Au102(SPh)44/TiO2 catalyst also shows excellent recyclability in the sulfoxidation process.We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent

  17. Pd-on-Au Supra-nanostructures Decorated Graphene Oxide: An Advanced Electrocatalyst for Fuel Cell Application.

    PubMed

    Tao, Yingzhou; Dandapat, Anirban; Chen, Liming; Huang, Youju; Sasson, Yoel; Lin, Zhenyu; Zhang, Jiawei; Guo, Longhua; Chen, Tao

    2016-08-30

    We report a very easy and effective approach for synthesizing unique palladium-on-gold supra-nanostructure (Au@Pd-SprNS)-decorated graphene oxide (GO) nanosheets. The SprNSs comprising Au nanorods as core and a unique close-packed assembly of tiny anisotropic Pd nanoparticles (NPs) as shell were homogeneously distributed on the GO surface via electrostatic self-assembly. Compared with the traditional one-pot method for synthesis of metal NPs on GO sheets, the size and shape of core-shell Au@Pd SprNSs can be finely controlled and uniformly distributed on the GO carrier. Interestingly, this Au@Pd-SprNSs/GO nanocomposite displayed high electrocatalytic activities toward the oxidation of methanol, ethanol, and formic acid, which can be attributed to the abundance of intrinsic active sites including high density of atomic steps, ledges and kinks, Au-Pd heterojunctions and cooperative action of the two metals of the SprNSs. Additionally, uniform dispersion of the SprNSs over the GO nanosheets prevent agglomeration between the SprNSs, which is of great significance to enhance the long-term stability of catalyst. This work will introduce a highly efficient Pd-based nanoelectrocatalyst to be used in fuel cell application. PMID:27482606

  18. Kinetically controlled synthesis of Au102(SPh)44 nanoclusters and catalytic application.

    PubMed

    Chen, Yongdong; Wang, Jin; Liu, Chao; Li, Zhimin; Li, Gao

    2016-05-21

    We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent thiophenol ligands, evidenced by the analyses of UV-vis and MALDI mass spectrometry. Finally, the TiO2-supported Au102(SPh)44 nanocluster catalyst is investigated in the selective oxidation of sulfides into sulfoxides by the PhIO oxidant and gives rise to high catalytic activity (e.g., 80-99% conversion of R-S-R' sulfides with 96-99% selectivity for R-S([double bond, length as m-dash]O)-R' sulfoxides). The Au102(SPh)44/TiO2 catalyst also shows excellent recyclability in the sulfoxidation process. PMID:26758553

  19. Electrical performance of Ti-ZnO-Au thin film composite structure for device application

    NASA Astrophysics Data System (ADS)

    Joshi, Priyanka; Singh, Jitendra; Das, Surajit; Desai, J. V.; Akhtar, Jamil

    2016-04-01

    Thin film layers of Au/Ti approximately 2200 Å thick and ZnO approximately 2.24 µm thick were sputtered sequentially onto silicon dioxide coated <100> Si-wafer. Conventional wisdom confirms the adhesion of gold over zinc oxide (ZnO) by an intermediate layer of titanium for better adhesion. But, in Au/Ti/ZnO/Au/Ti structure, it was observed that with the passing of time the gold diffused into ZnO thin film at room temperature, making a very low resistance between the two gold layers eventually making a conductive path in ZnO. Therefore, electrical connectivity was found between the metal layers. A detailed experimental analysis has been carried out in support of the observed Au diffusion. In the present work, reliability of Ti/Au metallisation and anomalous electrical behavior due to gold diffusion has been studied.

  20. How and why do interviewers try to make impressions on applicants? A qualitative study.

    PubMed

    Wilhelmy, Annika; Kleinmann, Martin; König, Cornelius J; Melchers, Klaus G; Truxillo, Donald M

    2016-03-01

    To remain viable in today's highly competitive business environments, it is crucial for organizations to attract and retain top candidates. Hence, interviewers have the goal not only of identifying promising applicants but also of representing their organization. Although it has been proposed that interviewers' deliberate signaling behaviors are a key factor for attracting applicants and thus for ensuring organizations' success, no conceptual model about impression management (IM) exists from the viewpoint of the interviewer as separate from the applicant. To develop such a conceptual model on how and why interviewers use IM, our qualitative study elaborates signaling theory in the interview context by identifying the broad range of impressions that interviewers intend to create on applicants, what kinds of signals interviewers deliberately use to create their intended impressions, and what outcomes they pursue. Following a grounded theory approach, multiple raters analyzed in-depth interviews with interviewers and applicants. We also observed actual employment interviews and analyzed memos and image brochures to generate a conceptual model of interviewer IM. Results showed that the spectrum of interviewers' IM intentions goes well beyond what has been proposed in past research. Furthermore, interviewers apply a broad range of IM behaviors, including verbal and nonverbal as well as paraverbal, artifactual, and administrative behaviors. An extensive taxonomy of interviewer IM intentions, behaviors, and intended outcomes is developed, interrelationships between these elements are presented, and avenues for future research are derived. PMID:26436440

  1. Crystallographic investigation of Au nanoparticles embedded in a SrTiO3 thin film for plasmonics applications by means of synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Pincini, Davide; Mazzoli, Claudio; Bernhardt, Hendrik; Katzer, Christian; Schmidl, Frank; Uschmann, Ingo; Detlefs, Carsten

    2015-03-01

    Self-organized monocrystalline Au nanoparticles with potential applications in plasmonics are grown in a SrTiO3 matrix by a novel two-step deposition process. The crystalline preferred orientation of these Au nanoparticles is investigated by synchrotron hard x-ray diffraction. Nanoparticles preferentially align with the (111) direction along the substrate normal (001), whereas two in-plane orientations are found with [ 110 ] SrTiO3 ∥ [ 110 ] Au and [ 100 ] SrTiO3 ∥ [ 110 ] Au . Additionally, a smaller diffraction signal from nanoparticles with the (001) direction parallel to the substrate normal (001) is observed; once again, two in-plane orientations are found, with [ 100 ] SrTiO3 ∥ [ 100 ] Au and [ 100 ] SrTiO3 ∥ [ 110 ] Au . The populations of the two in-plane orientations are found to depend on the thickness of the gold film deposited in the first step of the growth.

  2. Facile Synthesis of Quasi-One-Dimensional Au/PtAu Heterojunction Nanotubes and Their Application as Catalysts in an Oxygen-Reduction Reaction.

    PubMed

    Cai, Kai; Liu, Jiawei; Zhang, Huan; Huang, Zhao; Lu, Zhicheng; Foda, Mohamed F; Li, Tingting; Han, Heyou

    2015-05-11

    An intermediate-template-directed method has been developed for the synthesis of quasi-one-dimensional Au/PtAu heterojunction nanotubes by the heterogeneous nucleation and growth of Au on Te/Pt core-shell nanostructures in aqueous solution. The synthesized porous Au/PtAu bimetallic nanotubes (PABNTs) consist of porous tubular framework and attached Au nanoparticles (AuNPs). The reaction intermediates played an important role in the preparation, which fabricated the framework and provided a localized reducing agent for the reduction of the Au and Pt precursors. The Pt7 Au PABNTs showed higher electrocatalytic activity and durability in the oxygen-reduction reaction (ORR) in 0.1 M HClO4 than porous Pt nanotubes (PtNTs) and commercially available Pt/C. The mass activity of PABNTs was 218 % that of commercial Pt/C after an accelerated durability test. This study demonstrates the potential of PABNTs as highly efficient electrocatalysts. In addition, this method provides a facile strategy for the synthesis of desirable hetero-nanostructures with controlled size and shape by utilizing an intermediate template. PMID:25833689

  3. Fabrication of Te and Te-Au Nanowires-Based Carbon Fiber Fabrics for Antibacterial Applications

    PubMed Central

    Chou, Ting-Mao; Ke, Yi-Yun; Tsao, Yu-Hsiang; Li, Ying-Chun; Lin, Zong-Hong

    2016-01-01

    Pathogenic bacteria that give rise to diseases every year remain a major health concern. In recent years, tellurium-based nanomaterials have been approved as new and efficient antibacterial agents. In this paper, we developed the approach to directly grow tellurium nanowires (Te NWs) onto commercial carbon fiber fabrics and demonstrated their antibacterial activity. Those Te NWs can serve as templates and reducing agents for gold nanoparticles (Au NPs) to deposit. Three different Te-Au NWs with varied concentration of Au NPs were synthesized and showed superior antibacterial activity and biocompability. These results indicate that the as-prepared carbon fiber fabrics with Te and Te-Au NWs can become antimicrobial clothing products in the near future. PMID:26861380

  4. Peer Review of Grant Applications: Criteria Used and Qualitative Study of Reviewer Practices

    PubMed Central

    Abdoul, Hendy; Perrey, Christophe; Amiel, Philippe; Tubach, Florence; Gottot, Serge; Durand-Zaleski, Isabelle; Alberti, Corinne

    2012-01-01

    Background Peer review of grant applications has been criticized as lacking reliability. Studies showing poor agreement among reviewers supported this possibility but usually focused on reviewers’ scores and failed to investigate reasons for disagreement. Here, our goal was to determine how reviewers rate applications, by investigating reviewer practices and grant assessment criteria. Methods and Findings We first collected and analyzed a convenience sample of French and international calls for proposals and assessment guidelines, from which we created an overall typology of assessment criteria comprising nine domains relevance to the call for proposals, usefulness, originality, innovativeness, methodology, feasibility, funding, ethical aspects, and writing of the grant application. We then performed a qualitative study of reviewer practices, particularly regarding the use of assessment criteria, among reviewers of the French Academic Hospital Research Grant Agencies (Programmes Hospitaliers de Recherche Clinique, PHRCs). Semi-structured interviews and observation sessions were conducted. Both the time spent assessing each grant application and the assessment methods varied across reviewers. The assessment criteria recommended by the PHRCs were listed by all reviewers as frequently evaluated and useful. However, use of the PHRC criteria was subjective and varied across reviewers. Some reviewers gave the same weight to each assessment criterion, whereas others considered originality to be the most important criterion (12/34), followed by methodology (10/34) and feasibility (4/34). Conceivably, this variability might adversely affect the reliability of the review process, and studies evaluating this hypothesis would be of interest. Conclusions Variability across reviewers may result in mistrust among grant applicants about the review process. Consequently, ensuring transparency is of the utmost importance. Consistency in the review process could also be improved by

  5. Au nanostructure arrays for plasmonic applications: annealed island films versus nanoimprint lithography.

    PubMed

    Lopatynskyi, Andrii M; Lytvyn, Vitalii K; Nazarenko, Volodymyr I; Guo, L Jay; Lucas, Brandon D; Chegel, Volodymyr I

    2015-01-01

    This paper attempts to compare the main features of random and highly ordered gold nanostructure arrays (NSA) prepared by thermally annealed island film and nanoimprint lithography (NIL) techniques, respectively. Each substrate possesses different morphology in terms of plasmonic enhancement. Both methods allow such important features as spectral tuning of plasmon resonance position depending on size and shape of nanostructures; however, the time and cost is quite different. The respective comparison was performed experimentally and theoretically for a number of samples with different geometrical parameters. Spectral characteristics of fabricated NSA exhibited an expressed plasmon peak in the range from 576 to 809 nm for thermally annealed samples and from 606 to 783 nm for samples prepared by NIL. Modelling of the optical response for nanostructures with typical shapes associated with these techniques (parallelepiped for NIL and semi-ellipsoid for annealed island films) was performed using finite-difference time-domain calculations. Mathematical simulations have indicated the dependence of electric field enhancement on the shape and size of the nanoparticles. As an important point, the distribution of electric field at so-called 'hot spots' was considered. Parallelepiped-shaped nanoparticles were shown to yield maximal enhancement values by an order of magnitude greater than their semi-ellipsoid-shaped counterparts; however, both nanoparticle shapes have demonstrated comparable effective electrical field enhancement values. Optimized Au nanostructures with equivalent diameters ranging from 85 to 143 nm and height equal to 35 nm were obtained for both techniques, resulting in the largest electrical field enhancement. The application of island film thermal annealing method for nanochips fabrication can be considered as a possible cost-effective platform for various surface-enhanced spectroscopies; while the NIL-fabricated NSA looks like more effective for

  6. Au nanostructure arrays for plasmonic applications: annealed island films versus nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Lopatynskyi, Andrii M.; Lytvyn, Vitalii K.; Nazarenko, Volodymyr I.; Guo, L. Jay; Lucas, Brandon D.; Chegel, Volodymyr I.

    2015-03-01

    This paper attempts to compare the main features of random and highly ordered gold nanostructure arrays (NSA) prepared by thermally annealed island film and nanoimprint lithography (NIL) techniques, respectively. Each substrate possesses different morphology in terms of plasmonic enhancement. Both methods allow such important features as spectral tuning of plasmon resonance position depending on size and shape of nanostructures; however, the time and cost is quite different. The respective comparison was performed experimentally and theoretically for a number of samples with different geometrical parameters. Spectral characteristics of fabricated NSA exhibited an expressed plasmon peak in the range from 576 to 809 nm for thermally annealed samples and from 606 to 783 nm for samples prepared by NIL. Modelling of the optical response for nanostructures with typical shapes associated with these techniques (parallelepiped for NIL and semi-ellipsoid for annealed island films) was performed using finite-difference time-domain calculations. Mathematical simulations have indicated the dependence of electric field enhancement on the shape and size of the nanoparticles. As an important point, the distribution of electric field at so-called `hot spots' was considered. Parallelepiped-shaped nanoparticles were shown to yield maximal enhancement values by an order of magnitude greater than their semi-ellipsoid-shaped counterparts; however, both nanoparticle shapes have demonstrated comparable effective electrical field enhancement values. Optimized Au nanostructures with equivalent diameters ranging from 85 to 143 nm and height equal to 35 nm were obtained for both techniques, resulting in the largest electrical field enhancement. The application of island film thermal annealing method for nanochips fabrication can be considered as a possible cost-effective platform for various surface-enhanced spectroscopies; while the NIL-fabricated NSA looks like more effective for sensing of

  7. Stabilization of AuNPs by monofunctional triazole linked to ferrocene, ferricenium, or coumarin and applications to synthesis, sensing, and catalysis.

    PubMed

    Li, Na; Zhao, Pengxiang; Igartua, María E; Rapakousiou, Amalia; Salmon, Lionel; Moya, Sergio; Ruiz, Jaime; Astruc, Didier

    2014-11-01

    Monofunctional triazoles linked to ferrocene, ferricenium, or coumarin (Cou), easily synthesized by copper-catalyzed azide alkyne (CuAAC) "click" reactions between the corresponding functional azides and (trimethylsilyl)acetylene followed by silyl group deprotection, provide a variety of convenient neutral ligands for the stabilization of functional gold nanoparticles (AuNPs) in polar organic solvents. These triazole (trz)-AuNPs are very useful toward a variety of applications to synthesis, sensing, and catalysis. Both ferrocenyl (Fc) and isostructural ferricenium linked triazoles give rise to AuNP stabilization, although by different synthetic routes. Indeed, the first direct synthesis and stabilization of AuNPs by ferricenium are obtained by the reduction of HAuCl4 upon reaction with a ferrocene derivative, AuNP stabilization resulting from a synergy between electrostatic and coordination effects. The ferricenium/ferrocene trz-AuNP redox couple is fully reversible, as shown by cyclic voltammograms that were recorded with both redox forms. These trz-AuNPs are stable for weeks in various polar solvents, but at the same time, the advantage of trz-AuNPs is the easy substitution of neutral trz ligands by thiols and other ligands, giving rise to applications. Indeed, this ligand substitution of trz at the AuNP surface yields a stable Fc-terminated nanogold-cored dendrimer upon reaction with a Fc-terminated thiol dendron, substitution of Cou-linked trz with cysteine, homocysteine, and glutathione provides remarkably efficient biothiol sensing, and a ferricenium-linked trz-AuNP catalyst is effective for NaBH4 reduction of 4-nitrophenol to 4-aminophenol. In this catalytic example, the additional electrostatic AuNP stabilization modulates the reaction rate and induction time. PMID:25363304

  8. Composition-selective fabrication of ordered intermetallic Au-Cu nanowires and their application to nano-size electrochemical glucose detection

    NASA Astrophysics Data System (ADS)

    Kim, Si-In; Eom, Gayoung; Kang, Mijeong; Kang, Taejoon; Lee, Hyoban; Hwang, Ahreum; Yang, Haesik; Kim, Bongsoo

    2015-06-01

    Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures.

  9. Composition-selective fabrication of ordered intermetallic Au-Cu nanowires and their application to nano-size electrochemical glucose detection.

    PubMed

    Kim, Si-In; Eom, Gayoung; Kang, Mijeong; Kang, Taejoon; Lee, Hyoban; Hwang, Ahreum; Yang, Haesik; Kim, Bongsoo

    2015-06-19

    Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures. PMID:26016531

  10. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application.

    PubMed

    Slaughter, Gymama; Stevens, Brian

    2015-01-01

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 mW/ cm² in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm², respectively. PMID:26580661

  11. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application

    PubMed Central

    Slaughter, Gymama; Stevens, Brian

    2015-01-01

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 μW/ cm2 in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm2, respectively. PMID:26580661

  12. Nonlinear stability of solar type 3 radio bursts. 2: Application to observations near 1 AU

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Smith, R. A.; Papadopoulos, K.

    1978-01-01

    A set of rate equations including strong turbulence effects and anomalous resitivity are solved using parmeters which model several solar type 3 bursts. Exciter distributions observed at 1 AU are excitation of the linear bump-in-tail instability, amplifying Langmuir waves above the threshold for the oscillating two stream instability (OTSI). The OTSI, and the attendant anomalous resistivity produce a rapid spectral transfer of Langmuir waves to short wavelengths, out of resonance with the electron exciter. Further energy loss of the beam is thus precluded. The various parameters needed to model the bursts are extrapolated inside 1 AU with similar results. Again, the OTSI is excited and decouples the electron beam from the Langmuir radiation. Reabsorption of the Langmuir waves by the beam is shown to be unimportant in all cases, even at 0.1 AU. The theory provides a natural explanation for the observed realationship between radio flux, and the electron flux.

  13. Cyclotron produced 198gAu, a potential radionuclide for diagnostic and therapeutic applications

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Haba, Hiromitsu; Kassim, Hasan Abu

    2016-02-01

    Production cross-sections of the natPt(d,x)198Au reactions have been measured from a 24-MeV deuteron energy down to the threshold by using a stacked-foil activation technique combined with HPGe γ-ray spectrometry. Only a partial agreement is obtained with the existing literature data and the theoretical data extracted from the TENDL-2013 library. Physical thick target yield for the 198Au radionuclide was deduced using the measured cross-sections, and found a general agreement with the directly measured yield available in the literature. This study reveals that a low deuteron energy (<15 MeV) cyclotron and an enriched 198Pt (100%) target could be used to obtain 198Au in no carrier added form.

  14. Production of radio-gold 199Au for diagnostic and therapeutic applications

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Haba, Hiromitsu; Kassim, Hasan Abu

    2016-01-01

    Production cross-sections of the natPt(d,x)199Au reactions have been measured from a 24-MeV deuteron energy down to the threshold by using a stacked-foil activation technique combined with HPGe γ-ray spectrometry. Only a partial agreement is obtained with the existing literature data. Theoretical data extracted from the TENDL-2013 library shows large discrepancy with the measured ones. Physical thick target yield for the 199Au radionuclide was deduced using the measured cross-sections, and found a general agreement with the directly measured yield available in the literature. This study reveals that a low deuteron energy (<15 MeV) cyclotron and an enriched 198Pt (100%) target could be used to obtain 199Au in no carrier added form.

  15. Controlled preparation of Au/Ag/SnO2 core-shell nanoparticles using a photochemical method and applications in LSPR based sensing

    NASA Astrophysics Data System (ADS)

    Zhou, Na; Ye, Chen; Polavarapu, Lakshminarayana; Xu, Qing-Hua

    2015-05-01

    A photochemical method for the controlled preparation of core-shell Au/Ag/SnO2 nanorods (NRs) and nanospheres (NSs) has been developed based on photo-induced electron transfer processes in the plasmonic metal-semiconductor system. Au/AgNR/SnO2 and Au/AgNS/SnO2 were prepared by the UV irradiation of a mixture of mesoporous SnO2 coated AuNRs, or AuNSs, and AgNO3, in which AgNO3 was reduced by electrons transferred from the photo-excited mesoporous SnO2 (semiconductor) to the gold (metal). This method allows precise control over the composition and optical properties of the obtained nanoparticles. The LSPR refractive index sensitivity of the obtained Au/AgNR/SnO2 nanoparticles has been optimized to obtain a refractive index sensitivity of ~442 nm RIU-1. The optimized nanoparticles were subsequently chosen for the LSPR based sensing of glutathione (GSH) with the limit of detection of ~7.5 × 10-7 M. This photochemical method allows the controlled preparation of various Au/Ag/SnO2 nanoparticles to adjust their LSPR to suit various applications.A photochemical method for the controlled preparation of core-shell Au/Ag/SnO2 nanorods (NRs) and nanospheres (NSs) has been developed based on photo-induced electron transfer processes in the plasmonic metal-semiconductor system. Au/AgNR/SnO2 and Au/AgNS/SnO2 were prepared by the UV irradiation of a mixture of mesoporous SnO2 coated AuNRs, or AuNSs, and AgNO3, in which AgNO3 was reduced by electrons transferred from the photo-excited mesoporous SnO2 (semiconductor) to the gold (metal). This method allows precise control over the composition and optical properties of the obtained nanoparticles. The LSPR refractive index sensitivity of the obtained Au/AgNR/SnO2 nanoparticles has been optimized to obtain a refractive index sensitivity of ~442 nm RIU-1. The optimized nanoparticles were subsequently chosen for the LSPR based sensing of glutathione (GSH) with the limit of detection of ~7.5 × 10-7 M. This photochemical method allows

  16. Au-coated ZnO nanostructures for surface enhanced Raman spectroscopy applications

    SciTech Connect

    Dikovska, A O; Nedyalkov, N N; Imamova, S E; Atanasova, G B; Atanasov, P A

    2012-03-31

    Thin ZnO nanostructured films were produced by pulsed laser deposition (PLD) for surface enhanced Raman spectroscopy (SERS) studies. The experimental conditions used for preparation of the samples were chosen to obtain different types of ZnO nanostructures. The Raman spectra of rhodamine 6G (R6G) were measured at an excitation wavelength of 785 nm after coating the ZnO nanostructures with a thin Au layer. The influence of the surface morphology on the Raman signal obtained from the samples was investigated. High SERS signal enhancement was observed from all Au-coated ZnO nanostructures.

  17. Direct Cross-Linking of Au/Ag Alloy Nanoparticles into Monolithic Aerogels for Application in Surface-Enhanced Raman Scattering.

    PubMed

    Gao, Xiaonan; Esteves, Richard J Alan; Nahar, Lamia; Nowaczyk, Jordan; Arachchige, Indika U

    2016-05-25

    The direct cross-linking of Au/Ag alloy nanoparticles (NPs) into high surface area, mesoporous Au/Ag aerogels via chemical oxidation of the surface ligands is reported. The precursor alloy NPs with composition-tunable morphologies were produced by galvanic replacement of the preformed Ag hollow NPs. The effect of Au:Ag molar ratio on the NP morphology and surface plasmon resonance has been thoroughly investigated and resulted in smaller Au/Ag alloy NPs (4-8 nm), larger Au/Ag alloy hollow NPs (40-45 nm), and Au/Ag alloy hollow particles decorated with smaller Au NPs (2-5 nm). The oxidative removal of surfactant ligands, followed by supercritical drying, is utilized to construct large (centimeter to millimeter) self-supported Au/Ag alloy aerogels. The resultant assemblies exhibit high surface areas (67-73 m(2)/g), extremely low densities (0.051-0.055 g/cm(3)), and interconnected mesoporous (2-50 nm) networks, making them of great interest for a number of new technologies. The influence of mesoporous gel morphology on surface-enhanced Raman scattering (SERS) has been studied using Rhodamine 101 (Rd 101) as the probe molecule. The alloy aerogels exhibit SERS signal intensities that are 10-42 times higher than those achieved from the precursor Au/Ag alloy NPs. The Au/Ag alloy aerogel III exhibits SERS sensing capability down to 1 nM level. The increased signal intensities attained for alloy aerogels are attributed to highly porous gel morphology and enhanced surface roughness that can potentially generate a large number of plasmonic hot spots, creating efficient SERS substrates for future applications. PMID:27142886

  18. Approximate treatment of semicore states in GW calculations with application to Au clusters

    SciTech Connect

    Xian, Jiawei; Baroni, Stefano; Umari, P.

    2014-03-28

    We address the treatment of transition metal atoms in GW electronic-structure calculations within the plane-wave pseudo-potential formalism. The contributions of s and p semi-core electrons to the self-energy, which are essential to grant an acceptable accuracy, are dealt with using a recently proposed scheme whereby the exchange components are treated exactly at the G{sub 0}W{sub 0} level, whereas a suitable approximation to the correlation components is devised. This scheme is benchmarked for small gold nano-clusters, resulting in ionization potentials, electron affinities, and density of states in very good agreement with those obtained from calculations where s and p semicore states are treated as valence orbitals, and allowing us to apply this same scheme to clusters of intermediate size, Au{sub 20} and Au{sub 32}, that would be otherwise very difficult to deal with.

  19. Highly narrow nanogap-containing Au@Au core-shell SERS nanoparticles: size-dependent Raman enhancement and applications in cancer cell imaging.

    PubMed

    Hu, Chongya; Shen, Jianlei; Yan, Juan; Zhong, Jian; Qin, Weiwei; Liu, Rui; Aldalbahi, Ali; Zuo, Xiaolei; Song, Shiping; Fan, Chunhai; He, Dannong

    2016-01-28

    Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (∼15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (∼1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (∼76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection. PMID:26701141

  20. ZnO/Au-based surface plasmon resonance for CO2 gas sensing application

    NASA Astrophysics Data System (ADS)

    Nuryadi, Ratno; Mayasari, Rina Dewi

    2016-01-01

    We fabricate surface plasmon resonance (SPR) device using a modified ZnO/Au-Kretschmann configuration to investigate the possibility of using ZnO for CO2 gas sensing at room temperature. Here, nanostructured ZnO/Au layer was deposited on the flat surface of the prism and then gas chamber was placed on the ZnO/Au surface to observe the gas response. The ZnO structures were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy. We found that ZnO structures have two types of nanostructures, i.e., individual nanorods and flower-like structures, which have hexagonal crystal structure. The ZnO nanorod has a diameter ranged from 200 to 300 nm and length ranged from 3 to 5 μm. The effect of gas response is demonstrated by a shift of SPR spectra and a change in light reflectance. It is found that the adsorption of gas molecules on the ZnO nanorods produces the shift of SPR angle to the lower light incident angle. A consistent sensing behavior over repetitive circles is also demonstrated.

  1. Electrogenerated Chemiluminescence Behavior of Au nanoparticles-hybridized Pb (II) metal-organic framework and its application in selective sensing hexavalent chromium.

    PubMed

    Ma, Hongmin; Li, Xiaojian; Yan, Tao; Li, Yan; Liu, Haiyang; Zhang, Yong; Wu, Dan; Du, Bin; Wei, Qin

    2016-01-01

    In this work, a novel electrochemiluminescence (ECL) sensor based on Au nanoparticles-hybridized Pb (II)-β-cyclodextrin (Pb-β-CD) metal-organic framework for detecting hexavalent chromium (Cr(VI)) was developed. Pb-β-CD shows excellent ECL behavior and unexpected reducing ability towards Au ions. Au nanoparticles could massively form on the surface of Pb-β-CD (Au@Pb-β-CD) without use of any additional reducing agent. In the presence of coreactant K2S2O8, the ECL emission of Pb-β-CD was enhanced by the formation of Au nanoparticles. Cr(VI) can collisionally quench the ECL behavior of Au@Pb-β-CD/S2O8(2-) system and the detection mechanism was investigated. This ECL sensor is found to have a linear response in the range of 0.01-100 μM and a low detection limit of 3.43 nM (S/N = 3) under the optimal conditions. These results suggest that metal-organic framework Au@Pb-β-CD has great potential in extending the application in the ECL field as an efficient luminophore. PMID:26902375

  2. Electrogenerated Chemiluminescence Behavior of Au nanoparticles-hybridized Pb (II) metal-organic framework and its application in selective sensing hexavalent chromium

    PubMed Central

    Ma, Hongmin; Li, Xiaojian; Yan, Tao; Li, Yan; Liu, Haiyang; Zhang, Yong; Wu, Dan; Du, Bin; Wei, Qin

    2016-01-01

    In this work, a novel electrochemiluminescence (ECL) sensor based on Au nanoparticles-hybridized Pb (II)-β-cyclodextrin (Pb-β-CD) metal-organic framework for detecting hexavalent chromium (Cr(VI)) was developed. Pb-β-CD shows excellent ECL behavior and unexpected reducing ability towards Au ions. Au nanoparticles could massively form on the surface of Pb-β-CD (Au@Pb-β-CD) without use of any additional reducing agent. In the presence of coreactant K2S2O8, the ECL emission of Pb-β-CD was enhanced by the formation of Au nanoparticles. Cr(VI) can collisionally quench the ECL behavior of Au@Pb-β-CD/S2O82− system and the detection mechanism was investigated. This ECL sensor is found to have a linear response in the range of 0.01–100 μM and a low detection limit of 3.43 nM (S/N = 3) under the optimal conditions. These results suggest that metal-organic framework Au@Pb-β-CD has great potential in extending the application in the ECL field as an efficient luminophore. PMID:26902375

  3. REFLECT: Logiciel de restitution des reflectances au sol pour l'amelioration de la qualite de l'information extraite des images satellitales a haute resolution spatiale

    NASA Astrophysics Data System (ADS)

    Bouroubi, Mohamed Yacine

    Multi-spectral satellite imagery, especially at high spatial resolution (finer than 30 m on the ground), represents an invaluable source of information for decision making in various domains in connection with natural resources management, environment preservation or urban planning and management. The mapping scales may range from local (finer resolution than 5 m) to regional (resolution coarser than 5m). The images are characterized by objects reflectance in the electromagnetic spectrum witch represents the key information in many applications. However, satellite sensor measurements are also affected by parasite input due to illumination and observation conditions, to the atmosphere, to topography and to sensor properties. Two questions have oriented this research. What is the best approach to retrieve surface reflectance with the measured values while taking into account these parasite factors? Is this retrieval a sine qua non condition for reliable image information extraction for the diverse domains of application for the images (mapping, environmental monitoring, landscape change detection, resources inventory, etc.)? The goals we have delineated for this research are as follow: (1) Develop software to retrieve ground reflectance while taking into account the aspects mentioned earlier. This software had to be modular enough to allow improvement and adaptation to diverse remote sensing application problems; and (2) Apply this software in various context (urban, agricultural, forest) and analyse results to evaluate the accuracy gain of extracted information from remote sensing imagery transformed in ground reflectance images to demonstrate the necessity of operating in this way, whatever the type of application. During this research, we have developed a tool to retrieve ground reflectance (the new version of the REFLECT software). This software is based on the formulas (and routines) of the 6S code (Second Simulation of Satellite Signal in the Solar Spectrum

  4. Study of the nucleation and growth of antibiotic labeled Au NPs and blue luminescent Au8 quantum clusters for Hg2+ ion sensing, cellular imaging and antibacterial applications

    NASA Astrophysics Data System (ADS)

    Khandelwal, Puneet; Singh, Dheeraj K.; Sadhu, Subha; Poddar, Pankaj

    2015-11-01

    Herein, we report a detailed experimental study supported by DFT calculations to understand the mechanism behind the synthesis of cefradine (CFD - an antibiotic) labeled gold nanoparticles (Au NPs) by employing CFD as both a mild reducing and capping agent. The analysis of the effect of growth conditions reveals that a higher concentration of HAuCl4 results in the formation of an increasing fraction of anisotropic structures, higher temperature leads to the formation of quasi-spherical particles instead of anisotropic ones, and larger pH leads to the formation of much smaller particles. The cyclic voltammetry (CV) results show that when the pH of the reaction medium increases from 4 to 6, the reduction potential of CFD increases which leads to the synthesis of nanoparticles (in a pH 4 reaction) to quantum clusters (in a pH 6 reaction). The MALDI-TOF mass spectrometry results of supernatant of the pH 6 reaction indicate the formation of [Au8(CFD)2S6] QCs which show fluorescence at ca. 432 nm with a Stokes shift of ca. 95 nm. The blue luminescence from Au8 QCs was applied for sensing of Hg2+ ions on the basis of an aggregation-induced fluorescence quenching mechanism and offers good selectivity and a high sensitivity with a limit of detection ca. 2 nM which is lower than the detection requirement of 10 nM by the U.S. EPA and 30 nM by WHO for drinking water. We have also applied the sensing probe to detect Hg2+ ions in bacterial samples. Further, we have investigated the antibacterial property of as-synthesized Au NPs using MIC, growth curve and cell survival assay. The results show that Au NPs could reduce the cell survival very efficiently rather than the cell growth in comparison to the antibiotic itself. The scanning electron microscopy study shows the degradation and blebbing of the bacterial cell wall upon exposure with Au NPs which was further supported by fluorescence microscopy results. These Au NPs did not show reactive oxygen species generation. We believe

  5. Optical properties of random alloys: application to CuAu and NiPt

    NASA Astrophysics Data System (ADS)

    Krishna Saha, Kamal; Mookerjee, Abhijit

    2005-07-01

    In an earlier paper we presented a formulation for the calculation of the configuration-averaged optical conductivity in random alloys. Our formulation is based on the augmented-space theorem introduced by one of us (Mookerjee 1973 J. Phys. C: Solid State Phys. 6 1340). In this communication we shall combine the augmented space methodology with the tight-binding linear muffin-tin orbital technique (TB-LMTO) to study the optical conductivities of two alloys, CuAu and NiPt.

  6. Highly narrow nanogap-containing Au@Au core-shell SERS nanoparticles: size-dependent Raman enhancement and applications in cancer cell imaging

    NASA Astrophysics Data System (ADS)

    Hu, Chongya; Shen, Jianlei; Yan, Juan; Zhong, Jian; Qin, Weiwei; Liu, Rui; Aldalbahi, Ali; Zuo, Xiaolei; Song, Shiping; Fan, Chunhai; He, Dannong

    2016-01-01

    Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (~15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (~1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (~76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection.Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on

  7. Hybridized doxorubicin-Au nanospheres exhibit enhanced near-infrared surface plasmon absorption for photothermal therapy applications.

    PubMed

    Zhou, Jialin; Wang, Zuhua; Li, Qingpo; Liu, Fei; Du, Yongzhong; Yuan, Hong; Hu, Fuqiang; Wei, Yinghui; You, Jian

    2015-03-19

    Photothermal therapy (PTT) employs photosensitizing agents, which are taken up by cells and generate heat when irradiated with near-infrared (NIR) light, to enable the photoablation of cancer cells. High absorption in the NIR region is crucial for a photosensitizing agent to achieve efficient PTT. Different combinations between gold nanoparticles and fluorescent agents always influence their spectrum properties. Herein, we fabricated a novel combination of a fluorescent agent (doxorubicin, DOX, also a popular chemotherapeutic agent) with gold nanospheres by synthesizing hybridized DOX-Au nanospheres (DAuNS), where a part of the DOX molecules and Au co-formed a hybridized matrix as the shell and the remaining DOX molecules precipitated as the core. The unique structure of DAuNS induced interesting changes in the characteristics including spectrum properties, morphology, drug loading and antitumor activity. We observed that DAuNS exhibited a significantly enhanced surface plasmon absorption in the NIR region, inducing a more efficient photothermal conversion and stronger tumor-cell killing ability under NIR laser irradiation. In addition, our study presents a new and simple platform to load a drug into nanoparticles. DAuNS could be a promising nanoparticle with the "two punch" efficacy of PTT and chemotherapy and could be used in clinical applications due to its controllable synthesis, small size, and narrow size distribution. PMID:25757809

  8. Cu2O and Au/Cu2O particles: surface properties and applications in glucose sensing.

    PubMed

    Won, Yu-Ho; Stanciu, Lia A

    2012-01-01

    In this work we investigated the surface and facet-dependent catalytic properties of metal oxide particles as well as noble metal/metal oxide heterogeneous structures, with cuprous oxide (Cu(2)O) and Au/Cu(2)O being selected as model systems. As an example of application, we explored the potential of these materials in developing electrocatalytic devices. Cu(2)O particles were synthesized in various shapes, then used for testing their morphology-dependent electrochemical properties applied to the detection of glucose. While we did not attempt to obtain the best detection limit reported to date, the octahedral and hexapod Cu(2)O particles showed reasonable detection limits of 0.51 and 0.60 mM, respectively, which are physiologically relevant concentrations. However, detection limit seems to be less affected by particle shapes than sensitivity. Heterogeneous systems where Au NPs were deposited on the surface of Cu(2)O particles were also tested with similar results in terms of the effect of surface orientation. PMID:23201983

  9. Cu2O and Au/Cu2O Particles: Surface Properties and Applications in Glucose Sensing

    PubMed Central

    Won, Yu-Ho; Stanciu, Lia A.

    2012-01-01

    In this work we investigated the surface and facet-dependent catalytic properties of metal oxide particles as well as noble metal/metal oxide heterogeneous structures, with cuprous oxide (Cu2O) and Au/Cu2O being selected as model systems. As an example of application, we explored the potential of these materials in developing electrocatalytic devices. Cu2O particles were synthesized in various shapes, then used for testing their morphology-dependent electrochemical properties applied to the detection of glucose. While we did not attempt to obtain the best detection limit reported to date, the octahedral and hexapod Cu2O particles showed reasonable detection limits of 0.51 and 0.60 mM, respectively, which are physiologically relevant concentrations. However, detection limit seems to be less affected by particle shapes than sensitivity. Heterogeneous systems where Au NPs were deposited on the surface of Cu2O particles were also tested with similar results in terms of the effect of surface orientation. PMID:23201983

  10. Novel electrochemical redox-active species: one-step synthesis of polyaniline derivative-Au/Pd and its application for multiplexed immunoassay

    NASA Astrophysics Data System (ADS)

    Wang, Liyuan; Feng, Feng; Ma, Zhanfang

    2015-11-01

    Electrochemical redox-active species play crucial role in electrochemically multiplexed immunoassays. A one-pot method for synthesizing four kinds of new electrochemical redox-active species was reported using HAuCl4 and Na2PdCl4 as dual oxidating agents and aniline derivatives as monomers. The synthesized polyaniline derivative-Au/Pd composites, namely poly(N-methyl-o-benzenediamine)-Au/Pd, poly(N-phenyl-o-phenylenediamine)-Au/Pd, poly(N-phenyl-p-phenylenediamine)-Au/Pd and poly(3,3’,5,5’-tetramethylbenzidine)-Au/Pd, exhibited electrochemical redox activity at -0.65 V, -0.3 V, 0.12 V, and 0.5 V, respectively. Meanwhile, these composites showed high H2O2 electrocatalytic activity because of the presence of Au/Pd. The as-prepared composites were used as electrochemical immunoprobes in simultaneous detection of four tumor biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA199), carbohydrate antigen 72-4 (CA724), and alpha fetoprotein (AFP)). This immunoassay shed light on potential applications in simultaneous gastric cancer (related biomarkers: CEA, CA199, CA724) and liver cancer diagnosis (related biomarkers: CEA, CA199, AFP). The present strategy to the synthesize redox species could be easily extended to other polymers such as polypyrrole derivatives and polythiophene derivatives. This would be of great significance in the electrochemical detection of more analytes.

  11. Novel electrochemical redox-active species: one-step synthesis of polyaniline derivative-Au/Pd and its application for multiplexed immunoassay

    PubMed Central

    Wang, Liyuan; Feng, Feng; Ma, Zhanfang

    2015-01-01

    Electrochemical redox-active species play crucial role in electrochemically multiplexed immunoassays. A one-pot method for synthesizing four kinds of new electrochemical redox-active species was reported using HAuCl4 and Na2PdCl4 as dual oxidating agents and aniline derivatives as monomers. The synthesized polyaniline derivative-Au/Pd composites, namely poly(N-methyl-o-benzenediamine)-Au/Pd, poly(N-phenyl-o-phenylenediamine)-Au/Pd, poly(N-phenyl-p-phenylenediamine)-Au/Pd and poly(3,3’,5,5’-tetramethylbenzidine)-Au/Pd, exhibited electrochemical redox activity at −0.65 V, −0.3 V, 0.12 V, and 0.5 V, respectively. Meanwhile, these composites showed high H2O2 electrocatalytic activity because of the presence of Au/Pd. The as-prepared composites were used as electrochemical immunoprobes in simultaneous detection of four tumor biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA199), carbohydrate antigen 72-4 (CA724), and alpha fetoprotein (AFP)). This immunoassay shed light on potential applications in simultaneous gastric cancer (related biomarkers: CEA, CA199, CA724) and liver cancer diagnosis (related biomarkers: CEA, CA199, AFP). The present strategy to the synthesize redox species could be easily extended to other polymers such as polypyrrole derivatives and polythiophene derivatives. This would be of great significance in the electrochemical detection of more analytes. PMID:26577799

  12. Crystallographic investigation of Au nanoparticles embedded in a SrTiO{sub 3} thin film for plasmonics applications by means of synchrotron radiation

    SciTech Connect

    Pincini, Davide; Mazzoli, Claudio; Bernhardt, Hendrik; Katzer, Christian; Schmidl, Frank; Uschmann, Ingo; Detlefs, Carsten

    2015-03-14

    Self-organized monocrystalline Au nanoparticles with potential applications in plasmonics are grown in a SrTiO{sub 3} matrix by a novel two-step deposition process. The crystalline preferred orientation of these Au nanoparticles is investigated by synchrotron hard x-ray diffraction. Nanoparticles preferentially align with the (111) direction along the substrate normal (001), whereas two in-plane orientations are found with [110]{sub SrTiO{sub 3}}∥[110]{sub Au} and [100]{sub SrTiO{sub 3}}∥[110]{sub Au}. Additionally, a smaller diffraction signal from nanoparticles with the (001) direction parallel to the substrate normal (001) is observed; once again, two in-plane orientations are found, with [100]{sub SrTiO{sub 3}}∥[100]{sub Au} and [100]{sub SrTiO{sub 3}}∥[110]{sub Au}. The populations of the two in-plane orientations are found to depend on the thickness of the gold film deposited in the first step of the growth.

  13. Facile Synthesis of Au-Coated Magnetic Nanoparticles and Their Application in Bacteria Detection via a SERS Method.

    PubMed

    Wang, Junfeng; Wu, Xuezhong; Wang, Chongwen; Rong, Zhen; Ding, Hongmei; Li, Hui; Li, Shaohua; Shao, Ningsheng; Dong, Peitao; Xiao, Rui; Wang, Shengqi

    2016-08-10

    This study proposes a facile method for synthesis of Au-coated magnetic nanoparticles (AuMNPs) core/shell nanocomposites with nanoscale rough surfaces. MnFe2O4 nanoparticles (NPs) were first modified with a uniform polyethylenimine layer (2 nm) through self-assembly under sonication. The negatively charged Au seeds were then adsorbed on the surface of the MnFe2O4 NPs through electrostatic interaction for Au shell formation. Our newly developed sonochemically assisted hydroxylamine seeding growth method was used to grow the adsorbed gold seeds into large Au nanoparticles (AuNPs) to form a nanoscale rough Au shell. Au-coated magnetic nanoparticles (AuMNPs) were obtained from the intermediate product (Au seeds decorated magnetic core) under sonication within 5 min. The AuMNPs were highly uniform in size and shape and exhibited satisfactory surface-enhanced Raman scattering (SERS) activity and strong magnetic responsivity. PATP was used as a probe molecule to evaluate the SERS performance of the synthesized AuMNPs with a detection limit of 10(-9) M. The synthesized AuMNPs were conjugated with Staphylococcus aureus (S. aureus) antibody for bacteria capture and separation. The synthesized plasmonic AuNR-DTNB NPs, whose LSPR wavelength was adjusted to the given laser excitation wavelength (785 nm), were conjugated with S. aureus antibody to form a SERS tag for specific recognition and report of the target bacteria. S. aureus was indirectly detected through SERS based on sandwich-structured immunoassay, with a detection limit of 10 cells/mL. Moreover, the SERS intensity at Raman peak of 1331 cm(-1) exhibited a linear relationship to the logarithm of bacteria concentrations ranging from 10(1) cells/mL to 10(5) cells/mL. PMID:27420923

  14. Design of highly sensitive and selective Au@NiO yolk-shell nanoreactors for gas sensor applications.

    PubMed

    Rai, Prabhakar; Yoon, Ji-Wook; Jeong, Hyun-Mook; Hwang, Su-Jin; Kwak, Chang-Hoon; Lee, Jong-Heun

    2014-07-21

    Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H₂S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH₃, CO and H₂). The maximum response was 108.92 for 5 ppm of H₂S gas at 300 °C, which was approximately 19 times higher than that for the interfering gases. The response of Au@NiO yolk-shell NPs to H₂S was approximately 4 times higher than that of bare NiO hollow nanospheres. Improved performance of Au@NiO yolk-shell NPs was attributed to hollow spaces that allowed the accessibility of Au NPs to gas molecules. It was suggested that adsorption of H₂S on Au NPs resulted in the formation of sulfide layer, which possibly lowered its work function, and therefore tuned the electron transfer from Au to NiO rather NiO to Au, which leaded to increase in resistance and therefore response. PMID:24933405

  15. Hybridized doxorubicin-Au nanospheres exhibit enhanced near-infrared surface plasmon absorption for photothermal therapy applications

    NASA Astrophysics Data System (ADS)

    Zhou, Jialin; Wang, Zuhua; Li, Qingpo; Liu, Fei; Du, Yongzhong; Yuan, Hong; Hu, Fuqiang; Wei, Yinghui; You, Jian

    2015-03-01

    Photothermal therapy (PTT) employs photosensitizing agents, which are taken up by cells and generate heat when irradiated with near-infrared (NIR) light, to enable the photoablation of cancer cells. High absorption in the NIR region is crucial for a photosensitizing agent to achieve efficient PTT. Different combinations between gold nanoparticles and fluorescent agents always influence their spectrum properties. Herein, we fabricated a novel combination of a fluorescent agent (doxorubicin, DOX, also a popular chemotherapeutic agent) with gold nanospheres by synthesizing hybridized DOX-Au nanospheres (DAuNS), where a part of the DOX molecules and Au co-formed a hybridized matrix as the shell and the remaining DOX molecules precipitated as the core. The unique structure of DAuNS induced interesting changes in the characteristics including spectrum properties, morphology, drug loading and antitumor activity. We observed that DAuNS exhibited a significantly enhanced surface plasmon absorption in the NIR region, inducing a more efficient photothermal conversion and stronger tumor-cell killing ability under NIR laser irradiation. In addition, our study presents a new and simple platform to load a drug into nanoparticles. DAuNS could be a promising nanoparticle with the ``two punch'' efficacy of PTT and chemotherapy and could be used in clinical applications due to its controllable synthesis, small size, and narrow size distribution.Photothermal therapy (PTT) employs photosensitizing agents, which are taken up by cells and generate heat when irradiated with near-infrared (NIR) light, to enable the photoablation of cancer cells. High absorption in the NIR region is crucial for a photosensitizing agent to achieve efficient PTT. Different combinations between gold nanoparticles and fluorescent agents always influence their spectrum properties. Herein, we fabricated a novel combination of a fluorescent agent (doxorubicin, DOX, also a popular chemotherapeutic agent) with gold

  16. Formation of core-shell Au@Ag nanorods induced by catecholamines: A comparative study and an analytical application.

    PubMed

    Gorbunova, M V; Apyari, V V; Dmitrienko, S G; Garshev, A V

    2016-09-14

    Gold nanorods (AuNRs) stabilized by cetyltrimethylammonium bromide (CTAB) were synthesized and an interaction of catecholamines (CAs) with silver ions in the presence of the obtained AuNRs was studied. The reaction results into formation of core-shell Au@Ag nanorods (Au@AgNRs) and leads to a hypsochromic shift of the long-wave surface plasmon resonance (SPR) band in the absorption spectrum of AuNRs. The influence of a CA structure, excess of CTAB, interaction time, pH, concentration of AuNRs, silver ions and CAs on this interaction was studied. Based on correlation of the NRs spectral characteristics with the concentration of CAs, a method for spectrophotometric determination of dobutamine, epinephrine, norepinephrine and dopamine with detection limits 27, 18, 16 and 13 μg L(-1), respectively, has been developed. The method can be applied to the analysis of medicines. PMID:27566354

  17. Rapid synthesis and characterization of hybrid ZnO@Au core-shell nanorods for high performance, low temperature NO2 gas sensor applications

    NASA Astrophysics Data System (ADS)

    Ponnuvelu, Dinesh Veeran; Pullithadathil, Biji; Prasad, Arun K.; Dhara, Sandip; Ashok, Anuradha; Mohamed, Kamruddin; Tyagi, Ashok Kumar; Raj, Baldev

    2015-11-01

    A rapid synthesis route for hybrid ZnO@Au core-shell nanorods has been realized for ultrasensitive, trace-level NO2 gas sensor applications. ZnO nanorods and hybrid ZnO@Au core-shell nanorods are structurally analyzed using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Optical characterization using UV-visible (UV-vis), photoluminescence (PL) and Raman spectroscopies elucidate alteration in the percentage of defect and charge transport properties of ZnO@Au core-shell nanorods. The study reveals the accumulation of electrons at metal-semiconductor junctions leading to upward band bending for ZnO and thus favors direct electron transfer from ZnO to Au nanoclusters, which mitigates charge carrier recombination process. The operating temperature of ZnO@Au core-shell nanorods based sensor significantly decreased to 150 °C compared to alternate NO2 sensors (300 °C). Moreover, a linear sensor response in the range of 0.5-5 ppm of NO2 concentration was observed with a lowest detection limit of 500 ppb using conventional electrodes. The defects with deep level, observed in ZnO nanorods and hybrid ZnO@Au core-shell nanorods influences local electron density, which in-turn indirectly influence the gas sensing properties. The ZnO@Au core-shell nanorods based sensor exhibited good selectivity toward NO2 and was found to be very stable.

  18. Qualitative analysis of a generalized Maxwell-Einstein system - Application for a cosmological model

    NASA Astrophysics Data System (ADS)

    Tossa, Joel; Fabris, Julo C.; Romero, Carlos

    1992-02-01

    A methodology for studying dynamical systems is employed to qualitatively analyze the relationship between a Maxwellian field coupled to gravity and Einstein equations. The Maxwellian-type field is assumed to have n even dimensions to develop variables describing the expansion factor of the 4D universe and the variation of the gravitational constant. The resulting phase diagram is analyzed and found to have trajectories expanding from a singularity at infinity and tending toward equilibrium. This description of Minkowskian space-time is complemented by nonphysical regions in which trajectories originating from a 'big-bang' singularity tend toward an unstable singularity at infinity.

  19. Graphene decorated with PtAu alloy nanoparticles: facile synthesis and promising application for formic acid oxidation

    SciTech Connect

    Zhang, Sheng; Shao, Yuyan; Liao, Honggang; Liu, Jun; Aksay, Ilhan A.; Yin, Geping; Lin, Yuehe

    2011-03-01

    PtAu alloy nanoparticles (~ 3.2 nm in diameter) are synthesized in poly(diallyldimethylammonium chloride) (PDDA) aqueous solution and uniformly dispersed on graphene nanosheets. PtAu/graphene exhibits high electrocatalytic activity and stability for formic acid oxidation, which is attributed to the high dispersion of PtAu nanoparticles and the specific interaction between PtAu and graphene, indicating a promising catalyst for direct formic acid fuel cells. The facile method can be readily extended to the synthesis of other alloy nanoparticles.

  20. Fabrication of hierarchical core-shell Au@ZnO heteroarchitectures initiated by heteroseed assembly for photocatalytic applications.

    PubMed

    Qin, Yao; Zhou, Yanjie; Li, Jie; Ma, Jie; Shi, Donglu; Chen, Junhong; Yang, Jinhu

    2014-03-15

    Three dimensional dandelion-like hierarchical core-shell Au@ZnO heteroarchitectures with ZnO nanorods grown radially on Au nanoparticle (NP) cores have been successfully prepared with a high yield via a simple solution method involving heteroseed-induced nucleation and subsequent heteroepitaxial growth processes. Briefly, mercaptopropionic acid (MA) modified Au NPs were synthesized beforehand and served as nucleation centers for primary ZnO seed generation and Au@ZnO heteroseed formation. Then an epitaxial growth of ZnO nanorods (ZnO NRs) on the Au@ZnO heteroseeds resulted in the formation of Au@ZnO dandelions. The photocatalytic properties of as-prepared Au@ZnO dandelions were evaluated through rhodamine B (RhB) photodegradation under UV irradiation. The result showed that the Au@ZnO dandelions had improved photocatalytic performance compared with pure ZnO NRs and hybrids of ZnO NRs/Au NPs, due likely to the synergistic effect of the metal-semiconductor heterojunction and the unique dandelion-like hierarchical core-shell structure. PMID:24461832

  1. Quantitative and qualitative research across cultures and languages: cultural metrics and their application.

    PubMed

    Wagner, Wolfgang; Hansen, Karolina; Kronberger, Nicole

    2014-12-01

    Growing globalisation of the world draws attention to cultural differences between people from different countries or from different cultures within the countries. Notwithstanding the diversity of people's worldviews, current cross-cultural research still faces the challenge of how to avoid ethnocentrism; comparing Western-driven phenomena with like variables across countries without checking their conceptual equivalence clearly is highly problematic. In the present article we argue that simple comparison of measurements (in the quantitative domain) or of semantic interpretations (in the qualitative domain) across cultures easily leads to inadequate results. Questionnaire items or text produced in interviews or via open-ended questions have culturally laden meanings and cannot be mapped onto the same semantic metric. We call the culture-specific space and relationship between variables or meanings a 'cultural metric', that is a set of notions that are inter-related and that mutually specify each other's meaning. We illustrate the problems and their possible solutions with examples from quantitative and qualitative research. The suggested methods allow to respect the semantic space of notions in cultures and language groups and the resulting similarities or differences between cultures can be better understood and interpreted. PMID:24809790

  2. The effect of Alexander technique training program: A qualitative study of ordinary behavior application.

    PubMed

    Kim, Soo-Yeon; Baek, Soon Gi

    2014-12-01

    The purpose of this study was to configure and apply the Alexander technique training program and assess the effect of program through physical, emotional and behavioral aspects. To achieve the research aims, qualitative research method had been conducted, subjecting 8 people, who were participating in Alexander Technique training program for this study. The study used focus group interview method for collecting date and employed for the interview method by mixing the semi-structured and unstructured questionnaire. The results were followings. First, one could develop body awareness and body consciousness through experiencing lived bodily sensation. Second, from Alexander Technique training program, people experienced psycho & physical's equilibrium. Third, one could change not only the manner of use of body but also the attitude to the life from conscious attention to daily ordinary movement. The results provided empirical evidence of Alexander Technique training program's functions in terms of physical, emotional and behavioral aspect through the process of consciousness control from lived body education. PMID:25610819

  3. Design of highly sensitive and selective Au@NiO yolk-shell nanoreactors for gas sensor applications

    NASA Astrophysics Data System (ADS)

    Rai, Prabhakar; Yoon, Ji-Wook; Jeong, Hyun-Mook; Hwang, Su-Jin; Kwak, Chang-Hoon; Lee, Jong-Heun

    2014-06-01

    Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H2S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH3, CO and H2). The maximum response was 108.92 for 5 ppm of H2S gas at 300 °C, which was approximately 19 times higher than that for the interfering gases. The response of Au@NiO yolk-shell NPs to H2S was approximately 4 times higher than that of bare NiO hollow nanospheres. Improved performance of Au@NiO yolk-shell NPs was attributed to hollow spaces that allowed the accessibility of Au NPs to gas molecules. It was suggested that adsorption of H2S on Au NPs resulted in the formation of sulfide layer, which possibly lowered its work function, and therefore tuned the electron transfer from Au to NiO rather NiO to Au, which leaded to increase in resistance and therefore response.Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H2S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH3, CO and H2). The maximum response was 108.92 for 5 ppm

  4. Naphthalimide derived fluorescent probes with turn-on response for Au(3+) and the application for biological visualization.

    PubMed

    Li, Yan; Qiu, Yanxin; Zhang, Jianjian; Zhu, Xinyue; Zhu, Bin; Liu, Xiaoyan; Zhang, Xiaoyu; Zhang, Haixia

    2016-09-15

    The 4-N,N-dimethyl-1,8-naphthalimide based fluorescent probes have been explored for selective detection of Au(3+). Both probes show a pronounced fluorescence enhancement response to Au(3+). Hydroxy is introduced as ligand of Au(3+) for Probe 1 and the newly designed Probe 2 contains an alkyne moiety to recognize Au(3+) through an irreversible C≡C bond hydrolysis reaction. Probe 1 exhibits higher performance such as faster response, lower detection limit of 0.050μM and the better responsive effect in 99.5% water system compared with most of probes published. The Probe 2 displays high stability to pH, suitable water solubility, wider linear range (0-100μM) to Au(3+), and live-cells imaging with low cytotoxicity. PMID:27135938

  5. Synthesis and characterization of Cu2O/Au and its application in catalytic reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Guo, X. H.; Ma, J. Q.; Ge, H. G.

    2015-08-01

    Monodispersed Cu2O spherical colloids with diameter of about 300 nm were prepared by a facile additive-assisted complex-precursor solution method. Core-shell structure Cu2O/Au composites, constructed by spherical Cu2O core and Au nanoparticles shell, were obtained via galvanic replacement method. The morphology, microstructure and optical properties of the Cu2O/Au composites were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectra and ultraviolet-visible absorption. The results showed that Au NPs with an average size of 12 nm were uniformly distributed on the surface of the Cu2O spheres with size about 300 nm. Cu2O/Au composites exhibit high catalytic activity toward 4-NP reduction at room temperature.

  6. Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe3O4 nanocomposites as a promising, nontoxic system for biomedical applications

    PubMed Central

    Kashanian, Soheila

    2015-01-01

    Summary The unique properties and applications of iron oxide and Au nanoparticles have motivated researchers to synthesize and optimize a combined nanocomposite containing both. By using various polymers such as chitosan, some of the problems of classic core–shell structures (such as reduced saturation magnetization and thick coating) have been overcome. In the present study, chitosan and one of its well-known derivatives, N-trimethylchitosan (TMC), were applied to construct three-layer nanocomposites in an Au/polymer/Fe3O4 system. It was demonstrated that replacement of chitosan with TMC reasonably improved the properties of the final nanocomposites including their size, magnetic behavior and thermal stability. Moreover, the results of the MTT assay showed no significant cytotoxicity effect when the Au/TMC/Fe3O4 nanocomposites were applied in vitro. These TMC-containing magnetic nanoparticles are well-coated by Au nanoparticles and have good biocompatibility and can thus play the role of a platform or a label in various fields of application, especially the biomedical sciences and biosensors. PMID:26425418

  7. The effect of Alexander technique training program: A qualitative study of ordinary behavior application

    PubMed Central

    Kim, Soo-Yeon; Baek, Soon Gi

    2014-01-01

    The purpose of this study was to configure and apply the Alexander technique training program and assess the effect of program through physical, emotional and behavioral aspects. To achieve the research aims, qualitative research method had been conducted, subjecting 8 people, who were participating in Alexander Technique training program for this study. The study used focus group interview method for collecting date and employed for the interview method by mixing the semi-structured and unstructured questionnaire. The results were followings. First, one could develop body awareness and body consciousness through experiencing lived bodily sensation. Second, from Alexander Technique training program, people experienced psycho & physical’s equilibrium. Third, one could change not only the manner of use of body but also the attitude to the life from conscious attention to daily ordinary movement. The results provided empirical evidence of Alexander Technique training program’s functions in terms of physical, emotional and behavioral aspect through the process of consciousness control from lived body education. PMID:25610819

  8. Battery energy storage and superconducting magnetic energy storage for utility applications: A qualitative analysis

    SciTech Connect

    Akhil, A.A.; Butler, P.; Bickel, T.C.

    1993-11-01

    This report was prepared at the request of the US Department of Energy`s Office of Energy Management for an objective comparison of the merits of battery energy storage with superconducting magnetic energy storage technology for utility applications. Conclusions are drawn regarding the best match of each technology with these utility application requirements. Staff from the Utility Battery Storage Systems Program and the superconductivity Programs at Sandia National contributed to this effort.

  9. Can the caged bird sing? Reflections on the application of qualitative research methods to case study design in homeopathic medicine

    PubMed Central

    Thompson, Trevor DB

    2004-01-01

    Background Two main pathways exist for the development of knowledge in clinical homeopathy. These comprise clinical trials conducted primarily by university-based researchers and cases reports and homeopathic "provings" compiled by engaged homeopathic practitioners. In this paper the relative merits of these methods are examined and a middle way proposed. This consists of the "Formal Case Study" (FCS) in which qualitative methods are used to increase the rigour and sophistication with which homeopathic cases are studied. Before going into design issues this paper places the FCS in an historical and academic context and describes the relative merits of the method. Discussion Like any research, the FCS should have a clear focus. This focus can be both "internal", grounded in the discourse of homeopathy and also encompass issues of wider appeal. A selection of possible "internal" and "external" research questions is introduced. Data generation should be from multiple sources to ensure adequate triangulation. This could include the recording and transcription of actual consultations. Analysis is built around existing theory, involves cross-case comparison and the search for deviant cases. The trustworthiness of conclusions is ensured by the application of concepts from qualitative research including triangulation, groundedness, respondent validation and reflexivity. Though homeopathic case studies have been reported in mainstream literature, none has used formal qualitative methods – though some such studies are in progress. Summary This paper introduces the reader to a new strategy for homeopathic research. This strategy, termed the "formal case study", allows for a naturalistic enquiry into the players, processes and outcomes of homeopathic practice. Using ideas from qualitative research, it allows a rigorous approach to types of research question that cannot typically be addressed through clinical trials and numeric outcome studies. The FCS provides an opportunity

  10. Plethora or paucity: a systematic search and bibliometric study of the application and design of qualitative methods in nursing research 2008-2010.

    PubMed

    Ball, Elaine; McLoughlin, Moira; Darvill, Angela

    2011-04-01

    Qualitative methodology has increased in application and acceptability in all research disciplines. In nursing, it is appropriate that a plethora of qualitative methods can be found as nurses pose real-world questions to clinical, cultural and ethical issues of patient care (Johnson, 2007; Long and Johnson, 2007), yet the methods nurses readily use in pursuit of answers remains under intense scrutiny. One of the problems with qualitative methodology for nursing research is its place in the hierarchy of evidence (HOE); another is its comparison to the positivist constructs of what constitutes good research and the measurement of qualitative research against this. In order to position and strengthen its evidence base, nursing may well seek to distance itself from a qualitative perspective and utilise methods at the top of the HOE; yet given the relation of qualitative methods to nursing this would constrain rather than broaden the profession in search of answers and an evidence base. The comparison between qualitative and quantitative can be both mutually exclusive and rhetorical, by shifting the comparison this study takes a more reflexive position and critically appraises qualitative methods against the standards set by qualitative researchers. By comparing the design and application of qualitative methods in nursing over a two year period, the study examined how qualitative stands up to independent rather than comparative scrutiny. For the methods, a four-step mixed methods approach newly constructed by the first author was used to define the scope of the research question and develop inclusion criteria. 2. Synthesis tables were constructed to organise data, 3. Bibliometrics configured data. 4. Studies selected for inclusion in the review were critically appraised using a critical interpretive synthesis (Dixon-Woods et al., 2006). The paper outlines the research process as well as findings. Results showed of the 240 papers analysed, 27% used ad hoc or no

  11. Qualitative Research and Case Study Applications in Education. Revised and Expanded from "Case Study Research in Education."

    ERIC Educational Resources Information Center

    Merriam, Sharan B.

    This book offers a resource guide for qualitative researchers in education, discussing data collection techniques, data analysis, reporting, and the issues of validity, reliability, and ethics. Part 1 reviews the nature and design of qualitative research; it discusses various types of qualitative research (including case studies), and how to…

  12. DNA-templated synthesis of PtAu bimetallic nanoparticle/graphene nanocomposites and their application in glucose biosensor

    NASA Astrophysics Data System (ADS)

    Leng, Jing; Wang, Wen-Min; Lu, Li-Min; Bai, Ling; Qiu, Xin-Lan

    2014-02-01

    In this paper, single-stranded DNA (ss-DNA) is demonstrated to functionalize graphene (GR) and to further guide the growth of PtAu bimetallic nanoparticles (PtAuNPs) on GR with high densities and dispersion. The obtained nanocomposites (PtAuNPs/ss-DNA/GR) were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS), and electrochemical techniques. Then, an enzyme nanoassembly was prepared by self-assembling glucose oxidase (GOD) on PtAuNP/ss-DNA/GR nanocomposites (GOD/PtAuNPs/ss-DNA/GR). The nanocomposites provided a suitable microenvironment for GOD to retain its biological activity. The direct and reversible electron transfer process between the active site of GOD and the modified electrode was realized without any extra electron mediator. Thus, the prepared GOD/PtAuNP/ss-DNA/GR electrode was proposed as a biosensor for the quantification of glucose. The effects of pH, applied potential, and temperature on the performance of the biosensor were discussed in detail and were optimized. Under optimal conditions, the biosensor showed a linearity with glucose concentration in the range of 1.0 to 1,800 μM with a detection limit of 0.3 μM (S/N = 3). The results demonstrate that the developed approach provides a promising strategy to improve the sensitivity and enzyme activity of electrochemical biosensors.

  13. An enhanced photocatalytic response of nanometric TiO2 wrapping of Au nanoparticles for eco-friendly water applications

    NASA Astrophysics Data System (ADS)

    Scuderi, Viviana; Impellizzeri, Giuliana; Romano, Lucia; Scuderi, Mario; Brundo, Maria V.; Bergum, Kristin; Zimbone, Massimo; Sanz, Ruy; Buccheri, Maria A.; Simone, Francesca; Nicotra, Giuseppe; Svensson, Bengt G.; Grimaldi, Maria G.; Privitera, Vittorio

    2014-09-01

    We propose a ground-breaking approach by an upside-down vision of the Au/TiO2 nano-system in order to obtain an enhanced photocatalytic response. The system was synthesized by wrapping Au nanoparticles (~8 nm mean diameter) with a thin layer of TiO2 (~4 nm thick). The novel idea of embedding Au nanoparticles with titanium dioxide takes advantage of the presence of metal nanoparticles, in terms of electron trapping, without losing any of the TiO2 exposed surface, so as to favor the photocatalytic performance of titanium dioxide. A complete structural characterization was made by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The remarkable photocatalytic performance together with the stability of the nano-system was demonstrated by degradation of the methylene blue dye in water. The non-toxicity of the nano-system was established by testing the effect of the material on the reproductive cycle of Mytilus galloprovincialis in an aquatic environment. The originally synthesized material was also compared to conventional TiO2 with Au nanoparticles on top. The latter system showed a dispersion of Au nanoparticles in the liquid environment, due to their instability in the aqueous solution that clearly represents an environmental contamination issue. Thus, the results show that nanometric TiO2 wrapping of Au nanoparticles has great potential in eco-friendly water/wastewater purification.

  14. DNA-templated synthesis of PtAu bimetallic nanoparticle/graphene nanocomposites and their application in glucose biosensor

    PubMed Central

    2014-01-01

    In this paper, single-stranded DNA (ss-DNA) is demonstrated to functionalize graphene (GR) and to further guide the growth of PtAu bimetallic nanoparticles (PtAuNPs) on GR with high densities and dispersion. The obtained nanocomposites (PtAuNPs/ss-DNA/GR) were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS), and electrochemical techniques. Then, an enzyme nanoassembly was prepared by self-assembling glucose oxidase (GOD) on PtAuNP/ss-DNA/GR nanocomposites (GOD/PtAuNPs/ss-DNA/GR). The nanocomposites provided a suitable microenvironment for GOD to retain its biological activity. The direct and reversible electron transfer process between the active site of GOD and the modified electrode was realized without any extra electron mediator. Thus, the prepared GOD/PtAuNP/ss-DNA/GR electrode was proposed as a biosensor for the quantification of glucose. The effects of pH, applied potential, and temperature on the performance of the biosensor were discussed in detail and were optimized. Under optimal conditions, the biosensor showed a linearity with glucose concentration in the range of 1.0 to 1,800 μM with a detection limit of 0.3 μM (S/N = 3). The results demonstrate that the developed approach provides a promising strategy to improve the sensitivity and enzyme activity of electrochemical biosensors. PMID:24572068

  15. Non-centrosymmetric Au-SnO2 hybrid nanostructures with strong localization of plasmonic for enhanced photocatalysis application.

    PubMed

    Wu, Wei; Liao, Lei; Zhang, Shaofeng; Zhou, Juan; Xiao, Xiangheng; Ren, Feng; Sun, Lingling; Dai, Zhigao; Jiang, Changzhong

    2013-06-21

    We present an innovative approach to the production of sub-100 nm hollow Au-SnO2 hybrid nanospheres, employing a low-cost, surfactant-free and environmentally friendly solution-based route. The hollow hybrid nanostructures were synthesized using a seed-mediated hydrothermal method, which can be divided into two stages: (1) formation of multicore-shell Au@SnO2 nanoparticles (NPs) and (2) thermal diffusion and ripening to form hollow Au-SnO2 hybrid NPs. The morphology, optical properties and formation mechanism were determined by a collection of joint techniques. Photocatalytic degradation of Rhodamine B (RhB) in the liquid phase served as a probe reaction to evaluate the activity of the as-prepared hollow hybrid Au-SnO2 NPs under the irradiation of both visible light and ultraviolet light. Significantly, the as-obtained Au-SnO2 hybrid nanostructures exhibited enhanced visible light or UV photocatalytic abilities, remarkably superior to commercial pure SnO2 products and P25 TiO2, mainly owing to the effective electron hole separation at the SnO2-Au interfaces and strong localization of plasmonic near-fields effects. PMID:23685533

  16. Development and application of a two-tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis

    NASA Astrophysics Data System (ADS)

    Tan, Kim Chwee Daniel; Khang Goh, Ngoh; Sai Chia, Lian; Treagust, David F.

    2002-04-01

    This article describes the development and application of a two-tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis. The development of the diagnostic instrument was guided by the framework outlined by Treagust. The instrument was administered to 915 Grade 10 students (15 to 17 years old) from 11 schools after they had learned the theory involved in qualitative analysis and after a series of qualitative analysis practical sessions. The Cronbach alpha reliability of the instrument was .68, the facility indices ranged from .17 to .48, and the discrimination indices ranged from .20 to .53. The study showed that the Grade 10 students had difficulty understanding the reactions involved in the identification of cations and anions, for example, double decomposition reactions, the formation and reaction of complex salts, and thermal decomposition. The findings of the study and literature on practical work were used to develop a qualitative analysis teaching package.

  17. Application de la methode des sous-groupes au calcul Monte-Carlo multigroupe

    NASA Astrophysics Data System (ADS)

    Martin, Nicolas

    This thesis is dedicated to the development of a Monte Carlo neutron transport solver based on the subgroup (or multiband) method. In this formalism, cross sections for resonant isotopes are represented in the form of probability tables on the whole energy spectrum. This study is intended in order to test and validate this approach in lattice physics and criticality-safety applications. The probability table method seems promising since it introduces an alternative computational way between the legacy continuous-energy representation and the multigroup method. In the first case, the amount of data invoked in continuous-energy Monte Carlo calculations can be very important and tend to slow down the overall computational time. In addition, this model preserves the quality of the physical laws present in the ENDF format. Due to its cheap computational cost, the multigroup Monte Carlo way is usually at the basis of production codes in criticality-safety studies. However, the use of a multigroup representation of the cross sections implies a preliminary calculation to take into account self-shielding effects for resonant isotopes. This is generally performed by deterministic lattice codes relying on the collision probability method. Using cross-section probability tables on the whole energy range permits to directly take into account self-shielding effects and can be employed in both lattice physics and criticality-safety calculations. Several aspects have been thoroughly studied: (1) The consistent computation of probability tables with a energy grid comprising only 295 or 361 groups. The CALENDF moment approach conducted to probability tables suitable for a Monte Carlo code. (2) The combination of the probability table sampling for the energy variable with the delta-tracking rejection technique for the space variable, and its impact on the overall efficiency of the proposed Monte Carlo algorithm. (3) The derivation of a model for taking into account anisotropic

  18. Photoinduced ultrafast charge separation in colloidal 2-dimensional CdSe/CdS-Au hybrid nanoplatelets and corresponding application in photocatalysis.

    PubMed

    Chauhan, Himani; Kumar, Yogesh; Dana, Jayanta; Satpati, Biswarup; Ghosh, Hirendra N; Deka, Sasanka

    2016-08-25

    Multicomponent hybrid nanocrystals (HNC) consisting of a semiconductor and metallic domains are an important class of nanostructured materials demonstrating useful applications and interesting basic knowledge. In this scenario, Au nanoparticle (NP) islands of ∼2 nm have been grown on unique two dimensional (2D) CdSe/CdS core@shell hexagonal nanoheteroplatelets of 20 nm diameter to form unprecedented 2D CdSe/CdS-Au HNCs and detailed optical characterization has been carried out to determine the dimensionality based electron transfer dynamics on the ultrafast scale. Steady state optical absorption studies show that upon growing Au NPs onto the 2D nanoplates, a new band appears in the red region of the spectra (500-800 nm), which suggests a strong interaction between the exciton of the core-shell and the plasmon of the metal NPs. Fluorescence studies showed the quenching of emission of the semiconductor domains upon the growth of the metallic domains. Detailed optical and TRPL studies suggested efficient charge transfer from the 2D CdSe/CdS to the Au domains, irrespective of excitation wavelength. Femtosecond transient absorption studies suggest that the electron transfer from the 2D hybrid nanocrystals to the metal domain is on an ultrafast time scale (∼800 fs). No evidence is observed for charge transfer from the 2 nm Au domains to the semiconductor seeds. The broad absorption in the visible region of the hybrid nanocrystals and the ultrafast charge transfer facilitates very efficient photo-catalytic reactions under direct sun light, as a case study. PMID:27533050

  19. Qualitative analysis and applications of a kind of state-dependent impulsive differential equations

    NASA Astrophysics Data System (ADS)

    Wang, Fengyan; Pang, Guoping; Chen, Lansun

    2008-06-01

    This paper analyzes a certain type of impulsive differential equations (IDEs). Several useful theorems for its periodic solutions and their stabilities are given. The key idea is that a periodically time-dependent IDE can be transformed into the state-dependent IDE. As applications of our theory, the optimization problems in population dynamics are studied. That is, the maximum sustainable yields of single population models with periodically impulsive constant harvesting are discussed. Furthermore, we apply these results to the studies of the order-1 periodic solutions and their stability of a single population model with stage structure in which the mature is impulsively proportionally harvested while the immature is impulsively added with the constant.

  20. Low temperature synthesis of RGO-Au nanocomposite with apparently reduced time and its application as a chemical sensor

    NASA Astrophysics Data System (ADS)

    Tuz Johra, Fatima; Jung, Woo-Gwang

    2016-01-01

    For the first time, a reduced graphene oxide (RGO)-Au nanocomposites (NC) is synthesized at a low temperature by refluxing without a surfactant. Transmission electron microscopy suggests that Au nanoparticles (NPs) 10-20 nm in size are dispersed on the RGO thin film. X-ray diffraction study, UV-vis spectrometry, and Raman spectroscopy confirmed the reduction of graphene oxide (GO). This RGO-Au NC shows an excellent ability to detect Cr(VI) by electrochemical sensing, with good responses to both current and voltage. A glassy carbon electrode modified with the NC shows a significant voltammetric reduction peak. The voltammetric detection ability is highly dependent on the pH of the electrolyte. The large surface area of RGO's porous structure and the electroactive Au NPs both allow free exchange of reaction intermediates, resulting in significantly enhanced Cr(VI) reduction activity. The RGO-Au electrode shows a good linear response in a range of Cr(VI) concentrations from 10 to 800 μM and a high sensitivity of 0.0146 μA μM-1 with a 2.10 μM detection limit.

  1. A novel glucose biosensor platform based on Ag@AuNPs modified graphene oxide nanocomposite and SERS application.

    PubMed

    Gupta, Vinod Kumar; Atar, Necip; Yola, Mehmet Lütfi; Eryılmaz, Merve; Torul, Hilal; Tamer, Uğur; Boyacı, Ismail Hakkı; Ustündağ, Zafer

    2013-09-15

    This study represents a novel template demonstration of a glucose biosensor based on mercaptophenyl boronic acid (MBA) terminated Ag@AuNPs/graphene oxide (Ag@AuNPs-GO) nanomaterials. The nanocomposites were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) method. The TEM image shows that Ag@AuNPs in the nanocomposite is in the range of diameters of 10-20 nm. The nanocomposite was used for the determination of glucose through the complexation between boronic acid and diol groups of glucose. Thus, a novel glucose biosensor was further fabricated by immobilizing glucose oxidase (GOD) into MBA terminated Ag@AuNPs-GO nanocomposite film (MBA-Ag@AuNPs-GO). The linearity range of glucose was obtained as 2-6mM with detection limit of 0.33 mM. The developed biosensor was also applied successfully for the determination of glucose in blood samples. The concentration value of glucose in blood samples was calculated to be 1.97±0.002 mM from measurements repeated for six times. PMID:23816220

  2. Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

    NASA Astrophysics Data System (ADS)

    Gopinath, K.; Kumaraguru, S.; Bhakyaraj, K.; Thirumal, S.; Arumugam, A.

    2016-04-01

    Driven by the demand of pure TiO2, Au and Pt doped TiO2 NPs were successfully synthesized using Terminalia arjuna bark extract. The eco-friendly synthesized NPs were characterized by UV-Vis-DRS, ATR-FT-IR, PL, XRD, Raman, SEM with EDX and TEM analysis. The synthesized NPs were investigation for dye sensitized solar cell applications. UV-Vis-Diffused Reflectance Spectra clearly showed that the expected TiO2 inter band absorption below 306 nm, incorporation of gold shows surface plasma resonant (SPR) near 555 nm and platinum incorporated TiO2 NPs shows absorbance at 460 nm. The energy conversion efficiency for Au doped TiO2 NPs when compared to pure and Pt doped TiO2 NPs. In addition to that, Au noble metal present TiO2 matrix and an improve open-circuit voltage (Voc) of DSSC. Synthesized NPs was evaluated into antibacterial and antifungal activities by disk diffusion method. It is observed that NPs have not shown any activities in all tested bacterial and fungal strains. In this eco-friendly synthesis method to provide non toxic and environmental friendly nanomaterials can be used for solar energy device application.

  3. Using Qualitative Methods to Create a Home Health Web Application User Interface for Patients with Low Computer Proficiency

    PubMed Central

    Baier, Rosa R.; Cooper, Emily; Wysocki, Andrea; Gravenstein, Stefan; Clark, Melissa

    2015-01-01

    Introduction: Despite the investment in public reporting for a number of healthcare settings, evidence indicates that consumers do not routinely use available data to select providers. This suggests that existing reports do not adequately incorporate recommendations for consumer-facing reports or web applications. Methods: Healthcentric Advisors and Brown University undertook a multi-phased approach to create a consumer-facing home health web application in Rhode Island. This included reviewing the evidence base review to identify design recommendations and then creating a paper prototype and wireframe. We performed qualitative research to iteratively test our proposed user interface with two user groups, home health consumers and hospital case managers, refining our design to create the final web application. Results: To test our prototype, we conducted two focus groups, with a total of 13 consumers, and 28 case manager interviews. Both user groups responded favorably to the prototype, with the majority commenting that they felt this type of tool would be useful. Case managers suggested revisions to ensure the application conformed to laws requiring Medicare patients to have the freedom to choose among providers and could be incorporated into hospital workflow. After incorporating changes and creating the wireframe, we conducted usability testing interviews with 14 home health consumers and six hospital case managers. We found that consumers needed prompting to navigate through the wireframe; they demonstrated confusion through both their words and body language. As a result, we modified the web application’s sequence, navigation, and function to provide additional instructions and prompts. Discussion: Although we designed our web application for low literacy and low health literacy, using recommendations from the evidence base, we overestimated the extent to which older adults were familiar with using computers. Some of our key learnings and recommendations run

  4. Application of cladistics to terrane history—parsimony analysis of qualitative geological data

    NASA Astrophysics Data System (ADS)

    Young, Gavin C.

    Hypotheses of terrane dispersal or accretion can be represented graphically as branching diagrams (cladograms), but an assessment of competing hypotheses of terrane history requires a method of analysis of supporting evidence which resolves the most parsimonious explanation of all available data. Cladistics is a rigorous analytical method first developed for phylogeny reconstruction (i.e. biological history), but applicable to any hierarchical data set. Given appropriate definitions, the various types of geological, geophysical and biological data used to support hypotheses of fragmentation or fusion history for geological regions (terranes) assumed to have had independent geological histories can be organized hierarchically. Terrane fragmentation is equivalent to phylogenetic splitting of biological taxa, and standard algorithms for parsimony analysis may be directly applied. Terrane accretion may be represented as a coalescing area cladogram, and the supporting evidence also forms a hierarchical data set, but with two main differences. The less general attributes historically precede the more general (the reverse applies in phylogeny reconstruction), and the branching points (nodes on the cladogram), unlike hypothetical common ancestors in phylogeny reconstruction, represent defined geographic areas, with a geological structure which can be investigated. In cladistic reconstruction of evolutionary history the common ancestors are hypothetical, and their attributes can only be inferred from the distribution of attributes amongst the terminals (known biological taxa); in contrast, the end product of terrane accretion is a composite structure (geological province) within which juxtaposition of terranes may eliminate some of the possible historical sequences which led to its formation.

  5. Low temperature activation of Au/Ti getter film for application to wafer-level vacuum packaging

    NASA Astrophysics Data System (ADS)

    Wu, Ming; Moulin, Johan; Lani, Sébastien; Hallais, Géraldine; Renard, Charles; Bosseboeuf, Alain

    2015-03-01

    Non-evaporable getter (NEG) thin films based on alloys of transition metals have been studied by various authors for vacuum control in wafer-level packages of micro electro mechanical systems (MEMS). These materials have typically a relatively high activation temperature (300-450 °C) which is incompatible with some temperature sensitive MEMS devices. In this work we investigate the potential of Au/Ti system with a thin or ultrathin non oxidizable Au layer as a low activation temperature getter material. In this bilayer system, gettering activation is produced by thermal outdiffusion of titanium atoms through the gold film. The outdiffusion kinetics of titanium was modelled and characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS) at various temperatures. Results confirm that Au/Ti bilayer is a promising getter material for wafer-level packaging with an activation temperature below 300 °C for 1 h annealing time.

  6. The Application of Vibrational Spectroscopy Techniques in the Qualitative Assessment of Material Traded as Ginseng.

    PubMed

    Sandasi, Maxleene; Vermaak, Ilze; Chen, Weiyang; Viljoen, Alvaro

    2016-01-01

    The name "ginseng" is collectively used to describe several plant species, including Panax ginseng (Asian/Oriental ginseng), P. quinquefolius (American ginseng), P. pseudoginseng (Pseudoginseng) and Eleutherococcus senticosus (Siberian ginseng), each with different applications in traditional medicine practices. The use of a generic name may lead to the interchangeable use or substitution of raw materials which poses quality control challenges. Quality control methods such as vibrational spectroscopy-based techniques are here proposed as fast, non-destructive methods for the distinction of four ginseng species and the identification of raw materials in commercial ginseng products. Certified ginseng reference material and commercial products were analysed using hyperspectral imaging (HSI), mid-infrared (MIR) and near-infrared (NIR) spectroscopy. Principal component analysis (PCA) and (orthogonal) partial least squares discriminant analysis models (OPLS-DA) were developed using multivariate analysis software. UHPLC-MS was used to analyse methanol extracts of the reference raw materials and commercial products. The holistic analysis of ginseng raw materials revealed distinct chemical differences using HSI, MIR and NIR. For all methods, Eleutherococcus senticosus displayed the greatest variation from the three Panax species that displayed closer chemical similarity. Good discrimination models with high R²X and Q² cum vales were developed. These models predicted that the majority of products contained either /P. ginseng or P. quinquefolius. Vibrational spectroscopy and HSI techniques in tandem with multivariate data analysis tools provide useful alternative methods in the authentication of ginseng raw materials and commercial products in a fast, easy, cost-effective and non-destructive manner. PMID:27077839

  7. Development and Application of a Two-Tier Multiple Choice Diagnostic Instrument To Assess High School Students' Understanding of Inorganic Chemistry Qualitative Analysis.

    ERIC Educational Resources Information Center

    Tan, Kim Chwee Daniel; Goh, Ngoh Khang; Chia, Lian Sai; Treagust, David F.

    2002-01-01

    Describes the development and application of a two-tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis. Shows that the Grade 10 students had difficulty understanding the reactions involved in the identification of cations and anions, for example, double decomposition…

  8. Comparison of some morphological and absorption properties of the nanoparticles Au/TiO2 embedded films prepared by different technologies on the substrates for application in the plasmonic solar cell

    NASA Astrophysics Data System (ADS)

    Dao, Khac An; Thuy Nguyen, Thi; Huong Nguyen, Thi Mai; Nguyen, Duy Thien

    2015-03-01

    The nanoparticle Au/TiO2 embedded system plays a very important role in the plasmonic solar cell. The features of the nanoparticle embedded system will determine light enhancement, light absorption, scattering and localized surface plasmon resonance (LSPR), aiming to enhance the efficiency of the plasmatic solar cell. The characterizations of nanoparticles Au/TiO2 embedded system consist of many parameters: the sizes of nanoparticles (Au, TiO2), the weight ratio of Au to TiO2, the thickness of the single layer or multilayer of Au/TiO2, the arrangements of Au and TiO2 nanoparticles in integrated-matrix system, the light absorption, scattering and LSPR capacities of the Au/TiO2 system. These parameters, however, depend on the technological conditions, the structure of plasmonic solar cell as well as the used substrate materials. This paper presents some technological developments for nanoparticles Au/TiO2 embedded systems by different methods, including the preparation of the mixer Au/TiO2 solutions and fabrication of the nanoparticle Au/TiO2 systems with different Au percentages on several substrates (glass/ITO and AAO(Al)/Si…), and measured results of the morphological, structural and optical properties using FESEM, EDX, UV-vis spectroscopy. The comparisons of experiment results between different technology conditions and substrates (glass/ITO, AAO(Al)/Si…) are also shown and discussed with the aim of choosing the suitable technological process and technological conditions for application in the plasmonic solar cell.

  9. Observation of dynamic water microadsorption on Au surface

    SciTech Connect

    Huang, Xiaokang Gupta, Gaurav; Gao, Weixiang; Tran, Van; Nguyen, Bang; McCormick, Eric; Cui, Yongjie; Yang, Yinbao; Hall, Craig; Isom, Harold

    2014-05-15

    Experimental and theoretical research on water wettability, adsorption, and condensation on solid surfaces has been ongoing for many decades because of the availability of new materials, new detection and measurement techniques, novel applications, and different scales of dimensions. Au is a metal of special interest because it is chemically inert, has a high surface energy, is highly conductive, and has a relatively high melting point. It has wide applications in semiconductor integrated circuitry, microelectromechanical systems, microfluidics, biochips, jewelry, coinage, and even dental restoration. Therefore, its surface condition, wettability, wear resistance, lubrication, and friction attract a lot of attention from both scientists and engineers. In this paper, the authors experimentally investigated Au{sub 2}O{sub 3} growth, wettability, roughness, and adsorption utilizing atomic force microscopy, scanning electron microscopy, reflectance spectrometry, and contact angle measurement. Samples were made using a GaAs substrate. Utilizing a super-hydrophilic Au surface and the proper surface conditions of the surrounding GaAs, dynamic microadsorption of water on the Au surface was observed in a clean room environment. The Au surface area can be as small as 12 μm{sup 2}. The adsorbed water was collected by the GaAs groove structure and then redistributed around the structure. A model was developed to qualitatively describe the dynamic microadsorption process. The effective adsorption rate was estimated by modeling and experimental data. Devices for moisture collection and a liquid channel can be made by properly arranging the wettabilities or contact angles of different materials. These novel devices will be very useful in microfluid applications or biochips.

  10. Magnetic gold nanocatalyst (nanocat-Fe–Au): catalytic applications for the oxidative esterification and hydrogen transfer reactions

    EPA Science Inventory

    An efficient and sustainable protocol is described for the oxidative esterification of aldehydes and the reduction of aromatic nitro compounds that uses magnetically separable and reusable maghemite-supported gold nanocatalyst (nanocat-Fe-Au) under mild conditions. The complex ch...

  11. Patients’ experiences of using a smartphone application to increase physical activity: the SMART MOVE qualitative study in primary care

    PubMed Central

    Casey, Monica; Hayes, Patrick S; Glynn, Fergus; ÓLaighin, Gearóid; Heaney, David; Murphy, Andrew W; Glynn, Liam G

    2014-01-01

    Background Regular physical activity is known to help prevent and treat numerous non-communicable diseases. Smartphone applications (apps) have been shown to increase physical activity in primary care but little is known regarding the views of patients using such technology or how such technology may change behaviour. Aim To explore patients’ views and experiences of using smartphones to promote physical activity in primary care. Design and setting This qualitative study was embedded within the SMART MOVE randomised controlled trial, which used an app (Accupedo-Pro Pedometer) to promote physical activity in three primary care centres in the west of Ireland. Method Taped and transcribed semi-structured interviews with a purposeful sample of 12 participants formed the basis of the investigation. Framework analysis was used to analyse the data. Results Four themes emerged from the analysis: transforming relationships with exercise; persuasive technology tools; usability; and the cascade effect. The app appeared to facilitate a sequential and synergistic process of positive change, which occurred in the relationship between the participants and their exercise behaviour; the study has termed this the ‘Know-Check-Move’ effect. Usability challenges included increased battery consumption and adjusting to carrying the smartphone on their person. There was also evidence of a cascade effect involving the families and communities of participants. Conclusion Notwithstanding technological challenges, an app has the potential to positively transform, in a unique way, participants’ relationships with exercise. Such interventions can also have an associated cascade effect within their wider families and communities. PMID:25071063

  12. Preparation of Au-polydopamine functionalized carbon encapsulated Fe3O4 magnetic nanocomposites and their application for ultrasensitive detection of carcino-embryonic antigen

    PubMed Central

    Ji, Lei; Yan, Tao; Li, Yan; Gao, Jian; Wang, Qi; Hu, Lihua; Wu, Dan; Wei, Qin; Du, Bin

    2016-01-01

    A novel carbon encapsulated Fe3O4 nanoparticles embedded in two-dimensional (2D) porous graphitic carbon nanocomposites (Fe3O4@C@PGC nanocomposites) were synthesized by situ synthesis strategy, which provided a sensor platform owing to a large aspect ratio and porous structure. Polydopamine (PDA) were modified on the surface of Fe3O4@C@PGC nanocomposites through self-polymerization of dopamine, acting as both the reductant and template for one-step synthesis of gold nanoparticles. The prepared Au/PDA/Fe3O4@C@PGC nanocomposites show ferromagnetic features, extremely excellent electron transfer, large specific surface area and excellent dispersing property. These are conducive to the electrochemical signal output and the immobilization of antibody. In this work, a highly label-free sensitive magnetic immunosensor was developed based on Au/PDA/Fe3O4@C@PGC nanocomposites for the detection of carcino-embryonic antigen (CEA). The magnetic glassy carbon electrode was used to fix the Au/PDA/Fe3O4@C@PGC nanocomposites with the help of magnetic force. Under the optimal conditions, the immunosensor exhibited a wide linear range (0.001 ng/mL–20.0 ng/mL), a low detection limit (0.33 pg/mL), good reproducibility, selectivity and acceptable stability. The proposed sensing strategy may provide a potential application in the detection of other cancer biomarkers. PMID:26868035

  13. Tailored synthesis of photoactive TiO ₂ nanofibers and Au/TiO ₂ nanofiber composites: structure and reactivity optimization for water treatment applications.

    PubMed

    Nalbandian, Michael J; Greenstein, Katherine E; Shuai, Danmeng; Zhang, Miluo; Choa, Yong-Ho; Parkin, Gene F; Myung, Nosang V; Cwiertny, David M

    2015-02-01

    Titanium dioxide (TiO2) nanofibers with tailored structure and composition were synthesized by electrospinning to optimize photocatalytic treatment efficiency. Nanofibers of controlled diameter (30-210 nm), crystal structure (anatase, rutile, mixed phases), and grain size (20-50 nm) were developed along with composite nanofibers with either surface-deposited or bulk-integrated Au nanoparticle cocatalysts. Their reactivity was then examined in batch suspensions toward model (phenol) and emerging (pharmaceuticals, personal care products) pollutants across various water qualities. Optimized TiO2 nanofibers meet or exceed the performance of traditional nanoparticulate photocatalysts (e.g., Aeroxide P25) with the greatest reactivity enhancements arising from (i) decreasing diameter (i.e., increasing surface area), (ii) mixed phase composition [74/26 (±0.5) % anatase/rutile], and (iii) small amounts (1.5 wt %) of surface-deposited, more so than bulk-integrated, Au nanoparticles. Surface Au deposition consistently enhanced photoactivity by 5- to 10-fold across our micropollutant suite independent of their solution concentration, behavior that we attribute to higher photocatalytic efficiency from improved charge separation. However, the practical value of Au/TiO2 nanofibers was limited by their greater degree of inhibition by solution-phase radical scavengers and higher rate of reactivity loss from surface fouling in nonidealized matrixes (e.g., partially treated surface water). Ultimately, unmodified TiO2 nanofibers appear most promising for use as reactive filtration materials because their performance was less influenced by water quality, although future efforts must increase the strength of TiO2 nanofiber mats to realize such applications. PMID:25582552

  14. A simple approach to the synthesis of eccentric Au@SiO2 Janus nanostructures and their catalytic applications

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Yang, Di; Hu, Huicheng; Chen, Lei; Xu, Yong; Qu, Lili; Yang, Peipei; Zhang, Qiao

    2016-06-01

    In this paper, we present a simple method to synthesize eccentric Au@SiO2 Janus nanoparticles. By simply tuning the concentration of poly(vinyl pyrrolidone) (PVP), the surface of gold nanoparticle can be partially or fully wrapped with the amphiphilic ligand. As a result, Janus nanoparticle or concentric core-shell nanostructures can be obtained, respectively. A systematic study has been carried out to confirm the function of PVP molecules. The as-prepared Janus nanoparticle can act as a catalyst to catalyze the reduction of 4-nitrophenol, while the core-shell nanostructure is not active due to the coverage of dense silica shell. This work provides a robust and scalable method to produce Au@SiO2 Janus nanoparticles.

  15. Adsorption between TC-stabilized AuNPs and the phosphate group: application of the PTP1B activity assay.

    PubMed

    Lv, Jun; Wang, Xiaonan; Zhang, Yuanyuan; Li, Defeng; Zhang, Juan; Sun, Lizhou

    2015-12-01

    Based on the adsorption between tetracycline (TC) and phosphate groups, a general colorimetric method is explored in this work by using TC-stabilized gold nanoparticles (TC/AuNPs) and 4-aminophenyl phosphate-functionalized Fe3O4 magnetic nanoparticles (APP/MNPs). Taking protein tyrosine phosphatase 1B (PTP1B) as an example, 4-aminophenyl phosphate (APP) can be hydrolyzed into 4-aminophenol (AP) by PTP1B, resulting in the disappearance of the phosphate group on the outer layer of MNPs and the loss of corresponding adsorptive ability. Upon addition of TC/AuNP solution, TC/AuNPs will remain in the supernatant solution after magnetic separation and a high absorbance value can be observed. So PTP1B activity is related to the concentrations of TC/AuNPs in the supernatant solution. In this work, the enzyme activity can be determined at levels as low as 0.0885 U mL(-1) and over a linear detection range as wide as 0.1 U mL(-1) to 0.9 U mL(-1). Moreover, using the proposed method, the inhibition effect of betulinic acid (BA) and sodium orthovanadate (Na3VO4) on PTP1B activity can be tested with IC50 values of 30 μM and 4 μM, respectively. Therefore, a universal platform for the accurate colorimetric analysis of kinase and phosphatase activities can be established through the adsorption between TC and phosphate groups. PMID:26523458

  16. Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor

    PubMed Central

    Al-Ta’ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2016-01-01

    Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current–voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung’s method and Norde’s technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I–V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor. PMID:26799703

  17. Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor.

    PubMed

    Al-Ta'ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2016-01-01

    Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current-voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung's method and Norde's technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I-V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor. PMID:26799703

  18. First results on d+Au collisions from PHOBOS

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Noell, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sawicki, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Teng, R.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.; Zhang, J.

    2004-02-01

    We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at √SNN = 200 GeV, in the range 0.25 < pT < 6.0 GeV/c. With increasing collision centrality, the yield at high transverse momenta increases more rapidly than the overall particle density, leading to a strong modification of the spectral shape. This change in spectral shape is qualitatively different from observations in Au+Au collisions at the same energy. The results provide important information for discriminating between different models for the suppression of high-pT hadrons observed in Au+Au collisions.

  19. Pt@AuNPs integrated quantitative capillary-based biosensors for point-of-care testing application.

    PubMed

    Wu, Ze; Fu, Qiangqiang; Yu, Shiting; Sheng, Liangrong; Xu, Meng; Yao, Cuize; Xiao, Wei; Li, Xiuqing; Tang, Yong

    2016-11-15

    Current diagnostic technologies primarily rely on bulky and costly analytical instruments. Therefore, cost-effective and portable diagnosis tools that can be used for point-of-care tests (POCT) are highly desirable. In this study, we report a cost-effective, portable capillary-based biosensor for quantitative detection of biomarkers by the naked eye. This capillary-based biosensor was tested by measuring the distance of blue ink movement, which was directly correlated with the oxygen (O2) produced by efficient core-shell Pt@Au nanoparticles (Pt@AuNPs) catalysts decomposed hydrogen peroxide (H2O2). By linking the Pt@AuNPs with antibodies, capillary-based biosensor sandwich immunoassays were constructed. The concentrations of the target proteins were positively correlated with the distances of ink movement. To demonstrate their performance, the biosensors were used to detect the cancer biomarker sprostate-specific antigen (PSA) and carcinoembryonic antigen (CEA). The linear detection range (LDR) of the capillary-based biosensor for detecting PSA was from 0.02 to 2.5ng/mL, and the limit of detection (LOD) was 0.017ng/mL. LDR of the biosensor for detecting CEA was from 0.063 to 16ng/mL, and the LOD was 0.044ng/mL. For detection of PSA and CEA in clinical serum samples, the detection results of the capillary-based biosensor were well correlate with the results from of chemiluminescence immunoassays (CLIAs). Thus, the capillary-based biosensor may potentially be a useful strategy for point-of-care testing, in addition to being portable and cost effective. PMID:27240013

  20. Qualitative Evaluation.

    ERIC Educational Resources Information Center

    Stone, James C., Ed.; James, Raymond A., Ed.

    1981-01-01

    "Qualitative evaluation" is the theme of this issue of the California Journal of Teacher Education. Ralph Tyler states that evaluation is essentially descriptive, and using numbers does not solve basic problems. Martha Elin Vernazza examines the issue of objectivity in history and its implications for evaluation. She posits that the decisive…

  1. Gold nanowired: a linear (Au25)(n) polymer from Au25 molecular clusters.

    PubMed

    De Nardi, Marco; Antonello, Sabrina; Jiang, De-en; Pan, Fangfang; Rissanen, Kari; Ruzzi, Marco; Venzo, Alfonso; Zoleo, Alfonso; Maran, Flavio

    2014-08-26

    Au25(SR)18 has provided fundamental insights into the properties of clusters protected by monolayers of thiolated ligands (SR). Because of its ultrasmall core, 1 nm, Au25(SR)18 displays molecular behavior. We prepared a Au25 cluster capped by n-butanethiolates (SBu), obtained its structure by single-crystal X-ray crystallography, and studied its properties both experimentally and theoretically. Whereas in solution Au25(SBu)18(0) is a paramagnetic molecule, in the crystal it becomes a linear polymer of Au25 clusters connected via single Au-Au bonds and stabilized by proper orientation of clusters and interdigitation of ligands. At low temperature, [Au25(SBu)18(0)]n has a nonmagnetic ground state and can be described as a one-dimensional antiferromagnetic system. These findings provide a breakthrough into the properties and possible solid-state applications of molecular gold nanowires. PMID:25088331

  2. Application of Au-Sn eutectic bonding in hermetic radio-frequency microelectromechanical system wafer level packaging

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Choa, Sung-Hoon; Kim, Woonbae; Hwang, Junsik; Ham, Sukjin; Moon, Changyoul

    2006-03-01

    Development of packaging is one of the critical issues toward realizing commercialization of radio-frequency-microelectromechanical system (RF-MEMS) devices. The RF-MEMS package should be designed to have small size, hermetic protection, good RF performance, and high reliability. In addition, packaging should be conducted at sufficiently low temperature. In this paper, a low-temperature hermetic wafer level packaging scheme for the RF-MEMS devices is presented. For hermetic sealing, Au-Sn eutectic bonding technology at temperatures below 300°C is used. Au-Sn multilayer metallization with a square loop of 70 µm in width is performed. The electrical feed-through is achieved by the vertical through-hole via filling with electroplated Cu. The size of the MEMS package is 1 mm × 1 mm × 700 µm. The shear strength and hermeticity of the package satisfies the requirements of MIL-STD-883F. Any organic gases or contamination are not observed inside the package. The total insertion loss for the packaging is 0.075 dB at 2 GHz. Furthermore, the robustness of the package is demonstrated by observing no performance degradation and physical damage of the package after several reliability tests.

  3. Fixed-frequency and Frequency-agile (au, HTS) Microstrip Bandstop Filters for L-band Applications

    NASA Technical Reports Server (NTRS)

    Saenz, Eileen M.; Subramanyam, Guru; VanKeuls, Fred W.; Chen, Chonglin; Miranda, Felix A.

    2001-01-01

    In this work, we report on the performance of a highly selective, compact 1.83 x 2.08 cm(exp 2) (approx. 0.72 x 0.82 in(exp 2) microstrip line bandstop filter of YBa2CU3O(7-delta) (YBCO) on LaAlO3 (LAO) substrate. The filter is designed for a center frequency of 1.623 GHz for a bandwidth at 3 dB from reference baseline of less than 5.15 MHz, and a bandstop rejection of 30 dB or better. The design and optimization of the filter was performed using Zeland's IE3D circuit simulator. The optimized design was used to fabricate gold (Au) and High-Temperature Superconductor (HTS) versions of the filter. We have also studied an electronically tunable version of the same filter. Tunability of the bandstop characteristics is achieved by the integration of a thin film conductor (Au or HTS) and the nonlinear dielectric ferroelectric SrTiO3 in a conductor/ferroelectric/dielectric modified microstrip configuration. The performance of these filters and comparison with the simulated data will be presented.

  4. Applicability of Standards for Evaluation of Educational Programs Projects and Materials in an International Setting: Qualitative Research.

    ERIC Educational Resources Information Center

    Dockrell, W. B.

    1984-01-01

    This article responds to the "Standards for Evaluation of Educational Programs, Projects and Materials" by addressing three issues in qualitative research: (1) data quality; (2) data verification; and (3) collusion between evaluators and their sponsors. To be of maximum international value, the standards report needs more emphasis on qualitative…

  5. A Review of Qualitative Data Gathering Methods and Their Applications To Support Organizational Strategic Planning Processes. Study Number Six.

    ERIC Educational Resources Information Center

    Wright, Phillip C.; Geroy, Gary D.

    Exploring existing methodologies to determine whether they can be adapted or adopted to support strategic goal setting, this paper focuses on information gathering techniques as they relate to the human resource development professional's input into strategic planning processes. The information gathering techniques are all qualitative methods and…

  6. Precursor polymers for the carbon coating of Au@ZnO multipods for application as active material in lithium-ion batteries.

    PubMed

    Oschmann, Bernd; Tahir, Muhammad Nawaz; Mueller, Franziska; Bresser, Dominic; Lieberwirth, Ingo; Tremel, Wolfgang; Passerini, Stefano; Zentel, Rudolf

    2015-06-01

    The synthesis of statistical and block copolymers based on polyacrylonitrile, as a source for carbonaceous materials, and thiol-containing repeating units as inorganic nanoparticle anchoring groups is reported. These polymers are used to coat Au@ZnO multipod heteroparticles with polymer brushes. IR spectroscopy and transmission electron microscopy prove the successful binding of the polymer onto the inorganic nanostructures. Thermogravimetric analysis is applied to compare the binding ability of the block and statistical copolymers. Subsequently, the polymer coating is transformed into a carbonaceous (partially graphitic) coating by pyrolysis. The obtained carbon coating is characterized by Raman spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The benefit of the conformal carbon coating of the Au@ZnO multipods regarding its application as lithium-ion anode material is revealed by performing galvanostatic cycling, showing a highly enhanced and stabilized electrochemical performance of the carbon-coated particles (still 831 mAh g(-1) after 150 cycles) with respect to the uncoated ones (only 353 mAh g(-1) after 10 cycles). PMID:25598387

  7. α-Amylase monitoring by a novel amperometric biosensor based on Au electrode: its optimization, characterization, and application.

    PubMed

    Mengulluoglu, Umut; Altug, Cagri; Ertugrul, H Deniz; Yildiz, Abdulkerim; Ekici, E Melis; Dinckaya, Erhan

    2012-02-01

    A low-cost and sensitive amperometric biosensor was developed for the determination of α-amylase activity. The biosensor was constructed by immobilizing glucose oxidase-gelatin via glutaraldehyde on the Au electrode surface. Measurements were carried out chronoamperometrically at -0.7 V. Several parameters such as glucose oxidase activity, gelatin amount, and glutaraldehyde percentage for cross-linking were optimized. Optimum pH, optimum temperature, repeatability, and storage stabilities of the biosensor were identified. Under the optimum experimental conditions, a linear calibration curve was obtained for α-amylase between 0.819 and 13.110 U/ml. Sample analyses were carried out by detecting α-amylase activities in baker's yeast samples. PMID:21838534

  8. [Application of qualitative interviews in inheritance research of famous old traditional Chinese medicine doctors: ideas and experience].

    PubMed

    Luo, Jing; Fu, Chang-geng; Xu, Hao

    2015-04-01

    The inheritance of famous old traditional Chinese medicine (TCM) doctors plays an essential role in the fields of TCM research. Qualitative interviews allow for subjectivity and individuality within clinical experience as well as academic ideas of doctors, making it a potential appropriate research method for inheritance of famous old TCM doctors. We summarized current situations of inheritance research on famous old TCM doctors, and then discussed the feasibility of applying qualitative interviews in inheritance of famous old TCM doctors. By combining our experience in research on inheritance of famous old TCM doctors, we gave some advice on study design, interview implementation, data transcription and analyses , and report writing, providing a reference for further relevant research. PMID:26043577

  9. Fabrication and spectroscopic studies of folic acid-conjugated Fe3O4@Au core-shell for targeted drug delivery application

    NASA Astrophysics Data System (ADS)

    Karamipour, Sh.; Sadjadi, M. S.; Farhadyar, N.

    2015-09-01

    Gold coated magnetite core shell is a kind of nanoparticle that include magnetic iron oxide core with a thin layer nanogold. Fe3O4-gold core-shell nanostructure can be used in biomedical applications such as magnetic bioseparation, bioimaging, targeting drug delivery and cancer treatment. In this study, the synthesis and characterization of gold coated magnetite nanoparticles were discussed. Magnetite nanoparticles with an average size of 6 nm in diameter were synthesized by the chemical co-precipitation method and gold-coated Fe3O4 core-shell nanostructures were produced with an average size of 11.5 nm in diameter by reduction of Au3+ with citrate ion in the presence of Fe3O4. Folate-conjugated gold coated magnetite nanoparticles were synthesized to targeting folate receptor that is overexpressed on the surface of cancerous cells. For this purpose, we used L-cysteine, as a bi-functional linker for attachment to gold surface and it was linked to the gold nanoparticles surface through its thiol group. Then, we conjugated amino-terminated nanoparticles to folic acid with an amide-linkage formation. These gold magnetic nanoparticles were characterized by various techniques such as X-ray powder diffraction (XRD) analysis, Fourier transform infrared spectrometer (FT-IR), UV-visible spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dispersive analysis of X-ray (EDAX) and vibrating sample magnetometer (VSM) analysis. The magnetic and optical properties of Fe3O4 nanostructure were changed by gold coating and attachment of L-cysteine and folic acid to Fe3O4@Au nanoparticles.

  10. Nano-scale Au supported on Fe3O4: characterization and application in the catalytic treatment of 2,4-dichlorophenol

    NASA Astrophysics Data System (ADS)

    Gómez-Quero, Santiago; Cárdenas-Lizana, Fernando; Keane, Mark A.

    2012-07-01

    Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Gold nanoparticles supported on Fe3O4 have been tested in the gas phase (1 atm, 423 K) HDC of 2,4-dichlorophenol. Two 1% w/w supported gold catalysts have been prepared by: (i) stepwise deposition of Au on α-Fe2O3 with subsequent temperature-programmed reduction at 673 K (Au/Fe3O4-step); (ii) direct deposition of Au on Fe3O4 (Au/Fe3O4-dir). TEM analysis has established the presence of Au at the nano-scale with a greater mean diameter (7.6 nm) on Au/Fe3O4-dir relative to Au/Fe3O4-step (4.5 nm). We account for this difference in terms of stronger (electrostatic) precursor/support interactions in the latter that can be associated with the lower pH point of zero charge (with respect to the final deposition pH) for Fe2O3. Both catalysts promoted the preferential removal of the ortho-Cl substituent in 2,4-dichlorophenol, generating 4-chlorophenol and phenol as products of partial and total HDC, respectively, where Au/Fe3O4-step delivered a two-fold higher rate (2 × 10-4 molCl h-1 mAu-2) when compared with Au/Fe3O4-dir. This unprecedented selectivity response is attributed to activation of the ortho-C-Cl bond via interaction with electron-deficient Au nanoparticles. The results demonstrate the feasibility of a controlled recovery/recycling of chlorophenol waste using nano-structured Au catalysts.

  11. Superparamagnetic Au-Fe3O4 nanoparticles: one-pot synthesis, biofunctionalization and toxicity evaluation

    NASA Astrophysics Data System (ADS)

    Pariti, A.; Desai, P.; Maddirala, S. K. Y.; Ercal, N.; Katti, K. V.; Liang, X.; Nath, M.

    2014-09-01

    Superparamagnetic Au-Fe3O4 bifunctional nanoparticles have been synthesized using a single step hot-injection precipitation method. The synthesis involved using Fe(CO)5 as iron precursor and HAuCl4 as gold precursor in the presence of oleylamine and oleic acid. Oleylamine helps in reducing Au3+ to Au0 seeds which simultaneously oxidizes Fe(0) to form Au-Fe3O4 bifunctional nanoparticles. Triton® X-100 was employed as a highly viscous solvent to prevent agglomeration of Fe3O4 nanoparticles. Detailed characterization of these nanoparticles was performed by using x-ray powder diffraction, transmission electron microscopy, scanning tunneling electron microscopy, UV-visible spectroscopy, Mössbauer and magnetometry studies. To evaluate these nanoparticles’ applicability in biomedical applications, L-cysteine was attached to the Au-Fe3O4 nanoparticles and cytotoxicity of Au-Fe3O4 nanoparticles was tested using CHO cells by employing MTS assay. L-cysteine modified Au-Fe3O4 nanoparticles were qualitatively characterized using Fourier transform infrared spectroscopy and Raman spectroscopy; and quantitatively using acid ninhydrin assay. Investigations reveal that that this approach yields Au-Fe3O4 bifunctional nanoparticles with an average particle size of 80 nm. Mössbauer studies indicated the presence of Fe in Fe3+ in A and B sites (tetrahedral and octahedral, respectively) and Fe2+ in B sites (octahedral). Magnetic measurements also indicated that these nanoparticles were superparamagnetic in nature due to Fe3O4 region. The saturation magnetization for the bifunctional nanoparticles was observed to be ˜74 emu g-1, which is significantly higher than the previously reported Fe3O4 nanoparticles. Mössbauer studies indicated that there was no significant Fe(0) impurity that could be responsible for the superparamagnetic nature of these nanoparticles. None of the investigations showed any presence of other impurities such as Fe2O3 and FeOOH. These Au-Fe3O4 bifunctional

  12. Relativity, gold, closed-shell interactions, and CsAu.NH3.

    PubMed

    Pyykkö, Pekka

    2002-10-01

    The chemical properties of gold are strongly influenced by relativistic effects. One example is the large electronegativity of Au, which qualitatively explains the stability of (solid or liquid) cesium auride, Cs(+)Au(-), and other systems with Au(-) ions. An especially impressive compound is CsAu.NH(3), the structure and bonding of which are discussed. Future possibilities for finding further aurides are outlined. PMID:12370896

  13. Fabrication of High Sensitive Immunochromato Kit Using Au Colloid

    NASA Astrophysics Data System (ADS)

    Okamoto, Koji

    Au colloid have characteristics of surface plasmon resonance with absorption at 500 nm~600 nm wavelength. Surface on the citric acid Au colloid can be conjugated with protein eg. antibody. Various particle size of Au colloid makes it high sensitive immunochromato as diagnostics. High sensitive immunochromato will be useful for application of cancer marker eg. prostate specific antigen and influenza early diagnosis.

  14. Self-assembly of thiolated cyanine aggregates on Au(111) and Au nanoparticle surfaces

    NASA Astrophysics Data System (ADS)

    Menéndez, Guillermo O.; Cortés, Emiliano; Grumelli, Doris; Méndez de Leo, Lucila P.; Williams, Federico J.; Tognalli, Nicolás G.; Fainstein, Alejandro; Vela, María Elena; Jares-Erijman, Elizabeth A.; Salvarezza, Roberto C.

    2012-01-01

    Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show that CNN species adsorb on the Au surfaces by forming thiolate-Au bonds. We found that the J-aggregates are preferentially adsorbed on the Au(111) surface directly from the solution while adsorbed CNN monomers cannot organize into aggregates on the substrate surface. These results indicate that the CNN-Au interaction is not able to disorganize the large J-aggregates stabilized by π-π stacking to optimize the S-Au binding site but it is strong enough to hinder the π-π stacking when CNNs are chemisorbed as monomers. The optical properties of the J-aggregates remain active after adsorption. The possibility of covalently bonding CNN J-aggregates to Au planar surfaces and Au nanoparticles controlling the J-aggregate/Au distance opens a new path regarding their improved stability and the wide range of biological applications of both CNN and AuNP biocompatible systems.Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show

  15. First principles calculations of the optical and plasmonic response of Au alloys and intermetallic compounds.

    PubMed

    Keast, V J; Barnett, R L; Cortie, M B

    2014-07-30

    Pure Au is widely used in plasmonic applications even though its use is compromised by significant losses due to damping. There are some elements that are less lossy than Au (e.g. Ag or Al) but they will normally oxidize or corrode under ambient conditions. Here we examine whether alloying Au with a second element would be beneficial for plasmonic applications. In order to evaluate potential alternatives to pure Au, the density of states (DOS), dielectric function and plasmon quality factor have been calculated for alloys and compounds of Au with Al, Cd, Mg, Pd, Pt, Sn, Ti, Zn and Zr. Substitutional alloying of Au with Al, Cd, Mg and Zn was found to slightly improve the plasmonic response. Of the large number of intermetallic compounds studied, only AuAl2, Au3Cd, AuMg, AuCd and AuZn were found to be suitable for plasmonic applications. PMID:25001413

  16. First principles calculations of the optical and plasmonic response of Au alloys and intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Keast, V. J.; Barnett, R. L.; Cortie, M. B.

    2014-07-01

    Pure Au is widely used in plasmonic applications even though its use is compromised by significant losses due to damping. There are some elements that are less lossy than Au (e.g. Ag or Al) but they will normally oxidize or corrode under ambient conditions. Here we examine whether alloying Au with a second element would be beneficial for plasmonic applications. In order to evaluate potential alternatives to pure Au, the density of states (DOS), dielectric function and plasmon quality factor have been calculated for alloys and compounds of Au with Al, Cd, Mg, Pd, Pt, Sn, Ti, Zn and Zr. Substitutional alloying of Au with Al, Cd, Mg and Zn was found to slightly improve the plasmonic response. Of the large number of intermetallic compounds studied, only AuAl2, Au3Cd, AuMg, AuCd and AuZn were found to be suitable for plasmonic applications.

  17. Transport de particules massives dans un fluide turbulent: Application a l'erosion due au sable sur les parois d'une turbine hydraulique

    NASA Astrophysics Data System (ADS)

    Bergeron, Stephen

    Le transport de particules massives par un champ turbulent est un vaste domaine de la mécanique des fluides. Il possède de nombreuses applications comme par exemple le transport de sable dans une turbine hydraulique. En raison de la dureté des grains de quartz et des grandes vitesses de collision avec les parois métalliques, un phénomène d'érosion intensif se produit. Les dommages résultants peuvent diminuer le rendement de la turbine au cours des quelques mois suivant la mise en opération. L'objectif de cette thèse est de mettre au point un outil permettant de prédire ces zones d'érosion. Ce projet de recherche en contexte industriel a été réalisé en collaboration avec la compagnie General Electric Hydro du Canada. Dans un régime hautement turbulent, il est possible d'obtenir une expression suffisamment générale en utilisant une formulation partiellement empirique: l'équation de Basset- Boussinesq-Oseen modifiée. Ce choix de modèle tient compte du niveau de précision recherché et de la méthode numérique employée afin de résoudre la phase fluide. Il permet aussi d'éliminer plusieurs ambiguïtés fréquemment rencontrées dans la littérature et implementées dans certains codes commerciaux courants. La formulation mathématique du problème est effectuée dans un espace mixte Euler-Lagrange. Les paramètres dynamiques sont relies au type de particules et à l'intensité de la turbulence. Le code numérique résultant est le plus performant développé à ce jour (août 1998). Les trajectoires de plusieurs centaines de milliers de particules peuvent être simulées et visualisées de manière interactive sur une station de travail (SGI R4K, R8K et R10K). L'utilisateur du logiciel est libre de se déplacer dans l'espace à l'aide d'un environnement similaire a un ``simulateur de vol''. Il peut ainsi analyser les détails du processus d'érosion de même que l'écoulement du fluide dans la turbine. Les zones d'érosion obtenues à l

  18. A General Survey of Qualitative Research Methodology.

    ERIC Educational Resources Information Center

    Cary, Rick

    Current definitions and philosophical foundations of qualitative research are presented; and designs, evaluation methods, and issues in application of qualitative research to education are discussed. The effects of positivism and the post-positivist era on qualitative research are outlined, and naturalist and positivist approaches are contrasted.…

  19. Au-Ag@Au Hollow Nanostructure with Enhanced Chemical Stability and Improved Photothermal Transduction Efficiency for Cancer Treatment.

    PubMed

    Jiang, Tongtong; Song, Jiangluqi; Zhang, Wenting; Wang, Hao; Li, Xiaodong; Xia, Ruixiang; Zhu, Lixin; Xu, Xiaoliang

    2015-10-01

    Despite the fact that Au-Ag hollow nanoparticles (HNPs) have gained much attention as ablation agents for photothermal therapy, the instability of the Ag element limits their applications. Herein, excess Au atoms were deposited on the surface of a Au-Ag HNP by improving the reduction power of l-ascorbic acid (AA) and thereby preventing the reaction between HAuCl4 and the Ag element in the Au-Ag alloy nanostructure. Significantly, the obtained Au-Ag@Au HNPs show excellent chemical stability in an oxidative environment, together with remarkable increase in extinction peak intensity and obvious narrowing in peak width. Moreover, finite-difference time-domain (FDTD) was used to simulate the optical properties and electric field distribution of HNPs. The calculated results show that the proportion of absorption cross section in total extinction cross section increases with the improvement of Au content in HNP. As predicted by the theoretical calculation results, Au-Ag@Au nanocages (NCs) exhibit a photothermal transduction efficiency (η) as high as 36.5% at 808 nm, which is higher than that of Au-Ag NCs (31.2%). Irradiated by 808 nm laser at power densities of 1 W/cm(2), MCF-7 breast cancer cells incubated with PEGylated Au-Ag@Au NCs were seriously destroyed. Combined together, Au-Ag@Au HNPs with enhanced chemical stability and improved photothermal transduction efficiency show superior competitiveness as photothermal agents. PMID:26371629

  20. Designing a web-application to support home-based care of childhood CKD stages 3-5: Qualitative study of family and professional preferences

    PubMed Central

    2014-01-01

    Background There is a lack of online, evidence-based information and resources to support home-based care of childhood CKD stages 3-5. Methods Qualitative interviews were undertaken with parents, patients and professionals to explore their views on content of the proposed online parent information and support (OPIS) web-application. Data were analysed using Framework Analysis, guided by the concept of Self-efficacy. Results 32 parents, 26 patients and 12 professionals were interviewed. All groups wanted an application that explains, demonstrates, and enables parental clinical care-giving, with condition-specific, continously available, reliable, accessible material and a closed communication system to enable contact between families living with CKD. Professionals advocated a regularly updated application to empower parents to make informed health-care decisions. To address these requirements, key web-application components were defined as: (i) Clinical care-giving support (information on treatment regimens, video-learning tools, condition-specific cartoons/puzzles, and a question and answer area) and (ii) Psychosocial support for care-giving (social-networking, case studies, managing stress, and enhancing families’ health-care experiences). Conclusions Developing a web-application that meets parents’ information and support needs will maximise its utility, thereby augmenting parents’ self-efficacy for CKD caregiving, and optimising outcomes. Self-efficacy theory provides a schema for how parents’ self-efficacy beliefs about management of their child’s CKD could potentially be promoted by OPIS. PMID:24548640

  1. Application of fuzzy logic techniques for the qualitative interpretation of preferences in a collective questionnaire for users of wheelchairs.

    PubMed

    Lafuente, R; Page, A; Sánchez-Lacuesta, J; Tortosa, L

    1998-01-01

    Active participation of users in the evaluation of technical aids is essential, since they are part of the interface with the system and constitute a fundamental source of design criteria. In this study, 88 active users of wheelchairs were interviewed by means of a written questionnaire about their opinion concerning the adaptation of his/her wheelchair to the office workplace. A conceptual framework was introduced linking objective measurements of the user-wheelchair interface to the subjective preferences expressed by the user. Discriminant analysis was used in order to select and quantify the importance of the most significant factors influencing the user's opinions. Fuzzy logic was introduced for the qualitative interpretation of the relationship between those significant factors, based on an inductive algorithm for generating fuzzy rules. Fuzzy logic enables a person to model the uncertainty within the subjective formulation of knowledge or opinions. From the results, a mismatch between actual performance of conventional wheelchairs and requirements of office work became evident. The proposed methods make it possible to determine reliable rules explaining subjective preferences; thus, they provide a flexible means of interpreting user questionnaires and obtaining new design criteria. PMID:9505257

  2. Au nanorod helical superstructures with designed chirality.

    PubMed

    Lan, Xiang; Lu, Xuxing; Shen, Chenqi; Ke, Yonggang; Ni, Weihai; Wang, Qiangbin

    2015-01-14

    A great challenge for nanotechnology is to controllably organize anisotropic nanomaterials into well-defined three-dimensional superstructures with customized properties. Here we successfully constructed anisotropic Au nanorod (AuNR) helical superstructures (helices) with tailored chirality in a programmable manner. By designing the 'X' pattern of the arrangement of DNA capturing strands (15nt) on both sides of a two-dimensional DNA origami template, AuNRs functionalized with the complementary DNA sequences were positioned on the origami and were assembled into AuNR helices with the origami intercalated between neighboring AuNRs. Left-handed (LH) and right-handed (RH) AuNR helices were conveniently accomplished by solely tuning the mirrored-symmetric 'X' patterns of capturing strands on the origami. The inter-rod distance was precisely defined as 14 nm and inter-rod angle as 45°, thus a full helix contains 9 AuNRs with its length up to about 220 nm. By changing the AuNR/origami molar ratio in the assembly system, the average number of AuNR in the helices was tuned from 2 to 4 and 9. Intense chiroptical activities arose from the longest AuNR helices with a maximum anisotropy factor of ∼0.02, which is highly comparable to the reported macroscopic AuNR assemblies. We expect that our strategy of origami templated assembly of anisotropic chiral superstructures would inspire the bottom-up fabrication of optically active nanostructures and shed light on a variety of applications, such as chiral fluids, chiral signal amplification, and fluorescence combined chiral spectroscopy. PMID:25516475

  3. Conceptual design study of concentrator enhanced solar arrays for space applications. 2kW Si and GaAs systems at 1 AU

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The effect of concentration level on the specific power for a deployable, thin, gallium arsenide cell array in geosynchronous orbit for 10 years in conjunction with a two dimensional flat plate trough concentrator (V trough) and also with a multiple flat plate concentrator was investigated as well as the effects for a conventional silicon cell array on a rigid substrate. For application to a thin GaAs array at 1 AU for 10 years, the V trough produces a 19% benefit in specific power and a dramatic reduction in array area, while the multiple flat plate collector design is not only of no benefit, but is a considerable detriment. The benefit it achieves by reducing array area is duplicated by the 2D design. For the silicon array on a rigid substrate, improvement in performance due to a concentrator with ordinary mirror coating is quite small: 9% increase in specific power, and 13% reduction in array area. When the concentrator mirrors are coated with an improved cold mirror coating, somewhat more significant results are obtained: 31% specific power improvement; and 27% area reduction. In both cases, a 10 year exposure reduces BOL output by 23%.

  4. High performance Au/PZT/TiOxNy/Si MFIS structure for next generation ferroelectric memory applications

    NASA Astrophysics Data System (ADS)

    Sharma, Deepak K.; Khosla, Robin; Sharma, Satinder K.

    2015-05-01

    The Metal-Ferroelectric-Insulator-Semiconductor (MFIS) capacitors with thin 20 nm lead zirconate titanate (PZT) and titanium oxynitride (TiOxNy) buffer layer were fabricated by RF magnetron sputtering technique and characterized. TiOxNy as a buffer layer deposited for the first time for MFIS application at different thicknesses and fabricated structure was found to exhibit excellent electrical characteristics at 14 nm TiOxNy. Memory window of 0.4 V was found at low sweep voltage of ± 3 V which increases to 1.8 V at sweep voltage of ±14 V indicating multilevel data storage. Moreover the fabricated structure possesses low leakage current density of ˜4 µA/cm2 at 36 nm TiOxNy which increases to 12 µA/cm2 at 4 nm TiOxNy at 5 V, reasonable limit. Furthermore, the fabricated structure possesses outstanding data retention capability at 14 nm TiOxNy; the high and low capacitance becomes constant after few seconds and clearly distinguishable for 1h and 30 min. This shows that proposed MFIS structure is suitable for high performance ferroelectric memory applications.

  5. Preparation of Au Nanoparticles Immobilized Cross-Linked Poly(4-vinylpyridine) Nanofibers and Their Catalytic Application for the Reduction of 4-Nitrophenol.

    PubMed

    Qin, Qi-Hu; Na, Hui; Zhang, Chunyu; Yu, Qizhou; Zhang, Xue-Quan; Zhang, He-Xin

    2015-05-01

    Catalytic nanofibers are prepared by the immobilization of Au nanoparticles (AuNPs) onto the surface of cross-linked electrospun poly(4-vinylpyridine) (P4VP) nanofibers. The crosslinking of the P4VP nanofibers by 1,4-diiodobutane via quaternization reaction greatly enhances the stability of the nanofibers against the solvent dissolution, which can then be used as promising platform for the immobilization of catalytic metal nanoparticles. The AuNPs immobilized cross-linked P4VP nanofibers have shown a good catalytic activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). PMID:26505022

  6. Facile synthesis and intraparticle self-catalytic oxidation of dextran-coated hollow Au-Ag nanoshell and its application for chemo-thermotherapy.

    PubMed

    Jang, Hongje; Kim, Young-Kwan; Huh, Hyun; Min, Dal-Hee

    2014-01-28

    Galvanic replacement reaction is a useful method to prepare various hollow nanostructures. We developed fast and facile preparation of biocompatible and structurally robust hollow Au-Ag nanostructures by using dextran-coated Ag nanoparticles. Oxidation of the surface dextran alcohols was enabled by catalytic activity of the core Au-Ag nanostructure, introducing carbonyl groups that are useful for further bioconjugation. Subsequent doxorubicin (Dox) conjugation via Schiff base formation was achieved, giving high payload of approximately 35 000 Dox per particle. Near-infrared-mediated photothermal conversion showed high efficacy of the Dox-loaded Au-Ag nanoshell as a combinational chemo-thermotherapy to treat cancer cells. PMID:24383549

  7. A qualitative exploration of experiences of overweight young and older adults. An application of the integrated behaviour model.

    PubMed

    Robertson, Annaleise; Mullan, Barbara; Todd, Jemma

    2014-04-01

    While rates of obesity continue to increase, weight-loss interventions to date have not been hugely successful. The purpose of this study was to explore the specific factors that are relevant to weight control in overweight and obese young adults compared to older adults, within the context of the theory of planned behaviour (TPB). A qualitative methodology with purposive sampling was used. Semi-structured interviews were conducted with 23 young adults and older adults who were currently overweight or obese. The research was informed by thematic analysis. A mixed deductive-inductive approach that was structured around but not limited to TPB constructs was applied. Themes mapped onto the TPB behaviour well, with additional themes of motivation, and knowledge and experience emerging. Differences across groups included motivators to weight loss (e.g. appearance and confidence for young adults, health for older adults), importance of social influences, and perceptions of control (e.g. availability and cost for young adults, age and energy for older adults). Similarities across groups included attitudes towards being overweight and losing weight, and the value of preparation and establishment of a healthy routine. Finally, across both groups, knowledge and confidence in ability to lose weight appeared adequate, despite failed attempts to do so. The different experiences identified for younger and older adults can be used to inform future tailored weight-loss interventions that are relevant to these age groups, and the TPB could provide a useful framework. Additional intervention strategies, such as improving behavioural routine and improving self-regulation also warrant further investigation. PMID:24462493

  8. Publishing Qualitative Research.

    ERIC Educational Resources Information Center

    Smith, Mary Lee

    1987-01-01

    Article defines qualitative research and describes the form that an article based on qualitative research might take. Encourages readers to submit articles based on qualitative research to the American Educational Research Journal. (RB)

  9. Ultra-relativistic Au+Au and d+Au collisions:

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Hauer, M.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Seals, H.; Sedykh, I.; Skulski, W.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    In this talk I will review PHOBOS data on charged particle multiplicities, obtained in Au+Au and d+Au collisions at RHIC. The general features of the Au+Au pseudorapidity distributions results will be discussed and compared to those of /line{p}p collisions. The total charged particle multiplicity, scaled by the number of participant pairs, is observed to be about 40% higher in Au+Au collisions than in /line{p}p and d+Au systems, but, surprisingly at the same level of e+e- collisions. Limiting fragmentation scaling is seen to be obeyed in Au+Au collisions.

  10. A study on the effect of low energy ion beam irradiation on Au/TiO2 system for its application in photoelectrochemical splitting of water

    NASA Astrophysics Data System (ADS)

    Verma, Anuradha; Srivastav, Anupam; Sharma, Dipika; Banerjee, Anamika; Sharma, Shailja; Satsangi, Vibha Rani; Shrivastav, Rohit; Avasthi, Devesh Kumar; Dass, Sahab

    2016-07-01

    Nanostructured TiO2 thin films were deposited on indium tin oxide (ITO) substrate via sol-gel technique and were modified by plasmonic Au layer. The plasmonic Au modified TiO2 (Au/TiO2) thin films were then irradiated with 500 keV Ar2+ ion beam at different ion fluences viz. 1 × 1016, 3 × 1016 and 1 × 1017 to study the effect of nuclear energy deposition on the morphology, crystallinity, band gap, surface plasmon resonance (SPR) peak exhibited by Au particles and photoelectrochemical properties of the system. Prepared thin films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS) measurements and UV-visible spectroscopy. The photoelectrochemical measurements revealed that both Au/TiO2 and Au/TiO2 thin film irradiated at 1 × 1016 fluence exhibits enhanced photoelectrochemical response in comparison to pristine TiO2. The film irradiated at 1 × 1016 fluence offered maximum applied bias photon-to-current efficiency (ABPE) and shows 6 times increment in photocurrent density which was attributed to more negative flat band potential, maximum decrease in band gap, high open circuit voltage (Voc) and reduced charge transfer resistance.

  11. Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications

    NASA Astrophysics Data System (ADS)

    Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

    2015-03-01

    Double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe3O4/TiO2 support by a in situ reduction of HAuCl4 with NaBH4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe3O4/TiO2 microspheres. The sea urchin-like structure composed of TiO2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe3O4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe3O4/TiO2/Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min-1 and turnover frequency is 5457 h-1.

  12. Β-cyclodextrin polymer as a linker to fabricate ternary nanocomposites AuNPs/pATP-β-CDP/rGO and their electrochemical application.

    PubMed

    Chen, Ming; Shen, Xiao; Liu, Peipei; Wei, Ying; Meng, Yang; Zheng, Gang; Diao, Guowang

    2015-03-30

    Based on the self-assembly strategy, β-cyclodextrin polymer (β-CDP) was used as a linker to connect reduced graphene oxide (rGO) and p-aminothiophenol (pATP). Then, pre-prepared gold nanoparticles (AuNPs) can self-assemble onto the surface of pATP-β-CDP/rGO to obtain new ternary nanocomposites AuNPs/pATP-β-CDP/rGO. The amount or the density of AuNPs can be adjusted by changing the concentration of pATP. UV-vis and (1)H NMR spectra confirmed the formation of inclusion complex between pATP and β-CDP. β-CDP might improve the dispersity of rGO in aqueous and the surface property of rGO. AuNPs/pATP-β-CDP/rGO modified electrode displayed high electrochemical response toward a pesticide-imidacloprid (IDP). The enrichment capability and molecular recognition of β-CDP and the catalytic property of AuNPs for IDP molecules synergistically promoted the electrochemical response of rGO modified electrode. Additionally, ternary nanocomposites exhibited the good electrocatalytic performance for oxygen reduction in O2-saturated 0.1M H2SO4 solution. The proposed synthesis strategy provided a facile, feasible and effective method for development of electrochemical sensors and Au-based catalysts for fuel cells. PMID:25563941

  13. Qualitative methods for assessing risk

    SciTech Connect

    Mahn, J.A.; Hannaman, G.W.; Kryska, P.

    1995-04-01

    The Department of Energy`s (DOE) non-nuclear facilities generally require only a qualitative accident analysis to assess facility risks in accordance with DOE Order 5481.1B, Safety Analysis and Review System. Achieving a meaningful qualitative assessment of risk necessarily requires the use of suitable non-numerical assessment criteria. Typically, the methods and criteria for assigning facility-specific accident scenarios to the qualitative severity and likelihood classification system in the DOE order requires significant judgment in many applications. Systematic methods for more consistently assigning the total accident scenario frequency and associated consequences are required to substantiate and enhance future risk ranking between various activities at Sandia National Laboratories (SNL). SNL`s Risk Management and National Environmental Policy Act (NEPA) Department has developed an improved methodology for performing qualitative risk assessments in accordance wi the DOE order requirements. Products of this effort are an improved set of qualitative description that permit (1) definition of the severity for both technical and programmatic consequences that may result from a variety of accident scenarios, and (2) qualitative representation of the likelihood of occurrence. These sets of descriptions are intended to facilitate proper application of DOE criteria for assessing facility risks.

  14. Identification of Au–S complexes on Au(100)

    DOE PAGESBeta

    Walen, Holly; Liu, Da -Jiang; Oh, Junepyo; Yang, Hyun Jin; Kim, Yousoo; Thiel, P. A.

    2016-01-25

    In this study, using a combination of scanning tunneling microscopy and density functional theory (DFT) calculations, we have identified a set of related Au–S complexes that form on Au(100), when sulfur adsorbs and lifts the hexagonal surface reconstruction. The predominant complex is diamond-shaped with stoichiometry Au4S5. All of the complexes can be regarded as combinations of S–Au–S subunits. The complexes exist within, or at the edges of, p(2 × 2) sulfur islands that cover the unreconstructed Au regions, and are observed throughout the range of S coverage examined in this study, 0.009 to 0.12 monolayers. A qualitative model is developedmore » which incorporates competitive formation of complexes, Au rafts, and p(2 × 2) sulfur islands, as Au atoms are released by the surface structure transformation.« less

  15. Structural, electronic and magnetic properties of Au-based monolayer derivatives in honeycomb structure

    NASA Astrophysics Data System (ADS)

    Kapoor, Pooja; Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.

    2016-05-01

    We present electronic properties of atomic layer of Au, Au2-N, Au2-O and Au2-F in graphene-like structure within the framework of density functional theory (DFT). The lattice constant of derived monolayers are found to be higher than the pristine Au monolayer. Au monolayer is metallic in nature with quantum ballistic conductance calculated as 4G0. Similarly, Au2-N and Au2-F monolayers show 4G0 and 2G0 quantum conductance respectively while semiconducting nature with calculated band gap of 0.28 eV has been observed for Au2-O monolayer. Most interestingly, half metalicity has been predicted for Au2-N and Au2-F monolayers. Our findings may have importance for the application of these monolayers in nanoelectronic and spintronics.

  16. Initial-state geometry and fluctuations in Au + Au, Cu + Au, and U + U collisions at energies available at the BNL Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Schenke, Björn; Tribedy, Prithwish; Venugopalan, Raju

    2014-06-01

    We study within the IP-Glasma and two-component MC-Glauber models the effects of initial-state geometry and fluctuations on multiplicities and eccentricities for several collision species at the Relativistic Heavy Ion Collider (RHIC). These include copper-gold (Cu + Au), gold-gold (Au + Au), and uranium-uranium (U + U) collisions. The multiplicity densities per participant pair are very similar in all systems studied. Ellipticities vary strongly between collision systems, most significantly for central collisions, while fluctuation driven odd moments vary little between systems. Event-by-event distributions of eccentricities in mid-central collisions are wider in Cu + Au relative to Au + Au and U + U systems. An anticorrelation between multiplicity and eccentricity is observed in ultracentral U + U collisions which is weaker in the IP-Glasma model than the two-component MC-Glauber model. In ultracentral Au + Au collisions the two models predict opposite signs for the slope of this correlation. Measurements of elliptic flow as a function of multiplicity in such central events can therefore be used to discriminate between models with qualitatively different particle production mechanisms.

  17. Au@Ag Heterogeneous Nanorods as Nanozyme Interfaces with Peroxidase-Like Activity and Their Application for One-Pot Analysis of Glucose at Nearly Neutral pH.

    PubMed

    Han, Lei; Li, Cuncheng; Zhang, Tao; Lang, Qiaolin; Liu, Aihua

    2015-07-01

    As substitutes for natural peroxidases, most nanomaterial-based enzyme mimetics (nanozymes) have unique properties such as high stability, low-cost, large surface area, and high catalytic activity. However, they usually work in acidic conditions and thus impede their real applications. In this work, by modulating the nanostructure, composition, and surface property of the bimetallic materials, the positively charged poly(diallyldimethylammonium)-stabilized Au@Ag heterogeneous nanorods (NRs) were developed as synergistic peroxidase-like interfaces, which exhibited high activity over a wide pH range (pH 4.0-6.5) using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the chromogenic substrate. At pH 6.5, the peroxidase-like activity for the Au@Ag heterogeneous NRs was stable and optimal within 20-40 °C. Moreover, the Au@Ag heterogeneous NRs showed excellent temperature stability and long-term storage stability. Given these characters, the detection of H2O2 at pH 6.5 was proposed on the basis of the Au@Ag heterogeneous NRs catalyzing the colorimetric reaction of H2O2 and ABTS, where the oxidized ABTS showed a typical absorption peak at 414 nm. The absorbance at 414 nm was linear with H2O2 concentration from 0.01 to 10 mM. Further, considering that Au@Ag heterogeneous NRs and glucose oxidase (GOx) have similar optimal pH for catalytic activities, a novel one-pot method for the detection of glucose was developed by the coupled catalytic reaction using GOx, Au@Ag heterogeneous NRs, and ABTS at nearly neutral pH (pH 6.5) and 37 °C. This proposed method had simple and rapid processes, wide linear range (0.05-20 mM), and reliability for the successful analysis of real samples. On the basis of these attractive and unique characteristics, Au@Ag heterogeneous NRs can become promising substitutes for peroxidase in analytical chemistry and environmental science. PMID:26076372

  18. Qualitative research: comments and controversies.

    PubMed

    Schutz, R W

    1989-03-01

    Larry Locke's timely and well-written introduction to qualitative research procedures will undoubtedly serve its purpose. It makes us reassess our traditional beliefs and practices, educates us on the rudiments of qualitative methodology, and, hopefully, makes us more tolerant and appreciative of alternate ways of conducting research. Although Locke focuses his paper on pedagogical research issues, it is important to realize that many other sub-disciplines within the general field of physical education also utilize qualitative procedures. For example, 10 years ago Martens (1979) called for a paradigm shift in sport psychology by appealing to researchers to abandon their labs and to embark on naturalistic field studies. While North American sport psychologists, and psychologists in general, have been slow to formalize qualitative techniques, the European psychology community has been much more active (e.g., Ashworth, Giorgi, & de Koning, 1986). Perhaps Locke's article will encourage researchers in all our sub-disciplines to consider the utility of qualitative research. Hopefully, readers will treat Locke's article as an introduction to the broad area of qualitative research and not as a rigorous set of procedures for conducting participant observation research in school physical education studies. Additionally, it must be recognized that there are other approaches and other applications, that the area has its critics and its unresolved methodological problems, and that qualitative research does not necessarily exclude the application of formalized data analyses. Keeping these issues in mind, the addition of qualitative approaches to our repetoire of research methodologies can only enhance the quality of research in physical education and exercise and sport science. PMID:2489822

  19. The Gap between Individual Perception and Compliance: A Qualitative Follow-Up Study of the Surgical Safety Checklist Application

    PubMed Central

    Sendlhofer, Gerald; Lumenta, David Benjamin; Leitgeb, Karina; Kober, Brigitte; Jantscher, Lydia; Schanbacher, Monika; Berghold, Andrea; Pregartner, Gudrun; Brunner, Gernot; Tax, Christa; Kamolz, Lars Peter

    2016-01-01

    Background “The Surgical Safety Checklist (SSC) is important, but we don’t use it adequately” is a well-suited statement that reflects the SSC's application in hospitals. Our aim was to follow up on our initial study on compliance (2014) by analysing differences between individual perception and compliance with the SSC. Methods We conducted a follow-up online survey to assess healthcare professionals’ individual perception of, as well as satisfaction and compliance with the SSC three years following its thorough implementation. Results 171 (19.5%) of 875 operating team members completed the online survey. 99.4% confirmed using the SSC. Self-estimated subjective knowledge about the intention of the checklist was high, whereas objective knowledge was moderate, but improved as compared to 2014. According to an independent audit the SSC was used in 93.1% of all operations and among the SSCs used the completion rate was 57.2%. The use of the SSC was rated as rather easy [median (IQR): 7 (6–7)], familiar [7 (6–7)], generally important [7 (7–7)], and good for patients [7 (6–7)] as well as for employees [7 (7–7)]. Only comfort of use was rated lower [6 (5–7)]. Conclusion There is a gap between individual perception and actual application of the SSC. Despite healthcare professionals confirming the importance of the SSC, compliance was moderate. The introduction of SSCs in the health care sector remains a constant challenge and requires continuous re-evaluation as well as a sensible integration into existing workflows in hospitals. PMID:26925579

  20. Collective flow in Au + Au collisions

    SciTech Connect

    Ritter, H.G.; EOS Collaboration

    1994-05-01

    Based on a preliminary sample of Au + Au collisions in the EOS time projection chamber at the Bevalac, we study sideward flow as a function of bombarding energy between 0.25A GeV and 1.2A GeV. We focus on the increase in in-plane transverse momentum per nucleon with fragment mass. We also find event shapes to be close to spherical in the most central collisions, independent of bombarding energy and fragment mass up to {sup 4}He.

  1. Comparison of nine different real-time PCR chemistries for qualitative and quantitative applications in GMO detection.

    PubMed

    Buh Gasparic, Meti; Tengs, Torstein; La Paz, Jose Luis; Holst-Jensen, Arne; Pla, Maria; Esteve, Teresa; Zel, Jana; Gruden, Kristina

    2010-03-01

    Several techniques have been developed for detection and quantification of genetically modified organisms, but quantitative real-time PCR is by far the most popular approach. Among the most commonly used real-time PCR chemistries are TaqMan probes and SYBR green, but many other detection chemistries have also been developed. Because their performance has never been compared systematically, here we present an extensive evaluation of some promising chemistries: sequence-unspecific DNA labeling dyes (SYBR green), primer-based technologies (AmpliFluor, Plexor, Lux primers), and techniques involving double-labeled probes, comprising hybridization (molecular beacon) and hydrolysis (TaqMan, CPT, LNA, and MGB) probes, based on recently published experimental data. For each of the detection chemistries assays were included targeting selected loci. Real-time PCR chemistries were subsequently compared for their efficiency in PCR amplification and limits of detection and quantification. The overall applicability of the chemistries was evaluated, adding practicability and cost issues to the performance characteristics. None of the chemistries seemed to be significantly better than any other, but certain features favor LNA and MGB technology as good alternatives to TaqMan in quantification assays. SYBR green and molecular beacon assays can perform equally well but may need more optimization prior to use. PMID:20087729

  2. Stabilized, superparamagnetic functionalized graphene/Fe3O4@Au nanocomposites for a magnetically-controlled solid-state electrochemiluminescence biosensing application.

    PubMed

    Gu, Wenling; Deng, Xi; Gu, Xiaoxiao; Jia, Xiaofang; Lou, Baohua; Zhang, Xiaowei; Li, Jing; Wang, Erkang

    2015-02-01

    Herein, a multifunctional nanoarchitecture has been developed by integrating the branched poly(ethylenimine) functionalized graphene/iron oxide hybrids (BGNs/Fe3O4) and luminol capped gold nanoparticles (luminol-AuNPs). The luminescent luminol-AuNPs as an electrochemiluminescence marker can be assembled on the nanocarrier of BGNs/Fe3O4 hybrids efficiently via the Au-N chemical bonds and electrostatic adsorption. Meanwhile, the multifunctional nanoarchitecture has been proved with excellent electron transfer, good stability, high emission intensity, etc. Furthermore, we successfully developed an ultrasensitive magnetically-controlled solid-state electrochemiluminescence (ECL) platform for label-free determination of HeLa cells using this multifunctional nanocomposite. Excellent performance of the magnetically-controlled ECL biosensing platform has been achieved including a high sensitivity for HeLa cells with a linear range from 20 to 1 × 10(4) cells/mL, good stability, and reproducibility. PMID:25541634

  3. Au-Free GaN High-Electron-Mobility Transistor with Ti/Al/W Ohmic and WN X Schottky Metal Structures for High-Power Applications

    NASA Astrophysics Data System (ADS)

    Hsieh, Ting-En; Lin, Yueh-Chin; Chu, Chung-Ming; Chuang, Yu-Lin; Huang, Yu-Xiang; Shi, Wang-Cheng; Dee, Chang-Fu; Majlis, Burhanuddin Yeop; Lee, Wei-I.; Chang, Edward Yi

    2016-04-01

    In this study, an Au-free AlGaN/GaN high-electron-mobility transistor (HEMT) with Ti/Al/W ohmic and WNx Schottky metal structures is fabricated and characterized. The device exhibits smooth surface morphology after metallization and shows excellent direct-current (DC) characteristics. The device also demonstrates better performance than the conventional HEMTs under high voltage stress. Furthermore, the Au-free AlGaN/GaN HEMT shows stable device performance after annealing at 400°C. Thus, the Ti/Al/W ohmic and WN X Schottky metals can be applied in the manufacturing of GaN HEMT to replace the Au based contacts to reduce the manufacturing costs of the GaN HEMT devices with comparable device performance.

  4. Au-Free GaN High-Electron-Mobility Transistor with Ti/Al/W Ohmic and WN X Schottky Metal Structures for High-Power Applications

    NASA Astrophysics Data System (ADS)

    Hsieh, Ting-En; Lin, Yueh-Chin; Chu, Chung-Ming; Chuang, Yu-Lin; Huang, Yu-Xiang; Shi, Wang-Cheng; Dee, Chang-Fu; Majlis, Burhanuddin Yeop; Lee, Wei-I.; Chang, Edward Yi

    2016-07-01

    In this study, an Au-free AlGaN/GaN high-electron-mobility transistor (HEMT) with Ti/Al/W ohmic and WN x Schottky metal structures is fabricated and characterized. The device exhibits smooth surface morphology after metallization and shows excellent direct-current (DC) characteristics. The device also demonstrates better performance than the conventional HEMTs under high voltage stress. Furthermore, the Au-free AlGaN/GaN HEMT shows stable device performance after annealing at 400°C. Thus, the Ti/Al/W ohmic and WN X Schottky metals can be applied in the manufacturing of GaN HEMT to replace the Au based contacts to reduce the manufacturing costs of the GaN HEMT devices with comparable device performance.

  5. Preparation and Characterization of Au-ZrO2-SiO2 Nanocomposite Spheres and Their Application in Enrichment and Detection of Organophosphorus Agents

    SciTech Connect

    Yang, Yuqi; Tu, Haiyang; Zhang, Aidong; Du, Dan; Lin, Yuehe

    2012-03-01

    Au-ZrO{sub 2}-SiO{sub 2} nanocomposite spheres were synthesized and used as selective sorbents for the solid-phase extraction (SPE) of orananophosphorous agents. A non-enzymatic electrochemical sensor based on an Au-ZrO{sub 2}-SiO{sub 2} modified electrode was developed for selective detection of orananophosphorous pesticides (OPs). The Au-ZrO{sub 2}-SiO{sub 2} nanocomposite spheres were synthesized by hydrolysis and condensation of zirconia n-butoxide (TBOZ) on the surface of SiO{sub 2} spheres and then introduction of gold nanoparticles on the surface. Transmission electron microscope and X-ray photoelectron spectroscopy were performed to characterize the formation of the nanocomposite sphere. Fast extraction of OP was achieved by Au-ZrO{sub 2}-SiO{sub 2} modified electrode within 5 min via the specific affinity between zirconia and phosphoric group. The assay yields a broad concentration range of paraoxon-ethyl from 1.0 to 500 ng/mL{sup -1} with a detection limit 0.5 ng/mL{sup -1}. This selective and sensitive method holds great promise for the enrichment and detection of OPs.

  6. The synthesis of Au@C@Pt core-double shell nanocomposite and its application in enzyme-free hydrogen peroxide sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Yayun; Li, Yuhui; Jiang, Yingying; Li, Yancai; Li, Shunxing

    2016-08-01

    A novel Au@C@Pt core-double shell nanocomposite was synthesized and used to fabricate enzyme-free electrochemical sensor for rapid and sensitive detection of hydrogen peroxide (H2O2). The well-designed Au@C@Pt core-double shell nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy-dispersed spectrum (EDS). The Au@C@Pt core-double shell nanocomposite modified glassy carbon electrode (Au@C@Pt/GCE) exhibits good electrocatalytic activity towards H2O2 reduction at 0.0 V and can be used as H2O2 sensor. The sensor displays two wide linear ranges towards H2O2 detection. The one is 9.0 μM-1.86 mM with high sensitivity of 144.7 μA mM-1 cm-2, and the other is 1.86 mM-7.11 mM with sensitivity of 80.1 μA mM-1 cm-2. When signal to noise (S/N) is 3, the calculated detection limit (LOD) is 0.13 μM. Furthermore, the interference from the common interfering species such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided to H2O2 detection. Additionally, the H2O2 sensor also displays good stability and reproducibility.

  7. Bioinspired polydopamine as the scaffold for the active AuNPs anchoring and the chemical simultaneously reduced graphene oxide: characterization and the enhanced biosensing application.

    PubMed

    Tian, Juan; Deng, Sheng-Yuan; Li, Da-Li; Shan, Dan; He, Wei; Zhang, Xue-Ji; Shi, You

    2013-11-15

    We report here an efficient approach to enhance the performance of biosensing platform based on graphene or graphene derivate. Initially, graphene oxides (GO) nanosheets were reduced and surface functionalized by one-step oxidative polymerization of dopamine in basic solution at environment friendly condition to obtain the polydopamine (Pdop) modified reduced graphene oxides (PDRGO). The bioinspired surface was further used as a support to anchor active gold nanoparticles (AuNPs). The morphology and structure of the as-prepared AuNPs/PDRGO nanocomposite were investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR). Electrochemical studies demonstrate that the as-prepared AuNPs/PDRGO hybrid materials possess excellent electrochemical properties and electrocatalytic activity toward the oxidation of NADH at low potential (0.1 V vs. SCE) with the fast response (15s) and the broad linear range (5.0 × 10(-8)-4.2 × 10(-5)M). Thus, this AuNPs/PDRGO nanocomposite can be further used to fabricate a sensitive alcohol biosensor using alcohol dehydrogenase (ADH), by simply incorporating the specific enzyme within the composite matrix with the aid of chitosan (Chit). PMID:23811480

  8. A collection of research reporting, theoretical analysis, and practical applications in science education: Examining qualitative research methods, action research, educator-researcher partnerships, and constructivist learning theory

    NASA Astrophysics Data System (ADS)

    Hartle, R. Todd

    2007-12-01

    Educator-researcher partnerships are increasingly being used to improve the teaching of science. Chapter 1 provides a summary of the literature concerning partnerships, and examines the justification of qualitative methods in studying these relationships. It also justifies the use of Participatory Action Research (PAR). Empirically-based studies of educator-researcher partnership relationships are rare despite investments in their implementation by the National Science Foundation (NSF) and others. Chapter 2 describes a qualitative research project in which participants in an NSF GK-12 fellowship program were studied using informal observations, focus groups, personal interviews, and journals to identify and characterize the cultural factors that influenced the relationships between the educators and researchers. These factors were organized into ten critical axes encompassing a range of attitudes, behaviors, or values defined by two stereotypical extremes. These axes were: (1) Task Dictates Context vs. Context Dictates Task; (2) Introspection vs. Extroversion; (3) Internal vs. External Source of Success; (4) Prior Planning vs. Implementation Flexibility; (5) Flexible vs. Rigid Time Sense; (6) Focused Time vs. Multi-tasking; (7) Specific Details vs. General Ideas; (8) Critical Feedback vs. Encouragement; (9) Short Procedural vs. Long Content Repetition; and (10) Methods vs. Outcomes are Well Defined. Another ten important stereotypical characteristics, which did not fit the structure of an axis, were identified and characterized. The educator stereotypes were: (1) Rapport/Empathy; (2) Like Kids; (3) People Management; (4) Communication Skills; and (5) Entertaining. The researcher stereotypes were: (1) Community Collaboration; (2) Focus Intensity; (3) Persistent; (4) Pattern Seekers; and (5) Curiosity/Skeptical. Chapter 3 summarizes the research presented in chapter 2 into a practical guide for participants and administrators of educator-researcher partnerships

  9. Cu-Au, Ag-Au, Cu-Ag, and Ni-Au intermetallics: First-principles study of temperature-composition phase diagrams and structures

    NASA Astrophysics Data System (ADS)

    Ozoliņš, V.; Wolverton, C.; Zunger, Alex

    1998-03-01

    The classic metallurgical systems-noble-metal alloys-that have formed the benchmark for various alloy theories are revisited. First-principles fully relaxed general-potential linearized augmented plane-wave (LAPW) total energies of a few ordered structures are used as input to a mixed-space cluster expansion calculation to study the phase stability, thermodynamic properties, and bond lengths in Cu-Au, Ag-Au, Cu-Ag, and Ni-Au alloys. (i) Our theoretical calculations correctly reproduce the tendencies of Ag-Au and Cu-Au to form compounds and Ni-Au and Cu-Ag to phase separate at T=0 K. (ii) Of all possible structures, Cu3Au (L12) and CuAu (L10) are found to be the most stable low-temperature phases of Cu1-xAux with transition temperatures of 530 K and 660 K, respectively, compared to the experimental values 663 K and ~670 K. The significant improvement over previous first-principles studies is attributed to the more accurate treatment of atomic relaxations in the present work. (iii) LAPW formation enthalpies demonstrate that L12, the commonly assumed stable phase of CuAu3, is not the ground state for Au-rich alloys, but rather that ordered (100) superlattices are stabilized. (iv) We extract the nonconfigurational (e.g., vibrational) entropies of formation and obtain large values for the size-mismatched systems: 0.48 kB/atom in Ni0.5Au0.5 (T=1100 K), 0.37 kB/atom in Cu0.141Ag0.859 (T=1052 K), and 0.16 kB/atom in Cu0.5Au0.5 (T=800 K). (v) Using 8 atom/cell special quasirandom structures we study the bond lengths in disordered Cu-Au and Ni-Au alloys and obtain good qualitative agreement with recent extended x-ray-absorption fine-structure measurements.

  10. Tunable VO2/Au hyperbolic metamaterial

    NASA Astrophysics Data System (ADS)

    Prayakarao, S.; Mendoza, B.; Devine, A.; Kyaw, C.; van Dover, R. B.; Liberman, V.; Noginov, M. A.

    2016-08-01

    Vanadium dioxide (VO2) is known to have a semiconductor-to-metal phase transition at ˜68 °C. Therefore, it can be used as a tunable component of an active metamaterial. The lamellar metamaterial studied in this work is composed of subwavelength VO2 and Au layers and is designed to undergo a temperature controlled transition from the optical hyperbolic phase to the metallic phase. VO2 films and VO2/Au lamellar metamaterial stacks have been fabricated and studied in electrical conductivity and optical (transmission and reflection) experiments. The observed temperature-dependent changes in the reflection and transmission spectra of the metamaterials and VO2 thin films are in a good qualitative agreement with theoretical predictions. The demonstrated optical hyperbolic-to-metallic phase transition is a unique physical phenomenon with the potential to enable advanced control of light-matter interactions.

  11. Qualitative Student Models.

    ERIC Educational Resources Information Center

    Clancey, William J.

    The concept of a qualitative model is used as the focus of this review of qualitative student models in order to compare alternative computational models and to contrast domain requirements. The report is divided into eight sections: (1) Origins and Goals (adaptive instruction, qualitative models of processes, components of an artificial…

  12. Effectively Communicating Qualitative Research

    ERIC Educational Resources Information Center

    Ponterotto, Joseph G.; Grieger, Ingrid

    2007-01-01

    This article is a guide for counseling researchers wishing to communicate the methods and results of their qualitative research to varied audiences. The authors posit that the first step in effectively communicating qualitative research is the development of strong qualitative research skills. To this end, the authors review a process model for…

  13. Requiem for Qualitative Analysis.

    ERIC Educational Resources Information Center

    Journal of Chemical Education, 1983

    1983-01-01

    Five papers presented at the Seventh Biennial Conference on Chemical Education (Stillwater, Oklahoma 1982) focused on qualitative analysis curricula and instruction. Topics included benefits of qualitative analysis, use of iodo/bromo-complexes in qualitative analysis schemes, lecture demonstrations, and brief descriptions of three courses. (JN)

  14. Qualitative methods for assessing risk

    SciTech Connect

    Mahn, J.A.; Hannaman, G.W.; Kryska, P.

    1995-03-01

    The purpose of this document is to describe a qualitative risk assessment process that supplements the requirements of DOE/AL 5481.1B. Although facility managers have a choice of assessing risk either quantitatively or qualitatively, trade offs are involved in making the most appropriate choice for a given application. The results that can be obtained from a quantitative risk assessment are significantly more robust than those results derived from a qualitative approach. However, the advantages derived from quantitative risk assessment are achieved at a greater expenditure of money, time and convenience. This document provides the elements of a framework for performing a much less costly qualitative risk assessment, while retaining the best attributes of quantitative methods. The approach discussed herein will; (1) provide facility managers with the tools to prepare consistent, site wide assessments, and (2) aid the reviewers who may be tasked to evaluate the assessments. Added cost/benefit measures of the qualitative methodology include the identification of mechanisms for optimally allocating resources for minimizing risk in an expeditious, and fiscally responsible manner.

  15. Au transport in catalyst coarsening and Si nanowire formation.

    PubMed

    Kim, B J; Tersoff, J; Kodambaka, S; Jang, Ja-Soon; Stach, E A; Ross, F M

    2014-08-13

    The motion of Au between AuSi liquid eutectic droplets, both before and during vapor-liquid-solid growth, is important in controlling tapering and diameter uniformity in Si nanowires. We measure the kinetics of coarsening of AuSi droplets on Si(001) and Si(111), quantifying the size evolution of droplets during annealing in ultrahigh vacuum using in situ transmission electron microscopy. For individual droplets, we show that coarsening kinetics are modified when disilane or oxygen is added: coarsening rates increase in the presence of disilane but decrease in oxygen. Matching droplet size measurements on Si(001) with coarsening models confirms that Au transport is driven by capillary forces and that the kinetic coefficients depend on the gas environment present. We suggest that the gas effects are qualitatively similar whether transport is attachment limited or diffusion limited. These results provide insight into manipulating nanowire morphologies for advanced device fabrication. PMID:25040757

  16. The study on the application of solid-state method for synthesizing the polyaniline/noble metal (Au or Pt) hybrid materials.

    PubMed

    Jamal, Ruxangul; Xu, Feng; Shao, Weiwei; Abdiryim, Tursun

    2013-01-01

    The solid-state method was applied for synthesizing polyaniline (PANI)/noble metal hybrid materials with the presence of HAuCl4·4H2O or H2PtCl6·6H2O in the reaction medium. The structure, morphology, and electrochemical activity of the composites were characterized by Fourier transform infrared (FTIR) spectra, UV-visible (vis) absorption spectra, energy dispersive spectrum (EDS), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cyclic voltammetry. The results from FTIR and UV-vis spectra showed that the oxidation degree and doping level of the PANI in composites can be influenced by HAuCl4·4H2O and H2PtCl6·6H2O. The EDS data demonstrated that the composites contain a certain amount of Au (or Pt) element. XRD analysis indicated the presence of crystalline-state Au particles in PANI matrix prepared from the presence of HAuCl4·4H2O and revealed that the H2PtCl6·6H2O cannot be converted into metal Pt. The TEM and SEM images implied that the Au particles did exist in the polymer matrix with the size of about 20 nm. The enzymeless H2O2 sensor constructed with PANI/Au composite from the presence of HAuCl4·4H2O showed a short response time (within 5 s) and displayed an excellent performance in wide linear range. PMID:23452667

  17. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures.

    PubMed

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S; Weidner, Donald J

    2016-01-01

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K-B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10-15 μm) has been achieved at energies of 66 and 81 keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DAC can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. The coupling of sagittally bent Laue crystals with K-B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source. PMID:26902122

  18. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

    PubMed Central

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S.; Weidner, Donald J.

    2016-01-01

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K–B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10–15 μm) has been achieved at energies of 66 and 81 keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DAC can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. The coupling of sagittally bent Laue crystals with K–B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source. PMID:26902122

  19. Codetermination of crystal structures at high pressure: Combined application of theory and experiment to the intermetallic compound AuGa2

    NASA Astrophysics Data System (ADS)

    Godwal, B. K.; Stackhouse, S.; Yan, J.; Speziale, S.; Militzer, Burkhard; Jeanloz, R.

    2013-03-01

    A combination of x-ray diffraction at high pressures and first-principles calculations reveals the sequence of crystal-structural phase transitions in AuGa2 from cubic (Fm3¯m) to orthorhombic (Pnma) at 10 (±4) GPa and then to monoclinic (P21/n) at 33 (±6) GPa. Neither theory nor experiment would have been adequate, on their own, in documenting this sequence of phases, but together they confirm a sequence differing from the Fm3¯m→Pnma→P63/mmc transitions predicted for CaF2 and Pnma → P1121/a transition reported for PbCl2 and SnCl2. The combined results from theory and experiment also allow us to constrain the equations of state of the three phases of AuGa2. Calculations on the analog PbCl2 predict a transition to the P21/n phase seen in AuGa2 that could, therefore, be a common high-pressure phase for PbCl2-structured compounds.

  20. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

    NASA Astrophysics Data System (ADS)

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S.; Weidner, Donald J.

    2016-02-01

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K-B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10-15 μm) has been achieved at energies of 66 and 81 keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DAC can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. The coupling of sagittally bent Laue crystals with K-B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source.

  1. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

    DOE PAGESBeta

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S.; Weidner, Donald J.

    2016-02-23

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K–B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10–15 μm) has been achieved at energies of 66 and 81keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DACmore » can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. In conclusion, the coupling of sagittally bent Laue crystals with K–B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source.« less

  2. Green synthesis, characterization of Au-Ag core-shell nanoparticles using gripe water and their applications in nonlinear optics and surface enhanced Raman studies

    NASA Astrophysics Data System (ADS)

    Kirubha, E.; Palanisamy, P. K.

    2014-12-01

    In recent years there has been excessive progress in the ‘green’ chemistry approach for the synthesis of gold and silver nanoparticles. Bimetallic nanoparticles have gained special significance due to their unique tunable optical properties. Herein we report a facile one-pot, eco-friendly synthesis of Au-Ag bimetallic core-shell nanoparticles using gripe water as reducing as well as stabilizing agent. The as-synthesized Au-Ag nanoparticles are characterized using UV-Vis spectroscopy to determine the surface plasmon resonance, and using transmission electron microscopy to study the morphology and the particle size. The optical nonlinearity of the bimetallic nanoparticles investigated by z-scan technique using femtosecond Ti:sapphire is in the order of 109. The nonlinear optical parameters such as the nonlinear refractive index n2, nonlinear absorption coefficient β and the third order nonlinear susceptibility χ3 are measured for various wavelengths from 700 nm to 950 nm. The Au-Ag nanoparticles are also used in surface enhanced Raman spectroscopic studies to enhance the Raman signals of rhodamine 6G.

  3. The Vital Function of Fe3O4@Au nanocomposites for Hydrolase Biosensor Design and Its Application in Detection of Methyl Parathion

    SciTech Connect

    Zhao, Yuting; Zhang, Weiying; Lin, Yuehe; Du, Dan

    2013-02-04

    A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic Fe3O4 core was synthesized using cysteamine (SH–NH2) as linker, and characterized by TEM, XPS, UV and electrochemistry. Then a hydrolase biosensor, based on self-assembly of methyl parathion hydrolase (MPH) on the Fe3O4@Au nanocomposite, was developed for sensitive and selective detection of the organophosphorus pesticide (OP) methyl parathion. The magnetic nanocomposite provides an easy way to construct the enzyme biosensor by simply exerting an external magnetic field, and also provides a simple way to renew the electrode surface by removing the magnet. Unlike inhibition-based enzyme biosensors, the hydrolase is not poisoned by OPs and thus is reusable for continuous measurement. AuNPs not only provide a large surface area, high loading efficiency and fast electron transfer, but also stabilize the enzyme through electrostatic interactions. The MPH biosensor shows rapid response and high selectivity for detection of methyl parathion, with a linear range from 0.5 to 1000 ng/mL and a detection limit of 0.1 ng/mL. It also shows acceptable reproducibility and stability. The simplicity and ease of operation of the proposed method has great potential for on-site detection of P–S containing pesticides and provides a promising strategy to construct a robust biosensor.

  4. Growth of Long Range Forward-Backward Multiplicity Correlations with Centrality in Au+Au Collisions at sqrt sNN = 200 GeV

    SciTech Connect

    STAR Collaboration; Abelev, Betty

    2010-07-05

    Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV. Strong short and long range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short range correlations are observed in peripheral Au+Au collisions. Both the Dual Parton Model (DPM) and the Color Glass Condensate (CGC) predict the existence of the long range correlations. In the DPM the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC longitudinal color flux tubes generate the LRC. The data is in qualitative agreement with the predictions from the DPM and indicates the presence of multiple parton interactions.

  5. Growth of Long Range Forward-Backward Multiplicity Correlations with Centrality in Au+Au Collisions at sNN=200GeV

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Biritz, B.; Bland, L. C.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bruna, E.; Bueltmann, S.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; Calderón de La Barca Sánchez, M.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Clarke, R. F.; Codrington, M. J. M.; Corliss, R.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; de Silva, L. C.; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; de Souza, R. Derradi; Didenko, L.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Edwards, W. R.; Efimov, L. G.; Elhalhuli, E.; Elnimr, M.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gaillard, L.; Gangadharan, D. R.; Ganti, M. S.; Garcia-Solis, E. J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Huang, H. Z.; Humanic, T. J.; Huo, L.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jena, C.; Jin, F.; Jones, C. L.; Jones, P. G.; Joseph, J.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kikola, D. P.; Kiryluk, J.; Kisiel, A.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kopytine, M.; Korsch, W.; Kotchenda, L.; Kouchpil, V.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Krus, M.; Kuhn, C.; Kumar, L.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lapointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lee, J. H.; Leight, W.; Levine, M. J.; Li, N.; Li, C.; Li, Y.; Lin, G.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Ma, G. L.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meschanin, A.; Milner, R.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Poskanzer, A. M.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Pujahari, P. R.; Putschke, J.; Raniwala, R.; Raniwala, S.; Redwine, R.; Reed, R.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S. S.; Shi, X.-H.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Symons, T. J. M.; de Toledo, A. Szanto; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tlusty, D.; Tokarev, M.; Tram, V. N.; Trattner, A. L.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; van Buren, G.; van Leeuwen, M.; Vander Molen, A. M.; Vanfossen, J. A., Jr.; Varma, R.; Vasconcelos, G. M. S.; Vasilevski, I. M.; Vasiliev, A. N.; Videbaek, F.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, J. S.; Wang, Q.; Wang, X.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C., Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xie, W.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yang, Y.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, S.; Zhang, W. M.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zuo, J. X.

    2009-10-01

    Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and p+p collisions at sNN=200GeV. Strong short- and long-range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short-range correlations are observed in peripheral Au+Au collisions. Both the dual parton model (DPM) and the color glass condensate (CGC) predict the existence of the long-range correlations. In the DPM, the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC, longitudinal color flux tubes generate the LRC. The data are in qualitative agreement with the predictions of the DPM and indicate the presence of multiple parton interactions.

  6. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates.

    PubMed

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-07-14

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. PMID:27315144

  7. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates

    NASA Astrophysics Data System (ADS)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-06-01

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications.We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03484e

  8. The vital function of Fe3O4@Au nanocomposites for hydrolase biosensor design and its application in detection of methyl parathion

    NASA Astrophysics Data System (ADS)

    Zhao, Yuting; Zhang, Weiying; Lin, Yuehe; Du, Dan

    2013-01-01

    A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic Fe3O4 core was synthesized using cysteamine (SH-NH2) as linker, and characterized by TEM, XPS, UV and electrochemistry. Then a hydrolase biosensor, based on self-assembly of methyl parathion hydrolase (MPH) on the Fe3O4@Au nanocomposite, was developed for sensitive and selective detection of the organophosphorus pesticide (OP) methyl parathion. The magnetic nanocomposite provides an easy way to construct the enzyme biosensor by simply exerting an external magnetic field, and also provides a simple way to renew the electrode surface by removing the magnet. Unlike inhibition-based enzyme biosensors, the hydrolase is not poisoned by OPs and thus is reusable for continuous measurement. AuNPs not only provide a large surface area, high loading efficiency and fast electron transfer, but also stabilize the enzyme through electrostatic interactions. The MPH biosensor shows rapid response and high selectivity for detection of methyl parathion, with a linear range from 0.5 to 1000 ng mL-1 and a detection limit of 0.1 ng mL-1. It also shows acceptable reproducibility and stability. The simplicity and ease of operation of the proposed method has great potential for on-site detection of P-S containing pesticides and provides a promising strategy to construct a robust biosensor.A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic Fe3O4 core was synthesized using cysteamine (SH-NH2) as linker, and characterized by TEM, XPS, UV and electrochemistry. Then a hydrolase biosensor, based on self-assembly of methyl parathion hydrolase (MPH) on the Fe3O4@Au nanocomposite, was developed for sensitive and selective detection of the organophosphorus pesticide (OP) methyl parathion. The magnetic nanocomposite provides an easy way to construct the enzyme biosensor by simply exerting an external magnetic field, and also provides a simple way to renew the electrode surface by removing the magnet. Unlike

  9. Perceptions of the feasibility and acceptability of a smartphone application for the treatment of binge eating disorders: Qualitative feedback from a user population and clinicians

    PubMed Central

    Goldstein, Stephanie P.; Manasse, Stephanie M.; Forman, Evan M.; Butryn, Meghan L.

    2016-01-01

    Background Binge eating, a major public health problem, is characterized by recurrent episodes of out-of-control eating in which an individual consumes an unusually large amount of food in a discrete time period. Limitations of existing treatments for binge eating (both in-person psychotherapy and guided self-help) indicate that smartphone applications (apps) may be an ideal alternative or enhancement. An app for binge eating could aid treatment dissemination, engagement, and/or compliance. However, no research to date has examined user perceptions of a therapeutic app for binge eating, which is critical for development. Objectives The purposes of the current study were to conceptualize a potential app for binge eating and obtain feedback regarding feasibility and acceptability from target users (i.e., individuals with binge eating) and clinicians specializing in the treatment of binge eating. Methods Our team conceptualized a smartphone app that contained self-help material, functions to monitor behavior, and provisions of in-the-moment interventions. We presented this app (e.g., feature explanations, mock screen shots) through phone interviews with clinicians who specialize in the treatment of binge eating (n=10), and focus groups with individuals experiencing binge eating (n=11). Participants were asked to discuss customization, user burden, terminology, attrition, data visualization, comprehensiveness, reminders, feasibility, acceptability, and perceived effectiveness of the proposed app. Thematic analyses were conducted from qualitative data (e.g., audio recordings and interview notes) obtained via the focus groups and interviews. Results Results indicated that our proposed app would be highly feasible and acceptable to users and clinicians, though concerns about the degree of personalization and customizability were noted. Conclusions The current study details highly specific feedback and ideas regarding essential app features from target users and clinicians

  10. Heatless synthesis of well dispersible Au nanoparticles using pectin biopolymer.

    PubMed

    Ahmed, Hanan B; Zahran, M K; Emam, Hossam E

    2016-10-01

    Due to its potency to utilize in enormous applications, preparation of nanogold is of interest. Moreover, getting of highly dispersed nanogold with small size is extremely needful in specific fields. Herein, Au nanocolloid was prepared using alkali catalyzed pectin biopolymer. Pectin was concurrently used as reductant for Au ions and stabilizer for the produced Au nanoparticles (AuNPs). Reducing sugars were evaluated in the colloidal solution reflecting the role alkali in catalytic degradation of pectin to produce much powerful reducing moieties. The obtained Au nanocolloid was monitored via changing in color, UV-visible spectral and transmission electron microscopy. Using of NaOH as strong alkali achieving rapid rate of degradation reaction, resulted in 0.45g/L reducing sugars from 0.2g/L pectin which produced AuNPs with mean size of 6.5nm. In case of Na2CO3 which attained slow degradation rate led to, slightly low reducing sugar content (0.41g/L), fabricated comparatively size of AuNPs (7.5nm). In both cases, well distributed AuNPs was obtained with suitable stabilization up to 5 months and Na2CO3 exhibited higher stability. The current successful method used to produce small sized AuNPs with high dispersion is an innovative, one-step, easily, costless, energy saving and eco-friendly method. PMID:27212212

  11. Reduction of graphene oxide by 100 MeV Au ion irradiation and its application as H2O2 sensor

    NASA Astrophysics Data System (ADS)

    Hareesh, K.; Joshi, R. P.; Shateesh, B.; Asokan, K.; Kanjilal, D.; Late, D. J.; Dahiwale, S. S.; Bhoraskar, V. N.; Haram, S. K.; Dhole, S. D.

    2015-09-01

    Graphene oxide (GO) synthesized from a modified Hummer’s method was reduced (referred, rGO) by using 100 MeV Au ion species and its response to the sense H2O2 was investigated. The changes in the atomic composition and structural properties of rGO after irradiation were studied using x-ray diffraction, Fourier transform infrared spectroscopy and x-ray photo-electron spectroscopy. These results suggested that the removal of the oxygen-containing functional groups and the improvement of the electrochemical performance of reduced graphene oxide (rGO) after ion irradiation. Raman spectroscopic results revealed the increase in the disorder parameter (I D/I G) after Au ion irradiation and also the formation of a large number of small sp2 domains due to the electronic energy loss of ion beam. The resultant rGO was investigated for H2O2 sensing using electrochemical techniques and it showed a good response.

  12. M\\TiO₂ (M=Au, Ag) transparent aqueous sols and its application on polymeric surface antibacterial post-treatment.

    PubMed

    Wu, Liangzhuan; Yu, Yuan; Song, Le; Zhi, Jinfang

    2015-05-15

    In this paper, we reported a simple and mild chemical method for synthesis of crystalline metal\\TiO2 (M=Au, Ag) transparent aqueous sols at low temperature (80°C). It should be found that the as-synthesized metal\\TiO2 sols could easily be coated on the flexible PET surfaces of the through the as-developed electroless-plating-like solution deposition (EPLSD) procedure. The as-prepared metal\\TiO2 sols and related flexible thin film were characterized by TEM, SEM, XRD, UV-vis, and FTIR analysis. The results showed that the Au and Ag nanoparticles can significantly improve the optical absorption properties of TiO2 due to the surface plasmon generated by the noble metal, which in turn enhanced the photo-induced antibacterial performance of the as-prepared metal\\TiO2 flexible film. Moreover, the photo-generated electrons could transfer between the metal and titanium dioxide under different irradiation (ultraviolet or visible light), which could significantly reduce the recombination of photo-induced electrons and holes, resulting in the better photo-induced antibacterial performance. Therefore, the EPLSD procedure may be used as a general polymeric surface antibacterial post-treatment procedure for preparing the metal\\TiO2 flexible film because of the noble metal enhanced antibacterial performance. PMID:25678155

  13. Novel photoswitchable dielectric properties on nanomaterials of electronic core-shell γ-FeOx@Au@fullerosomes for GHz frequency applications.

    PubMed

    Wang, Min; Su, Chefu; Yu, Tzuyang; Tan, Loon-Seng; Hu, Bin; Urbas, Augustine; Chiang, Long Y

    2016-03-28

    We unexpectedly observed a large amplification of the dielectric properties associated with the photoswitching effect and the new unusual phenomenon of delayed photoinduced capacitor-like (i.e. electric polarization) behavior at the interface on samples of three-layered core-shell (γ-FeOx@AuNP)@[C60(>DPAF-C9)](n)2 nanoparticles (NPs) in frequencies of 0.5-4.0 GHz. The detected relative dielectric constant amplification was initiated upon switching off the light followed by relaxation to give an excellent recyclability. These NPs having e(-)-polarizable fullerosomic structures located at the outer layer were fabricated from highly magnetic core-shell γ-FeOx@AuNPs. Surface-stabilized 2 in a core-shell structure was found to be capable of photoinducing the surface plasmonic resonance (SPR) effect by white LED light. The accumulated SPR energy was subsequently transferred to the partially bilayered C60(>DPAF-C9) fullerosomic membrane layer in a near-field (∼1.5 nm) region without producing radiation heat. Since the monostatic SAR signal is dielectric property-dependent, we used these measurements to provide evidence of derived reflectivity changes on a surface coated with 2 at 0.5-4.0 GHz upon illumination of LED white light. We found that a high, >99%, efficiency of response amplification in image amplitude can be achieved. PMID:26936772

  14. Structure of SiAu16: can a silicon atom be stabilized in a gold cage?

    PubMed

    Sun, Qiang; Wang, Qian; Chen, Gang; Jena, Puru

    2007-12-01

    Nanostructures of Au and Si as well as Au-Si hybrid structures are topics of great current interest from both scientific and technological points of view. Recent discovery of Au clusters having fullerene-like geometries and the possibility of endohedral complexes with Si atoms inside the Au cage opens new possibilities for designing Au-Si nanostructures. Using ab initio simulated annealing method we have examined the stability of Si-Au16 endohedral complex. Contrary to what we believed, we find that the endohedral configuration is metastable and the structure where Si atom binds to the exterior surface of the Au16 cage is the lowest energy structure. The bonding of Si to Au cluster mimics its behavior of that in bulk and liquid phase of Au. In addition, doping of Si in high concentration would cause fracture and embrittlement in gold nanostructures just as it does in the bulk phase. Covalent bonding between Au-Au and Au-Si is found to be a dominant feature in the stability of the Au-Si nanostructures. Our study provides insight that may be useful in fabricating hybrid Au-Si nanostructures for applications microelectronics, catalysis, biomedicine, and jewelry industry. PMID:18067374

  15. Stability, structural and electronic properties of benzene molecule adsorbed on free standing Au layer

    NASA Astrophysics Data System (ADS)

    Katoch, Neha; Kapoor, Pooja; Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.

    2016-05-01

    We report stability and electronic properties of benzene molecule adsorbed on the Au atomic layer within the framework of density function theory (DFT). Horizontal configuration of benzene on the top site of Au monolayer prefers energetically over other studied configurations. On the adsorption of benzene, the ballistic conductance of Au monolayer is found to decrease from 4G0 to 2G0 suggesting its applications for the fabrications of organic sensor devices based on the Au atomic layers.

  16. Application of Criteria-Referenced Assessment and Qualitative Feedback to Develop Foreign Language Speaking Skills in the Context of E-Teaching/Learning

    ERIC Educational Resources Information Center

    Vitiene, Nijole; Miciuliene, Rita

    2008-01-01

    Responsive information is one of the factors that determine the quality of higher education. The factor is especially important for eLearning where a direct communication between a lecturer and a student is replaced with a virtual one. How may a qualitative responsive information, in other words feedback (see the definitions of key words), help…

  17. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    SciTech Connect

    Ohno, S.; Shimakura, H.; Tahara, S.; Okada, T.

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  18. Teaching Qualitative Research

    ERIC Educational Resources Information Center

    Delyser, Dydia

    2008-01-01

    Explicitly qualitative research has never before been so popular in human geography, and this article hopes to encourage more graduate students and faculty members to undertake the teaching of qualitative geography. The article describes one such course for graduate students, highlighting its challenges and rewards, and focusing on exercises…

  19. Qualitative Studies: Historiographical Antecedents.

    ERIC Educational Resources Information Center

    Mills, Rilla Dean

    This paper provides an overview of qualitative studies' antecedents among historiographers and of the positivist tide which nearly engulfed them. Humans live by interpretations. The task of social science--the basic task of qualitative studies--is to study these interpretations so that we can better understand the meanings which people use to…

  20. Visualizing Qualitative Information

    ERIC Educational Resources Information Center

    Slone, Debra J.

    2009-01-01

    The abundance of qualitative data in today's society and the need to easily scrutinize, digest, and share this information calls for effective visualization and analysis tools. Yet, no existing qualitative tools have the analytic power, visual effectiveness, and universality of familiar quantitative instruments like bar charts, scatter-plots, and…

  1. Sampling in Qualitative Research

    PubMed Central

    LUBORSKY, MARK R.; RUBINSTEIN, ROBERT L.

    2011-01-01

    In gerontology the most recognized and elaborate discourse about sampling is generally thought to be in quantitative research associated with survey research and medical research. But sampling has long been a central concern in the social and humanistic inquiry, albeit in a different guise suited to the different goals. There is a need for more explicit discussion of qualitative sampling issues. This article will outline the guiding principles and rationales, features, and practices of sampling in qualitative research. It then describes common questions about sampling in qualitative research. In conclusion it proposes the concept of qualitative clarity as a set of principles (analogous to statistical power) to guide assessments of qualitative sampling in a particular study or proposal. PMID:22058580

  2. Electrochemistry of Au(II) and Au(III) pincer complexes: determination of the Au(II)-Au(II) bond energy.

    PubMed

    Dann, Thomas; Roşca, Dragoş-Adrian; Wright, Joseph A; Wildgoose, Gregory G; Bochmann, Manfred

    2013-10-01

    The bond energy of the unsupported Au-Au bond in the Au(ii) dimer [(C(∧)N(∧)C)Au]2 and the difference between Au(III)-OH and Au(III)-H bond enthalpies have been determined experimentally by electrochemical methods, with Au-OH and Au-H complexes showing unexpected differences in their reduction pathways, supported by DFT modelling. PMID:24051607

  3. The transport of gold and molybdenum through hydration in aqueous vapor and vapor-like fluids: Application to porphyry Au and Mo deposits

    NASA Astrophysics Data System (ADS)

    Hurtig, N. C.; Williams-Jones, A. E.

    2013-12-01

    The hypothesis that vapor is a viable medium for the transport of gold and molybdenum in ore forming magmatic-hydrothermal systems is supported by fluid inclusion data, analyses of volcanic gas condensates and the occurrence of metal-rich incrustations around fumaroles. Experiments have shown that hydration of metal species in water vapor is an essential factor in making such transport possible [1,2,3]. Indeed, hydration has been shown to increase concentrations of Au and Mo in the aqueous vapor phase by several orders of magnitude over those calculated using volatility data. Nevertheless metal concentrations determined experimentally in previous studies are substantially lower than those reported for vapor inclusions in magmatic hydrothermal systems, and are limited to one or two dominant hydrated metal species. To bridge this gap, we performed a series of new experiments extending the density-range to near critical vapor density, and intermediate-density in the case of supercritical fluids. Experiments were carried out in batch-type Ti autoclaves at temperatures between 300 and 500 °C and pressures up to 366 bar in HCl-bearing water vapor. Oxygen fugacity was buffered either by the assemblage MoO2/MoO3 or WO2/WO3 or graphite. Gold and molybdenum concentrations measured in the experimental condensates ranged from 0.9 ppb and 3 ppm in low-density vapor at 300 °C to 4.6 ppm and 481 ppm at 297 bar and 400 °C, respectively. The fugacity of both metals increased exponentially with increasing water fugacity, resulting in an increase in metal solubility between 1 and 3 orders of magnitude from the lowest pressures investigated. Curves representing the experimentally determined relationship between metal fugacity and fH2O were fitted to a step-wise hydration model to extract a set of logarithmic equilibrium constants for P and T extrapolation. We have used the above data to model Au and Mo mobilization in magmatic-hydrothermal vapor plumes. This modeling shows that the

  4. 15-µm-pitch Cu/Au interconnections relied on self-aligned low-temperature thermosonic flip-chip bonding technique for advanced chip stacking applications

    NASA Astrophysics Data System (ADS)

    Thanh Tung, Bui; Kato, Fumiki; Watanabe, Naoya; Nemoto, Shunsuke; Kikuchi, Katsuya; Aoyagi, Masahiro

    2014-01-01

    In this paper, we report the development of reliable fine-pitch micro bump interconnections that used a high-precision room-temperature bonding approach. The accuracy of the bonding process is improved by modifying conventional bump/planar-bonding-pad interconnections to form self-aligned micro bumps/truncated inverted pyramid (TIP) bonding pads, i.e., misalignment self-correction elements (MSCEs). Thermosonic flip-chip bonding (FCB) is utilized to form reliable bonds between these MSCEs at acceptable low temperatures. By applying the proposed bonding approach, the demonstration of fine-pitch Cu bump to Au bonding pad interconnects chip stacking has been realized. Microstructure analyses reveal that 15-µm-pitch micro bump joints are fabricated at room temperature.

  5. Novel photoswitchable dielectric properties on nanomaterials of electronic core-shell γ-FeOx@Au@fullerosomes for GHz frequency applications

    NASA Astrophysics Data System (ADS)

    Wang, Min; Su, Chefu; Yu, Tzuyang; Tan, Loon-Seng; Hu, Bin; Urbas, Augustine; Chiang, Long Y.

    2016-03-01

    We unexpectedly observed a large amplification of the dielectric properties associated with the photoswitching effect and the new unusual phenomenon of delayed photoinduced capacitor-like (i.e. electric polarization) behavior at the interface on samples of three-layered core-shell (γ-FeOx@AuNP)@[C60(>DPAF-C9)]n2 nanoparticles (NPs) in frequencies of 0.5-4.0 GHz. The detected relative dielectric constant amplification was initiated upon switching off the light followed by relaxation to give an excellent recyclability. These NPs having e--polarizable fullerosomic structures located at the outer layer were fabricated from highly magnetic core-shell γ-FeOx@AuNPs. Surface-stabilized 2 in a core-shell structure was found to be capable of photoinducing the surface plasmonic resonance (SPR) effect by white LED light. The accumulated SPR energy was subsequently transferred to the partially bilayered C60(>DPAF-C9) fullerosomic membrane layer in a near-field (~1.5 nm) region without producing radiation heat. Since the monostatic SAR signal is dielectric property-dependent, we used these measurements to provide evidence of derived reflectivity changes on a surface coated with 2 at 0.5-4.0 GHz upon illumination of LED white light. We found that a high, >99%, efficiency of response amplification in image amplitude can be achieved.We unexpectedly observed a large amplification of the dielectric properties associated with the photoswitching effect and the new unusual phenomenon of delayed photoinduced capacitor-like (i.e. electric polarization) behavior at the interface on samples of three-layered core-shell (γ-FeOx@AuNP)@[C60(>DPAF-C9)]n2 nanoparticles (NPs) in frequencies of 0.5-4.0 GHz. The detected relative dielectric constant amplification was initiated upon switching off the light followed by relaxation to give an excellent recyclability. These NPs having e--polarizable fullerosomic structures located at the outer layer were fabricated from highly magnetic core-shell γ-FeOx@Au

  6. Effect of Silicon on Activity Coefficients of Siderophile Elements (P, Au, Pd, As, Ge, Sb, and In) in Liquid Fe, with Application to Core Formation

    NASA Technical Reports Server (NTRS)

    Righter, K.; Pando, K.; Danielson, L. R.; Humayun, M.; Righter, M.; Lapen, T.; Boujibar, A.

    2016-01-01

    Earth's core contains approximately 10 percent light elements that are likely a combination of S, C, Si, and O, with Si possibly being the most abundant. Si dissolved into Fe liquids can have a large effect on the magnitude of the activity coefficient of siderophile elements (SE) in Fe liquids, and thus the partitioning behavior of those elements between core and mantle. The effect of Si can be small such as for Ni and Co, or large such as for Mo, Ge, Sb, As. The effect of Si on many siderophile elements is unknown yet could be an important, and as yet unquantified, influence on the core-mantle partitioning of SE. Here we report new experiments designed to quantify the effect of Si on the partitioning of P, Au, Pd, and many other SE between metal and silicate melt. The results will be applied to Earth, for which we have excellent constraints on the mantle siderophile element concentrations.

  7. Growth of GaN@InGaN Core-Shell and Au-GaN Hybrid Nanostructures for Energy Applications

    DOE PAGESBeta

    Kuykendall, Tevye; Aloni, Shaul; Jen-La Plante, Ilan; Mokari, Taleb

    2009-01-01

    We demonstrated a method to control the bandgap energy of GaN nanowires by forming GaN@InGaN core-shell hybrid structures using metal organic chemical vapor deposition (MOCVD). Furthermore, we show the growth of Au nanoparticles on the surface of GaN nanowires in solution at room temperature. The work shown here is a first step toward engineering properties that are crucial for the rational design and synthesis of a new class of photocatalytic materials. The hybrid structures were characterized by various techniques, including photoluminescence (PL), energy dispersive x-ray spectroscopy (EDS), transmission and scanning electron microscopy (TEM and SEM), and x-ray diffraction (XRD).

  8. Knowledge representation and qualitative simulation of salmon redd functioning. Part I: qualitative modeling and simulation.

    PubMed

    Guerrin, F; Dumas, J

    2001-02-01

    This work aims at representing empirical knowledge of freshwater ecologists on the functioning of salmon redds (spawning areas of salmon) and its impact on mortality of early stages. For this, we use Qsim, a qualitative simulator. In this first part, we provide unfamiliar readers with the underlying qualitative differential equation (QDE) ontology of Qsim: representing quantities, qualitative variables, qualitative constraints, QDE structure. Based on a very simple example taken of the salmon redd application, we show how informal biological knowledge may be represented and simulated using an approach that was first intended to analyze qualitatively ordinary differential equations systems. A companion paper (Part II) gives the full description and simulation of the salmon redd qualitative model. This work was part of a project aimed at assessing the impact of the environment on salmon populations dynamics by the use of models of processes acting at different levels: catchment, river, and redds. Only the latter level is dealt with in this paper. PMID:11267737

  9. Magnetoresistance of Au films

    DOE PAGESBeta

    Zhang, D. L.; Song, X. H.; Zhang, X.; Zhang, Xiaoguang

    2014-12-10

    Measurement of the magnetoresistance (MR) of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler s rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms.

  10. Magnetoresistance of Au films

    SciTech Connect

    Zhang, D. L.; Song, X. H.; Zhang, X; Zhang, Xiaoguang

    2014-01-01

    Measurement of the magnetoresistance (MR) of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler s rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms.

  11. Synthesis and electrocatalytic activity of Au/Pt bimetallic nanodendrites for ethanol oxidation in alkaline medium.

    PubMed

    Han, Xinyi; Wang, Dawei; Liu, Dong; Huang, Jianshe; You, Tianyan

    2012-02-01

    Gold/Platinum (Au/Pt) bimetallic nanodendrites were successfully synthesized through seeded growth method using preformed Au nanodendrites as seeds and ascorbic acid as reductant. Cyclic voltammograms (CVs) of a series of Au/Pt nanodendrites modified electrodes in 1M KOH solution containing 1M ethanol showed that the electrocatalyst with a molar ratio (Au:Pt) of 3 exhibited the highest peak current density and the lowest onset potential. The peak current density of ethanol electro-oxidation on the Au(3)Pt(1) nanodendrites modified glassy carbon electrode (Au(3)Pt(1) electrode) is about 16, 12.5, and 4.5 times higher than those on the polycrystalline Pt electrode, polycrystalline Au electrode, and Au nanodendrites modified glassy carbon electrode (Au dendrites electrode), respectively. The oxidation peak potential of ethanol electro-oxidation on the Au(3)Pt(1) electrode is about 299 and 276 mV lower than those on the polycrystalline Au electrode and Au dendrites electrode, respectively. These results demonstrated that the Au/Pt bimetallic nanodendrites may find potential application in alkaline direct ethanol fuel cells (ADEFCs). PMID:22071516

  12. HCG blood test - qualitative

    MedlinePlus

    ... qualitative Images Blood test References Lee P, Pincus MR, McPherson RA. Diagnosis and management of cancer using serologic tumor markers. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory ...

  13. Computers and Qualitative Research.

    ERIC Educational Resources Information Center

    Willis, Jerry; Jost, Muktha

    1999-01-01

    Discusses the use of computers in qualitative research, including sources of information; collaboration; electronic discussion groups; Web sites; Internet search engines; electronic sources of data; data collection; communicating research results; desktop publishing; hypermedia and multimedia documents; electronic publishing; holistic and…

  14. Qualitative model-based diagnosis using possibility theory

    NASA Technical Reports Server (NTRS)

    Joslyn, Cliff

    1994-01-01

    The potential for the use of possibility in the qualitative model-based diagnosis of spacecraft systems is described. The first sections of the paper briefly introduce the Model-Based Diagnostic (MBD) approach to spacecraft fault diagnosis; Qualitative Modeling (QM) methodologies; and the concepts of possibilistic modeling in the context of Generalized Information Theory (GIT). Then the necessary conditions for the applicability of possibilistic methods to qualitative MBD, and a number of potential directions for such an application, are described.

  15. Qualitative models for space system engineering

    NASA Technical Reports Server (NTRS)

    Forbus, Kenneth D.

    1990-01-01

    The objectives of this project were: (1) to investigate the implications of qualitative modeling techniques for problems arising in the monitoring, diagnosis, and design of Space Station subsystems and procedures; (2) to identify the issues involved in using qualitative models to enhance and automate engineering functions. These issues include representing operational criteria, fault models, alternate ontologies, and modeling continuous signals at a functional level of description; and (3) to develop a prototype collection of qualitative models for fluid and thermal systems commonly found in Space Station subsystems. Potential applications of qualitative modeling to space-systems engineering, including the notion of intelligent computer-aided engineering are summarized. Emphasis is given to determining which systems of the proposed Space Station provide the most leverage for study, given the current state of the art. Progress on using qualitative models, including development of the molecular collection ontology for reasoning about fluids, the interaction of qualitative and quantitative knowledge in analyzing thermodynamic cycles, and an experiment on building a natural language interface to qualitative reasoning is reported. Finally, some recommendations are made for future research.

  16. Dynamic features of rod-shaped Au nanoclusters

    NASA Astrophysics Data System (ADS)

    So, Woong Young; Das, Anindita; Wang, Shuxin; Zhao, Shuo; Byun, Hee Young; Lee, Dana; Kumar, Santosh; Jin, Rongchao; Peteanu, Linda A.

    2015-08-01

    Gold nanoclusters hold many potential applications such as biosensing and optics due to their emission characteristics, small size, and non-toxicity. However, their low quantum yields remain problematic for further applications, and their fluorescence mechanism is still unclear. To increase the low quantum yields, various methods have been performed: doping, tuning structures, and changing number of gold atoms. In the past, most characterizations have been performed on spherical shaped nanoclusters; in this paper, several characterizations of various rod-shaped Au nanoclusters specifically on Au25 are shown. It has been determined that the central gold atom in Au25 nano-rod is crucial in fluorescence. Furthermore, single molecule analysis of silver doped Au25 nano-rod revealed that it has more photo-stability than conjugated polymers and quantum dots.

  17. Antibacterial Au nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-01-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies.We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It

  18. Stream dynamics between 1 AU and 2 AU: A detailed comparison of observations and theory

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Pizzo, V.; Lazarus, A.; Gazis, P. R.

    1984-01-01

    A radial alignment of three solar wind stream structures observed by IMP-7 and -8 (at 1.0 AU) and Voyager 1 and 2 (in the range 1.4 to 1.8 AU) in late 1977 is presented. It is demonstrated that several important aspects of the observed dynamical evolution can be both qualitatively and quantitatively described with a single-fluid 2-D MHD numerical model of quasi-steady corotating flow, including accurate prediction of: (1) the formation of a corotating shock pair at 1.75 AU in the case of a simple, quasi-steady stream; (2) the coalescence of the thermodynamic and magnetic structures associated with the compression regions of two neighboring, interacting, corotating streams; and (3) the dynamical destruction of a small (i.e., low velocity-amplitude, short spatial-scale) stream by its overtaking of a slower moving, high-density region associated with a preceding transient flow. The evolution of these flow systems is discussed in terms of the concepts of filtering and entrainment.

  19. [Sb4Au4Sb4]2-: A designer all-metal aromatic sandwich

    NASA Astrophysics Data System (ADS)

    Tian, Wen-Juan; Guo, Jin-Chang; Li, Da-Zhi; You, Xue-Rui; Wang, Ying-Jin; Sun, Zhong-Ming; Zhai, Hua-Jin

    2016-07-01

    We report on the computational design of an all-metal aromatic sandwich, [Sb4Au4Sb4]2-. The triple-layered, square-prismatic sandwich complex is the global minimum of the system from Coalescence Kick and Minima Hopping structural searches. Following a standard, qualitative chemical bonding analysis via canonical molecular orbitals, the sandwich complex can be formally described as [Sb4]+[Au4]4-[Sb4]+, showing ionic bonding characters with electron transfers in between the Sb4/Au4/Sb4 layers. For an in-depth understanding of the system, one needs to go beyond the above picture. Significant Sb → Au donation and Sb ← Au back-donation occur, redistributing electrons from the Sb4/Au4/Sb4 layers to the interlayer Sb-Au-Sb edges, which effectively lead to four Sb-Au-Sb three-center two-electron bonds. The complex is a system with 30 valence electrons, excluding the Sb 5s and Au 5d lone-pairs. The two [Sb4]+ ligands constitute an unusual three-fold (π and σ) aromatic system with all 22 electrons being delocalized. An energy gap of ˜1.6 eV is predicted for this all-metal sandwich. The complex is a rare example for rational design of cluster compounds and invites forth-coming synthetic efforts.

  20. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Chaffin, Elise; O'Connor, Ryan T.; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ˜410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods.

  1. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles.

    PubMed

    Chaffin, Elise; O'Connor, Ryan T; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ∼410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods. PMID:27497571

  2. Surface morphology and optical properties of porphyrin/Au and Au/porphyrin/Au systems

    NASA Astrophysics Data System (ADS)

    Kalachyova, Yevgeniya; Lyutakov, Oleksiy; Solovyev, Andrey; Slepička, Petr; Švorčík, Vaclav

    2013-12-01

    Porphyrin/Au and Au/porphyrin/Au systems were prepared by vacuum evaporation and vacuum sputtering onto glass substrate. The surface morphology of as-prepared systems and those subjected to annealing at 160°C was studied by optical microscopy, atomic force microscopy, and scanning electron microscopy techniques. Absorption and luminescence spectra of as-prepared and annealed samples were measured. Annealing leads to disintegration of the initially continuous gold layer and formation of gold nanoclusters. An amplification of Soret band magnitude was observed on the Au/meso-tetraphenyl porphyrin (TPP) system in comparison with mere TPP. Additional enhancement of luminescence was observed after the sample annealing. In the case of sandwich Au/porphyrin/Au structure, suppression of one of the two porphyrins' luminescence maxima and sufficient enhancement of the second one were observed.

  3. Antibacterial Au nanostructured surfaces.

    PubMed

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-02-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies. PMID:26648134

  4. Comparison of photoluminescence properties of HSA-protected and BSA-protected Au25 nanoclusters

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Masato; Kawasaki, Hideya; Saitoh, Tadashi; Inada, Mitsuru; Kansai Univ. Collaboration

    Gold nanoclusters (NCs) have attracted great interest for a wide range of applications. In particular, red light-emitting Au25 NCs have been prepared with various biological ligands. It has been shown that Au25 NCs have Au13-core/6Au2(SR)3-semiring structure. The red luminescence thought to be originated from both core (670 nm) and semiring (625 nm). It is important to reveal a structure of Au25 NCs to facilitate the progress of applications. However, the precise structure of Au25 NCs has not been clarified. There is a possibility of obtaining structural information about Au25 NCs to compare optical properties of the NCs that protected by slightly different molecules. Bovine and human serum albumin (BSA, HSA) are suitable one for this purpose. It has been suggested that rich tyrosine and cysteine residues in these molecules are important to produce the thiolate-protected Au NCs. If Au25 NCs have core/shell structure, only the luminescence of the semiring will be affected by the difference of the albumin molecules. We carefully compared PL characteristics of BSA- and HSA- protected Au25 NCs. As a result, there was no difference in the PL at 670 nm (core), while differences were observed in the PL at 625 nm (semiring). The results support that Au25 NCs have core/semiring structure.

  5. Stepwise sensitivity analysis from qualitative to quantitative: Application to the terrestrial hydrological modeling of a Conjunctive Surface-Subsurface Process (CSSP) land surface model

    NASA Astrophysics Data System (ADS)

    Gan, Yanjun; Liang, Xin-Zhong; Duan, Qingyun; Choi, Hyun Il; Dai, Yongjiu; Wu, Huan

    2015-06-01

    An uncertainty quantification framework was employed to examine the sensitivities of 24 model parameters from a newly developed Conjunctive Surface-Subsurface Process (CSSP) land surface model (LSM). The sensitivity analysis (SA) was performed over 18 representative watersheds in the contiguous United States to examine the influence of model parameters in the simulation of terrestrial hydrological processes. Two normalized metrics, relative bias (RB) and Nash-Sutcliffe efficiency (NSE), were adopted to assess the fit between simulated and observed streamflow discharge (SD) and evapotranspiration (ET) for a 14 year period. SA was conducted using a multiobjective two-stage approach, in which the first stage was a qualitative SA using the Latin Hypercube-based One-At-a-Time (LH-OAT) screening, and the second stage was a quantitative SA using the Multivariate Adaptive Regression Splines (MARS)-based Sobol' sensitivity indices. This approach combines the merits of qualitative and quantitative global SA methods, and is effective and efficient for understanding and simplifying large, complex system models. Ten of the 24 parameters were identified as important across different watersheds. The contribution of each parameter to the total response variance was then quantified by Sobol' sensitivity indices. Generally, parameter interactions contribute the most to the response variance of the CSSP, and only 5 out of 24 parameters dominate model behavior. Four photosynthetic and respiratory parameters are shown to be influential to ET, whereas reference depth for saturated hydraulic conductivity is the most influential parameter for SD in most watersheds. Parameter sensitivity patterns mainly depend on hydroclimatic regime, as well as vegetation type and soil texture. This article was corrected on 26 JUN 2015. See the end of the full text for details.

  6. Studies of the structure and phase transitions of nano-confined pentanedithiol and its application in directing hierarchical molecular assemblies on Au(1 1 1)

    NASA Astrophysics Data System (ADS)

    Pawlicki, Alison; Avery, Erin; Jurow, Matthew; Ewers, Bradley; Vilan, Ayelet; Drain, Charles Michael; Batteas, James

    2016-03-01

    Directing molecular devices into pre-designed integrated electronic circuits while enforcing selectivity and hierarchy is an inherent challenge for molecular electronics. Here we explore ways to direct the assembly of electrically-active molecular monolayers into specific locations as well as controlling their internal organization. We have accomplished this by two consecutive surface reactions: (1) forming pentanedithiol (C5DT) domains within an inert alkanethiol self-assembled monolayer (SAM) on Au; and (2) selectively binding porphyrin derivatives to the C5DT domains. The C5DT domains were fabricated by phase segregation during co-adsorption from a mixed C5DT/dodecanethiol (C12) solution and nanografting with Atomic Force Microscopy (AFM). AFM revealed that co-absorbed and nanografted C5DT domains were in a standing-up phase and scanning tunneling microscopy (STM) showed that their molecular organization within about 5 nm, 40 nm, 50 nm and 120 nm domains, was dependent upon the size of the domain, such that structure of the C5DT transitions from (\\sqrt{3}   ×  \\sqrt{3} ) R30°, to (2  ×  2), and ultimately to a disordered phase with increasing domain size. This is due to the varying degrees of influence of the surrounding C12; providing sufficient van der Waals interactions as well as a geometric confinement to stabilize the standing-up phase of the C5DT. Understanding the molecular configuration of dithiol SAMs affords their use as a reactive template to subsequently bind active head groups. As a proof of principle, porphyrins with a pendant pentafluorophenyl ring were attached to the C5DT domains by a ‘click’ reaction between the fluorinated ring and the free thiol on the surface. From AFM and STM, these porphyrin derivatives reacted selectively with the C5DT domains with some porphyrins binding directly to the C5DT, subsequently allowing additional localized porphyrin deposition through pi-stacking.

  7. Qualitative Assertions as Prescriptive Statements

    ERIC Educational Resources Information Center

    Nolen, Amanda; Talbert, Tony

    2011-01-01

    The primary question regarding prescriptive appropriateness is a difficult one to answer for the qualitative researcher. While there are certainly qualitative researchers who have offered prescriptive protocols to better define and describe the terrain of qualitative research design and there are qualitative researchers who offer research…

  8. Demystifying Interdisciplinary Qualitative Research

    ERIC Educational Resources Information Center

    Greckhamer, Thomas; Koro-Ljungberg, Mirka; Cilesiz, Sebnem; Hayes, Sharon

    2008-01-01

    This article seeks to demystify, through deconstruction, the concept of "interdisciplinarity" in the context of qualitative research to contribute to a new praxis of knowledge production through reflection on the possibilities and impossibilities of interdisciplinarity. A review and discussion of disciplinarity and interdisciplinarity leads the…

  9. [Qualitative case study].

    PubMed

    Debout, Christophe

    2016-06-01

    The qualitative case study is a research method which enables a complex phenomenon to be explored through the identification of different factors interacting with each other. The case observed is a real situation. In the field of nursing science, it may be a clinical decision-making process. The study thereby enables the patient or health professional experience to be conceptualised. PMID:27338694

  10. Disciplining Qualitative Research

    ERIC Educational Resources Information Center

    Denzin, Norman K.; Lincoln, Yvonna S.; Giardina, Michael D.

    2006-01-01

    Qualitative research exists in a time of global uncertainty. Around the world, governments are attempting to regulate scientific inquiry by defining what counts as "good" science. These regulatory activities raise fundamental, philosophical epistemological, political and pedagogical issues for scholarship and freedom of speech in the academy. This…

  11. Entropy Is Simple, Qualitatively.

    ERIC Educational Resources Information Center

    Lambert, Frank L.

    2002-01-01

    Suggests that qualitatively, entropy is simple. Entropy increase from a macro viewpoint is a measure of the dispersal of energy from localized to spread out at a temperature T. Fundamentally based on statistical and quantum mechanics, this approach is superior to the non-fundamental "disorder" as a descriptor of entropy change. (MM)

  12. The Qualitative Similarity Hypothesis

    ERIC Educational Resources Information Center

    Paul, Peter V.; Lee, Chongmin

    2010-01-01

    Evidence is presented for the qualitative similarity hypothesis (QSH) with respect to children and adolescents who are d/Deaf or hard of hearing. The primary focus is on the development of English language and literacy skills, and some information is provided on the acquisition of English as a second language. The QSH is briefly discussed within…

  13. Bookstart: A Qualitative Evaluation.

    ERIC Educational Resources Information Center

    Moore, Maggie; Wade, Barrie

    2003-01-01

    A qualitative study of Bookstart, which gave free children's books and support to British inner-city families, collected data from librarians, health visitors, and nursery school staff. Bookstart increased positive attitudes toward and interest in books. Health visitors' support was crucial in helping parents use the books to support children's…

  14. Significant Broadband Photocurrent Enhancement by Au-CZTS Core-Shell Nanostructured Photocathodes

    NASA Astrophysics Data System (ADS)

    Zhang, Xuemei; Wu, Xu; Centeno, Anthony; Ryan, Mary P.; Alford, Neil M.; Riley, D. Jason; Xie, Fang

    2016-03-01

    Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.

  15. Propagating Qualitative Values Through Quantitative Equations

    NASA Technical Reports Server (NTRS)

    Kulkarni, Deepak

    1992-01-01

    In most practical problems where traditional numeric simulation is not adequate, one need to reason about a system with both qualitative and quantitative equations. In this paper, we address the problem of propagating qualitative values represented as interval values through quantitative equations. Previous research has produced exponential-time algorithms for approximate solution of the problem. These may not meet the stringent requirements of many real time applications. This paper advances the state of art by producing a linear-time algorithm that can propagate a qualitative value through a class of complex quantitative equations exactly and through arbitrary algebraic expressions approximately. The algorithm was found applicable to Space Shuttle Reaction Control System model.

  16. A Quantitative Assessment of the Size-Frequency Distribution of Terrestrial Dust Devils, Comparison with Qualitative Estimates, and Applications to Mars

    NASA Astrophysics Data System (ADS)

    Pathare, A.; Balme, M. R.; Metzger, S.; Towner, M.; Spiga, A.; Renno, N. O.; Elliott, H. M.; Russell, P. S.; Fenton, L. K.; Michaels, T. I.

    2011-12-01

    Dust devils are particle-loaded vertical convective vortices commonly observed on Earth and especially Mars. Qualitative estimates of terrestrial dust devil frequency based upon visual field surveys have varied by several orders of magnitude. We will present the results of our quantitative characterization of the size-frequency distribution (SFD) of terrestrial dust devils, which utilizes stereo photography to calculate dust devil diameters via parallax displacement. In 2009, we conducted field campaigns in Eloy, Arizona and Eldorado Valley, Nevada to survey terrestrial dust devils: the latter site was revisited in 2010. During each survey period, at least two and usually three observers were positioned at spotter stations located approximately 100 m apart, thereby allowing triangular study areas (bounded by three meteorological masts) of A = 0.83 sq. km and A = 0.55 sq. km to be surveyed in Eloy and Eldorado Valley, respectively. Each spotter station was equipped with a tripod-mounted, weatherproof digital camera: whenever possible, any dust devils observed within the study area were photographed simultaneously by camera operators in radio contact. All dust devils observed within the survey sites were assigned a qualitative diameter estimate (i.e., Tiny/Small/Medium/Large) by a third spotter positioned near the center of the study area. Thus even if small dust devils occurred that existed too fleetingly to be photographed, they were still recorded. Methodology: The positions of both survey tripods were measured to ~ 0.5 m precision using GPS. In addition, a full 360-degree panorama was generated from each survey position, corrected for lens distortion, and then imported into a GIS. The photographs of dust devils from each camera are then also incorporated into the GIS and aligned against the corresponding background panorama. The width and center points of each dust devil are then digitized and its bearings and angular width outputted from the GIS, together with

  17. Enhanced strange baryon production in Au+Au collisions compared to p+p at {radical}{ovr s}{sub NN} = 200 GeV.

    SciTech Connect

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Krueger, K.; Spinka, H. M.; Underwood, D. G.; STAR Collaboration; McClain, C. J.; High Energy Physics; Univ. of Illinois; Panjab Univ.; Variable Energy Cyclotron Centre; Kent State Univ.; Particle Physic Lab.

    2008-01-01

    We report on the observed differences in production rates of strange and multistrange baryons in Au+Au collisions at {radical}s{sub NN} = 200 GeV compared to p+p interactions at the same energy. The strange baryon yields in Au+Au collisions, when scaled down by the number of participating nucleons, are enhanced relative to those measured in p+p reactions. The enhancement observed increases with the strangeness content of the baryon, and it increases for all strange baryons with collision centrality. The enhancement is qualitatively similar to that observed at the lower collision energy {radical}s{sub NN} = 17.3 GeV. The previous observations are for the bulk production, while at intermediate p{sub T},1 < p{sub T} < 4 GeV/c, the strange baryons even exceed binary scaling from p+p yields.

  18. Enhanced strange baryon production in Au+Au collisions compared to p+p at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betts, R. R.; Bhardwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Blyth, S.-L.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bueltmann, S.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Callner, J.; Catu, O.; Cebra, D.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Chung, S. U.; Clarke, R. F.; Codrington, M. J. M.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; Moura, M. M. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Souza, R. Derradi De; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Edwards, W. R.; Efimov, L. G.; Elhalhuli, E.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Ganti, M. S.; Garcia-Solis, E.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. G.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Henry, T. W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Horner, M. J.; Huang, H. Z.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jin, F.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kiryluk, J.; Kisiel, A.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kowalik, K. L.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kumar, A.; Kumar, L.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lapointe, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Levine, M. J.; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lin, X.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meschanin, A.; Millane, J.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Nepali, C.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Pal, S. K.; Panebratsev, Y.; Pavlinov, A. I.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Porile, N.; Poskanzer, A. M.; Potekhin, M.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Putschke, J.; Qattan, I. A.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Relyea, D.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Rykov, V.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, X.-H.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Toledo, A. Szanto De; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Trainor, T. A.; Tram, V. N.; Trattner, A. L.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Kolk, N. Van Der; Leeuwen, M. Van; Molen, A. M. Vander; Varma, R.; Vasconcelos, G. M. S.; Vasilevski, I. M.; Vasiliev, A. N.; Vernet, R.; Videbaek, F.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, Q.; Wang, X.; Wang, X. L.; Wang, Y.; Webb, J. C.; Westfall, G. D.; , C. Whitten, Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, J.; Wu, Y.; Xu, N.; Xu, Q. H.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, H.; Zhang, S.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zuo, J. X.

    2008-04-01

    We report on the observed differences in production rates of strange and multistrange baryons in Au+Au collisions at sNN=200 GeV compared to p+p interactions at the same energy. The strange baryon yields in Au+Au collisions, when scaled down by the number of participating nucleons, are enhanced relative to those measured in p+p reactions. The enhancement observed increases with the strangeness content of the baryon, and it increases for all strange baryons with collision centrality. The enhancement is qualitatively similar to that observed at the lower collision energy sNN=17.3 GeV. The previous observations are for the bulk production, while at intermediate pT,1

  19. Synthesis of Au@Pt bimetallic nanoparticles with concave Au nanocuboids as seeds and their enhanced electrocatalytic properties in the ethanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Tan, Lingyu; Li, Lidong; Peng, Yi; Guo, Lin

    2015-12-01

    Herein, a new type of uniform and well-structured Au@Pt bimetallic nanoparticles (BNPs) with highly active concave Au nanocuboids (NCs) as seeds was successfully synthesized by using the classic seed-mediated method. Electrochemical measurements were conducted to demonstrate their greatly enhanced catalytic performance in the ethanol oxidation reaction (EOR). It was found that the electrochemical performance for Au@Pt BNPs with the concave Au NCs as seeds, which were enclosed by {611} high-index facets, could be seven times higher than that of the Au@Pt bimetallic nanoparticles with regular spherical Au NPs as seeds. Furthermore, our findings show that the morphology and electrocatalytic activity of the Au@Pt BNPs can be tuned simply by changing the compositional ratios of the growth solution. The lower the amount of H2PtCl6 used in the growth solution, the thinner the Pt shell grew, and the more high-index facets of concave Au NCs seeds were exposed in Au@Pt BNPs, leading to higher electrochemical activity. These as-prepared concave Au@Pt BNPs will open up new strategies for improving catalytic efficiency and reducing the use of the expensive and scarce resource of platinum in the ethanol oxidation reaction, and are potentially applicable as electrochemical catalysts for direct ethanol fuel cells.

  20. Synthesis of Au@Pt bimetallic nanoparticles with concave Au nanocuboids as seeds and their enhanced electrocatalytic properties in the ethanol oxidation reaction.

    PubMed

    Tan, Lingyu; Li, Lidong; Peng, Yi; Guo, Lin

    2015-12-18

    Herein, a new type of uniform and well-structured Au@Pt bimetallic nanoparticles (BNPs) with highly active concave Au nanocuboids (NCs) as seeds was successfully synthesized by using the classic seed-mediated method. Electrochemical measurements were conducted to demonstrate their greatly enhanced catalytic performance in the ethanol oxidation reaction (EOR). It was found that the electrochemical performance for Au@Pt BNPs with the concave Au NCs as seeds, which were enclosed by {611} high-index facets, could be seven times higher than that of the Au@Pt bimetallic nanoparticles with regular spherical Au NPs as seeds. Furthermore, our findings show that the morphology and electrocatalytic activity of the Au@Pt BNPs can be tuned simply by changing the compositional ratios of the growth solution. The lower the amount of H2PtCl6 used in the growth solution, the thinner the Pt shell grew, and the more high-index facets of concave Au NCs seeds were exposed in Au@Pt BNPs, leading to higher electrochemical activity. These as-prepared concave Au@Pt BNPs will open up new strategies for improving catalytic efficiency and reducing the use of the expensive and scarce resource of platinum in the ethanol oxidation reaction, and are potentially applicable as electrochemical catalysts for direct ethanol fuel cells. PMID:26585310

  1. Multiplicities in Au-Au and Cu-Cu collisions at sNN=62.4 and 200 GeV

    NASA Astrophysics Data System (ADS)

    Prorok, Dariusz

    2013-09-01

    Likelihood ratio tests are performed for the hypothesis that charged particle multiplicities measured in Au-Au and Cu-Cu collisions at sNN=62.4 and 200 GeV are distributed according to the negative binomial form. Results suggest that the hypothesis should be rejected in all classes of collision systems and centralities of Pioneering High-Energy Nuclear Interaction Experiment Relativistic Heavy Ion Collider measurements. However, the application of the least-squares test statistic with systematic errors included shows that for the collision system Au-Au at sNN=62.4 GeV the hypothesis could not be rejected in general.

  2. Qualitative and quantitative analysis of felbinac and its major metabolites in human plasma and urine by liquid chromatography tandem mass spectrometry and its application after intravenous administration of felbinac trometamol injection.

    PubMed

    Zheng, Yunliang; Hu, Xingjiang; Liu, Jian; Wu, Guolan; Zhai, You; Wu, Lihua; Shentu, Jianzhong

    2015-04-01

    We present a method for the qualitative and quantitative analysis of felbinac and its major metabolites in human plasma and urine by HPLC-MS/MS and its application. Qualitative analysis through LC-Triple-TOF-MS/MS indicated that oxidization was the main phase-I metabolic pathway of felbinac in human, conjugation with sulfate and glucuronide groups produced at least 7 phase-II metabolites. Quantitative analysis through HPLC-MS/MS in MRM mode was developed and validated for the quantification of felbinac and its major metabolite (4'-hydroxyfelbinac) in human plasma and urine. Linear calibration curves were obtained for felbinac and 4'-hydroxyfelbinac in plasma and urine (r>0.996); intra- and inter-day precision values (RSD%) obtained were ranged from 1.13 to 6.49%, and the accuracy were between 95.9% and 108.6% for the two analytes. The pharmacokinetics and excretion analysis showed that the t1/2 of 4'-hydroxyfelbinac (8.25 ± 4.15 h) is a litter longer than that of felbinac (6.13 ± 2.01 h), but the mean AUC(0-t) value of felbinac was about 20 times higher than that of 4'-hydroxyfelbinac; excretion of felbinac and 4'-hydroxyfelbinac reached their peak values at about 3-6h after intravenous administration of felbinac trometamol in human. PMID:25706568

  3. Preparation of Nanoscrolls by Rolling up Graphene Oxide-Polydopamine-Au Sheets using Lyophilization Method.

    PubMed

    Yang, Yongfang; Zhang, Xiaolu; Wang, Hefang; Tang, Honghao; Xu, Lidong; Li, Hua; Zhang, Lei

    2016-06-21

    Graphene oxide-polydopamine-Au (GO-PDA-Au) nanoscrolls were prepared by rolling up GO-PDA-Au sheets through a simple lyophilization method. The structure of GO-PDA-Au nanoscrolls and GO-PDA-Au sheets were compared by powder X-ray diffraction, Raman spectra, transmission electron microscopy, and scanning electron microscopy. The results demonstrated that the heterogeneous GO-PDA-Au nanoscrolls were synthesized successfully. Polydopamine (PDA) attached at the surface of GO sheets served as binding reagents to anchor and disperse Au nanoparticles (NPs). The electrocatalytic activity of methanol with GO-PDA-Au nanoscrolls and GO-PDA-Au sheets as electrodes were conducted. Compared to GO-PDA-Au sheets, GO-PDA-Au nanoscrolls showed better electrocatalytic activity and electrochemical stability owing to their scrolled structure. This article provides a simple and effective method to prepare GO nanoscrolls containing metal NPs that broadens the applications of the graphene-based materials in optical, magnetic, and catalytic fields. PMID:27124218

  4. Efficient synthesis of core@shell Fe3O4@Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Alonso-Cristobal, Paulino; Laurenti, Marco; Lopez-Cabarcos, Enrique; Rubio-Retama, Jorge

    2015-07-01

    The synthesis of Fe3O4@Au nanoparticles has received much attention due to promising applications in the biomedical field. In this work, we produced Fe3O4@Au nanoparticles by using a two-step solvothermal route that employed Fe3O4 nanoparticles as seeds for the Au deposition. Although this protocol leads to highly monodisperse and reproducible Fe3O4@Au nanoparticles it was necessary to perform a systematic study to have a better understanding, improve the yield and allow us to obtain a tunable result. We demonstrated that the Au:Fe3O4 ratio is a key parameter that, contrary to what could be expected, does not influence the Au shell thickness. However, this parameter should be optimized because it strongly influences the yield. When the Au:Fe3O4 ratio was low there were plenty of uncoated Fe3O4 nanoparticles, whereas when the Au:Fe3O4 ratio was high there could be some pure Au nanoparticles together with the desired Fe3O4@Au nanoparticles. Furthermore we demonstrated that the Au shell thickness can be tuned by varying the reaction temperature. This paper describes the influence of both parameters and proposes a mechanism of the synthetic process by studying parametrically the morphological and structural evolution of the nanoparticles by TEM, DLS, SQUID and UV-vis spectroscopy.

  5. Qualitative and quantitative analysis of a group of volatile organic compounds in biological samples by HS-GC/FID: application in practical cases.

    PubMed

    Monteiro, C; Franco, J M; Proença, P; Castañera, A; Claro, A; Vieira, D N; Corte-Real, F

    2014-10-01

    A simple and sensitive procedure, using n-propanol as internal standard (IS), was developed and validated for the qualitative and quantitative analysis of a group of 11 volatile organic substances with different physicochemical properties (1-butanol, 2-propanol, acetaldehyde, ethyl acetate, acetone, acetonitrile, chloroform, diethyl ether, methanol, toluene and p-xylene) in whole blood, urine and vitreous humor. Samples were prepared by dilution with an aqueous solution of internal standard followed by Headspace Gas Chromatography with a Flame-ionization Detector (HS GC-FID) analysis. Chromatographic separation was performed using two capillary columns with different polarities (DB-ALC2: 30m×0.320mm×1.2μm and DB-ALC1: 30m×0.320mm×1.8μm), thus providing a change in the retention and elution order of volatiles. This dual column confirmation increases the specificity, since the risk of another substance co-eluting at the same time in both columns is very small. The method was linear from 5 to 1000mg/L for toluene and p-xylene, 50-1000mg/L for chloroform, and 50-2000mg/L for the remaining substances, with correlation coefficients of over 0.99 for all compounds. The limits of detection (LOD) ranged 1 to 10mg/L, while the limits of quantification (LOQ) ranged from 2 to 31mg/L. The intra-day precision (CV<6.4%), intermediate precision (CV<7.0%) and accuracy (relative error ±10%) of the method were in conformity with the criteria normally accepted in bioanalytical method validation. The method developed has been applied to forensic cases, with the advantages that it uses a small sample volume and does not require any extraction procedure as it makes use of a headspace injection technique. PMID:25124884

  6. State-Sensitive Monitoring of Active and Promoter Sites. Applications to Au/Titania and Pt-Sn/Silica Catalysts by XAFS Combined with X-Ray Fluorescence Spectrometry

    SciTech Connect

    Izumi, Yasuo; Masih, Dilshad; Candy, Jean-Pierre; Yoshitake, Hideaki; Terada, Yasuko; Tanida, Hajime; Uruga, Tomoya

    2007-02-02

    State-sensitive XAFS was enabled combined with high-energy-resolution ({delta}E = 0.3 eV-5.5 keV) X-ray fluorescence spectrometry and applied to Au sites of Au/TiO2 and Sn promoter sites of Pt-Sn/SiO2. Each state of interfacial Au sites located on Ti/O atoms and negatively/positively charged Aun clusters was discriminated. Feasibility of more direct information of on-site catalysis via frontier orbital-sensitive XAFS was demonstrated.

  7. Photoionization of Au+ ions and developments in the synthesis of the metallofullerene Au@C60

    NASA Astrophysics Data System (ADS)

    Bogolub, Kyren; Macaluso, David; Mueller, Allison; Johnson, Andrea; Müller, Alfred; Schippers, Stefan; Hellhund, Jonas; Borovik, Alexander; Anders, Andre; Aguilar, Alex; Kilcoyne, A. L. David

    2014-05-01

    Single photoionization of Au+ ions was investigated via the merged-beams technique at AMO Beamline 10.0.1.2 of the Advanced Light Source at Lawrence Berkeley National Laboratory. The relative single photoionization yield was measured as a function of photon energy in the 45 eV to 120 eV energy range. These measurements were made in preparation for future photoionization studies of the endohedral metallofullerene Au@C60, the production of which was also investigated. In proof-of-principle measurements a mass-resolved beam of Au@C60+was produced with a primary ion beam current in the single picoamp range without optimization of the ion source or synthesis parameters. Plans are presented for improved metallofullere production yield to be used in photoionization measurements of the endohedral fullerene ions in conjunction with the continuing study of pure Au. We would like to acknowledge the generous sharing of equipment vital to this work by Andre Anders, the Plasma Applications group leader at the Advanced Light Source, LBNL.

  8. Mn2Au: body-centered-tetragonal bimetallic antiferromagnets grown by molecular beam epitaxy.

    PubMed

    Wu, Han-Chun; Liao, Zhi-Min; Sofin, R G Sumesh; Feng, Gen; Ma, Xiu-Mei; Shick, Alexander B; Mryasov, Oleg N; Shvets, Igor V

    2012-12-11

    Mn(2)Au, a layered bimetal, is successfully grown using molecular beam epitaxy (MBE). The experiments and theoretical calculations presented suggest that Mn(2)Au film is antiferromagnetic with a very low critical temperature. The antiferromagnetic nature is demonstrated by measuring the exchange-bias effect of Mn(2)Au/Fe bilayers. This study establishes a primary basis for further research of this new antiferromagnet in spin-electronic device applications. PMID:22996352

  9. Reasoning about energy in qualitative simulation

    NASA Technical Reports Server (NTRS)

    Fouche, Pierre; Kuipers, Benjamin J.

    1992-01-01

    While possible behaviors of a mechanism that are consistent with an incomplete state of knowledge can be predicted through qualitative modeling and simulation, spurious behaviors corresponding to no solution of any ordinary differential equation consistent with the model may be generated. The present method for energy-related reasoning eliminates an important source of spurious behaviors, as demonstrated by its application to a nonlinear, proportional-integral controlled. It is shown that such qualitative properties of such a system as stability and zero-offset control are captured by the simulation.

  10. Qualitative Research: Comments and Controversies.

    ERIC Educational Resources Information Center

    Schutz, Robert W.

    1989-01-01

    This article comments upon the use of qualitative research in physical education, exercise, and sport science. Topics include unresolved methodological problems, data analysis, and the scope of qualitative research. (IAH)